Assessment of methylene blue as a corrosion retardant for carbon steel in hydrochloric acidic solutions

Purpose The purpose of this study is to evaluate the corrosion retardation properties of methylene blue on carbon steel in hydrochloric acid solutions. Design/methodology/approach The corrosion inhibition property of methylene blue on carbon steel was investigated by hydrogen evolution technique (gasometric technique) and weight loss measurements at 303 K and 333 K in hydrochloric acid solutions. Findings The results revealed that methylene blue inhibited the corrosion carbon steel, and the inhibition efficiency was temperature dependent. The maximum inhibition efficiencies were 88% at 303 K and 79.2% at 333 K. The corrosion data was consistent with the Langmuir adsorption isotherm which posits that the methylene blue molecules adhered to the metal substrate. The corrosion kinetics followed the first-order kinetic reaction equation. The activation energy (Ea) values ranged from 45.6 to 81.7 kJ/mol and indicated physical adsorption. Originality/value This paper provides new information on the possible application of methylene blue as corrosion inhibitor for carbon steel.