Preparation And Application Of The Graft Copolymer Of Chitosan With Acrylamide

Chitin is abundantly present in nature and its amount is only inferior to cellulose. So how to avail of it is of great importance to human being. The derivative of chitin called chitosan is mainly produced by alkaline N-deacetylation of chitin. Chitosan is poly [ -(1,4)-2-amino-2-deoxy-D-glucopyranose]. At present, due to its high market price, chitosan can only be applied in paper making industry to some extent. Thus, recent years, modification carried out onto chitosan is the hotspot in this field to extend its application.In this paper, the following aspects were primarily studied, including: the preparation of chitosan from shrimp shells; the preparation of graft copolymer of chitosan with acrylamide (CAM); the application and the mechanism of modified chitosan.When isolating chitosan from shrimp, the reactions of descalcium, desprotein and deacetyl were systematically studied under different conditions. The structures of chitosan were characterized by infrared spectrum (IR).According to free radical theory, the CAM was synthesized with acrylamide and chitosan, through oxidation-reduction initiator systems in acetic acid aqueous solution. In order to obtain the optimum technological conditions, the dosage of 鈥?initiators, temperature of reaction, time of reaction and concentration of monomer were studied. The higher grafting rate (%) and the higher efficiency of grafting (%) were obtained when the dosage of potassium persulfate was 3 mmol/L, the dosage of sodium bisulfite was 1.5 mmol/L, temperature of reaction at 50 , time of reaction is 3 hours, the rate of w(Am)/w(Chitosan) is 8.The modified chitosan was applied in bleaching wheat pulp, deinking pulp, bleaching reed pulp and paperboard. The results showed that the modified chitosan has better potential to be used as dry strength for paper. For bleaching wheat pulp, the breaking length and burst index of paper were respectively increased by 910m and 29.6% when the modified chitosan dosage was 0.8%; the tear index of paper was increased by 26.5% when the dosage was 0.2%. For bleaching reed pulp, the breaking length of paper was increased by 23.9% when the dosage was 0.8%. For deinking pulp, the breaking length of paper was increased by 20.3% when the dosage was 0.6%. For paperboard, the ring crush index of paper was increased by 20.0%, the breaking length increased by 20.3%, burst index increased by 7.69%, elongation rate increased by 28.2% when the dosage was 0.4%. On the other hand,the modified chitosan was applied in disposal of wastewater. The result showed the modified chitosan has better flocculation potential to the white water (from Jinwan newspaper factory) and tripoli. In order to examine how to the effect factors including w (Am)/w (Chitosan), pH, time of sedimentation, and dosage influence its flocculation ability, the modified chitosan was applied in tripoli. When the modified chitosan was applied in disposal of white water, 98.9% turbidity and 75.8%COD can be decreased by 5mg/L dosage of the flocculant. And the mixture of 1mg/L the modified chitosan and 100mg/L PAC has as exactly the same flocculation potential as 5mg/L modified chitosan to white water.In this experiment, the mechanism of modified chitosan as strength agent is preliminarily studied. The result showed that the modified chitosan can improve fiber strength to some extent and can increase the bonding area.