In the context of promoting a circular bioeconomy, the development of green and efficient lignocellulosic biomass pretreatment technologies so as to realize high value-added biomass utilization is of intense interest. We demonstrated the potential of the bio-based green solvent dimethyl isosorbide (DMI) for the fractionation of Eucalyptus biomass with excellent performance. Here, to investigate the mechanisms involved in biomass fractionation, microimaging and microspectroscopic techniques were employed together with molecular dynamics (MD) simulation and COSMO-RS quantum chemical calculations to derive multiscale information. Both the microstructure and regional chemistry of the cell wall vary significantly with the volume ratio of DMI/H₂O. The strongest effects were found at DMI/H₂O = 9 : 1 and showed visible cell wall tearing cracks and cell wall deformation and collapse as well as the lowest values of cell wall thickness and circularity. From the MD simulations, lignin exhibits collapsed-like structure in pure H₂O with low solvent accessibility surface area (SASA) and radius of gyration (R_g). In contrast, lignin in DMI/H₂O shows extended structure with high SASA and solvent interactions dominated by van der Waals forces, with maximal contact in the 9 : 1 (v/v) system. Further, the COSMO-RS calculated sigma (σ-) potential suggests the intermolecular interactions in DMI and DMI/H₂O co-solvent are weak, leading to stronger interaction with lignin and correspondingly higher lignin dissolution. The radial distribution functions and σ-potential all show that again DMI/H₂O at 9 : 1 is an optimal volume ratio for high lignin dissolution. This study provides a solvent-ratio dependent mechanism for the action of polar aprotic solvents in the deconstruction of biomass.

中文翻译：

---

异山梨醇二甲酯/水共溶剂预处理系统生物质解构机理的多尺度研究

在推动循环生物经济的背景下，发展绿色高效的木质纤维素生物质预处理技术，实现生物质的高附加值利用备受关注。我们展示了生物基绿色溶剂二甲基异山梨醇（DMI）在桉树生物质分馏方面的潜力，具有优异的性能。在这里，为了研究生物质分馏所涉及的机制，将显微成像和显微光谱技术与分子动力学 (MD) 模拟和 COSMO-RS 量子化学计算结合起来，以获得多尺度信息。细胞壁的微观结构和区域化学性质随 DMI/H _{2 O 体积比的变化而显着变化。当 DMI/H 2} O = 9:1时效果最强，并表现出可见的细胞壁撕裂裂纹和细胞壁变形。塌陷以及细胞壁厚度和圆形度的最低值。从 MD 模拟来看，木质素在纯 H ₂ O 中表现出塌陷状结构，具有低溶剂可及表面积 (SASA) 和回转半径 ( R _g )。相比之下，DMI/H ₂ O 中的木质素显示出具有高 SASA 的扩展结构和以范德华力为主的溶剂相互作用，在 9 : 1 (v/v) 系统中具有最大接触。此外，COSMO-RS计算的西格玛( σ- )势表明DMI和DMI/H ₂ O共溶剂中的分子间相互作用较弱，导致与木质素的相互作用更强，相应地更高的木质素溶解。径向分布函数和σ势都再次表明9:1的DMI/H ₂ O是高木质素溶解的最佳体积比。这项研究为极性非质子溶剂在生物质解构中的作用提供了溶剂比依赖性机制。