Turning lignin waste into functional sorbents for environmental remediation

Lignin, an abundant renewable resource secondary to cellulose, offers significant potential for high-value utilization. This review focuses on transforming lignin into functional composites (e.g., porous carbons, hydrogels, aerogels, sponge, foam, membrane) via diverse modifications (sulfonation, pHenolic, amination, graft copolymerization, alkylation, esterification, oxidation). Simultaneously, an in-depth analysis was performed to elucidate the structure-property relationship between lignin's hierarchical architecture and the performance characteristics of composite materials. These materials demonstrate exceptional performance in wastewater treatment, including dye/heavy metal adsorption, organic separation, and oil-water emulsion breakdown. We critically evaluate preparation strategies, structural advantages, application challenges, and future research directions, highlighting lignin's role in sustainable pollution remediation.