The effects of counter ion nature on the adsorption of nitrate ion at the mercury/solution interface

1977 ◽  
Vol 55 (22) ◽  
pp. 3871-3881 ◽  
Author(s):  
W. Ronald Fawcett ◽  
James B. Sellan
Keyword(s):  
Ionic Strength ◽  
Ion Concentration ◽  
Surface Excess ◽  
Charge Effects ◽  
Nitrate Ion ◽  
Anion Adsorption ◽  
Solution Interface ◽  
Ionic Adsorption ◽  
Counter Ion ◽  
Capacity Data

The adsorption of nitrate ion at mercury has been studied from two systems at constant ionic strength, namely, xM NaNO3 + (0.2 − x) M NaF and x M KNO3 + (0.2 − x) M KF. The surface excess due to adsorbed nitrate ions was determined from differential capacity data using a modified version of the Hurwitz–Parsons analysis which takes into consideration variation in ionic activity coefficients with solution composition. The amount of adsorbed nitrate ion at a given electrode charge density and bulk nitrate ion concentration is shown to depend markedly on both ionic strength and the nature of the counter ion at the outer Helmholtz plane; when the charge in the diffuse layer is positive, an increase in ionic strength results in more anion adsorption and vice versa. A change in the cation from Na+ to K+ also results in increased anion adsorption. The effects observed are discussed in terms of the Stern–Grahame–Levine model for ionic adsorption which is based on an electrostatic description of the charged interface with consideration of discreteness-of-charge effects.

Discreteness-of-charge effects in electrode kinetics. I. The electroreduction of tetrathionate anion in the presence of specifically adsorbed iodide anions

1982 ◽  
Vol 60 (15) ◽  
pp. 2038-2045 ◽  
Author(s):  
W. Ronald Fawcett ◽  
Kveta Markušová
Keyword(s):  
Ionic Strength ◽  
Electrode Potential ◽  
Ion Concentration ◽  
Electrode Kinetics ◽  
Charge Effect ◽  
Charge Effects ◽  
Potential Analysis ◽  
Rate Of Reaction ◽  
Kinetics Of ◽  
Outer Helmholtz Plane

The kinetics of electroreduction of tetrathionate anion have been studied at a Hg electrode in aqueous solutions of Nal + NaF and KI + KF with an ionic strength of 0.25 M. The rate of reaction was observed to decrease as the iodide ion concentration was increased, and when the cation was changed from K+ to Na+ at constant electrode potential. Analysis of the double layer effects on the basis of the Frumkin model results in an overestimation of the repulsive effect of the adsorbed iodide anions. This result is interpreted on the basis of the discreteness-of-charge effect and the possible non-coincidence of the reaction plane and outer Helmholtz plane.

Residual phase lignin in haft cooking related to the conditions in the cook

1997 ◽  
Vol 12 (4) ◽  
pp. 225-229
Author(s):  
Cart-in A-S. Gustavsson ◽  
Chritofer T. Lindgren ◽  
Mikael E. Lindström
Keyword(s):  
Hydrogen Sulfide ◽  
Ionic Strength ◽  
Sodium Ion ◽  
Ion Concentration ◽  
Constant Composition ◽  
Hydroxide Ion ◽  
Sulfide Ion ◽  
Residual Phase ◽  
Kraft Cooking ◽  
Very High

Abstract The amount of lignin reacting according to the slow residual phase, i.e. the residual phase lignin, is in many perspectives an interesting issue. The purpose of the present investigation was to develop a mathematical model to show how the amount of residual phase lignin in the kraft cooking of spruce chips (Picm ahies) depends on the conditions in the earlier phases of the cook. The variables studied were hydroxide ion concentration, hydrogen sulfide ion concentration and ionic strength. The liquor-to-wood ratio during pulping was very high to maintain approximately constant chemical concentrations throughout each experiment (so called "constant composition" cooks). An increase in hydroxide ion concentration andtor hydrogen sulfide ion concentration leads to a decrease in the amount of residual phase lignin, while an increase in ionic strength, i.e. sodium ion concentration, leads to an increase. A signiticant result is that the hydrogen sulfide ion concentration has a pronounced influence on the amount of residual phase lignin during a cook at a low hydroxide ion concentration. The amount of residual phase lignin expressed as % lignin on wood, L,, can be described by the following equation developed for "constant composition" cooks (when cooking with a constant sodium ion concentration of 2 mol/L): LT=0,55-0.32*[HO-](-1,3)*ln[HS-] This equation is valid for a concentration of HO- in the range from 0.17 to 1.4, and a hydrogen sulfide ion concentration from 0.07 to 0.6 mol/L.

Surfactant-modified graphite surfaces in biological analysis: ionic strength and ion charge effects

1993 ◽  
Vol 65 (23) ◽  
pp. 3441-3446 ◽  
Author(s):  
Alonso. Jaramillo ◽  
Ana. Marino ◽  
Anna. Brajter-Toth
Keyword(s):  
Ionic Strength ◽  
Charge Effects ◽  
Biological Analysis

Behavior of Polyelectrolyte Gels in Concentrated Solutions of Highly Soluble Salts

MRS Advances ◽  
2020 ◽  
Vol 5 (17) ◽  
pp. 907-915 ◽  
Author(s):  
Jessica L. Sargent ◽  
Xunkai Chen ◽  
Mitchell C. Brezina ◽  
Sebastian Aldwin ◽  
John A. Howarter ◽  
...  
Keyword(s):  
Transition Metal ◽  
Metal Ions ◽  
High Performance Concrete ◽  
Group Versus ◽  
Transition Metal Ions ◽  
Main Group ◽  
Ion Concentration ◽  
Polyelectrolyte Gels ◽  
Counter Ion ◽  
Versus Transition

ABSTRACTIonic hydrogels are an abundant class of materials with applications ranging from drug delivery devices to high performance concrete to baby diapers. A more thorough understanding of interactions between polyelectrolyte networks and ionic solutes is critical as these materials are further tailored for performance applications in highly targeted ionic environments. In this work, we seek to develop structure-property relationships between polyelectrolyte gels and environments containing high concentrations of multivalent ions. Specifically, this work seeks to elucidate the causes behind differences in hydrogel response to divalent ions of main group metals versus transition metals. PANa-co-PAM hydrogels containing low and high fractions of ionic groups are investigated in solutions of DI water, NaCl, CaCl2, and CuSO4 at concentrations ranging from 5 to 100 mM in order to understand 1) the transient or permanent nature of crosslinks produced in these networks by divalent counter-ions, 2) the role of polymer ionic content in these interactions, and 3) how these interactions scale with salt concentration. Gravimetric swelling and mechanical compression testing are employed to characterize water and salt-swollen hydrogels in order to develop guiding principles to control and manipulate material properties through polymer-counter-ion interactions. The work presented here confirms the formation of permanent crosslinks by transition metal ions, offers explanation for the behavioral discrepancy observed between ionic hydrogels and main group versus transition metal ions, and illustrates how such hydrogel properties scale with counter-ion concentration.

Discreteness-of-charge effects in electrode kinetics. III. The electroreduction of aquopentamminochromium(III) cation in the presence of specifically adsorbed iodide anions

1984 ◽  
Vol 62 (8) ◽  
pp. 1497-1501 ◽  
Author(s):  
W. Ronald Fawcett ◽  
Kveta Markušová
Keyword(s):  
Ionic Strength ◽  
Electrode Kinetics ◽  
Reaction Site ◽  
Charge Effects ◽  
Iodide Concentration ◽  
Rate Acceleration ◽  
Rate Of Reaction ◽  
Layer Effect ◽  
Kinetics Of ◽  
Outer Helmholtz Plane

The kinetics of electroreduction of the aquopentamminochromium(III) cation have been studied at a Hg electrode in acidified aqueous solutions of NaI+ NaClO4 with an ionic strength of 0.25 M. The rate of reaction increased with increase in iodide concentration due to the accelerating effect of this anion when it is adsorbed on the electrode. Analysis of the double layer effect indicates that the rate acceleration is greater than that predicted by the Frumkin theory chiefly because the reaction site is closer to the electrode than to the outer Helmholtz plane.

Interaction between effects of low pH and low ion concentration on mortality during early development of medaka, Oryzias latipes

1989 ◽  
Vol 67 (9) ◽  
pp. 2158-2168 ◽  
Author(s):  
Weerawan Chulakasem ◽  
Jay A. Nelson ◽  
John J. Magnuson
Keyword(s):  
Ionic Strength ◽  
Oryzias Latipes ◽  
Calcium Content ◽  
Explanatory Models ◽  
Low Ph ◽  
Ion Concentration ◽  
Physiological Mechanisms ◽  
Effects Of Ph ◽  
Independent Effects ◽  
Patterns Of Interaction

Eggs and fry of medaka, Oryzias latipes, were incubated continuously from shortly after fertilization until 7 days after hatching using a factorial design with four water conductivities (9, 16, 28, and 49 μS/cm) and four pH levels (4.2, 4.5, 5.6, or 6.6). Results on survival suggest that only during hatching can independent effects of pH and ionic strength be statistically separated. Mortalities of encapsulated embryos and fry were determined by interactions between pH and ionic strength. Sensitivity to dilute, low pH water was greatest in freshly fertilized eggs and 1- to 4-day-old fry. Egg mortality occurred within a day after water hardening, whereas fry mortality occurred more gradually over the 3 days following hatching. Dilute, low pH water did not influence oxygen consumption or calcium content of eggs, yet impeded normal developmental increases in both calcium content and metabolic rate in fry. Results are discussed mechanistically with respect to causes of the mortality, and two explanatory models are proposed. Speculation that patterns of interaction in multivariate analyses can be indicative of physiological mechanisms also is entertained.

Mechanistic Information from the Effect of Pressure on the Kinetics of Hydrolysis of Iodopentaaquochromium(III) Ion

1975 ◽  
Vol 53 (24) ◽  
pp. 3697-3701 ◽  
Author(s):  
Milton Cornelius Weekes ◽  
Thomas Wilson Swaddle
Keyword(s):  
Ionic Strength ◽  
Hydrogen Ion ◽  
Ion Concentration ◽  
Hydrogen Ion Concentration ◽  
Kinetics Of Hydrolysis ◽  
Rate Of Hydrolysis ◽  
Kinetics Of ◽  
Hydrolysis Of ◽  
Aqueous Hclo ◽  
Conjugate Base

The rate of hydrolysis of iodopentaaquochromium(III) ion has been measured as a function of pressure (0.1 to 250 MPa) and hydrogen ion concentration (0.1 to 1.0 mol kg−1) at 298.2 K and ionic strength 1.0 mol kg−1 (aqueous HClO4–LiClO4). The volumes of activation for the acid independent and inversely acid dependent hydrolysis pathways are −5.4 ± 0.5 and −1.6 ± 0.3 cm3 mol−1 respectively, and are not detectably pressure-dependent. Consideration of these values, together with the molar volume change of −3.3 ± 0.3 cm3 mol−1 determined dilatometrically for the completed hydrolysis reaction, indicates that the mechanisms of the two pathways are associative interchange (Ia) and dissociative conjugate base (Dcb) respectively.

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