The electro-Fenton process is based on in-situ production of the Fenton's reagent in order to continuously generate hydroxyl radicals in the bulk solution. It is also possible to promote the generation of additional powerful oxidant species by using anode material with high oxygen evolution overpotential. Therefore, such electrochemical advanced oxidation process (EAOP) is able to degrade a large range of organic pollutants. However, energy efficiency of EAOPs is strongly affected by mass transport limitations during the treatment of low concentrations of pollutants such as pharmaceutical residues. In fact, a large amount of hydroxyl radicals are wasted in parasitic reactions such as hydroxyl radical dimerization. The combination of adsorption and electro-Fenton processes aims at overcoming this drawback. Adsorption on activated carbon fibers (ACFs) is used for pre-concentration of organic pollutants. Then, ACFs can be directly used as cathode during the electro-Fenton process for desorption, degradation and mineralization of organic compounds as well as for regeneration of ACFs for additional adsorption steps. The possibility to easily regenerate ACFs improve the cost-effectiveness of this material, which presents more suitable characterisitcs than grain or powder activated carbon (e.g. low intra-particle diffusion limitation leading to fast adsorption kinetics, narrow pore size distribution leading to selective adsorption of micropollutants). This innovative strategy was applied for the removal of pharmaceutical residues. Scale-up from batch to continuous filtration reactor was investigated.
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