CORROSION INHIBITION OF CARBON STEEL BY SOME ANIONIC SURFACTANTS IN 0.5M H_2SO_4

摘要

The inhibitory effect of some anionic surfactants as 1 Dodecane sulfonate sodium (SSD) and Dioctyl sulfosuccinate sodium (AOT) at various combinations of these organic compounds (AOT/1-Dodecane sulphonate sodium: 20/80 ppm, 40/60 ppm, 50/50 ppm, 60/40 ppm, 80/20 ppm and 100 ppm) on the corrosion behavior of carbon steel in 0.5M H_2SO_4 medium at temperature of 25℃ was studied by potentiostatic and potentiodynamic polarization, electrochemical impedance spectroscopy (EIS), Fourier transform infrared spectroscopy (FT-IR) and metallurgical microscopy techniques. The effect of inhibitor concentration on the corrosion rate, surface coverage and inhibition efficiency was investigated. Results show that these organic inhibitors exert a great inhibiting effect on carbon steel corrosion and act as a mix-type inhibitor. The inhibition efficiency of organic inhibitors may be due to either the adsorption of inhibitor molecules building a protective film or the formation of an insoluble complex of the inhibitor adsorption obeys the Langmuir model. The negative value of thermodynamic parameter like Gibbs free energy of adsorption ∆G°_(ads) indicates the spontaneity of adsorption process. Moreover, characterization using FT-IR demonstrates the adsorption of inhibitors and the formation of corrosion products on the carbon steel surface. EIS and potentiodynamic results confirm its corrosion inhibition ability.