Comparative studies on the corrosion inhibition characteristics of three different triazine based Schiff’s bases, HMMT, DHMMT and MHMMT, for mild steel exposed in sulfuric acid

The inhibition behavior of three different triazine based Schiff’s bases, HMMT, DHMMT and MHMMT for mild steel corrosion in sulphuric acid has been investigated using weight loss, electrochemical studies, SEM, spectroscopic studies and basic computational studies. The inhibition efficiency increased with increase in inhibitor concentration but decreased with rise in temperature and acid concentration in the case of these three inhibitors. The order of inhibition efficiency expected from the values of band energy is in good agreement with the results obtained from weight loss and electrochemical studies. Polarization studies indicated the mixed type behavior of these inhibitors. Field emission scanning electron microscopic studies revealed that inhibitors protect the metal surface by the forming a protective film through adsorption of inhibitor molecules. Keywords: Mild steel, Corrosion inhibition, Schiff’s base

Physicochemical studies on the inhibitive properties of a 1,2,4-triazole Schiff’s base, HMATD, on the corrosion of mild steel in hydrochloric acid

The efficiency of 4-(4-hydroxy-3-methoxy benzyledene amino)-4-H-1,2,4-triazole-3, 5-dimethanol, HMATD, as corrosion inhibitor for mild steel in 0.5 M HCl has been determined by weight loss measurements and electro analytical methods. The influence of various parameters such as temperature, inhibitor concentration on the efficiency has been studied. The electrochemical impedance spectroscopic measurements revealed the inhibition action of HMATD by reducing the charge transfer through metal solution interface. Polarization curves indicate the mixed type behaviour of HMATD. The inhibitor molecule functions by blocking the active sites on metal surface by adsorption and which obeys the Langmuir adsorption isotherm. Various kinetic and thermodynamic parameters have also been calculated. Keywords: Mild steel, EIS, Activation energy, Adsorption isotherm, SE

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