The present work proposes the study of the extract of Senecio anteuphorbium (SA) as green corrosion inhibitor. This inhibitory effect of SA extract on the corrosion of S300 steel in hydrochloric acid 1 M has been evaluated by using the potentiodynamic polarization and electrochemical impedance spectroscopy. From the outcome of the polarization curves, SA extract acts as mixed-type inhibitor. The inhibition efficiency increased with the extract concentration increase to achieve a maximum of 91% at 30 mg/L. The adsorption of the inhibitor on the steel surface follows Langmuir isotherm and the values of activation energy suggested that the adsorption of inhibitor is a physical–chemical adsorption. Kinetic parameters such as enthalpy, activation energy and entropy were determined and discussed. The surface morphology of steel was observed before and after adding inhibitor by Fourier transform infrared spectroscopy. The changes in contact angles identified the formation of the protective film. Scanning electron microscopy and energy-dispersive X-ray revealed the adsorption of the same organic compounds of the extract on the interface metal/solution.

In this study, a self-organized nanotubular titanium dioxide (TiO₂) array was successfully produced by anodizing pure titanium in a mixture of glycerol, distilled water (8 vol.), and ammonium fluoride using a dual electrode system. The size control and distribution of the nanopores were performed in a DC voltage range varying from 30V to 60V. The diameter of TiO₂ nanopores varies from 59 to 128nm depending on the anodizing voltage. Energy-dispersive X-ray spectroscopy (EDX) analysis reveals that the as-prepared films are essentially composed of TiO₂. According to the X-ray diffraction (XRD) and Raman spectroscopy analysis, the nanotubular arrays of TiO₂ annealed at 600C for 2 hours are composed of a phase mixture of anatase and rutile. Mott-Schottky analysis showed that the TiO₂ nanotubes are consistent with an n-type semiconductor with a donor density of about 10¹⁷cm^-3. Preliminary results on the photocatalytic degradation of a pharmaceutical pollutant showed that the TiO₂ nanotubes can be used as a promising material for application in wastewater treatment.

We have studied the inhibitory effect of some Monoterpenic Thiosemicarbazones on steel corrosion in 1 M HCl solution. The potentiodynamic polarization and electrochemical impedance spectroscopy were used. The Monoterpenic Thiosemicarbazones have inhibited significantly the dissolution of steel. The inhibition efficiency increased with increasing inhibitor concentration and also with the increase in temperature (293–323 K). Furthermore, the results obtained revealed that the adsorption of inhibitor on steel surface obeys Langmuir adsorption model and the thermodynamic parameters such as enthalpy and activation energy were determined. The scanning electron microscopy combined with dispersive X-ray spectroscopy examinations were used to see the shape of the surface morphology and to determine the elemental composition. Scanning electron microscope (SEM) images show that the surface damage decreases when the inhibitor is added. The quantum chemical calculations using density functional theory (DFT) were performed in order to provide some insights into the electronic density distribution as well as the nature of inhibitor-steel interaction.

The inhibition efficiency of Atlas cedar essential oil (ACEO) as a green corrosion inhibitor on steel in 1 m hydrochloric acidic was studied. The effects of temperature and the concentration of the ACEO inhibitor on the inhibition efficiency were studied. Potentiodynamic polarization and electrochemical impedance spectroscopy were used to test the performance of the inhibitor. We found that the inhibition efficiency of ACEO exceeded 88% at 1 g/l at 298 K and increased with increasing concentration. The evaluation of activation and thermodynamic parameters reveals that the organic molecules of cedar essential oil and its fractions act by chemical adsorption on the metal surface. The adsorption of the inhibitor on the surface of steel is in a good agreement with the Langmuir adsorption isotherm. Increasing concentration of the corrosion inhibitor enhances the surface coverage and formation of a protective film.