Pyrazolone derivatives as corrosion inhibitors for C-steel in hydrochloric acid solution

• Published in: Desalination 2006-11, Vol.201 (1), p.1-13
• Main Authors: Fouda, A.S., Al-Sarawy, A.A., El-Katori, E.E.
• Format: Article
• Language: English
• Subjects: Adsorption; Applied sciences; C-steel; Chemical engineering; Corrosion inhibitors; Exact sciences and technology; HCl; Polarization; Pollution; Pyrazolone derivatives; Synergistic effect; Weight loss
• ISSN: 0011-9164; 1873-4464
• DOI: 10.1016/j.desal.2006.03.519

4-phenylazo-3-methyl-2-pyrazolon-5-one and three of its derivatives have been investigated as corrosion inhibitors for C-steel in 2 M hydrochloric acid solution using weight-loss and galvanostatic polarization techniques. The efficiency of the inhibitors increases with the increase in the inhibitor concentration but decreases with a rise in temperature. The conjoint effect of the pyrozolone derivatives and KBr, KSCN and KI has also been studied. The apparent activation energy ( E a *) and other thermodynamic parameters for the corrosion process have also been calculated. The galvanostatic polarization data indicated that the inhibitors were of mixed-type, but the cathode is more polarized than the anode. The slopes of the cathodic and anodic Tafel lines (β c and β a ) are approximately constant and independent of the inhibitor concentration. The adsorption of these compounds on C-steel surface has been found to obey the Frumkin's adsorption isotherm. The mechanism of inhibition was discussed in the light of the chemical structure of the undertaken inhibitors.