Study On Preparation And Properties Of Chitosan Resin Crosslinked By Formaldehyde And Epichlorohydrin

Our aim is to develop a novel type crosslinked chitosan resin (AECTS) withgood properties in this paper.With chitosan as the raw material, a new type chitosan resin was prepared through inverse suspension crosslinking by formaldehyde and epichlorohydrin. The effect of the operating conditions on the properties of the resin was investigated. The structure of the resin was characterized by FTIR, WXRD and TGA. The results revealed that the dosage of formaldehyde, epichlorohydrin and emulsifier, the stirring speed, the chitosan concentration and the treatment conditions with hydrochloric acid affected the properties of the resin largely. A strong-acid-resistance, high-capacity, good-strength, large-porosity chitosan resin was obtained under the optimum reaction conditions. The crystalline grade of crosslinked chitosan reduced and the thermal stability decreased.The complex of AECTS with Cu2+, Ni2+, Co2+ were systhesized and characterized by FTIR, WXRD, TGA and DSC. The results of those analysis showed that the adsorption was realized through binding -NH2 and -OH groups in AECTS with ions. Compared with AECTS, the structure and properties of AECTS-Cu, AECTS-Ni and AECTS-Co had changed. The crystalline grade reduced; The water content increased; The combination firmness degree of water decreased; The thermal stability reduced, and the decomposition residue improved remarkably. In this paper the adsorption mechanism of AECTS with Cu2+, Ni2+ and Co2+, the transformation reason of material performance before and after adsorbing, the chemical environment of ions in AECTS and so on were deeply analysized and discussed.The adsorption thermodynamics properties of AECTS with Cu2+, Ni2+ and Co2+ and the influence of different media on adsorption were studied. The results showed that AECTS adsorbed Cu2+ and Ni2+ mainly by complexation, the experimental data fit well into the Langmuir adsorption isotherm and the process obeyed the formationof monolayer adsorption. AECTS adsorbed Co2+ mainly by complexation and physical style, the experimental data fit well into the Langmuir and Freundlich adsorption isotherm at the same time. The effect order of media was HCl>CdCl2>MgCl2>NaCl, and their effect mechanism differed greatly.The adsorption isotherms of benzoic acid from water onto the novel resin had been determined at different temperatures and the thermodynamic parameters in adsorption process had been calculated. The experimental results fit with Freundlich equations well. The thermodynamics of the systems related closely to the adsorption mechanisms. When the concentration of benzoic acid was low, the adsorption was an exothermal process with the system's entropy decreasing, and the decrease of temperature did benefit to the process. When the concentration of benzoic acid was high, the adsorption was an endothermal process with the system's entropy increasing, and the increase of temperature did benefit to the process.