Application of boron-doped diamond (BDD) anodes to electrochemical oxidation of organic pollutants

Abstract

1,4-dioxane has been widely used as a solvent and as a stabilizer for chlorinated solvents, particularly 1,1,1-trichloroethane. Conventional water and wastewater treatment processes are generally ineffective in removing 1,4-dioxane because of its high aqueous solubility and resistance to biodegradation. Recently, advanced oxidation processes (AOPs), which use the hydroxyl radical as the oxidant, can achieve the high removal efficiency of aqueous organic pollutants. Especially electrochemical advanced oxidation processes (EAOPs) can show good efficiency with many advantages. In this process, the key part is anode materials. Among these materials, boron-doped diamond (BDD) films are widely being studied due to chemical inertness and unique electrochemical properties. Therefore in this study, the removal behavior of 1,4-dioxane by BDD electrodes was investigated with several major system variables-initial concentration, current density, temperature, pH and electrolyte concentration. In addition the deposition of BDD films were performed by HFCVD methods. Low initial concentration, low current density and, high temperature conditions were more beneficial for saving energy consumption. Higher current density showed the faster degradation rate of 1,4-dioxane, but needed the higher charge loading into the system. Therefore, the compromise between time and energy consumption should be required. There were no effects of pH and electrolyte concentration. Therefore, the wide effective pH range implies that pH adjustment before wastewater treatment is not necessary in most cases. Besides the removal efficiency of COD was shown as more than 95 % in most experimental conditions, and there were acceptable agreements between experimental and theoretical data. The BDD films were successfully deposited on the p-type Si-substrates using the HFCVD methods under the specific conditions.