NaCl改性沸石对水中氨氮的吸附机制

通过颗粒强度测定、扫描电镜分析（SEM）、X射线能谱分析（EDS）和零电点测定（pHPZC）考察改性前后沸石表面特性的变化，考察pH值、沸石投加量、初始氨氮浓度以及温度对吸附过程的影响，并通过吸附等温式和吸附动力学对吸附机制进行描述.经过NaCl改性后的沸石的颗粒强度明显增大，表面更加粗糙，孔径增大，钠离子通过交换作用进入到沸石内部.pH值为7，沸石投加量为8g/L，温度为35℃时吸附效果最好，平衡吸附量（qe）与氨氮初始浓度呈正相关性.Langmuir等温线比Freundlich等温线更适合描述实验数据，最大饱和吸附量为13.210mg/g.吸附动力学符合准二级动力学模型.实验表明NaCl改性沸石能够有效去除水中的氨氮.

Adsorption mechanism of ammonium from aqueous solutions by NaCl modified zeolite

Surface morphology of zeolite before and after modified was analyzed through the particle strength, scanning electron microscope (SEM) and energy dispersive spectroscopy (EDS) and point of zero charge (pHPZC). Adsorption studies were carried out at different pH, zeolite dosage, initial ammonium concentrations and temperature. Adsorption mechanism was measured through the adsorption isotherm and adsorption dynamics. The feature of NaCl modified zeolite included increased particle strength, a rough surface, and enlarged pore size. It was also found that sodium ions would enter the zeolite internal through ion exchange. The experimental results showed that the best adsorption condition was pH value of 7, zeolite dosage of 8g/L and temperature at 35℃. The study also revealed that equilibrium adsorption capacity (qe) was positive correlation with initial ammonium concentration. Adsorption data was fitted better to Langmuir adsorption isotherms, with maximal adsorption capacity of 13.210mg/g. The results of kinetics study indicated that the pseudo-second-order model fitted to the experimental data well. These results therefore proved that NaCl modified zeolite could be effectively used as a low-cost adsorbent for the removal of ammonium from wastewater.