Highly efficient three-dimensional solar evaporator for high salinity desalination by localized crystallization

Area of Science:

• Materials Science
• Environmental Science
• Chemical Engineering

Background:

• Solar-driven water evaporation offers a sustainable approach to water purification and desalination.
• High salt concentrations and accumulation impede the efficiency of conventional solar evaporators.
• Existing methods struggle with maintaining performance under varying salinity levels.

Purpose of the Study:

• To develop an energy reutilizing strategy for enhanced solar water evaporation using a bio-mimetic 3D structure.
• To address the challenges of salt accumulation and concentration in solar desalination.
• To achieve high water evaporation rates and energy efficiency, even with high salinity feed water.

Main Methods:

• Fabrication of a bio-mimetic 3D structure designed to create a non-uniform water film and temperature gradient.
• Utilizing the Marangoni effect for energy reutilization and localized salt crystallization.
• Testing the system with natural seawater under one sun illumination in a closed system.

Main Results:

• Achieved a solar-driven water evaporation rate of 2.63 kg m⁻² h⁻¹.
• Demonstrated high energy efficiency exceeding 96% under one sun illumination.
• Successfully operated at high salinity (25 wt% NaCl) with a water collecting rate of 1.72 kg m⁻² h⁻¹.
• Observed localized salt crystallization that was easily removed, with no negative impact on performance due to salt accumulation.

Conclusions:

• The proposed bio-mimetic 3D structure effectively utilizes input energy through the Marangoni effect for efficient solar water evaporation.
• The strategy overcomes salt accumulation issues, enabling sustained high performance in desalination of high-salinity water.
• The system shows significant potential for practical and sustainable applications in water purification and desalination.