Adsorption Behavior and Corrosion Inhibition of EPP for Q235 Steel in H2SO4 Solution

The inhibition effect of N,N-diethylammonium O,O'-di(2-phenylethyl)dithiophosphate (EPP, [NH2(Et)2][S2P(OCH2CH2Ph)2]2) against the corrosion of Q235 steel in H2SO4solution was studied by weight loss measurement, potentiodynamic polarization and SEM(scanning electron microscope) techniques. The results show that EPP acts as an excellent corrosion inhibitor in 5% H2SO4by suppressing simultaneously the cathodic and anodic processes via chemical adsorption on Q235 steel surface, which complies with the Langmuir adsorption isotherm. Polarization curves indicate EPP is a mixed-type inhibitor. The effects of temperature, acid concentration and immersion time were also studied.