Effect of charge inversion on nanoconfined flow of multivalent ionic solutions

Area of Science:

• Nanofluidics
• Physical Chemistry
• Materials Science

Background:

• Understanding fluid dynamics in nanoconfined electrolytes is crucial for designing efficient nanofluidic devices.
• Interfacial phenomena, like charge inversion (CI), significantly alter transport properties in nanoconduits due to the electrical double layer's prominence.

Purpose of the Study:

• To investigate the structure and dynamics of aqueous multivalent electrolyte solutions in silica nanoconfinement.
• To reveal the influence of charge inversion (CI) on nanoconfined fluid transport and interfacial hydrodynamic properties.

Main Methods:

• All-atom molecular dynamics simulations were performed for over 100 ns.
• Simulations focused on aqueous solutions of sodium, magnesium, and aluminum chlorides in slit-shaped silica channels.

Main Results:

• Interfacial viscosity is directly related to the concentration and valence of counter-ions.
• Higher charge inversion (CI) correlates with an augmented viscosity layer at the channel wall.
• Increased thickness of this high-viscosity interfacial layer results in lower flow rates and higher friction coefficients.

Conclusions:

• Charge inversion (CI) in nanoconfined electrolytes significantly impacts fluid transport by increasing interfacial viscosity.
• The findings provide insights into the behavior of multivalent ions in nanofluidic systems and their effect on device performance.