天然斜发沸石吸附去除水中氨氮机理研究  

Mechanism of Ammonium Removal from Aqueous Solution by Natural Clinoptilolite

作　　者：黄晓鸣[1,2] 潘敏[1] 陈天虎[2] 朱木兰[1] 谢晶晶[2] 

机构地区：[1]厦门理工学院环境科学与工程学院,福建厦门361024 [2]合肥工业大学资源与环境工程学院,安徽合肥230009

出　　处：《矿物学报》2016年第3期371-376,共6页Acta Mineralogica Sinica

基　　金：福建省自然科学基金(批准号:2013J01210;2016J05140);中国博士后基金(编号:2014M560504);厦门市科技计划项目(编号:3502Z20130039);厦门理工学院对外科技合作交流专项(编号:E201401200)

摘　　要：采用天然斜发沸石吸附去除水中氨氮,利用X射线衍射(XRD)和X荧光光谱(XRF)分析沸石的物相组成和化学成分。通过批试验考察p H、氨氮初始浓度和温度对沸石吸附氨氮的影响,通过吸附等温线、吸附热力学和吸附动力学的研究探讨天然斜发沸石吸附氨氮的机理。溶液p H=8时沸石对氨氮的吸附效果最佳。Freundlich吸附等温线较Langmuir能更准确描述天然斜发沸石吸附氨氮的过程,该吸附过程属优惠吸附。对吸附热力学参数计算得到吉布斯自由能变ΔG^0<0,熵变ΔH^0>0,说明天然斜发沸石吸附氨氮是自发的吸热过程;熵变ΔS^0>0说明氨氮在沸石上的分布较在水溶液中的分布倾向无序。吸附动力学符合准二级动力学方程,且随着氨氮初始浓度的增大,吸附反应的优惠程度降低。运用颗粒内扩散模型对实验数据的拟合结果表明吸附过程分为两个阶段:前30分钟主要是外表面吸附,30分钟后主要是颗粒内扩散。This study investigated adsorption of ammonium from aqueous solution by natural clinoptilolite. The natural zeolite was characterized by X-ray diffraction（XRD） and X-ray fluorescence（XRF） for analysis of mineral phase and chemical composition. A series of experiments was conducted to examine the effects of p H, initial concentration of ammonium, and temperature on the removal of ammonium. To investigate the mechanism of the adsorption of ammonium by natural clinoptilolite, adsorption isotherms, kinetics and thermodynamics were studied. The results demonstrate that natural clinoptilolite shows good performance on ammonium adsorption under the condition of solution p H=8. Results show that ammonium adsorption on natural clinoptilolite is better to fit by Freundlich isotherm compared with Langmuir isotherm, and the adsorption process is favorable. Thermodynamic parameters such as Gibbs free energy change（ΔG^0）, enthalpy change（ΔH^0）, and entropy change（ΔS^0） were calculated. Negative value of ΔG^0 and positive value of ΔH^0confirm that ammonium adsorption on clinoptilolite is a spontaneous and endothermic process. Positive value of entropy change indicates that randomness increase during ammonium adsorption from aqueous solution onto zeolite surface. Kinetic studies show that the adsorption follows a pseudo-second-order reaction. The adsorption process is less favorable with increasing initial ammonium concentration. The fitting results indicate that the adsorption process could be divided into two stages, surface adsorption at initial 30 minutes and following inter-particle diffusion.

关 键 词：斜发沸石 吸附 氨氮 热力学 动力学 

分 类 号：P579[天文地球—矿物学] X754[天文地球—地质学]