High-Performance Janus Solar Evaporator for Salt-Resistant Desalination and Organic Pollutant Removal

Area of Science:

• Materials Science
• Chemical Engineering
• Environmental Science

Background:

• Interfacial solar steam generation (ISSG) is a promising technology for freshwater production.
• Current ISSG systems face challenges including inefficient thermal management, salt accumulation, and low evaporation rates.
• Addressing these limitations is crucial for practical applications in desalination and water purification.

Purpose of the Study:

• To develop a Janus-type solar evaporator with enhanced thermal localization and water transport capabilities.
• To improve evaporation rates and salt resistance for efficient solar steam generation.
• To demonstrate the potential of the evaporator for seawater desalination and industrial wastewater treatment.

Main Methods:

• Fabrication of a bilayer evaporator using a CNTs/PVDF composite membrane (top layer) and an SA hydrogel-encapsulated melamine sponge (bottom layer).
• Utilized an impregnation-drying method for membrane fabrication and in situ synthesis for the hydrogel substrate.
• Characterized the evaporator's performance under simulated solar irradiation (1 kW m^-2) with varying salinities.

Main Results:

• Achieved a high evaporation rate of 3.2 ± 0.12 kg m^-2 h^-1 and a photothermal conversion efficiency of 92.2 ± 2.34%.
• Demonstrated excellent salt resistance, maintaining an evaporation rate of 2.75 ± 0.15 kg m^-2 h^-1 at 25 wt % NaCl.
• The Janus structure effectively suppressed salt accumulation and improved thermal localization.

Conclusions:

• The developed three-dimensional Janus evaporator offers a cost-effective and scalable solution for efficient solar desalination.
• The device exhibits excellent operational stability and potential for treating high-salinity water and industrial wastewater.
• This work advances ISSG technology towards practical implementation for global freshwater security.