A photoelectrochemical system demonstrated by University of Illinois Urbana-Champaign researchers offers a renewable energy-based route to efficient water purification and remediation.

The photoelectrochemical redox-mediated ion separation system effectively manipulates the ionic charge of impurities to facilitate their separation from aqueous solutions. To realize proof-of-concept light-driven redox reactions for ion capture using solar energy, vertically standing titanium dioxide nanorods were grown on fluorine-doped tin oxide glass substrates. Polyvinyl ferrocene-functionalized carbon nanotubes were then coated on the nanorod arrays and tested for redox-mediated electrosorption of molybdenum, arsenic, and chromium compounds selected for their relevance as major waste components from the semiconductor, steel, mining and chemical industries.

The photovoltaics-enabled system was observed to induce spontaneous redox-reactions that enabled heavy metal oxyanion capture with zero electrical energy under solar irradiation. The voltage of the photoelectrochemical cells under no bias light condition is negative, indicating that the separation reaction is spontaneous and that the cell generates electrical energy by converting solar energy.

As reported in the journal Small, the process also achieved an uptake capacity comparable with that of a traditional electrochemical separation system while reducing electrical energy consumption by 51.4%. Dilute arsenate was efficiently removed from real wastewater samples, confirming the feasibility of photoelectrochemical redox-separation technology systems for wastewater treatment and environmental remediation.

To contact the author of this article, email shimmelstein@globalspec.com