(329e) Use of Biorenewable Alcohols in the Production of Lignin for High-Value Applications

Lignin has been explored as an alternative to synthetic polymers for various applications ranging from additives for asphalt, thermosets and thermoplastics to hydrogels for drug delivery. Intrinsic lignin properties, such as UV-absorption, radical-quenching, and antimicrobial properties, offer performance benefits to these materials. In addition, low-molecular weight aromatic and phenolic compounds produced from lignin may be used to replace fossil-carbon chemicals. However, inconsistent physicochemical properties and contaminants, such as carbohydrates and inorganics, along with a more condensed nature of technical lignins in comparison to that of lignin in situ are notoriously recognized as obstacles hindering broader use of lignin in high-value applications. This study aims to explore lignins produced after organosolv delignification conducted on both aspen and hydrothermally pretreated aspen using select biorenewable alcohols, specifically: low-boiling point alcohol, ethanol, and high-boiling-point alcohols, ethylene glycol, propylene glycol, 1,4-butanediol, and tetrahydrofurfuryl alcohol. These alcohols are selected based on their solubility parameters placing them relatively close to lignin in the Hansen space. Aspen lignins recovered from organosolv liquors are thoroughly characterized and compared to aspen MWL, and commercially available hardwood lignins, Alcell and kraft. Our goal is to assess the ability of these alcohols, applied individually or in conjunction with hydrothermal pretreatment, to selectively remove lignin from aspenwood chips and, produce lignin of improved properties, including purity and preserved chemical structure.