Optimization of electrochemical ammonia removal using Box–Behnken design

Electrochemical oxidation of ammonia in an undivided cell was studied in the present experiments. The optimization of the influencing factors on electrochemical removal of ammonia by response surface methodology (RSM) was also studied. Ammonia could be effectively removed by electrochemical method, and which was mainly oxidized into harmless nitrogen gas. The Box–Behnken design can be employed to develop mathematical models for predicting electrochemical ammonia removal geometry. The desired electrochemical ammonia removal can be achieved by choosing the predicted conditions using the developed models. In the present experiments, the optimal NaCl dosage, current density and electrolysis time are 0.31 g/L, 42.75 mA/cm2, and 100.64 min, respectively, at which the ammonia-N and nitrate-N concentration in the treated solution are 0 and 1.1 mg/L, respectively, which will meet the standards for drinking water.

► The combination of Ti/IrO2 as anode and Cu–Zn as cathode for electrochemical ammonia removal was studied.
► The application of RSM only focusing on the removal of ammonia by electrochemical method in an undivided cell was studied.
► RSM was used to determine the optimal condition and an empirical model correlating the ammonia removal efficiency to the three variables was developed.