Synthesis, Characterization And Application In Environment Of Bridged Periodic Mesoporous Organosilica

As a kind of technical means, which commonly used in the environmental monitoring area, HPLC has been requiring more accurate and more selective advantages with the rapid development of environmental science. Packing in the chromatography column is the essential part of HPLC and it plays a decisive role for improving the performance of HPLC. Bridged mesoporous materials, which have large surface area, relatively regular arrangement pore, narrow pore size distribution, high thermostability, mechanical stability and uniform organic groups in the skeleton, has a good application prospects as the chromatographic packing.Two kinds of bridged mesoporous materials that are phenylene group and amine group repectvely had been synthesized under the acid medium in this paper. Then they were characterized by a variety of physical and chemical methods with the aid of equipments. In addition, it was characterized though the HPLC using the different probe compounds.The spherical phenylene-bridged periodic mesoporous organosilica was synthesized with poly(ethylene oxide)-poly(propylene oxide)-poly(ethylene oxide) triblock copolymer (EO106PO70EO106, F127) and CTAB as template. XRD and TEM revealed that the material possess ordered mesoporous structure. FT-IR and NMR confirmed that the phenylene-bridged has been successfully introduced into the silica skeleton and the Si-C bond still be retaining after the synthesis and the template removal process. The carbon content of the material is 34%～39%. TGA indicates that the material was stable under 300℃. High specific surface areas (500～600 m2/g) and narrow pore size distributions (3.2～4.0 nm) have been revealed by the N2 sorption characterization. The material without further chemical modification was used as the stationary phase in reverse-phase HPLC, and compared with the commercial phenyl column that is grafted by phenyl-functional group on the surface of silica skeleton. The results showd that the bridged material from the experiments has a better separated selectivity for aromatic compounds than the commercial phenyl column and the residual silanol is significantly reduced.The periodic bridged amine-functionalized mesoporous organosilica was synthesized by the condensation of two kinds of bridged silicon precursor BTESE and BTMSPMA using poly(ethylene oxide)-poly(propylene oxide)-poly(ethylene oxide) triblock copolymer (EO20PO70EO20, P123) as template with the aid of NaCl and a co-solvent (ethanol). XRD and TEM studies revealed that the resultant BAFMOs materials possess mesocopically ordered structure. However, the order was decreased as the amount of BTMSPMA increased. N2 sorption showed that the surface area gradual decreased, from 970 m2/g to 795 m2/g, whereas the average pore size increased, from 3.7 nm to 5.4 nm as the amount of BTMSPMA increased. The organic functionalizations that include both the bridging ethylene group and the pendant aminopropyl group were successfully determined by FT-TR and NMR spectroscopy. NMR confirmed the retaining of the Si-C as well as the existing of the amino in the silica skeleton during both the solvent-extracted process and protonated process. Through elemental analysis, it is further confirmed the amino group intruding the material, which yields more than 50%; Thermogravimetric analysis explained the protonated process increased the material thermostability. Through the evaluation in reverse phase chromatography by Tanaka method, it can be found that the material has a promising application in the separation of isomeric molecules.