The electrochemical oxidation of organics in water was investigated theoretically andexperimentally to determine the role of several operative parameters on the performancesof the process in the presence and in the absence of sodium chloride. Theoreticalconsiderations were used to design the experimental investigation and were confirmed bythe results of the electrochemical oxidation of oxalic acid (OA) at boron doped diamond(BDD) or IrO2–Ta2O5 (DSA-O2) anodes in a continuous batch recirculation reaction systemequipped with a parallel plate undivided electrochemical cell. Polarization curves andchronoamperometric measurements indicated that, in the presence of chlorides, theanodic oxidation of OA is partially replaced by an indirect oxidation process. This resultwas confirmed by electrolyses experiments that show that, in the presence of suitableamount of chlorides, oxidation of OA takes place mainly by a homogeneous process.Interestingly, a very different influence of the nature of the anodic material, the flow rateand the current density on the performances of the process arises in the absence and in thepresence of chlorides so that optimization of the two processes requires very differentoperative conditions. In the absence of chlorides, high current efficiency (CE) is obtained atBDD when most part of the process is under charge transfer controlled kinetics, i.e. whenlow current densities and high flow rates are imposed. On the other hand, in the presenceof NaCl, higher CE are generally obtained at DSA anode when high current densities andlow flow rates are imposed, i.e. when a high concentration of chemical oxidants is obtainedas a result of the chloride oxidation. The effect of other operative parameters such as theOA concentration and the pH were further investigated.
|Numero di pagine||13|
|Stato di pubblicazione||Published - 2009|
All Science Journal Classification (ASJC) codes