Surface charge-dependent hydrodynamic properties of an electroosmotic slip flow

2018 ◽  
Vol 20 (48) ◽  
pp. 30365-30375 ◽  
Author(s):  
Majid Rezaei ◽  
Ahmad Reza Azimian ◽  
Ahmad Reza Pishevar
Keyword(s):  
Surface Charge ◽  
Electroosmotic Flow ◽  
Slip Flow ◽  
Solid Surfaces ◽  
General View ◽  
Hydrodynamic Properties

The present paper provides a general view of the charge-dependent electroosmotic flow slippage over hydrophobic solid surfaces.

Thermodynamics of ideal polarizable interfaces

1996 ◽  
Author(s):  
Wolfgang Schmickler
Keyword(s):  
Surface Charge ◽  
Electrolyte Solution ◽  
Solid Surfaces ◽  
Liquid Electrode ◽  
Liquid Electrodes ◽  
Solid Electrodes ◽  
Liquid Surfaces

For liquid electrodes thermodynamics offers a precise way to determine the surface charge and the surface excesses of a species. This is one of the reasons why much of the early work in electrochemistry was performed on liquid electrodes, particularly on mercury - another reason is that it is easier to generate clean liquid surfaces than clean solid surfaces. With some caveats and modifications, thermodynamic relations can also be applied to solid surfaces. We will first consider the interface between a liquid electrode and an electrolyte solution, and turn to solid electrodes later.

scholarly journals Electroosmosis as a probe for electrostatic correlations

Soft Matter ◽  
2020 ◽  
Vol 16 (47) ◽  
pp. 10688-10696
Author(s):  
Ivan Palaia ◽  
Igor M. Telles ◽  
Alexandre P. dos Santos ◽  
Emmanuel Trizac
Keyword(s):  
Surface Charge ◽  
Electroosmotic Flow ◽  
Channel Surface ◽  
Electrostatic Coupling

Ionic correlations affect electroosmosis in planar salt-free channels. Electroosmotic flow can then be used as a calibrated measurement of electrostatic coupling and channel surface charge.

scholarly journals Anomalous Interfacial Structuring of a Non-Halogenated Ionic Liquid: Effect of Substrate and Temperature

2018 ◽  
Vol 2 (4) ◽  
pp. 60 ◽  
Author(s):  
Milad Radiom ◽  
Patricia Pedraz ◽  
Georgia Pilkington ◽  
Patrick Rohlmann ◽  
Sergei Glavatskih ◽  
...  
Keyword(s):  
Ionic Liquid ◽  
Surface Charge ◽  
Force Measurement ◽  
Surface Force ◽  
Solid Surfaces ◽  
Effect Of Temperature ◽  
Decay Length ◽  
Force Microscopy ◽  
Large Size ◽  
Atomic Force

We investigate the interfacial properties of the non-halogenated ionic liquid (IL), trihexyl(tetradecyl)phosphonium bis(mandelato)borate, [P6,6,6,14][BMB], in proximity to solid surfaces, by means of surface force measurement. The system consists of sharp atomic force microscopy (AFM) tips interacting with solid surfaces of mica, silica, and gold. We find that the force response has a monotonic form, from which a characteristic steric decay length can be extracted. The decay length is comparable with the size of the ions, suggesting that a layer is formed on the surface, but that it is diffuse. The long alkyl chains of the cation, the large size of the anion, as well as crowding of the cations at the surface of negatively charged mica, are all factors which are likely to oppose the interfacial stratification which has, hitherto, been considered a characteristic of ionic liquids. The variation in the decay length also reveals differences in the layer composition at different surfaces, which can be related to their surface charge. This, in turn, allows the conclusion that silica has a low surface charge in this aprotic ionic liquid. Furthermore, the effect of temperature has been investigated. Elevating the temperature to 40 °C causes negligible changes in the interaction. At 80 °C and 120 °C, we observe a layering artefact which precludes further analysis, and we present the underlying instrumental origin of this rather universal artefact.

scholarly journals Kinetics of Enzyme Attack on Substrates Covalently Attached to Solid Surfaces: Influence of Spacer Chain Length, Immobilized Substrate Surface Concentration and Surface Charge

Langmuir ◽  
2008 ◽  
Vol 24 (20) ◽  
pp. 11762-11769 ◽  
Author(s):  
Joseph Deere ◽  
Rui F. De Oliveira ◽  
Bartłomiej Tomaszewski ◽  
Sarah Millar ◽  
Antonia Lalaouni ◽  
...  
Keyword(s):  
Surface Charge ◽  
Chain Length ◽  
Substrate Surface ◽  
Surface Concentration ◽  
Solid Surfaces ◽  
Spacer Chain Length ◽  
Immobilized Substrate ◽  
Kinetics Of

Molecular Dynamics Simulation of Electroosmotic Flow in Nanotubes

2007 ◽  
Author(s):  
Yunfei Chen ◽  
Zhonghua Ni ◽  
Guiming Wang ◽  
Dongyan Xu ◽  
Deyu Li
Keyword(s):  
Molecular Dynamics ◽  
Surface Charge ◽  
Surface Charge Density ◽  
Electroosmotic Flow ◽  
Continuum Theory ◽  
Ion Distribution ◽  
Charge Inversion ◽  
Charge Densities ◽  
Simulation Results ◽  
The Continuum

The ion distribution and electroosmotic flow of sodium chloride solutions confined in cylindrical nanochannels with different surface charge densities are studied with molecular dynamics (MD). In order to obtain simulation results corresponding to more realistic situations, the MD simulation consists of two steps. The first step is used to equilibrate the system and obtain a more realistic ion distribution in the solution under different surface charge densities; and the second step is to apply an electrical field to drive the liquid and extract the electroosmotic flow information. Simulation results indicate that a higher surface-charge density corresponds to a higher peak of the counter ion concentration. Predictions based on the continuum theory were also calculated and compared with the molecular dynamics results. Even though the continuum theory cannot reflect the molecular nature of ions and water molecules, it is found that for low surface charge densities, the continuum theory can still give reasonable results if modified boundary conditions are applied. Charge inversion under high surface charge density has been predicted and observed recently, however, the simulation results do not indicate charge inversion even for a surface density as high as −0.34 C/m2. This might be due to the fact that we perform the MD simulations with monovalent ions, which have a tendency to suppress charge inversion, as demonstrated in the recent literature.

Thermal Effect on Electroosmotic Flow in a Slit Microchannel

2013 ◽  
Author(s):  
Yi Zhou ◽  
Chun Yang ◽  
Cunlu Zhao
Keyword(s):  
Boltzmann Equation ◽  
Charge Density ◽  
Surface Charge ◽  
Thermal Effect ◽  
Electroosmotic Flow ◽  
Stokes Equations ◽  
Ion Distribution ◽  
Temperature Dependent ◽  
Constant Potential ◽  
Constant Charge

Electroosmotic flow (EOF) in microfluidic systems is frequently subjected to thermal effect because of temperature-dependent material properties. Boltzmann equation is usually used to describe the ion distribution in EOF. This study will compare the ion distribution under the thermal effect with the Boltzmann distribution. Moreover, for thin electrical double layer (EDL), constant potential model always be used to simplify the calculation of EOF at constant charge. In this study, the thermal effects on EOF at both constant potential and constant charge are analyzed. In addition, as the surface charge density increases largely with higher temperature, in this study efforts are also made to address the thermal effect on EOF induced by the temperature-dependent charge density. In particular, a numerical model is presented for investigating the steady EOF under the thermal effect. The proposed model involves several coupled governing equations including the Nernst-Planck equations, the Poisson equation, the modified Navier-Stokes equations, and the energy equation. The simulation results show that the Boltzmann equation cannot fully describe the ionic concentration distributions under the large thermal effect when EDL overlap. Moreover, for thin EDL, the electroosmotic velocity under the thermal effect at constant potential is lower than that at constant charge, due to the negative electrothermal force at constant potential. Furthermore, it is revealed that the temperature-dependence of surface charge can significantly modify the characteristics of EOF.

Model Development for Fluid Structure Interaction in the Slip Regime

2010 ◽  
Author(s):  
Jennifer van Rij ◽  
Todd Harman ◽  
Tim Ameel
Keyword(s):  
Energy Exchange ◽  
Temperature Jump ◽  
Slip Flow ◽  
Model Development ◽  
Fluid Structure Interaction ◽  
Solid Surfaces ◽  
Fluid Structure ◽  
Structure Interaction ◽  
First Order ◽  
Slip Regime

While many microscale systems are subject to both rarefaction and fluid-structure-interaction (FSI) effects, most commercial algorithms cannot model both, if either, of these for general applications. This study modifies the momentum and thermal energy exchange models of an existing, continuum based, multifield, compressible, unsteady, Eulerian-Lagrangian FSI algorithm, such that the equivalent of first-order slip velocity and temperature jump boundary conditions are achieved at fluid-solid surfaces, which may move with time. Following the development and implementation of the slip flow momentum and energy exchange models, several basic configurations are considered and compared to established data to verify the resulting algorithm’s capabilities.

Surface charge mapping of solid surfaces in water by pulsed-force-mode atomic force microscopy

1998 ◽  
Vol 66 (7) ◽  
pp. S349-S352 ◽  
Author(s):  
T. Miyatani ◽  
S. Okamoto ◽  
A. Rosa ◽  
O. Marti ◽  
M. Fujihira
Keyword(s):  
Atomic Force Microscopy ◽  
Surface Charge ◽  
Solid Surfaces ◽  
Force Microscopy ◽  
Atomic Force ◽  
Force Mode ◽  
Mode Atomic Force Microscopy
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