Inventor: Prof. Dr. Rihab Majid Mohammed Rasheed Kuba/Department of Chemistry, College of Science, University of Baghdad
Abstract
The patent involve, protection Carbon Steel from corrosion in saline water by new derivative N-benzyl-5-bromo-3-[(imine aceto urea)]-2-oxo indole (5BIO).The protection of Carbon steel achieved by using inhibition method, where new derivative was synthesis and used as corrosion inhibition, and the corrosion testing achieved by extrapolation of polarization curves which obtained from potentiostatic measurement at different concentrations and temperatures 288, 303, 313, and 328 K. The results showed that the inhibition efficiency increased with increasing inhibitor concentration and decrease with increasing temperature. Polarization curves showed that the evaluated compounds affected as mixed inhibitors affect both the anodic and cathode processes. The adsorption on carbon steel surface obeys the Langmuir adsorption isotherm. Kinetic and thermodynamic parameters governing the corrosion and adsorption process were studied and discussed. The negative values of the Gibbs free energy of adsorption ΔG0ads (-65.558, -67.245, -69.570, -70.508 kJ.mol-1) for 5BIO inhibitor indicate that the adsorption on carbon steel surface is a spontaneous process.
The adsorption of the investigated compound is found to follow Langmuir’s adsorption isotherm which indicating that the inhibition process occurs via adsorption. The values of Kads were (5.520, 1.510, 1.040, 0.190 L mol-1) for 5BIO inhibitor indicated that the concentration of inhibitor on metal surface and the less negative value of ∆Hads (-26.738 kJ.mol-1) than (-40 kJ.mol-1) for 5BIO, reveal to physisorption process. The lower ∆Sads (0.867 kJ mol-1 K-1), reveal to less random interaction and more stable adsorbent inhibitor. The SEM image of carbon steel surface with 3.5%NaCl in absence of inhibitor reveals that it consists of spherical particles formed by aggregation. The scale bar for this image is 300 μm and the energy of the acceleration beam employed was 20kV.
The SEM image of CS surface with 3.5% NaCl in the presence inhibitor indicated that the composite phase between the CS surface and the inhibitor was established, and the inhibitor dispersed on the surface of the CS base. Considering the inhomogeneous way of metallic surfaces coming, about because of the presence of cross section deformities and disengagements, an eroding metal surface is for the most part described by different adsorption locales having unequivocal activation energies and warmth of adsorption. Inhibitor atoms may in this case be adsorbed all the more promptly at surface destinations having appropriate adsorption enthalpies, so the SEM image reveals the agglomeration of the inhibitor in some places.