Preparation Of Magnetic Composite Of Modified Chitosan And The Research Of Adsorption Property

Heavy metal pollution has become a worldwide problem due to its high toxicity and difficulty in treatment with the development of modern industry.The toxic effect of heavy metal in water body is affected by some factors—the type of its,physicomical properties,concentration,valance state and existence form.Chitosan is widely used in water treatment because of its environmental friendliness and reproducibility.Given the problems of chitosan—difficult separation,small specific surface area and limited adsorption activity sites as adsorbent in water treatment,polyethylenimine modified magnetic chitosan polymer composite(MCMC-PEI)was prepared through grafting polyethylenimine with a large amount of amino groups in the molecular chain onto chitosan in our research group.Graphite oxide@polyethylenimine modified magnetic chitosan polymer composite(GO@MCMC-PEI)and polyaniline@graphite oxide@polyethylenimine modified magnetic chitosan polymer composite(PANI@GO@MCMC-PEI)for removal of Cr(?)in aqueous solution were synthesized by further introducing graphite oxide with larger specific surface area and polyaniline with more active sites.The details are as follows:To figure out the disadvantages of chitosan of and limited adsorption activity sites as adsorbent,MCMC-PEI composite was prepared from chitosan,ferric trichloride and polyethyleneimine by modifying chitosan with polyethyleneimine and demonstrated reasonably by Fourier transform infrared spectrum(FT-IR),X-ray powder diffraction(XRD)and Vibrating Sample Magnetometer(VSM).The adsorption capacity of MCMC-PEI for Cr(?)of 100 mg/L is 110.63 mg/g as p H is five.The adsorption performance of the adsorbent is better when the temperature is lower,and the adsorption performance of composite for Cr(?)decreases with the increase of temperature.The adsorption equilibrium is basically reached when the adsorption time is 150 minutes.Furthermore,the adsorption progress could be well described by pseudo-second order model,Langmuir and Freundlich model.Thermodynamic studies(?G < 0,?H < 0)implied a spontaneous and exothermic process in nature.With the help of graphite oxide,large specific surface area and oxygen-containing functional groups on the surface and edge,can be modified and modified by covalent or non-covalent bonding,GO@MCMC-PEI adsorbent composed of polyethylenimine modified magnetic chitosan was prepared by covalent bonding of it and demonstrated by Fourier transform infrared spectrum(FTIR),X-ray powder diffraction(XRD)and Vibrating Sample Magnetometer(VSM).The adsorption capacity of GO@MCMC-PEI for Cr(?)of 100mg/L is 143.48 mg/g as p H is two.The adsorption performance of adsorbent for Cr(?)decreases with the increase of temperature.The adsorption equilibrium is basically reached when the contact time is90 minutes.Furthermore,the adsorption progress could be well described by pseudo-second order model and Langmuir model.Thermodynamic studies(?G < 0,?H < 0)implied a spontaneous and exothermic process in nature.Due to amino and imino functional groups of polyaniline can remove heavy mental by complexation,redox and ion exchange.Consequently,using graphite oxide@ polyethylenimine-modified carboxymethyl magnetic chitosan composite as raw material,PANI@GO@MCMC-PEI adsorbent was prepared through polyaniline modified raw material and demonstrated by Fourier transform infrared spectrum(FTIR),X-ray powder diffraction(XRD)and Vibrating Sample Magnetometer(VSM).The adsorption capacity of PANI@GO@MCMC-PEI for Cr(?)of 100 mg/L is 163.63mg/g as p H is five.The adsorption performance of adsorbent for Cr(?)decreases with the increase of temperature.The adsorption equilibrium is basically reached when the contact time is 120 minutes.Furthermore,the adsorption progress could be well described by pseudo-second order model and Langmuir model.Thermodynamic studies(?G < 0,?H < 0)implied a spontaneous and exothermic process in nature.