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National Academy

“‘“

v

Of ..__ ‘Sciences 1-~ ~ ;:, , - National Ressarch Council .-1 I r g NUCLEAR SCIENCE SERIES .-. ,3 J :;.. k .-1 1: ,:1 : “i The Radiochemistry ;. .of the Rare Gases ,. s. -. ;r. ~ ., .--i . 1 .1 ..... , r r .,. i ..

Ii

i i’.-


COMMITTEE

ON NUCLEAR SCIENCE

L. F. CUR-, CkaJ~ National Bureau of ~anla

ROBLEY

D. EVANS, Vh

Mamaohuema

Ctinnas

Institute of Teohuology

J. A. IWUREN, Secrdury WeWl@mue Eleotrlc Corpratlon C. J. BO~ M RI* Nadooal

J.

W. IRVINE,JR.

Maeaachueetca

Laboratory

Nortlmeutem W. WAYNE Untverslv

SAMUEL EPSTEIN California Inetituw of Teohuology

Co~ratlon

of

NOW

York

D. M. VAN PA77ER Bartol Reaearoh Foudulon

LIAISON PAUL C. AEBER&XiO

J. HOWARD MO~EN National Solence Foudatlon

E. WRIGHT

WIIJJAM

OHlce of Naval Reoeamb

SUBCOMMITTEE WAYNE MEINKE, Chfnwux

ON RADIOCHEMISTRY HAHOLD NIBBY Mad Uhcmatory

of Mlchlgan

GREGORY R. CHOPFlorlda State Unlven9i~ GEORGE A. COWAN Loa Akuoa 6Ci~1fi0

MEMBERS CHARLES K. HEED U. S. Air Fome

AtOmio Energy Comnlionion

Unlverally

~~ of Mkhlgan

ROBERT L. PLATEMAN Iabmvltoire & Chhnie Phy81que

Amerioa

W.

UntveralW

J. J. NICKSON Memorial HoEJ@tal,

of Studada

HERBERT GO-ED? Nuolear Development

d Teohmlogy

E. D. IUEMA

ROBERT G. 00CHRAN Texan &@xhuml and Mechanical

U. FANO National Bureau

Illlanwa

GEORGE LEDDICO’ITE Oak RNational Labomtory JULIAN NIELSEN Hantbrd Laboratnrlen

Laboratory

ARTHUR W. FADLHALL ~nlvemi~ of Waahbgton

ELLIS P. STE~EHG &gonne National Laboratory

JEHOME HUDIS Brookhaven National Laboratory

PETER

EARL HYDE Unlverni@ of California

LEO YAFFE McGUl LInlvareilg

C. STEVENSON

University

(Berkeley)

of California

(L1vermore)

CONSULTANTS NATHAN BALL(XJ Cenma d’Etuda de l’Energle Mol-Da&

BalsIum

Nucleaire

JAMES DeVOE University of Michigau WILLIAM MARLow National Bureau of Smudards


d#6’J M733r. C,.1

The Radiochemistry of the Rare Gases

~

FLOYD F. MOMYER,

JR

Luwr6nc8 Radiaiia Labcwm WniveY8ity of Calijimtia Livermore, Calijbnch ,. . ... ., CMober

Iwo

PROPERTY

❑ ✎✿✎✎✎ ✎✎✎✎✎✎ ✎

subcommittee m Rndlochemistry of 8ciemces-Natiaid Research

Natimml Academy

PrMdin LIM. PAoo$0.75. b-ws,~~f=-u-m~*.D.c..

AW8MWhM

titidlbohiod

Calncil


FOREWORD

The Subcommittee on Radlochemlstry Is one of a number of subcommittees working under the Committee on Nuclear Science within the National Academy of Sciences - National Research council. Its members represent government, Wdustrial, ahd university laboratories in the areas of nuclear chemistry end analytical chemistry

The Subcommittee has concerned itself with those areas of nuclear science which involve the chemist, suchas the collection. and distribution of radiochemical procedures, the establishment of specifications for radiochemically pure reagents, availability of cyclotron time for service irradiations, the place of radiochemis.try in the undergraduate college program, etc.

This series of monographs has grown “out of the need for up-to-date comptlationa of radiochemical information and procedures. The Subcommittee has endeavored to present a series which will be of maximum use to the working scientist and F@ch monowhich contains the latest available information. graph collects in one volume”the pertinent information required for-radiochemical work with en individual element or a group of closely related ,elements,

An expert h the radiochemistry has written the monograph, following by the Subcommittee. The Atomic’~ergy the printing of the series.

of the partictiar a standard format Commission has

The Subcommittee is confident these publications useful not only to the radiochemist but also to the worker in other fields such as physics, biochemistry who wishes to use radlochemical techniques to solve problem.

W. Wayne Meinke, Subcommittee on

iii

element developed sponsored

will be research or medicine a specific

Chairman Radlochemlstry


INTRODUCTION This pared

Science

monographs The gas

cussion

on the early

sections

formation,

author

on the radiochemistry The Mr.

R.

A.

author

takes

for

for

appreciate

of the rare

gases

gases

was

pre -

of the Committee

as one of a series

and to some

.

of rare

rare

to general

devoted

The

last

gases

radioactive

of

three

from

rare

reviews

general chapters

targets,

gases,

of

disare

a dis-

and a collec-

gases.

receiving

or unpublished,

this

are

rare

counting

procedures

would

published

for

rare

the elementE.

monograph

of the removal

used

Council

to the radiochemimt

techniques

a discussion

of radiochemical

of all

of this

of interemt

of the

on Radiochemistry

Research

radiochemistry

of techniques

The

the radiochemistry

of the Subcommittee

of separation

cussion

with

of the National

propertied

respectively

tion

dealing

at the request

on Nuclear

rare

report

which

from should

readers.

any additional

be included

in such

ina report

gases.

opportunity

daRo za in the preparation

to acknowledge of this

iv

monograph.

the a,ble assistance

of


CONTENTS Foreword

.

Introduction

.

I. II.

General Table

.

.

.

.

References of Isotopes

III.

Review

of Features

Sample

Solution

V.

Counting Collection

Rare

. Pertinent

of He,

IV.

VI.

.

Ne,

1 – Removal

Kr Procedure

Removal

Procedure

6 – Separation

Procedure

7 – Removal

from

U03

from

.

8 – Determination

Wire

v

2

Etry

.

5

.

.

27

.

.

29 34

34

.

40

43

,

.

.

.

.

46

Xe

Product . 6 H20 Fission

Cathode

46

Xe Targets Gases

48 48

and its

of a Discharge .

of Active

by the Charged

.

.

Th Targets

.

1

.

Product

,

U02(N03)2

.

iv

.

and

.

.

of Long-lived

on the

.

and

Product

of Rn from

111 “’-

Gases

.

Purification 85 .

of Fission

or

Air

.

of Kr and Xe 235 Targets U

.

.

. the Rare

of Fission

Removal

Collection Tube

.

of Kr

of Fission

5 – Rapid

.

for

from

UMetal

.

Radiochemi

Separation

U Foil

Procedure

.

Gas

and Separation

UBee

4 – Recovery

. .

.

and Rn

and Xe

Products

from

.

Radiochemietry

.

Extraction,

from

Procedure

.

Subsequent

3 – Rapid

Xe,

in Rare

1 A – Removal

2 – The

Gas

.

with Carriers

of Kr

Industrial Procedure

Kr,

.

Procedures

Fission Procedure

.

Activities

Their Procedure

.

A,

of Interest

of Radiochemical

Procedure

.

to Rare

and Exchange Gas

.

Gas

.

.

49

.

51

Half-lives

Technique

(II)


The Radiochemistry

of the Rare Gases

FLOYD F. MOMYER, JR Lawrence Radiation Laboratory University

of CaUforrda

Livermore, I.

GENERAL

REFERENCES

H.

Treatise

Remy,

Anderson),

R.

T.

R.

and Sons

E.

Dodd

Chap. S.

Vacuum

2,

Elsevier

Brunauer,

I.

New

Keulemans,

York,

1959, A. .-

Charcoal

A.

Book C.

D.

Fission ~ooka 64-70,

and R.

K,

Products,

139,

of Gases

York

Compounds,

1949.

John

Chemistry

(1954).

and Vapors,

Press,

Ad~orption

Vql.

Princeton,

.1,

N, J.

Reinhold

ling,

Energy

York,

Laboratory

editors, Series,

I’Physical (1942),

Publishing

Co.

,

and Xenon report

on Activated

1092,

MLM-

McGraw-Hill 145-50,

Vacuum Div.

I,

Equipment Vol.

1,

and Tech-

McGraw-Hill

1949.

Sugarman,

National

141,

of Krypton

II Mound

Waker

Nuclear

and N,

2 and 3,

York,

1959.

, blC, , New

Coryell

New

Inor~anic

Chromatography,

llThe

Weller,

National Co.

S.

2nd edition.

Ohio,

Guthrie

niques,

Gas

and Sons,

of Volatile

, New

University

A Bibliography,

Miamisburg,

Wiley

by J.

(1956).

Experimental

Co.

Adsorption

RDIOCHEMISTRY

( 1948).

Robinson,

Princeton

M.

Lawrence

York

Publishing

The

Adsorption”, A.

L.

John

GAS

VO1. I (translated

, New York

Manipulation

, New

and P.

Co,

Technique,

Vacuum Inc.

TO RARE

Chemistry,

Publishing

Sanderson,

Wiley

PERTINENT

on Lnorganic

Elsevier

S. Dushman,

California

editors,

Nuclear Book 154,

Energy Co.

, Inc.

and 311-17.

1

Radiochemical Series, , New

Div. York,

Studies:

The

IV,

9,

Vol.

1951.

Papers


II.

TABLE

OF

ISOTOPES

KRYPTON,

Isotope

Half -life

He3

Stable

OF

XENON

Type

HELIUM, AND

NEON,

RADON

of Decay

(abundance

1.3

(abundance

1. 7X10-5%

X10-4

(abundance

-looyo)

ARGON

,*

Method

~Oatmos.

)

of Preparation

Natural

wells) Natural

He4

Stable

He6

-0.8

P-

Be9(n,

Ne18

1.6sec

P+

F 19(PF 2n)

Ne’9

-18

P+

F19(p,

sec

sec

a)

n)

Ne20

Stable

(abundance

90. 92%)

Natural

Ne21

Stable

(abundance

0.257

Natural

Ne22

Stable

(abundance

8. 827’)

Ne23

-40

Ne24 A35 A36 A37

A38 A39 A40 A41

A42

sec

min

-1.8

sec

Stable

(abundance

-265 Stable -110

(abundance

Kr76

9.7

Kr77

-1.2hr

Kr78

Stable

Kr79

34,5hr

Mg26(n,

a)

*’

Listed Isotopes”, Phys. 30, the ori~nal

n);

C137(d,

2n);

Ca40(n,

a)

a);

A38(n#y);

K39(nFp)

N“atural

P-

A40(d,

P); A40(n,

K41(n,

p)

P-

A41(n)~); Y89(p, ~+ -80910

parent

Y);

K

42

span)

Se74(a,

n)

Natural

o. 3547,) EC

(abundant

n)

n); K39(d,

957”,

~+57°

Se76(a,

n);

Br79(d,

2n);

(p, n);

Kr78(d,

p);

Kr78(n, Stable

C135(p,

C137(p,

Br79

Kr80

p) n);

Natural

EC-20~0, (abundance

p);

S34(a,

EC

hr

Na23(n,

Natural

99. 6007’0)

~3.5yr

p);

P+

P-

min

Ne22(d,

S32(a,

O. 063%)

yr

y);

Ne22(t,

EC

(abundance

Ne22(n,

P-

0.337%)

day

Stable

Natural P-

3.38

-35

~,)

y)

Natural

e 2. 27~0)

are those nuclides having an IIAII or IIBII classification and G. T. Seaborg: D. Strominger, J. M, Hollander No. 2, Part II, April 1958. Further information and literature may be found in said article,

2

in llTable

of

Revs. Mod. references to


TABLE

Isotope

OF

ISOTOPES

-10

Kr’1

2.1X105

Kr82 Kr83m

Stable

He,

Ne,

.sec yr (abundance

A,

Kr,

Xe,

and Rn,

of Preparation

IT

Brsl(p,

n);

daughter

EC

Kr80(n,y)

Se80(a,

n);

Kr82(d,

p);

Kr82(n,

y);

x-rays

on

of Decay

IT

. Kr83; Br83; Kr83

Stable

Kr84 Kr85m

Stable 4.36

11, 557.)

(abundance

56. 90!70)

U, daughter

~aughte

r Rb83

Natural;

~-78~0,

IT 22~0

Se82(a, Kr84

10.3

yr

Stable

Kr84(n,

P-

(abundance

P-

78 min

fission

U

Kr84(d, Rb85(n,

y);

fission

y);

Kr86(d,

p);

Rb87(n,

p);

fission

U

U,

Th

Kr89

3 min

P-

Fission

U,

Pu

Kr90

33

f3-

Fission

U,

Pu

Fission

U,

Pu

Fission

U,

Pu,

Fission

U,

Pu

Fission

U

Kr94

l,4sec

Kr97 xe121

1 sec

PF F PP-

40 min

P+

20 hr

EC

2 hr

EC,

9.8

Kr92

3. Osec

Kr93

2.0

xe122 xe123 xe124 xe125m

xe125 xe126 xe127

sec

sec

Stable

(abundance

IT

hr

Stable 75 sec

(abundance

1127

(?)

Th

PU

(p, 5n)

Natural 1127 (a,6n)Cs

O. 096~,)

55 aec

18.0

Fission U, 1127 (p, 7n) 1127 (p, 6n) f3+

U U

Kr86(n,

Fission

Kr9’

U,

fission

i=

aec

p);

fission 85 Br

2.8hr

Kr88

p);

a);

Natural;

17. 377.)

U

n);

daughter Kr85

fission

(n, y);

Sr88(n,

Kr86 87 ,Kr

81

fission

Natural;

(abundance

hr

Rb

Natural

11. 56~0)

114 min

(Cent’d]

Method

Type

‘Half - life

Kr81

OF

125;

daugh-

EC

ter Cs125 Te122 (a, n) Xe 124(n,

IT

Natural 1127 (a,4n)Cs

o. 0907,)

ter (Table

3

127;

y)

daugh-

Cslz7

Continues

on page

4)


TABLE

Isotope

~e127

OF

ISOTOPES

OF

Type

Half - life

36.41

He,

Ne,

A,

Kr,

and Rn.

Stable

xe129m xe129 xe130 xe131m X=131 ~e132 xe133m xe133

8.0

(abundance

(a, n);

IT

Stable

(abundance

26. 447.)

Natural

Stable

(abundance

4. 08~0)

Natural xe131

12.0

day

IT

(abundance

21.

Stable

(abundance

26. 89~~)

-2.2

18%)

day

5.270

(n, n’);

13-

fission xe134

Stable

xe135m

-15

(abundance

IT

fission

9.13

xe134

hr

P~e136

(n, a);

fission

(n, y);

Xe134(d,

Stable

xe137

3.9min

xe138 ~e139 Xe 140 xe141

Rn206 Rn207 Rn208 Rn209

Rn21 2 ~n215

(n, y);

PP-

Fission

U,

Th

-10

P-

Fission

U,

Th

P-

Fission

U

P-

Fission

U

Fission *U197

U

sec sec

-1

sec

f3-

-6

min

a65~0,

EC 35~0

-10

min

EC 96~0,

-22

min

EC-80~0, EC 83~0, a-96~0,

hr

EC

16 hr

a

23 min -10-6sec

(est.

)

a

74~0,

a470 a-20~o a 17~0 EC-4~o a26%

U

(N14, *U197(N14 Span

p);

Th;

Spall

Th;

Span

Th;

Span

Th;

U

fission

17 min

2.7 1

fission

41 sec

30 min

~n210 ~n21

P-

l. Osec

Xe 144

Natural; ~e136

8. 8770)

U

U

Fission

-2

~e143 8

(abundance

y);

Ba 138(n,

(n, 2n);

fission xe136

U

Xe 134(n,

(n, 2n);

Ba138 ~e135

U

U

U

Natural; xe136

10. 4470)

min

fission

fission

Natural; fission U xe132 (n, y); fission U xe132 (n, y); Xe 132(d, p); ~e134 (n,2n); Te130(a, n); ca133 (n, p); Be 136(n, a);

IT

day

(njy)

Natural;

Stable

1127( d,2n)

Xe Iz+n,y)

(p, n);

Natural xe128

1, 919L70)

day

of Preparation

~e124 1127

xe128

(Cent’d)

Method

of Decay

EC

day

Xe,

U

5n) , 4n)

span) Pb(C12, .Pb(C 1’, span) 12 Pb(C , span) .. span) Pb(C l’,

SpaU Th; Pb(C12, SP1l) 232 U-2 27 chain from Th (a, %)

a);


TABLE

16

OF

0.019

Ne,

(est.

A,

Kr,

Xe,

and Rn,

)

~228

from

Th

a

(a, 8n) ~229 chain

from

Th

a

(a, 7n) ~230 chain

from

Th

a

Member

(a, 9

Rn2

3.92

sec

of Preparation

chain

a

sec

(Cent’d)

Method

of Decay

sec

10-3

8

He,

Type

-10-4sec

Rnz17

Rn2

ISOTOPES

Half-life

Isotope

~nz

OF

232

232

232

6n) ~235

decay

chain Rnzzo

51.5sec

~nzz

1

25 min

Rnzzz

~- -80~’,

3.8229

day

Th232

Member

a

chain Thz32

a-20~o

(p, span)

Member

a

decay

U238

decay

chain

III.

REVIEW

OF

IN RARE

The krypton,

rare xenon,

of half-life One

can

gases

from

each with

from

the procedure Reviews in most

texts

chemically

chosen

literature

and

of the

other

to quantitatively

As

rare

greatly

helium gases

will

the further

often

be

simple

of the rare gases propertiesil 1 chemistry. In a practical sense,

They

will

remove

remain impurities

5

chemically other

unaltered than

rare

will

like-

generally

and in a regular

to radon,

concerned

monograph

separations

re-

and from

is ‘largely

gas

rare

However,

and xenon

products

‘Ichemical

on inorganic inert.

xenon.

rare

fission

sense.

four

be necessary.

in this

argon,

isotopes

remaining

of krypton

radiochemistry

discussion

varies

from

might

other

neon,

in the ordinary

of the

separation

gas

helium,

no radioactive

studies

separation

from

are

possess

one another

detailed

which

the group

the

is the

on rare

krypton

to include

and neon

elements

and most

property

through

by far

INTEREST

table,

radio chemical

and from

of heavy

around

on some

proceeds

are

The

problem,

center

depend

O of the periodic

in which

problem

OF

RADIOCHEMLSTRY

Helium

situations

fission

GAS

to permit

contaminants

other.

wise

enough

common

this

Group

and radon;

long conceive

the most sulting

gases,

FEATURES

manner

as

application

one of

if required. will

be found

the rare

gases

in any

reactions

gases

from

them.


rare

However, their

gas

atoms

neighborhood.

chemical

established.

the rare

Waal!sr’

for

solubilities

gas. ” A number

plicable

over” wide

ranges

comprehensive

studies

and xenon

gas

from

of organic

liquid

‘remember

moval ical for

rare

that

condensation of rare

gases

from

Thus

essentially

generally

liquids

the

gas

reasons

of the group

solids

Rare

gas

atoms of these

crystal

(one

rare

One

system may

solution,

corresponds

added

with

parti

tion

differences

to

or in reor phys -

usually

species

added

to be

recently

The

which

per

in some

loss

from physical

than

by

pressure.

crystal,

of rare

the gas

The

in the

actual

on the conditions

the theoretical been

described

to 25%

in the

of

limit.

prepared

for

use

reference

of the theoretical

as

re This

limit.

in the gas phase at about 25 atmospheres 85. per gram of clathrate (using fission The

of activity

material

and the 10Ss

day if the material

dissolve

operations

gases

preparation equal

prepared

ulting

markedly

krypton

have

considerable

molecules).

less

5~0 Kr 85).

on elements

of the rare

well

walls)

at high

on the amount quinol

depends

is about

no appreciable

chemical

crystal

of Kr

per .m”illion.

performed

stream

result

are

for

gas

the re;

considerably

in 3 curies

which

substances The

are

in the

to the concentration

powder

limit

ever y three

concentrations

and results krypton

other

gae

rare

within

an upper

for

and is usually

product

krypton

adsorption

carriers

are

of the

in “cages”

setting atom

of rare

in krypton

pressure

few

gas

of fission-product 85 5 activity. of Kr

sources

of the more

recovering

or solids

gas

carriers

an atmosphere

contained

cages

rare

crystallization

suits

under

are

number

Clathrates

on sol-

law is ap-

one does

(including

of

solutions.

quinol

concentration

known

number

(Henr yls

for

been

relatively

atomic

A series of substances known as clathrates has received 3,4 study, Clathrates of argon, krypton and xenon have been crystallizing

are

are

dependence

gas

amounts,

through

work

has

in a counter-current

liquids

phase

that

with

system

tracer

of other

+

and He2

in the literature.

absorption

or

+

volubility

a proposed

in

considered

of solvents

‘of the rare

appeared

phase

gas

or ions

here.

as HeH

increase~

of rare

in quantitative

‘the same

from

members

especially

with

the gas

properly

in a number

by their 2

gases,

contact

from

occlusion.

separated

streams

(kerosene).

in handling

heavier

gases

outlines

molecules,

is of no concern

pressure

) have

also

are

such

of studies

and partial

temperature,

atoms,.

of species

the four

solvent

other

inter actionfi

in nature

of rare

in a given

with

these

in discharges

Hydrates and

Volubility

vent,

der

existence

to exist, high.

Whether

or ‘Ivan

The

do interact

may

be ground

on standing

is protected

from

is

water

to a only

a

and

quinol.

involved

in separating

or compounds

other

one another

must

property

(usually

6

than

and purifying rare

gases.

be accomplished vapor

pressure

rare

gases

The

separa

on the basis or extent

of

of

-


It may

adsorption).

often

happen

that this

physical

rate

some

or all

of the impurities

other

rare

gas.

Thus

it is

necessary

the

rare

ical

gases

be possible

exist

as

Depending

Substances may

which

may

At said

being

to denote

critical

here

temperature

unsaturated

atmosphere

but which

that their rated

partial

vapors

fined

pressures

The

in the

word

context

often

be purified

in target

dissolution

must

of nitrogen, amounts

and occasionally

of elemental

of these. been

The

list

or could

small Methods

is by no means

be used,

pressures;

but it is hoped

must

as

that

and

3)

of air,

listed

and trace below

methods

it is representative

species

and otides

of hydrocarbons are

category, rare

volatile

halides

regards

be de-

The

from

satu-

vapor

is a large

small.

one

enough

of course

hydrogen

of removal

complete

than

appreciable

the above

amounts

less

but small

having

constituents

their

1 atmosphere;

are

is quite

as hydrogen,

from

halogens.

vapor

liquids

of

the term

above

than

which

temperature

1) gases,

appreciable

Although

the

such

to those

greater

encountered

from

limited at the

-

amounts

be necessary.

phase

in the foregoing

usually

in a radiochem

will

pressures

their

or

of the experiment.

gases

are

sepa -

to purify

and their

of substances

vapor

than

solids

‘Iappreciablelr

of contaminants

involved

less

steps

include:

in amounts

with

the number

will

pressures

whose

or

species

gases

also

a particular

convenient

step

amounts

vapor

are

in equilibrium

pressures.

this

appreciable

present

most

in the gas

will

from

whatever

rare

temperature

are

nor

operations

substances

gases

as the first

contaminate

or having

vapors,

separation

rare

contaminating

concentrations

the experiment.

2)

a group

upon the

that no chemical

in appreciable

used

neither

chemically

procedure.

it may

often

than

for

which enough

each

have to be

useful. 1)

Nitrogen:

with

titanium

(ea.

850°C)

Quartz the

Mole

sponge, has

14-20

been

or ceramic

softening

point

amounts mesh

reported.

6

furnaces

are

of Pyrex

glaes

so the temperature

must

prevent

of the furnace.

destruction

to remove passive this phase

nitrogen through

problem with

nitrogen 2) gen also 3)

may at

be quantitatively 1000 -11 OO”C.

Oxygen necessary es .

(400 -5.00 ”C).

reaction

and flow Calcium

Calcium

of surface

Use

films.

has

temperatures

been

however,

For

small

are

above

exothermic

of the gas

often

does,

temperatures

quantitatively.

is quite

rate

by reacting

of lower

removed

as these

The

be monitored

formation

is also

removed

and

controlled

used tend

amounts

to

satisfactorily

to become of impurities

is

sometimes circumvented by conducting the reaction in the gas 7 Ca vapor. Clean uranium turnings at 800 “C will also react with

(and decompose Oxygen: reacts

Will rapidly

Hydrogen,

hydrocarbons). be removed with

carbon

with

copper

nitrogen

turnings

monoxide,

light

7

in the above

above pa,raffin

350”C

reactions

to give

hydrocarbons:

.

Oxy-

CUO. Passage


of the gas

stream

rapidly.

over

CUO

Hydrocarbons

temperature moval

will

of 900”C

of oxygen

temperatures

oxidize

that

in like

to achieve

be necessary

used

will

be oxidized

is necessary

may

are

at 500”C

HZ to H20 manner

rapid

(and is easily

9

and CO

to H20

and C02

reaction.

pregsure

to condensation

of water

but a

Subsequent

accomplished),

the dissociation

to C02

re-

if high

of oxygen

over

enough

CUO becomes

appreciable.

often

4)

Water:

not

specific

of a number

In addition enough),

water

of desiccants

.

may

P205,

be removed

Mg(C104)2;

in cold

traps

by passage and CaC12

(a method

through

are

any one

representative,

with

equilibrium partial pressures of water over them at room temperature -5 and O. 2 mm Hg respectively. Ofzxlo , 5 x 10-4, P205 and CaC12 rep-

resent

the

chlorate poses

extremes

has

of efficiency

achieved

and is easily

Where

large

CaC12

to remove

maining 5)

by distilling are

involved,

of the water

dioxide:

Ascarite,

May

and then

impregnated

with

of NaOH

and CaO

solution

of alkali

metal

convenient

.

enough

Magnesium

for

per -

practically

all

pur-

the water

off in vacuo

at 220-C,

gases

often

first

with

are

dried

Mg(C104)2

Hydrogen

7)

Oxides

by passing

commercial

with

to remove

may

also

re -

systems

than

May

be removed

halides:

Sweeping

effective. solid

through

which

Sofnolite,

be used.

is also

the gas

preparation

hydrotide.

sodium

hydroxide

in vacuum

6)

be removed

a granular

mixture

leas

as it is efficient

of water

most

desiccants

of moisture.

Carbon

asbestos

use

regenerated

amounts

traces

containing

wide

in common

is

a trap

essentially

or soda-lime, the gas

Solutions

materials,

a

through

are

a

sometimes

“however.

in the same

manner

as carbon

diotide.

in evolution

2 small

in relatively reduction

with

solution

tion

are

oxides available

may

often

to be removed. zero

gas

through

change

oxidation

the gas

into

Free

a solution

to non-volatile of the halogens

most

will

be accomplished

are

all

relatively

amounts

in targets

solution

process

leaves

of sodium species their

will

hydroxide (halide

will

rapidly

and hypohalite

corresponding

8

them

halides

a

N02

may

hydroxportion

methods

of

of solu-

of nitric

acid,

and active which

partly

be contaminated.

and

a good

the use

from

occurs

with

of sodium

volatile,

in trace

stream

wash

result

by catalytic

NO

If alternate to avoid

will

usually

the gas

a solution in fact

flask.

convenient

acid N20

by scrubbing

through

reflux

the dissolver

the gas

with

may

.

as permanganate.

#tream

under

in nitric

proportions

to NO

such

halogens

If the state,

removal

agent

solution

back

of targets

in varying

2

Its

oxidizing

be present

are

NO

or by oxidation

it is often

the

halogens

Dissolution

and

amounts.

the

8)” Halogens: gens

NO

by sweeping

Performing

the higher

O,

hydrogen

of strong

be removed ide.

of nitrogen:

of N

rare

halogases

or entirely Sweeping

in the

convert all the free 10 The rapid ex). in solution

is another


useful

means

titatively used

of decontamination

removed

as a trap

by contact

packing

for

from with

this

tracer

silver

halogens

(silvered

purpose).

Iodine

11, 12

.

Raschig

Iodine

rings

is reduced

is

have

quan been

to iodide

in NaHS03

solution. Where pleted

dissolution useful, with

device

which

These

for

rates

consist

used

may

Alternate

be useful

rates

may

in particular

of a c’hamber

designed

and cooling

is the

to permit

pressure

hour.

and electromagnetically operated has 14 Pressure differentials developed minute,

per

the chamber 15

pressure

Another

achieves

by means

Other been only

rates

circulat-

designed. unidirectional within

the

of a few

not noted

similarly

of a mylar

target

generally 13 pump,

in the chamber has been 13 An iron piston enclosed

were.

small.

from most

changes

produced

probably

not be com-

Toepler

have

in glass

but are

off gases

be obtained.

of the gas per

may

and still

instances

periodic

of O. 5 liters

the

classic,

of gases

minute

of producing

heating

flow

The

(or transfer) per

that purification

to circulate

train.

a liter

essentially

to achieve

S1OW enough

be necessary

circulation

and a means

chamber.

are

a purification

of about

which

of gas

rates it may

through

ing pumps

flow

reaction

in one pass,

high

diaphragm

in the

flow

rates

driven

liters

reference by pulsing

by high

pressure

gas.

Ultimately properties

the radiochemist

of the rare 16

of interest.

gases.

must Table

concern

1 summarizes

Table

He abundance

Atmospheric (Volume

x 10

%)

1.82 -4

with

some

the physical

data

which

may

A~

Kr

0.934

1.14

-3

Xlo

Xe

w 6 x 10-18

8.7 -4

Xlo

Xlo

-6

Boiling

Point

( ‘C)

-269

-246

-186

-153

-107

-65

Melting

Point

( “C)

-272

-249

-189

-157

-112

-71

3.82

3.94

4.36

(25 Atomic

diameter

in

crystal

(angstroms)

Distillation for

separation

successfully

and radon

and adsorption of the

rare

of helium

which

is

techniques

gases.

The

commercially which

obtained

) 3.20

3.57

produced

the exceptions

atm.

be

1

Ne

5.25

himself

are

pure

rare

those gases

by the fractional

is extracted

as a member

9

from

which have

Texas

natural

come

of course

distillation

certain

of the 4n+2

first

----

to mind been

of air, natural

radioactive

with gases decay


series.

Fractional

distillation

istry

and the fractionation 17-20 places . Glueckauf air

to use

there

will

such

low

be used rough

air

texts

on physical

is discussed

combining

in practically

red

every Thus

till

prove

to the generally

necessary

for

pressure

chem -

in numerou8

fractional

distillation

of

for

which

Efficiencies

pressure

of its

ample,

solid

the vapor

99V0 of the Kr cold

veniently

available

amounts enough

The

of necessity

a system, absorbents

such

resort

as

gases

such

krypton

inter diffusion sure

orders

Kr,

of below

Xe,

curves

is often

losses,

for

is 2-3

Rn at low

seriously

lower

Thus

may

one wishes

in manipulations “he may wish to perform. -6 10-5 to 10 mm Hg are easily constructed

rates

IQ

to 2-3

and will

krypton

small

vapor

mm

of small

slowness system pressures

with base suffice

If one Hg from

refrigerated

of transfer

a vacuum

Systems

initial

be made

Presence

the lowest

at

and convenience.

due to the relative

than

con-

and the [argest

refrigerants,

the

an ex-

in an attached

increasing

they

pumps.

As

so roughly

the coldest

systems

comparable

temperature

or Toepler

lower

with

of speed

at pressures

trap.

by condensation

smallest

usually

conby the

to the vapor

be collected

manipulated

sake

species

determined

“mm Hg,

is generally

decrease

--

the

are

in the system

may

nitrogen

condensation,

processes.

vapor

temperature

in the cold

at -195°C

by using the

to lower

of magnitude

data

In order

of a gaseous

species

Hg pressure

Kr

krypton

may

for

tabulates

pres sure

system

condensation

practicable

charcoal,

is refer-

22

Physics ) also

as

commonly’

reader

A and 02,

vapor

to the

of the

liquid

acceptable

of noncondensible as the above

As

resultant

collect

he must

N2,

as the transfer

Kr

at 20 cm

carrier

the y are

and

et seq.

at a given

are

have

attached

after

be minimized

of krypton that

in pairs

of solid

refrigerant,

and may

pressure

pressure

at - 195°C.

species The

at low temperatures.

gases

such

trap

or liquid

in a system

trap

781

pressures

similar.

partial

pressure

temperature.

pressure

very

volatile

will

or effecting

) of vapor

Chemistry

(page

vapor

listed

to a cold

of the initial

of

of substances

of processes

in a system

small

are

and other

Handbook

the common

so

processes

gases

t~mperatures

to the radio chemist.

Dushman23

Gases

condensation

and

low

gases

(decreasing

and H20.

temperatures

rare

in the laboratory

in transferring

( for

handy

a number

temperature)

and C02,,

relation

for

a plot.

volatility

the critical

experiment

very

columns

here.

distillation

a plot

available

such

data

decreasing

tained

simple

of temperature

encountered

fractionation

of the method

hand,

separations.

a function

eous

a procedure

temperature

be no discussion

On the other

pres

in most

from

techniques in the determination of krypton and xenon con21 It is very ~likely that the radiochemist will have of the atmosphere.

need

must

used

gases

and ads orption

tents

this

is discussed

of rare

for

amounts

proces

sea

of gas with

a base

involved

pressures

of

the,” rnamipula-


tions

involved

than

tracer

in most

amounts

Removal when

of only

than its

tially

their

stream

lost

(passing

pres

sure

cold

through

prevent

are

isfactory.

materials

Such

the induction condensed must

be allowed

movable

gas

Ln like ities

may

The

in most nitrogen

will

It might

are

to its

commonly to obtain

refrigerants

ice

(-78.

triple

obtained a partially provide

by cooling

be’tter

heat

be touched

in handling

dry

liquid

are with

at the melting

transfer

xl

from

the

necessary each

to effect

trap

to time

com(e. g. ,

Liquid

commonly

than

Hg).

mm

-

and distilling

materials

gases

96.4

and ice

volatil

temperature).

nitrogen

a suitable

Ilslushll

trap,

on liquid

ice,

re-

useful.

times,

are

lower rare

packings

easily

on briefly.

(O”C)

of

in traps

of trap

of the volatile

and ice

by

removal

It is often

at dry-ice

sat-

be warmed

temperature

cold

bails

very

differing

several

beads

steel

of some

is often

trap.

behind

should

(-2 10, 9*C,

frozen

cold

temperatures

nitrogen,

cooling

of widely

condensate

that pumping

point

of liquid

transfer

traces

5-C)”,

not be required be noted

As

and to

wool,

proved

may

To

and

area

to be reached

to the other

-ice

Fortunately

usually

to those

C02

refrigerants

dry

laboratories.

evaporation

ice

from

8“C),

another

evolved

steel

to a suitable

remaining

or dissolved

of trap

(- 195.

and neon.

mediate

of C02

subject

nitrogen

into

also

introduction

materials,

limited

and efficient

flow.

heat

by warming

material

rapid

vapor gases.

Stainless

have

that the

gas

are

Glass

purpose.

plugs

temporary

condensate

of occluded

the distillation

initiating

condensed

components

the volatile

this

simply.

of its

contact

materials.

equilibrium

to improve

be separated

the

wool

thermal

slow,

several

volatile

removal

before

be quite

fashion

for

the ,advantage

for

as helium

and refreeze

removing plete

such

often

the more melt

may

used glass

rates

of the

of species

in the influent

flow

higher

quite

the fraction

a large

-

conditions

passage

i~ the ratio

to provide

in it to achieve

Time

phase,

essen

are

equilibrium

sure

conditions,

of condensed

has

currente

pres

is

separation

stream)

partial

material

suitable

a packing

materials.

vacuum

the gas

to its

commonly with

of eddy

always

under

conditions,

sufficiently

constituents

Ass uming

equilibrium with

some

of other

the desired

blow-through

in. ) combined

rather

is feasible

is

condensation

in the condensed

to equilibrium

with

macro

stream

pressure

that

effects

the trap

mechanical

or rings

trap

temperature

packed

that

a gas

vapor

stream

the trap:

speciee

under

the approach

traps

(3/16

other

from

its

pressures

over

the cold

occurs

at trap

improve

the vapor

of the

through

(assuming

species

at which

in the gas

pressures

Lf condensation

volatile

pressure

while

partial

and insolubility gqs

radiochemistry

can be found

partial

complete,

than

gas

involved).

the least

a temperature

less

rare are

that

of liquid

other will

available

than helium cool

it by

Temperatures often liquid

point. than

inter

necessary nitrogen Slush

solid

or

and or

dry

liquid

refrigerants,

-


thus

dry

ice

-78.

5”C.

is usually

mixed

useful

in working

and isopentane,

with

most

quantities

of gas

will

are

easily

replenished

other

temperatures up only

have

activated

surface

variables

on

at constant

adsorbate

are

adsorption

sure

change

with

A number of which

isotherm

for

Brunauer, sorption

which

P/v form

=

reduce

l/bv

s

+ P/vs

a monolayer

,

per

also

(shape

and the nature useful

P/v

P

is linear.

v~

been

at

they

need

in the

“C,

litera

showing

adsorbed

cc STP

Hg)

of gas

and partial

the

heats

among

dependence

and

T

of

v

at constant

Ln experimental

v;

studies

at a series

may

per

relationships

P

determined

relates

of

of tempera-

be obtained

if desired.

of adsorption

and the pres

of the isostere).

been

used

to express

Langmuir

from later

derived

v

is the

for

in the case

cc STP

of the adsorbate

derived

considerations.

equations

= vsbP/(1

of adsorbent,

adsorption

first

theoretical

Is equation

the extension

mm

it and

extents.

as

functional

P .

because

unit mass

the amount

expressed

-

of adsorbent

used

per

differing

relating

usually

have

where

often

of the ad~orbent

Three

in nature.

gram

particularly

for

such

traps

where

capacity)

relationships

be written

temperature

versus

most

to Langmuir may

since

number

material

at constant

adsorption 27 and Teller

isotherm

large

to be found

to widely

Isosteres

T

equation

empirical

most

1) Isotherms

monolayer

Emmett,

hfierbolic

-130

which

or ice

ure, i. e. , O“C and 76o

the other

temperature

are

has

of temperature

and

of equations

gases

v and usually

2)

are

-Clapeyron

ice,

Of the large

the adsorbent.

v

data

of rare

and adsorbent

of interest:

these

through

operations

adsorptive

called

the isotherms

Clausius

most

gas

and Press

relating

From

The

n-pentane,

“Slush- cooled’l

for

on charcoal

temperature;

3 ) Isobars

tures.

adsorb

over

dry

be reserved

charcoal

is a function

these

nitrogen,

(largest

of adsorbent,

of the gas

traps

on the line.

techniques.

area

gases

adsorbent,

liquid

of separations

Temperature

pres sure

-95 *C,

Techniques

available,

a given

(Standard

P

at

of heat.

adsorption

unit mass

and

amounts

the rare

to refrigerate

usually

the majority

the largest

For

acetone,

gases:

in place

employed

materials

gram

with

and Adsorption

By far

per

flow

may

small

Adsorption

rare

convenient

traps

because

refrigerant

- 160”c.

It is usually

has

a slush

of cold bathe may be found in most texts where vacuum 24, 25 discussed. The author has found the following baths par -

are

titularly

ture

to provide

Discussion

techniques

take

with acetone

and

tbP)

,

12

multilayer

= vfi(vs

of adsorbate b is a constant

“and adsorbent.

or perhaps

the hyperbolic 26 ad-

of a monolayer. P

more

The

–v)

required

, or to

dependent The

of data by interpolation

At low pressures,

isotherms,

since

last

on

form

the plot

definitively

is of low

-


it is found

v,

a linear than

plot

l/b,

of

or

law with

that adsorption P versus

v much

k equal

and

equation 2 for

handy

tabulated and as

reference.

in Chapter expected

creasing

order

LeChatelier

increasing

as

other

volatility

the boiling

(extent

points

Table

2.

tends

Adsorption

constants v

= KP

surfaces, is

and

considered

its

3)

indicated

by the fact

of condensation

over

wide

therm)

ranges

for

constants

models

used

of van der

that heats

values

2)

condensation

releases

decreases

with

Ad~orption

gases

tends

to increase

are

heat in-

increas

-

to increase in the

same

in terms formation

forces

of the

constants often For

to the literature on the subject 23 or to S. Brunausls 8 in Dushman

same

generally

(as

related

of adsorption is referred

13

on physical

may

in is

to the conform

However,

discussion

book

involved

in adsorption

isovalues

to the physical

the

reader

of a gas

the hyperbolic

in the equation.

not easily

type

of

on plane

comparable

isotherms

equations

1) formation

Adsorption

resulting

Experimental

derived

are

are

of:

of multilayers

pores.

Waal’s

gas ,

of the

in the derivations.

0.950 1.0 1.0 0.711 0.885 1,0 0.574 0.692 0.77

in small

of adsorption

a given

obtained

krypton

1/n

of the interactions

to theoretically

thus

in Table

on charcoal

for argon, 1/n

adsorption

surface,

magnitude

for

Euitable

of the

a key

capillary

The

heat

discuss

on the

the result

condensation.

given

process

0.500 0.0764 0.0581 2.927 0.497 0.340 15.99 2.458 1.583

,

treatments

of adsorbate

where

of argon,

K

0 -80 -18 0 -80 -18 0

Theoretical a monolayer

in cases

of the gases).

-80 -18

Xenon

in

of gases

constant.

of different

less

to Henryrs

in the Fr eundlich are

adsorption

T “C

Krypton

constants

a number

of adsorption

and xenon:

Argon

plot

These

remaining

Adsorption

much

the adsorption

adsorption

IS principle

factors

pressure.

for The

.on

(semi-empirical

on a log -log

the

P

reduces

equation

temperatures. data 23

that for

isotherm

studied

and calculated

at several

and interpolation

be noted

parabolic

interpolation 28 and Weil

Peters

8 of Dushman.

from

decreasing

linear

Adsorption

temperature,

es with with

data

(v = kP),

It will

Freundlich’a

on charcoal

their

law

v~ , the hyperbolic

than

to bv

xenon

from

Henryfs

v is possible.

less

s“ nature) is often useful for 1/n . it is obeyed: v = KP krytpon

obeys

in” general

to Chapters 29 adsorption.

and 7 and


Some These

comments

are

mostly

ous

materials

ods

of preparation,

from

heat

in the absence

than

carbon

with

steam

the order

on the nature

from

two

of air

as volatile

materials

1000

square

to the nonporous

surface

area

gram

particle

size.

resides

that

therm, coal

give has

so over

is dependent

Charcoals

low adsorptive

capacity

out more

pores

(perhaps

both

reaction

is endothermic,

then

depend

to diameters processes

that

the history

of its

through

a mafimum

will

surface

includes

many

accommodate

molecule.

as jhe

not be increasing

referred

to as an allotrope

percents

of carbon

other

elemente

It appears surfacee

likely

but are

to some too

the adsorptive in the

same

of carbon, less

thh

principally chlorine,

surfaces e urfacee

small

capacity

ratio.

modified

lJ+

adsorption

the

One

markedly

ex-

on

can in fact

capacity

going

the distribution to molecular extent. for for

analyses as

ash

some

a slightly

has

may

occurs

by the presence

of pores

dimensions,

Thus

various

and oxygen,

and inorganic

on which

very

and eometimes

hydrogen

as

in the laboratory

Charcoal

but elemental 100%

are

that the

comparable

molecules

activation

Since

) still

essentially

activation

but also

the adsorptive

be expected

porous

is possible.

Excessive

sulfur,

but hydrocarbon

for

than

diameters

of pyrolysis.

or to enlarge

adsorbate

he receives

proceeds.

of a char-

consists

new pores

used

iso-

generally

(though

control

in preparation

molecule

always

present

of nitrogen,

temperature

it creates,

on charcoal.

of coal

and activation.

may

activation

therefore

amounts

is widely

of the material

with

a given

During

open

It

structure

of activation

to either

accommodate

activation

effect

pore

pyrolysis

will

ueed

area

sieve!!

after

of

apparently

the hyperbolic

grades

.Steam

and better

pyrolysis

more

as to size

which

occur).

on materials

remove

a Bimolecular

in order

the properties

not only

material

size,

dimensions.

and the conditions

and certain

specific

the surface

independent

adsorption

potential

and the process

material

existing

pects

The

large

Thus

in charcoal

to obey

material

nutshells

porosity.

monolayer

The

the starting

area

(of as

particle

to� molecular

be expected

ranges.

whose

is almost

surface

activated

porosity,

size.

of the average

charcoal

principally might

hardwoods,

the highest

function

comparable

wide

on both

from

of burning

expect

black

and

other

of charcoal

high

-

meth-

shells

is then

area

particle

while.

ntimer

and many

coconut

material

ae lamp

are

of the elements

due to its

small

of the

with

surface

is

such

most

on charcoal

and does

gram)

of activated

diameters

one might

adsorption

per

is a marked

surface

with

resulting

of extremely

Furthermore,

in pores

follows Thus

black

the specific

part

specific

be worth

There

be prepared

start

absorbents

is the result

of lamp

whereas

meters

may

one might

large

may

charcoal 30,31

the greater The

.

The

articles.

charcoal

to remove

at 7OO-1OOO�C. of

of activated review

which activated 32 For example,

opposed

per

recent

pores

larger

species

may

in the past indicate low as

been

atom

757..

The

but appreciable also are

be preeent. not carbon

of oxygen

and


traces

of other

likely

elements.

charcoal

physical

properties

that this

does

tive

properties

that

even

tion,

adsorption

varied

a range

coal

for

both

use

sites

are

very

whose

accumulation This

through

further

gassing

in vacuo

judged

of five.

“’”

years’

may

process

One

may

differences

should

prove

useful

arations

to point

of species

chemists

who

analogies

are

even

mind

--

adsorption

stated

earlier

on particle

size,

(per

through

cracks

The if the ad-

quoted

in the

charcoals

early

at room

to produce

experience

may

in systems a quantity

it is necessary with

be

built

of char -

ways

with

to achieve

expected

ion

is out-

less

as

manifold. of gases

basically

such

the out-

Hg or

adsorbent).

resins,

using

resins

through

It may

similar The

to sep-

many will

that

with

radio-

note

close

considerations

rates

of charcoals

diameter

adsorbate

in the particle

does

of adsorption

will

increases

to the gas

15

kinetic

is not an instantaneous

capacity

particle

cites

are

the material

used.

of gas

which

mm

system

other

exchange

be designed

presented

along

10

of the

Laboratory

separations

(or any

techniques

a stream

is

as water)

satisfactory -4

char-

of residual

(such

to change

proved

Radiation

separations

amounts

properties

in the vacuum

separations

must

small

to outgas

materials

as

has

the pressure

using

adsorbent),

adsorption

which

the adsorptive

and pores

adsorpso critical

of separa-

expected

the adsorptive

gauge

such

in the average

gram

to reach

from

but it is

A reduction

surface

until

in solution

that

he sees

that

adsorbed

on charcoal

procedures

in loss

on seven

purchase

At Lawrence

out that

not

in detail,

of separations

uses

affect

in various

in the various

Separation

Ln order

of samples

vacuum

familiar

those

not be so extreme

continued

operate

result

and preparations

A routine

in the adsorption

The

usually

to add

needs.

adversely

by a thermocouple

UH hasten

not be surprised

of xenon

successive

at 350-400°C.

routinely

from

and to remove

activation.

will

to originally

contamination runs

are

the prQcedure

the course

wise

Let

and

of charcoal adsorbed at a given pressure 33 These charcoals were of course chosen

.

accuracy

many

pretious

charcoal.

gram

chemical

as an adsorbent.

should

differ

whose

limits.

systems

affect

in materials

fair

to prevent

from

is

per

and between

gases

gassing

charcoal

it is probably

Before

wide

of two or more

characteristics

with

dates,

usefulness

of the adsorption

as a factor

sufficient

coal,

of his study

of adsorption

at later

its

certainly

of differences

to predict

rather

factors

the amount

as much

within

out that the experimenter

In one

on the ba,sis

used

like

of substances

in separation

variations

properties

temperature,

order

that all

a class

impair

charcoals

such

is to point

sorptive

vary

not really

variations

literature.

is thus

may

of

though

intent

ent.

implies

not identical. Activated

was

This

phase

molecules interior.

the

process.

It

not depend be so dependexterior

and shortens must

in’

paths

diffuse

Approach

in

to equi -


librium

conditions

creased

contact

is necessary flow,

time

In flow

systems

occurring

thus

est

and

long-range

factors

procedure where

that

these

necessary Most

rare

of interest

problems

arising

variations,

steps will

than

slow

from

processes

in actual

In their

early

and xenon

resorption

could

on charcoal

at

and then

fer

them

may

to a gas

speed

buret IIpure!i

and separation

of adsorbent adsorbent calculate

and of each bed

distribution

Peters

of all

may

minimize

temperature

all

and Weil

by total

adsorption They

10CC STP

the trap

of each

and more

adsorption

steps

deaorption in detail

pump

--

but

on”the

each

lift

but laborious phases adsorbent.

16

after

by fractional

on 38 grams and desorbed p~p

to trans

at which

each

a compromise

at -93 ‘c,

knowledge

that argon,

the mixture

used

by a ToepleT

somewhat

initially,

before

was

temperature

backed

of argon

From

showed

followed

Temperatures are

removal

adsorbate

28

adsorbed

gas

to a suitable

measurement.

and gaseous

of the gases

one

separation

charcoal.

in a straightforward

in the adsorbed

adsorption

in subsequent

separated

be typical.

is equilibrated

not be

temperatures

activated

of the others

factor

at O“C would

total

By treating

gases,

diffusion

for

be under-

of sample.

(roughly

raised

a mercury

be desorbed

and xenon

gas

- 190” C

using

be

the

Procedures

or may

manner

of the

kinetics which

it should

of sample,

10S ses , since

the history

on rare

from

of charcoal) the gases

loss

this

and the

desirable.

with

lower

be necessary.

affect

work

in vacuum

by using

to reduce

may

under

introduction

kinetics

really

affecting

but may

-

inter -

empirical.

factors

be quoted

trans

of these

is

as the Detailed

commence k

of heat of great

the kinetics

changes

trap.

non-uniform

one tends

not result

will

in an adsorbent

should

manner

krypton

separations

make

the rate certainly

conditions

may

at ele processes

as possible

the separation,

considerations

and adsorption

adsorbent in this

for

such

sizes

the bed

insofar

succeeds,

in places

to gas

not be maintained

to design

the kinetics

particle

sufficient

gas

in detail

A compromise

the adsorption

it is

the extreme

Thus

may

affecting

approach

and in-

resistance

enters

from

Although

to improve

to determine

other

the gases

release

Lf the experiment

are

should

of heat

beds

if the gas

size

rate),

in high

adsorbent

and faster

and charcoal

flow

result

to understand

satisfactory.

rates

will

and conditions

practical

particle

(decreased

size

respect.

usefulness

not varied is

flow

rates

are chosen

smaller

the refrigerant

in this

is tried.

usually

stood

important

with

temperature

with

the more

experiment are

low

Flow

is hi,gh.

are

Design

particle

or if the rate

fer

processes,

improve

the adsorbent

small

equilibrium

temperature

thus

with

as too

in thermal vated

should

gas

between

krypton

at -800c

of the isotherms,

amomts

and the volume

with

which

the

of the Toepler

pump

one

could

fashion each Even

the composition stroke,

cursory

-

assuming examination

of the uniform of the


isotherms duce

suggests

gases

the limit

are

obtainable

It might

be noted

a system series

system

rare

uranium

later

mass

traps

waa

they

point

charcoal liquid traps

out,

densation

silica

today

rather

column,

a charcoal

bed

sample a flow 2)

of Peters

on a

helium

and

and xenon

isotopes

gases

a series

and

of many

by what

may

involve

Rare

gas

solid

Methods one of three

of the gases of slightly analysis

to be

adsorbed

of operating

separated

is adsorbed (eluent) of gas

17

the

determination gases

by elu -

in the He and Ne 36 will serve as

will

be made

separations which

a stream

at one

or

of gas

as

moving

gas -solid

columns

will

in which

genera

end of the column

up through

containing

and

a sta:

of liquid

a stream

development

set

here

involve

be classified

chromatographic

gas

in “which a stream

used book

end of an

through

the rare

involve

would

1 ) Elution

categories:

carrier

gas

remarks

on charcoal and thus

above

and as an up-to-date

Chromatographic through

con-

chromatographic on one

later

chromatography

adsorbent

mentioned

in his

recent

pressure

to avoid

eluent

separated

to use

charcoal

at reduced

termed

of some

As of

advisable

nitrogen

Glueckauf

Glueckauf21

gel.

potentialities

of a sample

a few

silica

to refrigerate

be generally

Only

ont~

it seems

than by the method

of gas

of solid

air

in liquid

Keulemans’

separations

column

it was

and of

passage

references.

or

in which

hazard

of the atmosphere

cited.

an experiment

and to operate

In fact,

subject

to

liquid

adsorption

rather

mentioning

cooled

and Weil

mentioned.

to the

a packed

Frontal

separating

of

. 1s worth

or oxygen,

of breakage,

column

of liquid

into

air

itself.

references

moves.

liquid

in the trap

already

of literature

fall

and desorbed

of the explosive

of this

trap

contents

chromatography. ally

pro-

the operation

of krypton

28

from

because

and subsequent

tion

journal

used

separation.

and Xe

an introduction

performed

Because

usually

of the Kr

through

may

100 are

radio chemistry.

procedures

and Weil

to a charcoal

replaced

These

determination

was

than

air

to achieve

tionary

manner of about

on the separated

In these

They

in case

air

been

adsorbent

gas

gel

techniques

techniques.

source

for

yields

quantitatively

oxygen.

of liquid

The

some

a system

of Peters

of safety.

as a safeguard

from

factors

adeorbed

measurements

analysis.

adsorbed

and liquid

column

such

the relative

by volume

in the work

introducing

have

successively

and used

spectrographic

nitrogen,

when

in this

separation

required.

out a matter 222 that Rn

shown

are

to determine fission

A sidelight point

performed

pure,

in the determination of their abundance in air. A simi35 used for the Heparation of argon, krypton and xenon

later

in an experiment from

gases

traps step

was

99%

not be satisfactory in most 34 analyzed mathematically that Glueckauf

in which

as the final

separations

around

and would

of charcoal

neon lar

that while

which

the

and

the column.

sample

mixture


is

continuously

which

the

uous

passed

sample

flow

mixture

initiated

sample.

of bands

enough

in their

each

addition

in pure

to the mixture of pure

diluted

with

carrier.

sorbed

also

breaks

ed with

all

Only

of other

displacer

emerges

.

(thermodynamically ideal

non-ideal

chromatography

and nonlinear very

large

nonlinear.

amounts

, among

in his

linear

-ideal

insight

into

on page given

are

between

with

Thus

for

a single

occurring,

of his

book.

in the pure

is possible. separations Ilidealll

-ideal

and nonlinear 38 Linear of investigatorfl , 39-46

and by de Vault.

non-ideal

adsorbate

will

case, of the

well

the least

of

qualitative

treats

of the reasoning

accescase

useful 36

in-

be con-

simplest

provides

be

as the

be considered may

Keulemans

~

usually

to be non-ideal cannot

theory

47

and Sjenitzer,

isotherms

likely

account

of

and the process

Linear

however.

A brief

bands

of chromatographic

often

The

com-

be obtained

components

the radiochemist

the nonlinear

same

Eventually

adsorption

treatment.

chromatography

may

by a number

is also

the

ad-

saturat-

of the species

pure

in the

least

a mixture

37

the phases

things.

the processes

112 et seq.

involved,

to the

have

by Klinkenberg

chromatography

other

gaBes

in

component,

is completely

or nonlinear,

treated

first

development,

I’non-idealll.

been

gas

adsorption.

of fairly

by Wilson

adja-

this

case

w-ill be

here.

constant is present ~ection,

of gas

theoretical

Consider

phase

has

separations

to accurate

or

treated

is next

component

containing

chromatography

of equilibrium

stantaneous

sible

non-ideal

Gas -solid

attainment

cerned

were

and effluent

is linear

reversible)

chromatography

which

as to the details

isotherm

from

sample

the column

with

differ

carrier

results

recovery

predictions

as the adsorption

eluent

analysis

of increasing

the

to obtain

adsorbed

adsorbed

by zones

Partial

by pure

In displacement

in order

conditions

frontal

of the least

separated

of course

of an “unadeorbed”

so on until

components.

(diluted

proper

the component

and

in the

from

of the least

and the influent

emerge

Theoretical vary

Eventually

a sample

bands

gases,

“and then

any of the gaees

If the components

separated

consists

of sample

through,

sample

the components adjacent

as a peak

of gas

carrier

components

position. pure

form

in

and a contin-

emergence

components

under

development

column

than

adsorption.

it is possible

If the stream

emergence

adsorbed

in the eventual

increasing

adsorption

component peaks.

strongly

of the sample

of their

Displacement

at one end of the

results

or l’peaksi’

in the order

cent

more

development

eluent)

3)

the column.

is adsorbed

of gae

Elution

column

through

an adsorbent

diameter in some it will

and at conmtant small

distribute

and a fraction

uniformly

( 1 -~)

cylindrical itself

packe”d

into

temperature element

throughout. of the column

so that a fraction

on the adsorbent,

3.8

a cylindrical

As

of

If an ads orbate taken

o of the total a fraction

column

in cross

-

is in the gas o of the adsorbate


is in the gas

phase,

with

phase

the gas

of movement rate

F

and

F ,

of adsorbate

of eluent

weight and

Let

gas .

us call

gae

conditions

may in the

CPa Ge)-l

.

A

same

As

k will

in any element

of adsorbate

(C G -1- U).

In most

simplifies

movement tration band the

to

is

and

C

and equal

is

flow

of total

0<<

rate

everywhere It follows

shape

case

rate

does

will

the

F

The

so that

of movement

-1

rega’rdlese =

Ptot

column is total

rate

of

= q L/Ptot

this

expres-

of “adsorbate

regardless

not change

.

k may,

is the

G Ptot)

rate

weight

V/Pa

be

L

above.

G) >> 1,

the column

that the

and the band

of total

column

1 (q L/C

be

(1 + kA/CG)

space,

defined G)-

In either along

will

case

~ .

of

= (1 +vAe/

Ae/Ge

minute, void

for

fraction

+ vAe)

of

of eluent

(kA/C

factor

to standard

in which

per

~ the

of adeorbate

The

The

in the

column

or

1,

sure

Ge

case,

flow

Ae

Furthermore,

linear,

is the constant

Ptot.

and

to the ratio

In thie

in cc STP

the rate

calculate

gas

Hg).

everywhere

linear

cc

mm

in the column,

flow

may

pres

the ratio

OF . ( 1 + kA/C

instances

OF = q L/kA

of adsorbate.

of the concen-

of all

during

its

points

in a

travel

along

column. In ideal

chromatography,

of a band

ing constant in the gas column

where

of adsorbate

column entering

fa

on the

t is total

is just

nonlinear, formula

temperature

la

is thus

in the

temperature. appreciable

gas

present

and constant

is

By

one

of flow

= OFt ,

approximation the

the above

la

pressure

.

case

if

and the isotherm

discussion

is

of a second

of the first. 19

of adsorbate

phase

strictly

adsorbate

for may

in a band

Pa

t ,

isotherm

if the isotherm for

to tbe

+ vA/Pa)-l

of a linear

Even

in the band,

assum-

introduced

adsorbent

case

exten-

column,

= (q L/Pto~(CG

expects

in this

column,

the

ads orbate

plus

In the

everywhere

entering

concentrations

at ,

in the gradual

down

total

phase

arrives

as one intuitively conetant

results

partial

equating

in minutes

a useful

All

analysis

concentration

in the gas

column,

time

(v/Pa)

frontal at cons&nt

the column.

to the amount

of length

stant

is the

is then

constant

is the same,

sion

this

Hg,

of adsorbate

packed

constant.

that

temperature

X 76o

moves

the linear

of adsorbent.

o = C Pa Ge/(GPa

temperature The

G

in mm

movement

G

law

q is the gas

in centimeters,

gas pressure

sion

at constant

where

K

be

one

ie the partial

v if the isotherm

concentration.

G“Ptot,

‘length

all

laws,

gram

volume

space

to as the Henryle

and is the same

then

is uniformly

void

for

Pa per

= 273”K/(T. will

follows

o times

to the moving

of Hg at column

of column

to total

be constant

be referred

q L/C

C

phase

the column

of adsorbent

e .

cc STP

in cc-mm

be called

It then

gas

available

in the element

in and thus

is just

the perfect

in

resides

the element

the volume

adsorbed

gas

molecule

on the average,

Assuming

volumes

adsorbate

adsorbate

through

Ge

of adsorbent

v the amount

converting

the

a given

o of the time

is

constant.

This

P

is known and cona is known at column

a single affect

adsorbate, the adsorption

as .


In many ner

experiments,

corresponding

ponents which period and

containing

are

helium

Kr

at suitable

stance

1,

length.

for

adsorbates

overtake gence

as is

-ideal

usually

=b(vs– v). a surface covered

of the es.

It will

centrated suit

be seen regions

if one has

sense,

region emerge

earlier

than

concentrations

lie that

Departures longitudinal

from

of the bands

linear

gence

first

then tail

a eteep in which There

ment

-ideal

the

for

where

be

must emer-

fz

is

L = 12k2~kZ

the

–kl) may

be

of

front

25),

ideal

from

the emergence

the fraction v/Pa

conditions tail.

time,

the peak

rate

the re -

low pressure front

of the peak

of the isotherm,

con-

In a prac-

the linear

portions

decreas-

and the more

and a long

k obtained

region

(that is,

appreciable

Assuming

sharp

vs

is hyperbolic,

v increases,

In the latter

1! such

and their lead

peak

front,

during of these motion

tail

will where

of movement

due to appreciable

a less

steep

will

effects

approaches

20

can

shape,

bands one

main

peak

give

might

between

useful

emerging

rigorous

qualita-

Thus

non-

earlier

expect

increases back,

of

in a nearly

cases.

approaches

to more

rates

transfer usually

concentration

s lowly

of chromatography.

mass travel,

in the various

to peak

adsorbate

concentration

two general

their

to asymmetric

As

in which

as those

or non-instantaneous

Superposition

conditions.

adsorbate are

a value

of bands

conditions

of a region main

can

band

of two components

toward

as

faster.

a very

in the gas

fashion.

under

move

“ideality

in broadening

non-ideal

than

of movement

is the time

the isotherm

becomes

increase~

linear

symmetrical

linear,

Thus

calculated.

tive

pictures

length..

emergence

Thus

separation

charcoal,

adsorbate

to estimate

in the

component.

v increases

calculated.

diffusion

result

as

with

used

of the isotherm

approximate

phases

band

T

requirement

be less

+ 12 = L,

Kr with

sub-

the rates

of the first

where

T OIF = T 02F

with

o thus

in a band

is an emergent

tical

with

must

the

adsorbed

column

of

the rear

a long

case.

Thus,

that

a minimal

elution

Thus

band,

in which

the case

v/P

of krypton

over

in

receptacle

of least

the

so that times

adsorbed

length

in the linear

If,

02F,

band,

highly

column

than

separation’by

of the second

of the more

achieved,

introduction

of the band

and

cases

com -

chapter)

is complete,

a suitable.

of the band

to be achieved

of the first

is the minimum

then

OIF

separation

the front

width

length

In such

the length

subsequent

are

For

of the rear

band

is that

into

of the

last

column

of the sample

by elution

temperatures.

the final In the

column two

column

1 (see

to a charcoal

the admission

in a man-

separation

subsequent

Led Procedure

is admitted

at the end of sample

in Procedure

calculated.

Xe

and recovered

operation

be less

with

De@i

and

is accomplished

introduction

analysis,

After

separated

satisfactory

sample

development.

is an example.

Xe

for

to frontal

by elution air

the

than

the emer slowly,

and finally

a long

zero. theoretical

treat-

-


The alent

‘Iplate”

theory

theoretical

species The

treats

platesti

corresponding

distribution

the column

in each

of which

to the ratio

coefficient

as

of their

is a ratio

a series

of juxtaposed

a separation

factor

distribution

“equiv-

between

coefficients

of concentrations

two

is achieved.

in the two phases

for

a substance. The

“rate”

convection them.

The

their

theory

solution

variables)

with

is then

Both

be

highly

radioactive

improved. move The

tail

In the high

Mev

The

tors

theory

much

to move

column

and

as independent

ass umptions,

The

journal

of both treatments. 48 deals with by Glueckauf

that as the

faster

need

It the

per

the nature

of an equivalent

flow of the

rate,

adsorbent

eluent

gas,

relatively

of the

The

simple. will

find

peak.

of krypton

and 1-

of column

development

effifac-

and outlet of the

of the results

who plans

study

to

with

) on various

application

radiochemist

certainly

there.

exposure

COIUmn inlet

the

complicated,

main

irradiation

plateli

size,

Although

etc.

the after

dependence

theoretical, particle

fairly

chromatography

with

by previous 49 gram).

of the band

o is larger

charcoal

that the adsorption

watt-hr

predicts

portions gas,

up”

to use

to be unaffected

up to 1350

latter

of the active and “catch

has

be noted

found

theory

is often of gas

concentrations

the

accounts

by passage

mathematically

to make

of the theory

inter

-

and profitable. one actually

However, build

qualitatively

it. might

was

nature

use

e sting

a system

the

useful.

The

departure overly

assumption reality

simplified

actually

determines

in mind

it with

the equations

from

rare

a bare The

a problem

a minimum given

the adsorptive may

vary

involving

for

for

properties by factors

21

these

are

case

charcoal,

may

and For

prove

a cormiderable

recorded

conditions.

to

written

and effort.

-ideal

or more

the theory

separations,

is of course

of his of two

gas

of time

and the treatment

even

with

paragraphs rare

the linear

conditions

cases,

respects

acquaintance

following

expenditure

earlier

of linear-ideal in most

in some

that these

,only

gases.

who meets

to solve

purpose

needs

to separate

radiochemist

who wishes

keep

tend

eluent

becomes

to practice

this

say

warmed

(doses

as

as

to desaribe

and shapes of peaks when the adsorb ate is a 85 are sharpened and separations as Kr . Peaks

such

fields,

“rate”

pressure,

for

that one article

(i. e. , the ‘fheight such

simplifying

include

the radiochemist

on charcoal

ciency

various

noted

might

thus

electrons

along

such

equations

on movement

that

radiation

processes

differential

distance

earlier

regions

would

event

xenon

involve

gas

One

through

the physical

(in the ads orbate

and axial

given

specifically

of heating

account up partial

essayed.

to theory

effects

sets

equations

time

approaches

references

into

and

of these

derivatives,

might

takes

and diffusion,

earlier

Unless

one

he must from

is

quoted

also values


in the literature. erature

for

The

Kr

temperatures

and

author

Xe

(such

is in fact

unaware

at temperatures

as

- 195”C)

must

lees thus

of adsorption

than

-80°C.

be estimated

data

in the lit-

Isotherms by rather

at lower

dubious

ex-

trapolations. The adsorbent

distribution phase

written

OF

.

q L@~t.

out impairing the of

linear

rate

10 cm/sec

Column

impaired

at very 1 cm

flow large

or less,

fully

(e. g. ,, Detailed

density that

of charcoal

extreme

various

satisfactory

addition,

L/A

Columns above

are

the

to outlet

magnitude partial about

over

the

accessible

O. 1 at 25”C,

over

pressure

of eluent

constant

desirable As

atmospheric

mm

Hg.

a certain

v/Pa

for

= k

which

generally will

ranges of

.

column

one may

at which

the band

velocity

of an adsorb

suitable

retention

time.

ate

22

column

in the case

several

Thus

for

guess)

of interest

with

Kr

at

some

is such

decreasof

1 mm

gram

at -195”C. find

are

temper-

orders

per

in

of a linear

rapidly

vary

generally

flow

pressures

adsorbate

the

v in cc STP

100 ( a rough

chromatographic

a given

increasee

often

of inlet

difference

the desired

by adjusting

One

as possible

that the ratio

operating

velocities”

system.

sufficiently

and with to 760

in

In

his

to maintain

the values and

flow, close

10.

that higher

temperature

3 at -80”C

an inlet

always

of

required

velocities

charcoal,

a factor

it follows found

constructed

ranges

r~tio

of charcoal,

the bulk

it follows Band

wide

O, 2 gm/cm3,

of

success-

A*

to be as nearly

Adsorption

and band

pressure

a typical

over

chapter).

about

as possible.

is

respect.

is a constant.

ing temperature,

unity

function

gram

the desired

generally

been

one has

and it is thus

speaking,

varied

i. e. , by changing

isotherm

of eluent

varying

once

nearly

pressure

roughly in this

~tis

column,

out outlet

with

O, 5

per

with

is also

by only

varied

to sustain

be as near

conveniently

ature,

rate

length

differ

operated

Thus

of the

column,

preferable

most

often

flow

length

inlet

a given

will

pressure

pressure

between

are

most

the linear

along

columns

at the outlet.

wishes

range

is not conveniently

atmospheric

pressure

in the

in last

serious

value

are

have

for

is not par -

Efficiency

diameter

with-

of the order

without

diameters

be

value

rates

the optimum

flow.

of the may

at will

parameter

is not a rapidly

given

column

flow

this

Column

centimeters

lies

of L/A,

be varied

of two or three near

1,

in favor

movement

an optimum

Linear

linear

efficiency

generally

values

rapidly

Procedure

may

though

decreased

of several

of band

predicts

by factors

diameters.

Again,

and columns

theory

the column,

less

be heavily

rate

quantities

typical,

drops with

column

diameter, used

Thus

be varied

than

generally

so that

of these

be considered

efficiency

linear

all

through

and may

increased

around

of gas

will

systems

efficiency.

might

critical

effect.

gases

Not

column

flow

titularly

of rare

in separation

Hg

are Thus

for

temperature

as to give

a


In addition achieve

initial

improve

sample

,9eparatione

proportional roughly

A few

or borderline,

ditions

may

system.

with

In the

latter

be made

caee,

length

(C G + vA/Pa)written

troduced

coal

column

centimeter

length.

gram

of charcoal,

as

Detailed

Procedure

radioactive length

margin

foregoing

Kr,

of safety

variations the gas

from entering

partial

thus

isotherm

however, of a very

being

of

of

Xe.

values

10 greater

Let

Under

= The

of for

using

centimeters

sure

a f3-y

1 is about

length

of

Kr

this

form in-

length.

If

introduction,

v

are

Values experimento a char-

in the influent of charcoal

known

sample survey are

gas

per

meter

25 cm,

neighboring

in the

rare

tem-

in

on bands The

of

actual

calculations

pressure sample

of temperature

of the two.

this

col -

a considei-able

that the above

conditions

at

introduction

noted.

as the partial

us assume

23

h

be re -

of adsorbate

is introduced

5 grams

uncertainties

the heavier

may

these conditions is 10 cc STP 100 cc STP Kr gin/cm] = (10 cc STP Kr/gm)(5 an value of v used above is strictly

and

v for

this

temperature.

in air

t~ a typical

same

= (q L t/Ptot)

unit column

of band

few

the

of

of width

under

lKr

for

margin

as proposed.

1.

is not experimentally

allowed

con-

can probably

la

sample

at column

pres

Kr

Procedure

the column.

pressure,

a factor

of

corresponds

in Detailed

per

contains

run to run in suâ&#x20AC;?ch factors

100 cc STP

about

1,

widths

used

column

at

as

cc STP

during

of Kr

the partial

arriveq

necessary

-

of the

in a band

be tried

earlier

the total

is known

introduction.

the adsorption The

gae

one

is unsatisfac

a suitable

= (q Pa t/Ptot)(vA/L)-

100 cc STP

The

given

operating

G G << vA/Pa

the calculation

and that

at the end of sample

estimate

tains

that

Hg.

where

eimply

If the adsorption

perature.

umn

â&#x20AC;&#x2DC;C,

at O. 02 mm

given

is constant

for

Assume

at -195

constant

2 cm

required

was

la

prove

on the adsorbent

if the isotherm

quantities

accessible.

cc STP

is

may

in es -

are

runs.

case

as

length

of adsorbate

be determined

tally

per

by the

pressure

trial

band

approximation

divided

which

few

the usual

that the band

the partial

of other

changes

with

might

are

construction

of sample.

the system

length,

of a very

and for

1,

retention

perform

and/or before

to be satisfactory

usually times

column

operation

parameters

to

increases

one might

directions

initial

of an adsorbate

to a close

it is obvious

is

further

on the basis

which

length

will

retention

broadening

that the proposed

appears

to column

band

column

length

since

chrornatographic

column

regards

adjust

in column

while

in the indicated

as

respect

The

may

then various

may

also,

calculations

indicate

be adjusted

particularly

small

length,

of a proposed

If the operation

safety,

Increases

of prior

calculations

one

components

the column

examples

If &e

velocity,

retention.

the performance

below.

band

of several

to L, 1/2 L .

as

timating

tory

to adjusting

gases

are

Thus

it is

of

and Kr

also

in conâ&#x20AC;&#x2122;

and rare typically safe

to say


that

Xe

till

be initially

retained

Beyond

this,

column

will

be attempted.

able

vS,

the cc STP

to

no statement

100 cc STP unknown,

per

concentrations

Having

retained

separation

ties,

and thus

most

conditions,

to

Xe

with

for

most

length

Xe

may

it is

discussion. be less

than

umn

a few

is,

all

However,

but a few

an unnecessarily in order mated

to bring

moving

Kr

retaining release

time

than

for

in the mode

adsorbed

gas

in other

minimum

the band

width

of xenon,

under

would

be eluted

have

so one raises

the column

column

A sample

development

intro -

pure

a column

the

would

xenon. be take

temperature

calculation

appears

will

off a col-

leaving

left

of Kr from

con-

length

at end of sample could

minutes.

column to the

of operation

krypton

the e lution

of the

be sufficient

refers

be useful

for

with

minimum

“2”

the calculated

Elution

off in a few

earlier

may

Kr

-

under

allowing

usually

k~) where

of the krypton

even

than the purity will

column,

the adsorptive

of the

case,

at - 195”C,

Browning, and

them

Xe

and Ackley

fission

until

products

radioactive

to the atmosphere. be designed

of the theory

used

ence

to a more

ideal

approximation

nevertheless .of the

in general

given

2,

of the less

during

gas

of esti-

in the

second

below.

Adams,

system

the Kr

retention

example

time

are

rare

of magnitude

the purity

fractions

gases

than

introduction.

long

involved

of the

As

obtained,

tailing

component,

rare

percent

the end of sample

of

is the fact

portions

an order

easily

of both

linear-ideal longer

compar-

and by the adsorption

small

by about are

the equation

with

width

are

of each

be attempted.

to be better purity

adsorbed

in the

percent

may

L = 12 k2/(k2–

use

on the

is of the order

complication

the adsorption

Kr.

Xe

of the isotherms

serious

in suit~bly

of this

is greater

the band

That

fore

less

of little

duction. only

,“ because

Although

If k2/kl

Xe

differ

be expected

1!111 to the

nections,

and

separation,

here

which

of the other,

development

The

and

discussed

portions

separations

to Kr.

Kr

of

of air.

velocities,

However

purposes.

and

Kr

sufficient

to achieve

more

the

the band

respect

The

by the presence

by elution

‘Wiling”.

v being

of

a monolayer,

A more

quantities

than the band

disposition

on the adsorbent

be affected of large

of

to form

of charcoal.

their

respect

values

ly nonlinear.

certainly

band

The required

gram

on the column

narrower

as to the actual

but definite

that at these will

in a band

rough

as accurately

detailed

from

have

of course

a useful

predictions

with

is

experiment.

24

reactor sufficiently in this

before

trial.

for

off-gases

decayed

reand

to permit case

Some

“that the

discussion

given

of the theory

illustration

on a system

necessary

as possible

not be satisfactory

provides

reported

homogeneous

the system

treatment

would

recently

species

It was

in designing

50

in the article and a refer51 is noted. While the linear

for of the Fission

use

in design

calculations gases

in this

case,

it

and a comparison

contained

in a stream


of oxygen

flowing

and 25 “C) Each

were

series

Bisted The

at a rate passed

of pipes

charcoal

was

is

thus

l/(bulk

In the

O. 5-in.

1. 50/k

coal

pipe

6 -in.

in the

column,

OF is thus d~8i~:d

=

0.0104 ) of k given

velocity.

retention

times times

and lengths

times

for

were

observed

per

percent

gram

of are

of char-

of the adsorbate

section

the length

equals

is thus

and

TR

O. 08 for

Kr

for

The

Xe.

This

nature

of pipe ~

+ values of

calculated

Observed

article

of Henry’s

for

(in cc STP

pressure).

respectively.

on variations

above

= ~ + ( experimental

The

163 days

liter/rein.

helium TR

write

law

re-

also

con-

constant

of carrier,

estimated (in rein,

the last retention were

Kr

flow,

43-cm.

with

partial

charcoal

).

k as

Using

#

estimated

0.08

for

26 min.

2. 1 and

20 min.

Observed

Kr Kr times

, respectively.

25

and

1.3

T-

K

for

of O. 6 or

-80”C.

Emer-

stream,

=

,

(bulk)

To

emergence

is

cal-

of

1.6 we

density

column 43 gmX760 1600

Xe

time

and

in the tail

temperature,

1 gm/cm3.

deof about

in the case

column

Thus

were

the trials

the effective

retention for

and

times

at about

to be 43 cm3.

the calculated

time

and 25°C

flow

actitity

in all

separations

columns

in the exit

retention

In the article

is

O-C

Xe

gases

eluent

1~0 of peak

obtained

for

rare

of 25°C,

and

were

column,

= lA~t/q.

.aeometricallv

example,

maximum

and

off using

helium

radioactivity

approximations

= L/oF

of the 40 to 50 mesh

temperatures

separations

the linear-ideal

and eluted

16 or 43 cm,

of 5,

peak

Satisfactory

may

ima

equal

in cm/gm

formula

Xe

and

by measuring

breakthrough,

recorded.

Xe

Kr

of charcoal

, and operating

liters/rein. peaks

from

space

a few

of the adsorbent,

end of a column

diameter

gent

20.4k

and the

section

of the simpler

Hg adsorbate

and 60 days data

only

time

for

mm for

of void

and the adsorbent used. 52 recently reported studies of 85 and Xe133. The tracer tracer Kr

using

at one

is

in each

of L/A

and Grandy

on charcoal

ume

of the pipes

pipe.

of the charcoal

L/A

125 X k (days).

1.3

per

content

and coni. d.

of krypton,

posited

culate

10 days

volume

Values

in each

) =

10 days

charcoal

density

the ratio

Use

retention

about

experimental moisture

Koch

1.6

thus

were

temperature,

1 -cm

are

charcoal

are

interesting

time

X 105 X k(min.

gram

that

phase.

Total

bulk

1 cm3

calculate

in the gas

in the article per

roughly

Retention

1.80

adsorbate

pressure

one may

justified.

k

is

charcoal.

l-in. pipe, and O. 00792 for 6-in. pipe. 1000 cm3/min. X 1. 14 cm/gm . = Xk 60 = O. 375/k in the ~%.~ipe and O. 0104/’k

OF

there

resides

by band

tention

As

containing

and 60 ft of 6-in.

internal

in cm2).

pres sure

for

= qL/lAPtot

Similarly

pipe.

in the column

tains

OF

of pipes

pipe,

packing

-section

1 atmosphere

lb of activated

l-in.

the total

O, 285

(at

series

at an ‘average uniform

pipe,

in cm/min.

in the

From

)(cross

O. 5-in.

minute

of 520

40 ft of

one arrives

density

1. 14 for

a total

pipe,

Aaauming

per

two parallel

contained

at 25°C.

of charcoal

to O. 69 gm/cm3. pipe

through

of 40 ft of O. 5-in.

weight

of 2 liters

1.6

volmm Hgxk . cm’/min

min.

of the peak

and the max -

.


The

emergence

by means Keulemans

discusses

technique

involves

changes For

components

radioactive

various

gases

methods

another chamber

of the various

by charcoal

will

in certain

adsorb

interfere

to slightly

of oxygen xenon

are

chemically

from

the gas

of some

from before

the

thus

introduction

from

the mixture

rare

gas

fractions

of convenience

after

gasee

before

their

charcoal

possible

should

gel

has

specific

those

of activated

Adsorption areas

charcoal 28 There

mentioned).

may

adsorption

This

choice

and

are

be separ

-

be removed difficult

to

it (e. g. ,

either

or from

may

amounts

by adsorption

to ‘poison’

their

large krypton

usually

always

they

rare

be removed the

be made

separated

as a matter

experiment.

is the most

one.

Silica

53, 54

the chromatographic

krypton must

since

than

from

before

hydrocarbons materials

elution.

in the particular

Though the only

of rare

it.

and nitrogen

If only

air

from charcoal and their accumulation tends 50 oxides of nitrogen, HCl). Most impurities

water,

other

of argon

from

to charcoal

through

oxygen

chemically.

to separate

Certain

used detects

leaving the column 55 sort to detect the

argon,

separation

light

widely which

impurities

while

to remove

difficult

moBt

gas.

the column.

chromatography

krypton. its

leave

accomplished

or by distillation,

ated

the gas

a counter

Thus

be detected

gae es pas sing

is to paea

extents,

is very

The

(katharometer)

or near

as they

may

of the effluent

method

it is not necessary

Methane

on charcoal

cell

y of the effluent

cases.

is best

of interest

separation.

remove

different

and nitrogen

a column

property

of detection,

components

Ln separations gases

from

in some

conductivity

conductivity

an ionization

activities

change

a thermal

in the thermal

through

been

of various

of the corresponding

less (its

generally

useful

is a very

general

than but of the

use

adsorbent property

same

in the adsorption

ie in particular

one

it is by no means of surfaces.

order

of magnitude”

of radon

other

class

has

as

already

of adeorbents

which

should be mentioned. These are the so-called ‘Bimolecular sieve” ma56, 57 terials, now commercially available from Linde Air Products Company, Tonawanda,

tion

New

properties

Linde

York.

are

Molecular

Thue

uniform

as those

of many

sorption

for

the adsorbent Because

CaO.

size.

diameter, activated

a given

gas

and in fact the pores

A1203.

peculiar

medium

(and molecular)

these

to some

(activation)

porous

4 and 5 angstroms

tion.

is

Their

of hydration a highly

discussed

Sieve

alumino-silicate. water

Actually

are extent

occurs

with

results

and the 4A is that little

in which 4A and

is strongly goes

have

in which

Specific

dependent

through

change the pores

been

adsorption

26

Sieve

in the are

surface

structure.

pores areas

The

at nearly are

lattice

of remarkably

have

on the degree

occurs

is a“ sodium

of the original

reported.

a maximum

such their adsorp23 Thus, the 5A

removal

5A materials

respectively. charcoals

and as

by Dushman.

Si02,

property

The

zeolites

of rotighly as

extent

great of ad-

of dehydration complete

of molecular

of

dehydradimen

-

,


sions,

the

size

adsorption. tive

of the adsorbate

Thus

to one another

sible

illustrate

ane.

On a charcoal

water

considerably

and charcoal. quite

close

ent.

in

ents

It was

keeping

be

literature

IV. The of target

clear

SAMPLE radiochemist

solution

may

produce

likely targets

complete

initial

handle

than

removed H3P04 product.

large

Sieve

(27, followed of all sievell

of the peaks

positions

sieves”

were

using

or mixed samples

absorb-

is worth

radiochernical

procedures

also

Aluminum

as

for

rare

heavy

C-RLERS

gases

the target

Since

the recovery

of solution,

gaseous

from

elements

bringing

products

regards

of the

targets

products

volatile

is

are

a variety

in which

material

acid.

drops

containing found

Thus

of 30%

caustic.

nicely

method

gases done

will

with

uranium

H202

of solution

to the solution

of aluminum.

27

may

often

acid

Methand

easily

again

re -

extreme With

simplify

choice

are

simpler

dissolved

with

targets

for

of

matters.

If the

is to

in con-

and the HC1 fumes

be useful

of small

gases

the feasibility

Solution of uranium in warm 59 and hydrogen is the only in 6N NaOH,

a

procedures

of dissolution.

acid.

is

added

into

to be desired.

encounters

with hydrochloric

satisfactory

dis solves

a preliminary

evolved

fission

of, the rare

solution

products

usually

usually

solution

nitric

a few

This

from

radiochemist

from

with

been

to recover

WITH

for

containment of metal

in a trap

amounts

and the krypton

the solution of spent fuel elements 55 certainly exemplify the most therefrom

that the

those

or as

which

of the two adsorb-

from

such

need

in principle.

to be met

by hydrogen.

er foils

positions

-

-meth-

of Bimolecular

percents

gases

of any

usually

tractable

gases

HC1 with

has

impoe

that the separation

“molecular

of rare

EXCHANGE

the volatile

the products

centrated

ucts

be used

the more

the small

Solution

rela -

off together,

of the peak

AND

suitable

in the literature

problems

available

have most

method

from

of the rare

covery

relative

average

is unaware

may though

#my

reported

came

adsorbent

a weighted that

off first Molecular

found

the weight

SOLUTION

materials,

be effected’

which

that the

of

different

to date.

occurred.

must

then

a mixed

separation

author

came

On 5A

by using

possibility

in the

The

It was

found

to obtain The

in mind.

in the

further

useful

the extent

be quite

and separations

and krypton

by using

calculated

adsorbent.

could

the nitrogen

but together.

by the methane.

to those

may

on charcoal,

the nitrogen

be achieved

the mixture

the pure

(20 “C), later

at 20 “C,

could

influences

species

be feasible. A recent article gives an example 58 The mixture studied was nitrogen-krypton

column

later

gases

strongly

of two

the adsorptions

considerably

by weight)

three

ods

may

the point.

and methane

has

from

on charcoal

will

molecule

the ad~orptions

simPIY 9270 gaseous

no gaseous aluminum clad

prodcatch-

in relatively


Solution the rare The

gases

former

their

must are

with

or adsorption

and active change

from

simply gases

in the

cooling

rare

are

with

.

As

diffusion

phase

and heating

removal

of the tracer

least

complete

exchange

the

gases has

from

been

solutions

studied

tracer

xenon

moval

are

lives

in solution

ium)

for

have

first

hydride

are

chloride

diffusion

negligible. in place

ium

metal

les~

than

containing 62

most

ameters in

before

solution gaseous

might

of the heavier

metal

lattices.

I,microcracksll

fission

products

temperatures

and cracking

rare

may

gases

are

of rare

often gases

xenon

uranium

removed freshly

from

from

in aqueous

AgC104

cupri-

is generwith From

is no detectable of rare

than thus

uranat

begins,

diffusion

as the atomic interatomic

be mainly

the

loss

gases

Negligible

temperature

by

and

potassium 61

is desirable.

there

di-

distances

through

lattice.

been

reported

neat method for removing rare gases from 63 recently. It is based on the fact that long-chain

salts

of heavy

metals

(more

rapidly

emanate

gases

rare

gas es quantitatively

can be swept

from

28

solutions).

be

uranium

be evacuated

evolution

of may

the hydride

at low temperatures

if this

uran-

metal

A particularly

than

other

decomposed

generally

larger

re -

on the formation

Thus

must

the

helium.

of the sample. at room

for

of

with

of hydrogen.

metals

commenced

be expected

Movement in the

from systems

is

At higher

by swelling metals

gases

dissolver

depletion

of various

in saturated

amount

and ex-

out of solution

hydride

dissolves

as helium

half-

uranium

then

“~f rare.

with

less.

from

of uranium

of a small

of rare

Thus

1000”C.

accompanied from

of uranium

Removal such

the

or at

species

(specifically

from

1~~ or

consider

solution,

that the

Efficiencies

and the xenon

Uranium

the evolution

swept

ex-

by alter-

of diffusion)

gas eous

targets

of xenon to be

solution

satisfactory.

with

The

or

often

also

gases law

(as

and half-times

Thus

from

Loss found

carrier

time,

thorough

carrier.

Fick’s

effective.

gases

Amalgamation

and boiling,

boiling

target

was

with

are

slow,

theoretically

minutes.

is also

to the hydride

method.

expected

minutes

rare 60

studied.

inert from

exponential

solutions

at 300”C

converted

ally

than a few

been

as

of a few

removing

the hydride

some

is

through

gases

The

of the carrier

the target

with

the rare

mixing must

and

any chemical

states.

miting

One

from

of carriers

With

relatively

gases

(starting

found

of the order

the clear

methods

by bubbling

It was

of more

Boiling

of dissolved

theoretically

perimentaUy.,60

gases

to venting.

chemical

by convective

of the system). active

in which

before

phase.

physical

are

insured

prior

be effected

between

processes

of parts

complete

stream

on the gas

complete

is usually

or a system

as introduction

may

of exchange

one of achieving

gas

gas

work

gases

performed

rates

system

the effluent

in quantitative

operations

is

out in a closed

the active

no problems

problem

nate

removed

is preferable

exchange

one has

be carried

targets fatty

has acid

and very

rapidly

Removal

of more


than

997D of the 3. 9-see

Htearate

targets

pendent

in fission are

of carriers.

yields

are

of no primary Rather,

yield

The

of gas.

interest

yields

experiment

and one point to reduce

previously

used

procedure

are

ual pressure certain gas

with

partial

behind

to the amount

es to increaHe find

that his

a lower procedure cipal

yield

limit

100

specific is only.50%

losses

Method~ veniently

which

divided

of the type

mentioned

amoonts

losses

a trap

in a resid-

the

and bear

if one obtains

20 cc STP

or a

in which

of ga~

18 cc ST P),

one may

have

by the usual half - life

Muller

been

Incorporation

of the

or” proportional

no

90’-7’. yield

experiment

wish-

of carrier

he may

There

is

essentially

u8e without

modification

(where

are

the~e

of the

the prin-

rare

counter:

with these problems 64,65 Only a few

time

course

the moat

favorable and often

geometry necessary

emit as

means

gas

choice

of this

be de-

will

of counting

of radiation,

in the filling

be made

of absorption

losses.

of low

of activity

isotopes).

of short Both

range Geiger

(soft

beta-emitters,

and proportional

29

involves

one in all faced

to standard

here.

activities

in the assay

levels

of

of a Geige~-

experimenter

be referred

gaseous

level

desired,

The

must

comments

be con-

will

technique

and filling. in detail

may

of method

and energy

of information

use

activities

and absence

radiations

radon

construction

efficient

rare

g as to be counted The

the first

ACTIVITIES

The

of kind

and type

of counter

subject.

to count

considerations

of activity,

GAS

categories.

the problems

on the

R-E

used

several

termined

1)

COUNTING

into

activity,

such

than

of carrier

one finds

than

losses).

V.

which

rather

only

to

of a certain

and in a later

by using

(10

from

Thus

cc STP

by condensation,

of cc STP

added.

when

of the

in terms

stream

of carrier

experiment

less

in a transfer

of carrier,

activity

to the amount

to reduce

gas

percentage

from

in mind

usually sub-

of so many

that most

in terms

are

interchange

be kept

addition

to perform Actual

to something

happens

the

of interest need

considerably

in the exit

cc STP

gases

be expressed

losses

of carrier

with his

are

. concerning

in terms

should

volume

of a gas

of inde-

complete

vary

‘It often may

in studies

one will

expreseed

may

in a given

These

in an experiment

.

rare

of c,arrier

which

pressure

ia condensed,

relation

success

of the type left

are

amount

used

and c~nveniently.

in particular

the

Uranyl

gases

gas

assuming

needs

required

it desirable

for

much

accurately

ones

stearate.

to be made

added

of how

barium

were

rare

comments

of carriers

from

catchers

containing

a few

operations

and activity.

achieved

stearate

by consideration

counting

was

chains

perhaps

Amounts

determined

219

and barium

yields There

sequent

Rn

This

is

texts of

as a result

It is thus

of

desirable

or of active

species

or alpha-emitters counting

for

have

been


used,

each

having

associated

with

proportional times

samples

pulse

vary

voltage

plateaus.

This

but is more with

with

counting If absolute effects

(electric

depending

constructed of field

with

tubes

General theoretical

sion

ically

except

using

ization

aliquots

tubes

Positions brief

may

lengths,

per

till

timum

be determined

construction especially form quench

will

(particularly from

negative materials

unit path

highly

probably

may

using

Some

any

in Ros si and

determined

and thus

find

some

by his

empir contechion-

the wall

effect,

variety

saturated

30

such

as well Purity as

and a suitable

factors

as

in the literature,

experimentation

counting).

A large

gases

on so many appear

electronics

species

Light

of the rare

depend

in proportional

be used.

be

that the average

length,

examples

electronegative

ions , is important.

and

may

an approximate

be found

generally

(remembering

of plateaus

but the researcher

filling

of the filling).

be made

here.

may

effects

by installation 66, 67 voltage.

including

are

end

sample in two tubes of identical 68 and wall effects by a similar

diameters

and shapes

discussion

fillings

effects

walj

Counters radial

type

counting. for

and for

at the proper

effects,

this

absolute necessary

is

with

the same

in the counter

the field

corrections

End

of the same

radiation

are

detection.

and held

and composition

fillings

quench.

which

and wall

effect 9).

of different by the

preclude

over

for

vary

heights

to calibrate

to attempt

of the radiation

time

and proportion-

do pulse

easier

es-

more

multiplications

than

extremities)

required

the wire

different

on pressure

Counter

with

of wall

for

produced

depends

volumes

Appendix

by counting

struction

ionization

Geiger

and to reproduce

than

for

by using the 55 (as Fe

radiation

gas

corrections

at the tube

of end effects

234,

it is much

is lmown

unknowns,

of ion pairs

derivation (page

Staub6â&#x20AC;&#x2122;

specific

as

region

activ-

is to be obtain-

as by running

to both

gas

be found

as accurately

levels

the latter

usual

as say

distortion

active

at least

in this if very

the rare

accuracy

monoenergetic

be attempted,

concentric

discus

As

whose

count~

must

some-

and the

important

method

is applicable with

are

if the best

suitable

if one may

dead-times

containing

some

in the proportional

must

number

and

and discriminator

in as saying

field

on the

the minimum

some

region.

counting

fillings

equipment However,

performing

savings

conditions

accurate

samples

conditions

counter

method

voltage

in the Geiger

of counter

nique

with

since

Since time

can be reproduced

voltages

rapidly

The

counting

observed

al counters,

smaller. case,

electronic

expensive,

of usefulness

of activity,

in composition

to set high

consuming

are

The

and less

range

levels

in any

be run.

conditions

height

x-rays)

more

losses

reproducible

Counting

a greater

high

slow

must

of course

tablishing

is simpler

do have fairly

is relatively

ity will

ed.

to count

and disadvantages.

counters

coincidence

manner many

Geiger

counter~

wish

resulting

advantages

necessary as by his

as

op-

counter

of materials,

oxygen

which

of polyatomic

hydrocarbons

to 68

tend

to

gaseous are

among

the

-


most

copmon.

Detailed

It might

Procedure

purification. (roughly

At Lawrence

krypton,

junction

with

portions

this

gas,

When

low

level

liter

in

2) levels

it may

External

are

be

sion

tubes

on one

counter

lower

counter

best

accuracy

permanently

available

thin-walled

for

e~timated mg/cm2

counting counter

100 to 200 These The

disintegrations/minute

counters counter

were

was

the aliquot

dilutions

with too

used

sealed

reducing

itially

Kr85

inert

of the carrier

with

sample are

which

was

For

higher

re-

being

respect

such

con-

efficiencies

to be described over

the use

The

effort

next.

of ‘! fixed

in rapid

the container tube,

succesin a

which

must

with

volumes

the gas

counted

may

resulted

of 3-10

be accurately

system

by a seriee

cases

where

in an

cc and 30

activities

as

low

as

assayed.

in the aforementioned

a vacuum

for

factors

specific

could

region

for

as in commercially

glass jackets (Radiation 72 used this type of tube

jacket

cc STP

described

with

counting

and absorption

into

gases,

to fit the shelves

Reynolds

with

rare

Practically

counted

71

concentric

samples per

per 85

reduced.

counting

in the Geiger

permanently

be

).

efficiency

of 5-20~0

Thus

Kr

In very

geometry

tubes

may

considerably

geometry

efficiency wall.

70

method

samples

Illinois).

Combined

whose

containers

solid

tubes

Skokie,

d/m

assay

geometry:

of this

of samples

counting

counting

Laboratories, ‘ 85 counting Kr .

proaccu-

beta-emitting

geometryif

to a thin-walled

Counter

smaller

necessary.

and overall

advantage

is thus

wire.

in’ con-

to allow

4200

krypton

reproducible. volumes,

plated

and

carrier

container

by constructing for

in calibration

For be affixed

(say used

for

1958 should

where

reproducible

the ‘rfixed

is that a series

ordinarily

be expended

with

One

or energetic

small

the main

sodium used

date.

or

is accurately

than

with been

at the

and in 69

background to use

in fixed

to fairly

seen: below

geometry”

this

in a thin-walled

counter

limited

isopentane

is desirable

/min.

at an, early

counting

better

to

no further

counted.

the atmosphere.

be necessary

be counted

generally will

disintegrations

for

according with

to be counted it should be borne in mind . IS now appreciable. In the Paris region

of gamma-emitting

to .a thin-walled are

are 85

drying

Hg have

generally

of the aliquot

from

the atmosphere

may

tainers

1200

after

up to 20 cm are

purified fillings

technical-grade

cm Hg pressure

Kr

and correct

of activity

the gas

As

was

of

removed

work

from

level

xenon

counter

ae quench

Plateaus

measurement 85 of Kr

1954

used

low level moved

used

levels

of krypton

in carriers

is

but several

that the atmospheric

and

Laboratory

pressures

quench.

of rare

that krypton

in proportional

Radiation

and xenon

and convenient

this

used

20 cm Hg pressure)

Argon,

rate

be noted

1 are

work.

and provisions of expansions the activity

for and

is in-

great.

At Lawrence ing and following

Radiation the decay

Laboratory of a variety

31

these of rare

same

tubes

gas

activities.

are

used They

for are

countsuit-


ably

filled

permit

and used

decay

particular taining

ing

curves

equal

used,

volumes

.

counted,

sion,

but overall

efficiencies

Each

circuitry,

systems

.

and the

which

switching

arrangement

resolution

of fission

and tedious,

walls

to remove

the

softer

accurate

determination 88 the counting of Kr .

tering

definitely

roughly xe135

decay

curves

that the behavior

formation glass

decay

reached

decay

was

1s “ expected

decay

curves

farther

for

but conducting

is to be counted It was 10~0,

of”interest produced

stated

tail,

in some

suitable

target

in which

he can

in a U235

target

the

same

tor

k in this

tube

later

familiar

and case

for

a known determine

irradiated

efficiency

The

manner

counting

no different

neutrons,

.

provided

counter

simpler

became Xe’33

and assumed

the

18. O-rein.

immediately of local

The for

glass

it wag

with

after

charges

in irregular

sample

matter

was

containers

its on the

deposi-

the internal

the gas

of these

that no effort

accurately.

undoubtedly

to statistics always

that the

be noted

in subsequent

are

are

enclosing

As is diffi-

mg/cm2

and

associated

to be ionized

surface

85m

Kr

200

-

and a

walls

of

resulted pursued

in which

in

no 88 Kr

geometry.

above

efficiency

essentially

a U235

walls

in high

but it should

the actual

dures

a conducting 88 Kr conforming

from

succes

to be counted.

the scattering

85m

that accumulation

to provide

a stop-

point concerning 88 of Kr exhibited s cat-

in the same

curves

hypothesized

As

into

special

curves

the Kr

statistically

the R~8~

“ was It

that

with

and permit

up one

expectation.

in the range

be plugged

in rapid

4. 35-hour

by absorption brings

be-

is provided,

special

of the jacket containing the gas was resulting 88 of the Rb on the walls. It was found that silvering

tion

are

betas This

char -

to and removal

samples

walls

the jacket

of

.

the decay

behaved

As

73’74

with

noticed

of the Kr

daughter.

Rb88

from

still

is fitted

of the tube

purchased

con-

radiation

may

be plugged

were 85m

statistical

when

may

selection 88 Kr

are

which

attachment

2. 80-hour

88

It was

beyond

statistical

Kr

activities

of many

the

y counter

of the beta

a base

easy

With

and

of a mixture

satisfactory

to the jacket

of tubes

rapid

of Kr

various with

to allow

a number

tubes

gives

the counting

allows

a few

for

losses

activities.

Hg pressure

the energy

connection

joint

product

with

coincidence

higher

10 cm

is fitted

To facilitate,

into

initially

with

vary

tube

ball

to reduce

and isopentane

losses

a panel

cult

from

filling

of argon

and ground-glass

vacuum

counters

Absorption

by Reynolds.

the counting cock

to be taken

electronics

acteristics

quoted

as proportional

with

counters

to most rare

are

and the same

of unknown

of fissions

the number thermal

counting

conditions

involves

the number

).

counting

samples.

Thus,

The

has

counting

order

nuclide are

re-

proce

-

contexts

counts

the Kr

been

induced which

by counting

f,

each

fissions

calculation

of fissions

for

in other if one

of the

to determine

conditions

Such

of such

neutrons

was

made

calibrated

radiochemists

gases.

number

counters

is ordinarily

and 88 from

by thermal occurred

the Kr 88

(using

of the calibration

the activity

AO,

of Kr

fac88


extrapolated

back

to a suitable

zero

time(

the midpoint

of the irradiation

for

sufficiently ehort irradiations ), and a suitable aliquot factor. Thus, f = kl X Ao ~ cc STP carrier = k X AO X cc STP carrier/POoC. The actual volume V/ 7 6

‘o “c x

V

of the counter

inclusion

for

calibration

is

fission

Ultimately,

accuracy

ers

the obvious

has

and that

due 3)

to the time

of rare

in a glow a glow

potential

tube

moves

high

gas

has

Indirect

study

be taken

of the feasibility

gas

fission

coaxial could

product

with

distance the

stearates

(from

techuiquee

may

gases

themselves

decay

products

gas

from

the wire.

rare

be useful are

too

chain ,of rare

gases of rare

where

days

their

volts

gas

dc

maintained on the

Heating at room

re -

temper

-

and radia-

daughters: cognizance

through

were

in

of some

activities

themselves,

gases

yields gas

emanate gases gas

short-lived

of reasonable

collected

hundred

Rn 222).

for

through

gases rare

are

of the half-lives

and the daughter

Fractional

products

are

rates

of daughters

which

retained in studies

Trace

co”unting

performed

should

their

daugh-

in which

rare

coilected on a negatively charged wire 78, 79 Rough half-lives for the rare gases

stream:

flow

for

each

as the cathode

and the discharge

range

for

discharge:

pressure

A few

count-

calibrated

a tube

used

of the gaseous

experiments

E were

microns

“helium).

g as activities

early

daughter

amounts

the decay

activities

(in the percent

of studying

some

a moving

along

relative

where

Thus

be obtained

rare

discharge

rare

in a glow

gas

can

of gases.

or foils

and retention

of counting

requires

manipulation

hundred

air,

a glow

of rare

not a method

activities.

a few

proved useful 76, 77 .

activities

Although

ter

with

deter-

one

be separately

on wires

but it is quantitatively

technique

of rare

accurate

a direct

the uBe of these

time

on the cathode

(nitrogen,

surprisingly

The

4)

along

Deposition

the activity,

ature.

g ases

to cause

minutes.

is

for

must

solution

calibrated

While

purposes,

counter

It is often

been

involving

in a short

be deposited 5. chamber. “ Tracer

“is applied

cathode

that each

saves in the

the target

already

performed.

all

may

the discharge

a few

been

and its

determination

of measurement.

have

practically

cases

of the carrier

experiments

of samples

of rare

discharge

discharge

to support

for

required

gases

actual

f by assaying

counters

have

in most

pressure

of fissions

must

drawback

without

the temperature

of course,

a number

Deposition

amounts

factor

which

in targets sufficient

counting

sample

~rom

for

information

the measured

the number

of fiseions

achieve

tions

O°C

product

(e. g. , M099). mination

for

Po”c to

to determine

some

no useful

work.

corrected

possible

provides

in the counter

considerable counter

jacket

very

to count,

half-life

33

for

have

activities

leaving

counting

activity

rapidly) the

also

as a function been

found

studied

in heavy

of through metal

and on container walls 63 Such deposit.

stearate

is inconvenient

or where

but the immediate radiochemical

assay.

or

the rare subsequent


5) gases

Rare

have

main

g as

been

such

that

light

output

tion

denmity). 6)

which

The

have

to be

counting: satisfactory

of such

scintillants

as fission

fragments.

is dependent

feasibility

grown

studied

in this counting

retained

as

Ag I or

quantitatively

VI.

Pd12. for

the highly

energy

COLLECTION

parent

The of which

largest

collection

the author

er ences

given

The calling

attention

author

would

is aware

be included

to as many

in such

â&#x20AC;&#x201C; F.

Lawrence

Figure

nitrogen,

stainless condensates containing

F.

Momyer,

of train

balls

other

Kr

and plated samples

radiochemistry General

Ref-

with

a view

to The

as possible.

procedures

which

should

AND

Jr,

, et al.

of the

pump, -5

to 10

system

more,

used

of a trap

AIR

work

at

California

in the reparation.

refrigerated

A

in liquid

and a mechanical forepump is used to -6 mm Hg. Proceeding from Left to right

let us designate

glass

by a glass

unpublished

Liver

and label

1) a flowmeter;

of activated

Xe FROM

SEPARATION

Laboratory,

and suitable

and preceded 100 grams

10

OF

consisting

diffusion

the following: steel

gaa

description

concerning

a photograph

pressure

the separation

discussion

rare

and operations

SUBSEQUENT

arrangement

a mercury

a base

THEIR

Radiation

1 shows

pumping

separated

into the plated

one of the nine

for

techniques

1 â&#x20AC;&#x201C; REMOVAL

AND

standard

for were

a collection.

PROCEDURE

Source

plated Xe133

monograph. chosen

information

activities

PROCEDURES

with

in the last

were

useful

gas

GASES

dealing

of this

property

in vacuo.

RARE

is found

rare

was

growing

of heavy

(and not on ioniza-

activities, 135 and

RADIOCHEMICAL

THE

procedures

appreciate

even

of papers

at the beginning

following

Radioxenon

OF

that the rare 80, 81, 82 The

desirable

expended

of counting

of their

weeks,

FOR

along

have

instances

samples

in counters.

be borne in mind. For example Xe 83, 84 manner. Fission product iodine

out for

obtain

on total

to note

to be in the counting

They

only

solid

scintillants

promises

in specific

into

It ia interesting

should

counting,

was

found

usefulness

particles

scintillation

2) wool

coil;

charcoal;

34

Tl, plugs

3)

Cl, 4)

for a trap

purposes packed

to retain a trap

C z,

fine

similar

C3, and,c4,

of later with

3/16

particles

in. of

to Tl

but

three

small

-


Fig. 1 â&#x20AC;&#x201D;Separat;onsystena

used

35

in Procedures

1 and

1A.


PROCEDURE er traps trap

each

containing

similar

to the preceding

and

removal; through

the

8)

charcoal

trap

off from

the

photograph

trace

with

be directed behind

the drape), The

a vibrating

reed

of the bench.

during

thermocouple

respective

Grade-G yield

The

material.

system

is used

of samples, problem

tion

size,

has

work

The

yields

and partial

successfully

achieved

which

the largest is

100 cc STP about

the separation sample

into

of active

90%

for

is about

â&#x20AC;&#x153;pinnedâ&#x20AC;? 1.

the glass coil

feet

krypton

krypton 8 hours

the system.

and

Before on until

(probably

less

Gallon

dewars

coils.

The

the

the

than

the system,

of air

for

95~0

run all

are

of liquid

refrigerant

mm

Hg).

nitrogen

are

level

should

traps

vacuum

placed

types

not treat

a

of

which

separa-

a frame-

be described. into

a bottle

xenon.

time

required

have

gauge

con-

Average for

Bpent in bleeding

charcoal

thermocouple 10-4

The

to

various

for

of active

xenon.

and

and sieved

and to afford could

are

is Columbia

does

compressed

3 hours

traps tubing,

from

gases

seen

is the

the extremes

of rare

and 75 cc STP

of whibh

mill

gases

to represent

of operatiom

(STP)

large

char coal

in a ball

by

in the ionization

glass

admittedly

pressures with

The o. d.

to

partially

of the recorder

The

of rare below

chosen

number

100 cubic

to 350 â&#x20AC;&#x153;C and pumped is

It was

rates

sample

are

separation

chamber

and thence

of activity

of 22-mm

described

the

is amplified

the recorder

25 and 20 cm.

the

encountered. flow

been

within

taining

for

trap,

chamber

record

by this be closed

an ionization

charcoal

ground

may

that helium

and meter.

(6- 14 mesh),

obscured

nitro-

from

through

drives

traps

in liquid

not obvious

To the left

supply

about

and the procedure

often

sample

output

sample

so arranged

the ionization

a continuou6

power

charcoal

mesh

trap,

ia obtained.

are

been

for

to the line

cooled

Partially

subsequent

and the small

lengths

activated

20-50

Thus

gauge

of 41-mm

any

whose

a ~eparation

have

is

an unpacked

an outlet

and C ~ which

1 certainly

charcoal

through

electrometer

vacuum

constructed

into

current

at the right chamber

and stopcocks any

trap

T

It is

a stopcock.

through

This

between

7)

T2,

is admitted

the helium.

manometer

5)

a ZOO-CC bulb;

left.

from

charcoal;

Helium

lower

impurities

system

the atmosphere.

their

at the

is another

6)

manometer.

but connections

may

(unseen

trap

of activated

three;

a mercury

charcoal

gen to remove

flow

10 grams

1 (Continued)

been

the heated

in the manifold

on T ~ and C ~, including

be above

the

connection

from

to trap. 2.

ed to the librium

Through line

a pressure

below

pressure

gauge

the flowrneter,

o~er

C ~ is about

and reducing Sample 35 cm

36

Hg.

valve

is bled Wait

into

the sample

is cormect

T ~ and C ~ until

a few

minutes

until

equithe r -

-


PROCEDURE mal

equilibrium

boiling

is reached

of the liquid 3.

Using

establish

flow

35 cm

Hg pressure. air

Keeping until

with

10 cm Hg.

4.

all valves

from Close

to all

the charcoal

ization flow

nitrogen

is

from

Set up helium

rapid

), 6.

nitrogen, liquid

up,

slush

C2. stop 7.

* 61,

periods.

in at the above for

the pressure

rate

a few

in the bottle

removal

of the

efit at

minute

of T ~,

psi

gauge

in the traps

through

to the air.

from

C ~.

high

30 liters

Allow

pressures STP

water.

in about

5 minutes,

will

of air

Krypton

than

C ~,

the ion-

When

steady

C ~ to warm

in the

system

adsorbed

activity

will

the activity

S1OW1y (full -width

is lees

side 1-2

on C ~). be ob-

rising

rapidly

at half-maximum

1% of the peak

value

( 10-15

is halted. flow

of 750

Elute

per

flow

a couple

Corporatio~

and proceed cc/rein)

Equipment

.

37

through

to the air.

of minutes

approximately

(750

minute

and thence

in the ionization

immediately

the helium

cc STP

chamber,

appears

Research

Massachusetts

per

avoids

off more

at the helium

equilibrium

10-20°C

the activity

C2 and after

elution

Direct

National

is

the system.

nitrogen

(This

C ~ in

5â&#x20AC;&#x153;C).

If activity the

prolonged

quantitative

and thence

of the roughly

the ionization from

into

cc STP

nitrogen,

dropping

When

(-78.

1250

chamber

Set up helium

nitrogen

acetone

of

(4 cfm)

Pumping

and introduce

flow

the liquid

immerse

the elution

of

minutes.

and then

into

at about

condensation

Pump*

sample

reduce

and pres sure

of helium

in liquid

5-10

2 minutes).

minutes

will

sufficiently

Thermal

resorption

to a miximum

over

by C ~ and the stopcock

flow

in the ionization

about

of air

valving,

minute

to avoid

Ballast

the

suitable

S.TP per

one atmosphere.

C3 and C4,

remove

for

10 minutes

served

from

C2

established

too

After

C ~ and

Gas

bleed

completely

on C2,

by cessation

in air

amounts

represents

traps.

chamber,

slowly

open

This

from

is neceaaary

is about

the manometer

liquid

5.

and decreased

the bottle.

place

be evidenced

pressure

15 liters

Rotary

replenished,

in the bottle

to about

gases

pressure

large

nitrogen

minutes

on the exit

An NRC-4S

the necessary

the liquid

by steady

T ~ and C ~ of

Reduced

the pressure

rare

pump

through

in the system.

to handle

evidenced

nitrogen.

a mechanical

sample

liquid used

as

1 (Continued)

immerse

ten minutes chamber with

so that the

in liquid

C2

this

the

in dry

to remove

before

the next

Division,

C2

Remove

ice-

air

period

is

step.

sequence

Newton

is C2

Highlands

in


PROCEDURE dry

ice-acetone,

air.

Remove

The

krypton

and stop

the elution

Repeat

9.

With

Step

C4

less

no loss

than five

minutes,

10.

T2

residual

warming

nitrogen,

minutes

to conden~e

the

to the vacuum

krypton

in the

liquid

nitrogen

one pumps

tion

from

successively

pres

from

higher

ume

in the

5-10

of the system

and TZ may krypton

be

about

is

steady,

for

been Tz

the

907’.. and

cooled

in liquid

warmed