Search

Periodic mesoporous organosilicates (PMOs), containing bridging organic groups, such as phenylene- or ethylene-, and pendant groups such as imidazole- or thiol-, were synthesized by the hydrolysis and co-condensation of alkoxysilyl precursors, bis(triethoxysilyl)ethane (BTSE) or bis(triethoxysilyl)benzene (BTSB) under basic conditions. Cetyltrimethylammonium chloride was used to increase the porosity and surface areas of these materials via the surfactant template approach. Further functionalization was achieved by co-condensation with trialkoxyorganosilanes, including 3-mercaptopropyltrimethoxysilane or �-(3-triethoxysilylpropyl)-4,5- dihydroimidazole. Structural characterization of these materials was carried out by nitrogen gas sorption, X-ray diffraction, TEM, TGA, NMR, EDS and elemental analysis. The adsorption of phenolic compounds (phenol, 4-nitrophenol, 4-chlorophenol, 4- methylphenol, 2,4-dinitrophenol, 2,4-dichlorophenol, 2,4-dimethylphenol) and mercury (II) were investigated by batch testing. The material containing imidazole group exhibited a high affinity for 2,4-dinitrophenol. The capacities of the materials are: BTSE-IM (83.7 mg/g), BTSB-IM (53.8 mg/g) and MCM-IM (118.5 mg/g). The sorption of 24-DNP on BTSE-IM and BTSB-IM closely follow the Langmuir adsorption model. This means the sorption occurred on homogeneous surface as on a monolayer. The sorption of 24-DNP on MCM-IM, and 24-DCP, 24-DMP, 24-DNP on BTSE are more suitable to the Freundlich adsorption model. That means these sorptions are non-ideal and multi-layered on heterogeneous surface. The adsorption test for mercury (II) indicated that the materials containing -SH functional group showed better affinity for bonding mercury (II) than the materials containing the -IM group. These materials would be highly effective for removal of mercury (II).