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SUMMARY Achieving the greatest cleanup efficiency with minimal footprint remains a paramount goal of the water treatment industry. Toxic organic compounds threaten drinking water safety and require effective pretreatment. Hydroxyl radicals produced by the Fenton process (Fe 2+ /H 2 O 2 ) destroy organic contaminants based on their strong oxidation potential. An upgraded reaction using solid catalysts, referred to as the Fenton-like process, was recently adopted to avoid the ferric sludge generation during the conventional Fenton process. However, most heterogeneous Fenton-like catalysts operate optimally at pH 3–5 and quite weakly in near-neutral water bodies. Here, we evaluate the feasibility of an electrolytically localized acid compartment (referred to as the Ella process) produced by electrochemical water splitting under flow-through conditions to facilitate the Fenton-like process. The Ella process boosts the activity of an immobilized iron oxychloride catalyst >10-fold, decomposing organic pollutants at a high flow rate. The robust performance in complex water bodies further highlights the promise of this platform.

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The electrochemical degradation of ibuprofen (IBP) by electro-Fenton process has been studied in a flow-through system by evaluating the performance of two different iron sources, sacrificial cast iron anode and FeSO4 salt. The effect of operating conditions, including initial IBP concentration, cast iron anode location, initial FeSO4 concentration, applied current, the split current on the iron anode, solution pH, and flow rate on the efficacy of the process was evaluated. The sequence of the electrodes significantly influences ibuprofen removal. When using cast iron anode as iron source, placing the iron anode upstream achieved the best IBP removal rate. Split current of 3 mA applied on the iron anode out of 120 mA total current is the optimum current for remove 1 mg/L of IBP under a flow rate of 3 mL/min. There is a linear correlation between the applied current and the Fe2+ concentration in the FeSO4-system. The initial IBP concentration does not influence the rate of Fenton reaction. Flow rate influences the degradation efficiency as high flow rate dilutes the concentration of OH radicals in the electrolyte. FeSO4-system was less affected by the flow rate compared to the iron anode-system as the concentration of the Fe2+ was steady and not diluted by the flow rate. Both systems prefer acidic operation conditions than neutral and alkaline conditions. Iron-anode can be used as an external Fe2+ supply for the treatment for iron-free. These findings contribute in several ways to our understanding of the electro-Fenton process under flow conditions and provide a basis for how to design the reactor for the water treatment.

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