Adsorption and Oxidation of Thiosulfate on the Platinum Electrode in a Slightly Alkaline Medium

2000 ◽  
Vol 65 (1) ◽  
pp. 1-8 ◽  
Author(s):  
Tomáš Loučka
Keyword(s):  
Alkaline Medium ◽  
Oxidation Reaction ◽  
Open Circuit Potential ◽  
Platinum Electrode ◽  
Adsorbed Layer ◽  
Open Circuit ◽  
Adsorbed Hydrogen ◽  
Oxidation Number ◽  
Hydrogen Electrode ◽  
Layer Region

The aim of this research was to study the oxidation and reduction of the adsorbed thiosulfate on the platinum electrode in a slightly alkaline medium. The adsorption was performed at the open circuit conditions. The reduction of the adsorbed layer in the hydrogen region is slower in a slightly alkaline medium than in acid. The mechanism of reduction and oxidation of adsorbed molecules is probably the same. The nonstationary currents measured in presence of thiosulfates showed that the change in the oxidation number does not take place during the adsorption in the double layer region. In the hydrogen region, thiosulfate replaces the adsorbed hydrogen while beeing reduced. Nonstationary currents at higher concentrations of thiosulfate indicate the presence of more layers on the electrode. Upon reaching higher concentrations of thiosulfate the oxidation reaction takes place between thiosulfate in solution and adsorbed product of its reduction. The open circuit potential of the platinum electrode measured in a thiosulfate solution was 0.780 and 0.783 V against the hydrogen electrode in the same solution.

scholarly journals Potentiometric Response of Ag/AgCl Chloride Sensors in Model Alkaline Medium

2018 ◽  
Vol 2018 ◽  
pp. 1-12 ◽  
Author(s):  
Farhad Pargar ◽  
Hristo Kolev ◽  
Dessi A. Koleva ◽  
Klaas van Breugel
Keyword(s):  
Alkaline Medium ◽  
Open Circuit Potential ◽  
Dynamic Equilibrium ◽  
Chloride Concentration ◽  
Chloride Content ◽  
Cementitious Materials ◽  
Open Circuit ◽  
Potentiometric Response ◽  
Before And After ◽  
The Stability

The stability and reproducibility of an Ag/AgCl sensors’ response in an alkaline medium are important for the application of these sensors in cementitious materials. The sensors’ response, or their open circuit potential (OCP), reflects a dynamic equilibrium at the sensor/environment interface. The OCP response in an alkaline medium is affected by the presence of hydroxide ions. The interference of hydroxide ions leads to inaccuracies or a delay in the sensors’ response to a certain chloride content. In this article, the potentiometric response (or OCP evolution) of the chloride sensors is measured in model solutions, resembling the concrete pore water. The scatter of the sensors’ OCP is discussed with respect to the interference of hydroxide ions at varying chloride concentration in the medium. The deviation of the sensor’s response from its ideal performance (determined by the Nernst law) is attributed to dechlorination of the AgCl layer and the formation of Ag2O on the sensor’s surface. Results from the surface XPS analysis of the AgCl layer before and after treatment in alkaline medium confirm these observations in view of chemical transformation of AgCl to Ag2O.

Adsorption and Oxidation of Thiosulfate on a Platinum Electrode in Acid Solution

1998 ◽  
Vol 63 (1) ◽  
pp. 20-30 ◽  
Author(s):  
Tomáš Loučka
Keyword(s):  
Open Circuit Potential ◽  
Platinum Electrode ◽  
Supporting Electrolyte ◽  
Open Circuit ◽  
Adsorbed Layers ◽  
Adsorbed Substance ◽  
Adsorbed Sulfur ◽  
Adsorption Desorption ◽  
Supporting Electrolyte Solution ◽  
Thiosulfate Concentration

The adsorption of thiosulfate on a platinum electrode was measured at the open circuit potential. A monolayer of the adsorption products covers the electrode at lower thiosulfate concentrations. The charge used up during the reduction of the monolayer roughly corresponds to 0.5 electron per surface site (e.p.s.), the charge used up during the oxidation of the monolayer after reduction corresponds approximately to 4 e.p.s. Multiple adsorbed layers, which are presumably constituted mainly by adsorbed sulfur, build up at higher thiosulfate concentrations. The amount of the adsorbed substance increases with increasing thiosulfate concentration and time of adsorption. Desorption from the surface coated by multiple layers can take place in supporting electrolyte solution. The build-up of multiple adsorbed sulfur layers also takes place during adsorption from solutions of colloidal sulfur.

scholarly journals Diagnostic capabilities of monitoring of redox potential in blood plasma of lung transplant patients

2019 ◽  
Vol 11 (2) ◽  
pp. 128-140 ◽  
Author(s):  
A. K. Evseev ◽  
E. I. Pervakova ◽  
I. V. Goroncharovskaya ◽  
E. A. Tarabrin ◽  
M. Sh. Khubutiya ◽  
...  
Keyword(s):  
Blood Plasma ◽  
Lung Transplant ◽  
Open Circuit Potential ◽  
Clinical Laboratory ◽  
Platinum Electrode ◽  
Open Circuit ◽  
Transplant Patients ◽  
Laboratory Test Results ◽  
Diagnostic Capabilities ◽  
In Blood Plasma

Introduction. Monitoring of redox potential (platinum electrode open circuit potential) in biological media (serum, blood plasma) is one of the promising methods for diagnosing and predicting the development of complications in patients in the early post-transplantation period. The study of the diagnostic capabilities of this technique in patients after lung transplantation is highly relevant.The objective was to assess the diagnostic and prognostic capabilities of monitoring platinum electrode open circuit potential in blood plasma of lung transplant patients.Material and methods. The data obtained at monitoring of platinum electrode open circuit potential in blood plasma and clinical laboratory test results of 14 patients after double lung transplantation surgery were analyzed. The platinum electrode open circuit potential value in the blood plasma was measured by the potentiometric method.Results. The study demonstrated the differences in the dynamics and values of platinum electrode open circuit potential in the blood plasma between the lung transplant patients with a favorable outcome and those with a fatal outcome. Wave-like segments on the relationship curves of the platinum electrode open circuit potential in blood plasma to time coincided with inflammatory markers (C-reactive protein, stab neutrophils, erythrocyte sedimentation rate) activation. Statistically significant correlations between platinum electrode open circuit potential values in blood plasma and clinical laboratory test results were revealed.Conclusion. The informative value and diagnostic capabilities of the technique of the platinum electrode open circuit potential measurement in blood plasma of lung transplant patients have prospects of using its results as a criterion for assessing the patient’s condition and improving the quality of therapy. 

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