Cabrera María Noel, Rossi Antonella, Guarino Juan Ignacio, Felissia Fernando Esteban, Area María Cristina
Engineering School, Chemical Engineering Institute/Forest Processes Engineering Group, Universidad de la República, Montevideo 11300, Uruguay.
Institute of Materials of Misiones, Pulp and Paper Program (PROCYP), Universidad Nacional de Misiones, Posadas 3300, Misiones, Argentina.
Polymers (Basel). 2025 Jun 6;17(12):1589. doi: 10.3390/polym17121589.
Alkaline treatment is well suited for extracting high-molecular-weight hemicelluloses, specifically hardwoods xylans, which, due to their polymer structure and chemical characteristics, enable the production of films with desirable mechanical, barrier, and optical properties for packaging applications. Despite its relevance, the optimization of antisolvent addition has received little attention in the literature. This study explores the use of eucalyptus industrial residue as feedstock, utilizing a statistical design to determine the optimal extraction conditions for hemicelluloses while minimizing the lignin content in the recovered liquor. The process uses alkali loads that are compatible with those in conventional Kraft pulp mills. Optimal extraction conditions involve a temperature of 105 °C, 16.7% NaOH charge, and 45 min at maximum temperature. The resulting liquor was subjected to ethanol precipitation under varying pH conditions (initial pH, 9, 7, 5, and 2) and different ethanol-to-liquor ratios (1:1 to 4:1). The acidification was performed using hydrochloric, sulfuric, and acetic acids. Ethanol served as the main antisolvent, while isopropyl alcohol and dioxane were tested for comparison. Results show that 2.3 ± 0.2% of xylans (based on oven-dry biomass) could be extracted, minimizing lignin content in the liquor. This value corresponds to the extraction of 15.6% of the xylans present in the raw material. The highest xylan precipitation yield (78%) was obtained at pH 7, using hydrochloric acid for pH adjustment and an ethanol-to-liquor ratio of 1:1. These findings provide valuable insight into optimizing hemicellulose recovery through antisolvent precipitation, contributing to more efficient biomass valorization strategies within lignocellulosic biorefineries.
碱性处理非常适合提取高分子量的半纤维素，特别是阔叶木聚糖，由于其聚合物结构和化学特性，能够生产出具有理想机械、阻隔和光学性能的薄膜，用于包装应用。尽管其具有相关性，但抗溶剂添加的优化在文献中很少受到关注。本研究探索使用桉木工业残渣作为原料，利用统计设计来确定半纤维素的最佳提取条件，同时尽量减少回收液中的木质素含量。该工艺使用的碱负荷与传统硫酸盐制浆厂的碱负荷兼容。最佳提取条件包括温度为105°C、NaOH用量为16.7%以及在最高温度下保持45分钟。将所得溶液在不同pH条件（初始pH为9、7、5和2）和不同乙醇与溶液比例（1:1至4:1）下进行乙醇沉淀。使用盐酸、硫酸和乙酸进行酸化。乙醇作为主要抗溶剂，同时测试了异丙醇和二氧六环以作比较。结果表明，可以提取2.3±0.2%的木聚糖（基于烘干生物质），使溶液中的木质素含量降至最低。该值相当于提取了原料中15.6%的木聚糖。在pH为7时，使用盐酸调节pH并乙醇与溶液比例为1:1时，获得了最高的木聚糖沉淀产率（78%）。这些发现为通过抗溶剂沉淀优化半纤维素回收提供了有价值的见解，有助于木质纤维素生物精炼厂采用更高效的生物质增值策略。
