Theoretical and Experimental Studies for Inhibition Potentials of Imidazolidine 4-One and Oxazolidine 5-One Derivatives for the Corrosion of Carbon Steel in Sea Water

Rehab M Kubba,Nada M Al-Joborry,Naeemah J Al-Lami

doi:10.24996/ijs.2020.61.11.3

Abstract

Two derivatives of Iimidazolidin 4-one (IMID4) and Oxazolidin 5-one (OXAZ5), were investigated as corrosion inhibitors of corrosion carbon steel in sea water by employing the theoretical and experimental methods. The results revealed that they inhibit the corrosion process and their %IE followed the order: IMID4 (89.093%) > OXAZ5 (80.179%). The %IE obtained via theoretical and experimental methods were in a good agreement with each other. The thermodynamic parameters obtained by potentiometric polarization measurements have supported a physical adsorption mechanism which followed Langmuir adsorption isotherm. Quantum mechanical method of Density Functional Theory (DFT) of B3LYP with a level of 6-311++G (2d, 2p) were used to calculate the geometrical structure, physical properties and inhibition efficiency parameters, in vacuum and two solvents (DMSO and H2O), all calculated at the equilibrium geometry, and correlated with the experimental %IE. The local reactivity has been studied through Mulliken charges population analysis. The morphology of the surface changes of carbon steel were studied using SEM and AFM techniques.

Highlights

Corrosion of metals is a serious material deterioration problem from both structural and economic integrity standpoint, but it can be largely controlled by the suitable strategies
The nucleophilic and electrophilic electronic charge values of the two inhibitors are found to be greater in the solutions of dimethyl sulfoxide (DMSO) and H2O than in vacuum, this is shown in Tables- (5, and 6) for IMID4 and OXAZ5, respectively
The inhibition efficiency was measured for inhibitors using potentiodynamic polarization measurements indicated that the studied inhibitors are classified as mixed inhibitors in saline water, because the addition of the two inhibitors is found to affect both the anodic and cathodic process

Summary

Introduction

Corrosion of metals is a serious material deterioration problem from both structural and economic integrity standpoint, but it can be largely controlled by the suitable strategies. In density function theory (DFT) the researcher has to test huge number of organic compounds to select a potential corrosion inhibitor. This type of search costs money, effort and time. The inhibition of (IMID4) and (OXAZ5) were studied experimentally in saline solution of 3.5% NaCl using potentiostatic polarization meaurements, and theoretically, using DFT method of (6-311/ B3LYP++G (2d, 2p)) level using Gaussian 09 program. These calculations were done for obtaining the parameters of the corrosion efficiency in three media (vacuum, DMSO, and water).

Description dihedral angle

Global molecular reactivity

Adsorption isotherm

Findings

Conclusions