Preparation And Application Of Multifunctional Silica Matrix Materials

Multifunctional composite materials based on silica gel have differentfunctional groups on the surface.They not only have silica gel properties such as strong mechanical strength,stable physicochemical properties and porous,but also possess strong adsorption capacity,easy separation,good biocompatibility and other excellent properties.Because of the different functional groups attached to silica gel surface,it is widely used in drug separation,biological conduction,environmental science and catalytic technology.Recently,with the development of more and more application prospects for multifunctional silica gels,to search for a fuanctional silica composite material with simple preparation,economical application,and high efficiency is a hot topic.Therefore,in this thesis we develop a series of multi-functional composite materials based on silica gel matrix,and application in heavy metal adsorption,catalytic science and drug separation research.First of all,a series of amino functionalized silica gels with different amounts of nitrogen atom ligands was prepared and characterized.Due to the coordination between nitrogen atom and some heavy metals,these amino-functionalized silica gels were systematically studied for removal of heavy metal ions such as Pb²⁺.Meanwhile,use these amino functionalized silica gels immobilized transition metal platinum(Pt)as calyststs for hydrosilylation of alkenes.By comparing their chelating ability with metals and catalytic properties,find out the best applicability of these series of amine functionalized silica gel.Second,because of electrical effect and steric hindrance of functional ligands,the complexing ability for metallic is difference.Here we prepared four functional silica gels by grafting different groups which contain sulphur,nitrogen or heterocyclic.Their structures also were chartered.And then compare their immobilized effects with metallic Pt and catalyst performance for hydrosilylation of alkenes.In this part,we also choose different functional silica used for adsorption and separation of Manganese ore,which from Yunnan province.The aim is to solve the difficult problem of metal purification and separation in Yunnan manganese ore.Third,due to bronic acid can form boronic acid metal salt complex with metals under the free condition,we chose boronic acid as a functional group we chose boronic acid as a functional group to modification silica gel.As a comparison,we used three different linkers to prepare different kinds of boronic acid functional silica.Then by immobilize Pt on this boronic acid functional silica to form heterogenneous catalysts.The structure of these catalysts were characterization by varies methods,and then used for hydrosilylation of alkenes.Through condition screening,we obtained a novel catalyst with high activity,selectivity and reusability.Forth,another important ability of boronic acid group is that it can react with compounds which have cis-glycol group,and this reaction is a reversible process.So in this part,we use boric acid functionalized silica gel to adsorb and purify glycoside V form crude extractive of siraitia grosvenorii,which is a Chinese traditional medicine.The result shows that boric acid functionalized silica has high-efficiency for separation glycoside V,and the purity of glycoside V can be improved about 40%.At the same time,after the silica gel combined with magnetic nanomaterials,they could be easily separated from solutions by magnetic separation,which is considered to be an effective and environmental benign separation approach,and the adsorption performance is invariable.Therefor magnetic silica gel nanoparticles are becoming more and more attention in analytical chemistry.So this part,magnetic materials is introduced on the basis of the silicon substrate to prepare magnetic silica gel nanoparticles,use five different functional groups,such as boronic acid,nitric acid,carboxyl,thiol and sulfonic acid,to modify the magnetic silica gel nanoparticles,and also used to immobilize metallic platinum and catalytic hydrosilylation reaction.By comparing there immobilized ability and catalytic efficiency,choose the boronic acid and thilo functional magnetic silica gel nanoparticles as the most suitable support matrix to immobilized metallic Pt.Finally,we found the strong effect of carboxyl group on platinum,so choosing EDTA as multi-carboxyl functional group to immobilized metallic Pt as a novel catalyst used in hydrosilylation of alkenes.The novel catalyst showed high catalytic activity,wide application,good repeatability and little waste discharged.