THE ADSORPTION CHARACTERISTICS OF SALT MODIFIED ZEOLITE TO AMMONIA NITROGEN

To improve the adsorption capacity of natural zeolite for ammonia nitrogen, zeolite was modified by sodium chloride (NaCl), sodium tungstate (Na2WO4), and sodium citrate (C6H5Na3O7) solutions, and the adsorption characteristics of zeolite before and after modification for ammonia nitrogen in water were studied. The properties and structure of zeolite were characterized and analyzed. The adsorption mechanism of modified zeolite for ammonia nitrogen and the effects of environmental factors on the adsorption were studied. The results showed that the modification of NaCl, Na2WO4, and C6H5Na3O7 increased the adsorption capacity of zeolite by 60.76%, 58.23%, and 54.43%, respectively. The zeolite modified by NaCl solution had the best adsorption effect for ammonia nitrogen. The optimum concentration, temperature, and time of NaCl modifier was 1.5 mol/L, 85 degrees C, and 12 h. The adsorption of ammonia nitrogen on zeolites before and after modification was more consistent with the pseudo-secondorder kinetic model. Under the conditions of particle size of 60-80 mesh, pH of 7, temperature of 30 degrees C, and dosage of 10 g/L, the removal rate of ammonia nitrogen by zeolites increased from 54.89% to 90.39% after adsorption of wastewater with initial ammonia nitrogen concentration of 50 mg/L. The adsorption of ammonia nitrogen in wastewater by natural zeolite modified by salt solution is an environmentally friendly and effective method.