低成本制备MCM-41介孔分子筛及其对镉离子的吸附性能（英文）

Synthesis and Characterization of MCM-41 Mesoporous Materials from Silica Fume for Cadmium Adsorption

以廉价的硅铁行业的废弃物微硅粉为硅源,十六烷基三甲基溴化铵(CTAB)为模板剂,采用碱法提纯-水热法合成制备了纯硅的MCM-41介孔分子筛。用红外光谱(FTIR)、小角X射线衍射、液氮吸附脱附、场发射扫描电子显微镜和高分辨透射电子显微镜对分子筛进行了结构表征和表面积及孔径分析。结果表明:所制备的分子筛的比表面积是918 m2/g,孔容1.11 cm3/g和孔径2.9 nm。采用静态吸附方法,研究了所合成的分子筛对水溶液中Cd2+离子的吸附行为,分析了pH值、分子筛质量、吸附时间和Cd2+的初始浓度对吸附的影响,并探讨了该吸附剂对Cd2+的吸附热力学和动力学特性。结果表明:当溶液的pH值为2.0～7.0,吸附剂的量在30～130 mg范围内时,吸附率随着pH值和吸附剂用量的增加而增加,当吸附剂用量为130 mg时,有序介孔分子筛对Cd2+离子的去除率基本稳定。有序介孔分子筛对Cd2+离子的吸附量随吸附时间的增加而增加,在120 min时达到吸附平衡。有序介孔分子筛对Cd2+的等温吸附过程更符合Freundlich模型,吸附动力学较符合准二级吸附方程。

This study reports a facile synthetic method to produce MCM-41 mesoporous materials using silica fume and cetyltrimethylammonium bromide(CTAB) as a silicon source and structure-directing agent, respectively. The materials were characterized by different techniques such as Fourier-transform infrared spectroscopy, X-ray diffraction, scanning electron microscopy(SEM), transmission electron microscopy(TEM) and N2 adsorption-desorption. It was confirmed that the as-synthesized material exhibited a well-ordered mesostructure with a high surface area of approx. 918 m2/g, large pore volume of 1.11 cm3/g, and average pore diameter of 2.9 nm. The adsorption property of MCM-41 was evaluated by the removal of Cd2+ ion from water. The effects of pH, the amount of molecular sieves, the contact time, and initial Cd2+ concentration were investigated. The results show that when the pH of the solution is 2.0-7.0 and the amount of adsorbent is in the range of 30-130 mg, the adsorption rate increases with the increase of pH value and amount of adsorbent. When the amount of adsorbent is 130 mg, the removal rate of Cd2+ ions by ordered mesoporous molecular sieves is basically stable. The adsorption amount of Cd2+ Ions by ordered mesoporous molecular sieves increased with the increase of adsorption time, and reached the adsorption equilibrium at 120 min. The adsorption of Cd2+ by MCM-41 corresponded with the pseudo-second-order kinetic equation, and the isothermal adsorption of Cd2+ followed the Freundlich model.