Research on the Treatment of Ammonia-nitrogen Wastewater by Lead Dioxide Power Porous Electrode

Pure PbO₂ electrode and PbO₂ powder porous electrode which was modified by adding graphite and activated carbon powder, were prepared by high pressure molding. The electrode properties were evaluated by means of SEM and cyclic voltammetry. Furthermore, the electrocatalytic property was further examined through the treatment of ammonia-nitrogen wastewater. It was showed that PbO₂ powder porous electrode was better in view of electrical conductivity and electrocatalytic activity and the optimum mass percentage of graphite and activated carbon powder was 15% to 20%. Removal efficiency of ammonia nitrogen was improved continuously with increasing current density and increasing concentration of chloride ion added. Besides, ammonia-nitrogen removal efficiency reduced continuously with increasing pH when the initial pH was between 3.0-10.0, but increased when that was between 11.0-12.0. The treatment of ammonia-nitrogen wastewater by PbO₂ powder porous electrode was due to strong oxidizing substances, such as ·OH, HClO and ClO^-, which were produced by the electrocatalytic activity of anode, and the ammonia-nitrogen was finally oxidized into NO_x gas mainly with N₂ and with small amount of nitrate nitrogen.