Direct Synthesis of Cubic Benzene-Bridged Mesoporous Organosilica Functionalized with Mercaptopropyl Groups as an Effective Adsorbent for Mercury and Silver Ions

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• 作者：Hao-Yiang Wu ; Ching-Ting Chen ; I-Ming Hung ; Chia-Hsiu Liao ; Shanmugam Vetrivel ; Hsien-Ming Kao
• 刊名：Journal of Physical Chemistry C
• 出版年：2010
• 出版时间：April 22, 2010
• 年：2010
• 卷：114
• 期：15
• 页码：7021-7029
• 全文大小：502K
• 年卷期：v.114,no.15(April 22, 2010)
• ISSN：1932-7455

文摘

Well-ordered cubic (Pmn symmetry) benzene-bridged periodic mesoporous organosilicas (PMOs) functionalized with variable contents of thiol groups were successfully synthesized via a one-step co-condensation of 1,4-bis(triethoxysilyl)benzene (BTEB) and 3-mercaptopropyltrimethoxysilane (MPTMS) in a highly acidic medium with use of cetyltrimethylammonium bromide (CTMABr) as the structure-directing agent. The materials thus obtained exhibited ordered and uniformed mesopores up to 25 mol % of MPTMS in the initial mixture. Direct evidence of the simultaneous presence of chemically attached thiol and benzene moieties was provided by solid-state ²⁹Si and ¹³C NMR spectroscopy. The present cubic PMOs can be synthesized with a wide temperature window from 0 to 100 °C without any undesirable phase transformation. On the contrary, this is not possible when BTEB was replaced by tetraethoxysilane (TEOS) as the silicon source for the conventional synthesis of SBA-1 with Pmn symmetry. It suggests that the benzene-linking spacer of BTEB has a beneficial effect on the enlargement of effective head group of the surfactant against the temperature changes and thus prevents phase transformation to a hexagonal mesophase. These thiol-functionalized benzene−silica materials exhibited high adsorption affinity toward metal ions such as Hg²⁺ and Ag⁺, but not for Cd²⁺, Co²⁺, and Pb²⁺. Of particular interest is that the ¹³C NMR chemical shift of the carbon atom adjacent to the −SH group is sensitive to the Hg²⁺ and Ag⁺ ion bindings, shifting from 27 ppm to 37 and 34 ppm, respectively. Such a significant NMR shift provides clear evidence that there are strong interactions between the thiol groups and the Hg²⁺ and Ag⁺ ions.