Electrochemical removal of dimethyl phthalate with diamond anodes

BACKGROUNDIn this work, the electrolysis of dimethyl phthalate (DMP, a widely-use plasticizer) with conductive-diamond anodes is studied. RESULTSResults show that this technology is capable of depleting this pollutant in a wide range of initial concentrations. Although mass transfer limits the kinetics of the process, there is a significant contribution of mediated oxidation and the rate of the processes improve with increasing current density, while the efficiency decreases. A first stage in the oxidation of DMP consists of the attack on the methyl ester groups, and monomethyl phthalate and phthalate are the main aromatic intermediates. Further oxidation of these species results in the formation of maleic and oxalic acid, which behave as intermediates and are completely mineralized during the electrolysis. The presence of chloride in water leads to the formation of many more aromatic chlorinated intermediates from the action of hypochlorite on aromatics intermediates. Intermediates found and oxidation mechanisms proposed are consistent with those reported in the literature for other advanced oxidation processes. CONCLUSIONSDMP, TOC (total organic carbon) and COD (chemical oxygen demand) can be successfully removed using electrolysis with conductive-diamond anodes. DMP removal is faster than that of COD and TOC indicating the formation of reaction intermediates. (c) 2013 Society of Chemical Industry