Evaluation of 4-amidinophenyl-2,2′-bithiophene and its aza-analogue as novel corrosion inhibitors for CS in acidic media: Experimental and theoretical study

Abstract

Bichalcophene series namely 4-(2,2′-bithiophene-5-yl) benzamidine (MA-0944) and 6-(2,2′-bithiophene-5-yl) nicotinamidine (MA-0949) were evaluated as corrosion inhibitors for carbon steel (CS) in 1M HCl using nonelectrochemical and electrochemical techniques. The results revealed that the tested compounds are efficient corrosion inhibitors and their inhibition percentage (η %) reached 98.3% at 18×10−6M. The tested compounds are classified as mixed-type inhibitors. The adsorption of the investigated compounds corresponds to Langmuir adsorption isotherm. The surface morphology of the CS surface was analyzed using Attenuated Total Reflectance-infrared spectra (ATR-IR), and Atomic Force Microscopy (AFM). The inhibition property was further elucidated by theoretical approaches; quantum chemical calculation, Natural Bonding Orbital (NBO) analysis, Molecular Dynamic Simulation and Radial Distribution Function (RDF). The theoretical data support the experimental results.