Humidity-insensitive water evaporation from molecular complex fluids

Area of Science:

• Physical Chemistry
• Materials Science

Background:

• Solvent evaporation from concentrated solutions forms a solute layer at the interface.
• This layer influences evaporation rates, particularly in the long-time-scale (falling rate) period.

Purpose of the Study:

• To theoretically investigate water evaporation from concentrated supramolecular mixtures.
• To determine the influence of ambient humidity on evaporation rates in the falling rate period.

Main Methods:

• Numerical resolution of a one-dimensional model based on mass transport equations.
• Analytical solutions in limiting cases were used to validate findings.

Main Results:

• Evaporation rates in the falling rate period are often independent of ambient humidity for complex fluids.
• A sharp decrease in water chemical activity and a strong decrease in the mutual diffusion coefficient significantly reduce humidity dependence.

Conclusions:

• Concentrated solute layers and diffusion limitations dominate evaporation in the falling rate period.
• Strong concentration gradients effectively shield the evaporation process from external humidity variations.