Adsorption of Iodide Ion from Aqueous NaI-NaClO4- Butan-1-ol at the Mercury-Electrolyte Interface

1999 ◽  
Vol 64 (12) ◽  
pp. 1925-1936 ◽  
Author(s):  
Jadwiga Saba ◽  
Kazimierz Sykut ◽  
Jolanta Nieszporek ◽  
Jan Szaran
Keyword(s):  
Surface Tension ◽  
Gibbs Energy ◽  
Adsorption Equilibrium ◽  
Standard Gibbs Energy ◽  
Mercury Electrode ◽  
Differential Capacity ◽  
Capacity Zero ◽  
Charge Potential ◽  
Adsorption Layers ◽  
Zero Charge Potential

Properties of the adsorption layers I--ClO4--H2O and I--ClO4--H2O-butan-1-ol on the mercury electrode were described using adsorption and kinetic parameters for the Zn(II) ion reduction. The systems were characterized by the measurements of differential capacity, zero charge potential and surface tension at this potential. The data were analysed to obtain the surface pressure and the charge due to specific adsorption of I- ions as a function of charge and concentration of I- ions. The standard Gibbs energy of adsorption ∆G0ad and parameter B obtained from the virial isotherm were compared. The rate constants of Zn(II) ion reduction as an ion affecting the adsorption equilibrium were determined.

The Mixed Adsorption Layers of Butanol/Thiourea and Butanol/Toluidine at the Interface Hg/Aqueous Perchlorate Solution

1996 ◽  
Vol 61 (7) ◽  
pp. 999-1009 ◽  
Author(s):  
Jadwiga Saba
Keyword(s):  
Standard Gibbs Energy ◽  
Bulk Concentration ◽  
Differential Capacity ◽  
Surface Excess ◽  
Capacity Zero ◽  
Charge Potential ◽  
Two Component ◽  
Adsorption Layers ◽  
Component Adsorption ◽  
Zero Charge Potential

Properties of mixed, two-component adsorption layers of butanol/thiourea, butanol/m-toluidine and butanol/p-toluidine in 1 M NaClO4 were investigated. The systems were characterized by the measurements of differential capacity, zero charge potential and surface tension at this potential. The data were analyzed to obtain the surface pressure and relative surface excess of thiourea, m-toluidine or p-toluidine as a function of charge and bulk concentration of these substances. The standard Gibbs energy of adsorption and parameters α, B obtained from the Frumkin and virial isotherms were compared. The electrostatic parameters of the inner layer were determined.

Adsorption of Butyl Acetate on Mercury Electrode and Its Effect on Electroreduction of Zn Cations

2001 ◽  
Vol 66 (3) ◽  
pp. 411-422 ◽  
Author(s):  
Dorota Gugała ◽  
Dorota Sieńko ◽  
Jadwiga Saba
Keyword(s):  
Butyl Acetate ◽  
Mercury Electrode ◽  
Ester Group ◽  
Interaction Constant ◽  
Base Electrolyte ◽  
Capacity Curves ◽  
Charge Potential ◽  
Strong Adsorption ◽  
Kinetics Of ◽  
Zero Charge Potential

Adsorption of butyl acetate on the mercury electrode in 1 M, 0.5 M or 0.1 M NaClO4 is described. Differential capacity curves obtained in these solutions for various butyl acetate concentrations point to the strongest decrease in capacity in 0.1 M NaClO4 for the smallest concentration of the ester tested. At the same time the heights of desorption peaks in the solutions tested decrease in the following order: 1 M > 0.5 M > 0.1 M NaClO4. The obtained results show dynamic competitive adsorption in the ClO4--H2O-ester system. In all the systems studied the zero charge potential values determined with a streaming electrode are shifted towards positive potential with increasing ester concentration. These results suggest that the polar molecule of the ester adsorbs on the mercury electrode with its hydrophobic end while hydrophilic ester group is directed towards the solution. The values of the relative surface excess obtained in the range of potentials where the strong adsorption occurs, virtually do not depend on the base electrolyte concentration. The values of the Gibbs energy of adsorption ∆G0 determined from the Frumkin isotherm have also similar values at base concentrations of the electrolyte tested. The values of interaction constant A are radically different: the adsorbed molecules undergo repulsive force in 1 M NaClO4, whereas in 0.5 M and 0.1 M NaClO4 they are under weak attraction. In the range of more negative potentials, the adsorption layer was investigated following the kinetics of the reduction of Zn++ as a pilot ion. It was stated that the concentration of the base electrolyte fundamentally affects the process: the inhibition of butyl acetate decreases in the order 1 M > 0.5 M > 0.1 M NaClO4.

scholarly journals Electrode mechanism and voltammetric determination of selected guanidino compounds

2012 ◽  
Vol 10 (4) ◽  
pp. 977-988 ◽  
Author(s):  
Sławomira Skrzypek
Keyword(s):  
Electrochemical Activity ◽  
Differential Capacity ◽  
Guanidino Compounds ◽  
Zero Charge ◽  
Charge Potential ◽  
Protonated Forms ◽  
Adsorption Data ◽  
Adsorption Processes ◽  
Zero Charge Potential

AbstractThe present review describes the recent results on the electrochemical activity of bio-guanidino compounds, such as famotidine, metformin, acyclovir, ganciclovir, zanamivir, moroxydine as well as guanidino compounds, such as S-[(2-guanidino-thiazol-4-yl)methyl]isothiourea hydrochloride, 2-guanidino-1,3-thiazole, 2-guanidinobenzimidazole. The focus is on analyzing the electrode mechanism of the guanidino compounds at the hanging mercury drop electrode and at the silver amalgam film electrode, as well as on the character of the square wave (SW) voltammetric signals. It has been stated, that the compounds can act as electrocatalysts — they are protonated and adsorbed at the surface of the electrode, after which the protonated forms of the compounds are irreversibly reduced, yielding their initial form and hydrogen. The experimental adsorption data obtained by measuring the differential capacity of the double layer, the zero charge potential, and the surface tension at the zero charge potential have established the adsorption processes underlying their electrochemical activity. The analytical application of the obtained voltammetric signals in the determination of these compounds in biological samples is also presented. This review concentrates on our own results in the context of general developments in the field.

Studies of a Mixed Adsorption Layer of Butan-1-ol and o-Toluidine on Mercury Electrode

2002 ◽  
Vol 67 (11) ◽  
pp. 1579-1588 ◽  
Author(s):  
Dorota Sieńko ◽  
Dorota Gugała ◽  
Jolanta Nieszporek ◽  
Joanna Jankowska ◽  
Jadwiga Saba
Keyword(s):  
Thermodynamic Analysis ◽  
Adsorption Layer ◽  
Supporting Electrolyte ◽  
Mercury Electrode ◽  
Interaction Constant ◽  
Repulsive Interaction ◽  
Surface Excess ◽  
Adsorption Parameters ◽  
Frumkin Isotherm ◽  
Adsorption Layers

The results of thermodynamic analysis of o-toluidine adsorption on a mercury electrode in the presence of various butan-1-ol amounts complete our previous studies on properties of mixed adsorption layers of toluidine isomers-butan-1-ol. The values of the relative surface excess Γ'°T obtained for o-toluidine show that adsorption of this compound decreases with increasing of butan-1-ol concentration. Analysis of adsorption parameters derived from the Frumkin isotherm indicates that in the presence of 0.33 M BuOH in 1 M NaClO4 with adjusted pH 3 as supporting electrolyte, ∆G0 values for o-toluidine are the highest and, at the same time, the strongest repulsive interaction occurs. In the presence of 0.11 M butan-1-ol, smaller values of ∆G0 for o-toluidine correspond to weaker repulsive interaction. Therefore the change of the Γ'°T value for o-toluidine as a function of butan-1-ol concentration is the result of mutual changes of ∆G0 and interaction constant A between adsorbate molecules.

A Comparative Study of Adsorption of Aliphatic Amines at a Gold Electrode

2005 ◽  
Vol 70 (12) ◽  
pp. 2027-2037 ◽  
Author(s):  
Teresa Łuczak
Keyword(s):  
Gibbs Energy ◽  
Comparative Study ◽  
Gold Electrode ◽  
Surface Coverage ◽  
Standard Gibbs Energy ◽  
Gold Surface ◽  
Experimental Dependence ◽  
Aliphatic Amines ◽  
Solvent Interactions ◽  
Amine Concentration

Adsorption of aliphatic amines (C1-C4) at the gold electrode was studied by tensammetry. It has been established that the experimental dependence between the gold surface coverage (Θ) and the bulk amine concentration (cA) fits satisfactorily both by the Frumkin and Flory-Huggins isotherms. The standard Gibbs energy of adsorption, ∆G°ad at Emax for Θ < 0.8 has been found to increase in the order methylamine < ethylamine < propylamine < butylamine. This is rationalised in terms of surface-adsorbate, adsorbate-adsorbate and adsorbate-solvent interactions.

scholarly journals Estimation of standard Gibbs energy changes of biotransformations

1991 ◽  
Vol 266 (22) ◽  
pp. 14440-14445
Author(s):  
M.L. Mavrovouniotis
Keyword(s):  
Gibbs Energy ◽  
Standard Gibbs Energy

Measurements and Theoretical Interpretation of Points of Zero Charge/Potential of BSA Protein

Langmuir ◽  
2011 ◽  
Vol 27 (18) ◽  
pp. 11597-11604 ◽  
Author(s):  
Andrea Salis ◽  
Mathias Boström ◽  
Luca Medda ◽  
Francesca Cugia ◽  
Brajesh Barse ◽  
...  
Keyword(s):  
Theoretical Interpretation ◽  
Zero Charge ◽  
Charge Potential ◽  
Zero Charge Potential
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