选择性去除水中重金属的高效磁性LDH复合材料的设计合成及性能研究

It is important to design and synthesis highly efficient adsorbent for selective removal of heavy metals from aqueous solution. This can provide some kinds of new materials to treat heavy metal wastewater.. This proposal will conduct: (1) preparation of highly efficient magnetic LDH composites. Some organic ligands, amino acids and nature polymers often have functional groups which able to chelate heavy metals, such as thiol, amino, carboxyl, sulfonic and etc, then Fe3O4@LDH will be intercalated by these materials to form functionalized adsorbent for highly efficient and selective removal of heavy metals from aqueous solution. The measurements of XRD, BET, SEM, TEM, FTIR, VSM and Zeta potential will be used to characterize the structure and surface properties. (2) adsorption behavior of heavy metals of lead, cadmium, mercury and hexavalent chromium. The experiments include effects of conditions, adsorption kinetics, adsorption isotherm and adsorbent regeneration. (3) mechanisms of heavy metal adsorption by functionalized magnetic LDH composite. We will focus on the characterization of composites by ATR-FTIR, XPS and XRD, analysis of LDH-water interface by acid-bade titration and Zeta potential determination before and after adsorption to clarify the adsorption and design mechanisms.. We hope to elucidate the strategy of functionalized magnetic LDH composites design for highly efficient and selective removing heavy metals with easy magnetic separation. It also can provide some theoretical basis on heavy metal wastewater treatment.

设计合成选择性去除水中重金属离子的高效吸附剂，是用于水体重金属污染治理、改善水环境质量的功能材料之一。本项目充分利用LDH的层间可调控性，拟采用插层、膨润/回复、层离/自组装等方法，将含有巯基、氨基、羧基、磺酸基等基团的物质与Fe3O4@LDH核壳结构进行复合，设计合成多种选择性去除重金属的高效磁性LDH复合材料，运用XRD、FTIR、BET、SEM、TEM、VSM、Zeta电位等手段对其结构与表面性质进行表征；以环境中典型重金属铅、镉、汞和六价铬为代表污染物，进行吸附实验，考察吸附容量、选择性、回收利用等性能；运用多种谱学手段（XRD、ATR-FTIR、XPS）和界面化学方法（电位滴定、Zeta电位），从吸附位点、表面络合等方面研究重金属吸附的微观机理，验证材料设计原理。希望确定选择性去除重金属的易磁分离的高效LDH复合材料设计策略，为去除重金属的功能材料设计与应用提供理论基础。

本项目以高效选择性去除水中重金属离子为目标，充分利用LDH的层间与表面可调控特性，采用水热、插层、交联、煅烧等方法，将含有功能基团的物质，如氧化石墨烯、氨基酸、壳聚糖、EDTA、海藻酸盐、TiO2等与LDH复合，设计制备了多种LDHs复合材料，采用XRD、FTIR、XPS、BET、SEM、TEM等手段对材料的结构与性质进行了表征，结果表明，复合材料不仅保留了二维LDH的晶体结构，而且具备了提高吸附能力的功能基团。提出了负载Fe3O4到矿物材料制备磁性材料的溶剂热方法，过程简单易控，不仅保持了矿物材料本身的结构，还负载了氨基、羟基等官能团，提高了磁性矿物材料去除水中污染物的能力，且具备超顺磁性，利于吸附后的吸附剂快速固液分离与回收利用。.以水中典型重金属Pb(II)、Cd(II)、Cu(II)、Cr(VI)和磷酸盐为代表污染物，进行了磁性LDHs等材料吸附的动力学、等温线、解吸作用、重复利用等性能研究，结果表明LDHs复合材料和磁性矿物材料有效提升了水中污染物的去除能力。如将磁性LDH吸附水中的腐殖酸类物质后的废弃吸附剂，通过简便的高温煅烧后得了磁性LDO/碳复合材料，其对水中Cd(II)、Pb(II)、Cu(II)的最大吸附量分别为386.1、359.7、192.7 mg/g，且对实际水样中重金属具有很好的吸附能力和重复利用性。综合运用FTIR、XRD、XPS等多种谱学手段和zeta电位测定等界面化学方法，重点研究了吸附后的LDHs复合材料的改变，从吸附位点、材料结构、表面性质等角度，阐明了表面络合、沉淀作用、静电作用、同晶置换等微观作用机制，为去除重金属的功能材料设计与应用提供了理论基础。.通过本项目的研究，以通讯作者发表论文17篇，授权发明专利5项，已毕业硕士研究生9人。