Electrochemical regeneration of zeolites and the removal of ammonia

The electrochemical regeneration of zeolites was investigated with the objective of removing ammonia from water harmlessly and reusing the regeneration solution in an undivided electrochemical cell assembled with a Ti/IrO2-Pt anode and a Cu/Zn cathode. Zeolites could be completely regenerated through the electrochemical method in this study. With NaCl as a supporting electrolyte. the conversion rate of ammonia adsorbed by the zeolites into nitrogen gas was more that 96%, while the conversion rate to nitrate was less than 4%; no ammonia or nitrite was detected in the solution after electrolysis. The surface of the cathode appeared to be rougher after electrolysis than before. More nitrate was produced when the amount of NaCl was raised or when the current density was increased to the range of 20-60 mA/cm(2). The regeneration solution can be repeatedly reused over a long period of time with the proper amount of NaCl added to the solution. Even after the solution was reused for five times, it could still completely regenerate the zeolites, saving both water resources and the chemical reagent. (C) 2009 Elsevier B.V. All rights reserved.