两性复配修饰土对有机、重金属污染物的同时吸附及构效机制

The prevention and treatment on the complex pollution of both organics and heavy metals(HM) plays an important role on the protection of soil, underground water, crops and human's health. This project is a continue and farther research based on the achievements of our previous project supported by nsfc. In this project, using 3 kinds of clays, montmorillonite, kaolinite and goethite, as the materials, we will prepare amphoteric-combine-modified-clay(ACMC) with amphoteric modifier duodalkylbetaine(BS12) coupled with 3 kinds of combine modifiers, i.e. amphoteric-cationic, amphoteric-anionic and amphoteric-nonionic modifier, and the systematic reseaches about the effect of amphoteric-combine-modification on simultaneous adsorption of organic-HM complex polltant, Phenanthrene+Cadmium(II) or Phenanthrene+Chromate, in ACMC, about how the combined styles between amphoteric-combine-modifier and clay affect surface characteristics, microstructure and stablity of ACMC will be conduted. The purpose is to reveal adsorption mechanism of organic-HM complex polltant on ACMC, and to build the structure-effect relationship between mechanism of amphoteric-combine-modification, characteristics of clay's surface and microstructure, simultaneous adsorption of organic-HM complex polltant and stablity of ACMC. The confirmation of the structure-effect relationship will be studied also by applying the outcomes in actural soils. On the foundation above, we attempt to reveal the intrinsic characteristics of ACMC, and to establish a mechanism for microscopic regulating and controlling to ACMC's simultaneous adsorption ability. Finally, we can propose theoretical evidences for simultaneous recovery and treatment of organic and HM complex pollution in soil modified with amphoteric-combine-modifier.

土壤中有机物、重金属复合污染防治的研究对于保护土壤、地下水、农作物和人体健康具有重要意义。本项目在前期基金研究的基础上，以不同类型黏土矿物（蒙脱土、高岭土和针铁矿）为基质，将两性修饰剂BS-12分别与阳离子型、阴离子型和非离子型表面修饰剂复配对不同类型黏土矿物进行修饰，系统地研究两性复配黏土矿物对菲+镉离子或菲+铬酸根复合污染物的同时吸附效应，修饰剂与黏土矿物的结合模式及对两性复配黏土矿物表面特征、结构特征和稳定性的影响。目的在于揭示两性复配修饰黏土矿物对复合污染物的吸附机制，建立起复配修饰机制、表面和结构特征、有机物和重金属同时吸附效应、修饰黏土矿物稳定性之间的结构与效应关系，并应用于不同电荷类型的土壤中进行验证，在此基础上揭示两性复配修饰土的内在特征，力图确立两性复配修饰土吸附能力的微观调控机制，为土壤中有机物、重金属复合污染的同时修复及防治提供理论依据。

本项目在前期基金研究基础上，将两性修饰剂BS-12分别与阳离子型、阴离子型和非离子型修饰剂复配对不同类型黏土矿物（膨润土、高岭土和针铁矿）进行修饰，系统地研究两性复配修饰黏土矿物对有机（苯酚或菲）和重金属（Cd2+或Cr（VI））污染物的吸附效应，修饰剂与黏土矿物的结合模式及对两性复配黏土矿物表面特征、结构特征和稳定性的影响，并应用于不同电荷类型的土壤中进行验证。研究发现，两性复配修饰有效的增强了对有机物、重金属的吸附，对苯酚（菲）、Cd2+和Cr（VI）的吸附能力比BS修饰土提高9.47、3.11、36.8倍，阳离子复配适用于增强苯酚和Cr（VI）的吸附，阴离子复配适用于增强对Cd2+、Cr（VI）的吸附，但非离子型复配增强作用不大；碳链长度增加有助于对苯酚（菲）和Cr(Ⅵ)的吸附，但阴离子复配表现出中等碳链的最佳效应；筛选得到对苯酚、Cd2+和Cr（VI）的最佳修饰模式分别为100BS-100CTMAB、100BS-150SDS和50BS-150SDS。膨润土和高岭土的吸附效应一致，但与针铁矿差异较大，吸附效应具有膨润土>高岭土>针铁矿的顺序。除低比例的阴离子复配修饰外，随修饰比例增加两性复配黏土矿物的TOC增加，比表面积、CEC减小；膨润土的复配修饰是插层修饰，而高岭土、针铁矿上均是外表面修饰。对离子交换、疏水初现和疏水优势模式的BS膨润土、BS高岭土的复配修饰，阳、阴离子修饰剂出现疏水修饰转折点分别为30.40%～-3.34% CEC、16.80%～0.68% CEC和15.93%～0%CEC、0% CEC，碳链长度增加减小了疏水修饰的临界比例。阳、阴离子复配修饰具有较高的稳定性，但随两性、复配修饰比例的增加和碳链长度的减小而减小。两性复配在实际土壤中的应用证实了最佳修饰形式和比例的有效性。研究结果对于提高土壤吸附有机、重金属能力，开发新型吸附材料具有实际意义和应用前景。