Abstract:

In order to improve the adsorption of ammonia nitrogen by zeolite , NaCl aqueous solution was used to soak natural zeolite at different temperatures under ultrasonic radiation. The adsorption/ion-exchange isothems of ammonia nitrogen respectively on natural zeolite , American Champion zeolite , Taiwan' s AZOO zeolite and the modified zeolite were then measured by means of static adsorption , and the effects of pH value , baking temperature
and soaking conditions on the adsorption were discussed. The results indicate that (1) the optimal pH value of so-lutions for the adsorption of ammonia nitrogen on the natural zeolite is 3~9; (2) the adsorption is mainly ascribed to the role of ion exchange; (3) the baking of zeolite at high temperature leads to a framework collapse due to the water loss in structural chains , thus increasing the average pore size , decreasing the specific surface area and wea-kening the adsorption and ion exchange capacities , and (4) the soaking by NaCl aqueous solution at 98℃ increa-ses the Na ⁺ content in zeolite and greatly improves the ion exchange capacity for ammonia nitrogen , which is higher than those of American Champion zeolite and Taiwan' s AZOO zeolite.

Key words: zeolite, surface modification, ammonia nitrogen, adsorption, ion exchange