<div><p><em>Corrosion inhibition of aluminum (Al) 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 aluminium surface obeys Langmuir adsorption isotherm and occurs spontaneously mostly through a physisorption process. The activation energy (</em><em>) 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.</em></p></div>

Cefixime, a third-generation semi-synthetic cephalosporin antibiotic was used as a copper corrosion inhibitor in 1M HNO 3 solution. The study was conducted through the weight loss technique at 298 -318 K and theoretical studies based on quantum chemistry. The studied drug inhibited the corrosion of copper in 1M HNO 3 over the cefixime concentration range (0.02 -2 mM). The inhibition efficiency increased with an increase in the inhibitor concentration to reach 91.07% at 2 mM, but decreased with an increase in temperature. The thermodynamic functions related to the adsorption of cefixime on the copper surface and that of the metal dissolution were computed and analyzed. The results point out spontaneous adsorption, mainly through a physisorption mechanism following Langmuir adsorption isotherm model and an endothermic dissolution process. Quantum chemical calculations were also performed at B3LYP level with 6-31G (d, p) basis set and lead to molecular descriptors such as E HOMO (energy of the highest occupied molecular orbital), E LUMO (energy of the lowest unoccupied molecular orbital), ΔE (energy gap) and μ (dipole moment). The global reactivity descriptors such as χ (electronegativity), χ (global hardness), S (global softness), and ω (electrophilicity index) were derived using Koopman's theorem and analyzed. The local reactivity parameters, including Fukui functions and dual descriptors were determined and discussed. Experimental and theoretical results were found to be in good agreement.

Inhibitive properties of 7-(ethylthiobenzimidazolyl) theophylline (7-ETBT) molecule for the corrosion of alu-minum (Al) in one molar hydrochloric acid medium have been investigated using mass loss and Tafel polariza-tion methods. The results suggest spontaneous and predominant physical adsorption of 7-ETBT on the metal surface which obeys Langmuir isotherm model. The studied inhibitor showed excellent inhibition efficiency up to 94.07 % at 298 K for its optimum concentration (2 mM). Moreover, Tafel polarization method revealed that 7-ETBT is a cathodic-type inhibitor. Further investigation on the morphology using scanning electron microscopy (SEM) has confirmed the existence of a protective film of inhibitor molecules on aluminum surface. Theoreti-cal approach for the performance of 7-ETBT as Al corrosion inhibitor is also done using Density Functional Theory (DFT) level with B3LYP exchange correlation functional for 6-31G (d, p) basis set. The results provided by this theoretical study are consistent with the experimental data. All the results have shown an evidence of the effectiveness of the inhibitive effect of 7-ETBT on Al.

Corrosion inhibition of aluminum in 1 M HCl by cefixime drug has been studied at Tafel polarization (at 298 K)