Portugaliae
Electrochimica Acta

The influence of amino mercapto methyl triazole (AMMT) on the corrosion and hydrogen permeation of mild steel In 0.5 M H^SO^ and 1 M HC1 has been studied using weight loss measurements and various electrochemical techniques It is found to be more inhibitive in H2S0^. Potentiodynamic polarisation studies clearly prove that AMMT is a mixed type Inhibitor, but predominantly a cathodic inhibitor. Hydrogen permeation studies and AC impedance measurements indicate an improved performance of the compound "in H^SO^. The inhibitor of this type obeys Temkin adsorption isotherm.

In regard to the understanding of the silver electrodeposition process at carbon microelectrodes three different mechanisms have been proposed and its theoretical simulations are presented. A comparison between experimental and simulated voltammograms shows that several kinetic complexities occurs during the electrodeposition process.

Behaviour of the 1-Methyl-benzotriazole-. Benzimidazole- and l-iV//2-Benzimidazole-pentacyanoferrate (II), complexes in aqueous solution of 0.5M. NaCl04 at the platinum slectrode has been analysed by cyclic voltammetric measurements. The electrode-rate constant, k0, and the transfer coefficient, ana of the corresponding complexes have been estimated at different pH values.

Role of boric acid in the electrowinning process of nickel has been investigated through eye 1 icvo 11aminetry. Addition of boric acid to the nickel electrolyte has been found to decrease the hydrogen evolution, a side reaction at the cathode, as indicated by the features of a voltammetric peak for the oxidation of hydrogen codeposited in nickel. Control in alkalisation at the cathode vicinity has been discussed on the basis of the tendency of boric acid to release H+ ions through complex formation with nickel in the electrolyte. An attempt has also been made to fix up the amount of boric acid required on the basis of eye 1icvoltammograms generated.

The concept of the electrophoretic effect in electrolyte solutions and the way it has been presented in the literature is critically discussed.

Voltammetric studies were carried out on gold electrode to identify the oxidation products of elemental sulphur in alkali solutions. The oxidation of HS~ and S22~ is reversible followed by oxidation to sulphur which gets incorporated in the hidrous films on gold. Fitting occurs when the film break and the pitting susceptibility of gold increased with alkali concentration. On the sulphur covered gold surface, no oxygen reduction was observed and H2S evolved along with hydrogen.