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Fabrication and Mechanistic Study of Aerogels Directly from Whole Biomass
ACS Sustainable Chemistry & Engineering ( IF 7.1 ) Pub Date : 2019-10-07 , DOI: 10.1021/acssuschemeng.9b04032 Yang Liao 1 , Zhiqiang Pang 1, 2 , Xuejun Pan 1
ACS Sustainable Chemistry & Engineering ( IF 7.1 ) Pub Date : 2019-10-07 , DOI: 10.1021/acssuschemeng.9b04032 Yang Liao 1 , Zhiqiang Pang 1, 2 , Xuejun Pan 1
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Lignocellulosic aerogels were prepared directly from whole biomass Douglas fir wood without prior removal of hemicellulose and lignin using lithium bromide (LiBr) molten salt hydrate (lithium bromide trihydrate, LBTH) as a cellulose solvent via a procedure of cellulose dissolution, gelation, and regeneration. The fabricated aerogels had a homogeneous and continuous porous structure, extremely high porosity, large surface area, and very low density. The lignin-excluding aerogel had a density as low as 4.6 mg/cm3 and a porosity larger than 99%, while the lignin-including whole biomass aerogel retained almost all lignin and more than 90% of the starting biomass and had 24.9 mg/cm3 density and 98.3% porosity. A mechanistic study revealed that different from that in other cellulose solvent systems, cellulose gelation and regeneration occurred in two independent steps in the LBTH system. The weak cross-linking through a coordination effect between a cellulose hydroxyl group and Li+ cation when cooling the cellulose solution in the LBTH led to gelation, while cellulose regeneration via precipitation/aggregation due to the exchange of solvent LBTH with nonsolvent water during washing resulted in the formation of a 3D fibrous network of cellulose skeleton.
中文翻译：
直接从整个生物质气凝胶的制备和机理研究
木质纤维素气凝胶直接从整个生物量的道格拉斯冷杉木材制得，无需事先使用溴化锂（LiBr）熔融盐水合物（溴化锂三水合物，LBTH）作为纤维素溶剂通过纤维素溶解，胶凝和再生过程除去半纤维素和木质素。制成的气凝胶具有均匀且连续的多孔结构，极高的孔隙率，较大的表面积和非常低的密度。不含木质素的气凝胶的密度低至4.6 mg / cm 3，且孔隙率大于99％，而包含木质素的整个生物质气凝胶几乎保留了所有木质素和90％以上的起始生物质，并且具有24.9 mg / cm 3厘米3密度和98.3％的孔隙率。一项机理研究表明，与其他纤维素溶剂系统不同，LBTH系统中纤维素的凝胶化和再生是通过两个独立的步骤进行的。当冷却LBTH中的纤维素溶液时，通过纤维素羟基和Li +阳离子之间的配位作用而产生的弱交联导致凝胶化，而由于洗涤过程中由于溶剂LBTH与非溶剂水交换而导致的沉淀/聚集而使纤维素再生。形成纤维素骨架的3D纤维网络。
更新日期：2019-10-07
中文翻译：
直接从整个生物质气凝胶的制备和机理研究
木质纤维素气凝胶直接从整个生物量的道格拉斯冷杉木材制得，无需事先使用溴化锂（LiBr）熔融盐水合物（溴化锂三水合物，LBTH）作为纤维素溶剂通过纤维素溶解，胶凝和再生过程除去半纤维素和木质素。制成的气凝胶具有均匀且连续的多孔结构，极高的孔隙率，较大的表面积和非常低的密度。不含木质素的气凝胶的密度低至4.6 mg / cm 3，且孔隙率大于99％，而包含木质素的整个生物质气凝胶几乎保留了所有木质素和90％以上的起始生物质，并且具有24.9 mg / cm 3厘米3密度和98.3％的孔隙率。一项机理研究表明，与其他纤维素溶剂系统不同，LBTH系统中纤维素的凝胶化和再生是通过两个独立的步骤进行的。当冷却LBTH中的纤维素溶液时，通过纤维素羟基和Li +阳离子之间的配位作用而产生的弱交联导致凝胶化，而由于洗涤过程中由于溶剂LBTH与非溶剂水交换而导致的沉淀/聚集而使纤维素再生。形成纤维素骨架的3D纤维网络。
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