By: Mimi Martinez
Carbon steel is widely utilized in construction due to its affordability, accessibility, and strength. However, it is susceptible to rapid chemical and electrochemical corrosion, especially in acidic environments. Corrosion inhibitors play a crucial role in mitigating the degradation of materials like carbon steel exposed to corrosive solutions such as acids.
A recent study[i] investigated the potential of an expired pharmaceutical, Thiocolchicoside (ETC), to prevent corrosion of carbon steel (1040CS) in highly acidic conditions (1 M HCl). Expired pharmaceuticals are typically disposed of via incineration rather than recycling. Interestingly, these drugs have been found to exhibit corrosion inhibition properties when applied to metals exposed to corrosive solutions. This dual benefit addresses both waste reduction and corrosion control in industrial applications.
The study employed weight loss analysis, electrochemical impedance spectroscopy (EIS), and potentiodynamic polarization (PP) tests to evaluate the corrosion inhibition efficiency of ETC. Results indicated that increasing the concentration of ETC led to higher inhibition efficiencies, achieving up to 93.3%, 90.7%, and 91.4% according to EIS, PP, and weight loss measurements, respectively.
However, the effectiveness of ETC decreased at elevated temperatures, with inhibition efficiencies dropping from 91.83% at 298 K to 78.63% at 318 K (both at 400 ppm concentration). Surface studies using scanning electron microscopy (SEM), atomic force microscopy (AFM), and Fourier transform infrared spectroscopy (FTIR) confirmed that ETC molecules adsorbed strongly onto the surface of 1040CS, forming a protective layer.
This study underscores the potential of repurposing expired pharmaceuticals like Thiocolchicoside as effective corrosion inhibitors, offering a sustainable solution to both environmental and industrial challenges.
[i] https://www.nature.com/articles/s41598-025-07609-y
