Perparation And Application Of Modified Chitosan

In this thesis, new chitosan adsorbents were prepared by microwave heating.Studies were made into the absorption capacity for new chitosan adsorbents. Theconcrete contents were as follows:（1） The thiourea modification and ethylenediamine modification of chitosan wereprepared by microware heating, the best reaction condition of thiourea modifiedchitosan （TCTS） and ethylenediamine modified chitosan （CTSS） were choosing bysingle factor and orthogonal experiments; in the synthesis process homemade Fe₃O₄were added to get the magnetic thiourea modified chitosan （MTCTS） and magneticethylenediamine modified chitosan （MCTSS） respectively.The structure of productswere characterized by Fourier transform infrared spectroscopy （FT-IR）, X-raydiffraction （X-RD）, Scanning electron microscopy （SEM）.（2） The factors that might influent the absorption capacity of TCTS and CTSSwere investigated, such as pH value, absorbent dosage, adsorption time, initialconcentrations and temperature. It could be concluded that when operating conditionwere controlled at pH6.0, Cu²⁺initial concentration of100mg/L, the absorptioncapacity of TCTS and CTSS for Cu²⁺were85.53mg/g and131.1mg/g respectively;when operating condition were controlled at pH5.0, Pb²⁺initial concentration of100mg/L, the absorption capacity of TCTS and CTSS for Pb²⁺were79.26mg/g and103.3mg/g respectively.（3） TCTS and CTSS were eluted by Na₂-EDTA and NaOH mixed solution, theregeneration was studied. It was found that after the absorption of TCTS and CTSS forCu²⁺and Pb²⁺repeated5times, repeatable utilization of TCTS were86.11%and83.67%respectively, while repeatable utilization of CTSS were84.50%and81.92%respectively. The results showed that the regeneration of TCTS and CTSS were great.4) Using the homemade dynamic adsorption equipment, choosing the differentflow rate and column height, dynamic adsorption properties on TCTS for Cu²⁺were investigated. The results show that the flow rate faster, the column height lower,breakthrough time was shorter.（5） Testing the magnetism and adsorption properties for MTCTS and MCTSS, theresults show that, with the increase of Fe₃O₄dosage, magnetism of adsorbents wereincreased, and the adsorption capacity of MTCTS was increased, that of MCTSS wasdecreased. Thiourea modified chitosan with Fe₃O₄got more adsorptioncapacity.When the solution pH=6.0, Cu²⁺initial concentration was100mg/L,adsorption capacity of the MTCTS loaded0.1g Fe₃O₄and the MCTSS loaded0.01gFe₃O₄for Cu²⁺were93.54mg/g and127.8mg/g,respectively. Modified chitosan withFe₃O₄not only have nice adsorption preperties, but also magnetism which is helpful toseparate and recovery, which is practical on the real wastewater treatment.（6） Accoding to analysis of thermodynamics and kinetics on TCTS,CTSS andMTCTS, it was found that the adsorption on CTSS for Cu²⁺fitted Langmuir isothermalmodel, TCTS for Cu²⁺and Pb²⁺, CTSS for Pb²⁺, MTCTS for Cu²⁺fitted Freundlichisothermal model.These adsorption processes were spontaneous, endothermic andentropy minus.These adsorption also fitted Pseudo sceond kinetics model.（7） The results of the experiments on the TCTS and CTSS adsorption for binaryand ternary metal ions show that, in the binary ion solution, Cu²⁺was adsorbedpreferentially by TCTS and CTSS. the TCTS and CTSS are preferred adsorption Cu²⁺;CTSS was suited for separating the Cu²⁺-Pb²⁺-Zn²⁺and Cu²⁺-Pb²⁺-Cd²⁺ternary metalions solutions, and TCTS was suited for separating the Cu²⁺-Cd²⁺-Ni²⁺ternary metalions solution. TCTS and CTSS has good adsorption selectivity.