氨基改性MCM-41对水中1,2-二氯乙烷的吸附

为治理地下水中氯代烃污染，以3-氨丙基三乙氧基硅烷(APTES)为改性试剂，采用共聚法制备NH₂-MCM-41。利用XRD、SEM、TEM、BET和FT-IR对材料结构进行表征，并研究材料对水中1,2-二氯乙烷(1,2-DCA)的吸附行为。结果表明：氨基取代部分硅羟基，造成孔道毛糙，未改变材料的六方堆积结构；改性后材料比表面积、孔容、孔径分别减小了约10%、25%和26%。
氨基的引入增强了材料对1,2-DCA的亲和力和吸附能力，吸附容量由11.75 mg·g⁻¹增加到15.59 mg·g⁻¹，提升32.68%；NH₂-MCM-41对1,2-DCA吸附初始阶段受物理吸附控制，后续过程主要受化学吸附控制；颗粒内扩散拟合表明颗粒内扩散过程是主要控速步骤；等温吸附拟合说明材料吸附位点分布均匀，吸附过程中单层与多层吸附共存；在温度为20 ℃，pH为7时NH₂-MCM-41对1,2-DCA的吸附效果最佳；腐殖酸(HA)和共存阴离子对 NH₂-MCM-41吸附1,2-DCA起抑制作用。由此可知，NH₂-MCM-41能够有效地吸附水中1,2-DCA。该研究成果可为地下水氯代烃污染治理提供相关参考。

Adsorption of 1,2-dichloroethane in water by amino modified MCM-41

In order to control the pollution of chlorinated hydrocarbons in groundwater, NH2-MCM-41 was prepared by copolymerization with 3-aminopropyltriethoxysilane (APTES) as the modifier. The structure of NH2-MCM-41 was characterized by XRD, SEM, TEM, BET and FT-IR, and its adsorption behavior towards 1,2-DCA in water was studied. The results showed that amino groups substituted part of silicon hydroxyl groups, resulting in the rough pores, while slight change on the hexagonal stacking structure of NH2-MCM-41 occurred. After modification, the specific surface area, pore volume and pore diameter decreased by about 10%, 25% and 26%, respectively. The introduction of amino groups enhanced the affinity and adsorption capacity of NH2-MCM-41 toward 1,2-DCA, and the adsorption capacity increased from 11.75 mg·g−1 to 15.59 mg·g−1 with an increase rate of 32.68%.
The kinetic fitting showed that at the initial stage, NH2-MCM-41 adsorbing 1,2-DCA was controlled by physical adsorption, and it was mainly controlled by chemical adsorption during the subsequent process. The fitting of particle internal diffusion showed that the particle internal diffusion process was the main speed control step. Isothermal adsorption fitting showed that the adsorption sites of NH2-MCM-41 were evenly distributed, and monolayer and multilayer adsorption coexisted in the adsorption process. At 20 ℃ and pH 7, NH2-MCM-41 presented the best adsorption toward 1,2-DCA. Humic acid (HA) and coexisting anions inhibited the adsorption of 1,2-DCA on NH2-MCM-41. Thus, NH2-MCM-41 could effectively adsorb 1,2-DCA in water. The research results can provide a relevant reference for the treatment of polluted groundwater by chlorinated hydrocarbon.