Fe3O4 nanoparticles based dual network microporous hydrogel evaporator for efficient solar water purification

To alleviate the pressures of water and energy shortages amid rapid economic and social development, seawater desalination and wastewater purification have emerged as crucial research areas. The innovative solar interfacial evaporation technology for seawater desalination has garnered significant attention due to its clean and non-polluting characteristics. However, this technology faces the challenge of achieving a balance between high evaporation rates and robust mechanical properties in the evaporator. Therefore, we designed a dual-network hydrogel evaporator. This evaporator exhibits an average absorption rate of 98.80% across the ultraviolet, visible, and near-infrared regions, covering a broad wavelength range of 250 to 2500 nm. Thanks to its excellent light absorption properties, the evaporator maintains a stable evaporation rate of approximately 3 kg·m⁻²·h⁻¹ under one solar intensity, with an efficiency of up to 98.57%. In practical seawater tests, the concentrations of conventional salt ions in the purified water were found to be 2-3 orders of magnitude lower than the initial levels, all meeting the WHO drinking water standards. This study is expected to open new avenues for solar water purification in complex environments.