Electrochemical Activation of Nickel Oxide Catalyst for Wastewater Treatment

Abstract

Nickel oxide catalysts have been used for wastewater treatment due to their strong oxidizing power and air or chlorine has been utilized as a method of maintaining oxidation activity of the catalysts. However, such activation methods have low efficiency or problems such as generation of chloride ions. In this study, an electrochemical activation system was employed to the nickel oxide catalyst used for wastewater treatment. For the electrochemical use of the catalyst, a nickel oxide electrode was fabricated by calcination. The electrochemical activation system maintained oxidation activity of the nickel oxide while an organic compound was degraded in consecutive cycles. The nickel oxide catalyst with the electrochemical activation system showed comparable or better performance than nickel oxide powder or nickel oxide pellets with conventional air injection systems, in terms of maintaining oxidation activity. The oxidation mechanism of the electrochemical system was turned out to be the indirect oxidation mechanism of high oxidation states of nickel oxide, which were electrochemically regenerable. For its practical use, the electrochemical system was applied to actual phenolic wastewater and 98 % of COD was eliminated.