碱预处理耦合三元DES体系对提高桉木组分分离效率的研究

Study on Improving the Components Separation Efficiency of Eucalyptus by Alkali Pretreatment Coupled with Ternary DES System

关键词:  低共熔溶剂  组分分离  半纤维素  木质素  响应面法

Key Words:DES  component separation  hemicellulose  lignin  response surface method

摘要:本研究探索了一种氢氧化钾预处理耦合三元低共熔溶剂（DES）两段处理法，并用于分离桉木组分。首先采用单因素和Box-Behnken法优化了碱预处理分离桉木半纤维素的工艺条件，然后探究了碱预处理耦合三元DES两段处理桉木的微观形貌、比表面积、结晶度等。结果表明，优化后的氢氧化钾处理工艺条件为：处理温度76 ℃、处理时间5 h、氢氧化钾质量分数15%，此时半纤维素去除率可达（77.1±0.2)%。经碱预处理耦合三元DES（固液比1∶20（g∶mL）、反应时间30 min、反应温度90 ℃）两段处理后，桉木中纤维素、半纤维素和木质素形成的致密结构被打破，半纤维素去除率达83.3%，木质素去除率达96.5%，纤维素保留率达91.0%，比表面积和相对结晶度分别达0.901 5 m²/g和89.7%，显著提升了后续溶剂或生物酶的接触表面积。

Abstract:In this study， a method for potassium hydroxide （KOH） pretreatment coupled with ternary deep eutectic solvent （DES） two-stage treatment was explored for component separation of eucalyptus. Initially， the KOH pretreatment conditions for separating hemicellulose from eucalyptus were optimized using methods of single-factor and Box-Behnken design. Subsequently， the microscopic morphology， specific surface area， and crystallinity of eucalyptus treated by KOH prepretreatment coupled with the ternary DES two-stage treatment were investigated. The results showed that the optimized KOH pretreatment conditions were determined as treatment temperature of 76 ℃， treatment time of 5 h， KOH mass fraction of 15%， at which the hemicellulose removal rate could reach （77.1±0.2）%. Following the KOH pretreatment coupled with ternary DES two-stage treatment （solid-liquid ratio of 1∶20（g∶mL）， reaction time of 30 min， and reaction temperature of 90 ℃）， the dense structure formed by cellulose， hemicellulose， and lignin in eucalyptus was disrupted， while the removal rates of hemicellulose and lignin reached 83.3% and 96.5%， respectively， while the retention rate of cellulose reached 91.0%. The specific surface area and relative crystallinity reached 0.901 5 m²/g and 89.7%， respectively， which significantly improved the contact surface area of subsequent solvents or biological enzymes.