Steter, Juliana R.Brillas, EnricSirés Sadornil, Ignacio2020-03-162017-10-270926-3373https://hdl.handle.net/2445/152797Aqueous mixtures of methyl, ethyl and propyl paraben (MeP, EtP and PrP) prepared in real urban wastewater with low conductivity were treated by solar photoelectro-Fenton (SPEF) process at low input current (j = 10 mA cm-2) using a pre-pilot plant with an electrochemical reactor equipped with an air-diffusion cathode to electrogenerate H2O2 and a boron-doped diamond (BDD) or RuO2-based anode. Comparative trials in simulated water matrices with or without Cl− in the absence of natural organic matter (NOM) always led to a slower decay of parabens concentration and total organic carbon (TOC). This was mainly due to the superior regeneration of Fe2+ from photoreduction of Fe(III) complexes formed with NOM in real wastewater compared to that from Fe(OH)2+. In all matrices, a catalyst concentration as low as 0.20 mM Fe2+ was enough to ensure the production of ¿OH in the bulk from Fenton's reaction. SPEF with BDD yielded a complete removal of parabens in 180 min and 66% mineralization at 240 min. This gave rise to the greatest mineralization current efficiencies reported so far, up to 1000%, with a low energy consumption of 84 kWh (kg TOC)-1. The synergy between homogeneous and heterogeneous catalysis, which allowed the efficient dosage of ¿OH and M(¿OH) at low j, with simultaneous action of high UV power from sunlight justified such a good performance. Analogous apparent rate constants were determined for MeP, EtP and PrP. Slower decays were found with RuO2-based anode due to its lower oxidation power. As a result, the MCE was 425% as maximum, but a lower energy consumption of 52 kWh (kg TOC)-1 was needed. Since the role of active chlorine was of minor importance, the formation of toxic, refractory chloroderivatives was minimized. All by-products were transformed into malic, formic and oxalic acids prior to total mineralization.9 p.application/pdfengcc-by-nc-nd (c) Elsevier B.V., 2018http://creativecommons.org/licenses/by-nc-nd/3.0/esElectroquímicaDepuració de l'aiguaElectrochemistryWater purificationinfo:eu-repo/semantics/article6741402020-03-16info:eu-repo/semantics/openAccess