Ahmed H. Tantawy

Synthesis and evaluation of novel series of Schiff base cationic surfactants as corrosion inhibitors for carbon steel in acidic/chloride media: experimental and theoretical investigations

A new family of Schiff base cationic surfactants (CSSB) having various alkyl chain lengths were prepared and their chemical structure was elucidated by using different spectroscopic techniques (FTIR, 13C-NMR and 1H-NMR). The surface activity parameters of the prepared surfactants were measured to set the adsorption and micellization characteristics at the water/air interface. The corrosion inhibition capability of these surfactants was investigated on a carbon steel surface in 3.5% NaCl+ 0.5 M HCl solutions at different temperatures (30–60 °C) by potentiodynamic polarization and electrochemical impedance spectroscopy measurements. The results revealed that CSSB compounds inhibited corrosion of carbon steel in the investigated acidic chloride containing environment. It was found that the inhibition efficiency increases with an increase in inhibitor concentrations and decreases with increasing temperature. Polarization data indicated that the investigated compounds act as mixed-type inhibitors, and the adsorption isotherm basically obeys the Langmuir isotherm. The corrosion inhibition mechanism was discussed based on the potential of zero charge value. An SEM/EDX studies confirmed that CSSB inhibitors could form films by adsorption on the carbon steel surface. The theoretical predictions exhibit good agreement with empirical results.

Empirical and Theoretical Calculations for Corrosion Inhibition of Carbon Steel C1018 in Acidic Solutions Using Some Selected Fatty Acid Surfactants

Abstract Three different surfactants based on fatty acids (octanoic, tridecanoic and oleic) and ethylenediamine were synthesized and their chemical structures were confirmed by FT-IR, 1H-NMR and 13C-NMR spectroscopy. The surface-active properties of the prepared surfactants were determined by using interfacial tension.The synthesized surfactants were evaluated as corrosion inhibitors for carbon steel in a solution of 0.50 M HCl at 40 ℃. Potentiodynamic polarization, linear polarization resistance corrosion rate and electrochemical impedance spectroscopy measurements were used for this study. Experimental results showed that, the inhibition efficiency increases with increasing the surfactant concentration, getting maximum inhibition efficiency ranged between 97.10 and 99.61% at 400 ppm. Potentiodynamic polarization curves showed that, the three compounds act as mixed type. The adsorption of investigated surfactants obeyed the Langmuir adsorption isotherm, and the thermodynamic parameters were calculated and discussed. Obvious correlation was found between the corrosion inhibition efficiency and the quantum chemical parameters. The obtained theoretical results have been adapted with the experimental data.