Thioamidines as novel class of corrosion inhibitors

Authors: Ajmal, M.; Rawat, J.; Quraishi, M.A.

Source: British Corrosion Journal, Volume 34, Number 3, March 1999 , pp. 220-224(5)

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Abstract:

Four nitrogen substituted thiobisformamidines – phenyl thiobisformamidines (PTBF), tolyl thiobisformamidines (TTBF), anisidyl thiobisformamidines (ATBF), and 4-chlorophenyl thiobisformamidines (CPTBF) – were synthesised and their corrosion inhibiting behaviour for mild steel in 1M, 3M, and 5M HCl was studied. The optimum concentration of these compounds for maximum inhibition efficiency was determined by weight loss methods. All the investigated thiobisformamidines gave more than 95% inhibition in the presence of 1M HCl, and CPTBF showed the best inhibition efficiency (98% in 5M HCl). Potentiodynamic polarisation studies revealed that all the tested compounds are of mixed inhibitor type. The adsorption of these compounds from the acid solution obeyed Temkin's adsorption isotherm. All the inhibitors were able to reduce hydrogen permeation through the steel surface and their performance was enhanced by the addition of iodide ions. Electron impedance spectroscopic studies were also carried out in order to understand the mechanism of inhibition. Auger electron spectroscopic analysis confirmed that the adsorption of these compounds on the surface of the mild steel occurs through nitrogen and sulphur atoms.

Document Type: Regular Paper

DOI: http://dx.doi.org/10.1179/000705999101500897

Affiliations: The Corrosion Research Laboratory, Department of Applied Chemistry, Faculty of Engineering and Technology, Aligarh Muslim University, Aligarh (UP), 202002, India

Publication date: 1999-03-01

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