The Research On Chitosan Crosslinking Or Grafting Modification And Performance

In this paper,we made a systematic research on the chitosan grafting or cross-linking modification , including cross-linking of chitosan with trimethyl ammonium,introducing chelate agent into chitosan,grafting copolymer on chitosan etc. The adsorption properties and the scale inhibitive performance of the chemical modified chitosan were also investigated.A kind of new modified chitosan absorbent was synthesized with chitosan (CTS), acrylamide(AM) and methacryloyloxyethyl trimethyl ammonium chloride(DMC) as raw materials.The structure of product was confirmed by FTIR, SEM and XRD.The reaction condition was optimized through the orthogonal experiment. The adsorption behavior to Cu²⁺,Zn²⁺,Cd²⁺ was confirmed to obey the Langmuir equation.Because of its good selective adsorption ability of Cu²⁺ and Zn²⁺ in the Cu²⁺-Zn²⁺-Cd²⁺ ternary system,the absorbent has latent application prospect in the aspects of separation, extraction, enrichment and recovery of Cu²⁺ and Zn²⁺.The results of the simulated treatment of printing waste water indicated that CAD had a strong adsorption ability to Direct Fast Blue GL under weak acid conditions, and the removing rate increased with increasing the CAD mass concentration.A novel crosslinked chitosan absorbent CCTS was synthesized,which is more efficient than chitosan and could be reused.The structure of CCTS and intermediate products were characterized by IR, XRD, SEM and element analysis.Adsorption kinetics have been tested and fitted to adsorption model. The adsorption behavior of CCTS to Pb²⁺,Cu²⁺,Cd²⁺,Ni²⁺ was well fitted to the pseudo-second-order equation. The data were analyzed by the Langmuir and Freundlich model, showing that best fit was obtained with the Langmuir equation.The thermodynamic investigation of adsorptions shows that adsorption of CCTS to Pb²⁺,Cu²⁺,Cd²⁺,Ni²⁺ is spontaneous.Because the values of Gibbs free energy (â–³adsG) are negative and the calculated entropy values (â–³adsS) of interactions are positive.However the positive values of the variation in enthalpy (â–³adsH) show that besides chemisorption, other processes of decalescence, such as physical adsorption and swelling of CCTS were also involved.The adsorption ability of CCTS to metal ions in binary or ternary solutions composed of Cu²⁺, Ni²⁺, and Cd²⁺ was researched. The results show that no selective adsorption ability of CCTS to Cu²⁺,Ni²⁺ and Cd²⁺.The recycling investigation shows that CCTS can be used to remove metal ions repeatedly.Synthesis and adsorption properties of calix[6]arene derivatives modified chitosan. Comparing with calix[4]arene, calix[6]arene has the bigger adjustment space, thus stronger selective adsorption ability to big metallic ion was shown. The calix[6]arene-chitosan polymer was synthesized by the reaction of mono-substituted calix[6]arene derivative with pretreated chitosan. The absorption properties of polymer towards Mn²⁺ ,Pb²⁺ ,Cr³⁺ and Cu²⁺ were studied.The scale inhibitive performance of modified chitosan was studied. Scale inhibitive performance was evaluated by determining scale inhibitive rate using static anti-scaling method.Through the test of scale inhibitive performance of maleic anhydride, acrylic acid or acrylamide modified chitosan, the effect of the scale inhibitor amount, Ca²⁺ concentration, and pH value to scaling inhibition rate was investigated. Therefore, the superior scale inhibitor can be obtained.