超声波-微波协同H_2O_2降解壳聚糖的研究

Study on the degradation of chitosan by ultrasonic- microwave synergistic H_2O_2

采用正交实验方法优化超声波-微波联合H2O2氧化降解制备水溶性低分子量壳聚糖,并对水溶性低分子量壳聚糖进行红外光谱表征及热稳定性测定。正交实验结果显示,H2O2浓度8%,H2O2氧化10 min,超声-微波联合降解3 min,制备得到平均分子量为3.52 ku的低分子量壳聚糖。红外光谱分析表明壳聚糖在降解过程中分子骨架结构保持不变,引起了β(1→4)糖苷键部分断裂,降解过程伴随脱乙酰反应发生;差热分析表明降解后的低分子量水溶性壳聚糖的热稳定性低于原料壳聚糖。

The orthogonal experiment method was used to optimize the parameter of preparation of low molecular weight chitosan by hydrogen peroxide oxidation degradation combined with microwave and ultrasonic radiation degradation. The structure of low molecular weight chitosan was characterized by infrared spectroscopy and differential thermal analysis.The orthogonal experiment showed that the optimization parameters of preparation of low molecular weight chitosan were summarized as follows： the concentration of H2O2 was 8%,and the reaction time was 10 minutes combined with microwave and ultrasonic radiation degradation 3 minutes. The average molecular weight of product was 3.52 ku.Infrared spectrum analysis showed that the low molecular weight chitosan keeped the molecules skeleton structure and the β（ 1 → 4） glycosidic bond was fractured partly. The degree of deacetylation increased in the course of degradation. Thermogravimetric analysis showed that thermal stability of low molecular weight water- soluble chitosan was lower than that of raw materials chitosan.