The use of Rosmarinus officinalis as a corrosion inhibitor for 1018 carbon steel in 0.5 M H 2 SO 4 has been evaluated by using weight loss, potentiodynamic polarization curves and electrochemical impedance spectroscopy techniques at 25˚. Inhibitor concentrations were included within the range between 0 and 1000 ppm C using three extract solvents, namely acetone, hexane and methanol. Results have shown that Rosmarinus officinalis is a good corrosion inhibitor with its efficiency increasing with the concentration. The best efficiency was obtained with the hexanic extract. The passivating film properties of the steel were improved by the presence of flavonoids in the extract.

The extract of Prunus persica (P. persica) leaves was studied as a green corrosion inhibitor (GCI) of AISI 1018 steel in 0.5 M H 2 SO 4 at 25 °C. The corrosion inhibition efficiency (CIE) was established by the weight loss, potentiodynamic polarization curves (PPC) and electrochemistry impedance spectroscopy (EIS) techniques. The results showed that the IE was directly proportional to the inhibitor concentration, obtaining a maximum IE at 600 ppm (97 %) with a residence time of 6 h. The analysis of the electrochemical parameters from the polarizations curves confirmed that the P. persica extract behaved as a mixed-type GCI with cathodic predominance. The micrographs confirmed negligible damage on the steel surface when protected with the P. persica as GCI against the corrosive medium. The GC-MS analysis detected a high concentration of α-Tocopherol (vitamin E) and β-Sitosterol among the phytochemicals present in the P. persica extract. Lactuca sativa (L. sativa) and Artemia salina Leanch (A. salina) were used as bioindicators of possible toxic effects exerted by the GCI, finding that the germination of seeds and radicle development of L. sativa were little affected (30 % of inhibition for hypocotile develop) by the P. persica extract at 600 ppm. However, the GCI turned to be harmless for the second bioindicator (A. salina).

p. Medellín, Colombia Universidad de Medellín * Artículo escrito en el marco del proyecto de investigación Estudio de tejidos vegetales como adsorbentes naturales para la remoción de colorantes en medio líquido desarrollado en el año 2016 con recursos del Programa de

The Equisetum arvense extract was prepared by the maceration technique and experimentally tested as a corrosion inhibitor of A36 steel in 0.5 M sulfuric acid at room temperature. The corrosion resistance was estimated by the determination of the polarization curves, linear polarization resistance (LPR) and electrochemical impedance spectroscopy (EIS). In order to study the effect of the Equisetum arvense extract on the superficial morphology of metal, scanning electronic microscopy (SEM) was used. The results indicated a decrease of about two orders of magnitude in the corrosion rate, an increase in polarization resistance and a greater efficiency of inhibition by increasing the concentration of extract. The corrosion mechanism was mainly controlled by charge transfer from metal to the environment through the double electrochemical layer. The SEM images corroborated the results obtained in the corrosion tests, at higher concentration of extract less metal surface damage was observed.

The methanolic extract of Peumus boldus (P. boldus) has been studied as a potential green corrosion inhibitor for carbon steel in 0.5 M H 2 SO 4 using gravimetric, potentiodynamic polarization and electrochemical impedance spectroscopy tests at 25, 40 and 60°C, and concentrations of 0, 0.1, 0.3, 0.5, 0.7 and 1.0 g/L. Results indicate that P. boldus is physically adsorbed onto the steel surface and acts as a mixed corrosion inhibitor of carbon steel corrosion. The data fitted best to the Temkin adsorption isotherm. The inhibition efficiency of P. boldus extracts was observed to increase with increasing its concentration but decreases on increasing the test temperature. The inhibitive effect is attributed to the presence of vitamin E, Limonene and eucalyptol in the extract.