巯基改性蒙脱石对Cd(Ⅱ)的吸附机理研究  

Mechanism Study of Cadmium(Ⅱ) Adsorption on Thiol-Modified Montmorillonite

作　　者：朱霞萍[1] 刘慧[1] 谭俊[1] 刘文华[2] 冯超[2] 

机构地区：[1]成都理工大学材料与化学化工学院,四川省矿产资源化学高校重点实验室,四川成都610059 [2]广东省物料实验检测中心,广东广州510080

出　　处：《岩矿测试》2013年第4期613-620,共8页Rock and Mineral Analysis

基　　金：国土资源部公益性行业科研专项项目(201111016-2);广东省财政厅地质专项(2011208);横向委托项目(HP0030)

摘　　要：蒙脱石对镉有良好的吸附性,但吸附力较弱,巯基改性蒙脱石可增强对镉的吸附,而关于蒙脱石的巯基改性及改性后对镉的吸附机理研究少见报道。本文以(3-巯丙基)三甲氧基硅烷作为改性剂,采用简单的溶液法对蒙脱石原土(简称MMT)进行巯基改性,并探讨了改性蒙脱石(简称MMT-SH)对镉的吸附机理。红外和X射线衍射表征显示MMT被成功接上巯基。吸附条件实验表明,MMT-SH对Cd(Ⅱ)的吸附效果显著优于原土,对Cd(Ⅱ)的饱和吸附容量是原土的39倍;吸附容量受pH值影响大,受离子强度的影响较大;MMT-SH对Cd(Ⅱ)的吸附作用除了静电吸附、离子交换吸附、羟基配位吸附,还主要存在巯基配位吸附。热力学及动力学实验表明,MMT-SH吸附Cd(Ⅱ)的反应符合Langmiur等温模型和Lagergren二级动力学方程,是易于发生的化学反应;吸附过程的热力学参数(ΔH、ΔG、ΔS)表明此吸附是一个自发的吸热过程。Montmorillonite （MMT） is a good sorbent of cadmium, but the adsorbability is weak. Thiol-Modified Montmorillonite could increase the adsorption of cadmium, but the studies about thiol-modified montmorillonite （MMT-SH） and the adsorption mechanism of cadmium on MMT-SH are rarely reported. In this study, the MMT-SH was prepared through modifying natural MMT with 3-mercapto-propyl-trimethoxysilane and the adsorption mechanism of cadmium on MMT-SH was investigated. The characteristic results of FT-IR and XRD indicated the successful tethering of the thiol group on MMT. The experimental results of cadmium adsorption on MMT-SH showed that the adsorption efficiency of cadmium on MMT-SH was much better than that on natural MMT, which had been increased 39 times. Adsorption efficiency was influenced by ionic strength and pH value of the system. Except for electrostatic adsorption, ion-exchange and hydroxyl coordination, the thiol coordination was one of the main reactions in adsorption of cadmium on MMT-SH. The adsorption behavior of cadmium on MMT-SH fitted well with the Langmuir adsorption isotherm and Lagergren-second-order kinetic model which indicates that the adsorption is a chemical process. The thermodynamic parameters （ΔH, ΔG and ΔS） show that the adsorption of cadmium on MMT-SH is a spontaneous endothermic process.

关 键 词：蒙脱石 巯基改性 镉 吸附机理 

分 类 号：TU52[建筑科学—建筑技术科学] O614.242[理学—无机化学]