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

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0.9015 m^(2)/g和89.7%,显著提升了后续溶剂或生物酶的接触表面积。

In this study,a method for potassium hydroxide(KOH)pretreatment coupled with ternary deep eutectic solvent(DES)two-stage treat‐ment 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 cellu‐lose,hemicellulose,and lignin in eucalyptus was disrupted,while the removal rates of hemicellulose and lignin reached 83.3%and 96.5%,re‐spectively,while the retention rate of cellulose reached 91.0%.The specific surface area and relative crystallinity reached 0.9015 m2/g and 89.7%,respectively,which significantly improved the contact surface area of subsequent solvents or biological enzymes.