Acid catalyzed synthesis of ordered bifunctionalized mesoporous organosilicas with large pore

Abstract

Thiol-functionalized mesoporous ethane-silicas with large pore were synthesized by co-condensation of 1,2-bis(trimethoxysily)ethane (BTME) with 3-mercaptopropyltrimethoxysilane (MPTMS) using nonionic oligomeric polymer C 18H 37(OCH 2CH 2) 10OH (Brij-76) or poly(alkylene oxide) block copolymer (P123) as surfactant in acidic medium. The results of powder X-ray diffraction (XRD), nitrogen gas adsorption, and transmission electron microscopy (TEM) show that the resultant materials have well-ordered hexagonal mesoscopic structure with uniform pore size distributions. 29Si MAS NMR, 13C CP-MAS NMR, FT-IR, and UV Raman spectroscopies confirm the attachment of thiol functionalities in the mesoporous ethane-silicas. The maximum content of the attached thiol group (–SH) in the mesoporous framework is 2.48 mmol/g. The ordered mesoporous materials are efficient Hg 2+ adsorbents with almost every –SH site accessible to Hg 2+. In the presence of various kinds of heavy metal ions such as Hg 2+, Cd 2+, Zn 2+, Cu 2+, and Cr 3+, the materials synthesized using poly(alkylene oxide) block copolymer (Pluronic 123) as surfactant show almost similar affinity to Hg 2+, Cd 2+, and Cr 3+, while the materials synthesized using oligomeric polymer C 18H 37(OCH 2CH 2) 10OH (Brij-76) as surfactant exhibit high selectivity to Hg 2+.