Optimization of ammonia removal by ion-exchange resin using response surface methodology

The ability of ion-exchange resin for ammonia removal from aqueous solution was studied. The results showed that Amberlite ion-exchange resin was effective in removing ammonia from aqueous solution. Factorial design and response surface methodology were applied to evaluate and optimize the effects of pH, resin dose, contact time, temperature and initial ammonia concentration. Low pH condition was preferred with the optimum pH found to be 6. High resin dose generated high removal rate and low exchange capacity. Results of factorial design and response surface methodology showed that temperature was not a significant parameter. The model prediction was in good agreement with observed data (R-2 = 0.957). The optimum Q(e) was 28.78 mg/g achieved at pH = 6 and initial TAN concentration of 3000 mg/L. The kinetics followed the pseudo-second-order kinetic model (R-2 = 0.999). Equilibrium data were fitted to Langmuir and Freundlich isotherm models with Langmuir model providing a slightly better predication (R-2 = 0.996). The resin was completely regenerated by 2 NH2SO4.