Abstract
This paper describes the application of Fe-MCM-48 (Mobil Composition of Matter No.48) and cellulase-MCM-48 catalysts for the depolymerization of chitosan. The results show that H2O2 is a good oxidant for the depolymerization of chitosan in the presence of Fe-MCM-48. The average polymerization degree of the product decreased to 6.1, and decreased to 29.2 when cellulase-MCM-48 was used as a catalyst, because the effect of the enzyme was affected by the molecular structure of chitosan. When both materials were used for depolymerization, the average degree of polymerization sharply decreased to 3.8. The results show that the two degradation methods can promote each other to obtain oligosaccharides with a lower degree of polymerization. This provides a new method for the controllable degradation of chitosan and lays a good foundation for the industrial production of chitosan oligosaccharides with a low degree of polymerization.
Highlights
Chitosan, known as deacetylated chitin, is deacetylated in concentrated alkali or by an enzyme from chitin that exists widely in nature
H2 O2 is a good oxidant for depolymerization of chitosan; it can generate active free radicals for cellulase-MCM-48 as the heterogeneous catalyst
This indicates that homogeneous hydrogen peroxide depolymerized chitosan a lot in the presence of Fe-MCM-48, which weakened the steric hindrance, cellulase-MCM-48 can decompose chitosan with low molecular mass by breaking the glycosidic bonds
Summary
Known as deacetylated chitin, is deacetylated in concentrated alkali or by an enzyme from chitin that exists widely in nature. Bioenzymatic degradation uses specific enzymes to degrade chitosan, featuring no side effects, mild degradation conditions, and easy control of molecular weight distribution of degradation products [10,14], but production costs are high because the enzymes are usually expensive. 600 W power to obtain a chito-oligosaccharide with a molecular weight of 5500 Da. In the reaction using a biological enzyme to degrade chitosan, free enzymes in the mixture are difficult to recycle after the reaction, increasing the production cost. The MCM-48 molecular sieve, a silicon-based mesoporous material, has a stable and well-organized three-dimensional spiral porous structure, and it has attracted great attention in the catalytic field due to its advantages, including high specific surface area and adjustable pore size [24]. Characteristics of immobilized catalysts and degradation products were analyzed to obtain chito-oligosaccharide with a controllable polymerization degree in an efficient and low-cost manner, laying the foundation for economic production of chito-oligosaccharide
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