Magalhães Solange, Filipe Alexandra, Melro Elodie, Fernandes Catarina, Vitorino Carla, Alves Luís, Romano Anabela, Rasteiro Maria G, Medronho Bruno
Department of Chemical Engineering, CIEPQPF, University of Coimbra, Pólo II-R. Silvio Lima, 3030-790 Coimbra, Portugal.
Department of Chemistry, CQC, University of Coimbra, Rua Larga, 3004-535 Coimbra, Portugal.
Polymers (Basel). 2021 Mar 30;13(7):1090. doi: 10.3390/polym13071090.
Lignocellulosic biomass fractionation is typically performed using methods that are somehow harsh to the environment, such as in the case of kraft pulping. In recent years, the development of new sustainable and environmentally friendly alternatives has grown significantly. Among the developed systems, bio-based solvents emerge as promising alternatives for biomass processing. Therefore, in the present work, the bio-based and renewable chemicals, levulinic acid (LA) and formic acid (FA), were combined to fractionate lignocellulosic waste (i.e., maritime pine sawdust) and isolate lignin. Different parameters, such as LA:FA ratio, temperature, and extraction time, were optimized to boost the yield and purity of extracted lignin. The LA:FA ratio was found to be crucial regarding the superior lignin extraction from the waste biomass. Moreover, the increase in temperature and extraction time enhances the amount of extracted residue but compromises the lignin purity and reduces its molecular weight. The electron microscopy images revealed that biomass samples suffer significant structural and morphological changes, which further suggests the suitability of the newly developed bio-fractionation process. The same was concluded by the FTIR analysis, in which no remaining lignin was detected in the cellulose-rich fraction. Overall, the novel combination of bio-sourced FA and LA has shown to be a very promising system for lignin extraction with high purity from biomass waste, thus contributing to extend the opportunities of lignin manipulation and valorization into novel added-value biomaterials.
木质纤维素生物质分级通常采用对环境有一定危害的方法，例如硫酸盐制浆法。近年来，新型可持续且环保的替代方法有了显著发展。在已开发的体系中，生物基溶剂成为生物质加工的有前景的替代物。因此，在本研究中，将生物基可再生化学品乙酰丙酸（LA）和甲酸（FA）结合起来对木质纤维素废料（即海松锯末）进行分级并分离木质素。对不同参数，如LA:FA比例、温度和提取时间进行了优化，以提高提取木质素的产率和纯度。发现LA:FA比例对于从废弃生物质中高效提取木质素至关重要。此外，温度和提取时间的增加会提高提取残渣的量，但会损害木质素纯度并降低其分子量。电子显微镜图像显示生物质样品发生了显著的结构和形态变化，这进一步表明了新开发的生物分级工艺的适用性。傅里叶变换红外光谱（FTIR）分析也得出了相同结论，即在富含纤维素的部分未检测到残留木质素。总体而言，生物源FA和LA的新型组合已证明是一种非常有前景的从生物质废料中高纯度提取木质素的体系，从而有助于拓展木质素加工和增值为新型高附加值生物材料的机会。
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