Destruction of refractory humic acid by electromechanical oxidation process

Electrochemical oxidation of humic acid has been conducted to evaluate the efficacy of the process for the destruction of high-molecular-weight (HMW) compounds. Experimental results show that the destruction of humic acid obtained by the electrolysis supported by chloride ion is much better than that obtained by sulfate ion. Accordingly, HMW compound such as humic substance is suggested to be resistant to directly anodic oxidation, but to be readily destroyed by an indirect oxidation of chlorine/hypochlorite during an electrochemical treatment process. The effects of operating parameters, including anode material, current density, electrolyte concentration, have been investigated in this study. A tertiary-oxide of Sn, Pd, Ru coated titanium (SPR) anode with high electrocatalytic activity was found to have high efficiency for humic acid destruction, and the destruction efficacy of humic substance increased with increasing current density and chloride concentration. In this study, gel permeation chromatography (GPC) and adsorptive organic halide (AOX) had been performed to examine the variation of organic characteristics during the electrochemical oxidation of humic acid. The results from GPC and AOX show that HMW organic compounds could be effectively destroyed by electrochemical oxidation process, and the process also produced less undesirable chlorinated byproducts than the chlorination process. From the above results, the electrochemical oxidation conducted by indirect oxidation effect of chlorine/hypochlorite could be concluded to be a feasible method for the destruction of HMW compounds.