Modification And Performance Testing Of Mesoporous Silica

Mesoporous silica materials attract widespread attention in chemical, environmental,novel material-design fields, due to their high specific surface area, large pore volume,uniform and controllable pores. However, pure siliceous materials are lack of active sites,so further modification is generally needed when mesoporous silica is applied in realindustry process. Normally, physical or chemical properties of the mesoporous silica canbe effectively improved by methods of in-situ modification, post treatment, solid grindingor the adaption of new synthetic strategies. Based on these, Al species were introduced intothe mesoporous silica by a solid grinding method, then a series of Al-containingsilica-carbon composites were synthesized via a sol-gel strategy, and biological templateswere used as bio-template to fabricate novel mesoporous siliceous materials.Firstly, we used the simple and facile solid-grinding strategy to synthesizeAl-containing SBA-15materials (GAx). Different amounts of Al species were introducedinto the structure of mesoporous SiO2by controlling the Al/Si molar ratio (rAl/Si) of thereaction precursors. The aluminum species are highly dispersed in SBA-15as frameworkforms. As a result, the highly ordered mesoporous structure of traditional SBA-15waspreserved. Compared with traditional SBA-15, those solid-grinded GAx materials havedramatically improved in adsorption capacities. Importantly, the solid-grinded samplesalso have better structural and adsorption property than the impregnated Al-SBA-15sample.Subsequently, the hierarchical porous SiO2/EG composites were synthesized byhydrolysis and condensation of siliceous precursors (TEOS) into the pore and surface ofexpanded-graphite (EG). The SiO2/EG composites retain the advantages of mesoporoussilica and EG. Consequently, the porous SiO2/EG composites present the good adsorptioncapacity to organic dye (methylene blue).Furthermore, we used camellia petals as template to synthesize hierarchicalmesoporous silica. TEOS was firstly hydrolyzed on the surface and/or cell walls of thecamellia petals. Porous SiO2materials were obtained with the process of drying in air andcalcination to remove the template. The synthesized porous siliceous materials have thelayer morphology, well-replicated hierarchical pore structure of petals, and rather strongeradsorption capacity than conventional SBA-15.Finally, we used P123as the soft template, cotton as hard template to manufacture mesoporous silica PC-x-Y materials. The cell parameters of samples can be adjusted bychanging the mass ratio of cotton to SiO2or the hydrothermal aging temperature. All thecotton co-templated PC-x-Y samples have short “axis” morphologies and many openpores, which make those samples display higher MB adsorption capacities than SBA-15.