Inibição à corrosão de aço-carbono em meio salino pelo heterociclo isatina veiculado em microemulsões

SALINE MEDIUM.Polar microemulsion systems (SME) based on saponified coconut oil (OCS) as surfactant were prepared in order to increase the solubility of the heterocycle isatin (IST) aiming at its application as corrosion inhibitor against AISI 1020 mild steel, in saline medium.The adsorptions phenomena of the tested SME systems (SME-OCS1-IST and SME-OCS2-IST) in the liquid/gas interface were evaluated by surface tension measurements which do not show significant differences in the presence of ion Cl -.The free energy values of the micellization proved the occurrence of spontaneous process.The corrosion inhibition effectiveness of SME-OCS2, SME-OCS1-IST and SME-OCS2-IST samples was evaluated in 0.5% aqueous NaCl using voltammetry linear scan method (LPR).The maximum efficiency findings were 73.2% for SME-OCS2, 88.2% for SME-OCS2-IST and 97.6% for SME-OCS1-IST.The spontaneity of the adsorption phenomena was also observed in the liquid/metal interface by analyzes of the adsorption free energy.In addition, since computational calculations have been found as a very relevant tool in the corrosion field, a theoretical study was performed in attempt to give support to the observed experimental results, in which B3LYP and 6-311++G(d,p) were applied aiming at investigation of geometry, electronic density aspects, HOMO-LUMO energy gap, as well as the binding between isatin and metal surface.