Adriana Ramos Ruiz

Chemical and Environmental Engineering / College of Engineering

Microbial Recovery of Te0 Nanoparticles from Tellurate (TeO42-)

There is a great need for cost-effective and selective recycling methods to ensure a sustainable supply of scarce, critical elements needed for advanced technology. Biotechnology offers great promise to concentrate and refine these elements from waste streams.  This research focuses on the microbial recovery of tellurium (Te0) from aqueous streams containing soluble tellurium species.  Tellurium is a critical metalloid with a broad range of applications ranging from photovoltaic cells, medical applications, and additive to enhance optoelectronic and thermal properties of steel and glass.

The aim of this work was to investigate the recovery of Te0 nanoparticles from the soluble oxyanion tellurate (TeO42-) using an anaerobic mixed culture. Two electron donors, acetate and H2, were evaluated for their effectiveness in promoting the reduction of (TeO42-). The effect of four redox mediators (anthraquinone-2,6-disulfonate (AQDS), hydroxocobalamin, riboflavin and lawsone) was also tested. The results obtained in batch anaerobic bioassays revealed that Te reduction occurred only in the presence of microorganisms. The rate of Te reduction was enhanced in the presence of H2 and it was remarkably accelerated when lawsone was used as the redox mediator. The formation of Te0 nanoparticles was confirmed by electron microscopy analysis (TEM EDS). These encouraging results indicate that the use of redox mediators can accelerate microbial formation of Te0. Future research will consider the recovery of Te0 in a continuous-flow anaerobic bioreactor.