Department of Chemistry, Faculty of Science, Universiti Brunei Darussalam, Jalan Tungku Link, Gadong, BE1410, Brunei Darussalam.
Department of Chemical Engineering, Faculty of Engineering, Universitas Indonesia, Kampus Baru UI, 16424, Depok, Indonesia.
Carbohydr Res. 2023 Dec;534:108971. doi: 10.1016/j.carres.2023.108971. Epub 2023 Oct 14.
This study presents a method for solvent-free mechanochemical synthesis of chitosan from chitin, sourced from the shells of mud crabs (Scylla serrata). The procedure involves a sequence of demineralization and deproteinization to extract chitin from the crab shells, followed by mechanochemical deacetylation. The chitin was deacetylated by grinding it as a solid blend with sodium hydroxide (NaOH) using a stainless steel mortar and pestle. After grinding, chitosan is isolated from the blend by repetitive washing and centrifugation. The chitosan product is then characterized using Fourier transform infrared spectroscopy, scanning electron microscopy, and X-ray diffraction analysis. These characterization techniques confirm the successful deacetylation of chitin to form chitosan. A high degree of deacetylation (DD) is achieved when the weight ratio of NaOH to chitin is 1:1 or higher, implying that the DD value can be enhanced by increasing this weight ratio. The mechanochemical reaction mechanism involves the hydroxyl groups on the NaOH particles reacting with the acetamide groups of the chitin strands, yielding solid chitosan and sodium acetate. This mechanochemical deacetylation approach is more practical than the conventional heterogeneous deacetylation in strong basic solutions, since it could suppress depolymerization of the resulting chitosan and requires significantly less base. This makes it a promising method for large-scale industrial applications.
本研究提出了一种从泥蟹（Scylla serrata）壳中提取的甲壳素为原料，通过无溶剂机械化学法合成壳聚糖的方法。该方法包括脱矿质和脱蛋白过程，从蟹壳中提取甲壳素，然后进行机械化学脱乙酰基。通过将甲壳素与氢氧化钠（NaOH）作为固体混合物进行研磨，用不锈钢研钵和杵进行机械化学脱乙酰基。研磨后，通过反复洗涤和离心从混合物中分离出壳聚糖。然后使用傅里叶变换红外光谱、扫描电子显微镜和 X 射线衍射分析对壳聚糖产物进行表征。这些表征技术证实了成功地将甲壳素脱乙酰基形成壳聚糖。当 NaOH 与甲壳素的重量比为 1:1 或更高时，可实现较高的脱乙酰度（DD），这意味着通过增加该重量比可以提高 DD 值。机械化学反应机制涉及 NaOH 颗粒上的羟基与甲壳素链上的乙酰胺基反应，生成固体壳聚糖和乙酸钠。与传统的强碱性溶液中的多相脱乙酰基相比，这种机械化学脱乙酰基方法更实用，因为它可以抑制所得壳聚糖的解聚，并且需要的碱量明显减少。这使其成为大规模工业应用的有前途的方法。
