Application of expired Tramadol medicinal drug for corrosion inhibition of steel in acidic environment: Analytical, kinetic, and thermodynamic studies

• S.R. Al-Mhyawi

Department of Chemistry, Faculty of Science, University of Jeddah, Jeddah 22233, Saudi Arabia

Abstract: Tramadol is a well-known pain reliever that is classified as a synthetic opioid; leaving it in the environment after it has expired is extremely dangerous because it is harmful to children. As a result, the current research suggests using it as a green corrosion inhibitor for steel in a 1.0 N H₂SO₄ corrosive environment. The effectiveness of expired Tramadol as a corrosion inhibitor was evaluated using three analytical techniques: gravimetric, gasometric, and acidimetric techniques. The effects of expired drug doses (100–500 ppm), reaction temperature (303–333 K), and pH were investigated. The corrosion inhibition efficiency was found to increase with increasing the concentration and pH but decreased with increasing the temperature. The maximum inhibition of 93% was achieved by using 500 ppm of the expired medicinal drug inhibitor. It’s possible that the increased activation energy (E_a) for carbon steel in the presence of the expired pharmacological inhibitor than in the absence is due to physical adsorption. The increase in E_a can be explained to a significant drop in inhibitor adsorption on the carbon steel surface as temperature rises, resulting in a proportional increase in corrosion rates due to a larger area of the metal exposed to the acid environment. The decrease in carbon steel corrosion rate is primarily regulated by kinetic parameters of activation, as seen by the increase in ΔH_a with increasing inhibitor system concentrations for carbon steel corrosion. The inhibition was due to adsorption and adhesion of the drug constituents on the steel surface, and the adsorption was found to obey the Langmuir adsorption isotherm model. The techniques used are in good agreement (±2%), implying that expired Tramadol medicine could be used as a green corrosion inhibitor for steel in a 1.0 N H₂SO₄ acidic corrosive environment.

Keywords: expired drug, corrosion, Tramadol, green inhibitors, gravimetric, AAS, acidimetric

Int. J. Corros. Scale Inhib., 2022, 11, no. 3, 1282-1302
doi: 10.17675/2305-6894-2022-11-3-22

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