Novel Anionic 4-Tert-Octyl Phenol Ethoxylate Phosphate Surfactant as Corrosion Inhibitor for C-steel in Acidic Media

Novel anionic 4-tert-Octylphenol Ethoxylated Phosphate Dipotassium salt (ethoxylated with 5 moles of ethylene oxide) surfactant was prepared and designated as OP-5-EO-K2PO, was characterized for its structure using spectroscopic measurements, in addition, its surface properties were investigated. The results indicated that OP-5-EO-K2PO exhibits excellent surface activity. Evaluation of the prepared surfactant as a corrosion inhibitor was carried out. The inhibition effect of OP-5-EO-K2PO surfactant, on the corrosion of C-steel in 0.5 M HCl was studied by potentiodynamic polarization, electrochemical impedance spectroscopy (EIS) and electrochemical frequency modulation (EFM) techniques. It was found that the novel anionic surfactant acts as effective inhibitor and its inhibition efficiency was significantly increased with increasing concentration. Polarization curves revealed that the novel prepared anionic surfactant represents mixed-type inhibitors. Adsorption of the investigated surfactant led to a reduction in the double layer capacitance and an increase in the charge transfer resistance.