| In recent years, with the rapid development of nanotechnology, nano-structured materials have been widely used in many fields of analytical chemistry. Among them, the silver/silica nanocomposites received more attention due to its unique properties and broad application. Ag nanoparticles of metal nanoparticles had following advantages: high electric conductivity and thermal conductivity, good stability, the highest ideal dielectric constant. Silica had chemical inert, optical transparency and goog single dispersion. The chemical inert of silica protected the embedding material and did not affected redox reaction of metal nuclear surface besides shielding physically metal nuclear surface. At the same time, silica can provide surface of good biocompatibility and easy functionalization. So silica had good application prospect in the biological, chemical and medical science fieds and so on. But anion was difficult to contact with silica due to a large number of silicon hydroxyl which was negative charge in the surface of silica. This limited the application of silica nanoparticles. Research purpose of this thesis used the excellent characteristics of silica nanoparticles and conquered the shortcomings that can not determine anionic through incorporating functional polymer materials into silica nanoparticles. The chitosan had another function that is cross linking with silica. This was conductive to form silica mesoporous nanocomposites. This method broadened the application fields of silica nanoparticles.Two parts were included in this these:receive and research report. The first part was review, this part evaluated the characteristics of silica nanomaterials and introduced importantly synthesis method and analytical application progress research of nanocomposites of precious metals and silica. The second part was research report, we used two methods to prepare the Ag/SiO2/Chitosan nanocomposites and.researched the application of detecting small molecule anion.In the these, we used two different methods to synthesize Ag/SiO2/Chitosan nanocomposites and discussed the electrochemical luminescence application in luminol system. The works were included in the followings:1. The Synthesis of Ag/SiO2/Chitosan Nanocomposites and Its Analytical Application for Adsorbing Chromium (Ⅵ)We used the method of inverse microemulsion to dope chitosan which was a kind of natural polysaccharide and had positive charge and Ag nanoparticles which was catalyst of hexavalent chromium into trivalent chromium into silica, at the same time, we investigated the response for hexavalent chromium in modified electrode on the luminol system. The response of hexavalent chromium was relatively small if silica nanoparticles was doped with Ag nanoparticles only. Because the negatively charged silica nanoparticles prevented hexavalent chromium diffusing into its internal., silica nanocoposites doping only Ag nanoparticles can not adsorb hexavalent chromium due to no anion channel, that is, low efficiency of hexavalent chromium into trivalent chromium, thus the hypersensitivity of electrochemical luminescence was weak relatively. The response of silica nanocomposites for hexavalent chromium strengthened when we doped chitosan into silica nanocomposites. The effective composite of chitosan and silica nanoparticles formed the microchannel for the rapid diffusion of anionic in the shells and reaction with immobilized catalyst. This conquered the shortcomings that pure silica nanoparticles can not detect anion. Accordingly, we build a electrochemical luminescence method which had high selectivity, high sensitivity for detecting hexavalent chromium.2. The Method Study of Synthesising Ag/SiO2 Nanocomposites based on AgI doped SiO2 NanoparticlesWe synthesized AgI/SiO2 nanocomposites based on the reverse microemulsion method, then irradiating AgI precipitation with uv lamp to form Ag nanoparticles. This method reduced the leak of silver in the mesoporous silica, thus reducing the amount of Ag nanoparticles. TEOS hydrolyzed in nearly neutral environment in this reaction conditions, this reduced dissolution of AgI in stronger ammonia water and was helpful of forming silica mesoporous nanocomposites through doping chitosan. Accordingly, we provided a kind of new method of synthesizing silica nanocomposites doped Ag nanoparticles. |
PDF Full Text Request