Efficient Mild Organosolv Lignin Extraction in a Flow-Through Setup Yielding Lignin with High ?-O-4 Content.

ABSTRACT: Current lignin fractionation methods use harsh conditions that alter the native lignin structure, resulting in a recalcitrant material which is undesired for downstream processing. Milder fractionation processes allow for the isolation of lignins that are high in ?-aryl ether (?-O-4) content, however, at reduced extraction efficiency. The development of improved lignin extraction methods using mild conditions is therefore desired. For this reason, a flow-through setup for mild ethanosolv extraction (120 °C) was developed. The influence of acid concentration, ethanol/water ratio, and the use of other linear alcohol co-solvents on the delignification efficiency and the ?-O-4 content were evaluated. With walnut shells as model feedstock, extraction efficiencies of over 55% were achieved, yielding lignin with a good structural quality in terms of ?-O-4 linking motifs (typically over 60 per 100 aromatic units). For example, lignin containing 66 ?-O-4 linking motifs was obtained with an 80:20 n-propanol/water ratio, 0.18 M H₂SO₄ with overall a good extraction efficiency of 57% after 5 hours. The majority of the lignin was extracted in the first 2 hours and this lignin showed the best structural quality. Compared to batch extractions, both higher lignin extraction efficiency and higher ?-O-4 content were obtained using the flow setup.

SUBMITTER: Zijlstra DS 

PROVIDER: S-EPMC6960700 | biostudies-literature | 2019 Nov

REPOSITORIES: biostudies-literature