Adsorption and corrosion inhibition performance of multi-phytoconstituents from Dioscorea septemloba on carbon steel in acidic media: Characterization, experimental and theoretical studies

The adsorption and corrosion inhibition performance of the water phase and organic phase extracts from Dioscorea septemloba on carbon steel have been carried out in 1 M HCl solutions. Extracts characterization was accomplished by NMR spectroscopy and the generic carbohydrate test. Electrochemical techniques and gravimetry were utilized for the evaluation of corrosion inhibition behaviors. 3D surface measurement instrument, SEM, and FT-IR were used to examine the surface properties of carbon steel coupons after full immersion in 1 M HCl solutions without and with the extracts. Quantum chemical calculation (QCC) and molecular dynamics simulation (MDS) were used to predict and describe the electronic and adsorption properties of some characterized compounds in the extracts. Both extracts exhibited similar corrosion inhibition behaviors acting as mixed-type inhibitors and having their efficiencies dependent on concentration and temperature. Time-dependent corrosion evaluation showed that the inhibition efficiencies of the extracts were improved with time. Low surface roughness data were recorded for the extracts by 3D surface measurements and the results were consistent with the observations from SEM micrographs and FT-IR spectra. Computational parameters obtained from QCC and MDS were used to predict the adsorption behavior of some characterized compounds from the extracts.