During the process of hot water extraction (HWE) of hardwoods, such as sugar maple and willow, about 10% of lignin is dissolved. HWE takes place in mild acid conditions (end pH of ~3.5) and temperatures of 160-170�C. Lignin hydrolysis reactions, including cleavage of benzyl ether bonds, take place in these conditions yielding lignin fragments of different molar masses (polydispersity of ~3). Their characterization is vital for exploration of opportunities to use lignin dissolved in HWE and expand the biorefinery product portfolio. In this study, lignin dissolved during HWE is fractionated by sequential extraction with solvents of increasing polarity to produce lignin fragments of uniform composition including molar mass distribution (MMD). The fractions are then characterized by standard lignin methods, including size exclusion chromatography (SEC) to determine MMD and polydispersity. Lignin of higher uniformity produced may be used in applications requiring high quality lignin, e.g. carbon fibers.

SEC studies of lignin extracted from hardwoods in hot water extraction

243rd National Meeting (2012)

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