Multiphase solar evaporator for localized salt harvesting and in-depth water purification

Solar-driven interfacial evaporation (SIE) has been receiving more and more attention on the stage called “Sustainable Development”. However, pursuing a rational coexistence of steady-state evaporation, endogenous resource recovery, and water decontamination in solar evaporators is still a great challenge. To address this problem, a one-dimensional water transport pathway chitosan-based multiphase evaporator (OCHE) was fabricated for simultaneous Marangoni-driven salt mitigation and dye adsorption while solar vapor generation. Due to the efficient energy utilization and water supply, OCHE achieves a water evaporation rate of 1.767 kg m−2 h−1 with an energy efficiency of 96.87% under one sun illumination. More importantly, the 1D water pathway induces directional solute capillary convection and thermocapillary convection in evaporator when OCHE is working in high-salinity brine, leading to localized salt harvesting driven by Marangoni-driven liquid transport. Moreover, OCHE exhibits the good adsorption capacity for methylene blue (MB) and methyl orange (MO). This versatile multiphase evaporator provides a new insight into the design of next-generation eco-friendly, salt-resistant, and in-depth water purification solar evaporators. [Display omitted] •Simultaneous salt mineral recovery and dye adsorption during solar evaporation.•Octahedral nanoporous carbon with excellent photothermal property is developed.•Optimized heat transfer and Marangoni mass transfer due to the special structure.•Good decontamination capability of mixed/complex wastewater.