Solid waste-derived solar desalination devices: Enhanced efficiency in water vapor generation and diffusion

Water scarcity and waste pollution are serious global challenges due to the rapid development of the global economy and population growth. A win–win strategy to address the water crisis and reduce pollution is to use waste materials as low-carbon and eco-friendly photothermal materials for solar-driven desalination. Steel slag, an abundant industrial waste product, has excellent thermal conductivity. Enhancing its light absorption and hydrophilicity could enable the creation of efficient and economical solar seawater desalination devices. In this study, our research introduces a 3D desalination device using this modified slag, achieving a consistent evaporation rate fluctuating around 29 kg m^-2h⁻¹ at 4 m s⁻¹ wind speed for five days. This breakthrough can be attributed to the excellent light-to-heat conversion of the modified steel slag, coupled with the synergistic interaction between the porous evaporator and wind, culminating in efficient steam evaporation and diffusion. Life Cycle Analysis (LCA) reveals that the carbon emissions of the modified steel slag for desalinating each ton of seawater are only 2.20 kg CO₂-eq, indicating superior prospects for carbon reduction compared to the reverse osmosis (RO) and Multi-Stage Flash Desalination (MSF) processes.