Low toxic polymeric surfactant as a corrosion inhibitor for mild steel in hydrochloric acid medium

Abstract

Purpose Surfactants have been reported to have high inhibition efficiencies for corrosion of steel. This paper aims to study the performance of a low toxic copolymer of polydimethylsiloxane and polyoxyalkylene (POA) surfactant named as POPS, as a corrosion inhibitor for mild steel (ASTM 1005) in hydrochloric acid (HCl) solution at 25°C. Design/methodology/approach To evaluate POPS efficiency as a corrosion inhibitor, the following techniques were used: surface tension measurements, weight loss measurements, open circuit potential monitoring, potentiodynamic polarization curves, electrochemical impedance spectroscopy (EIS), scanning electron microscopy and contact angle measurements. Findings Results indicated that POPS acted as a mixed corrosion inhibitor and led to a hydrophobic protector film on the metal surface. The adsorption process obeyed the Langmuir adsorption isotherm by chemisorption. The maximum efficiency of the surfactant studied was achieved in a concentration around the critical micelle concentration. Originality/value Surfactant (POPS) of low level of toxicity acts as a mixed corrosion inhibitor in HCl medium. Inhibitor film formation was characterized by EIS results. A mechanism for corrosion inhibition is proposed.