Effect of expired paracetamol–Zn+2 system and its synergistic effect towards iron dissolution inhibition and green inhibition performance

Abstract

Chemical and electrochemical techniques were used to evaluate the effect of expired paracetamil–Zn+2 systems (PC–Zn+2) as potential nontoxic inhibitor for the dissolution process of iron in 2.0 M sodium chloride corrosive solution. The chemical techniques used in this work are gravimetric, thermometric and atomic absorption spectroscopy (AAS), whereas the electrochemical techniques are open circuit potential, potentiodynamic polarization and electrochemical impedance spectroscopy. The dissolution inhibition efficiencies of the used system (PC–Zn+2) were increased with increasing mixed inhibitor concentrations and rising temperature, with significant synergistic effect between expired paracetamol drugs and zinc acetate, the values of polarization resistance (R p) was increased and the capacitance of the interface (C dl) was decreased in the presence of mixed inhibitor system (PC–Zn+2) more than in case of individual inhibitors. Potentiodynamic polarization curves indicate that the used system act as a mixed inhibitor for the dissolution of iron. The inhibition of corrosion is due to adsorption of (PC–Zn+2) on the metal surface and formation of barrier film that separates the metal from the corrosive medium and the inhibitor adsorption was obeying Langmuir adsorption isotherm. The corrosion inhibition is due to adsorption, adhesion of the inhibitor molecules, and formation of a protective layer on the steel surface. The data obtained from different techniques are in good agreement with each other to indicate the possibility of using expired paracetamol drugs—Zn+2 mixed system as eco-friendly corrosion inhibitor for iron in concentrated corrosive sodium chloride solution.