海藻酸钠的可控分子质量高效非均相降解

The highly efficient degradation of the controllable molecular weight of sodium alginate in a heterogeneous system

在多糖无法溶解的非均相体系中,研究海藻酸钠的高效降解工艺。以降解产物黏度为指标,单因素试验考察温度、催化剂用量和时间对降解产物黏度的影响,采用Box-Behnken法继续优化降解工艺。选择特定降解程度的海藻酸钠降解产物,使用凝胶色谱-示差-多角度激光光散射法测定分子质量,并进行红外光谱扫描和表面扫描电镜观察。海藻酸钠降解程度与温度、催化剂用量、时间在取值范围内正相关,在固液比1∶4(g∶mL)条件下,响应面优化所得最佳条件为温度61.53℃、催化剂用量1.0 g/10g海藻酸钠、时间5 h,所得降解产物数均分子质量为15.4 kDa。通过控制降解条件可相对精确地控制降解产物分子质量,获得数均分子质量在15 kDa~110 kDa内的降解产物。红外光谱扫描结果表明,降解处理对海藻酸钠糖链结构特征无影响,根据表面扫描电镜结果认为降解发生在多糖颗粒表面并逐渐深入。海藻酸钠的非均相降解方法具有效率高、操作简便、易于放大的优点,并可通过控制降解条件来获得特定分子质量的降解产物。

This study aimed to explore the degradation processing parameters of sodium alginate in a heterogeneous system.By measuring viscosity value,the effects of temperature,catalyst dosage and time in degradation process were investigated by the single-factor experiment and the Box-Behnken method.The degradation of products with different viscosity were selected and observed by FT-IR and SEM methods,and the molecular weight was determined by GPC-RI-MALS method.Within the parameter range,the degradation degree was positively correlated with the temperature,catalyst dosage and time.In the solid-liquid ratio of 1∶4(g∶mL),the optimal conditions were obtained as follows:The catalyst dosage of 1.0 g/10g sodium alginate at 61.53℃for 5 h.In this condition,the average molecular weight of the degradation product was 15.4 kDa.The molecular weight of the degradation products could be controlled by regulating the degradation parameters and a series of products with 15 kDa-110 kDa number-average molecular weight were obtained.The FT-IR results showed that the structure of the chain did not change after the degradation.The SEM photographs showed that the degradation occurred firstly on the surface of polysaccharide particles and then extended to the interior.The degradation of sodium alginate in the heterogeneous system had high efficiency and simplicity of operation was easy to magnify on the industrial scale.