Repurposing expired fosfomycin trometamol as a sustainable corrosion inhibitor: An electrochemical evaluation for mild steel protection in 1 M HCl

Abstract

This study, which was conducted as a different application area of Monurol®, known as an expired and widely prescribed urinary tract infection antibiotic, evaluated the corrosion inhibition performance of its active compound Fosfomycin Trometamol for mild steel in acidic environment. The investigation focused on four different concentrations: 1.0×10⁻3 M, 1.0×10⁻4 M, 1.0×10⁻5 M, and 1.0×10⁻6, each formulated in a molar concentration of hydrochloric acid solution. Electrochemical impedance spectroscopy (EIS) and polarization analyses were conducted after one hour of immersion to evaluate the effect of the inhibitor. The results demonstrated a consistent enhancement in corrosion protection efficiency with increasing inhibitor concentration. At 1.0×10⁻3 M, the highest inhibition efficiency of 91.8% was achieved based on EIS data, accompanied by a significant increase in charge transfer resistance from 72 Ω cm² (blank) to 878 Ω cm². Polarization results revealed a notable decrease in corrosion current density from 265 µA cm⁻² (blank) to 22 µA cm⁻² in the presence of the highest inhibitor dose. Furthermore, FE-SEM images of the mild steel surfaces confirmed that specimens exposed to Fosfomycin Trometamol exhibited smoother and less corroded morphologies compared to the uninhibited sample. These findings suggest that expired or repurposed Fosfomycin Trometamol can serve as a potential green inhibitor in acid-induced corrosion environments.

Keywords

• Fosfomycin Trometamol
• Mild steel
• Green inhibitor
• Adsorption
• Acid corrosion

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