Solar-driven desalination using salt-rejecting plasmonic cellulose nanofiber membrane

Area of Science:

• Materials Science
• Renewable Energy
• Environmental Science

Background:

• Solar-driven steam generation offers a sustainable solution for water purification.
• Salt accumulation on photothermal materials impedes the long-term efficiency of solar desalination.

Purpose of the Study:

• To develop an efficient, salt-rejecting photothermal membrane for solar desalination.
• To address the challenge of salt scaling in solar steam generation.

Main Methods:

• Fabrication of plasmonic cellulose-based membranes (CMNF-NP) using gold/silver nanoparticles, cellulose nanofibers, and polyethyleneimine.
• Testing the water evaporation rate and solar-to-vapor conversion efficiency under 1-sun irradiation.
• Evaluating the membrane's performance and salt-rejecting capability with distilled water and 3.5 wt% brine over 10 hours.

Main Results:

• The CMNF-NP membrane achieved a water evaporation rate of 1.31 kg m⁻²h⁻¹ with 82.1% solar-to-vapor efficiency for distilled water.
• Comparable evaporation rates were maintained for brine, unlike filter paper counterparts that suffered from salt scaling.
• Efficient salt rejection was attributed to the membrane's compact structure and electrostatic repulsion from cellulose nanofibers and polyethyleneimine.

Conclusions:

• The developed CMNF-NP membrane demonstrates high efficiency and excellent salt-rejecting properties for solar desalination.
• The simple fabrication method allows for easy coating on various substrates, paving the way for practical applications.
• This technology offers a promising solution for sustainable water purification, overcoming the limitations of salt scaling.