Portugaliae
Electrochimica Acta

Mentha Spicata irrigated by wastewater from the city of Settat (Morocco) was tested as corrosion inhibitor of aluminum in 1 M HCl using polarization method and weight loss measurements. The inhibition efficiency of mentha spicata oil was calculated and compared. We note good agreement between these methods. The results obtained showed that the tested inhibitor reduces the kinetic process of corrosion of aluminum. Its efficiency increases with the concentration and attained 83,01% at 1800 ppm. The effect of temperature on the corrosion behaviour of aluminum in 1M HCl was also studied in the range 283 K and 313 K. The thermodynamic data of activation were determined. The analysis of mentha spicata oil obtained by hydro-distillation using gas chromatography (GC) showed that the major components are carvone 57.11 % and limonene 27.77%.

The anodic dissolution of zinc electrodes in sodium chloride aqueous solution has been investigated experimentally. The effects of application of polarity reversal (PR), ultrasonic (US) enhancement, stirring, current density (CD), concentration and pH of the supporting electrolyte, and temperature of the bath were studied. The results revealed that application of PR increased the dissolution of Zn but the current was low. However, the application of US enhancement led to higher zinc dissolution accompanied with higher current efficiency (CE). The combination of US enhancement and stirring led to more dissolution of zinc. Increasing the current density and concentration of NaCl increased the dissolution of zinc and the current efficiency was almost constant. On the other hand, pH of the bath did not play a significant effect on the amount of the dissolved zinc or current efficiency. It was also observed that increasing the temperature from 10 oC to 40 oC led to a significant increase in the mass of the dissolved zinc and CE; but the increase of temperature from 40 oC to 50 or 60 oC, however, did not have a significant effect.

The main objective of this work is to study the behavior of copper corrosion in nitric acid medium (2 M) for the evaluation and comparison of the corrosive power of the essential oil of Thymus Satureoides. To do this, we used weight loss and polarization techniques. The results show that the recovery rate of copper corrosion decreases in the presence of the essential oil tested. In a second step, we performed tests on the major component of the oil and the results obtained showed that the activity of the essential oil of thyme is clearly not related to it’s major constituent. On the other hand, it is clear from this study that the inhibition efficiency increases with the concentration of inhibitors to reach 89.04% at 1200 ppm for the essential oil of thyme and 69.72% at 1600 ppm for borneol. The adsorption isotherm and the activation energy were also determined.

A different approach for protecting the aluminium in 1M HCl is done by strengthening the surface oxide film of aluminium with nickel titanate particles. Weight loss methods, open circuit potential measurements and polarization techniques are used to measure the corrosion behaviour of aluminium samples. The corrosion rate of nickel titanate deposited aluminium shows lower values compared to pure aluminium in HCl medium. The intermixing of aluminium oxide with nickel titanate enhances the corrosion resistance property of the aluminium oxide layer on the surface of aluminium and thereby reduces the coulombic and non-coulombic loss of metal.

The ultrasonic measurements of solutions of uranyl caprylate and laurate in a mixture of 50/50 benzene-dimethylsulphoxide (V/V) have been used to determine the critical micellar concentration, ultrasonic velocity and various acoustic parameters at different temperatures. The results confirm that there is a significant interaction between uranyl soaps and the mixed organic solvent molecules.The values of critical micellar concentration of uranyl caprylate and laurate are in good agreement with those obtained from conductivity measurements.