The Influence of Water Activity on Double Layer Parameters on the Interface Mercury/Chlorates (VII) in the Presence of Cysteine

Agnieszka Nosal-Wiercińska

doi:10.5562/cca2022

Abstract

The influence both the cysteine concentration and water activity on the double layer parameters on the interface mercury/ chlorates (VII) was examined. The adsorption parameters for the double layer were calculated from a double-layer differential capacity measurement extrapolated to zero frequency. The values of the relative surface excess increase of the cysteine concentration and chlorates (VII) solutions. It was found that the values of free adsorption energy and interactions constants, obtained from Frumkin and virial isotherms, depend on the supporting electrolyte concentration. The changes of determined parameters in the function of water activity water point at the participation of 4 ClO  ions in the adsorption processes, or that in the double layer the electrostatic interactions between the dipoles of 2 H O and cysteine compounds exist.(doi: 10.5562/cca2022)

Highlights

Cysteine ((2R)-2-amino-3-mercaptopropionic acid) is an endogenous aminoacid, which is formed in the reaction of a sulphur atom transfer from methionine to serine with the participation of ATP molecule
With the increase of cysteine concentration the hump on the curves Cd f E is decreasing and shifted towards the negative potentials (Figure 1a). Such behaviour reflects the removal of water molecules from electrode surface as a result of cysteine adsorption
The same effect is observed with the increase of chlorate (VII) concentration in the presence of all the cysteine concentrations examined

Summary

INTRODUCTION

Cysteine ((2R)-2-amino-3-mercaptopropionic acid) is an endogenous aminoacid, which is formed in the reaction of a sulphur atom transfer from methionine to serine with the participation of ATP (adenosine triphosphate) molecule. The path of the electrode reaction is determined by the form of mercury thiolates in the adsorbed state, which depends strongly on the pH of the solution.[14,15]. In the present paper the influence of cysteine and water activity on the double layer parameters on the interface mercury/ chlorates (VII) was examined. The choice of water as the medium, which as cysteine influences the double layer parameters on the interface mercury/ chlorates (VII) was determined by the specific water properties and the fact, that most of the chemical processes proceed in water environment. The potential of zero charge ( Ez ) was measured for each solution by the method of streaming mercury electrode,[24,25] with an accuracy of ± 0.1 mV. The values of the second virial coefficient B were calculated from the slopes of lines of the linear test of the virial isotherm and the corresponding G0 values were obtained from the intercepts of these lines with the axis log ' / c using the standard state of 1 mol·dm-3 in bulk solution and one molecule on the surface

RESULTS AND DISCUSSION

A Frumkin isotherm

CONCLUSIONS