Grey Relational Analysis of Amine Inhibition of Mild Steel Corrosion in Acids

Abstract

Grey relational analysis makes use of relatively simple mathematical procedures to arrive at salient relationships in a complex system. It uses a relatively small amount of data and works with great variability in factors. Grey relational analysis was used to investigate the relationship between inhibitor structure and inhibitor performance for a series of amines of different structures in the corrosion of mild steel in acids. Results showed the molecular weight (MW), the negative of the logarithm of the dissociation constant (pKa), and the number of nitrogen donor atoms influenced inhibitor effectiveness in the active region. The number of NH bonds was an additional factor for inhibition in the passive region. Trends in these factors were rationalized in terms of adsorptive interactions between the inhibitor molecules and the substrate. Results conformed to findings in the literature and were verified by additional measurements using hexamine as the inhibitor.