Catalytic activity of thiourea and its selected derivatives on electroreduction of In(III) in chlorates(VII)

Abstract

It was found that thiourea, N-methylthiourea, N,N'-dimethylthiourea and N-allylthiourea accelerate the electroreduction process of In(III) ions in chlorates(VII). These substances are adsorbed on mercury from chlorates(VII). The relative surface excesses of thiourea and its derivatives increase with the increase of their concentrations and electrode charge. After adding thiourea, N-methylthiourea, N,N'-dimethylthiourea and N-allylthiourea to the solution an acceleration of the electroreduction process of In(III) ions occurs. This process depends on two factors: the adsorption of an accelerating substance on mercury and on the formation of complexes between a depolarizer and an accelerating substance on the electrode surface. The equilibrium of this complexing reaction determines the magnitude of the catalytic effect.© Versita Warsaw and Springer-Verlag Berlin Heidelberg.

Electroreduction of Bi(III) Ions at a Cyclically Renewable Liquid Silver Amalgam Film Electrode in the Presence of Methionine

“…The catalytic effect of metal cation reduction according to the “ cap – pair ” mechanism includes both chemical reactions and heterogeneous charge transfer processes of active complexes on the electrode surface. The surface formation of active complexes within the electrode double layer with the studied metal cations is a plausible mechanism for zinc(II) [ 2 , 3 ], cadmium [ 4 ], indium(III) [ 5 ] and bismuth(III) ion reduction [ 6 , 7 ], while the complexation of europium(III) ions is assumed to proceed in the bulk of the solution as well [ 8 ].…”

Electroreduction of Bi(III) Ions in the Aspect of Expanding the ”Cap – Pair” Effect

“…The mechanism for the catalytic effect of metal cations electroreduction under "cap-pair" conditions, includes both chemical reactions and heterogeneous processes of charge transfer between the electro-active particle of the complex and the depolarised working electrode. The formation of electroactive complexes with depolarisers is possible both in the adsorption layer for zinc(II) ions [18][19][20], cadmium [21] indu(III) [22,23] and bismuth(III) [24][25][26][27][28][29], and outside the layer for europium(III) ions [30]. The goal of this current paper was to collect and summarise studies on the kinetics and mechanism of action for selected organic substances on the electroreduction of Bi(III) ions in chlorate(VII) solutions in terms of expanding the interpretation of the "cap-pair" effect mechanism.…”

Influence of Mixed 6-Thioguanine-Nonionic Surfactant Adsorption Layers on Kinetics and Mechanism of Bi(III) Ion Electroreduction

“…Knowledge of organic substance effects on the electrode reaction rate is of significant importance in the elaboration of technological or pharmacological characteristics. It was found that the ability of the organic substance, undergoing adsorption on the electrode, to form complexes with the depolarizer in the near-electrode layer and location of the reduction potential of the depolarizer in the area of labile adsorption equilibrium of the organic substance [1][2][3]. A significant effect of activity of water and some polarographically active amino acids on the mechanism and kinetics of Bi(III) ion electroreduction [4,5] was proven which developed the interpretation of the "cap-pair" effect mechanism.…”