Photothermal nanocomposite membranes for direct solar membrane distillation

Efficient utilization of renewable energy for desalination is critical to solving the world's water scarcity issues. In this manuscript, we report a novel direct solar membrane distillation (MD) process that utilizes a photothermal nanoparticle coating to capture sunlight and convert it to heat at the membrane surface, providing the thermal driving force for the MD process. This approach overcomes the major limitation of temperature polarization encountered in conventional MD processes and significantly increases the energy efficiency of MD. Membranes coated with carbon black nanoparticles or SiO2/Au nanoshells showed an increase of up to 33.0% in distillate flux when irradiated with simulated sunlight at 1 sun unit in a bench scale direct contact membrane distillation system, while the salt rejection and liquid entry pressure remained unchanged. These results demonstrate the potential of photothermal membranes for direct solar MD.