Waste PU-derived PDMS/ZIF-8/bentonite composite sponge for reusable oil sorption

Abstract

Rapid urbanization and population growth have intensified oil pollution, highlighting the need for efficient, selective, and multifunctional oil sorbents. In this study, a cost-effective hydrophobic composite was developed from waste polyurethane (PU) sponge with a durable 3D macroporous structure. The sponge was modified via dip-coating with zeolitic imidazolate framework (ZIF-8), bentonite, and polydimethylsiloxane (PDMS) to enhance hydrophobicity. The resulting PDMS/ZIF-8/bentonite-incorporated PU (ZBPU) sponge was characterized using powder X-ray Diffraction, Fourier Transform Infrared spectroscopy, and Scanning Electron Microscopy analyses. Contact angle measurements confirmed the hydrophobicity for the prepared ZBPU-3 sponge, indicating its suitability for oil separation applications. Sorption performance was tested with canola oil, methylene blue dye, and non-aqueous phase liquids (chloroform, toluene, xylene, benzene). ZBPU-3 exhibited an oil sorption capacity of 0.97 g/cm3, about twice that of pristine PU, and maintained effective performance for up to five sorption–desorption cycles, with oil uptake governed mainly by physical interactions. © 2026 The Authors