Methionine derivatives as green corrosion inhibitors: Review

This review exposed the inhibitory effect of methionine as green compound and its derivatives. The efficacy of these kind of molecules is related to two combined groups: amine and carboxylic acid as well as the presence of sulphur atom. Search on Scopus showed that a hundred publications in various aggressive solutions as HCl, H2SO4, H3PO4, HNO3, NaCl. The corrosion of iron, aluminium, lead, copper, nickel, tin … can be retarded using methionine derivatives which adsorbed on several kind of adsorption isotherms depending on the nature of metal/solution interface

Inhibition Effect of 6-bromo-3-nitro-2-phenylimidazol[1,2-α] pyridine on the Corrosion of C38 Steel in H2SO4 Solution

The inhibition effect of 6-bromo-3-nitro-2-phenylimidazol[1,2-α] pyridine (BNPP) on the corrosion of C38 steel in 0.5 M H2SO4 was studied by weight loss , electrochemical methods. The results showed that BNPP was a good inhibitor in 0.5 M H2SO4 and this adsorption obeyed the Langmuir adsorption isotherm. The results obtained from the different corrosion evaluation techniques are in good agreement. Polarization curves showed that BNPP acted as a mixed-type inhibitor in sulfuric acid. The effect of the temperature on the corrosion behavior with addition of 10-3M of the inhibitor was studied in the temperature range 298-328 K, and the thermodynamic parameters were determined and discussed. Quantum chemical approach, using the density functional theory (DFT), was applied in order to get better understanding about the relationship between the inhibition efficiency and molecular structure of BNPP. The theoretical results were found to be consistent with the experimental data

Inhibitory effect of Acacia hamulosa methanolic extract on the corrosion of mild steel in 1 M hydrochloric acid

The flora of Saudi Arabia comprises about 18 species of Acacia species including Acacia hamulosa Benth. The methanolic extract of the flowering tops of A. hamulosa was tested for its radical scavenging activity toward 2,2-diphenyl-1-pricylhydrazyl (DPPH) radical and the activity was compared with L-ascorbic acid, quercetin and Trolox as standards. The total phenolic content was determined using Folin-Ciocalteu method. In addition the methanolic extract has been evaluated as a corrosion inhibitor for steel in 1 M HCl solution by means of weight loss measurements, potentiodynamic polarization, electrochemical impedance spectroscopy (EIS). Tafel polarization study revealed that extract of Acacia hamulosa acts as a cathodic type inhibitor. Inhibition was found to increase with increasing concentration of the extract of Acacia hamulosa. Values of inhibition efficiency calculated from weight loss, Tafel polarization curves, and EIS are in good agreement. The effect of temperature on the corrosion behaviour of mild steel in 1 M HCl with addition of extract was also studied and thermodynamic parameters were determined and discussed.               KEY WORDS: Acacia hamulosa, Extract, Polyphenols, Antioxidant corrosion, Electrochemical study Bull. Chem. Soc. Ethiop. 2018, 32(2), 323-335.DOI: https://dx.doi.org/10.4314/bcse.v32i2.1