RESEARCH
Bacteriophages extract raw materials from fluorescent lamps Rare earths are important materials in complex electronics. Seventeen different metals such as lanthanum, cerium, europium and terbium that are essential components of smartphones, flat screens, wind turbines and compact fluorescent lamps. China is the world market leader for the supply of rare earths, covering 86 percent of global demand and even 98 percent of Europe's demand. To reduce this dependence and protect the environment, innovative recycling technologies are needed. Researchers at the Helmholtz Institute Freiberg for Resource Technology (HIF) of the Helmholtz Center Dresden-Rossendorf (HZDR) have developed a process that allows them to extract rare earth metals from fluorescent lamps. The trick: bacteriophages: viruses that primarily infect bacteria. Waste electronic products contain a variety of valuable elements in very low concentrations. These include compact fluorescent lamps, which are currently
Using phage technology, the appropriate element-specific biomolecule is selected from bacteriophages containing one billion different biomolecules. This biomolecule is then produced biotechnologically and anchored on a spherical magnetic carrier material. This creates biocollectors that can recognize and bind their target element in a targeted manner (Image: Dr Franziska Lederer)
The vial contains magnetite particles functionalized with rare earth binding biomolecules. The magnet on the right attracts the particles (Image: HZDR/Detlev Müller)
6 | INNOVATIVE MATERIALS 5 2022
collected separately from other electronic waste because the mercury-containing powder from the lamp has to be stored in special storage facilities. This powder contains barium magnesium aluminate, cerium magnesium aluminate, lanthanum phosphide, halophosphate and yttrium phosphide. By 2020, 25,000 tons of fluorescent powder had accumulated in the EU, of which 750 tons were rare earth metals. A share of 4,200 tons is assumed for other electronic end-oflife products. Therefore, HIF researchers have taken the lamp powder as a basis to demonstrate that it is possible and economically feasible to recover the elements contained in it. For recovery, they use a magnetic separation technique based on biocollectors: so-called 'Phage Surface Displays' (PSD).
