Veratric acid treatment by anodic oxidation with BDD anode

Abstract

BACKGROUND: Veratric acid (VA, 3,4-dimethoxy-benzoic acid) is representative of the polyphenolic type compounds present in olive mill wastewater (OMW). Given the bactericide factor, the inhibitor character and the anti bacteriological activity of this compound, traditional biological digestion cannot be applied and therefore new technologies, such as electrochemical oxidation using a boron-doped diamond (BDD) anode have to be considered to avoid its accumulation in the environment. RESULTS: The electrochemical oxidation of aqueous solutions containing 1 mmol L−1 VA has been investigated using a filter-press reactor with a BDD anode during 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 under the experimental conditions used the oxidation of VA was under mass-transfer control and VA was completely degraded by the reaction with hydroxyl radicals electrogenerated at the BDD surface. The chemical oxygen demand (COD) decay kinetic followed a pseudo-first-order reaction and the apparent rate constant increased with flow rate and temperature. Under optimal experimental conditions of flow-rate (300 L h−1), temperature (35 °C) and current density (10 mA cm−2), 99.5% of COD was removed during 2 h electrolysis, with 16.4 kWh m−3 energy consumption. CONCLUSIONS: This study suggests that anodic oxidation with a BDD electrode is an excellent method for the treatment of effluents contaminated with VA and related polyphenols. Copyright © 2011 Society of Chemical Industry