Abstract

The present study demonstrates an effective alkaline protocol for the extraction of quality hemicellulose using NaOH and NH₄OH combination from sugarcane bagasse for the production of xylooligosaacharides (XOs). For achieving maximum recovery of hemicellulose, the statistical optimization technique was adapted, while considering alkali concentration and temperature, as important process parameters, for all of the alkaline tested protocols like individual or mixed alkalis. The comparative study exposed that mixed alkalis promoted higher recovery of hemicellulose (68% wt xylose), which is relatively higher (up to 1.3-times) than the individual alkali protocols, such that it contained predominantly the xylose (xyl/ara ratio was 3.94) in the form of xylan. In perception, the synergistic action of different alkalis (weak and strong bases) have strongly influenced the selective cleavage of lignin-carbohydrate linkages, thereby enabling the higher release of hemicellulose under the modest reaction conditions (10% alkali conc. and 120 °C). Moreover, the analytical characterization witnessed that it is composed of majorly xylose with less or no undesired residual biomass constituents, including lignin. Upon evaluating the resultant hemicelluloses for XOs production via acidic hydrolysis, the hemicellulose obtained through the mixed alkalis protocol exhibited exceptional, resulting in ~ 13% wt XOs yield with a high degree of polymerization (2–4 units); it is relatively ~ 2.8-times higher than the result of other hemicelluloses. In addition, the formation of gaseous ammonia during the reaction of the mixed alkalis could potentially contribute to the reduction of overall processing cost through recovery and reuse strategy during the large-scale XOs production.

Graphic Abstract

中文翻译：

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碱的协同作用提高了甘蔗渣中半纤维素的提取质量，以生产低聚木糖

摘要

本研究证明了使用NaOH和NH ₄提取优质半纤维素的有效碱性方案甘蔗渣中的OH组合，用于生产木糖木聚糖（XOs）。为实现半纤维素的最大回收率，对统计优化技术进行了调整，同时将碱浓度和温度作为重要的工艺参数，适用于所有经过碱测试的方案，例如单个或混合碱。对比研究表明，混合碱促进了半纤维素（68％wt木糖）的更高回收率，这比单独的碱方案相对更高（高达1.3倍），因此它主要包含木糖（木糖/芳烃比为3.94） ）的形式。在感知上，不同碱（弱碱和强碱）的协同作用强烈影响了木质素-碳水化合物键的选择性裂解，因此，在适度的反应条件下（浓度为10％的碱和120°C），半纤维素的释放量更高。此外，分析表征证明其主要由木糖组成，具有较少或没有不希望的残留生物量成分，包括木质素。在评估通过酸性水解产生的XO产生的半纤维素时，通过混合碱方案获得的半纤维素表现出优异的性能，在高聚合度下（2-4个单元）可产生约13％wt的XO。它比其他半纤维素的结果高约2.8倍。此外，在混合碱反应中形成气态氨，可能通过大规模XO生产中的回收和再利用策略来降低总体加工成本。

图形摘要