Structural Features of Cork Dioxane Lignin from Quercus suber L

Area of Science:

• Biomass valorization
• Lignin chemistry
• Plant cell wall structure

Background:

• Cork (Quercus suber L.) is a renewable resource with a complex cell wall structure.
• Lignin, a major component, influences cork's properties and potential applications.
• Understanding cork lignin's detailed structure is crucial for its effective utilization.

Purpose of the Study:

• To isolate and characterize dioxane lignin from cork.
• To determine the S:G:H unit composition and identify specific linkages.
• To assess the abundance of various structural motifs and side chains.

Main Methods:

• Modified acidolytic procedure for lignin isolation.
• Permanganate oxidation, Py-GC-MS, NMR (liquid- and solid-state), and FTIR spectroscopy for structural analysis.
• Size exclusion chromatography (SEC) for molecular weight determination.

Main Results:

• Cork lignin is mainly of syringyl (S)/guaiacyl (G) type (S:G:H ratio 23:72:5).
• Ether bonds, particularly β-O-4' (38 mol %) and 4-O-5' (5 mol %), are the most abundant linkages.
• Ferulates were the sole cinnamic structures identified.

Conclusions:

• Cork lignin exhibits a distinct S/G composition with prevalent ether linkages.
• The structural insights facilitate exploring cork lignin's potential in material science and biorefining.
• Further research can optimize extraction and modification for targeted applications.