本文選題：稻草秸稈 + 酶解糖化��； 參考：《重慶大學(xué)》2015年碩士論文

【摘要】：農(nóng)作物秸稈來源豐富,價格低廉,富含纖維素和半纖維素,是生產(chǎn)燃料酒精的重要原料。燃料酒精的制備主要包括預(yù)處理、糖化、發(fā)酵和分離提純四個階段。其中,糖化工藝既是檢驗預(yù)處理效果又是為發(fā)酵工藝提供原料的關(guān)鍵步驟。因此研究的焦點之一就是如何高產(chǎn)量低成本的獲得還原糖。本論文以稻草秸稈為原料,液化預(yù)處理后,在糖化過程中添加微量金屬離子,從優(yōu)化工藝參數(shù)出發(fā),以產(chǎn)糖量為表征,考察金屬離子的單獨作用和聯(lián)合作用對酶解糖化過程的影響,并探究金屬離子的作用機理。液化預(yù)處理結(jié)果表明,預(yù)處理后的稻草秸稈纖維素含量提高了20.9%,半纖維素和木質(zhì)素含量分別降低了12.3%和5.35%,電鏡掃描結(jié)果發(fā)現(xiàn)稻草秸稈預(yù)處理后結(jié)構(gòu)松散,比表面積和孔隙度都大大增加,有利于纖維素酶和液化底物充分接觸反應(yīng),提高酶解效果。在糖化過程中分別添加Mn2+和Fe2+離子,通過單因素實驗優(yōu)化研究金屬離子添加量、酶用量、溫度和時間對酶解糖化的影響。結(jié)果表明,在相同時間條件下,產(chǎn)糖量Fe2+離子組Mn2+離子組空白組。添加Mn2+離子時酶用量從空白組的25mg/g下降為20mg/g,添加Fe2+離子酶用量和空白組一致。適宜的酶解溫度由50℃(空白)下降為40℃(Mn2+離子)和35℃(Fe2+離子)。在糖化過程中添加Mn2+和Fe2+離子能破壞纖維素的晶型結(jié)構(gòu),增加纖維素酶和液化底物的接觸面積,同時還能提高酶活性,從而提高酶解效率,減少能耗。通過單因素實驗和正交優(yōu)化實驗考察了Mg2+和Fe3+離子的單獨作用對酶解糖化過程的影響。結(jié)果表明,空白組的較優(yōu)工藝條件為酶用量25mg/g,溫度50℃,糖化時間60h,產(chǎn)糖量343mg/g;Mg2+離子組的較優(yōu)工藝條件為Mg2+離子添加量2mg/g,酶用量20mg/g,溫度50℃,時間96h,產(chǎn)糖量高達477mg/g;Fe3+離子組的較優(yōu)工藝條件為Fe3+離子添加量4mg/g,酶用量25mg/g,溫度40℃,時間108h,產(chǎn)糖量達到400mg/g。在較優(yōu)組合條件下,添加Mg2+和Fe3+離子產(chǎn)糖量相較于空白組分別提高了134mg/g和57mg/g。這與單因素實驗所得結(jié)論在相同條件下產(chǎn)糖量Mg2+離子組Fe3+離子組空白組一致。探討了Mg2+和Fe3+離子聯(lián)合作用對稻草秸稈酶解糖化的影響。通過正交實驗得到的較優(yōu)工藝是在糖化過程中添加30mg/g纖維素酶和1:2的Mg2+、Fe3+離子,在40℃的溫度條件下酶解84h,得到346mg/g還原糖。單因素結(jié)果表明Mg2+和Fe3+離子的聯(lián)合作用比各自單獨作用更有助于酶解效率的提高。
[Abstract]:Crop stalks are rich in cellulose and hemicellulose and are important raw materials for the production of fuel alcohol. The preparation of fuel alcohol mainly includes four stages: pretreatment, saccharification, fermentation and separation and purification. Saccharification process is not only the test of pretreatment effect, but also the key step to provide raw material for fermentation process. Therefore, one of the focuses of research is how to obtain reducing sugar with high production and low cost. In this paper, straw was used as raw material. After liquefaction pretreatment, trace metal ions were added in the saccharification process. The effects of metal ions on the process of enzymatic hydrolysis and saccharification were investigated, and the mechanism of metal ions action was investigated. The results of liquefaction pretreatment showed that the cellulose content of straw was increased by 20.9%, the content of hemicellulose and lignin decreased by 12.3% and 5.35%, respectively. The results of SEM showed that the structure of straw was loose after pretreatment. The increase of specific surface area and porosity is beneficial to the full contact reaction between cellulase and liquefaction substrate and to the improvement of enzymatic hydrolysis. Mn2 and Fe2 ions were added in the saccharification process, and the effects of metal ion addition amount, enzyme dosage, temperature and time on enzymatic hydrolysis and saccharification were optimized by single factor experiment. The results showed that under the same time, the sugar production Fe2 ion group Mn2 ion group blank group. The amount of enzyme was decreased from 20 mg / g to 20 mg / g in the blank group when the Mn2 ion was added, and the amount of the enzyme was the same as that in the blank group. The optimum enzymatic hydrolysis temperature was reduced from 50 鈩，

本文編號：1903582