Springtail-inspired omniphobic slippery membrane with nano-concave re-entrant structures for membrane distillation

Area of Science:

• Materials Science
• Surface Chemistry
• Chemical Engineering

Background:

• Membrane distillation (MD) technology faces limitations that omniphobic membranes can address.
• Existing fabrication methods for omniphobic membranes are often complex and costly.

Purpose of the Study:

• To develop a simple and facile method for fabricating omniphobic membranes.
• To mimic the surface morphology of springtails for enhanced membrane properties.
• To evaluate the performance of the fabricated omniphobic membrane in membrane distillation.

Main Methods:

• Electrospraying a polyvinylidene fluoride substrate with polystyrene beads to imitate springtail surface morphology.
• Controlling electrical traction (voltage) and air resistance (humidity) during electrospraying.
• Mimicking springtail lipid coating using a low-toxicity perfluoropolyether lubricant via dip-coating.
• Testing the omniphobic membrane's performance in membrane distillation (MD) with artificial seawater.

Main Results:

• Successful fabrication of omniphobic membranes with concave-shaped polystyrene beads.
• Achieved significant increase in membrane hydrophobicity, evidenced by rapid water bouncing (16.3 ms).
• Demonstrated stable 99.9% salt rejection rate in MD treatment of seawater with sodium dodecyl sulfate.

Conclusions:

• The bio-inspired electrospraying and dip-coating method offers a simple and effective route to omniphobic membranes.
• The developed omniphobic membranes show great potential for efficient desalination via membrane distillation.
• This approach overcomes key bottlenecks in current membrane distillation technology.