A superhydrophobic photothermal carbon black-coated waste face mask for efficient water desalination

Low-cost and efficient interface evaporation technology based on solar energy has attracted much attention in seawater desalination, but is still challenging. In this study, a novel interface evaporator was constructed by brushing paste containing 1H,1H,2H,2H-perfluorodecyltriethoxysilane (FAS) modified carbon black (CB) nanoparticles and polyvinylidene fluoride (PVDF) on a pre-cleaned waste mask to develop the superhydrophobic photothermal layer, with cellulose non-woven fabric as the water supply layer and polystyrene foam as the insulation layer. Benefitting from the excellent light absorption capability of CB nanoparticles in the photothermal layer, the surface temperature of the evaporator increased up to 105 °C within 140 s with an evaporation rate of 1.58 kg m−2 h−1, and the photothermal conversion efficiency reached 94.3% under 1 kW m−2 of solar irradiation. The evaporator has shown excellent potential for long-term seawater desalination due to the use of FAS-modified CB nanoparticles, which create surface roughness, and hydrophobic PVDF adhesive, which helps in film formation. As a result, the evaporator has demonstrated significantly low heat loss, making it highly suitable for practical applications. This study demonstrates an economical and efficient solution in seawater desalination, wastewater treatment, and hydropower cogeneration.