Kinetic study of electrolytic ammonia removal using Ti/IrO2 as anode under different experimental conditions.

This study reports electrolytic degradation and kinetic modeling of electrolytic degradation of ammonia using Ti/IrO(2). The experimental and modeling results are compared with those previously obtained using Ti/RuO(2) anode. Synthetic solution containing predetermined ammonia concentration and the raw municipal wastewater collected after the aerobic or the anaerobic treatment were used in different sets of experiments. The experimental conditions varied for electrolytic degradation of ammonia present in the synthetic feed were initial chloride concentration, initial pH and applied current density. The results show that the ammonia removal followed pseudo zero-order kinetics. The current density (j) and the initial Cl(-) concentration ([Cl(-)]) affected the constant of the pseudo zero-order kinetics, expressed as k(Ti/IrO(2))=0.0020[Cl-]j + 0.4848 and k(Ti/RuO(2))=0.0026[Cl-]j - 0.7417. The ammonia removal rate averaged at 8.5 using Ti/IrO(2) and was comparable to the rate (11.7 mg N L(-1)h(-1)) obtained using Ti/RuO(2) anode, at 15.4 mA cm(-2) current density, 300 mg L(-1)Cl(-) and pH of 7. Higher current density and as well as the chloride concentration resulted in greater ammonia degradation. On the other hand, pH did not seem to have any effect on electrolytic degradation of ammonia. More than 95% ammonia degradation in municipal wastewater effluents collected after aerobic or anaerobic treatment was achieved. The ammonia nitrogen in the electrolytically treated wastewater effluents collected at the end of aerobic and anaerobic environments were 0.9, 0.5 mg N L(-1) using Ti/IrO(2) and 0.5, 0.2 mg N L(-1) by using Ti/RuO(2) anodes, respectively.