Corrosion inhibition potential of a new corrosion inhibitor for mild steel in 1 M hydrochloric acid solution determined by weight loss technique, complemented with adsorption studies and DFT calculations

The use of corrosion inhibitors is one of the means employed to reduce corrosion in petroleum industry. There are a lot of technologies, for example, cathodic protection, organic coatings, application of first-class corrosion-resistant alloys that can be implemented to combat corrosion. However, film-forming inhibitors are still known to provide an unparalleled way to defend mild steel in acid environments. The inhibition efficiency of organic compounds strongly depends on the composition and chemical properties of the layer formed on the metal surface under certain experimental conditions. The corrosion inhibition efficiency of mild steel in 1 M hydrochloric acid environment by a new corrosion inhibitor namely 4-bromo-1-hydroxy-2-(((thiophen-2ylmethyl)imino)methyl)benzene (BHTB) was investigated by the weight loss technique. The experimental findings show that BHTB works quite well as a corrosion inhibitor of mild steel 1 M HCl solution. Efficient inhibition was achieved for BHTB at an optimum concentration of 500 pm and an immersion period of 5 h, however it decreases with rising temperature. The adsorption mechanism model of BHTB molecules fits quite well with the Langmuir adsorption model suggesting that BHTB adsorbs onto mild steel surface to form a protective layer. Quantum chemical calculations were based on density functional theory approaches which were utilized to understand the relationship between inhibition efficiency and molecular structure. To date, there is no report found in the literature regarding the use of BHTB as a corrosion inhibitor. Therefore, this study of corrosion inhibition of mild steel with BHTB was performed.