Sustainable solar-driven MXene/polyvinylidene fluoride composite nanofiber membrane for oil/saltwater separation and distillation in the complex environment

Abstract

The escalating environmental crises and water scarcity necessitate innovative water purification and marine oil spill recovery strategies. This study elucidates the potential of photothermal materials as a sustainable, effective strategy for oil/water separation and desalination in extreme conditions. Multifunctional photothermal polyvinylidene fluoride (PVDF) nanofiber membranes integrated with MXene (Ti3C2Tx) nanosheets were synthesized via electrospinning technique. These embedded nanosheets act as solar absorbers and energy converters. Thanks to the superior hydrophobicity and photothermal conversion efficiency, the MXene/PVDF nanofiber membranes exhibited an impressive oil flux of 16977.9 L·m−2·h−1 for hexane flux (gravity-driven) and 1018.7 L·m−2·h−1 for heavy mineral oil flux (~20 cmHg vacuum filtration, 1 sun illumination). Concurrently, the membranes achieved a heavy mineral oil/saltwater rejection ratio exceeding 99%. Importantly, they maintained stability and performance in harsh environments (acidic, alkaline, high-energy UV light). The hydrophobic PVDF nanofiber membrane effectively protected the embedded MXene nanosheets from oxidation. Notably under 1 sun illumination, the photothermal MXene/PVDF nanofiber membrane quickly reached a surface temperature of 101.2 °C, attaining an evaporation rate of 1.56 kg·m−2·h−1 within an hour. These results underscore the potential for an all-in-one solution that efficiently combines oil/water separation and desalination, offering a compelling response to marine oil spills.