Quaternary Ammonium Salt Of Chitosan And Its Applied Research In Water Treatment

The modified chitosan flocculant was made by graft of chitosan and dimethyldiallylammonium chloride (DMDAAC) using the ammonium persulfate as initiator. The impact of experimental conditions (the dose of initiator, reaction temperature,reaction time and the mass ration of chitosan and DMDAAC) on efficiency of reaction was investigated by orthogonal experimental method and the optimal conditions were obtained: the dose of initiator was 0.05%, reaction temperature was 30℃, reaction time needed 8 h, and the mass ration of chitosan and DMDAAC was 1:9. IR spectrometry and ~1H-NMR indicated that the quaternary amonium salt drivatives of chitosan formed by co-polymerization of chitosan and DMDAAC. The solubility of quaternary ammonium salt of chitosan was much higher than chitosan and could reach 62 g/L at 65℃.The effects of pH value, quaternary ammonium salt of chitosan dosage and stiring time on COD removal rate of municipal Wastewater were investigated to obtain the optimal experimental conditions, i.e., pH value range of Wastewater: 8-12, and dosage of chitosan quaternary ammonium salt: 90.9-130.4 mg/L. Under the optimal conditions the COD removal rate of Wastewater can be over 80%. The efficiencies of turbidity removal of quaternary ammonium salt of chitosan flocculant used to treat the test water of kaolinite were also studied. The results of residual turbidity and ζ potential indicated that the optimal dosage of the modified chitosan flocculant totreat the test water of kaolinite was 5-8 mg/L. The new modified chitosan flocculant will not only improve the COD and turbidity removal rate but also avoid secondary pollution, with better environment protection effect available.