An investigation of mild steel corrosion inhibition in hydrochloric acid medium by environment friendly green inhibitor

International audienceThe inhibitive effect of Thymus algeriensis plant extract (TEA) on the corrosion of mild steel in 1.0 M HCl solution has been investigated by weight loss measurement as well as potentiodynamic polarization and electrochemical impedance spectroscopy (EIS) techniques. The presence of Thymus algeriensis plant extract reduces remarkably the corrosion rate of mild steel in acidic solution. The effect of temperature on the corrosion behavior of mild steel was studied in the range of 313-343 K. The results from this corrosion test clearly reveal that the extract behaves as a mixed type corrosion inhibitor with the highest inhibition at 1.0 g/L. The Nyquist plots showed that increasing TEA concentration, charge-transfer resistance increased and double-layer capacitance decreased, involving increased inhibition efficiency. Linearity of Temkin isotherm adsorption

Chemical composition, antioxidant and anticorrosive activities of Thymus Algeriensis.

International audienceKnown therapeutic applications of medicinal plants were made of them an alternative to synthetic compounds. In this situation, the present study was designed to give more knowledge and helping to exploit the leaves of Thymus algeriensis by determining the chemical composition of its essential oil, the phenolic content of the aqueous extract and evaluate the antioxidant and anticorrosive activity. The essential oil was characterized by Geranyl acetate (80.8%) as mainly compound. The aqueous extract has exhibited a moderate antioxidant activity against free radical DPPH. On the other hand, this work describes the successful performance of T. algeriensis as an eco-friendly corrosion inhibitor for acidic media. The corrosion inhibiting effect of the extract and the essential oil of T. algeriensis (TAE & TAO) on mild steel in 0.5 M H 2 SO 4 solution was investigated by electrochemical studies in the presence of different concentrations of TAE & TAO ranging from 0.25 g/L to 2 g/L. Potentiodynamic polarization showed that TAE and TAO behaves as mixed type inhibitors. Nyquist plots show that the efficiency of inhibition increases with increasing concentration of T. algeriensis and the increased charge transfer resistance

Synergistic Combination Effect of Salvia officinalis and Lavandula officinalis on the Corrosion Inhibition of Low-Carbon Steel in the Presence of SO42−- and Cl−-Containing Aqueous Environment

The corrosion inhibition of low-carbon steel in 1 M H2SO4 and HCl solutions by the admixture of Salvia officinalis and Lavandula officinalis essential oil extracts was studied through potentiodynamic polarization analysis, coupon measurement and optical microscopy. The carbon steel undergoes severe surface deterioration in H2SO4, while the morphology of the steel from HCl showed selective deterioration with numerous corrosion pits in the absence of the oil extracts. The extracts performed effectively in the acid media with optimal inhibition efficiency of 86.92 and 96.90% in H2SO4, and 84.68 and 97.59% in HCl from potentiodynamic polarization and coupon analysis. The oil extract displayed anodic inhibition properties in H2SO4 due to surface coverage of the steel and cathodic inhibition in HCl due to selective precipitation of extract molecules. Thermodynamic calculations show the extracts adsorbed onto the steel surface, effectively suppressing the corrosion reactions through chemisorption mechanism according to the Langmuir, Frumkin and Freundlich adsorption isotherms