Double layer forces between heterogeneous charged surfaces: The effect of net surface charge

1995 ◽  
Vol 103 (11) ◽  
pp. 4794-4806 ◽  
Author(s):  
S. J. Miklavcic
Keyword(s):  
Surface Charge ◽  
Double Layer ◽  
Charged Surfaces

scholarly journals Untangling superposed double layer and structural forces across confined nanoparticle suspensions

2021 ◽  
Author(s):  
Michael Ludwig ◽  
Regine von Klitzing
Keyword(s):  
Double Layer ◽  
Interaction Force ◽  
Charged Surfaces ◽  
Structural Forces ◽  
Nanoparticle Suspensions ◽  
Confined Suspensions ◽  
Force Profiles

Complete interaction force profiles of charged surfaces across confined suspensions were successfully described using a superposition of double layer and structural forces.

scholarly journals Bulk and Surface Aqueous Speciation of Calcite: Implications for Low-Salinity Waterflooding of Carbonate Reservoirs

SPE Journal ◽  
2017 ◽  
Vol 23 (01) ◽  
pp. 84-101 ◽  
Author(s):  
Maxim P. Yutkin ◽  
Himanshu Mishra ◽  
Tadeusz W. Patzek ◽  
John Lee ◽  
Clayton J. Radke
Keyword(s):  
Ionic Strength ◽  
Ion Exchange ◽  
Crude Oil ◽  
Surface Charge ◽  
Double Layer ◽  
Carbonate Reservoir ◽  
Carbonate Reservoirs ◽  
Diffuse Double Layer ◽  
Low Salinity ◽  
Low Salinity Waterflooding

Summary Low-salinity waterflooding (LSW) is ineffective when reservoir rock is strongly water-wet or when crude oil is not asphaltenic. Success of LSW relies heavily on the ability of injected brine to alter surface chemistry of reservoir crude-oil brine/rock (COBR) interfaces. Implementation of LSW in carbonate reservoirs is especially challenging because of high reservoir-brine salinity and, more importantly, because of high reactivity of the rock minerals. Both features complicate understanding of the COBR surface chemistries pertinent to successful LSW. Here, we tackle the complex physicochemical processes in chemically active carbonates flooded with diluted brine that is saturated with atmospheric carbon dioxide (CO2) and possibly supplemented with additional ionic species, such as sulfates or phosphates. When waterflooding carbonate reservoirs, rock equilibrates with the injected brine over short distances. Injected-brine ion speciation is shifted substantially in the presence of reactive carbonate rock. Our new calculations demonstrate that rock-equilibrated aqueous pH is slightly alkaline quite independent of injected-brine pH. We establish, for the first time, that CO2 content of a carbonate reservoir, originating from CO2-rich crude oil and gas, plays a dominant role in setting aqueous pH and rock-surface speciation. A simple ion-complexing model predicts the calcite-surface charge as a function of composition of reservoir brine. The surface charge of calcite may be positive or negative, depending on speciation of reservoir brine in contact with the calcite. There is no single point of zero charge; all dissolved aqueous species are charge determining. Rock-equilibrated aqueous composition controls the calcite-surface ion-exchange behavior, not the injected-brine composition. At high ionic strength, the electrical double layer collapses and is no longer diffuse. All surface charges are located directly in the inner and outer Helmholtz planes. Our evaluation of calcite bulk and surface equilibria draws several important inferences about the proposed LSW oil-recovery mechanisms. Diffuse double-layer expansion (DLE) is impossible for brine ionic strength greater than 0.1 molar. Because of rapid rock/brine equilibration, the dissolution mechanism for releasing adhered oil is eliminated. Also, fines mobilization and concomitant oil release cannot occur because there are few loose fines and clays in a majority of carbonates. LSW cannot be a low-interfacial-tension alkaline flood because carbonate dissolution exhausts all injected base near the wellbore and lowers pH to that set by the rock and by formation CO2. In spite of diffuse double-layer collapse in carbonate reservoirs, surface ion-exchange oil release remains feasible, but unproved.

Li-insertion Behavior in NanocrystallineTiO2-(MoO3)z Core-Shell Materials

2000 ◽  
Vol 658 ◽  
Author(s):  
Gregory J. Moore ◽  
Dominique Guyomard ◽  
Scott H. Elder
Keyword(s):  
Transition Metal ◽  
Surface Charge ◽  
Double Layer ◽  
Single Phase ◽  
Inductive Effect ◽  
Core Shell ◽  
Fundamental Study ◽  
The Core ◽  
Single Phase Material

ABSTRACTA fundamental study of the Li insertion behavior of a series of materials consisting of a TiO2 core having MoO3 on the surface has been carried out in order to determine the influence of the shell. These TiO2-(MoO3)z materials, where (z) denotes the fraction of coverage from a partial to a double layer, range in diameter from 40-100 Å. Calculations have been done on their theoretical lithium capacity using a maximum of Li0.5TiO2 for the core, and Li1.5MoO3 at the TiO2/MoO3 interface, and they have been compared to that found experimentally. The reversible Li-insertion capacity was shown to increase from 0.34 per Ti for the pure TiO2 sample, to 0.91 Li per transition metal when the MoO3 coverage increased to one monolayer. There was only one plateau observed in the electrochemical scans for the samples showing that they function as a single-phase material making them interesting for electrodes. The redox voltage of the TiO2/Li0.5TiO2 biphasic transformation increased 60 mV from the pure TiO2 to the sample containing one monolayer of MoO3. This effect was interpreted as due to a change in TiO2 surface charge coming from an inductive effect of Ti-O-Mo bonds.

scholarly journals Influence of the Ionic Composition of Fluid Medium on Red Cell Aggregation

1973 ◽  
Vol 61 (5) ◽  
pp. 655-668 ◽  
Author(s):  
Kung-Ming Jan ◽  
Shu Chien
Keyword(s):  
Ionic Strength ◽  
Surface Charge ◽  
Double Layer ◽  
Surface Potential ◽  
Electric Double Layer ◽  
Divalent Cations ◽  
Ionic Composition ◽  
Cell Aggregation ◽  
Fluid Medium ◽  
Induced Aggregation

The effects of ionic strength and cationic valency of the fluid medium on the surface potential and dextran-induced aggregation of red blood cells (RBC's) were investigated. The zeta potential was calculated from cell mobility in a microelectrophoresis apparatus; the degree of aggregation of normal and neuraminidase-treated RBC's in dextrans (Dx 40 and Dx 80) was quantified by microscopic observation, measurement of erythrocyte sedimentation rate, and determination of low-shear viscosity. A decrease in ionic strength caused a reduction in aggregation of normal RBC's in dextrans, but had no effect on the aggregation of neuraminidase-treated RBC's. These findings reflect an increase in electrostatic repulsive force between normal RBC's by the reduction in ionic strength due to (a) a decrease in the screening of surface charge by counter-ions and (b) an increase in the thickness of the electric double layer. Divalent cations (Ca++, Mg++, and Ba++) increased aggregation of normal RBC's in dextrans, but had no effect on the aggregation of neuraminidase-treated RBC's. These effects of the divalent cations are attributable to a decrease in surface potential of normal RBC's and a shrinkage of the electric double layer. It is concluded that the surface charge of RBC's plays a significant role in cell-to-cell interactions.

Effective surface charge for symmetric electrolytes in the primitive model double layer

1996 ◽  
Vol 41 (14) ◽  
pp. 2115-2124 ◽  
Author(s):  
Jonathan Ennis ◽  
Stjepan Marčelja ◽  
Roland Kjellander
Keyword(s):  
Surface Charge ◽  
Double Layer ◽  
Effective Surface ◽  
Primitive Model
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