Recent advances in waste-derived sorbents for oil sorption and oil–water separation: progress and future prospects

Oil spills and industrial wastewater discharges pose significant threats to aquatic ecosystems and public health. Sorption-based technologies offer a promising approach for oil sorption and oil–water separation because of their low cost, simple operation, and broad availability of suitable raw materials. In recent years, waste-derived materials, including biomass residues, waste plastics, and industrial byproducts, have attracted increasing attention as sustainable sorbent precursors. This review provides a critical overview of recent advances in the fabrication, modification, and application of waste-derived sorbents for oil sorption and oil–water separation. Emphasis is placed on biomass-based materials, including biochar, activated carbon, aerogels, and carbon aerogels, as both primary sorbents and functional modifiers for improving commercial sorbents. Waste plastic- and industrial waste-derived sorbents are also summarized. Beyond material classification, this review discusses key sorption mechanisms, including wettability-controlled selectivity, capillary-driven oil uptake and pore filling, and oil droplet capture in sorption-assisted emulsion treatment. The morphology-dependent performance of powders/granules, foams/sponges, and aerogels/carbon aerogels is further compared in terms of recovery, regeneration, scalability, and limitations. Integrated strategies combining sorption with biodegradation, magnetic recovery, and demulsification–biosorption are also reviewed. Key challenges remain, including insufficient mechanical durability, limited regeneration efficiency, difficult post-use recovery, and scale-up barriers. Future studies should prioritize scalable fabrication, standardized performance metrics, practical regeneration and disposal strategies, and life-cycle and economic assessments.