Research Article
S Ouattara, PM Niamien, EB Avo
Abstract
Ciprofloxacin hydrochloride has been tested as an inhibitor of copper corrosion in 1.0 M nitric acid, using mass loss technique and DFT (Density Functional Theory) calculations. The experimental studies have been performed in the concentration range of 0.05 mM to 1 mM and the temperature range of 308 K to 328 K. The results show that the inhibition efficiency of the studied molecule is concentration and temperature dependent. The fractions of surface coverage and the related concentrations were used to fit adsorption isotherms including, Langmuir, El-Awady, Temkin, Freundlich and Flory Huggins. Though the Langmuir isotherm was found to be the best isotherm, it could not be applied strictly because of deviation from the assumptions used to derive this isotherm. So, the appropriate isotherm was the modified Langmuir isotherm. To solve the ambiguity usually associated with the characterization of the adsorption processes of organic compounds, the Dubinin-Radushkevitch isotherm and that of Adejo-Ekwenchi were used. Furthermore, DFT calculations based on B3LYP functional and 6-31G (d) basis set were used to derive the molecular properties of ciprofloxacin. The relationships between the inhibition efficiency and some molecular descriptors have been discussed. The Fukui functions were calculated and used to locate the sites of electrophilic and nucleophilic attacks via the dual descriptor. Quantum chemical studies corroborate experimental results.