Surface embedding enhancing interfacial photothermal effect of MXene/EP sponge for effective oil/water separation

The dramatically increasing demanding of crude oil requires effective production/recovery. Nonetheless, the high viscosity of crude oil hinders its recovery. Photothermal sponges show high efficiency on solar-thermal conversion, oil/water separation, crude oil recovery. However, coating/mixing photothermal agents with sponge suffers from the ease of peeling-off, high mixing content, reduction on mechanical elasticity, low solar-thermal conversion efficiency. Herein, photothermal superwetting MXene/Epoxy (MXene/EP) sponge was developed through embedding small amount of MXene at the sponge skeleton surface during mold transfer. Results showed that MXene was successfully embedded onto the skeleton of EP sponge and wave-like structure was formed. Embedding content of MXene increased from 0.33 w% to 1.0 w% caused the medium pore diameter and total pore area firstly increases and then decreases. This caused the oil/water separation flux dropped from 3092.15 L•m−2•h−2 to 1840.43 L•m−2•h−2. Embedding 0.33 w% MXene resulted the compressive stress decreased to 40.2 KPa comparing with intrinsic EP sponge and returned to its original state after 50 cycles of compressive test while the compressive stress sharply increased to 240 KPa with embedding 1.0 w% MXene. MXene/EP sponge can be rapidly heated up to 54.2 °C under 1.5 simulated sunlight with embedding 0.33 w% MXene at the skeleton surface. Such quick photothermal efficiency enables the crude oil penetrated the photothermal sponge within 80 s showing high efficiency on crude oil collection. This one-step fabrication of photothermal, superwetting and mechanical robust EP sponge showed great potential in practical oil/water separation.