Ethanol Fermentation Of Cellulose Pretreated By Inioc Liquid

Celluloic ethanol is an important component of the alternative resources of petroleum. It has significance both for economic development and environmental protection. The high dense crystal structure within lignocellulose has seriously hindered its enzymatic saccharification. Pretreatment of raw materials is critical to the utilization of cellulose as resource. Traditional pretreatment methods of cellulose include physical methods, chemical methods and biological methods, all of which have some drawbacks. For example, physical methods need high consumption of energy and huge equipment into investment, chemical methods can corrode the equipment and pollute the environment, and biological methods are inefficient.Ionic liquid is a kind of"green"solvent, whose structure and properties can be adjusted. This liquid has strong stability and excellent solubility, and it can dissolve cellulose directly. In this paper, based on the pretreatment of cellulose by ionic liquids, hydrolysis saccharification and ethanol fermentation process are studied.In this research, two kinds of ionic liquids, 1-allyl-3-methylimidazolium formate ([AMIM][COOH]) and 1-butyl-3-methylimidazolium chloride ([BMIM]Cl) are synthesized; Discussed is the change of the hydrolysis rate of microcrystalline before and after pretreatment by ionic liquid under different conditions (such as heating field, temperature, time and anti-solvent). The results show that, with the increase of temperature during pretreatment, the saccharification rate of cellulose takes on a trend of rising followed by falling, the optimal temperature is 90℃. For part of cellulose molecules would be reunited if the temperature becomes too high. The hydrolysis saccharification rate of cellulose might be accelerated by increasing the pretreatment time or useing ethanol as anti-solvent. Under the best conditions (90℃, 2h, ethanol as anti-solvent), the saccharification rate of cellulose pretreated by [AMIM][COOH] and [BMIM]Cl rises 24.94% and 45.48% respectively. The change of the micro-structure of cellulose before and after pretreatment is analyzed through scanning electron microscopy (SEM) and Fourier transform infrared spectroscopy (FTIR), and the dissolving mechanism of cellulose dissolved in ionic liquids is also elaborated. The results show that cellulose pretreated by ionic liquid does not have any derivative response, which is a physical process, and the dissolving mechanism follows the Electron Donor-Acceptor (EDA) theory.The effects of producing ethanol by simultaneous saccharification and fermentation (SSF) of cellulose before and after pretreated by ionic liquid [BMIM]Cl are studied. The results shows that under the conditions of substrate concentration 250g·L^-1 and enzyme loading 33.3FPA·g^-1 cellulose, the ethanol concentration reachs 109.77g·L^-1 in SSF of cellulose pretreated by ionic liquids for 72h, and fermentation efficiency is 2.80 times of untreated cellulose under the same conditions.