Advances and potential for the use of waste materials as sorbents in remediation of PFAS contaminated soil—A review

• Waste-based materials were evaluated as sorbents for PFAS immobilization in soil. • Several candidate sorbents show greater sorption capacities than activated carbon. • Biochar emerges as the most mature and promising candidate. • Long-term sorption studies in soil are needed to assess practical applicability. Per- and polyfluoroalkyl substances (PFAS) pose significant environmental and human hazards due their resistance towards natural degradation. Anthropogenic activities have resulted in worldwide spreading of PFAS, and soil remediation of PFAS is challenging due to its persistent and mobile nature. Amendment with commercial activated carbon (AC) of fossil origin is one of the preferred immobilization strategies for contaminated soil. However, waste-based sorbents may represent a greener alternative to AC. Here, we review the status and potential for the use of waste-based materials as PFAS sorbents in soil remediation. Key properties in the search of candidate materials are discussed, followed by an overview of potential sorbents. The materials reviewed are bark, protein-rich waste, chitosan, amine-modified waste, compost, biosolids, biochar produced from waste-based substrates, and a selection of industrial waste, notably bottom- and fly ash, char and slag. Performance and sorption behavior of these materials are compared for long- and short-chain PFAS, and their applicability is further discussed. Besides great sorption capacity and affinity, promising amendments combine high abundance, low cost, a potential for modification and low risk. Biochar emerges as the most mature and promising candidate of the materials reviewed. Other waste-based materials also show great PFAS sorption capacities, but their performances in soil have not been properly assessed. Besides sorption studies in environmentally relevant matrices, upscaling and long-term studies are needed to further examine the potential use of waste-based sorbents in remediation of PFAS contaminated soil.