Corrosion inhibition of mild steel by using Carbimazole/Zn+2 system in NaCl medium

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Sebha University
Corrosion is defined as the degradation of metallic materials under the effect of the environment. This is a surface reaction that propagates in progressive ways affecting the integrity of the material. Under the aggressive environment, corrosion leads to the formation of corrosion products, and to a progressive generalized or localized loss of matter. The use of inhibitor material is considered as a one way to protect the metal surface against corrosion. The inhibitor is chemically adsorbed on the surface of the metal and forms a protective thin film with inhibitor effect or by combination between inhibitor ions and metallic surface. Or, the inhibitor leads a formation of a film by oxide protection of the base metal. The current work was evaluated the corrosion inhabitation of carbon steel in NaCl solution by carbimazole\Zn system. the ability of carbimazole as a good corrosion inhibitor is enhanced slightly in presence of Zn+2 when the concentration of carbimazole increased and this may be attributed to the protective film formed on the metal surface was withstand the continuous attack of corrosive ions. Also, the formation of complex Fe-carbimazole/Zn+2 linkages on the anodic sites of the metal surface during the immersion time may play a role in the improvement in adsorption of inhibiter system via coverage more area of the metal surface which reduced the exposure of anode sites to the corrosive media. By using Langmuir isotherm model to identify the inhibitor mechanism performance, the values of linear correlation coefficient were found close to unity (1) suggested that the adsorption of the studied inhibitors follows Langmuir isotherm model. Generally, values of ∆𝐺°ads up to -9.7 KJ/mol are attributed to the electrostatic interaction between the inhibitor molecules and the metal surface (physical adsorption), whilst those at -10.6 KJ/mol or a little more negative are consistent with chemical bonding of the inhibitor to the sample (Chemisorptions).