Electrochemical selenium removal and extraction

Selenium contamination in water arises from activities such as power generation, mining, and agriculture, where it is released as soluble oxyanions (Se(IV) and Se(VI)) that are mobile, bioaccumulative, and tightly regulated due to ecosystem and human health risks . Our research develops electrochemical pathways to selectively convert these species into elemental selenium, Se(0), a stable and separable form for removal and potential recovery. We first established the fundamental mechanisms of direct electrochemical reduction (SeDER), identifying four- and six-electron pathways and showing how kinetics, phase transformation, and electrode passivation govern performance. We then demonstrated the impact of real water chemistry, where competing ions (e.g., nitrate, sulfate, chloride) influence efficiency through cathodic competition and anodic side reactions. To improve practicality, we identified cost-effective cathode materials such as graphite that achieve high removal efficiency without relying on precious metals, and extended the approach to kinetically limited Se(VI) using TiO₂-assisted electrocatalysis, achieving >80% removal with low energy input. Most recently, we translated these advances into a three-dimensional packed-bed electrochemical reactor that enhances surface area, mass transfer, and scalability, enabling sustained treatment of both synthetic and real wastewaters. Together, this work advances electrochemical selenium treatment from mechanism to materials to reactor design, with ongoing efforts focused on energy efficiency, stability in complex waters, and field-scale deployment.