Cold incineration of 1,2-dichlorobenzene in aqueous solution by electrochemical advanced oxidation using DSA/Carbon felt, Pt/Carbon felt and BDD/Carbon felt cells

Abstract

This study reports on the electrochemical degradation and mineralization of 1,2-dichlorobenzene, called also ortho-dichlorobenzene (o-DCB) in aqueous solution, using an undivided electrochemical reactor for the application of electro-Fenton (EF) process. The o-DCB was chosen as model pollutant because of its high toxicity and persistence in the environment. Among the different parameters influencing process efficiency, the effect of different anode materials such as DSA, BDD and Pt on the production of hydroxyl radicals ((OH)-O-center dot) was investigated. These radicals were generated concomitantly from the oxidation of water on the anode surface and from electrochemically generated Fenton's reagent in bulk of solution. The effects of current, supporting electrolyte and the nature of the anode material on degradation kinetic and mineralization efficiency were studied. The absolute rate constant for oxidation of o-DCB by (OH)-O-center dot was determined as (1.61 +/- 0.02) x 10(9) M-1 s(-1) by using the competition kinetic method. Mineralization of o-DCB aqueous solution was monitored using total organic carbon (TOC) analysis. Under optimum conditions, i.e., 500 mA current, BDD anode and CF cathode, treatment of o-DCB solution containing 50 mM Na2SO4 and 0.1 mM Fe2+ at pH = 3.0 conducted to more than 90% TOC removal in 3 h electrolysis. Oxidative degradation products formed during the treatment (aromatic intermediates and short-chain carboxylic acids) or end-products (inorganic ions) were identified and quantified by using HPLC and ion chromatography techniques respectively, and based on the identified products a degradation pathway for mineralization of o-DCB was proposed.