Preparation And Adsorbtion Property Of Graphene Modified By Quaternary Ammonium Chitosan

With a chemical stability and large specific surface area, graphene can be applied as an adsorbent in treatment of wastewater. Water-soluble cationic quaternary chitosan(HACC) can absorb pollutants in wastewater through the electrostatic interaction. Combining the advantages of both graphene and HACC, graphene was modified by HACC, which is expected to improve the dispersion stability of graphene in solvents and confer the better adsorption property of graphene in this work.In order to improve the dispersion stability of graphene in solvents, 2-hydroxypropyltrimethyl ammonium chloride chitosan(HACC)-modified graphene composites(HACC-RGO) were prepared through the non-covalent electrostatic interaction between HACC and graphene oxide firstly and then the reduction by hydrazine. The structure and morphology of HACC-RGO were characterized by Fourier transform infrared spectroscopy, X-ray diffraction and scanning electronic microscopy. These results showed that HACC were introduced successfully onto the graphene surface and inserted into the layers of graphene. TG test showed that the content of modifier HACC in HACC-RGO increased with the increasing amount of HACC. The Zeta potential value of HACC-RGO increased and the particle size decreased with increasing amount of HACC. After modified by HACC, HACC-RGO could be dispersed well in aqueous solutions, and exhibited a good dispersion stability at the pH range from 2 to 9. The electrochemical properties of HACC-RGO were investigated by cyclic voltammetry. HACC-RGO had a good electrical conductivity.The adsorption property of HACC-RGO powder for methyl orange was studied by UV-Vis spectrophotometry. The adsorption condition and kinetics were discussed in details. The results showed that the adsorption ratio of methyl orange of HACC-RGO was much higher than those of graphene and HACC.The adsorption system of HACC-RGO reached saturated extent after 8h. The removal for methyl orange increased with increasing adsorption temperature. The adsorption kinetics was in line with the pseudo-second-order kinetic adsorption model, indicating that the particle surface diffusion was the rate-limiting step. The isotherm data were well described by the Freundlich isotherm model, indicating that the adsorption process was a physical adsorption.HACC-RGO/CS spheres were prepared by the microfluidics method. The structure and morphology of HACC-RGO/CS spheres were characterized by X-ray diffraction, 3D microscopy, thermo-gravimetric analysis and scanning electronic microscopy.HACC-RGO/CS spheres were spherical and contained HACC-RGO, which was close to the theoretical value.The adsorption of HACC-RGO/CS spheres for methyl orange were studied and compared with CS spheres. The adsorption ratio of HACC-RGO/CS spheres for methyl orange was 91.89%, and the desorption were 11.32% and 87% respectively in H2 O and 2wt %NaOH solution.