Study On Characteristics Of Substrate Preatreated By Steam-Explosion And Acid-Catalysis Ethanol Method

The cellulose in the raw materials is mainly used in preparation of bio-ethanol conversion. After the pretreatment, cellulose is converted into glucose by cellulose, then ethanol is achieved with a further fermentation. In order to improve the hydrolysis rate of fiber, raw materials must be pretreated.Chinese triploid poplar was selected as raw material in this research and pretreated by acid-catalysis ethanol method and steam explosion. RSM (Response surface Methodology) was used to optimize the conditions of pretreatments. then the mathematical model between characteristics of raw material and conditions of pretreatment was established and internal connection between conditions of pretreatment and indexes such as yield of cellulose, crystallinity index and lignin content were quantitatively described. The effect on the properties of substrates by acid-catalysis ethanol and steam explosion were preliminary analyzed and compared. The optimum process of acid-catalysis ethanol pretreatment were obtained as:Ethanol consistency:45%, temperature:185℃, ratio of wood to liquor:1:4.2and holding time:41min. The optimum process of steam explosion pretreatment was found to be:Pressure:1.80Mpa and holding time:293s. Individually under the optimum process of acid-catalysis ethanol and steam explosion pretreatments, yield of cellulose were82.62%and80.62%, crystallinity index were1.712and1.946, lignin content were7.24%and14.03%.Triploid was pretreated by optimum process of acid-catalysis ethanol method, steam explosion and dilute acid impregnated steam explosion, which result of cellulose, holocellulose and lignin content, crystallinity index, FTIR, polymerization degree and both of length and width of the fiber were compared. Both of the celluloses were degraded but not much, the structure of lignin was destroyed and a large portion of lignin and hemicellulose were removed, the acid-catalysis ethanol method was more effective. Based on an overall consideration of the result, the solids obtained from acid-catalysis ethanol pretreatment were selected as the material of enzyme hydrolysis research.The result of effect of metal ions on enzyme activity showed that CMC enzyme activity can be activated by metal ions within the experimental concentration limits, among of which activation effect of Fe2+, Cu2+were obvious. Fe2+, Mg2+at low concentration and a restricted concentration range of Cu2+and Zn2+had significant activation on filter paper activity. After single factor experiments, the optimum process of enzyme hydrolysis were obtained as:temperature:50℃, H value:5.0, solid concentration:2.0%, cellulose dosage:251U, rotating speed:160r/min. Glucose conversion rate of material treated by the optimum process of both pretreatment and enzyme hydrolysis under could reach to95.34%after78H when the concentration of Fe2+was1.2mg/ml.