改性天然沸石的制备及对氨氮的吸附

Modification of Natural Zeolite and Adsorption of Ammonia Nitrogen by Modified Natural Zeolite

在不同温度及超声辐射条件下,用NaCl溶液浸泡天然沸石来对其进行表面改性,以强化其对氨氮的吸附.应用静态吸附法分别测定了氨离子在天然沸石和美国产Champion、中国台湾产AZOO沸石和改性沸石上的吸附离子交换等温线,并探讨了溶液pH值、焙烧温度和浸泡方法对沸石吸附氨氮的影响.研究结果表明：天然沸石吸附氨氮的最佳pH值范围在3～9之间,吸附过程以离子交换作用为主;高温焙烧会引起沸石脱水,从而导致孔壁坍塌,使沸石孔径增大,比表面积减小,降低了对氨氮的吸附交换能力;经98℃NaCl溶液浸泡后,沸石中Na^＋的含量增加,沸石对氨氮的吸附交换容量明显增大,超过了美国产Champion沸石和中国台湾产AZOO沸石.

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 isotherms 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 solutions 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 weakening the adsorption and ion exchange capacities, and （4） the soaking by NaCl aqueous solution at 98 ℃ increases 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.