Preparation of Chitosan Graft Polyacrylic Acid/Graphite Oxide Composite and the Study of its Adsorption Properties of Cationic Dyes

Abstract

Chitosan-graft-polyacrylic acid/graphite oxide (CTS-g-PAA/GO) superabsorbent composite was prepared by solution intercalation graft copolymerization of chitosan (CTS), acrylic acid and graphite oxide (GO). The composite was characterized by Fourier transform infrared spectroscopy, powder X-ray diffraction, scanning electron microscopy, transmission electron microscope, thermogravimetric analysis and differential scanning calorimetry. Adsorption properties of cationic dyes such as rhodamine 6G (R6G) and methyl violet (MV) onto the composite were studied in detail. It was found that small amount of GO (0.02 g) can improve the adsorption capacities of dyes significantly. The interactions between GO and dye molecules are discussed. For R6G,there are both hydrogen bonds and the electrostatic interactions between CTS-g-PAA/GO composite and dye molecules, while for MV, there are only electrostatic interactions. The adsorption isotherms and kinetics were also studied. It was shown that adsorption of R6G was in accordance with the Langmuir isotherm equation, while that of MV met both the Langmuir and Freundlich equations. The adsorption kinetic of R6G and MV both were in accordance with the pseudo-second-order kinetic model.