Faradaic Admittance and Migration in the Diffuse Double-Layer: Effect on the Phase Angle

1963 ◽  
Vol 16 (4) ◽  
pp. 565 ◽  
Author(s):  
K Narayanan ◽  
SK Rangarajan
Keyword(s):  
Double Layer ◽  
Phase Angle ◽  
Theoretical Studies ◽  
Diffuse Double Layer ◽  
Faradaic Current ◽  
Layer Effect ◽  
And Migration ◽  
Modified Equation

The effect of migration in the diffuse double-layer on the phase angle between the alternating components of the faradaic current and voltage is discussed. It is shown that the cot � v. √ω relationship is nonlinear and the modified equation for this case (i.e. when migration is taken into account) is given. Equations derived already by Matsuda are discussed. Theoretical studies on the variation of ((Io)app/(Io)ms with Gouy potential are also reported.

scholarly journals Absence of diffuse double layer effect on the vibrational properties and oxidation of chemisorbed carbon monoxide on a Pt(111) electrode

2018 ◽  
Vol 281 ◽  
pp. 127-132 ◽  
Author(s):  
Marta C. Figueiredo ◽  
Dennis Hiltrop ◽  
Ravishankar Sundararaman ◽  
Kathleen A. Schwarz ◽  
Marc T.M. Koper
Keyword(s):  
Carbon Monoxide ◽  
Double Layer ◽  
Vibrational Properties ◽  
Diffuse Double Layer ◽  
Layer Effect

A simple method for the optimization of the decay time in pulse polarography

1988 ◽  
Vol 53 (6) ◽  
pp. 1149-1155
Author(s):  
Jorge A. Bolzan
Keyword(s):  
Double Layer ◽  
Decay Time ◽  
Sampling Time ◽  
Simple Method ◽  
Faradaic Current ◽  
Maximum Value ◽  
Pulse Polarography ◽  
Null Value ◽  
Polarographic Current

A simple method for optimization of the minimum decay time, previous to the sampling time of the polarographic current, is described. The former should make compatible two requisites: it should be short enough for obtaining the maximum value of the faradaic current and long enough for the minimum or null value of the double layer decay current. The method is performed with the pulse polarograph only, without ancillary instruments, is fast and its accuracy is fairly comparable with earlier methods, which were more accurate but by far more involved to perform.

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.

Double-layer effect correction in chronoamperometry with linear potential sweep

1968 ◽  
Vol 13 (2) ◽  
pp. 241-249 ◽  
Author(s):  
M. Caselli ◽  
G.O. Ottombrini ◽  
P. Papoff
Keyword(s):  
Double Layer ◽  
Linear Potential ◽  
Potential Sweep ◽  
Layer Effect

scholarly journals Estimation of Compressibility and Permeability of Very Soft Clays by Means of the Diffuse Double Layer Theory

1991 ◽  
Vol 31 (3) ◽  
pp. 175-184 ◽  
Author(s):  
Hyeongjoo Kim ◽  
Hiroshi Yoshikuni ◽  
Kazuhiro Tsurugasaki
Keyword(s):  
Double Layer ◽  
Diffuse Double Layer ◽  
Soft Clays ◽  
Double Layer Theory
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