Department of Chemical Engineering, Institute of Chemical Technology, Matunga, Mumbai-19, India.
Department of Chemical Engineering, Institute of Chemical Technology, Matunga, Mumbai-19, India.
Carbohydr Polym. 2020 Feb 15;230:115600. doi: 10.1016/j.carbpol.2019.115600. Epub 2019 Nov 11.
Kinetics of chitosan depolymerization were studied in dilute acetic acid solution, in presence of H-Mordenite (H-MOR). Rate constants for chitosan depolymerization were determined by measurement of molecular weight, using Gel permeation Chromatography (GPC). Depolymerization rate of chitosan was altered in presence of an acidic, porous material like H-MOR. Maximum concentration of H-MOR studied during process led to minimal increase in energy of activation, from 20.54 kJ/moL to 23.25 kJ/moL. Infra-red spectroscopy, adsorption studies and rheological assessment indicated adsorption /grafting of chitosan onto porous H-MOR surface as the possible mechanism for facilitation of the depolymerization process. Under extreme conditions investigated during process optimization, H-MOR resulted in a three-fold reduction in 5-Hydroxy Methyl Furfural (5-HMF) formation and over ten times decrease in glucosamine content, as compared to reactions conducted without H-MOR. Therefore, presence of H-MOR is imperative to cleave chitosan in controlled manner and obtain products of desired molecular weight, with fewer impurities.
壳聚糖在稀醋酸溶液中，在 H-Mordenite（H-MOR）存在下的解聚动力学进行了研究。通过使用凝胶渗透色谱（GPC）测量分子量来确定壳聚糖解聚的速率常数。在酸性多孔材料如 H-MOR 的存在下，壳聚糖的解聚速率发生了变化。在研究过程中，最大浓度的 H-MOR 导致活化能的最小增加，从 20.54kJ/mol 增加到 23.25kJ/mol。红外光谱、吸附研究和流变学评估表明，壳聚糖在多孔 H-MOR 表面上的吸附/接枝是促进解聚过程的可能机制。在优化过程中研究的极端条件下，与没有 H-MOR 进行的反应相比，H-MOR 导致 5-羟甲基糠醛（5-HMF）形成减少了三倍，氨基葡萄糖含量减少了十倍以上。因此，在受控方式下，H-MOR 的存在对于切割壳聚糖并获得所需分子量的产物以及减少杂质是必不可少的。
