Experimental and computational studies of two antibacterial drugs as corrosion inhibitors for mild steel in acid media

The inhibition of mild steel corrosion in 3% HCl solution by sulfamethoxazole (SZ) and norfloxacin (NF) were investigated at 25 °C using weight loss measurement. The measurements reveal that the inhibition efficiency grows with increasing concentrations of inhibitors, and the inhibition efficiency decreases in the order NF > SZ. The adsorption of inhibitor molecule on mild steel surface follow Langmuir isotherm. Quantum chemical calculation was performed to correlate electronic structure parameters of SZ and NF with their inhibition performances. The molecular dynamics simulations were applied to find the equilibrium adsorption configurations and calculate the interaction energy between inhibitors and iron surface. The efficiency order of the studied inhibitors obtained by experimental results was verified by theoretical calculations.