巯基改性坡缕石的制备、表征及其对Cd的吸附作用

为明确巯基改性坡缕石(MPAL)作为修复材料对Cd的吸附机制以及其在修复Cd污染土壤中的应用潜力，以坡缕石(PAL)为原料，通过高速剪切凝胶法制备MPAL作为钝化剂开展吸附试验与土壤钝化试验，研究MPAL对Cd的吸附效果.通过X射线衍射(XRD)、BET孔结构分析、傅里叶红外光谱(FTIR)、扫描电子显微镜(SEM)以及X射线光电子能谱(XPS)对吸附前后的样品进行表征，探讨其吸附机制.结果表明：PAL和MPAL均能有效吸附水溶液中的Cd²⁺,MPAL吸附效果优于PAL.拟二级动力学模型更适合描述Cd²⁺在PAL和MPAL上吸附量的动态变化过程，MPAL约90 min达到吸附平衡，相比于PAL能更加迅速达到吸附平衡. Freundlich等温吸附模型能够更好地描述吸附数据特征，在试验条件下，MPAL的饱和吸附容量为44.41mg/g，明显高于PAL的饱和吸附容量(33.65 mg/g). MPAL在投加量为0.1%～0.3%时可使土壤DTPA提取态Cd含量降低53.45%～78.43%. XRD衍射峰分析、FTIR官能团振动模式分析以及XPS...

Preparation and Characterization of Sulfhydryl Modified Palygorskite and Their Application for Cadmium Adsorption

In order to understand the adsorption mechanism of Cd by sulfhydryl modified palygorskite (MPAL) as a remediation material and its application potential in the remediation of Cd-contaminated soil, MPAL was prepared by high speed shear gel method using palygorskite (PAL) as raw material to carry out adsorption experiments and soil passivation experiments, and the adsorption effect of MPAL on Cd was studied. X-ray diffraction (XRD), BET pore structure analysis, Fourier transform infrared spectroscopy (FTIR), scanning electron microscopy (SEM) and X-ray photoelectron spectroscopy (XPS) were used to characterize the samples before and after adsorption, and to explore the adsorption mechanism. The results showed that both PAL and MPAL could effectively adsorb Cd2+ in aqueous solution, and the adsorption effect of MPAL was better than PAL. The pseudo second order kinetics model is more suitable to describe the dynamic change process of Cd2+ adsorption on PAL and MPAL. MPAL reaches the adsorption equilibrium in about 90 minutes, which is faster than PAL. Freundlich isotherm absorption can describe the adsorption data better. Under the experimental conditions, the saturated adsorption capacity of MPAL is 44.41 mg/g, which is significantly higher than that of PAL (33.65 mg/g). The DTPA extractable Cd concentrations in soil can be reduced by 53.45%-78.43% when the dosage of sulfhydryl modified palygorskite is 0.1%-0.3%. X-ray diffraction peak analysis, FTIR functional group vibration mode analysis and binding energy analysis of key elements of XPS showed that PAL adsorbed Cd through the formation of surface complexation between the surface hydroxyl group and Cd2+, while MPAL also provided a large number of sulfhydryl functional groups as adsorption sites, and formed complexation precipitation through the complexation reaction between the surface hydroxyl group and the sulfhydryl group and Cd2+. The study showed that MPAL has stronger adsorption capacity for Cd, and it is an efficient passivating agent with good application potential in Cd polluted farmland soil.