Natural Iron as a Decentralized Catalyst Supply for Electrochemical Groundwater Treatment

Decentralized technologies, such as advanced oxidation processes (AOPs), offer an opportunity to destroy organic groundwater pollutants at their point-of-use but often require the addition of expensive catalyst materials and chemical reagents. Overlooked as a common nuisance in groundwater systems, natural iron has the potential to be used as an autochthonous catalyst in the abatement of organic contaminants via Fenton oxidation, a well-known AOP. However, its usefulness is hindered by the circumneutral pH of groundwater, which leads to its precipitation upon reacting once with ROS-generating oxidants such as hydrogen peroxide. As a solution to this issue, we developed a novel electrochemical flow-through system which enhances oxidation of organic pollutants via anodic redissolution of Fe³⁺ and cathodic regeneration of Fe²⁺. The electrochemically enhanced Fenton system displays excellent capacity for treating high concentrations of various pollutants in a single pass, using high, but environmentally relevant, levels of ferrous iron as the sole source of catalyst. Moreover, the modular, decentralized cell design and use of cheap graphite felt electrodes enables practical and energy efficient degradation of contaminants, well-suited for point-of-use applications. If paired with electrochemical hydrogen peroxide generation from oxygen in air, this technology presents an opportunity for "reagent-free" treatment of iron-rich, contaminated groundwater.