| 摘要: |
| 【目的】研究氯化胆碱/乳酸（choline chloride/lactic acid,ChCl/Lac）低共熔溶剂（deep eutectic solvents,DESs）对杨木的预处理效果，及稀酸、稀碱和水在ChCl/Lac预处理杨木过程中的协同效果，为利用杨木制备可发酵糖提供依据。【方法】以粉碎的杨木原料为试验材料，采用ChCl/Lac（物质的量比为1∶2）及质量分数1% H2SO4、质量分数1% Na2CO3和去离子水分别协同ChCl/Lac预处理杨木，每种预处理方式均设置120，150和170 ℃ 3个温度，分析不同预处理方法对杨木化学组成、结构形态及酶水解效率的影响。【结果】ChCl/Lac预处理及1% H2SO4、1% Na2CO3和去离子水分别协同ChCl/Lac预处理对杨木中的半纤维素和木质素均有比较好的脱除效果，其中在反应温度大于150 ℃时，1% H2SO4协同ChCl/Lac预处理可以使杨木中的半纤维素和木质素的脱除率分别达到96%和71%以上，效果最好；与ChCl/Lac预处理相比，去离子水协同ChCl/Lac预处理对木质素的脱除反而有抑制作用。与杨木原料相比，各种预处理方式均提高了杨木样品的结晶度和纤维素含量，并增强了杨木样品的热稳定性。1% H2SO4协同ChCl/Lac在150 ℃预处理后可使样品72 h酶水解的葡萄糖得率达96.3%，是杨木原料(16.8%)的5倍以上。与ChCl/Lac预处理相比，1% Na2CO3和去离子水协同处理对酶水解效率没有明显促进效果。【结论】1% H2SO4协同ChCl/Lac预处理可明显提高杨木中半纤维素和木质素的脱除率及杨木的结晶度、破坏杨木的纤维结构、降低结构强度、影响热稳定性，进而有效提高杨木酶水解效率。 |
| 关键词: 低共熔溶剂 氯化胆碱/乳酸 杨木预处理 酶水解 |
| DOI： |
| 分类号: |
| 基金项目:国家“十三五”重点研发项目（2017YFD0601001） |
|
| Effects of choline chloride/lactic acid deep eutectic solvents pretreatment on enzymatic hydrolysis of poplar |
|
ZHOU Mingu,GUO Yingjie,HAO Ziyue,et al
|
| Abstract: |
| 【Objective】This study analyzed effects of choline chloride/lactic acid (ChCl/Lac) deep eutectic solvents (DESs) on poplar and understood the synergistic effect of sulfuric acid,sodium carbonate and water to provide basis for preparing fermentable sugar from poplar.【Method】ChCl/Lac (1∶2,molar ratio),and combination of ChCl/Lac with 1% sulfuric acid （mass fraction）,1% sodium carbonate （mass fraction）and deionized water were prepared as pretreatment reagents to treat poplar under three temperature settings of 120,150 and 170 ℃.The effects of employed pretreatments on structure morphology and chemical composition of poplar as well as efficiency of enzymatic hydrolysis were investigated.【Result】The ChCl/Lac pretreatment as well as the 1% H2SO4,1% Na2CO3 and deionized water synergistic ChCl/Lac pretreatments had good effects on removing hemicelluloses and lignins from poplar.The 1% H2SO4 synergistic ChCl/Lac pretreatments removed 96% hemicelluloses and 71% lignins from poplar when the reaction temperature was over 150 ℃.However,the deionized water synergistic process had inhibited effect on lignin removal from poplar.All the employed pretreatment methods increased crystallinity and cellulose content,and enhanced thermal stability of poplar.When the pretreatment temperature was 150 ℃,1% H2SO4 synergistic ChCl/Lac pretreatment glucose yield was 96.3% (enzymatic hydrolysis 72 h),which was enhanced by over 5 times in comparison to poplar without treatment (16.8%).The 1% Na2CO3 and deionized water synergistic ChCl/Lac pretreatments had no promoting effects on enzymatic hydrolysis efficiency of poplar.【Conclusion】The employed 1% H2SO4 and ChCl/Lac co-pretreatments effectively improved removal rate of hemicellulose and lignin from poplar and the crystallinity of poplar,destructed the fiber structure,decreased the structure strength,and influenced thermal stability of poplar.Thus,the enzymatic hydrolysis efficiency of poplar was improved. |
| Key words: deep eutectic solvents choline chloride/lactic acid poplar pretreatment enzymatic hydrolysis |
