No abstract

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.

The corrosion behaviour of pure Al, Cu, 1018 carbon steel and 304 type stainless steel in Canola biodiesel during 528 hours has been evaluated by using electrochemical techniques. Techniques include open circuit potentials (OCP), electrochemical noise (EN) and electrochemical impedance spectroscopy (EIS) measurements at room temperature. These tests were complemented by scanning electronic microscopy, X-ray diffraction, infrared spectroscopy and gas mass chromatography analysis. Results have shown that carbon steel had the highest corrosion rate whereas Cu had the lowest corrosion rate. EN measurements indicated that 304 type stainless steel was moderately susceptible to pitting corrosion, whereas the rest of the metals were susceptible to either mixed or uniform type of corrosion. This was due to the degradation of the biodiesel as observed in an increase in its density, viscosity, acidity and water content at the end of the test.

No abstract

A tin-containing metallic complex derived from Curcuma longa, bis[1,7-bis(4-hydroxy-3-methoxyphenyl)-1,6-heptadiene-3,5-dionato-κO,κO ′ ]bis(butyl), has been obtained and used as a green corrosion inhibitor for carbon steel in 0.5 M sulfuric acid by using weight loss, electrochemical techniques, and the Density Functional Theory. It was found that the obtained metallic complex greatly decreases the steel corrosion rate by adsorption according to a Frumkin model in a weak, physical type of adsorption. Inhibitor efficiency increased with its concentration, and it acted as a mixed type of inhibitor. Results were supported by quantum-chemical research in order to examine the relationship between structural and electronic properties and the inhibitor efficiency.