• Filtration maximizes •OH production by activating the full electrode area. • Flow-through behavior shifts the oxygen evolution potential anodically. • Flow-through mode is the optimal operation condition for EF. • Flow-by mode loses over 70% of the active area at high flow rates. Electrofiltration is an emerging electrochemical technique that enables simultaneous filtration and advanced oxidation for water treatment, offering improved control over mass transport and surface activation compared with conventional electrochemical process. Ceramic 3D Sb-doped SnO 2 porous electrodes have been proven to be suitable electrofiltration anodes. In this work, the impact of hydrodynamics on the electrochemical behavior and oxidizing capability of such electrofiltration anodes was investigated. Cyclic voltammetry revealed that, without filtration, the system behaves as a quasi-2D flow-by electrode with low internal resistance, limited electroactive area and low oxygen evolution potential at high injection flow. Under filtration, the system behaves as a 3D flow-through electrode exhibits a higher ohmic resistance for all the tested flow rates, an anodic shift of the oxygen evolution potential and a higher activated area. The ability to generate hydroxyl radicals was assessed by salicylic acid electrofiltration and quantification of 2,5- dihydroxybenzoic acid and 2,3-dihydroxybenzoic acid, confirming that hydroxyl radical production at 20 L/h is effective both, without filtration and with filtration; whereas at 60 L/h it is strongly hindered in flow-by mode and only partially recovered under flow-through operation. These findings highlight the critical role of hydrodynamics in electrofiltration with porous ceramic Sb–SnO₂ anodes and provide a mechanistic link between flow regime, electrochemical response and radical-mediated oxidation performance.
Carvalho-Rosa et al. (Sun,) studied this question.