Impact of Ionic Liquid Pretreatment Conditions on Cellulose Crystalline Structure Using 1-Ethyl-3-methylimidazolium Acetate
Impact of Ionic Liquid Pretreatment Conditions on Cellulose Crystalline Structure Using 1-Ethyl-3-methylimidazolium Acetate
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DOI：
10.1021/jp304538v
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发表时间：
2012-08-23
影响因子：
3.3
通讯作者：
Singh, Seema
中科院分区：
文献类型：
--
作者：
Cheng, Gang;Varanasi, Patanjali;Singh, Seema
离子液体（ILs）已经被证明在预处理过程中影响木质纤维素生物质中的纤维素晶体结构，为了更好地理解纤维素的结构转化，需要系统地研究与离子液体预处理相关的膨胀和溶解过程。在这项工作中，用1-乙基-3-甲基咪唑醋酸盐[C(2)mim][OAc]和[C(2)mim][OAc]与非溶剂二甲基亚砜（DMSO）的混合物在不同温度下处理3- 20wt %微晶纤维素（Avicel）溶液。通过降低温度和增加纤维素负荷来减缓溶解过程，并通过添加DMSO进一步减缓溶解过程，从而可以深入研究溶解的中间阶段。结果表明，在[C(2)rniin][OAc]中完全溶解之前，纤维素I晶格膨胀和扭曲，沉淀后，前者的结构导致较不有序的中间结构，而完全溶解的纤维素导致纤维素II和无定形纤维素的混合物。中间结构（结晶度= 0.34）的酶解速度快于II型纤维素（结晶度= 0.54）。
Ionic liquids (ILs) have been shown to affect cellulose crystalline structure in lignocellulosic biomass during pretreatment A systematic investigation of the swelling and dissolution processes associated with IL pretreatment is needed to better understand cellulose structural transformation. In this work, 3-20 wt % microcrystalline cellulose (Avicel) solutions were treated with 1-ethyl-3-methylimidazohum acetate [C(2)mim][OAc]) and a mixture of [C(2)mim][OAc] with the nonsolvent dimethyl sulfoxide (DMSO) at different temperatures. The dissolution process was slowed by decreasing the temperature and increasing cellulose loading, and was further retarded by addition of DMSO, enabling in-depth examination of the intermediate stages of dissolution. Results' show that the cellulose I lattice expands and distorts prior to full dissolution in [C(2)rniin][OAc] and that upon precipitation the former:, structure leads to a less ordered intermediate structure, whereas fully dissolved cellulose leads to a mixture of cellulose II and amorphous cellulose. Enzymatic hydrolysis was more rapid for the intermediate Structure (crystallinity = 0.34) than for Cellulose II (crystallinity = 0.54).