Corrosion inhibition of copper in sulphuric acid by some nitrogen heterocyclic compounds

Abstract

Purpose

In this paper, the main aim is to study the influence of some nitrogen heterocyclic compounds, namely 2‐mercaptobenzimidazole (2‐MBI), 2‐mercaptobenzoxazole (2‐MBO) and 2‐mercaptobenzothiazole (2‐MBT) on the corrosion inhibition of copper in 0.5 M sulphuric acid.

Design/methodology/approach

Measurements were carried out in a three‐electrode cell that was connected to the corrosion measurement system using software for Tafel polarization. Impedance measurements were carried out at open circuit potential using an electrochemical interface and frequency response analyzer at frequencies from 100 kHz to 10 MHz.

Findings

For all the compounds, a consistent trend of increase in inhibition efficiency was observed as a function of concentration. The adsorption of all the compounds on to the copper surface in the acidic solution was found to obey the Langmuir Adsorption Isotherm. The values of activation energy and free energy of adsorption for all the compounds also were calculated. The Tafel polarization studies indicated that all the compounds were mixed inhibitors.

Research limitations/implications

In order to further the performance of heterocyclic compounds and also to identify their synergistic effects with some additives (such as surfactants) it is suggested that further research into the behaviour of these heterocyclic compounds with other metals be carried out.

Originality/value

The results of this paper can be used for acid descaling of copper in which suitable inhibitor systems with the highest efficiencies are required.

Citation

Shahrabi, T., Tavakholi, H. and Hosseini, M.G. (2007), "Corrosion inhibition of copper in sulphuric acid by some nitrogen heterocyclic compounds", Anti-Corrosion Methods and Materials, Vol. 54 No. 5, pp. 308-313. https://doi.org/10.1108/00035590710822161