Veratric acid treatment by anodic oxidation with BDD anode

BACKGROUND: Veratric acid (VA, 3,4-dimethoxy-benzoic acid) is one of the most representative polyphenolic type compounds present in OMW. Given the bactericide factor, the inhibitor character and the anti bacteriological activity of this compound, the traditional biological digestion cannot be applied and therefore new technologies, such as electrochemical oxidation using the promising boron-doped diamond (BDD) anode have to be taken into consideration to ovoid its accumulation in the environment. RESULTS: The electrochemical oxidation of aqueous solutions containing 1 mM VA has been investigated using a filter-press reactor with a boron-doped diamond (BDD) anode under galvanostatic electrolysis. The influence of several operating parameters, such as applied current density, temperature, flow-rate and supporting electrolyte concentration and type has been investigated. The experimental results showed that in our experimental conditions the oxidation of veratric acid was under mass-transfer control and veratric acid was completely degraded by the reaction with hydroxyl radicals electrogenerated at the BDD surface. The COD decay kinetic follows a pseudo first-order reaction and the apparent rate constant increased with flow rate and temperature. Under optimal experimental conditions of flow-rates (i.e. 300 L h-1), temperature (T=35 \ub0C) and current density (i.e. 10 mA cm-2), 99.5 % of COD was removed in 2h electrolysis, with 16.4 kWh m-3 energy consumption. CONCLUSIONS: This study suggest that anodic oxidation with BDD electrode constitutes an excellent method for the treatment of effluents contaminated with VA and related polyphenols