Yuanxin Wu

Investigation of the toxicity of the ionic liquid 1-butyl-3-methylimidazolium chloride to Saccharomyces cerevisiae AY93161 for lignocellulosic ethanol production

Ionic liquid (IL) pretreatment of lignocellulosic materials has provided a new technical tool to improve lignocellulosic ethanol production. To evaluate the influence of the residual IL in the fermentable sugars from enzymatic hydrolysis of IL pretreatment of lignocellulosic materials on the subsequent ethanol fermentation, the toxicity of the IL 1-butyl-3-methylimidazolium chloride ([BMIM]Cl) to Saccharomyces cerevisiae AY93161 was investigated. Firstly, the morphological structure, budding and metabolic activity of Saccharomyces cerevisiae AY93161 at different [BMIM]Cl concentrations were observed under an optical microscope. The results show that its single cell morphology remained unchanged at all [BMIM]Cl concentrations, but its reproduction rate by budding and its metabolic activity decreased with the [BMIM]Cl concentration increasing. The half effective concentration (EC50) and the half inhibition concentration (IC50) of [BMIM]Cl to Saccharomyces cerevisiae AY93161 were then measured using solid and liquid suspension culture and their value were 0.53 and 0.39 g.L-1 respectively. Finally, the influence of [BMIM]Cl on ethanol production was investigated. The results indicate that the [BMIM]Cl inhibited the growth and ethanol production of Saccharomyces cerevisiae AY93161. This toxicity study provides useful basic data for further development in lignocellulosic ethanol production by using IL technology and it also enriches the IL toxicity data.

Coproduction of xylose, lignosulfonate and ethanol from wheat straw.

A novel integrated process to coproduce xylose, lignosulfonate and ethanol from wheat straw was investigated. Firstly, wheat straw was treated by dilute sulfuric acid and xylose was recovered from its hydrolyzate. Its optimal conditions were 1.0wt% sulfuric acid, 10% (w/v) wheat straw loading, 100°C, and 2h. Then the acid treated wheat straw was treated by sulfomethylation reagent and its hydrolyzate containing lignosulfonate was directly recovered. Its optimal conditions were 150°C, 15% (w/v) acid treated wheat straw loading, and 5h. Finally, the two-step treated wheat straw was converted to ethanol through enzymatic hydrolysis and microbial fermentation. Under optimal conditions, 1kg wheat straw could produce 0.225kg xylose with 95% purity, 4.16kg hydrolyzate of sulfomethylation treatment containing 5.5% lignosulfonate, 0.183kg ethanol and 0.05kg lignin residue. Compared to present technology, this process is a potential economically profitable wheat straw biorefinery.

Influence of Ionic Liquid 1- butyl-3-methylimidazolium Chloride on the Soil Micro-Ecological System

In order to evaluate the influence of ionic liquid 1- butyl-3-methylimidazolium chloride ((Bmim)Cl) on the soil micro-ecological system, the toxicity of (Bmim)Cl to soil microorganisms and its impact on soil physico-chemical properties were investigated. Three soil samples, which were taken from the rape land, nursery land and the broad bean land respectively, were used for this study. The toxicity test results show that the (Bmim)Cl inhibited the growth of soil microorganisms including bacteria and actinomycetes. This inhibition became stronger with the (Bmim)Cl concentration increasing. The EC50 of soil bacteria was close to that of the Vibrio fischeri, and the EC50 of soil actinomycetes was near to that of the Pseudokirchneriella subcapitata. The soil physico-chemical properties test results indicate that the organic mass and the soluble salts in soil increased with the increase of the (Bmim)Cl concentration. The (Bmim)Cl also caused the pH change in the soil micro-ecological system. It suggests that the ionic liquid (Bmim)Cl would influence the soil mi- cro-ecological system by inhibiting the growth of soil microorganisms and altering the soil physico-chemical properties when it contaminated the soil system.

Microcalorimetric Investigation of the Effect of the Ionic Liquid 1-Butyl-3-Methylimidazolium Chloride on the Fermentation of Saccharomyces cerevisiae AY93161 for Lignocellulosic Ethanol Production

The effects of ionic liquid 1-butyl-3-methylimidazolium chloride (BMIMCl) on the ethanol fermentation process of Saccharomyces cerevisiae AY93161 were investigated by using microcalorimetry. On the basis of microcalorimetric and process data, the thermokinetic parameters of the ethanol fermentation process at different BMIMCl concentrations from 0.001 to 5 gL were calculated. Compared to the control, the BMIMCl caused a decreased value of the maximum specific growth rate μm (from 0.226 to 0.105 h), and an increased value of the maximum specific produced heat rate pm (from 2.08 to 7.06 mWlg ) and the total heat output H for producing 1 g ethanol (from 990 to 1871 Jg). The decreased μm and increased pm and H led to lower final yeast concentration (from 3.85 to 2.39 gL) and ethanol concentration (from 40.3 to 25.1 gL). This gives useful information for improving the lignocellulosic ethanol production process using the ionic liquid technology.