Asymmetric-Wettability Janus Sponge for Switchable Oil/Water Separation and Photocatalytic Remediation of...

The escalating issue of oil contamination and aqueous persistent pollutants necessitates advanced remediation materials. In this study, an asymmetric Janus sponge was synthesized using a synthetic BiOBr semiconductor to in situ grow CAU-17 metal-organic frameworks (MOFs) and serve as a Bi³⁺ donor. One side of the melamine sponge (MS) was functionalized with hydrophilic BiOBr/CAU-17, while the opposite side was modified with polydimethylsiloxane (PDMS) to achieve superhydrophobicity. This design resulted in a Janus sponge with contrasting wettability: the PDMS-coated side displayed a water contact angle exceeding 150.4°, attributed to low surface energy from interconnected 3D porous channels and hydrophobic PDMS carbon chains. This enabled selective oil adsorption (15-38 times its own weight) and >99% water separation efficiency. The BiOBr/CAU-17@MS interface demonstrated potent photocatalytic activity, degrading rhodamine B, methylene blue, and tetracycline hydrochloride with 97% efficiency under visible light, even at high pollutant concentrations (50 mg/L). These findings highlight the Janus sponge's dual functionality for simultaneous oil-water separation and degradation of organic contaminants, offering a promising solution for treating complex wastewater containing both oils and dissolved pollutants.