Surface Charge Densities of Two Actinide(IV) Oxides: UO2 and ThO2

2002 ◽  
Vol 256 (2) ◽  
pp. 256-261 ◽  
Author(s):  
Mattias Olsson ◽  
Anna-Maria Jakobsson ◽  
Yngve Albinsson
Keyword(s):  
Surface Charge ◽  
Charge Densities

The surface charge on manganese dioxides

Soil Research ◽  
1981 ◽  
Vol 19 (1) ◽  
pp. 41 ◽  
Author(s):  
RM McKenzie
Keyword(s):  
Theoretical Model ◽  
Surface Charge ◽  
Charge Densities

Surface charge was measured on four synthetic manganese dioxides. Charge densities on two cryptomelanes followed closely the values predicted by a theoretical model. Charge densities on two birnessites were much higher, and did not fit the model.

Fast Evaluation of Differential Capacity and Surface Charge in Electrical Double Layers with A.C. Oscillopolarography

2000 ◽  
Vol 65 (3) ◽  
pp. 371-379 ◽  
Author(s):  
Shuping Bi ◽  
Hong Gao ◽  
Wei Tang ◽  
Zhiguo Yang ◽  
Sidan Du ◽  
...  
Keyword(s):  
Surface Charge ◽  
Analytical Procedure ◽  
Low Cost ◽  
Mercury Electrode ◽  
Double Layers ◽  
Differential Capacity ◽  
Fast Evaluation ◽  
Charge Densities ◽  
Electrical Double Layers ◽  
Simple Manipulation

The application of a.c. oscillopolarography for a fast evaluation of differential capacity and surface charge in electrical double layers on the mercury electrode is described. The Cd = f(E), Q = f(E) and γ = f(E) functions are displayed. The obtained values of differential capacity and surface charge densities are in agreement with those from the a.c. bridge method. The new method has the distinct advantages of a rapid analytical procedure, visual detection, very simple manipulation and low-cost instrumentation. It is very useful in practical analysis where accurate values of differential capacity and surface charge are not required.

Interface Analysis of a Combined Electroosmotic/Pressure Driven Flow of Three Viscoelastic Immiscible Fluids in a Microchannel

2017 ◽  
Author(s):  
Juan P. Escandón ◽  
Juan R. Gómez ◽  
Clara G. Hernández
Keyword(s):  
Surface Charge ◽  
Slip Surface ◽  
Flow Behavior ◽  
External Pressure ◽  
Immiscible Fluids ◽  
Charge Densities ◽  
Poisson Boltzmann Equation ◽  
Pressure Driven Flow ◽  
Viscous Stresses ◽  
Pressure Driven

This paper presents the analytical solution of a combined electroosmotic/pressure driven flow of three viscoelastic immiscible fluids in a parallel flat plate microchannel. The mathematical model is based in the Poisson-Boltzmann equation and Cauchy momentum conservation equation. In the steady state analysis, we consider that the three fluids are electric conductors and obey to the simplified Phan-Thien-Tanner rheological model; therefore, different conditions at the interface between the fluids as electric slip, surface charge density and electro-viscous stresses balance are discussed in detail. Results show the transport phenomena coupled in the description of the velocity profiles, by the analyzing of the dimensionless parameters obtained, such as: the electric slips, the electric permittivities ratios, the surface charge densities, the zeta potentials at the walls, the interfaces positions, the viscosity ratios, the viscoelastic and electrokinetic parameters, and the term involving the external pressure gradient. Here, the presence of a net electric charges balance at the interface, breaks the continuity of shear viscous stresses, modifying the flow field; hence, for the established electric conditions at the interface through the values of the electric slips and the surface charge densities, play a role like a switch on the flow behavior. This investigation extends the knowledge about the techniques on the control of immiscible non-Newtonian fluids in microescale.

Analysis of Combined Electroosmotic and Pressure Driven Flow of Multilayer Immiscible Fluids in a Narrow Capillary

2019 ◽  
Author(s):  
Juan P. Escandón ◽  
David A. Torres
Keyword(s):  
Surface Charge ◽  
Stokes Equations ◽  
Flow Behavior ◽  
Immiscible Fluids ◽  
Shear Stresses ◽  
Charge Densities ◽  
Narrow Capillary ◽  
Viscous Shear ◽  
Pressure Driven Flow ◽  
Pressure Driven

Abstract This paper presents the analytical solution of a combined electroosmotic and pressure driven flow of multilayer immiscible fluids in a narrow capillary. The mathematical model is based in the Poisson-Boltzmann equation and the modified Navier-Stokes equations. In the steady-state analysis, we consider different conditions at the interfaces between the fluids as potential differences, surface charge densities and electro-viscous stresses balances, which are discussed in detail. Results show the transport phenomena coupled in the description of velocity distribution, by the analyzing of the dimensionless parameters obtained, such as: potential differences, surface charge densities, electrokinetic parameters, term involving the external pressure gradient, ratios of viscosity and of dielectric permittivity. Here, the presence of a net electric charges balance at the interfaces breaks the continuity of the electric potential distributions and viscous shear stresses, modifying the flow field; thus, the electrical conditions established at the interfaces play an important role on the flow behavior. The present work, in which the velocity field is described, aims to be an important contribution in the development of theoretical models that provide a better understanding about labs-on-a-chip design.

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