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Evaluation of the Performance of Sheng (Tragopogon Buphthalmos Boiss) Extract as a Green Corrosion Inhibitor in High Concentration Hydrochloric Acid Solutions

Bahramnejad, Hamed | 2021

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  1. Type of Document: M.Sc. Thesis
  2. Language: Farsi
  3. Document No: 53936 (07)
  4. University: Sharif University of Technology
  5. Department: Materials Science and Engineering
  6. Advisor(s): Afshar, Abdollah
  7. Abstract:
  8. In this study, the extract of Tragopogon buphthalmos Boiss was investigated as a green or environmentally friendly corrosion inhibitor for mild carbon steels in high concentration hydrochloric acid solutions. Tragopogon buphthalmos Boiss was extracted using the extraction method of digestion at 50 ° C assisted by ultrasonic bath. Water-ethanol-acetone solvents were used in ratios of 30:35:35, respectively. The ratio of plant volume to solvent volume was one to ten. The container containing the extract was placed in a bath water at 50 ° C until the extract was in the form of gum, then stored at -15 ° C In a freezer. Infrared Fourier transform spectroscopy (FTIR) was used to determine the composition of the extract. Visible-ultraviolet (UV-vis) spectroscopy test showed that the extract acted as a physical adsorption on the surface of steel samples. The immersion test was used to show the inhibition properties of the used extract in the acidic environment. By changing the test temperature in this test, the thermodynamic aspects of inhibitor performance were investigated. This test showed that the extract of Tragopogon buphthalmos Boiss plant was physically adsorbed on the surface. The efficiencies obtained from immersion test for 10%, 15% and 20% HCl acids were 94.6%, 95.8% and 96.1%, respectively. The potentiodynamic polarization electrochemical (PDP) test was used to prove the mechanism of function of inhibition as well as the cathodic or anodic, which showed that the mechanism was anodic-cathodic by blocking most of the anodic sites also, the ion of chlorine performed as a bridge to adsorption the molecule of the extract on the surface of mild steel. The efficiencies obtained from PDP test for 10%, 15% and 20% HCl acids were 95.2%, 95% and 94.2%, respectively. Electrochemical impedance spectroscopy (EIS) test has been used to investigate the operation and inhibition mechanism. The efficiencies obtained from this test for acids of 10%, 15% and 20% HCl acids were 94.7%, 97.2% and 91.8%, respectively. Surface studies were performed using optical microscopy (OM), scanning electron microscopy (SEM) and atomic force microscopy (AFM). The contact angle test was used to investigate the inhibitory effect on surface hydrophobicity, which showed the ability of the aqueous corrosive medium to separate from the metal surface
  9. Keywords:
  10. Corrosion Inhibitors ; Green Corrosion Inhibitor ; Hydrochloric Acid Inhibitor ; Biocompatible Corrosion Inhibitor ; Sheng Plant Extract

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