Experimental Evaluation of Unpreprocessed-Expired Paracetamol Drugs as Corrosion Inhibitor for Mild Steel in Hydrochloric Acid

Abstract

The widespread corrosion of critical oil and gas infrastructure requires development of innovative and environmentally sustainable solutions. This research considers the repurposing of hitherto un-useful expired drugs to meet this challenge and to do so in ways that also puts stop to the menacing and illegal circulation of expired pharmaceuticals in developing economies. The corrosion inhibitory potential of expired paracetamol was evaluated for mild steel in acidic environment. Electrochemical analysis revealed that the corrosion current decreased from for the mild steel immersed in the blank/uninhibited 0.5M HCl environment to in the case of the sample in the 8g/l environment. The concentration of dissolved ions of iron in the acidic environment also followed this trend supported by the results obtained from the gravimetric analysis. Optical microscopy showed gradual covering of the corroding surface by a layer of inhibitor film with increasing concentration of the additive in the acidic environment. The corrosion inhibition efficiency increased with increasing concentration of the expired drug, reaching a maximum of 73.24% for 8.0 mM of expired paracetamol directly dissolved in the acid. Expired paracetamol acted as a mixed-type inhibitor for mild steel in 0.5M HCl and the corrosion inhibition process was spontaneous. All analyses agreed that expired paracetamol drug is capable of inhibiting corrosion of mild steel in HCl and that the corrosion inhibition is achievable without prior pretreatment. The research is fundamental as it attempts to lay some groundwork for further research towards developing viable and marketable product from this category of materials.