Construction And Application Of Macromolecular Extraction System Based On Deep Eutectic Solvent

Deep eutectic solvent was first proposed by Abbott et al.in 2003.Through the development of deep-temperature eutectic research,it was found that quaternary ammonium salts can form a eutectic system with amide compounds under low temperature conditions.In addition to the excellent characteristics of ionic liquids,eutectic solvents also have the characteristics of low toxicity,simple synthesis,and low price.Therefore,they are also known as new green solvents.These excellent properties greatly broaden the application range of eutectic solvents,and their use in mixture separation and extraction has attracted widespread attention.This thesis starts with the synthesis of eutectic solvents from alcohols as hydrogen bond donors and choline chloride as hydrogen bond acceptors to extract protein macromolecules in soybeans.And further change the types of hydrogen bond acceptors and donors,study the hydrogen bond displacement of eutectic solvents,and establish research methods for hydrogen bond interactions.Explore its application in the extraction of macromolecules,and achieved some beneficial results.The specific research content is as follows:(1)Using soy protein as a model and deep eutectic solvent as the extraction solvent,the effects of key factors on the extraction of soy protein based on monitoring its molecular properties were systematically studied.The conditions for the recovery of soy protein from deep eutectic solvents were explored and optimized using the response surface methodology.In addition,the influence of deep eutectic solvents on the structure and physicochemical properties of soy protein was studied using various characterization techniques.The results showed that the hydrogen bonding interaction in deep eutectic solvent could affect the protein extraction,and the hydrophobic interaction also played an important role in the protein extraction.Moreover,deep eutectic solvent caused protein denaturation and other changes in the protein,thus affecting the further applications of soy proteins.This study should provide reference and guidance for green extraction of other proteins by deep eutectic solvents in laboratory or industry,and provide a basis for the utilization of soy or other proteins extracted from such processes.(2)Using choline chloride,choline bromide,choline iodide synthesis deep eutectic solvent as the research object,the influence of the ratio and the amount of water added on the physical and chemical properties are studied.According to the synthesis of the eutectic solvent and the morphological performance at room temperature,nuclear magnetic resonance characterization methods are used to find the change law of hydrogen bonds in the eutectic solvent from the molecular level.The results show increasing the mole ratio of hydrogen bond donor ethylene glycol is more conducive to the formation of a uniform and stable solution at room temperature from deep eutectic solvent.However,increasing the molar ratio of hydrogen bond donor oxalic acid to urea in deep eutectic solvent is not conducive to the formation of a uniform and stable solution at room temperature by the eutectic solvent.At the same time,choline chloride has a stronger ability to form hydrogen bonds than choline bromide and choline iodide,which makes choline chloride more conducive to the synthesis of eutectic solvents and remains liquid at room temperature.This research provides reference and guidance for the change of hydrogen bond displacement in synthetic liquid eutectic solvents in the laboratory or industry.(3)Using Dendrobium officinale Kimura et Migo as the research object and hydrogen bond donor,eight hydrogen bond acceptors were selected to synthesize eutectic solvents.The viscosity and temperature change trend of 8 eutectic solvents under different experimental conditions were studied,the sugar content in deep eutectic solvent was determined by phenol-sulfuric acid method.The results show the addition of choline chloride make the extraction efficiency of polysaccharides reach 37.02%,which is higher than the extraction efficiency of polysaccharides in the blank group(33.14%).At the same time,glucose is used to simulate hydrogen bond donor molecules,and nuclear magnetic resonance technology is used to characterize the influence of different types of hydrogen bond acceptors on their hydrogen bond displacement.The results show the hydrogen bond strength between choline chloride and glucose is higher than that of other hydrogen bond acceptor molecules and glucose.In addition,by studying the viscosity of 8 eutectic solvents,deep eutectic solvents formed have greater viscosity and can be used to bond different materials.This research provides a relevant basis for the extraction of polysaccharides and natural adhesives from Dendrobium officinale Kimura et Migo in the laboratory or industry.