Investigation of the formation of self-assembled monolayer films of some analgesic and antibiotic drugs on the surface of copper and their inhibition effect on the corrosion of copper

Unused or expired pharmaceutical waste poses significant environmental risks and economic losses. This study presents a practical and potentially effective approach for pharmaceutical recycling. For the first time, drugs were utilized to fabricate self-assembled monolayers (SAMs) on copper (Cu) metal surfaces. Analgesics containing paracetamol (PC) and aspirin (AS) as active ingredients, along with the antibiotic co-amoxiclav (KA), were selected as model pharmaceuticals for SAM fabrication. The SAMs were prepared in ethanol solvent at 298 K for 24 hours using various drug concentrations. Additionally, each pharmaceutical was tested as a corrosion inhibitor at the same concentrations used for SAM preparation in identical corrosive environments. Both the SAM films and inhibitor films formed on copper surfaces in sodium chloride (NaCl) solution were characterized using energy-dispersive X-ray spectroscopy (EDX), scanning electron microscopy (SEM), atomic force microscopy (AFM), and contact angle measurements. The corrosion protection performance of the prepared SAM films and inhibitors was evaluated in 3.5% NaCl solution. Results demonstrated that both SAM and inhibitor film properties were strongly dependent on drug concentration, with all pharmaceuticals exhibiting high corrosion inhibition efficiencies in both SAM and inhibitor forms. The SAM films displayed homogeneous, compact structures with excellent adhesion to copper surfaces. This study represents the first reported strategy employing pharmaceutical compounds to create SAM films on metal surfaces, offering a dual-functional approach that combines advanced material protection with drug recycling. The findings provide new insights into environmentally friendly, cost-effective corrosion inhibitors that contribute to green chemistry and circular economy principles.