Evaluation of anode materials for the electro-oxidation of ammonia and ammonium ions

The electrochemical treatment of effluents has been used as an alternative to conventional treatments because of advantages such as environmental compatibility, process versatility and high efficiency. In addition, electrochemical treatment methods have been demonstrated to be very useful in the treatment of poorly biodegradable effluents. Studies have demonstrated that the electrochemical treatment efficiency is directly related to the electrode material. These materials should have electro-activity for reactions with the targeted pollutants, have high activation energy for undesired reactions and be corrosion resistant. Platinum and DSA® are known to be effective for the electro-oxidation of pollutants such as phenol, ammonia and ammonium ions. This work presents the results of a comparative evaluation of some materials that can be used as anodes for the electro-oxidation of ammonia and ammonium ions in petroleum refinery effluents. The selected materials were Pt, DSA®, Ni, anodized Al and graphite. Cyclic voltammograms confirmed the electro-activity of the Pt and DSA® electrodes and demonstrated the electro-activity of Ni. Anodic polarization revealed the electro-activity of graphite. Anodized Al electrodes showed no activity for the electro-oxidation of the analyzed compounds. The results for the Ni and graphite electrodes are promising.