Polyanionic Electrolyte Ionization Desalination Empowers Continuous Solar Evaporation Performance

Abstract

Solar evaporation contributes to sustainable and environmentally friendly production of fresh water from seawater and wastewater. However, poor salt resistance and high degree of corrosion of traditional evaporators in brine make their implementation in real applications scarce. To overcome such deficiency, a polyanionic electrolyte functionalization strategy empowering excellent uniform desalination performance over extended periods of time is exploited. This 3D superhydrophilic graphene oxide solar evaporator design ensures stable water supply by the enhanced self-driving liquid capillarity and absorption at the evaporation interface as well as efficient vapor diffusion. Meanwhile, the polyanionic electrolyte functionalization implemented via layer-by-layer static deposition of polystyrene sodium sulfonate effectively regulates/minimizes the flux of salt ions by exploiting the Donnan equilibrium effect, which eventually hinders local salt crystallization during long-term operation. Stable evaporation rates in line with the literature of up to 1.68 kg m−2 h−1 are achieved for up to 10 days in brine (15‰ salinity) and for up to 3 days in seawater from Hangzhou Bay in the East China Sea (9‰ salinity); while, maintaining evaporation efficiencies of ≈90%. This work demonstrates the excellent benefits of polyanionic electrolyte functionalization as salt resistance strategy for the development of high-performance solar powered seawater desalination technology and others.