Lignin Extraction from Various Biomass Sources: A Comprehensive Review of Characteristics, Applications, and Future Prospects

Various biomass resources generate significant byproducts, including lignin, an aromatic polymer known for its abundance, affordability, and functional diversity. Converting lignin into valuable products is essential for a sustainable circular economy. This review discusses the extraction and utilization of lignin from various biomass sources, addressing the different methodologies for its extraction, including physical, chemical, physiochemical, and biological pretreatment. Additionally, its potential applications in biofuels, chemicals, and polymers are explored. The importance of lignin's origin, chemical modifications, and physical characteristics in determining its suitability for different applications is emphasized. This review explores various pretreatment techniques, emphasizing deep eutectic solvent pretreatment for its efficiency in lignin dissolution and depolymerization into valuable aromatic compounds. The review discusses the applications of these advanced pretreatment technologies that can significantly contribute to the sustainable development of lignin applications in biofuels and biochemicals, reducing reliance on fossil fuels and promoting the utilization of renewable resources. Overall, this review is an overview of the lignin extraction processes used for diverse biomass sources, their efficiency, and their implications for downstream applications. It also highlights the versatility and adaptability of lignin extraction techniques across different biomass resources.