Upcycling medical facemasks into macroporous sorbents for marine oil spill cleanup

With billions of medical facemasks discarded globally each year, their accumulation poses serious environmental and biohazard risks. In this regard, this study presents a sustainable upcycling strategy that uses a simple process-homogenization, lyophilization, and hot annealing-to transform discarded polypropylene (PP)-based medical facemasks into lightweight, reusable macroporous sorbents for marine oil spill cleanup. The resulting sorbents, including the melt-blown (MB) fabric layer, were tested against crude oils -light, medium, and heavy crude oils, as well as gasoline and diesel-demonstrating fast sorption kinetics and high uptake capacities: 6-43 g g⁻¹ for crude oils, 9-24 g g⁻¹ for diesel, and 7.5-15 g g⁻¹ for gasoline. For all sorbents and oil types, the sorption kinetics were accurately described by the pseudo-second-order model, with calculated sorption capacities closely matching the experimental values. The sorbents exhibited higher sorption performance with highly viscous oil, indicating that beyond surface adsorption, oil diffusion into the pores, capillary transport, and strong oil-sorbent adhesion collectively enhance uptake. The PP sorbents retained over 85% of their original efficiency after ten reuse cycles. Moreover, the sorbents proved effective in separating crude oil-in-water emulsions, demonstrating the potential of macroporous PP sorbents for cleaning up marine crude oil spills and for separating oil-in-water emulsions.