A multiscale transport model for non-classical nanochannel electroosmosis

Area of Science:

• Nanoscience and Surface Chemistry
• Fluid Dynamics
• Physical Chemistry

Background:

• Classical electroosmotic flow (EOF) models fail to predict velocity profiles in nanoscale channels with high surface charge.
• Non-classical charge distributions, including charge inversion and reduced counter-ion mobility, significantly impact interfacial phenomena.
• Interfacial electrohydrodynamics require advanced models to account for local viscosity changes.

Purpose of the Study:

• To develop a multiscale model for electroosmotic flow (EOF) in nanoscale channels with high surface charge liquid-solid interfaces.
• To explain the departure of EOF velocity profiles from classical predictions.
• To incorporate non-classical charge distributions and local viscosity enhancement into the EOF model.

Main Methods:

• Development of a multiscale model incorporating non-classical charge distribution and local viscosity.
• Application of Fuoss-Onsager theory and Hubbard-Onsager dielectric friction theory for local viscosity.
• Utilizing a generalized Langevin equation framework to calculate interfacial friction coefficients.
• Comparison of model predictions with molecular dynamics simulation results.

Main Results:

• The model explains anomalous EOF velocity profiles, including charge inversion and reduced counter-ion mobility.
• Local solvent viscosity enhancement is effectively modeled, impacting EOF.
• The model shows good agreement with molecular dynamics simulations for various transport phenomena, including EOF reversal.

Conclusions:

• The proposed multiscale model accurately describes electroosmotic flow in nanoscale channels with high surface charge.
• The model successfully captures anomalous transport phenomena like EOF reversal by accounting for interfacial effects.
• This work provides a robust framework for understanding and predicting EOF in confined systems.