Appraisal of expired linezolid and piperacillin as potent and harmless inhibitors for mitigation of copper corrosion in 1.0 M HNO ₃

The inhibitory potency of two antibiotics that have expired, namely, linezolid (LIN) and piperacillin (PIP) was investigated for inhibiting Cu corrosion in 1.0 M HNO3 solution. Chemical, electrochemical and theoretical analyses were employed to verify the efficacy of these drugs’ inhibition. The efficacy of inhibition rises with rising the amounts of LIN and PIP and with depression of temperature. The inhibition impact of these drugs results from the formation of a complex between copper ions and the drug and its adsorbing to the copper surface via the Langmuir absorption isotherm. Potentiodynamic polarization confirmed that these drugs operate as mixed inhibitors. The description and interpretation of the thermodynamic functions of the activation and adsorption processes are investigated. These expired drugs acted as pitting corrosion inhibitors, as seen by the transfer of pitting potentials to a higher positive value. All the outcomes illustrate that both LIN and PIP were beneficial inhibitors of Cu corrosion in 1.0 M HNO3 solution, and PIP is a more effective inhibitor than LIN at all doses examined. The theoretical evaluations of linezolid and piperacillin corrosion inhibition efficiency were performed by DFT theory using the B3LYP method with a 6-311++G(d,p) basis set. The quantum chemistry analyses revealed a relationship between the theoretically expected inhibitory effects of studied compounds and their molecular structures, implying that structural factors offered information into the potential inhibition mechanism.