Dual-network hydrogel-coated 3D melamine foam for ultra-efficient solar-driven desalination

Solar-driven interfacial evaporation (SIE) is an innovative and highly effective water treatment method that employs photothermal materials to absorb solar energy and convert it into heat. By concentrating the heat at the water–air interface, SIE avoids the necessity of heating the entire body of water, significantly reducing thermal losses. In this study, we developed a composite material using polyvinyl alcohol (PVA) and sulfobetaine methacrylate (PSBMA) as the framework. And tannic acid (TA), as physical crosslinking, forms more hydrogen bonds with PSBMA and PVA. The coordination interaction between TA and Fe³ ⁺ facilitates the deposition of Fe³ ⁺ on the composite surface, thereby enhancing its light absorption properties. When combined with melamine foam (MF), the composite retains its three-dimensional interconnected structure and exhibits efficient water transport capabilities. When exposed to one-sun irradiation, the composite achieves a light absorption efficiency of 97.6 %, coupled with an evaporation rate of 4.31 kg·m⁻²·h⁻¹ . Additionally, it shows excellent solar desalination capabilities and maintains long-term stability in saline water solutions with concentrations varying from 3.5 to 20 wt%. This study provides an effective solution for addressing freshwater scarcity and wastewater treatment issues.