NOTE ON THE THEORY OF ELECTROLYTIC DOUBLE LAYERS

1949 ◽  
Vol 27b (7) ◽  
pp. 682-687
Author(s):  
A. J. Dekker
Keyword(s):  
Double Layer ◽  
Double Layers ◽  
Diffuse Double Layer ◽  
Diffuse Part ◽  
Convenient Formula

The mechanism suggested by Gurney for the formation of a double layer at the interface of a metal and a solution containing its ions is applied to a diffuse double layer. The diffuse part of the double layer is treated in a way that differs from Stern's method, leading to a more convenient formula for the potential ψδ of the diffuse part. Numerical values and a comparison with Stern's results are given.

scholarly journals On the diffuse double layer

1933 ◽  
Vol 139 (839) ◽  
pp. 596-603 ◽  
Keyword(s):  
Double Layer ◽  
Colloidal Particles ◽  
Mutual Influence ◽  
Streaming Potential ◽  
Specific Adsorption ◽  
Double Layers ◽  
Diffuse Double Layer ◽  
Plane Parallel ◽  
Parallel Surfaces

1. The formulæ derived by Gouy for the diffuse double layer hold only in the case of a single surface in an infinite amount of medium. In practice they are not very suitable, for very frequently we have to deal either with capillaries, as in streaming potential measurements, or with colloidal particles which may be near enough to influence one another. In these cases it is too difficult to calculate the effect of the mutual influence of two double layers, though in less complicated systems it is possible. Suppose we have two plane parallel surfaces separated by a distance 2 h and charged both to the same potential, in a solution of an electrolyte. If the dimensions of the surfaces are large compared with the distance h there will be no drop of potential between the two. We therefore need to make the assumption (which was superfluous in Gouy’s case) of a specific adsorption by the surface of one or more of the ions in the solution, otherwise there will be no double layer at all; the same effect will also be obtained if ions of the surface dissolve.

Salt diffusion in charged porous media

2020 ◽  
Author(s):  
Pavan Cornelissen ◽  
Anton Leijnse ◽  
Vahid Joekar-Niasar ◽  
Sjoerd van der Zee
Keyword(s):  
Porous Media ◽  
Diffusion Coefficient ◽  
Double Layer ◽  
Effective Diffusion ◽  
Pore Network ◽  
Salt Transport ◽  
Double Layers ◽  
Diffuse Double Layer ◽  
Low Salinity ◽  
Charged Surfaces

<p>Some porous media such as clay have charged surfaces. The presence of these charged surfaces results in a complex system where water flow, salt transport, and the electric field are coupled. This system is important in many fields, such as geotechnical engineering, storage of radioactive waste in clay barriers, enhanced oil recovery, and irrigation with marginal water. The charged surfaces alter the transport properties of ions. For example, clay minerals are often negatively charged due to isomorphous substitution. Cations are therefore attracted to the mineral surface, while anions are repelled, creating a diffuse double layer around the clay particle. Cations are therefore transported preferably over anions through such charged pores. To conserve electroneutrality, a streaming potential develops to counteract diffusion by electromigration. This results in smaller effective diffusion coefficients compared to uncharged porous media. We developed a pore-network model to quantify the effect of the double layer processes on the effective diffusion coefficient. Pore-network models are a suitable tool to include the heterogeneity of pore sizes and surface charge densities seen in nature. In pore-network modeling, the geometry of the pore space is simplified, but the network properties are based on realistic statistics such as pore size distribution and connectivity. The larger scale behavior can be identified by averaging over a large number of pores. The results were strongly dependent on the salinity, as this controls the thickness of the double layers. At high salt concentrations, the diffuse double layer is thin and the differences between charged and uncharged porous media are negligible. However, at low salinity, the double layers are thick and the effective diffusion coefficient of salt was reduced by 25% in charged porous media compared to uncharged porous media, due to salt transport being slowed down to conserve electroneutrality. Hence, the presence of charged mineral surfaces can significantly alter transport rates under low salinity conditions.</p>

Bulk stresses due to deformation of the electrical double layer around a charged sphere

1978 ◽  
Vol 85 (4) ◽  
pp. 673-683 ◽  
Author(s):  
William B. Russel
Keyword(s):  
Shear Flow ◽  
Double Layer ◽  
Electrical Double Layer ◽  
Extensional Flow ◽  
Structural Deformation ◽  
Double Layers ◽  
Surface Charges ◽  
Small Surface ◽  
Bulk Stress ◽  
Diffuse Part

A charged particle suspended in an electrolyte solution attracts ions of opposite charge and repels those of like charge. The surface charge and the resulting distributed charge in the fluid comprise an electrical double layer. When a shear flow deforms the diffuse part of the double layer from equilibrium, stresses are generated which make the effective viscosity of the suspension greater than it would be if there were no charges present. In this paper these stresses are calculated for a dilute dispersion of spheres which have small surface charges and which are surrounded by thin double layers. The viscosity is predicted to be Newtonian in extensional flow but shear-thinning with non-zero normal-stress differences in shear flow. For more complex flows a constitutive equation couples the bulk stress directly to the micro-structural deformation responsible for non-Newtonian effects.

Cracking at the fold in double layer coated paper: the influence of latex and starch composition

TAPPI Journal ◽  
2019 ◽  
Vol 18 (2) ◽  
pp. 93-99
Author(s):  
SEYYED MOHAMMAD HASHEMI NAJAFI ◽  
DOUGLAS BOUSFIELD, ◽  
MEHDI TAJVIDI
Keyword(s):  
Mechanical Properties ◽  
Double Layer ◽  
Starch Content ◽  
Single Layer ◽  
Double Layers ◽  
Coated Paper ◽  
Coated Papers ◽  
Coating Layers ◽  
Scanned Images ◽  
Packaging Paper

Cracking at the fold of publication and packaging paper grades is a serious problem that can lead to rejection of product. Recent work has revealed some basic mechanisms and the influence of various parameters on the extent of crack area, but no studies are reported using coating layers with known mechanical properties, especially for double-coated systems. In this study, coating layers with different and known mechanical properties were used to characterize crack formation during folding. The coating formulations were applied on two different basis weight papers, and the coated papers were folded. The binder systems in these formulations were different combinations of a styrene-butadiene latex and mixtures of latex and starch for two different pigment volume concentrations (PVC). Both types of papers were coated with single and double layers. The folded area was scanned with a high-resolution scanner while the samples were kept at their folded angle. The scanned images were analyzed within a constant area. The crack areas were reported for different types of papers, binder system and PVC values. As PVC, starch content, and paper basis weight increased, the crack area increased. Double layer coated papers with high PVC and high starch content at the top layer had more cracks in comparison with a single layer coated paper, but when the PVC of the top layer was low, cracking area decreased. No measurable cracking was observed when the top layer was formulated with a 100% latex layer.

CRITICAL CURRENTS AND NEW EXPERIMENTS ON EXCITONIC ELECTRON BILAYER SYSTEMS

2009 ◽  
Vol 23 (12n13) ◽  
pp. 2596-2602
Author(s):  
LARS TIEMANN ◽  
WERNER DIETSCHE ◽  
MAIK HAUSER ◽  
KLAUS v. KLITZING
Keyword(s):  
Double Layer ◽  
Filling Factor ◽  
Direct Consequence ◽  
Bose Condensation ◽  
Critical Currents ◽  
Phase Coherence ◽  
Double Layers

Pure dc interlayer tunneling experiments have found critical currents Icritical in electron double layers at a total filling factor of one. Below Icritical, the four-terminal interlayer resistance is very small but abruptly increases by many orders of magnitude once I > Icritical. The nearly vanishing 4-terminal interlayer resistance is most likely the direct consequence of the interlayer phase-coherence associated with the Bose condensation of the double layer quasi-excitons at total filling factor one.

Ion-acoustic solitary structures at the acoustic speed in a collisionless magnetized nonthermal dusty plasma

2021 ◽  
Vol 0 (0) ◽  
Author(s):  
Debdatta Debnath ◽  
Anup Bandyopadhyay
Keyword(s):  
Double Layer ◽  
Negative Polarity ◽  
Critical Value ◽  
Magnetized Plasma ◽  
Double Layers ◽  
Nonthermal Electrons ◽  
Solitary Structures ◽  
Ion Acoustic ◽  
Density Of Electrons ◽  
Acoustic Speed

Abstract At the acoustic speed, we have investigated the existence of ion-acoustic solitary structures including double layers and supersolitons in a collisionless magnetized plasma consisting of negatively charged static dust grains, adiabatic warm ions, and nonthermal electrons. At the acoustic speed, for negative polarity, the system supports solitons, double layers, supersoliton structures after the formation of double layer, supersoliton structures without the formation of double layer, solitons after the formation of double layer whereas the system supports solitons and supersolitons without the formation of double layer for the case of positive polarity. But it is not possible to get the coexistence of solitary structures (including double layers and supersolitons) of opposite polarities. For negative polarity, we have observed an important transformation viz., soliton before the formation of double layer → double layer → supersoliton → soliton after the formation of double layer whereas for both positive and negative polarities, we have observed the transformation from solitons to supersolitons without the formation of double layer. There does not exist any negative (positive) potential solitary structures within 0 < μ < μ c (μ c < μ < 1) and the amplitude of the positive (negative) potential solitary structure decreases for increasing (decreasing) μ and the solitary structures of both polarities collapse at μ = μ c, where μ c is a critical value of μ, the ratio of the unperturbed number density of electrons to that of ions. Similarly there exists a critical value β e2 of the nonthermal parameter β e such that the solitons of both polarities collapse at β e = β e2.

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.

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