Corrosion Inhibition of Mild Steel and 304 Stainless Steel in 1 M Hydrochloric Acid Solution by Tea Tree Extract and Its Main Constituents

• Published in: Materials Vol. 14; no. 17; p. 5016
• Main Authors: Kim, Jae-Yeon, Shin, Inji, Byeon, Jai-Won
• Format: Journal Article
• Language: English
• Published: Switzerland MDPI AG 02.09.2021; MDPI
• Subjects: Antioxidants; Austenitic stainless steels; Chromatography; Constituents; Corrosion; corrosion inhibition; Corrosion inhibitors; Corrosion mechanisms; Corrosion prevention; Efficiency; Electrochemical impedance spectroscopy; Electrodes; Electrolytes; Fourier transforms; Hydrochloric acid; Hydroxyl groups; Infrared analysis; Infrared spectroscopy; Lasers; Low carbon steels; Mass spectrometry; Microscopy; Morphology; Phytochemicals; Pitting (corrosion); Raman spectra; Raman spectroscopy; Scientific imaging; Stainless steel; steel; Sulfur; Surface properties; Surface roughness; tea tree extract; Terpineol; Trees; Uniform attack (corrosion); United States > US; raman spectroscopy; steel; tea tree extract; corrosion inhibition
• ISSN: 1996-1944; 1996-1944
• DOI: 10.3390/ma14175016

Tea tree extract, containing antioxidant constituents α-terpineol, terpinen-4-ol, and α-terpinene, has a wide range of applications in the cosmetic, food, and pharmaceutical industries. In this study, tea tree extract showed an anticorrosive effect under 1 M HCl solution on mild steel (MS) and 304 stainless steel (STS). Uniform corrosion for MS and pitting corrosion for STS at 298 K were retarded, with inhibition efficiencies of 77% and 86%, respectively. The inhibition of uniform and pitting corrosion was confirmed by scanning electron microscopy and laser scanning confocal microscopy in terms of surface roughness and pitting morphologies. The most effective constituent contributing to the inhibitory performance of tea tree extract was revealed to be α-terpineol, with an inhibition efficiency of 83%. The adsorption of tea tree extract was confirmed by surface characterization analysis using Fourier transform infrared spectroscopy, Raman spectroscopy, and Electrochemical impedance spectroscopy. Interestingly, G- and D-peaks of Raman spectra were detected from the inhibited steels, and this finding is the first example in the corrosion inhibition field. The anticorrosion mechanism can be explained by the formation of organic-Fe complexes on the corroded steel surface via electron donor and acceptor interactions in the presence of an oxygen atom of the hydroxyl group or ether of organic inhibitors.