十二烷基磺酸钠(SDS)改性蒙脱石对Cu^(2+)、Cd^(2+)的吸附研究

Adsorption of Cu^(2+) and Cd^(2+) by SDS-modified montmorillonite

以阴离子表面活性剂(十二烷基磺酸钠,SDS)为改性剂制备了有机蒙脱石,研究其对Cu2+、Cd2+的吸附行为,并用XRD、FTIR、SEM、XPS对有机蒙脱石进行表征.实验结果表明,有机蒙脱石对Cu2+、Cd2+的吸附基本上在20min内达到平衡,并随pH增大(1.0～7.0),吸附量增加,最佳pH约为6.0.有机蒙脱石对Cu2+、Cd2+的吸附等温线更符合Langmuir等温吸附方程,SDS改性蒙脱石对Cu2+、Cd2+的最大吸附量较纯蒙脱石分别增加15.7%、15.5%.XRD、FTIR、SEM、XPS及碳含量分析结果显示,SDS主要分布在蒙脱石表面且相对稳定,少量嵌入层间,有机蒙脱石对Cu2+、Cd2+的吸附机制为配位吸附和离子交换.

The adsorption of Cu^2＋ and Cd^2＋ onto montmorillonite modified with an anionic surfactant （sodium dodecylsulfate,SDS） was investigated. The organic montmorillonite was examined by Fourier transform infrared spectroscopy （FTIR）, X-ray diffraction （XRD）, scanning electron microscopy （SEM） and X-ray photoelectron spectroscopy （XPS）. The adsorption of Cu^2＋ and Cd^2＋ onto montmorillonite reached equilibrium basically within 20 min, and the adsorption capacity increased with increasing solution pH （1.0-7.0） with the optimum pH being 6.0. The adsorption isotherms of Cu^2＋ and Cd^2＋ were modelled with the Langmuir equation. The maximum adsorption capacities for Cu^2＋ and Cd^2＋ onto SDS-modified montmorillonite were 15.7% and 15.5% more than onto purified montmorillonite. The results of XRD, FTIR,SEM, XPS and the analysis of carbon content revealed that the SDS was mainly distributed on the surface of montmorillonite, with a small amount intercalated into the interlayers. The mechanisms of adsorption of Cu^2＋ and Cd^2＋ onto organic montmorillonite were mainly coordination and ion exchange.