Synthesis Of A New Chitosan Derivative And Its Adsorption For Escherichia Coli

Chitosan is derived from deacetylation of chitin with many amino groups. Known to be biocompatible, non-toxic, biofunctional and biodegradable, it has been attractive for many fields. The cationic nature of chitosan make it adsorb negatively colloidal particles and bacterial in waste waters, but chitosan can dissolve in acid medium, which restricts its application, chemical modification is an common method to solve this problem and widen the application. In this study, a new chitosan derivative was synthesized by chitosan, ethyl cholorocarbonate was introduced to hydroxyl group of phthaloyl-chitosan through nucleophilic reaction, then hydrazine was added to give recovery of amino groups of chitosan and also give crosslinking to give network of this new derivative. The new chitosan derivative was characterized by FT-IR, 1H-NMR, XRD, DSC and TGA, respectively, the results indicate this new derivative has improved thermal stability and chemical stability compared to chitosan, and in bacterial adsorption studies, the bacteria adhere significantly and amounts of biofilm formed obviously. It is very attractive for adsorption in waste water treatment and studies about biofilm. The main composition of this paper is as follows:(1) Literature reviewIn this part, chitosan and chitin were introduced. Structure, physical and chemical properties of chitosan, chemical modification of chitosan and studies about it all over the world, application of chitosan and chitosan derivative in waste water treatment, and biofilm were presented.(2) Synthesis and characterization of the new chitosan derivativeThe new chitosan derivative was synthesized as follows: Firstly, the chitosan was protected by phthalic anhydride at 110 for 6h, then grafted by ethyl chlorocarbonate on hydroxyl groups of chitosan, and finally deprotected by hydrazine and also crosslinked by hydrazine, therefore, the amino groups appear again in the backbone of this new derivative with network structure. The new compound was characterized by FT-IR, 1H-NMR, XRD, DSC and TGA respectively. The new derivative only swells in acid medium and alkaline medium, the chemical and thermal stability of this new chitosan derivative has improved.(3) Bacterial adhesion studyIn order to study bacterial adsorption of the new chitosan derivative, chitosan derivative was formed film on glass or Polystyrene (PS) Petri dishes, dried in air at room temperature overnight, then washed by ultra pure water and methanol 3-5 times. The modified surface by chitosan derivative has presented good capability of bacteria adsorption and enhanced biofilm formation significantly, so it is interesting for adsorption in waste water treatment and biofilm studies.