Study On Using Immobilized Yeast Cells To Improve The Ethanol Fermentation Process Containing Ionic Liquids In Its Medium

Lignocellulosic materials are the richest renewable resources in the world.Production of ethanol from lignocellulosic materials has provided an effective route to solve the resource,energy and environmental problems.Use of ionic liquids can effectively convert the carbohydrates in lignocellulosic materials to fermentable sugars,but the remained ionic liquids in the obtained fermentable sugars can inhibit the yeast growth and have a negative effect on the subsequent ethanol fermentation.This work studied the ethanol fermentation process containing the ionic liquid 1-butyl 3-methyl imidazole chlorate([BMIM]Cl)in its medium by immobilizing the yeast cells using the embedding and adsorption method.The toxicity of ionic liquid [BMIM]Cl to immobilized yeast cells and its effects on the ethanol fermentation process and the reuse of the immobilized yeast cells were investigated.Firstly,the ethanol fermentation process was studied without the ionic liquid in its medium by immobilizing the yeast cells using the embedding method.Compared with the free yeast cells ethanol fermentation process,the immobilized yeast cells ethanol fermentation process at the same fermentation conditions could reach the same fermentation level and shorten the fermentation time from 72 hours to 48 hours.After that,the ethanol fermentation process was examined which contained the ionic liquid[BMIM]Cl at different concentrations in its medium by immobilizing the yeast cells using the embedding method(the ionic liquid [BMIM]Cl concentration was 10-3?10-1?1?5g/L respectively).It was found that the immobilized yeast cells could be reused 50 times and the ethanol fermentation level kept nearly unchanged.The final ethanol concentration could remained above 37 g/L after the immobilized yeast cells was reused 50 times.Then the ethanol fermentation process was investigated without the ionic liquid in its medium by immobilizing the yeast cells using the artificial zeolite adsorption method.Compared with the free yeast cells ethanol fermentation process,the immobilized yeast cells ethanol fermentation process at the same fermentation conditions could reach the same fermentation level and shorten the fermentation time from 72 hours to 48 hours.After that,the ethanol fermentation process was studied which contained the ionic liquid[BMIM]Cl at different concentrations in its medium by immobilizing the yeast cells using the artificial zeolite adsorption method(the ionic liquid [BMIM]Cl concentration was 10-3?10-1?1?5g/L respectively).It was found that the immobilized yeast cells could be reused10 times and the ethanol fermentation level kept nearly unchanged.Therefore,the sodium alginate immobilized yeast ethanol fermentation process is superior to the artificial zeolite adsorption of yeast ethanol fermentation process.The sodium alginate embedding immobilized yeast cells is a potential effective method to improve the ethanol fermentation process containing ionic liquids in its medium.