The impact of halogen substitution on the corrosion inhibition of imidazothiazole derivatives for mild steel in corrosive media (Part A)

Abstract

Our research aims to investigate the impact of halogens on the effectiveness of corrosion inhibitors for mild steel in a 1 M HCl solution, employing a holistic approach. Through complementary studies, we will elucidate the corrosion inhibition mechanism by examining neutral, protonated, and complex forms of inhibitors using advanced computational and statistical methods. This preliminary study consists of evaluating the effectiveness of the first two imidazothiazole derivatives by weight loss tests (WL) and electrochemical techniques. This research unveils that the inhibitors, namely 6-(4-fluorophenyl)imidazo[2,1-b]thiazole-5-carbaldehyde (Imid-F) and 6-(4-chlorophenyl)imidazo[2,1-b]thiazole-5-carbaldehyde (Imid-Cl), exhibit mixed-type inhibition behavior, and their efficiency in preventing corrosion is halogen-dependent. This inhibition efficiency improved with decreasing temperature and increasing inhibitor concentration, reaching 86% (Imid-F) and 90% (Imid-Cl) at 303 K and 1×10−3 M, respectively. Both chemicals' adherence may be described using the Langmuir adsorption isotherm model. Furthermore, scanning electron microscopy (SEM) confirmed the inhibitors were successfully deposited. The results obtained from the experimental and theoretical analyses suggest that the efficiency of the two halogenated imidazothiazoles follows the order: (Imid-Cl) > (Imid-F).