Inhibitive effect of bithiophene carbonitrile derivatives on carbon steel corrosion in 1 M HCl solution: experimental and theoretical approaches

Abstract

The effect of [2,2′:5′,2″-terthiophene]-5-carbonitrile and its derivatives on carbon steel surface in 1 M HCl solution was deliberated at (25 °C) using weight loss technique in addition to electrochemical techniques such as electrochemical frequency modulation, potentiodynamic polarization, and electrochemical impedance spectroscopy. Results gained from all techniques employed are in good coincidence with each other. Results illustrate that [2,2′:5′,2″-terthiophene]-5-carbonitrile is considered as the best inhibition efficiency at 18 × 10−6 M additive concentration. Efficiency was found to rise with rising concentration and decrease with rising temperature. Adsorptions of organic derivatives on the carbon steel surface follow the Langmuir isotherm. Polarization studies showed that inhibitors are mixed type. From weight loss technique at different temperature data, we calculated the thermodynamic functions of adsorption process and analyze the mechanism between inhibitor and carbon steel surface. The morphology of steel surface was estimated by using SEM, EDX, AFM, and FT-IR. The inhibition performance had been discussed also using theoretical study by quantum chemical calculations and molecular dynamic simulation. [Figure not available: see fulltext.].