Development of passive film and enhancement of corrosion protection of mild steel in hydrochloric acid through the synergistic interaction of 2-amino-4-methyl benzothiazole (AMBT) and (E)-2-methylbenzo[d]thiazol-2-yl) imino-4-methyl) phenol (MBTP)

2-amino-4-methylbenzothiazole (AMBT) and one of its derivatives (E)-2-methylbenzo[d]thiazol-2-yl)imino-4-methyl) phenol (MBTP) were used as synergistic pair for the protection of mild steel in 0.5 M HCl. The combination of inhibitors, AMBT-MBTP, adsorbs on electrode surface through chemical and physical means. The antagonistic interaction was more pronounced on higher temperature, and an inhibition efficiency of 92% was recorded at 313 K and 93% at 303 K. The formation of protective film of AMBT-MBTP combination is further evidenced by SEM and AFM images. The process of adsorption followed Langmuir isotherm model and corresponding thermodynamic activation parameters were also calculated and discussed. Corrosion inhibition efficiency and the reaction kinetics of synergistic pair were evaluated by electrochemical impedance spectroscopy (EIS), potentiodynamic polarization and weight loss measurements. H-bonding interaction and resulting enthalpy change and reactivity descriptors were computed for correlating the corrosion inhibition efficiency and molecular structure by B3LYP/6-31G∗ level of Density Functional Theory (DFT). Keywords: Mild steel, Acid corrosion, Organic inhibitor

Corrosion protection of mild steel in hydrochloric acid solution through the synergistic of alkylbenzimidazoles and semicarbazide pair – Electroanalytical and computational studies

Hydrogen bonded interaction and synergistic effect on the corrosion protection properties of alkyl benzimidazoles and semicarbazide pair on mild steel in hydrochloric acid at 303, 308 and 313 K have been studied by polarization, electrochemical impedance spectroscopy, adsorption, surface studies and basic computational calculations. The inhibition efficiencies and the global chemical reactivity relate to total energy, EHOMO, ELUMO and gap energy (ΔE). Semicarbazide interacts with alkyl benzimidazoles up to an average bond length of 1.9296 Å. This interaction may be due to the formation of a hydrogen bond between semicarbazide and alkyl benzimidazoles. This synergistic interaction offer extended inhibition efficiency toward mild steel in hydrochloric acid. The corrosion inhibition efficiencies and the global chemical reactivity relate to total energy, EHOMO, ELUMO and gap energy (ΔE)

Synergistic interaction of 2-amino 4-methyl benzothiazole (AMBT) and benzotriazole (BTZ) offers excellent protection to mild steel exposed in acid atmosphere at elevated temperatures: Electrochemical, computational and surface studies

The synergistic interactions and corrosion protection properties of 2-amino 4-methyl benzothiazole, (AMBT) and 1, 2, 3-benzotriazole (BTZ) have been studied for mild steel in HCl at elevated temperatures. The extent of synergistic interaction increases with temperature. The methods of study include the conventional weight loss studies, computational screening, surface characterization and electrochemical studies. Quantum chemical approach was used to calculate some electronic properties of the molecules and to ascertain the synergistic interaction, inhibitive effect and molecular structures. The corrosion inhibition efficiencies and the global chemical reactivity relate to parameters like total energy, EHOMO, ELUMO and gap energy (ΔE). Condensed atom Fukui functions also calculated using DFT at B3LYP/6-31G* level, and were found to be correlating with the experimental results. Keywords: Mild steel, AMBT, BTZ, Weight loss, EIS, Polarizatio