Modification Of Chitosan And Starch Under Microwave Radiation And Their Application

In this thesis, with chitosan and starch as raw materials and under microwave radiation, chitosan-acrylamide graft copolymer,cationic starch and chitosan-cationic starch-acrylamide graft copolymer were synthesized and their flocculation performances in treating kaolin suspension and dyeing wastewater were tested. The main results are as follows:In the synthesis of chitosan-acrylamide graft copolymer with cerium ammonium nitrate as the initiator, the optimum conditions were determined as: microwave power 300 W, reaction temperature 50℃,reaction time 12min, initiator concentration 5mmol/L, monomer to chitosan mass ratio 3:1. Under optimum conditions the grafting ratio and grafting efficiency reached 128.4 % and 44.0 % respectively.In the preparation of cationic starch under microwave radiation with 3-chloro-2-hydroxypropyl trimethyl ammonium chloride (CHPTMA) as cationization agent and NaOH as catalyst, the optimum conditions were determined as: microwave power 400W, reaction time 6 min ,NaOH to starch mass ratio 0.07, CHPTMA to starch mass ratio 0.12, water to starch mass ratio 0.33, reaction temperature 80℃. Under optimum conditions the degree of substitution (DS) achieved 0.1326.In the synthesis of chitosan-cationic starch-acrylamide graft copolymer,the suitable reaction conditions were determined as: reaction temperature 40℃, reaction time 15 min, initiator concentration 5 mmol/L, monomer to chitosan and cationic starch mass ratio 4:1, cationic starch to chitosan mass ratio 3:1, microwave power 400 W.In the treatment of kaolin suspension by the three synthesized products, it was found that all three products have good flocculation performances and chitosan-cationic starch-acrylamide graft copolymer is the best.In dyeing wastewater flocculation experiments, it was found that when the amount of chitosan-acrylamide graft copolymer was 200 mg/L, the COD removal rate was 61.27 %; when the amount of the cationic starch was 250 mg/L, the COD removal rate was 58.45 %; and when the amount of the chitosan-cationic starch-acrylamide graft copolymer was 150 mg/L, the COD removal rate was 67.61 %.In addition, the structure and performance of the synthesized products were characterized by using FTIR, TG-DSC and SEM.