SURFACE ELECTRICAL CONDUCTANCE AND ELECTROKINETIC POTENTIALS IN NETWORKS OF FIBROUS MATERIALS

1959 ◽  
Vol 37 (7) ◽  
pp. 1153-1164 ◽  
Author(s):  
C. E. Mossman ◽  
S. G. Mason
Keyword(s):  
Specific Surface ◽  
Double Layer ◽  
Electrical Double Layer ◽  
Electrolyte Concentration ◽  
Electrical Conductance ◽  
Surface Conductivity ◽  
Capillary Network ◽  
Fibrous Materials ◽  
Ζ Potential ◽  
Conductance Data

Stream-current, permeability, and conductance measurements were made on cylindrical pads of randomly oriented Dacron, glass, Nylon, and Orlon fibers over a range of electrolyte and solid concentrations. Values of the specific surface conductivity were computed from the conductance data, using equations which were derived from a capillary network theory.The measured conductance values were independent of pad concentration, increased with increasing electrolyte concentration, and were higher than values calculated from electrical double-layer theory using the measured values of ζ-potential. A number of plausible reasons for the discrepancies are advanced.

scholarly journals Synthesis of a Very High Specific Surface Area Active Carbon and Its Electrical Double-Layer Capacitor Properties in Organic Electrolytes

2020 ◽  
Vol 4 (3) ◽  
pp. 43 ◽  
Author(s):  
Zheng Yue ◽  
Hamza Dunya ◽  
Maziar Ashuri ◽  
Kamil Kucuk ◽  
Shankar Aryal ◽  
...  
Keyword(s):  
Specific Surface ◽  
Surface Area ◽  
Double Layer ◽  
Specific Surface Area ◽  
Electrical Double Layer ◽  
High Specific Surface Area ◽  
Koh Activation ◽  
Electrical Double Layer Capacitor ◽  
Double Layer Capacitor ◽  
Very High

A new porous activated carbon (AC) material with very high specific surface area (3193 m2 g−1) was prepared by the carbonization of a colloidal silica-templated melamine–formaldehyde (MF) polymer composite followed by KOH-activation. Several electrical double-layer capacitor (EDLC) cells were fabricated using this AC as the electrode material. A number of organic solvent-based electrolyte formulations were examined to optimize the EDLC performance. Both high specific discharge capacitance of 130.5 F g−1 and energy density 47.9 Wh kg−1 were achieved for the initial cycling. The long-term cycling performance was also measured.

A laboratory investigation of the thermoelectric effect

Geophysics ◽  
2016 ◽  
Vol 81 (4) ◽  
pp. E243-E257 ◽  
Author(s):  
A. Revil ◽  
C. D. Meyer ◽  
Q. Niu
Keyword(s):  
Seebeck Coefficient ◽  
Double Layer ◽  
Electrical Double Layer ◽  
High Surface ◽  
Surface Conductivity ◽  
Berea Sandstone ◽  
Mobile Ions ◽  
Intermediate Surface ◽  
Self Potential ◽  
Layer Coating

One contribution to self-potential signals is the thermoelectric coupling associated with a temperature gradient in a porous material, which causes mobile ions to diffuse from hot to cold regions. We have developed 35 laboratory experiments to measure the value of the Seebeck coefficient in two clean (silica) sands and two clayey sandstones fully saturated by NaCl solutions to explore the influence of salinity upon the Seebeck coefficient over four orders of magnitude in salinity. The two sands are characterized by two distinct grain sizes (coarse and medium) and therefore two low values of surface conductivity. Portland sandstone, rich in illite and kaolinite, is characterized by a high surface conductivity, and the Berea sandstone is characterized by an intermediate surface conductivity. The Seebeck coefficient of the sands ranges from [Formula: see text] (at intermediate salinities) to [Formula: see text] at very low salinities, for which surface conductivity, associated with electromigration and electrodiffusion in the electrical double layer, dominates. For the Portland sandstone, the Seebeck coefficient is positive in the range [Formula: see text] to [Formula: see text] and decreases with the increase of the salinity. A similar trend is observed for the Berea sandstone with the Seebeck coefficient going from positive to negative values at high salinity. Our experimental data can be fairly reproduced by a simple model accounting for the effect of surface conductivity due to the electrical double layer coating the surface of the grains and the dependence on salinity of the partial entropies of the ions in the pore water.

Modeling the Electrical Double Layer to Understand the Reaction Environment in a CO2 Electrocatalytic System

2019 ◽  
Author(s):  
Divya Bohra ◽  
Jehanzeb Chaudhry ◽  
Thomas Burdyny ◽  
Evgeny Pidko ◽  
wilson smith
Keyword(s):  
Electric Field ◽  
Double Layer ◽  
Electrical Double Layer ◽  
Surface Reaction ◽  
Catalyst Surface ◽  
Local Reaction ◽  
Reaction Diffusion ◽  
Alkali Metal Cations ◽  
Applied Potential ◽  
Critical Aspect

<p>The environment of a CO<sub>2</sub> electroreduction (CO<sub>2</sub>ER) catalyst is intimately coupled with the surface reaction energetics and is therefore a critical aspect of the overall system performance. The immediate reaction environment of the electrocatalyst constitutes the electrical double layer (EDL) which extends a few nanometers into the electrolyte and screens the surface charge density. In this study, we resolve the species concentrations and potential profiles in the EDL of a CO<sub>2</sub>ER system by self-consistently solving the migration, diffusion and reaction phenomena using the generalized modified Poisson-Nernst-Planck (GMPNP) equations which include the effect of volume exclusion due to the solvated size of solution species. We demonstrate that the concentration of solvated cations builds at the outer Helmholtz plane (OHP) with increasing applied potential until the steric limit is reached. The formation of the EDL is expected to have important consequences for the transport of the CO<sub>2</sub> molecule to the catalyst surface. The electric field in the EDL diminishes the pH in the first 5 nm from the OHP, with an accumulation of protons and a concomitant depletion of hydroxide ions. This is a considerable departure from the results obtained using reaction-diffusion models where migration is ignored. Finally, we use the GMPNP model to compare the nature of the EDL for different alkali metal cations to show the effect of solvated size and polarization of water on the resultant electric field. Our results establish the significance of the EDL and electrostatic forces in defining the local reaction environment of CO<sub>2</sub> electrocatalysts.</p>

Electrical Double Layer Formation on Glassy Carbon in Aqueous Solution

2021 ◽  
pp. 138416
Author(s):  
Sofia B. Davey ◽  
Amanda P. Cameron ◽  
Kenneth G. Latham ◽  
Scott W. Donne
Keyword(s):  
Aqueous Solution ◽  
Double Layer ◽  
Glassy Carbon ◽  
Electrical Double Layer ◽  
Layer Formation

Enzyme Immobilization Behavior on the Surface of Hydroxyapatite Capsules under Alkaline Condition

2018 ◽  
Vol 782 ◽  
pp. 21-26
Author(s):  
Takeshi Yabutsuka ◽  
Masaya Yamamoto ◽  
Shigeomi Takai ◽  
Takeshi Yao
Keyword(s):  
Enzyme Immobilization ◽  
Double Layer ◽  
Isoelectric Point ◽  
Electrical Double Layer ◽  
Alkaline Condition ◽  
Bicarbonate Buffer

We prepared hydroxyapatite (HA) capsules encapsulating maghemite particles. In order to evaluate enzyme immobilization behavior of the HA capsules under alkaline condition, we immobilized five kinds of enzymes with different isoelectric point in carbonate/bicarbonate buffer (CBB, pH 10.0). When the enzymes in CBB were moderately charged, immobilization efficiency on the HA capsules showed the highest value. It was suggested that immobilization efficiency was affected according to both pI of enzyme and pH of the surrounding solution and that enzyme immobilized on the HA capsules by not only electrical double layer interactions but also ion interaction and other interactions.

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