Conversion of skin collagen fibrous material waste to an oil sorbent with pH-responsive switchable wettability for high-efficiency separation of oil/water emulsions

Collagen fibrous material waste is an undervalued sustainable resource with many potential applications. Herein, a three-dimensional collagen fiber matrix (CFM), derived from skin collagen fiber waste generated in the leather industry, was modified by pH-responsive copolymer P(MAA-co-GMA) terminated with dodecyl hydrocarbon chains via an in situ free radical polymerization. The functionalized CFM possesses an appropriate porous structure, and shows switchable hydrophobicity/hydrophilicity for different pH values. It displayed high separation efficiency (∼99.93 ± 0.03%) for separating surfactant-free oil-in-water emulsion (10 cycles) as well as surfactant-stabilized oil-in-water emulsion (3 cycles). More importantly, the functionalized CFM displayed excellent self-cleaning performance. In other words, the absorbed oil was released after treatment in basic aqueous medium. The attractive properties of the functionalized smart collagen fiber matrix make it an excellent prospect for potential application in oily emulsion treatment from the reusable resource and environmentally friendly perspectives.