The inhibition of carbon-steel corrosion in seawater by streptomycin and tetracycline antibiotics: An experimental and theoretical study

The corrosion inhibition of Tetracycline and Streptomycin on the carbon-steel, Fe (110), in seawater was evaluated using weight loss, Tafel polarization, electrochemical impedance spectroscopy and SEM morphometric methods. The surface adsorption of inhibitors follows the Langmuir adsorption isotherm and acts as spontaneous mixed type corrosion inhibitors on the carbon-steel surface. The related thermodynamic parameters (E-a, K-ads, Delta G(ads), ads, ads, Delta H-not equal and Delta S-not equal) were evaluated and the interaction energy for Streptomycin was more than the Tetracycline. The SEM morphometric showed a good protection effect of inhibitors on carbon-steel in the presence of seawater and this was more efficient for Streptomycin. To emphasize the further insight into the efficiency of inhibitors, the Quantum chemical analysis and molecular dynamics simulations were used to find the most stable configuration and adsorption energies for inhibitors on the carbon-steel surface. The theoretical quantum chemical data such as E-HOMO, eta, chi, molecular surface area, MV, mu, alpha and Delta N were in agreement with inhibition efficiencies (IE %) that were obtained experimentally. AlsO, the molecular dynamics simulation showed the most stable configuration and adsorption energies of Streptomycin and Tetracycline on the carbon-steel and this follows the order of Streptomycin > Tetracycline, as verified by the experimental data. (C) 2016 Published by Elsevier B.V.