Petroleum quaternary ammonium surfactants mixture synthesized from light naphtha as corrosion inhibitors for carbon steel in 1 m HCl

A quaternary ammonium cationic surfactants mixture was synthesized from light naphtha, petroleum fraction. The mixture was analyzed by Fourier transform infrared spectroscopy and UV/Visible spectroscopy and was evaluated as a corrosion inhibitor for carbon steel in 1 m HCl, by gravimetry, potentiodynamic polarization and electrochemical impedance spectroscopy. The results showed that inhibiting efficiency increased with inhibitor concentration and temperature, and was independent of pH (in the range of 0-4) and immersion time; its optimal value was up to 84% for 560 mg/l at 25 degrees C. Experimental data showed that the cationic surfactants mixture acts as a mixed (anodic and cathodic) inhibitor and conformed to the Langmuir adsorption isotherm. Scanning electron microscopy images revealed the inhibiting capacity of the mixture against carbon steel acid corrosion.