Ethanol organosolv (EOS) pretreatment is one of the most efficient methods for boosting biomass saccharification as it can achieve an efficient fractionation of three major constituents in lignocellulose. However, lignin repolymerization often occurs in acid EOS pretreatment, which impairs subsequent enzymatic hydrolysis. This study investigated acid EOS pretreatment assisted by carbocation scavenger (2-naphthol, 2-naphthol-7-sulfonate, mannitol and syringic acid) to improve biomass fractionation, coproduction of fermentable sugars and lignin adsorbents. In addition, surface barrier effect of lignin on cellulose hydrolysis was isolated from unproductive binding effect of lignin, and the analyses of surface chemistry, surface morphology and surface area were carried out to reveal the lignin inhibition mitigating effect of various additives. Four different additives all helped mitigate lignin inhibition on cellulose hydrolysis in particular diminishing surface barrier effect, among which 2-naphthol-7-sulfonate showed the best performance in improving pretreatment efficacy, while mannitol and syringic acid could serve as novel green additives. Through the addition of 2-naphthol-7-sulfonate, selective lignin removal was increased up to 76%, while cellulose hydrolysis yield was improved by 85%. As a result, 35.78 kg cellulose and 16.63 kg hemicellulose from 100 kg poplar could be released and recovered as fermentable sugars, corresponding to a sugar yield of 78%. Moreover, 22.56 kg ethanol organosolv lignin and 17.53 kg enzymatic hydrolysis residue could be recovered as lignin adsorbents for textile dye removal, with the adsorption capacities of 45.87 and 103.09 mg g−1, respectively. Results in this work indicated proper additives could give rise to the form of less repolymerized surface lignin, which would decrease the unproductive binding of cellulase enzymes to surface lignin. Besides, the supplementation of additives (NS, MT and SA) resulted in a simultaneously increased surface area and decreased lignin coverage. All these factors contributed to the diminished surface barrier effect of lignin, thereby improving the ease of enzymatic hydrolysis of cellulose. The biorefinery process based on acidic EOS pretreatment assisted by carbocation scavenger was proved to enable the coproduction of fermentable sugars and lignin adsorbents, allowing the holistic utilization of lignocellulosic biomass for a sustainable biorefinery.

中文翻译：

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碳正离子清除剂辅助有机溶剂预处理减轻木质素表面阻隔效应提高生物质糖化利用

乙醇有机溶剂 (EOS) 预处理是促进生物质糖化的最有效方法之一，因为它可以实现木质纤维素中三种主要成分的有效分馏。然而，木质素再聚合经常发生在酸性 EOS 预处理中，这会损害随后的酶水解。本研究调查了由碳正离子清除剂（2-萘酚、2-萘酚-7-磺酸盐、甘露醇和丁香酸）辅助的酸性 EOS 预处理，以改善生物质分馏、可发酵糖和木质素吸附剂的联合生产。此外，木质素对纤维素水解的表面屏障作用与木质素的非生产性结合作用分离，并进行了表面化学、表面形貌和表面积的分析，以揭示各种添加剂的木质素抑制缓解作用。四种不同的添加剂都有助于减轻木质素对纤维素水解的抑制作用，尤其是降低表面屏障作用，其中 2-萘酚-7-磺酸盐在提高预处理效果方面表现最佳，而甘露醇和丁香酸可作为新型绿色添加剂。通过添加2-萘酚-7-磺酸盐，选择性木质素去除率提高了76%，纤维素水解产率提高了85%。结果，100 公斤杨树的 35.78 公斤纤维素和 16.63 公斤半纤维素可以作为可发酵糖释放和回收，对应的糖收率为 78%。此外，可以回收 22.56 kg 乙醇有机溶剂木质素和 17.53 kg 酶解残留物作为木质素吸附剂用于去除纺织品染料，吸附容量分别为 45.87 和 103.09 mg g-1。这项工作的结果表明，适当的添加剂可以产生较少再聚合的表面木质素的形式，这将减少纤维素酶与表面木质素的非生产性结合。此外，添加添加剂（NS、MT 和 SA）导致表面积增加和木质素覆盖率降低。所有这些因素都导致木质素的表面屏障作用减弱，从而提高了纤维素酶水解的容易程度。事实证明，基于酸性 EOS 预处理和碳阳离子清除剂辅助的生物精炼工艺能够共同生产可发酵糖和木质素吸附剂，从而实现木质纤维素生物质的整体利用，以实现可持续的生物精炼。添加剂（NS、MT 和 SA）的补充同时导致表面积增加和木质素覆盖率降低。所有这些因素都导致木质素的表面屏障作用减弱，从而提高了纤维素酶水解的容易程度。事实证明，基于酸性 EOS 预处理和碳阳离子清除剂辅助的生物精炼工艺能够共同生产可发酵糖和木质素吸附剂，从而实现木质纤维素生物质的整体利用，以实现可持续的生物精炼。添加剂（NS、MT 和 SA）的补充同时导致表面积增加和木质素覆盖率降低。所有这些因素都导致木质素的表面屏障作用减弱，从而提高了纤维素酶水解的容易程度。事实证明，基于酸性 EOS 预处理和碳阳离子清除剂辅助的生物精炼工艺能够共同生产可发酵糖和木质素吸附剂，从而实现木质纤维素生物质的整体利用，以实现可持续的生物精炼。