Electrochemical studies with tin electrodes in citric acid solutions

The role of pH in corrosion inhibition of tin using the proline amino acid: theoretical and experimental investigations

Herein, the effect of a mediums' pH on the interfacial interactions between proline (Pro) amino acid and tin metal was studied. In this work, acidic and near-neutral pH values were considered. DFT-based calculations and Monte Carlo simulations were carried out in the aqueous phase to understand the role of pH in Pro/tin interactions. To confirm this role in terms of inhibition efficiency, the CC and AC electrochemical techniques were used. Based on the calculated parameters, it was outlined that the partially protonated Pro form exhibits significant affinity to interact with tin metal in near-neutral media. However, in acidic media, its affinity is decreased, whereas the full protonated form was found to be solvated in the solution and its interaction with the tin surface was not favorable. These findings indicated that the inhibition capability of Pro for tin could be better in near-neutral media than in acidic media. This expected behavior was confirmed experimentally, wherein an inhibition effectiveness of around 65% was obtained for Pro at pH 5, and 16% was observed at pH 2. Additionally, the results highlight the capability of employing computational studies to predict the prevention efficiency of anti-corrosion compounds by varying the solution pH.

Herein, the effect of a mediums' pH on the interfacial interactions between proline (Pro) amino acid and tin metal was studied.

Early Stages of Film Formation and Surface Growth on Tin Electrodes at Bicarbonate Medium: a Modelistic Approach

A modelistic approach of the early stages of film formation and surface growth on tin electrodes at bicarbonate medium under dynamic conditions is presented. The modelistic treatment was applied to both anodic and cathodic processes. In order to organise the paper, the potential interval of interest was divided into two potential windows, each one involving one of the anodic peaks and their corresponding cathodic counterparts. The Müller–Calandra model (also known as the layer-pore resistance model) was considered suitable to interpret the film growth processes occurring during the positive scan. A derivation of the former, developed by Devilliers et al., which take into account the conductive electrical nature of the surface compound, was applied to explain the reduction of the film formed within the first potential window. On the other hand, it was verified that the use of a simple model to interpret the cathodic process occurring at the second potential window was not possible due to the complex nature of the process. In this case, a mixed control kinetics was proposed and the current was considered as the sum of two contributions. In order to complement the description and specially to determine the role of diffusion and mass transport in film formation, rotating disk measurements were also carried out.