碱-羟甲基化预处理对甘蔗渣酶解和发酵效率的影响

Effect of Alkali-hydroxymethylation Pretreatment on Sugarcane Bagasse Enzymatic Hydrolysis and Fermentation Efficiency

以甘蔗渣(SCB)为原料,经1.4%氢氧化钠处理制得碱处理甘蔗渣(AP-SCB),再经羟甲基化反应制备碱-羟甲基化预处理甘蔗渣(AHP-SCB),考察甲醛用量对提高甘蔗渣酶水解效率和乙醇发酵得率的影响。实验结果表明:在甘蔗渣碱-羟甲基预处理过程中,当甘蔗渣与甲醛质量比为1∶1.5,预处理2 h后,木质素脱除率为55.68%;在纤维素酶用量为20 FPIU/g(以葡聚糖质量计)时,72 h酶水解得率为89.61%,较未处理甘蔗渣(水解得率9.09%)提高了8.86倍;酶水解液经24 h发酵后,乙醇质量浓度从10.93 g/L(AP-SCB)增加至12.96 g/L(AHP-SCB-1.5)。通过红外光谱分析预处理前后物料结构的变化,并进行疏水度和酶可及度的测定,AHP-SCB-1.5的疏水度(0.127 L/g)和酶可及度(505.73 mg/g)分别是AP-SCB的64.64%和1.11倍;碱和羟甲基化反应在预处理中起到协同作用,改善甘蔗渣的亲水性和酶可及性。

To investigate the effects of formaldehyde dosage on improving enzymatic hydrolysis efficiency and ethanol fermentation yield of sugarcane bagasse,the sequential NaOH and hydroxymethylation pretreatment(AHP)were used to treat sugarcane bagasse(SCB)with different proportion of formaldehyde by hydroxymethylation reaction.The results showed that when SCB was treated by AHP with substrate and formaldehyde ratio of 1∶1.5 for 2 h,the delignification rate was 55.68%and the mass fraction of cellulose was 67.20%.Under the cellulase dosage of 20 FPIU/g(based on the mass of glucan),the 72 h glucose yield was 89.61%,which was 8.86 times higher than that of untreated SCB(9.09%).After 24 h fermentation,the ethanol concentration increased from 10.93 g/L of AP-SCB to 12.96 g/L of AHP-SCB-1.5.The structural features of the pretreated sugarcane bagasse were measured by FT-IR,and the hydrophobicity and cellulase accessibility were studied.The hydrophobicity(0.127 L/g)and enzymatic accessibility(505.73 mg/g)of AHP-SCB-1.5 were 64.64%and 1.11 times of AP-SCB,respectively.The results showed that alkali and hydroxymethylation had a synergistic effect on pretreatment process,which could improve the hydrophilicity and cellulase accessibility of materials.