Mechanochemical upcycling of pyrolyzed cork waste into biocompatible superhydrophobic PDMS sponges for passive oil–water separation

Oil spill pollution and industrial oily wastewater require remediation materials that combine high separation efficiency, mechanical durability, and environmental safety. Here, we report a solvent-free fabrication route for porous pyrolyzed cork-polydimethylsiloxane (pCork-PDMS) composite sponges based on cork-waste pyrolysis, mechanochemical activation processing, NaCl hard templating, and microwave-assisted curing. The optimized composite exhibits superhydrophobic/superoleophilic behavior with a water contact angle (WCA) of 151.7 ± 2.7° and enables passive oil-water separation with ∼99% efficiency for both floating and submerged oils. The sponge retained its sorption capacity over 100 sorption-squeezing cycles and maintained mechanical stability under repeated compression. Performance validation in harsh conditions and real seawater confirms operational robustness under realistic environmental conditions. In vitro cytotoxicity assays under both direct and indirect exposure using HaCaT keratinocytes and OECM-1 epithelial cells revealed no significant acute cytotoxic effects under the tested conditions, supporting the preliminary safety assessment of these biomass-derived sorbents for oil-water remediation.