Study On The Degradation And Dissolution Properties Of Chitin Biomas

At present,the production of industrial chemicals still relies on traditional petroleum resources,and with the continuous consumption of fossil fuels,its continuous supply has become a thorny issue.In addition,the environmental problems associated with petroleum resources are still high risk,so there is an urgent need to find renewable alternative resources for industrial chemical production.Due to the abundance of marine resources,if chitin biomass is used to convert it into high value-added industrial chemicals,it will not only increase economic benefits,but also have great positive significance for seawater waste management,environmental protection and solving resource crisis.Chitin biomass is rich in nitrogen elements,which can provide a large amount of nitrogen source for the preparation of many nitrogen-containing chemicals.The development of new green solvents and catalysts is also the most important topic for biomass utilization.Ionic liquids（ILs）and the closely related deep eutectic solvents（DES）as catalysts and solvent types have become the focus of research in the field of"green chemistry"in recent years.The main content of this study is to develop a series of novel green ILs as catalysts for the degradation of chitin biomass into 3-acetamido-5-acetylfuran（3A5AF）and 5-hydroxymethylfurfural（5-HMF）,the highest yield was obtained by optimizing the reaction conditions.Twelve ILs were studied,and the pyrazinyl hydrochloride ionic liquid showed good catalytic performance,and the yield of 3A5AF could reach 36.94%.Further adding boric acid and Ca Cl₂,and treating at 190℃for 60min,the conversion rate of N-acetylglucosamine（NAG）was 100%,and the yield of 3A5AF could be increased to 69.54%.Furthermore,the reaction mechanism was elucidated by ¹³C NMR and HPLC-MS.ILs also has a catalytic effect in the conversion of chitosan to 5-HMF,and the yield of 5-HMF can reach 28.22%with only triethyldiamine sulfate ionic liquid.The experimental conditions were further optimized,and the yield of 5-HMF could be increased to 45.26%.Deep eutectic solvents（DES）can be classified as a subclass of room temperature ILs because many properties and properties are similar to ILs.In this paper,the solubility of chitin biomass in alkanolamine-based deep eutectic solvents by conventional heating was investigated.The alkanolamine hydrochloride/sulfuric acid（1:1）system can rapidly dissolve chitin biomass and degrade it into small molecules.Monomers of chitin and chitosan,as well as a small number of high value-added chemicals,can be detected by HPLC-MS.In addition,the triethanolamine/lactic acid（1:4）system dissolves a small amount of chitin well,and the solubility of chitin reaches0.35%w/w by conventional heating to 170°C for 24 hours.The structural characteristics of chitin before and after dissolution were observed by FTIR and scanning electron microscopy,which confirmed the dissolution of chitin in DES.