Copper Corrosion Inhibition by Cefpodoxime Drug in 1M Nitric Acid : Experimental and DFT approaches

The copper corrosion inhibition in one molar nitric acid by cefpodoxime drug is studied via mass loss technique at 303-323K and quantum chemistry. The results show that the studied drug is an efficient inhibitor which adsorbs spontaneously on copper through Langmuir model. Thermodynamic adsorption functions and activation ones were determined and analyzed. They indicate a predominant physisorption process and an endothermic dissolution process. Scanning electron microscopy was used to characterize the metal surface. Quantum chemical calculations at B3LYP level with 6-31G (d, p) basis set lead to molecular descriptors such as EHOMO (energy of the highest occupied molecular orbital), ELUMO (energy of the lowest unoccupied molecular orbital), ΔE (energy gap) and μ (dipole moment). The global reactivity descriptors such as χ (electronegativity), ƞ (hardness), S (softness) and ω (electrophilicity index) were derived using Koopman’s theorem and analyzed. The local reactivity parameters including Fukui functions f(r ) and local softness s(r ) were determined and discussed. Theoretical results were found to be consistent with the experimental data.