Efficient treatment of ammonia-nitrogen contaminated waters by nano zero-valent iron/zeolite composite

The aim of the present study is developing a magnetic nanoscale zero-valent iron/zeolite (nZVI/Z) composite towards the efficient removal of ammonia-nitrogen (NH4+-N) from aqueous solutions. Series of batch experiments were conducted to investigate the effect of different factors on the removal efficiency, including pH effect, aerobic/anaerobic, NH4+-N initial concentration, and temperature. The mixing mass ratio of nZVI/Z was optimized to reach the optimal ratio (0.25 g nZVI: 0.75 g zeolite), corresponding to the best removal efficiency of 85.7% after 120 min of reaction. Results revealed that nZVI/Z is efficient for NH4+-N removal from water at a wide pH range (3.0–10.0), with superiority to the neutral conditions. Moreover, aerobic ambient and normal temperature of 25 °C were the optimal conditions for the removal process of NH4+-N. Removal mechanisms involved electrostatic attraction, ion exchange, and adsorption. Generally, nZVI/Z has great potential towards the practical applications of NH4+-N removal from water.