Synthetic textile upcycling to produce functional adsorbents: state-of-the-art, challenges and outlook

The use of waste materials as low-cost adsorbents for treating water pollutants offers many advantages as they contribute to reducing waste disposal costs and aiding sustainable resource management. Synthetic textile wastes pose environmental threats, hence their upcycling to adsorbents for treating water pollutants presents a good option for sustainability and circularity. The synthetic textiles are employed in their pristine, chemically functionalized, or morphologically tailored forms, including fiber felts, electrospun membranes, 3D-printed monoliths, and activated carbon (AC). This review critically examined up-to-date research, common target pollutants, performance and trends regarding the upcycling of synthetic textiles to produce functional adsorbents for water treatment. Generally, adsorption performance towards organic and inorganic pollutants including emerging contaminants is controlled by surface area/porosity, surface functionality/chemistry, morphology, crystallinity, wettability, and stability. For metals and dyes, performance depends almost entirely on functionalization, e.g., coatings, grafting, carbonization. For hydrocarbons and oils, hydrophobic pristine textiles already perform well, however, performance is further improved via surface functionalization. For emerging contaminants such as microplastics and PFAS, synthetic textiles are largely underutilized, with current evidence dominated by microplastic-vector studies and composite materials rather than purpose-designed textile-based adsorbents. Noteworthily, the upcycled adsorbents serve potentially lower-cost and more circular alternatives in location-specific applications, rather than universal replacements for AC or ion exchange resins. Consequently, synthetic textile-derived adsorbents are economically promising, however, rigorous cost analysis, regeneration, real wastewater systems, and scale-up operations remain a major missing piece and a clear priority for future research. Additionally, comprehensive leaching and chemical screening are required prior to deployment. Moreover, spent adsorbents and regeneration liquors must be managed through metal recovery, eluate treatment, or controlled destruction, consistent with for example, EU textile collection and EPR policies. Standardized testing should quantify hydraulic performance, breakthrough behavior, dynamic capacity, mass transfer, mechanical stability, material shedding, bed utilization, and regeneration durability to enable reliable adsorbent comparisons.