Preparation of mesoporous silica with grafted chelating agents for uptake of metal ions

Functionalized hexagonal mesoporous silicas were prepared by chemical modifcation of a surfactant free mesoporous silica (OSU-6-W) with 3-glycidoxypropyltrimethoxysilane. Different degrees of derivitization with 3-glycidoxypropyl were realized by using either a single silylation reaction or two silylation reactions with an intermediate hydrolysis step. The two resulting inorganic–organic hybrids were characterized by solid-state 29Si nuclear magnetic resonance (NMR) spectroscopy, a titration method, and elemental analysis of the modified samples and the average numbers of pendant groups were found to be 2.17 and 3.49 groups/nm2, respectively. Surface area analysis showed that these materials have pore diameters of 40.7 and 33.2 Å and surface areas of 966 and 720 m2/g, respectively. Infrared spectroscopy, solid-state NMR for 13C and 29Si nuclei and X-ray diffraction patterns are in agreement with the success of the preparation of organically modified mesoporous silicas. The basic centers of the attached pendant groups provide the capacity to extract copper from aqueous solution via an adsorption process that followed the Langmuir model and had a remarkably high capacity of 6.75 mmol g−1 for adsorption of copper.