Novel photothermal magnetic Janus membranes suitable for solar water desalination

Abstract Water scarcity is a critical global challenge, underscoring the urgent need for efficient and sustainable desalination technologies with minimal brine disposal. This study introduces a novel solar water desalination approach using photothermal magnetic Janus membranes. The magnetic filler in the membranes serves three main functions: it maintains buoyancy at the air/water interface, captures particles to reduce contamination risks, and alters salt deposition on the membrane. A comprehensive analysis was conducted, including water contact angle measurements, light absorbance testing, and evaporation rates under natural sunlight. Additional characterization techniques, such as atomic force microscopy, scanning electron microscopy, thermogravimetric analysis, differential scanning calorimeter, and Fourier transform infrared spectroscopy-attenuated total reflection, were applied to both blank and photothermal membranes. Properties like mechanical strength, thickness, porosity, and surface roughness were systematically analyzed. The photothermal membranes were evaluated using a floating solar-driven desalination prototype, thermally analyzed via thermal imaging. The results showed that the iron–nickel alloy filler achieved over 90% light absorption and enhanced evaporation rates by up to 170% compared to blank membranes. Thermal imaging confirmed significant heat retention at the water surface, leading to higher evaporation rates. These findings highlight the potential of photothermal magnetic Janus membranes as a promising solution for sustainable desalination to combat global water scarcity.