Adsorption Characteristics Of Heavy Metal In Groundwater Adsorbed By Modified Chitosan

In China, shallow groundwater has polluted by heavy metal due to human activites. In situ groundwater remediation has been paid on attention by government and scientists. In this paper, the static and dynamic adsorption properties of heavy metal such as Zn2+, Cr6+ in groundwater was studied by cross-linked chitosan materials which were cross linked with PEG400.The result showed that under CTS: PEG=1:2, 0.1% Zn ion inprinted, the removal efficiency of Zn2+ was the highest;under CTS: PEG=1:1,1.6% Cr ion imprinted, the removal efficiency of Cr6+ was the highest.The study of infrared spectroscopy showed : Heavy metals Zn2+, Cr6+ reacted with cross-linked chitosan in different groups. The reaction between Zn2+ and PEG-CTS occurred mainly in–NH2, -OH, -O-C-O-. The reaction between Cr6+ and PEG-CTS occurred mainly in-CONH- and -O-C-O-.The study of static non-equilibrium adsorption isotherm showed: 1) PEG-CTS inprinted Zn2+ was close to the adsorption saturation after 20 h. 2) PEG-CTS inprinted Cr6+ followed a rapid adsorption to the adsorbent in 0.5 h and it was close to the adsorption saturation after 4 h. The adsorption of Cr6+ was a bit faster than the one of Zn2+.The study of static non-equilibrium adsorption isotherm showed: the adsorption of Zn2+, Cr6+ on PEG-CTS both were according to Langmuir adsorption isotherm model. Under temperature 20℃and pH=7 conditions, the maximum adsorption capacity of bivalent zinc ion reached 18.2 mg per gram. The maximum adsorption capacity of chromium ion reached 14.8 mg per gram.The study of material re-using showed: the adsorption capacity of Zn2+ , Cr6+ decreased by 15% and 6% after four times using.The study of dynamic adsorption showed: 1) For continuous input mode, the time of heavy metals seeping from the sand column is longer than the one of NaCl because of the adsorption effect. 2) The maximum adsorption capacity of zinc drops to 0.895 mg per gram, reducing by 5% of static maximum. The maximum adsorption capacity of zinc drops to 6.5 mg per gram, reducing by 44% of static maximum.