Imidazolium Ionic Liquid-based Salting/sugaring-out Extraction Of 2,3-butanediol

2,3-Butanediol(2,3-BD)is one of the C4 platform chemicals with wide applications in chemistry,pharmaceutics,food industry,fuel industry,and aerospace industry.Due to its high hydrophilicity and complicated components of the fermentation broth downstream processing becomes the bottle-neck of industrialization of 2,3-BD.With organic solvents as extraction reagent and inorganic salts as salting-out reagent,salting-out extraction showed the advantages of high recovery,low energy consumption and easy scale-up.When the inorganic salt was replaced by sugar,the bottom phase could be used for fermentation,thus the amount of wastewater for treatment and discharge was reduced.Ionic liquids(ILs)have no detectable vapor pressure,so the safety problem caused by flammable and explosive solvents could be avoided.In this thesis,the separation of 2,3-BD from fermentation broth was investigated by salting-out and sugaring-out extraction using imidazolium ionic liquids,the partition behavior of 2,3-BD and ILs were studied and the effects of ILs on the growth and metabolism of Enterobacter cloacae DLM were explored.Firstly,IL-based salting-out extraction of 2,3-butanediol from fermentation broth was investigated.Based on the recovery of 2,3-BD and ionic liquid two systems of K2HPO4/1-butyl-3-methylimidazolium chloride([Bmim][Cl])and K2HPO4/1-ethyl-3-methylimidazolium trifluoromethanesulfonate([Emim][OTF])were screened from different IL-inorganic salt systems.The effects of temperature,2,3-BD concentration and fermentation broth components on the phase formation was explored,and the partition behavior of 2,3-BD,ILs,residual sugar and organic acids were studied.In the range of 10-20%(w/w)[Bmim][Cl],the partition coefficient of 2,3-BD was increased first then decreased with increasing concentration of K2HPO4,while decreased at 30% [Bmim][Cl].When [Emim][OTF]/K2HPO4 was applied,the partition coefficient of 2,3-BD was increased with increasing concentration of K2HPO4.When the system was consisted of 30%[Bmim][Cl] and 10% K2HPO4,the recovery rates of 2,3-BD and IL were 96.3% and 97.5%,respectively,and glucose removal was 30.2%.When the system was composed of 25% [Emim][OTF] and 30% K2HPO4,recovery of 95.7% for 2,3-BD and 99.5% for IL was obtained,and the removal of lactic and succinic acids was 63.3% and 89.7%,respectively.Secondly,IL-based sugaring-out extraction of 2,3-BD was explored.The effects of IL structure,concentration and K2HPO4 addition on phase separation and recovery of 2,3-BD and IL were explored,and the distribution of 2,3-butanediol and IL were investigated in different ILs/glucose systems.The phase ratio was decreased and the partition coefficients of 2,3-BD and IL were increased with increasing concentration of glucose.When the system composition was 25% glucose,28% [Emim] [OTF],and 4% K2HPO4,the partition coefficients of 2,3-BD and IL were 2.04 and 5.71,and recovery were 63.1% and 82.8%,respectively.Finally,the effects of ionic liquids on the growth and metabolism of E.cloacae DLM were studied.The IC50 values of 4 ILs were determined,and the growth curves at different IL concentrations were made which demonstrated growth stimulation at low IL concentration and inhibition at high concentration.Product analysis showed different IL had different inhibition on different pathways and isomer ratio of 2,3-BD.The detection of extracellular protein and extracellular nucleic acids indicated that the permeability of cell membrane was increased with IL addition.