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Synthesis of N-Alkyl-N,N-Dimethyl Quaternized Chitosan and its Application as Effective Absorbents towards Reactive Dye KN-R

Several types of N-alkyl-N,N-dimethyl quaternized chitosan (QC) derivatives with different alkyl chains were prepared as effective adsorbents towards reactive dye KN-R. QC with long dodecanyl chain was insoluble in neutral solution but could self-assembled into spherical nanoparticles. The effects of degree of quaternization and alkyl chain length on the adsorption properties of KN-R onto QC were investigated. The results showed that a higher degree of quaternization of copolymers led to a higher adsorption capacity. At similar degree of quaternization, QC nanoparticles with longer alkyl chains showed better adsorption ability than soluble free QC chain with shorter alkyl chains. Positive charges were accumulated on the surface of nanoparticles, which showed higher charge density than free polymer chain. The adsorption kinetics appeared to followed a well-described by pseudo-second-order model. Meanwhile, all of the obtained quaternized chitosan samples showed a higher adsorption capacity than the commercial adsorbent polyaluminium chloride. This work showed that adsorption ability of the cationic polymer could be improved by self-assembling into nanoparticles and that synthesized quaternized chitosan could be utilized as an efficient adsorbent for dye removal.