Black Pine (Pinus nigra) Essential Oil as a Green Corrosion Inhibitor for Carbon Steel

In this work, the essential oil of black pine (Pinus nigra J. F. Arnold) was used for the first time as a natural, ecological, and sustainable corrosion inhibitor for the acid cleaning of carbon steel. The essential oil was extracted by hydrodistillation using a Clevenger-type apparatus, and the oil was analyzed by gas chromatography-flame-ionization detection (GC-FID) and gas chromatography-mass spectrometry (GC-MS). The most abundant components in the essential oil were alpha-pinene, germacrene D, (E)-cariophyllene, and beta-pinene. The inhibition efficiency was determined by electrochemical methods (electrochemical impedance spectroscopy and potentiodynamic polarization measurements). The results showed that the inhibitory efficiency of the black pine essential oil increases with time, reaching the highest values after 4 h of immersion for all inhibitor concentrations. It was also shown that black pine essential oil is a mixed-type inhibitor. The contact angle measurements confirmed that the black pine essential oil, as a new natural, environmentally safe inhibitor, is able to protect carbon steel from corrosion in a 1 M HCl solution.

Automated summary

In this research, black pine essential oil was utilized as a natural, ecological, and sustainable corrosion inhibitor for acid cleaning of carbon steel for the first time. The oil was extracted through hydrodistillation and analyzed using gas chromatography-flame-ionization detection (GC-FID) and gas chromatography-mass spectrometry (GC-MS). The major components found in the oil were alpha-pinene, germacrene D, (E)-caryophyllene, and beta-pinene. Electrochemical methods were employed to determine the inhibition efficiency. The results showed that the inhibitory efficiency of black pine essential oil increased over time, with the highest values observed after 4 hours of immersion for all inhibitor concentrations. It was also demonstrated that the oil acted as a mixed-type inhibitor and effectively protected carbon steel from corrosion in a 1 M HCl solution.