DIYALA JOURNAL OF ENGINEERING SCIENCES

Abstract

The application of empirical and quantum chemical models on the corrosion inhibition of steel in hydrochloric acid in presence of phenylthiourea (PTU) as corrosion inhibitor have been modeled. Two mathematical models were used, third order polynomial model and Arrhenius type equation model. Levenberg-Marquardt method was used to evaluate the coefficients of two Models. Two models were suitable to represent the corrosion rate data at different conditions. The correlation coefficient of third order model was 0.973, while for the Arrhenius type model was 0.919. The structure of inhibitor was optimized by ArgusLab 4.0.1 package. The quantum chemical parameters (EHOMO, ELUMO, ΔE, and dipole moment µ) were estimated by PM3-SCF method.