Electrochemical degradation of humic acid

The treatment of natural water for drinking water production goes through the degradation of humic substances. In this study, humic acid, extracted from a peat area located at the margins of the Mogi Guaçu River at São Paulo State, Brazil, was used to perform electro-oxidation essays in order to evaluate the possibilities of electrochemical methods in the degradation of humic substances. The working electrodes were dimensionally stable anodes (DSA) type with the following compositions: Ti/Ir 0.3Ti 0.7O 2; Ti/Ru 0.3Ti 0.7O 2; and Ti/Ir 0.2Ru 0.2Ti 0.6O 2. The electrolyses were performed by using a solution composed of an electrolyte support (0.1 mol l −1 KCl) and 30 mg l −1 of the humic acid. Samples were taken during the electrolyses and analysed by the pH, transmittance, UV-vis spectra and chromatography. The results show that the Ti/Ru 0.3Ti 0.7O 2 electrode presents the best performance considering the elimination of most of the electro-oxidation products after approximately 2 h of electrolysis at 40 mA cm −2.