Carbon steel corrosion inhibition in acidic medium by expired drugs

Corrosion and expired pharmaceutical materials represent a research spot because of their important issues in earth planet and human life. Three different expired drugs were bought from pharmacies in Baghdad city, Iraq and tested to determine their efficiencies in solving carbon steel corrosion in 1M HCl solution. Various exposure times were subjected to test Citicoline (Samozina, syrup, 100 mg in 1mL); Carbocisteine (5%) (Rhinathiol syrup, 750 mg); or Paracetamol (Panalife syrup 120 mg in 5mL) as an inhibitor protect carbon steel specimen from being corroded. Inhibition efficiencies (IE%) of the tested drugs were ranged from low to high values reflecting the effects of drug- active component type, time, concentration, and acidic hydrolysis as a suggested explanation. Temkin isothermal model was applied and Kads were ranged from [(26.43374-183.549), (10.36883 - 311.2802), and (3.499144 - 61.50259)] for Citicoline, Carbocisteine, and Paracetamol respectively. While Δ Gads values (in negative sign) were varied from (18.0494-22.8559, 15.7418-24.1738, and 13.033-20.1562) for Citicoline, Carbocisteine, and Paracetamol respectively. From Δ Gads values, it can be concluded that physisorpion than chemisorption was occurred.