Removal of ammonium from aqueous solution using NaCl modified zeolite.

In this study,natural zeolite pretreated by sodium chloride solution under thermal treatment was used to remove ammonium from aqueous solution.Adsorption kinetics,adsorption equilibrium isotherms and adsorption mechanism were investigated by conducting a series of batch experiments.The results indicated that NaCl modified zeolite exhibited higher ammonium adsorption capacity than natural zeolite.The kinetic studies showed that the adsorption of ammonium onto natural zeolite and NaCl modified zeolite could be described by the pseudo-second-order kinetic model and followed the intra-particle diffusion model only during the initial stage of the adsorption process.The results from adsorption equilibrium studies indicated that the Freundlich and Langmuir isotherm models were well fitted to experimental data.The maximum adsorption capacity of zeolite treated by 90 ℃ NaCl solution,zeolite treated by 30 ℃ NaCl solution,and natural zeolite were 19.5 mg/g,17.8 mg/g and 17.2 mg/g,respectively.The results also showed that the adsorption of ammonium from aqueous solution by the natural zeolite and the zeolite treated by NaCl solution is predominated by ion exchange,whereas physical adsorption has little influence.