"Petru Poni" Institute of Macromolecular Chemistry, Grigore Ghica Voda Alley 41 A, 700487 Iasi, Romania.
Faculty of Chemistry, "Al. I. Cuza" University of Iasi, Bd. 11 Carol I, 700506 Iasi, Romania.
Molecules. 2020 Mar 10;25(5):1249. doi: 10.3390/molecules25051249.
Removal of Cr(VI) from the environment represents a stringent issue because of its tremendous effects on living organisms. In this context, design of sorbents with high sorption capacity for Cr(VI) is getting a strong need. For this purpose, poly(vinylbenzyl chloride), impregnated into porous silica (PSi), was cross-linked with either ,,','-tetramethyl-1,2-ethylenediamine (TEMED) or ,,','-tetramethyl-1,3-propanediamine, followed by the reaction of the free -CHCl groups with ,-diethyl-2-hydroxyethylamine to generate strong base anion exchangers (ANEX) inside the pores. The PSi/ANEX composite sorbents were deeply characterized by FTIR spectroscopy, SEM-energy dispersive X-ray spectroscopy (EDX), thermogravimetric analysis (TGA), and water uptake. The sorption performances of composites against Cr(VI) were investigated as a function of pH, contact time, initial concentration of Cr(VI), and temperature. It was found that the cross-linker structure and the silica morphology are the key factors controlling the sorption capacity. The adsorption process was spontaneous and endothermic and well described by pseudo-second-order kinetic and Sips isotherm models. The maximum sorption capacity of 311.2 mg Cr(VI)/g sorbent was found for the composite prepared with mesoporous silica using TEMED as cross-linker. The PSi/ANEX composite sorbents represent an excellent alternative for the removal of Cr(VI) oxyanions, being endowed with fast kinetics, equilibrium in about 60 min, and a high level of reusability in successive sorption/desorption cycles.
从环境中去除 Cr(VI) 是一个严峻的问题，因为它对生物体有巨大的影响。在这种情况下，设计对 Cr(VI) 具有高吸附能力的吸附剂变得非常必要。为此，将聚(氯化 vinylbenzyl)浸渍到多孔硅 (PSi) 中，然后用,,','-四甲基-1,2-乙二胺 (TEMED) 或,,','-四甲基-1,3-丙二胺交联，接着将游离的 -CHCl 基团与,-二乙基-2-羟乙基胺反应，在孔内生成强碱阴离子交换剂 (ANEX)。PSi/ANEX 复合吸附剂通过傅里叶变换红外光谱 (FTIR)、扫描电子显微镜-能量色散 X 射线光谱 (SEM-EDX)、热重分析 (TGA) 和吸水率进行了深入表征。研究了复合材料对 Cr(VI) 的吸附性能，考察了 pH、接触时间、Cr(VI)初始浓度和温度等因素的影响。结果表明，交联剂结构和硅的形态是控制吸附能力的关键因素。吸附过程是自发的和吸热的，准二级动力学和 Sips 等温线模型可以很好地描述。发现使用 TEMED 作为交联剂制备的介孔硅复合材料的最大 Cr(VI)吸附容量为 311.2 mg Cr(VI)/g 吸附剂。PSi/ANEX 复合吸附剂是去除 Cr(VI) 阴离子的一种极好的替代品，具有快速的动力学特性，约 60 min 即可达到平衡，在连续的吸附/解吸循环中具有很高的可重复使用性。
