2026-04-17T08:16:21Zhttps://recercat.cat/oai/request

oai:recercat.cat:2445/1673182025-12-04T20:53:59Zcom_2072_1057col_2072_478796col_2072_478917

00925njm 22002777a 4500 dc Márquez, Ana A. author Sirés Sadornil, Ignacio author Brillas, Enric author Nava, José L. author 2020-07-02T09:17:29Z 2022-06-23T05:10:21Z 2020-06-23 2020-07-02T09:17:29Z This work addresses the mineralization of the widely used Methyl Orange (MO) azo dye by technologies based on H2O2 electrogeneration at a 3D-like air-diffusion cathode. These include two Fe2+-catalyzed processes such as electro-Fenton (EF) and photoelectro-Fenton (PEF). Bulk electrolyses were performed in a recirculation flow plant, in which the Eco-Cell filter-press electrochemical reactor was connected in series with a UVA photoreactor. The former reactor was equipped with a Ti|Ir-Sn-Sb oxide plate anode alongside a 3D-like air-diffusion cathode made from graphite felt and hydrophobized carbon cloth, aimed at electrogenerating H2O2 on site. The influence of current density (j), volumetric flow rate (Q) and initial MO concentration was examined. The greatest oxidation power corresponded to PEF process. The best operation conditions to treat 30 mg L-1 of total organic carbon of MO in a 50 mM Na2SO4 solution by PEF were found at 0.50 mM Fe2+, pH 3.0, j = 20 mA cm-2 and Q = 2.0 L min-1, obtaining 100% and 94% of color and TOC removals at 240-300 min, respectively. This accounted for 35% of mineralization current efficiency and 0.12 kWh (g TOC)-1 of energy consumption at the end of the electrolysis. The oxidation power of EF and PEF was compared with that of anodic oxidation (AO), and the sequence obtained was: PEF > EF > AO. The dye was gradually degraded, yielding non-toxic short carboxylic acids, like maleic, fumaric, formic, oxalic and oxamic, whose Fe(III) complexes were rapidly photolyzed. Depuració d'aigües residuals Oxidació electroquímica Purification of sewage Electrolytic oxidation Mineralization of Methyl Orange azo dye by processes based on H2O2 electrogeneration at a 3D-like air-diffusion cathode