Nitrate Removal by Electrolysis Using Cu/BDD Electrode Cathode

Abstract

Copper particles were deposited in the potentiostact mode and under UV irradiation on the boron doped diamond (BDD) surface. The copper deposited presented high density and uniformity all over crystal faces. This behavior may be associated with its semiconductor character that promoted additional photogenerated electrons enhancing the copper reduction reaction. This modified electrode was used as a cathode electrode on the studies of the nitrates removal from aqueous solutions by electrolysis in an undivided electrochemical cell and BDD as an anode electrode. The nitrate reduction was analyzed at three differents initial pH (neutral, acid and basic). The nitrate reduction rate did not increase linearly as a function of current densities using potassium sulphate as the electrolyte (neutral pH). In the present experiment, the optimum current density was 20 mA/cm2. The nitrate reduction decreased from 150 to 63.8 ppm. Regarding to the influence of initial pHs used, it could be conclude that high value of pH favours the nitrate electroreduction. This result may be associated with the higher competition between the H+ and the NO3- ions by electrons on the cathode surface, causing a decrease in the efficiency of electrolysis.