Adsorption Of Uranium (Ⅵ) In Water By Chitosan Grafted Crown Ethers And Amidoximated Chitosan Grafted Polyacrylonitrile

Because of the severe situation of atmospheric pollution and the maturity thirst generation homebred nuclear power technology, large amount of nuclear power stations have been built. While these nuclear power stations provide clean energy for people and industry, more nuclear fuel is needed. This has made high requirements at the uranium mining and the production of nuclear fuel rod. It is extremely urgent that the prevention of uranium pollution, especially the treatment of uranium-containing waste water, must be studied. Among treatments of heavy metal ions in wastewater, adsorption is a low-cost, easy-operating and effective methods. As one of the natural polymers, there are lots of hydroxy and amino in chitosan. In the help of these active group, chitosan has excellent adsorption properties of some heavy metal ions. However chitosan could be dissolved in weak acid, and it has poor properties in mechanical strength and the selective adsorption of uranium, which have limited its application in the treatment of uranium-containing waste water.The grafting of crown ethers on chitosan might improve its insolubility and the selective adsorption of uranium. Amidoxime group has biocompatibility as well as chitosan, and it is well performed in the selective adsorption of uranium. Amidoximated chitosan-grafted polyacrylonitrile could promote the application of chitosan with well physical properties and selective adsorption of uranium.As one of multivariate statistical techniques, Response surface methodology (RSM) not only take the single factor in analysis, but also take the interaction of multifactors into account. Besides its statistical results could be used in the optimization of variables. The interaction and optimization are both neglected in the one factor design. RSM has been applied and admissive in all kinds of engineering.The Chitosan grafted crown ethers (CTCE) and amidoximated chitosan-grafted polyacrylonitrile (CTS-g-PAO) were prepared for the adsorption of uranium from water. The effects of pH, concentration of uranium and the solid-liquid ratio on the adsorption were optimized using response surface methodology (RSM). The adsorption capacity and removal efficiency of CTCE and CTS-g-PAO achieved234.26mg/g,79.92%and312.06mg/g and86.02%, respectively. The adsorption processes of both materials were better described by Langmuir isotherm and pseudo second order kinetic model. The materials and U(VI) ions formed a chelate complex due to FTIR spectral analysis. The surface morphology of CTCE and CTS-g-PAO was also investigated by SEM.CTS-g-PAO could be reused at least3times, and more than80%of the absorbed uranium could be desorbed by0.1mol/1HC1or EDTA-Na. CTS-g-PAO had better properties in selective adsorption of uranium than chitosan. Results obtained indicated that CTS-g-PAO was very promising in adsorption of uranium from water.