Mineralization of p-methylphenol in aqueous medium by anodic oxidation with a boron-doped diamond electrode

The electrochemical oxidation of pesticide, p-methylphenol (PMP) as one kind of pesticide that is potentially dangerous and biorefractory, was studied by galvanostatic electrolysis using boron-doped diamond (BDD) as anode. The influence of several operating parameters, such as applied current density, supporting electrolyte, and initial pH value, was investigated. The best degradation occurred in the presence of Na2SO4 (0.05 M) as conductive electrolyte. After 8 h, nearly complete degradation of p-methylphenol was achieved (95%) using BDD electrodes at pH = 3 and at current density equals 60 mA cm(-2). The decay kinetics of p-methylphenol follows a pseudo-first-order reaction. Aromatic intermediates such as 3-methylcatechol, methyihydroquinone and methylbenzoquinone and carboxylic acids such as maleic, formic, fumaric, acetic, succinic, glyoxylic and oxalic, have been identified and followed during the PMP treatment by chromatographic techniques. From these anodic oxidation by-products, a plausible reaction sequence for PMP mineralization on BDD anodes is proposed. (C) 2016 Elsevier B.V. All rights reserved.