An insight about the interaction of Aryl Benzothiazoles with mild steel surface in aqueous HCl solution

Abstract

The arrival of organic moieties as corrosion inhibitors has expanded the research in the past few years which, as a result; involved different heteroatoms to be tested for their anti-corrosive potential. The presented research is focused on the synthesis of the aryl-substituted benzothiazoles namely 6-(4-Chlorophenyl) benzo[d]thiazol-2-amine (CBTA), 6-(p-tolyl) benzo[d]thiazol-2-amine (TBTA), and 6-(4-methoxyphenyl) benzo[d]thiazol-2-amine (MBTA), and investigation of their anti-corrosive behaviour on mild steel in 1 M HCl particularly. Here, gravimetric and electrochemical analyses have been employed to examine the tendency of benzothiazoles to safeguard mild steel. Corrosion impeding efficacies were found to follow a significant order; MBTA > TBTA > CBTA. Further, experimental analysis unveiled the effect of substituents on corrosion mitigating potential i.e., MBTA employed the ligation of methoxy group; an enhanced electron cloud thus providing a maximum shield. The addition of corrosion inhibitors in acidic solution brought an elevation in activation energy thus retarded the rate of corrosion. Surface analysis via atomic force microscopy (AFM) and X-ray photoelectron spectroscopy (XPS) confirmed the experimental results and attributed the presence of an adsorbed layer over mild steel surface thus providing protection from corrosion. Additionally, Quantum calculations such as density functional theory (DFT) and molecular dynamics (MD) provided an insight into the adsorption of inhibitors over mild steel at a molecular level.