Experimental and computational investigation of an expired oxpentifylline as a corrosion shielding agent for mild steel in a simulated marine environment

The work presented highlights the corrosion mitigation function of expired Oxpentifylline and its role in mitigating mild steel from corrosion in an artificial sea environment. Expired Oxpentifylline inhibition performance on mild steel protection was examined through practical (weight loss, polarization, and impedance analysis), morphological (FTIR, SEM, EDAX, AFM, and Contact angle), and computational methods. According to the data, expired Oxpentifylline drug exhibits significant anti-corrosion properties at room temperature, showing the highest efficiency of 92% at 300 ppm. The temperature investigations show that the inhibitors' interaction is often described by the adsorption isotherm, as the inhibitor complies with the Langmuir isotherm. Studies on polarisation suggest that this green corrosion inhibitor has a mixed mode of action. The standard enthalpy of adsorption (ΔH° ads ) was determined to be −17 kJ/mol, indicating that oxpentifylline is physically adsorbed onto the steel surface. Furthermore, the greater value of activation energy (E a * = 19.09 kJ mol −1 ) observed for steel in the presence of 300 ppm of oxpentifylline, compared to the blank solution, further supports the predominance of physisorption mechanism. These findings have also been linked to computational studies (DFT, MC simulation, and sorption loading). The experimental findings were consistent with the theoretical parameters. A complete agreement was reached regarding the anticorrosion efficiencies calculated using the different methodologies. All the above results lay the groundwork for creating green inhibitors for mild steel.