巯基修饰MCM-41分子筛的制备及其对Cr(Ⅵ)的吸附动力学

Synthesis of SH-MCM-41 and its adsorption kinetics to Cr( Ⅵ)

以微硅粉为硅源,CTAB和PEG-6000为模板剂,制备得到MCM-41介孔分子筛,采用后接枝法将巯丙基三甲氧基硅烷引入到MCM-41的表面和孔道内,合成了巯基功能化的MCM-41介孔分子筛(SH-MCM-41)。采用TEM、N2吸附-脱附曲线、TG分析和XPS对样品进行了表征。以巯基功能化的样品为吸附剂,对含Cr(VI)的溶液进行了静态吸附实验,探讨了吸附过程的动力学。结果表明,SH-MCM-41对水中Cr(Ⅵ)的吸附经240 min可基本达到平衡,其理论吸附量为21.3 mg/g;利用准一级、准二级、Elovich方程、粒内扩散模型和班厄姆孔道扩散模型对吸附过程进行模拟,模拟结果表明,吸附过程符合准二级动力学模型,其拟合度R2为0.991,Elovich方程模拟相关系数R2大于0.95,表明吸附过程包含了多种反应机制。结果显示,吸附过程由液膜扩散、颗粒扩散和孔道扩散共同控制。

The MCM-41 mesoporous sieves were successfully synthesized using the silica fume as silica source,CTAB and PEG-6000 as template agent. 3-Mercaptopropyl trimethoxysilane was directly introduced into MCM-41 by post-synthesis modification. The SH-MCM-41 was characterized by TEM,N2adsorption-desorption,TG / DTA and XPS. Using the SH-MCM-41 mesoporous sieves as adsorbent,static adsorption experiments were carried out to investigate the adsorption performance of Cr( Ⅵ) in water solution and to determinate the kinetics of the adsorption process. The results demonstrated that the adsorption reached equilibrium after 240 min. The maximum adsorption capacity was 21. 3 mg / g. The adsorption process was simulated with five models. The results showed that the adsorption kinetics was more appropriate for the pseudo-second-order equation,and the degree of fitting( r-squared) was 0. 991. The r-squared in Elovich equation was greater than 0. 95,indicating that the adsorption process included several reaction mechanisms. The results showed that the adsorption process was controlled by film diffusion,particle diffusion and pore diffusion.