Preparation Of Graphene/Chitosan Based Composites And Study On Their Catalytic And Antibacterial Properties

Graphite oxide was synthesized by Hummers method with flake graphite as raw material.Silver nanoparticles was prepared by chemical reduction in the acetic acid solution of chitosan,and then silver(Ag)/graphene(rGO)/chitosan(CS)composite latex was prepared successfully through sol-gel method.The factors affecting the stability of Ag/rGO/CS latex such as concentration of chitosan,graphite oxide and AgNO3 were studied.The results indicated that Ag/rGO/CS latex can be prepared under such conditions as follow:the concentraion of acetic acid aqueous solution,chitosan acetic acid solution,graphite oxide and silver nitrate aqueous solution were 2.0wt%,3.5wt%,0.8wt%0.5 mol·L-1,respectively.The structural characterization of Ag/rGO/CS composite latex was characterized by TEM and XRD.The results positively evidenced that the silver nanoparticles are spherical or spheroidicity with mean diameter approximately at 10 to 25 nm in size,and the crystal shape of silver nanoparticles was face-centered cubic.Ag/rGO/CS microspheres were prepared by emulsion cross-linking method with Ag/rGO/CS latex as dispersed phase,liquid paraffin as continuous phase,and choosing different crosslinking agent.The factors affecting Ag/rGO/CS microspheres such as the type and concentraion of crosslinking agent,the concentraion of disperse phase and crosslinking temperature were studied.The results showed that Ag/rGO/CS nanoparticles microspheres can be prepared under such conditions as follow:the crosslinking temperature of vanilline is 60℃,the concentraion of Ag/rGO/CS colloidal sol,vanilline and glutaraldehyde were 8.06wt%,5.56wt%and 6.06wt%,respectively.The morphology of Ag/rGO/CS nanoparticles microspheres was characterized by SEM,which positively evidenced that the morphology of sample was spherical with mean diameters about 98 nm.The TEM photographs showed that silver nanoparticles are spherical with mean diameters about 10～25 nm.X-ray diffraction(XRD)pattern of the sample showed that chitosan is amorphous crystal while silver nanoparticles were face-centered cubic.Comparing with the FTIR absorption spectra,we can know that silver nanoparticles were embedded in Ag/rGO/CS microspheres.TGA showed that the introduction of silver nanoparticles significantly improve the decomposition temperature of rGO/CS microspheres.The antimicrobial ability of Ag/rGO/CS nanocomposite latex on Escherichia coli and Staphylococcus aureus were studied.The result showed that Ag/rGO/CS latex has more efficient antibacterial properties than single CS antibacterial agent.According to the structure and performance analysis of Ag/rGO/CS nanocomposite,the antimicrobial mechanism of Ag/rGO/CS nanocomposite material was speculated that the antibacterial property was the synergy between silver nanoparticles and rGO/CS composite.Using the catalytic reduction of 4-nitrophenol as the template reaction,catalytic performance of Ag/rGO/CS composite microspheres were analysized,and its reaction kinetics were discussed.