Person:

Bonificio, William Daley

Aims: Tellurium-based devices, such as photovoltaic (PV) modules and thermoelectric generators, are expected to play an increasing role in renewable energy technologies. Tellurium, however, is one of the scarcest elements in the earth's crust, and current production and recycling methods are inefficient and use toxic chemicals. This study demonstrates an alternative, bacterially mediated tellurium recovery process. Methods and Results: We show that the hydrothermal vent microbe Pseudoalteromonas sp. strain EPR3 can convert tellurium from a wide variety of compounds, industrial sources and devices into metallic tellurium and a gaseous tellurium species. These compounds include metallic tellurium (Te0), tellurite (TeO32−), copper autoclave slime, tellurium dioxide (TeO2), tellurium-based PV material (cadmium telluride, CdTe) and tellurium-based thermoelectric material (bismuth telluride, Bi2Te3). Experimentally, this was achieved by incubating these tellurium sources with the EPR3 in both solid and liquid media. Conclusions: Despite the fact that many of these tellurium compounds are considered insoluble in aqueous solution, they can nonetheless be transformed by EPR3, suggesting the existence of a steady state soluble tellurium concentration during tellurium transformation. Significance and Impact of the Study These experiments provide insights into the processes of tellurium precipitation and volatilization by bacteria, and their implications on tellurium production and recycling.

The rare-earth elements are critical to many green energy technologies but are difficult to separate from one another because of their chemical similarity. We demonstrate an alternative, biogenic method based on the adsorption of lanthanide to the bacterium Roseobacter sp. AzwK-3b, immobilized on an assay filter, followed by subsequent desorption as a function of pH. The elution desorption data suggest that the basicity of the individual lanthanides is important in determining their desorption behavior. It is found that via preprotonation of the bacteria it is possible to concentrate a solution of equal concentrations of each lanthanide to nearly 50% of the three heaviest lanthanides (Tm, Lu, and Yb) in just two passes. This surpasses existing industrial practice. The findings suggest that there is an opportunity to harness the diversity of bacterial surface chemistry to separate and recover technologically important rare-earth metals in an environmentally benign manner.