Characterization of cottonseed hull lignin for valorizing it into value-added chemicals and materials

Cottonseed hulls (CSHs) emerge as a promising lignocellulosic feedstock for synthesizing high-value products through the biorefinery approach. However, scant attention has been devoted to a detailed characterization of their primary components, particularly the intricate lignin fraction. This study conducted a comprehensive compositional analysis of CSHs, primarily delving into the intricate characterization of lignin samples extracted via organosolv and alkaline methods. The investigation encompassed the fundamental lignin unit composition, inter-chemical linkages, molecular weight distribution, and functional group profile. Further analysis revealed that alkaline-extracted lignin possesses a higher abundance of low-molecular-weight lignin fragments and hydroxyl groups than organosolv-extracted lignin. This distinct characteristic renders alkaline lignin a favorable candidate for producing chemicals and functional materials via bioconversion and chemical modification. To demonstrate this, alkaline lignin was successfully valorized into cis, cis-muconate and white lignin material. This study provides valuable insights into the fundamental characteristics of CSH lignin, uncovering its potential for the synthesis of value-added chemicals and materials.