Evaluation of (2-Hydroxyethyl) Triphenyl Phosphonium Bromide as Corrosion Inhibitor for Mild Steel in Sulphuric Acid

摘要

The inhibition effect of the (2-Hydroxyethyl) triphenyl phosphonium bromide (HETPB) on mild steelcorrosion in 0.5 M H2SO4 have been determined by electrochemical techniques like potentiodynamicpolarization (PDP), potentiostatic polarization (PSP) and electrochemical impedance spectroscopystudies (EIS). Potentiodynamic polarization study reveal that HETPB is an anodic type inhibitor with-2 -3 98% efficiency at the concentration range of (110 to 410 ) M for mild steel in 0.5 M sulfuric acid.Potentiostatic polarization study shows that HETPB is a non-passivating type of inhibitor at higherconcentrations and act as passivating type of inhibitor at lower concentrations. The corrosion behaviorof steel in 0.5 M H2SO4 without and with the inhibitor at various concentrations was studied at thetemperature range of (298 to 328) K. The adsorption of HETPB accords to Langmuir adsorptionisotherm. Kinetic parameter such as effective activation energy (Ea) has been evaluated from the effectof temperature on corrosion and inhibition processes. The negative values of thermodynamico parameter like Gibbs free energy of adsorption ( ads) indicate the spontaneity of adsorption process.The surface morphology of the tested mild steel specimens in the presence and absence of inhibitorshave been studied by using the respective images of SEM and AFM. Quantum chemical calculationshave been performed and several quantum chemical indices were calculated and correlated with thecorresponding inhibition efficiencies.