Comparative Study of S235 Steel Corrosion Inhibition by <i>Eucalyptus camaldulensis</i> and <i>Cyperus rotundus</i> Essential Oils in Hydrochloric Acid Solution

Abstract

Synthetic compounds certainly exhibit good anticorrosive activity but also toxicity for humans and their environment. Because of these concerns, we turned to more environmentally friendly substances such as essential oils and of course other types of plant extracts. These products are considered green corrosion inhibitors. In this present study, we propose to make a comparative study of the inhibitory effect of extracts of two different essential oils, Eucalyptus camaldulensis (EC) and Cyperus rotundus (CR) on the corrosion of structural steel S235 in the medium 1 M hydrochloric acid. This inhibitory action was studied using potentiodynamic polarization measurements and electrochemical impedance spectroscopy. The GC-MS analysis of the essential oils extracts showed that EC contains 96.2% oxygenated terpenes (90.6% monoterpenes and 5.6% sesquiterpenes), whereas CR includes 78.1% oxygenated terpenes (70.6% sesquiterpenes and 7.5% monoterpenes). Polarization measurements indicate that EC and CR are mixed inhibitors. The experimental results gave an inhibition efficiency close to 78.9% for EC and 86.7% for CR for an inhibitor concentration of 4 gL -1 at 293 K. The inhibition performances of these essential oils were correlated with their composition. The adsorption of the molecules of the oils responsible for the inhibition on the surface of the steel, in the hydrochloric acid solution, obeys the Langmuir adsorption isotherm. This present work has therefore shown that these two types of essential oils have a good inhibitory effectiveness on the corrosion of the metal S235 in 1M hydrochloric acid solution.

Chemical Composition and Antifungal Activity of Cyperus articulatus, Cyperus rotundus and Lippia alba Essential Oils against Aspergillus flavus Isolated from Peanut Seeds in Senegal

“…The other components in significant percent were longiverbenone (4.5%) and amorpha-4,7(11)-dien-3-one (3.4%). Similarly, high contents of humulene epoxide 2 (26.1%) and caryophyllene oxide (19.2%) have been reported for C. rotundus oils from Louga region in Senegal [29]. However, these compounds were at low levels or absent in essential oils of C. rotundus from Iran [30], India [31] and Brazil [31].…”

Evaluation of the inhibitory action of essential oil from Eucalyptus globulus leaves on the corrosion of mild carbon steel in 1M HCl medium

“…Various studies have also been carried out on the evaluation of the inhibitory efficiencies of natural compounds such as natural oils and essential oils extracted from various parts of plants, we can give the example of the work carried out by K. Cissé et al [12], on the evaluation of the inhibitory effectiveness of the essential oil of Cyperus articulatus on the corrosion of S235 steel in HCl medium and their studies resulted in an optimal inhibitory efficacy of 92%. Although other inhibitor types essential oils have been developed in recent years, such as Eucalyptus camaldulensis and Cyperus rotundus essential oils [13], but also chamomile essential oil [14], Mentha pulegium essential oil [15], prickly pear seed oil [16], essential oil extracted from Carum carvi L species [17], etc. In one of our previous works, we made an overview of most of the natural substances extracted from various parts of plants with rather high inhibition rates on different metallic materials in acidic medium [18].…”