碱性离子液体TBAH预处理对桉木结构和酶解性能的影响

Effect of Alkaline Ionic Liquid TBAH Pretreatment on Structure and Enzymatic Properties of Eucalyptus

为探究碱性离子液体四丁基氢氧化铵(TBAH)在桉木预处理中作用机理,采用响应面分析法设计模型,得到离子液体TBAH预处理桉木的最佳条件为:预处理时间57.19 min,预处理温度71.98℃,TBAH质量分数11.78%,并验证了模型的科学性、准确性和有效性。通过对比未处理、NaOH、四丁基氟化铵(TBAF)和TBAH预处理桉木样品的组成成分,并利用傅里叶红外光谱(FT-IR)、X射线衍射(XRD)和扫描电子显微镜(SEM)来分析预处理的作用机理。研究结果表明:预处理中[TBA]+可以有效地降解木质素,降低结晶度;OH-可以降解半纤维素;在[TBA]+和OH-两者共同作用下桉木样品半纤维素由26.8%降至18.0%,木质素由26.3%降至15.0%;结晶指数由42.39%提高至54.11%;并且TBAH预处理会破坏桉木样品表面完整、致密和均匀的结构;TBAH预处理后的桉木样品经72 h酶解,还原糖产率为365.62 mg/g,纤维素转化率69.24%。

In order to explore the mechanism of the alkaline ionic liquids tetrabutylammonium hydroxide(TBAH)in the pretreatment of eucalyptus,the response surface analysis method was used to design the model,and the optimal conditions for the pretreatment of eucalyptus with ionic liquid TBAH were pretreatment time 57.19 min,pretreatment temperature 71.98℃,and TBAH mass fraction 11.78%.The model was proved to be scientific,accurate and practical.By comparing the composition of feedstock,NaOH,tetrabutylammonium fluoride(TBAF)and TBAH pretreated eucalyptus samples,Fourier infrared spectroscopy(FT-IR),X-ray diffraction(XRD)and scanning electron microscopy(SEM)were carried out for comparing the composition of feedstock with that of NaOH,tetrabutylammonium fluaride(TBAF)and TBAH pretreating eucalyptus samples,which aimed to analyze pretreatment reaction mechanism.The results showed that in the pretreatment,[TBA]+could effectively degrade lignin and reduce the crystallinity;OH-could degrade hemicellulose.Under the combined action of[TBA]+and OH-,the hemicellulose of eucalyptus samples was degraded from 26.8%to 18.0%,and the lignin was degraded from 26.3%to 15.0%;the crystallization index increased from 42.39%to 54.11%;and TBAH pretreatment would destroy the complete,dense and uniform structure of the surface of eucalyptus samples;TBAH pretreated eucalyptus wood sample was enzymatically hydrolyzed for 72 h,the yield of reducing sugar was 365.62 mg/g,and the conversion rate of cellulose was 69.24%.