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

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 degrees 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.