Aluminum corrosion inhibition by cefixime drug: Experimental and DFT studies

Corrosion inhibition of aluminum in 1 M HCl by cefixime drug has been studied at 298-318 K using mass loss, Tafel polarization (at 298 K) and quantum chemical methods based on density functional theory (DFT) calculations. The results showed that inhibition efficiency increases up to 90.41 % with increase of the inhibitor concentration from 0.02 to 2 mM, but decreases with a rise of the solution temperature. Adsorption of cefixime molecules on the corroding aluminum surface obeys Langmuir adsorption isotherm and occurs spontaneously mostly through a physisorption process. The activation energy (Ea) as well as other thermodynamic parameters of the inhibition process are calculated and discussed. Potentiodynamic polarization data revealed that cefixime acts as mixed-type inhibitor and pointed out an agreement with mass loss results. Surface analysis is performed using scanning electron microscopy (SEM) which confirmed existence of a protective film of inhibitor molecules on the aluminum surface. In addition, global and local reactivity parameters of the studied molecule are analyzed and discussed. The computed results are found in agreement with experimental data.