Chen Jiachuan, Dong Jiran, Yang Guihua, He Ming, Xu Feng, Fatehi Pedram
1State Key Laboratory of Bio-based Materials and Green Papermaking, Qilu University of Technology (Shandong Academy of Sciences), Jinan, 250353 Shandong China.
2Green Processes Research Centre and Department of Chemical Engineering, Lakehead University, Thunder Bay, ON P7B 5E1 Canada.
Biotechnol Biofuels. 2018 Dec 21;11:337. doi: 10.1186/s13068-018-1336-0. eCollection 2018.
In the kraft-based dissolving pulp production process, pre-hydrolysis liquor (PHL) is produced, which contains hemicelluloses, lignin, furfural and acetic acid. PHL is currently burned in the recovery boiler of the kraft pulping process, but it can be utilized for the generation of high-valued products, such as xylitol and xylanase, via fermentation processes. However, some PHL constituents, e.g., furfural and lignin, are contaminants for fermentation processes and they must be eliminated for production of value-added products.
In this work, a process is introduced for removing contaminants of PHL. Ca(OH) treatment is the first step of this process, which removed 41.2% of lignin and negligible amount of sugars. In this step, a notable increase in the concentration of acetic acid was achieved (ranging from 6.2 to 11.7 g/L). In the second step, the implementation of adsorption using activated carbon (AC) at 1 wt% dosage led to additional 32% lignin and 5.9% xylosugar removals. In addition, laccase assisted activated carbon treatment led to further removal of lignin via accelerating lignin polymerization and adsorption on AC (i.e., removal from PHL). Overall, 90.7% of lignin, 100% of furfural, 5.7% of xylose, and 12% of xylan were removed from PHL, while the concentration of acetic acid became twofolds in the PHL.
This study reports an attractive process for purifying sugars and acetic acid of PHL. This process may be implemented for producing sugar-based value-added products from PHL. It also discusses the mechanism of Ca(OH) treatment, AC adsorption and laccase assisted activated carbon treatment for lignin removal.
在硫酸盐法溶解浆生产过程中会产生预水解液（PHL），其中含有半纤维素、木质素、糠醛和乙酸。目前，预水解液在硫酸盐制浆过程的回收锅炉中燃烧，但它可通过发酵工艺用于生产木糖醇和木聚糖酶等高价值产品。然而，预水解液中的一些成分，如糠醛和木质素，是发酵过程的污染物，为了生产增值产品，必须将它们去除。
在这项工作中，引入了一种去除预水解液污染物的工艺。氢氧化钙（Ca(OH)）处理是该工艺的第一步，去除了41.2%的木质素，糖的去除量可忽略不计。在这一步中，乙酸浓度显著增加（范围为6.2至11.7 g/L）。第二步，使用1 wt%剂量的活性炭（AC）进行吸附，额外去除了32%的木质素和5.9%的木糖。此外，漆酶辅助活性炭处理通过加速木质素聚合和在活性炭上的吸附（即从预水解液中去除），进一步去除了木质素。总体而言，预水解液中90.7%的木质素、100%的糠醛、5.7%的木糖和12%的木聚糖被去除，而预水解液中乙酸的浓度变为原来的两倍。
本研究报道了一种用于纯化预水解液中糖和乙酸的有吸引力的工艺。该工艺可用于从预水解液生产糖基增值产品。它还讨论了氢氧化钙处理、活性炭吸附和漆酶辅助活性炭处理去除木质素的机制。
