Recycling of Expired Lactulose Drugs as Eco-Friendly Corrosion Inhibitor for Steel Alloys in Acidic Environment: Gravimetrical and Electrochemical Studies

Lactulose is a synthetic sugar that is used to treat constipation and liver disease. The sweet taste of this medicine makes it appealing to children, putting their lives in danger. The consumption of unused or expired medicines is increasing the number of child deaths. The current article proposes using expired water-soluble lactulose as a corrosion inhibitor for the carbon steel electrode in a 1.0 M HCl acidic environment. The effectiveness of the expired Lactulose drug's ability to inhibit was assessed using electrochemical and gravimetric methods. Investigated were the effects of expired drug concentration, reaction temperature, and pH. Corrosion inhibition rose as concentration grew, fell as the temperature rose, and rose yet further when pH fell. Gravimetric methods include direct mass loss and atomic absorption spectroscopy (AAS). The expired medications impede both the anodic and the cathodic potential, according to data from potentiodynamic polarization (PDP), proving that they are mixed-type inhibitors. An electrochemical impedance spectroscopy (EIS) analysis revealed that the expired medication enhances polarization resistance by adhering to the metal/electrolyte contact. This kind of adsorption was modeled using the Langmuir adsorption isotherm. The viability of employing expired Lactulose medicines as potential harmless green corrosion inhibitors for steel in an industrial setting at lower pH is indicated by the good agreement between the applied methodologies (±2 %).