Lignocellulosic biomass is considered as the largest potential candidate to develop alternative energy, such as biofuel, biomaterial. However, the efficient conversion of cellulose and practical utilization of lignin are great challenges for sustainable biorefinery. In this study, high reducing sugar yield and different size of lignin colloid particles (LCPs) were obtained via tetrahydrofuran–water (THF–H2O) pretreatment of corn stover (CS). THF–H2O as a co-solvent, could efficiently dissolve lignin and retain cellulose. After the pretreatment, 640.87 mg/g of reducing sugar was produced, that was 6.66-fold higher than that of the untreated CS. Meanwhile, the pretreatment liquor could form spherical LCPs with different sizes ranged from 202 to 732 nm through self-assembly. We studied the optimal pretreatment condition to simultaneously realize the high reducing sugar yield (588.4 mg/g) and excellent LCPs preparation with average size of 243 nm was under TH22 (THF–H2O pretreatment at 120 °C for 2 h). To further explore the formation of LCPs with different sizes. We studied the lignin structure changes of various conditions, concluded the size of LCPs was related to the lignin concentration and syringyl/guaiacyl (S/G) ratio. As the increase of the lignin concentration and S/G, the sizes of LCPs were increased. G-type lignin was easier to dissolve in the mild pretreatment supernatant, contributing to form smaller LCPs with a good dispersibility. In the severe condition, both of S and G-type lignin were dissolved due to the lignin depolymerization, formed the larger sphere particles. This work provides a novel perspective for the technical design of lignocellulosic biomass conversion.

中文翻译：

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从玉米秸秆衍生出的高还原糖和木质素胶体颗粒

木质纤维素生物质被认为是开发替代能源（例如生物燃料，生物材料）的最大潜力候选人。然而，纤维素的有效转化和木质素的实际利用是可持续生物精炼的巨大挑战。在这项研究中，通过玉米秸秆（CS）的四氢呋喃-水（THF-H2O）预处理获得了高还原糖产量和不同尺寸的木质素胶体颗粒（LCP）。THF-H2O作为助溶剂，可以有效溶解木质素并保留纤维素。预处理后，产生640.87 mg / g的还原糖，比未处理的CS高6.66倍。同时，预处理液可通过自组装形成直径范围为202-732 nm的球形LCP。我们研究了最佳的预处理条件，以同时实现高还原糖收率（588.4 mg / g），并且在TH22（THF–H2O预处理，在120°C下进行2 h）的同时，制备了平均粒径为243 nm的优良LCP。为了进一步探索具有不同尺寸的LCP的形成。我们研究了各种条件下木质素的结构变化，得出LCPs的大小与木质素浓度和丁香基/愈创木基（S / G）比有关。随着木质素浓度和S / G的增加，LCP的尺寸增加。G型木质素更易于溶解在温和的预处理上清液中，从而有助于形成具有良好分散性的较小LCP。在严重条件下，由于木质素解聚，S型和G型木质素均溶解，形成较大的球形颗粒。