EXPIRED AMOXICILLIN AND PENICILLIN V POTASSIUM TABLETS AS THE GREEN CORROSION INHIBITOR FOR LOWCARBON STEEL IN ACETIC ACID SOLUTION CONTAINING CHLORIDE IONS

The recycle and utilization of expired drugs is a challenge for many countries at present. The employment of expired drugs as green corrosion inhibitors is expected to address both drug recycling and corrosion prevention issues, with significant economic and environmental value. Herein, the individually and combination corrosion inhibition performance of expired amoxicillin (AMC) and penicillin V potassium tablets (PVP) for lowcarbon steel in 20% acetic acid solution containing 600 mg L^-1 chloride ion are evaluated by electrochemistry and weight loss method. Both the AMC and PVP present the mixed-type corrosion inhibitors mainly affect the cathode process when used individually. The optimum inhibition efficiency is 61.22% (AMC) and 79.21% (PVP), which all appear in 5.0 × 10^-3 mol L^-1. The AMC and PVP are adsorbed on the steel surface by mixed physisorption and chemisorption, which are consistent with the Langmuir adsorption isotherm. The corrosion inhibition rate drops sharply when AMC and PVP are combined use with a close mole ratio. But a small amount of PVP significantly enhance the corrosion inhibition effect of AMC, the corrosion inhibition rate from 61.22 to 79.72%. The corrosion inhibition rate of AMC and PVP combination inhibitor decreased with the increase of temperature.

Keywords:
expired drugs; corrosion inhibitor; combination; acetic acid; lowcarbon steel.