天然沸石合成A型分子筛的吸附与再生特性

针对污水厂尾水深度脱氮问题，以某地产天然沸石为原料，采用水热合成法制备了纯度较高、晶型规整、大小均一、吸附量大的A型分子筛.系统考察了其对氨氮的吸附及再生特性，并结合Zeta电位、FTIR以及XRD对其氨氮吸附与再生机理进行了分析.结果表明：准一级和准二级反应动力学均能较好地反映A型分子筛吸附氨氮过程，等温吸附过程符合Langmuir等温吸附模型，对氨氮的最大饱和吸附量为41.68mg/g；吸附饱和的分子筛再生利用方法简便易行，经2mol/L NaCl溶液解吸后能够恢复其吸附能力，5次吸附-解吸再生率均在95%以上；其吸附与再生过程均为Na⁺与NH₄⁺的离子交换反应，吸附与再生互为可逆过程.该方法为污水厂深度脱氮提供了一条经济可行的新思路.

Adsorption and regeneration characteristics of type-A molecular sieve synthesized from natural zeolite

The deep denitrification problem of sewage plant effluent was addressed using type-A molecular sieve, with high purity, regular crystalline shape, uniform size, and large adsorption capacity. It was prepared by hydrothermal synthesis using natural zeolite. The ammonia adsorption and regeneration properties of such zeolitic molecular sieve were examined, and the related mechanisms were analyzed from Zeta potential, FTIR and XRD results. The results showed that both the quasi-first and quasi-second order reaction kinetics could well represent the ammonia nitrogen adsorption process, which can be described by the Langmuir isothermal adsorption model. The maximum saturated adsorption capacity of ammonia nitrogen reached 41.68mg/g. The regeneration of molecular sieve with adsorption saturation was simple and easy, and its adsorption capacity could be recovered after desorption by 2mol/L NaCl solution. The regeneration rate was above 95% after five cycles of adsorption and desorption. Both the adsorption and regeneration were reversible processes of each other, involving ion exchange reactions of Na⁺ and NH₄⁺. The application of zeolitic molecular sieves provided an economic and feasible new idea for the deep denitrification in sewage treatment plant.