壳聚糖制备方法比较及其性能研究

Comparison of preparation methods and properties of chitosan

目的研究壳聚糖的制备方法。方法以甲壳素为原料,分别采用微波法和间歇碱液法制备壳聚糖,分析不同方法制备壳聚糖的粘均分子量、黏度、抗氧化性、吸湿保湿性能及表面形态的差异。结果微波法制备壳聚糖的最佳工艺条件为:氢氧化钠浓度为55%,料液比为1:15(g/mL),微波功率为400 W,时间20 min;间歇碱液法制备壳聚糖的最佳工艺条件为:氢氧化钠浓度为55%,料液比为1:20(g/mL),温度100℃,时间10 h,5 h更换碱液1次。2种方法相比,微波法反应时间短,碱液用量少,制备的壳聚糖粘均分子量和黏度较高,对羟基(·OH)自由基的清除效果好,吸湿性佳;间歇碱液法制备的壳聚糖脱乙酰度较高(88.95%),对1,1-二苯基2-三硝基苯肼(DPPH)自由基的清除效果较好,对原料的破碎化程度较高,但反应时间长,碱液用量多。结论从节能高效、绿色环保的角度考虑,微波法制备壳聚糖较理想。

Objective To investigate the preparation method of chitosan.Methods Chitin was used as raw material to prepare chitosan by microwave method and alkalinity batch process respectively.The differences of viscosity average molecular weight,viscosity,oxidation resistance,moisture absorption and moisture retention properties and surface morphology of chitosan prepared by different methods were analyzed.Results The optimum conditions for the preparation of chitosan by microwave were as follows:the concentration of sodium hydroxide was 55%,the solid-liquid ratio was 1:15(g/mL),the microwave power was 400 W,and the time was 20 min.The optimum conditions for preparing chitosan by alkalinity batch process were as follows:the concentration of sodium hydroxide was 55%,the ratio of material to liquid was 1:20 g/mL,the temperature was 100℃,the time was 10 h,and the alkali liquor was replaced once for 5 h.Compared with the two methods,the microwave method had shorter reaction time,less alkali dosage,higher viscosity average molecular weight and viscosity,better hydroxyl(·OH)scavenging effect and hygroscopicity.Chitosan prepared by alkalinity batch process had higher degree of deacetylation(88.95%),better 1,1-diphenyl 2-trinitrophenylhydrazine(DPPH)scavenging effect and higher degree of raw material fragmentation,but long reaction time and large dosage of lye.Conclusion From the point of view of energy saving,high efficiency and environmental protection,the microwave method is ideal to prepare chitosan.