Street Broad Scientific Desorption Experiment for Reuse Adsorbent pieces contained in samples from the comparison of unmodiied and modiied cellulose were dried on iberglass screen. If the pieces were to be added back into the ground as fertilizer, the characteristic of nitrate leaching out would be important. In order to examine possible signiicance in reusability, the adsorbents were placed in separate beakers of 6 mL of water. After three days of soaking, the nitrate as nitrogen concentration of the water was measured as a representation of desorption, to be compared to the original amounts adsorbed by the particles and considered for efectiveness of nitrate reuse.
REsEaRch adsorbed per gram adsorbent.
Results and Discussion Efect of Centrifuge Methods he data collected directly from the nitrate probe produce plots of concentration versus time (Fig. 3), which cannot be easily directly used. For the study of the efect of centrifuge methods, as in subsequent studies, several steps were taken to obtain a more useful form. he mean concentration was calculated for each sample, but only considering the latter 75% of the data for each sample. hat is, the values measured from the irst 25% of total time for each sample were disregarded to allow the nitrate ISE to reach stability. In particular, measurements related to the previously mentioned CB1, CB2, and CB3 methods were analyzed. Once singular data points associated with each sample contained within each set of data were determined, they were then used in their respective analyses.
Figure 4. Average concentrations of solutions using different centrifuge methods.
Table 1. Comparison data for centrifuge methods. he data indicates CB3 as the most efective procedure because centrifuging samples multiple times may improve adsorption, as the adsorbent and the nitrate that has already been collected on it are physically separated from the solution to decrease homogeneous desorption while still allowing for extended contact time. CB3 was used for all subsequent batch studies. hough of these methods CB3 produced the greatest adsorptive result, a ratio of approximately 1 milligram adsorbed per gram of adsorbent leaves much room for improvement.
Figure 3. Format of raw data when measuring concentrations (mg/L NO3) for centrifuge methods CB1, CB2, and CB3 using ISE. Comparison he average concentrations for samples run with no CB, CB1, CB2, and CB3 are shown in Fig. 4. To appropriately compare the methods, the concentrations were converted to mass of nitrate as nitrogen to then evaluate milligrams 36 | 2012-2013 | Volume 2
Figure 5. Average concentrations of solutions with unmodiied and modiied CB. Error bar indicates standard deviation of concentrations with chitosanmodiied CB.