亚氯酸钠和氢氧化钠两步预处理杨木制备低聚木糖和单糖  

Production of Xylooligosaccharides and Monosaccharides from Poplar by Two-step Sodium Chlorite and Sodium Hydroxide Pretreatment

作　　者：方鑫 文沛瑶 徐勇[1] 张军华[1,2] FANG Xin;WEN Peiyao;XU Yong;ZHANG Junhua(College of Chemical Engineering,Nanjing Forestry University,Nanjing 210037,China;College of Forestry,Northwest A&F University,Yangling 712100,China)

机构地区：[1]南京林业大学化学工程学院,江苏南京210037 [2]西北农林科技大学林学院,陕西杨凌712100

出　　处：《林产化学与工业》2021年第5期23-30,共8页Chemistry and Industry of Forest Products

基　　金：国家重点研发计划资助项目(2017YFD0601001);南京林业大学科研启动基金(163030103)。

摘　　要：以杨木为研究对象,考察了亚氯酸钠(SC)和氢氧化钠(SH)两步预处理对杨木组成的影响,探讨了酶法制备低聚木糖(XOS)和单糖的特性。研究结果表明:亚氯酸钠预处理能选择性地脱除杨木木质素,杨木经质量分数6%的亚氯酸钠在70℃下处理3 h,木质素移除率达到65.8%,葡聚糖和木聚糖的保留率分别为90.7%和92.4%。X射线衍射和X射线光电子能谱仪分析表明,亚氯酸钠预处理移除了底物中的总木质素和表面的木质素,提高了底物结晶度,增加了底物的可及性。杨木经70℃的亚氯酸钠和50℃的氢氧化钠预处理后,葡聚糖质量分数为67.8%,木聚糖的质量分数为21.5%,木质素质量分数为2.9%。固体残渣经木聚糖酶水解后低聚木糖得率达到47.2%,其中木二糖占低聚木糖总量的98%以上。与单独亚氯酸钠预处理(6%,70℃,3 h)相比,氢氧化钠预处理将低聚木糖得率提升了7.1倍。经过木聚糖酶水解后,两步预处理的杨木残渣经30 mg/g的纤维素酶(以底物质量计)水解,葡萄糖得率高达90.2%。最终,1 kg杨木可获得52.5 g的低聚木糖、317.6 g葡萄糖和49.9 g木糖。In this work,the effects of sodium chlorite(SC)and sodium hydroxide(SH)pretreatments on the chemical composition of poplar were investigated.The preparation of xylooligosaccharides(XOS)and monosaccharides by enzymatic hydrolysis was discussed.The results showed that poplar lignin could be selectively removed by SC pretreatment.After 6%SC pretreatment at 70℃for 3 h,the removal of lignin reached 65.8%,whereas 90.7%glucan and 92.4%xylan were retained.The data of X-ray diffraction and X-ray photoelectron spectroscopy indicated that SC pretreatment removed the total lignin in poplar and the surface lignin on poplar,and increased the crystallinity and accessibility of the substrate.After the pretreatment with 6%SC at 70℃and 1%SH at 50℃,the contents of glucan,xylan,and lignin in the pretreated poplar were 67.8%,21.5%,and 2.9%,respectively.The highest XOS yield of 47.2%from the SC-SH-pretreated poplar by xylanase hydrolysis was obtained,and the XOS preparation was composed of 98%xylobiose.Compared with the poplar treated by 6%SC at 70℃for 3 h,SH pretreatment increased the yield of XOS by 7.1 times.After the hydrolysis by xylanase,the glucose yield of two-step pretreated poplar residue was 90.2%with a cellulase lading of 30 mg/g dry matter.Finally,52.5 g XOS,317.6 g glucose and 49.9 g xylose were obtained from 1 kg raw poplar.The results of this work provided a theoretical guidance for the preparation of XOS and monosaccharides from poplar under mild conditions.

关 键 词：杨木 亚氯酸钠 氢氧化钠 低聚木糖 酶水解 

分 类 号：TQ35[化学工程]