Based On Functional Modification Of Hollow Mesoporous Silica Microspheres

A composite nanoparticle HMS/CTS-g-PAO was prepared via hollow mesoporous silica(HMS)obtained from sol-gel used as a skeleton material and chitosan(CTS)coated on HMS by inverse microemulsion synthesis used as matrix grafted polyacrylonitrile(PAN),which was transformed to polyamidoxime(PAO).The component and the structure of the HMS/CTS-g-PAO composite were examined by Fourier Transform Infrared Spectroscopy(FT-IR)and X-ray Diffraction(XRD).The morphology and the size of the HMS/CTS-g-PAO were confirmed by Scanning Electron Microscopy(SEM)and Laser Particle Size Analyzer.As potassium dichromate solution was used as chrome target for detecting the adsorption capacity of the prepared HMS/CTS-g-PAO.On the other hand,an active nano-catalyst with gold nanoparticles loaded in hollow mesoporous silica nanoparticles(HMSNs/Au)was prepared by one-pot sol-gel method.The characterization of HMSNs/Au composite were examined by SEM,XRD and N2 absorption-desorption isotherms(BET).Finally,the catalytic activity in reducing 4-nitrophenol or 2-nitrophenol of the composite are also studied.In this thesis,the main research results obtained are as follows:(1)The results show that the HMS/CTS-g-PAO was core-shell nanoparticles with the HMS as the core and the chitosan-graft-polyamidoxime(CTS-g-PAO)as the shell.the results indicate that the adsorption capacity of Cr(Ⅵ)was 3.28 mmol/g at the pH of the potassium dichromate solution was 2 and the concentration of the solution was 91.4 mg/L.Furthermore,the adsorption process was consistent with the pseudo-second-order kinetics and mainly belonged to chemical adsorption.(2)The adsorption mechanism of chromium on the HMS/CTS-g-PAO is described as:the Cr(Ⅵ)is electrostatically attracted by HMS/CTS-g-PAO and the reduction chromium Cr(Ⅲ)is chelated by the groups-NH2 and-C=N-OH in HMS/CTS-g-PAO.(3)One kind of composites involved in gold nanoparticles(AuNPs)loaded in HMS was prepared by one-pot sol-gel method,in which gold ions were loaded in hollow mesoporous silica spheres followed by sodium alginate reduction.Moreover,the preparation of HMSNs/Au involved in adsorption with smaller size have higher catalytic activity and no obvious damage on the chemical structure of HMSNs.(4)The high catalytic activity of HMSNs/Au denoted as apparent turn-over frequency(TOF)was detected by UV-vis spectrophotometer for the catalytic reduction of 4-nitrophenol(4-NP,74.5 h-1)and 2-nitrophenol(2-NP,108.7 h-1).