One-pot lignin extraction and modification in γ-valerolactone from steam explosion pre-treated lignocellulosic biomass

A one-pot route to extract and chemically modify lignin from a pre-treated Phragmites australis lignocellulosic biomass is proposed herein. The lignocellulosic biomass was first pre-treated through steam explosion at two different severity factors. Lignin was then extracted from the steam-exploded biomasses through a microwave-assisted organosolv extraction method, solely using γ-valerolactone as solvent. The most severe steam explosion condition yielded a delignification of 78%. Morphological analysis, spectroscopic investigation and thermal characterization showed that essentially pure lignin was extracted through this process. Lignin was then chemically modified in the γ-valerolactone extraction solution, through acetylation and Mannich condensation. This work provides proof-of-evidence that pure lignin can be solvent-extracted in high yields from a pre-treated biomass without the addition of any further chemicals and successfully modified in a one-pot route through a cleaner process. The modified lignin could be used as building block for the development of novel bio-based polymer materials.