Guelfi, Diego Roberta de VieiraYe, ZhihongGozzi, FábioDe Oliveira, Silvio CésarMachulek Jr., AmílcarBrillas, EnricSirés Sadornil, Ignacio2020-01-132020-10-162018-10-161383-5866https://hdl.handle.net/2445/147683This article reports the electrochemical degradation of the herbicide metribuzin (MTZ) in sulfate medium by advanced oxidation processes like anodic oxidation with electrogenerated H2O2 (AO-H2O2), electro-Fenton (EF) and UVA photoelectro-Fenton (PEF). A boron-doped diamond (BDD) anode was combined with an air-diffusion cathode with ability to produce H2O2. Unprecedented overall combustion was feasible by all methods at a constant current density (j) ≥100.0 mA cm−2. The total organic carbon (TOC) removal achieved by AO-H2O2 was independent from pH within the range 3.0-9.0, whereas the oscillatory dependence of the pseudo-first-order MTZ decay rate constant with this variable was ascribed to adsorption on the BDD surface. In EF and PEF at pH 3.0, 0.50 mM Fe2+ was determined as optimum catalyst content and the MTZ removal showed two consecutive pseudo-first-order kinetic stages. These were related to the fast reaction of the target molecule with OH formed from Fenton's reaction, followed by a slower attack of physisorbed BDD(OH) onto Fe(III)-MTZ complexes. The effect of j and MTZ content on decay kinetics and TOC removal was examined. PEF was the best treatment due to the decomposition of photoactive intermediates by UVA radiation, yielding total mineralization of a 0.523 mM herbicide solution after 420 min of electrolysis at 100.0 mA cm−2. A thorough reaction pathway for MTZ degradation is proposed from the sixteen heteroaromatic by-products and three aliphatic molecules identified by GC-MS and LC-MS/MS. Oxalic and oxamic acids were detected as final carboxylic acids by ion-exclusion HPLC.9 p.application/pdfengcc-by-nc-nd (c) Elsevier B.V., 2018http://creativecommons.org/licenses/by-nc-nd/3.0/esOxidació electroquímicaDepuració d'aigües residualsHerbicidesElectrolytic oxidationPurification of sewageHerbicidesinfo:eu-repo/semantics/article6826632020-01-13info:eu-repo/semantics/openAccess