法库沸石对氨氮的吸附特性和阳离子交互过程

以0.9~2 mm和3.3~4 mm粒径沸石的天然法库沸石作为实验材料,开展了等温吸附实验、动力学实验和阳离子影响实验,探讨了天然沸石对氨氮(NH4+-N)的吸附特性及阳离子交互过程。结果表明,法库沸石对NH4+-N等温吸附线符合Langmuir和Freundlich吸附方程,最大吸附量为10.41 mg/g。吸附动力学过程符合准二级和颗粒内经扩散动力学方程,其吸附NH4+过程为物理吸附和化学吸附过程,并以化学吸附为主。对反应过程中各离子浓度监测发现,沸石中与NH4+发生离子交换的主要是Na+、Ca2+和K+,三者占离子交换总量的99%。共存阳离子在沸石吸附NH4+过程中,Ca2+和Mg2+对吸附过程影响最大,Na+影响最小。

Adsorption characters of ammonium by Faku zeolite and cation exchanges in ammonium removal process

To study the characters and cation exchange processes of the adsorbed NH4+ into zeolite, Faku natural zeolite (0.9~2 mm and 3.3~4 mm) was selected as experiment material. According to the designed purpose, an isotherm adsorption experiment, an adsorption kinetics experiment and a cation influencing experiment were conducted, respectively. The results showed that in the isotherm adsorption experiment, the NH4+ into Faku zeolite demonstrated a good fit of Langmuir and Freundlich models, and the maximun adsorption capacity of NH4+ was 10.41mg/g. In the adsorption kinetics experiment, the NH4+ adsorption data were successfully described by the pseudo second-order kinetic model and the intraparticle diffusion equation, suggesting that the process of NH4+ into the Faku zeolite was both a physical and a chemical adsorption processes, and the latter played a dominant role. Based on the data obtained from the cation influencing experiment, the main exchange cations by NH4+ were Na+ , Ca2+ and K+, accounting for about 99% of the total exchange amount. Among the coexistent cations (K+, Na+, Ca2+, Mg2+), Ca2+ and Mg2+ showed a significant effect on NH4+ removal by zeolite, while Na+ exhibited a minimum effect on NH4+ removal.