Electrochemical Studies of Expired Drug (Formoterol) as Oilfield Corrosion Inhibitor for Mild Steel in H2SO4 Media

The expired drug Formoterol (EDF) [N-(2-hydroxy-5-(1-hydroxy-2-((1-(4-methoxyphenyl)propan-2-yl)amino)ethyl)phenyl)formamide] was examined as potential corrosion inhibitor of mild steel in 1 M sulphuric acid (H2SO4) media using weight loss, electrochemical and surface studies. Formoterol has its medicinal importance in traditional medicine as beta 2 receptor. It is known for its long lasting duration and can be effective till 12 hours. So, this expired drug is chosen as environment friendly corrosion inhibitor for mild steel in sulphuric acid, as it is easily available, cheap and easy to use. The weight loss results discovered that samples covered with Formoterol showed less weight loss compared to the samples without Formoterol. The electrochemical tests including electrochemical impedance spectroscopy (EIS), and potentiodynamic polarization (PDP) demonstrated good mitigation efficiency of Formoterol in 1 M H2SO4 media. The mixed shift of the anodic and cathodic slopes advised that the Formoterol represented as mixed category. The surface studies were completed using scanning electron microscopy (SEM) and contact angle. Both the studies displayed even surface in existence of Formoterol and rough surface in its absence. The kinetic and thermodynamic results including activation energy, enthalpy, and entropy were also obtained. Quantum simulations were done using Gaussian 9.0 software using density functional theory (DFT) to get computational parameters that can support the experimental findings. All the experimental results are in decent pact respectively.