Study On Synthesis Of Sugar Ester In Biphase System Consisting Of Ionic Liquids And Supercritical Carbon Dioxide

Sugar fatty acid esters are non-ionic biosurfactants which have intriguing features such as nontoxic,nonirritant,biocompatible and biodegradable.Besides,sugar fatty acid esters have a number of excellent properties including emulsification,dispersion,solubilization,foaming and wetting function which make them attractive in oil recycling,hydrocarbon bioremediation,food,cosmetic,pharmaceutical and detergent industries.The conventional production methods of biosurfactants include chemical synthesis and enzymatic synthesis.And lipase-catalyzed synthesis of sugar eater in organic solvent has achieved a wide range of research and has been applied in industrial production.However,the used organic solvents are toxic and may cause enzyme inactivation.This paper aimed at replacing these organic solvents with ionic liquids and supercritical fluids to realize the green production of suger ester.Fristly,this study focused on synthesizing lauroyl acid glucose ester in pure ionic liquid system with glucose,lauric acid vinyl ester as raw materials and the candida Antarctica lipase B as the catalyst.The effects of reaction temperature,ratio of reactants,reaction time,the dosage of ionic liquids and the dosage of enzyme on the glucose conversion rate were investigated.The highest glucose conversion rate of81.2% could be achieved at the optimal conditions?T = 60°C,the moler ratio of glucose to lauric acid vinyl ester = 1:1,enzyme loading = 0.15 g/g glucose and ILs loading = 0.075 L/g glucose?.Based on the previous study,another typical green solvent-supercritical carbon dioxide was introduced into the reaction system.Lipase-catalyzed synthesis of lauroyl glucose ester was performed in biphasic system consisting of supercritical CO₂ and ionic liquids.The effects of reaction time,pressure,temperature,the substrate flow rate,the amount of enzyme,ratio of reactants and the amount of the IL on the glucose conversion rate were investigated.The highest glucose conversion rate of 95.3%could be achieved at the optimal conditions?T = 50 °C,P = 12 MPa,substrate flow rate = 0.2 mL/min,ILs loading = 1 mL/g celite,enzyme loading = 0.01 g/g celite andthe moler ratio of the reactants=1:2?.FTIR,NMR and LC-MC were applied to dertermine lauroyl acid glucose ester which was separated and purified by thin Layer chromatography and silica gel chromatography.Compared with conventional method,the enzymatic synthesis in biphase system consisting of ionic liquids and supercritical carbon dioxide has prominent advantages in high reaction conversion rate,short reaction time,high enzyme activity and stability,easy separation and recycle of enzyme and ionic liquids.