ICGM, Univ Montpellier, CNRS, ENSCM, Montpellier, France.
Langmuir. 2020 Dec 1;36(47):14403-14416. doi: 10.1021/acs.langmuir.0c02794. Epub 2020 Nov 17.
Understanding and controlling the physical adsorption of lignin compounds on cellulose pulp are key parameters in the successful optimization of organosolv processes. The effect of binary organic-aqueous solvents on the coordination of lignin to cellulose was studied with molecular dynamics simulations, considering ethanol and acetonitrile to be organic cosolvents in aqueous solutions in comparison to their monocomponent counterparts. The structures of the solvation shells around cellulose and lignin and the energetics of lignin-cellulose adhesion indicate a more effective disruption of lignin-cellulose binding by binary solvents. The synergic effect between solvent components is explained by their preferential interactions with lignin-cellulose complexes. In the presence of pure water, long-lasting H-bonds in the lignin-cellulose complex are observed, promoted by the nonfavorable interactions of lignin with water. Ethanol and acetonitrile compete with water and lignin for cellulose oxygen binding sites, causing a nonlinear decrease in the lignin-cellulose interactions with the amount of the organic component. This effect is modulated by the water exclusion from the cellulose solvation shell by the organic solvent component. The amount and rate of water exclusion depend on the type of organic cosolvent and its concentration.
理解和控制木质素化合物在纤维素纸浆上的物理吸附是成功优化有机溶剂法工艺的关键参数。本文采用分子动力学模拟研究了二元有机-水溶剂对木质素与纤维素配位的影响，将乙醇和乙腈作为有机共溶剂在水溶液中与它们的单一组分进行了比较。考虑到纤维素和木质素周围溶剂化壳的结构以及木质素-纤维素黏附的热力学，二元溶剂更有效地破坏了木质素-纤维素的结合。溶剂成分之间的协同作用可以通过它们与木质素-纤维素复合物的优先相互作用来解释。在纯水中，观察到木质素-纤维素复合物中存在持久的氢键，这是由于木质素与水的不利相互作用所致。乙醇和乙腈与水和木质素竞争纤维素氧结合位点，导致木质素-纤维素相互作用随有机成分数量的非线性减少。这种效应受到有机溶剂成分从纤维素溶剂化壳中排斥水的调节。水的排斥量和速率取决于有机共溶剂的类型及其浓度。
