Electrochemical treatment of 2,4-dinitrophenol aqueous wastes using boron-doped diamond anodes

The electrochemical oxidation of 2,4-dinitrophenol (2,4-DNP) aqueous wastes has been studied using both, bulk electrolysis and voltammetric techniques. To carry out the bulk electrolysis, a bench-scale plant with a single compartment electrochemical flow cell was used. Boron-doped diamond (BDD) materials were used as the anode and stainless steel (AISI 304) as the cathode. According to the obtained results, a simple mechanistic model has been proposed. The oxidation of 2,4-DNP leads to the appearance of phenol and quinonic compounds and to the release of the nitro groups from the aromatic ring, in a first step. In a second step, these organics are transformed into carboxylic acids (mainly maleic and oxalic acid). The process ends with the formation of carbon dioxide (CO2). The effects of the waste characteristics (composition and pH) and of the operation parameters of the process (temperature and current density) have also been studied in this work. The complete removal of the organic compounds contained in the waste has been obtained in all essays. (C) 2004 Elsevier Ltd. All rights reserved.