可及度对甲壳素脱乙酰效率的影响初探

Preliminary Study on the Effect of Accessibility on the Deacetylation Efficiency of Chitin

摘要: 甲壳素的分子内与分子间氢键相互作用使甲壳素形成微纤维网状的高度结晶有序结构，导致甲壳素本身难脱乙酰。本文以NaOH/尿素混合溶液作为溶剂低温下溶解甲壳素，再将其沉淀，改变其凝聚态结构，然后进行脱乙酰反应。研究了NaOH/urea配比对甲壳素溶解度及NaOH浓度对脱乙酰反应的影响，采用FTIR、SEM、XRD、TG表征分析了溶解–沉淀过程处理后甲壳素的结构性能。结果表明，NaOH/urea = 12/6(w/w)混合溶液的溶解效果最佳，溶解度可达90%。溶解–沉淀处理后的甲壳素原有的微纤维状有序结构被破坏，呈无定形态且乙酰胺基可及度变大。NaOH浓度降低至50 wt%时即会起到用60 wt%处理甲壳素原粉同样的脱乙酰度，制得壳聚糖。

Abstract: The intramolecular and intermolecular hydrogen bond interaction of chitin makes chitin form a highly crystalline ordered structure of microfibrils, which makes chitin itself difficult to dissolve and difficult to deacetylate. In this paper, the NaOH/urea mixed solution was used to dissolve chitin at low temperature, and then it was precipitated to change its condensed structure, and then deacetylation reaction was carried out. The effects of NaOH/urea weight ratio on the solubility of chitin and NaOH concentration on deacetylation were studied. The structural properties of chitin after dissolution-precipitation treatment were analyzed by FTIR, SEM, XRD and TG. The results show that the NaOH/urea = 12/6(w/w) mixed solution has the best dissolution effect and the solu-bility is 90%. The original microfibrous ordered structure of chitin after dissolution-precipitation treatment is destroyed, and it has an amorphous state and the accessibility of acetylamine group becomes large. When the NaOH concentration is lowered to 50 wt%, the same degree of deacetyla-tion with 60 wt% of the chitin raw powder is obtained.