Evaluation of anti-corrosion performance of an expired semi synthetic antibiotic cefdinir for mild steel in 1 M HCl medium: An experimental and theoretical study

Abstract

In view of severity of metallic corrosion in different corrosive media, application of corrosion inhibitor has been very promising to overcome this problem. However, numbers of corrosion inhibitors investigated earlier are not environmentally safe as well as costlier. To overcome these problems, researches are going on to develop efficient, environment friendly as well as cost effective corrosion inhibitor. In view of these facts, corrosion inhibition property of an expired anti-biotic, cefdinir (CDR) was investigated. This study includes anti-corrosion performance of CDR molecule against corrosion of mild steel (MS) in HCl medium. The results are summarized on the basis of weight loss, electrochemical, morphological and theoretical studies. The weight loss study infers that the rate of corrosion regularly decreased by the increasing the amount of CDR in acid solution. The cefdinir thus adsorbed on the MS surface and mitigate the corrosion rate. The adsorption of CDR on MS surface obeys Langmuir isotherm. The activation energy regularly increased by the presence of CDR and hence indicated that energy barrier for corrosion process to take place increased. The increased entropy of activation in presence of CDR assigned to entropy of solvent molecule. Potentiodynamic study infers that the CDR acts as mixed type of inhibitor. The value of Gibb's free energy suggested the electrostatic as well as chemical interaction of CDR molecule with mild steel surface. The theoretical study (Density functional theory, Fukui indices and Molecular dynamics) justifies the experimental results appreciably.