巯基功能化大孔二氧化硅的制备及其对土壤中二乙三胺五乙酸(DTPA)提取态Cd、Pb的钝化性能

Preparation of thiol groups modified macroporous structured nano-silica and its immobilization of Cd and Pb in contaminated soils

以硅酸钠为前驱体,分别制备表面带有氨基和环氧基团的纳米二氧化硅,利用氨基和环氧基团的桥接反应构建具有大孔结构的纳米二氧化硅,进一步在其表面负载具有重金属反应性的巯基基团,最终得到一种具有重金属高效反应性的纳米材料,并将其用于对土壤重金属的钝化修复.红外光谱、透射电镜、比表面积等分析显示,氨基和环氧基有机基团的修饰降低了纳米二氧化硅颗粒之间的团聚,两种基团之间的架桥反应,构建了具有较大孔径的二氧化硅聚集结构.通过研究改性二氧化硅对污染土壤中DTPA提取态Cd、Pb的钝化作用,发现巯基修饰的大孔径纳米二氧化硅(SiO_(2)-AE/SH)大幅提高了对重金属的钝化率;在添加比例为4%,修饰剂量为1.10 mmol·g^(−1)时,SiO_(2)-AE/SH对Cd的钝化效率是巯基修饰纳米二氧化硅(SiO_(2)-SH)的1.28倍,对Pb的钝化效率是SiO_(2)-SH的3.31倍.此研究为构建高效、大孔结构重金属钝化材料提供了一种方法,此材料也有望发展成为多孔硅过滤介质,应用于重金属废水处理.

Sodium silicate is used as the precursor to prepare nano-SiO_(2)with amine and epoxy groups on the surface. Two kinds of SiO_(2)are bridged through the reaction between amino and epoxy groups to build nano-SiO_(2)with macroporous structure. Thiol groups with heavy metal reactivity were further loaded on its surface to afford a type of highly reactive SiO;nanomaterial for immobilization of heavy metals in soils. FTIR, TEM, and specific surface area analysis show that the modification of amino and epoxy organic groups reduces the agglomeration between nano-SiO;particles, and the bridging reaction between amino and epoxy groups help construct a macroporous aggregated SiO_(2)structure. By studying the immobilization effect of modified SiO_(2)on the effective states of Cd and Pb in contaminated soils, the thiol-modified macroporous nano-SiO_(2)greatly can improve the immobilization rate of heavy metals. When the addition ratio is 4% and the modification dosage is 1.10 mmol·g^(-1), the immobilization efficiency of SiO_(2)-AE/SH to cadmium ions and lead ions is 1.28 times and 3.31 times than that of SiO;-SH, respectively. This research provides a method for constructing high-efficiency, large-pore structure nanomaterials for heavy metal passivation, and this material is also expected to play roles in the treatment of heavy metal wastewater as porous silicon filter.