Redox-Mediated Electrosorption for Chemical and Environmental Separations

X. Su, X. Mao, Y. Ren, K-J Tan, T.A. Hatton
United States

Keywords: redox polymer, micro pollutants, electrochemical cell, water treatment


A significant fraction of the world’s population is faced with an inadequate supply of clean or potable water owing to geographical scarcity and/or environmental pollution from anthropogenic sources. A major problem of emerging concern is the prevalence of micropollutants (e.g., organic endocrine disruptors, pesticides, household chemicals, dyes) in natural water resources for which current purification technologies are inadequate owing to high energetic penalties and performance limitations when confronted with these contaminants at very low concentrations (nM to μM), often in the presence of excess competing species. Other pollutants are the heavy metals and metalloids used in industrial and technological applications (e.g., chromium, lead, cadmium, nickel, mercury, arsenic and copper) and are distributed widely in natural water bodies and soil. To ensure an adequate supply of water to affected communities, it is clear that new affordable and robust water treatment technologies need to be developed and implemented over a range of different scales from local, point-of-source purification in remote rural settings, to large scale, centralized wastewater treatment facilities. We report on a platform purification technology based on redox-mediated electrochemical modulation of the separation environment, which can, in many cases, offer significant advantages over conventional separation methods. Redox-mediated chemical moieties tethered to electrode surfaces can be tailored to ensure adsorptive selectivity with high separation factors towards toxic pollutants ranging from pesticides to toxic heavy metals, at low overpotentials and high current efficiencies. Capture and release are controlled solely by the electrochemical potential, and thus there is no need for chemical regenerants or post-treatment, with little chemical waste produced and low water usage ratios. Due to their electrochemical nature, redox-based systems can be integrated readily with renewable energy sources in remote locations (e.g. agricultural waterscape or villages in the developing world). In the long-term, such energy-efficient selective electrochemical methods offer a potentially powerful solution for water purification and resource recovery across a range of scales. This presentation will provide an overview of the general principles of these energy-efficient selective electrochemical methods, which offer a powerful solution for water purification and resource recovery needs across a range of scales, and an assessment of their energy demands and economic of implementation.