Kinetics Of Dissolving Cellulose In Ionic Liquid And Enzyme Hydrolysis Process

The world is heavily depending on the crude oil to meet the increasing need of energy. As a major source of energy, the crude oil is non-renewable and its production is expected to decline dramatically in the next 50 years. There has been a strong research effort worldwide aiming at the commercialization of biomass conversion, fearing the shortages of fossil fuels. Derivatives of cellulose, such as cellulose esters and ethers, are very important commercial materials. More importantly, the broken-down components of cellulose can be used to produce ethanol through fermentation processes. However, the efficient utilization of cellulose as renewable bio-fuel is very challenging, cellulose is neither soluble in water, nor in most organic solvent, mainly due to its hydrogen-bonded supra-molecular structures. For this reason, the degradation or transformation of cellulose is usually achieved in less efficient and costly heterogeneous processes.Rate constant of dissolving cotton litter in ionic liquid was determined under isothermal conditions. Experimental results show that RTIL are non-derivatizing solvent for cellulose. After dissolution and regeneration of cellulose from RTIL solutions, the crystalline form of cellulose decreased due to the broken-down of hydrogen bonds in cotton litter. The kinetic parameters calculated show that dissolution is accompanied with small positive enthalpy and large negative entropy of activation. It is believed that the application of RTILs as solvents of cellulose will solve the pollution problem in cellulose industry and widen the application of cellulose.The initial enzymatic hydrolysis rate of carboxymethyl cellulose (CMC) vs cellulase concentration follows Michaelis-Menten equation. The adsorption of cellulase on cotton litter follows Langmuir equation and the enzymatic hydrolysis rate is not proportional to the amount of cellulase adsorbed. The modes of enzymatic hydrolysis of cotton litter and soluble cellulose are same, and adsorption might be also needed for enzymatic hydrolysis of soluble cellulose. The enzymatic hydrolysis rate for soluble cellulose is higher than that for cotton litter. Ionic liquid is a nice solvent for cellulose, for it effectively break hydrogen bonds in the supra-molecule of cellulose. Increases the surface area, compared with un-treatment cotton litter, cotton litter dissolved in ionic liquid is conducive to the saccharification process, and the largest adsorption and absorption constant of cellulase adsorbed on cotton litter is the former's 1.65 times, 1.49 times, respectively.