低共熔溶剂多级热处理高效分离杨木木质素

Efficient Separation of Poplar Lignin through Multi-stage Heat Treatment by Deep Eutectic Solvent

【目的】低共熔溶剂(DES)由于其制备简单、对木质素溶解性好、成本低和可回收性强,可用于木质纤维素生物质中木质素的提取。为了进一步提高温和条件下DES的脱木质素效果,提出逐步升温的多级处理工艺。【方法】依次在80、100和120℃下对杨木粉进行处理,每次处理时间4 h.【结果】三次处理后杨木粉木质素提取率为89.6%,相较120℃下单次处理12 h提高22.2%.通过傅里叶红外光谱、扫描电子显微镜、X射线衍射以及凝胶渗透色谱等表征探讨了处理条件对生物质分离后纤维素结构及再生木质素分子量的影响:逐步升温多次处理较单次处理可以更好地保留高结晶度纤维素,高效提取杨木粉中木质素的同时避免木质素的再聚合反应,有利于木质纤维素不同组分的分级利用。

【Purposes】Deep eutectic solvent(DES)can be used for the extraction of lignin from lignocellulosic biomass owing to its simple preparation,good solubility of lignin,low cost,and easy recycling.In order to further improve the delignification effect of DES under mild conditions,a multi-stage treatment process with gradually increasing temperature is proposed.【Methods】Poplar powder was treated at 80,100,and 120℃,and each treatment lasted for 4 h.【Findings】The lignin extraction ratio of poplar powder after three treatments is 89.6%,which is 22.2%higher than that of a single treatment at 120℃for 12 h.The effects of biomass fractionation condition on the structure of cellulose and on the molecular weight of regenerated lignin were determined by Fourier transform infrared spectroscopy,scanning electron microscopy,X-ray diffraction,and gel permeation chromatography.Compared with single treatment,multi-stage treatment by DES can retain high crystallinity cellulose better,and efficiently extracts lignin from poplar powder while avoiding lignin repolymerization,which is conducive to the graded and targeted utilization of different components of lignocellulose.