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Mentha pulegium extract as a natural product for the inhibition of corrosion. Part I: electrochemical studies a

a

a

Abdelkader Khadraoui , Abdellah Khelifa , Hocine Boutoumi & b

Belkheir Hammouti a

Laboratoire de Génie Chimique, Département de Chimie Industrielle, Faculté de Technologie, Université Saâd Dahlab de Blida, BP 270, Route de Soumaâ, Blida 09000, Algeria b

LCAE-URAC18, Faculté des Sciences, Université Mohammed Premier, Oujda, Morocco Published online: 22 May 2014.

To cite this article: Abdelkader Khadraoui, Abdellah Khelifa, Hocine Boutoumi & Belkheir Hammouti (2014) Mentha pulegium extract as a natural product for the inhibition of corrosion. Part I: electrochemical studies, Natural Product Research: Formerly Natural Product Letters, 28:15, 1206-1209, DOI: 10.1080/14786419.2014.919288 To link to this article: http://dx.doi.org/10.1080/14786419.2014.919288

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Natural Product Research, 2014 Vol. 28, No. 15, 1206–1209, http://dx.doi.org/10.1080/14786419.2014.919288

SHORT COMMUNICATION Mentha pulegium extract as a natural product for the inhibition of corrosion. Part I: electrochemical studies Abdelkader Khadraouia*, Abdellah Khelifaa, Hocine Boutoumia and Belkheir Hammoutib a

Laboratoire de Ge´nie Chimique, De´partement de Chimie Industrielle, Faculte´ de Technologie, Universite´ Saaˆd Dahlab de Blida, BP 270, Route de Soumaaˆ, Blida 09000, Algeria; bLCAE-URAC18, Faculte´ des Sciences, Universite´ Mohammed Premier, Oujda, Morocco

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(Received 5 November 2013; final version received 25 April 2014) The inhibitory effect of Mentha pulegium extract (MPE) on steel corrosion in 1 M HCl solution was investigated using potentiodynamic polarisation and electrochemical impedance spectroscopy. The inhibition efficiency of MPE was found to increase with the concentration and reached 88% at 33% (v/v). Polarisation measurements show that the natural extract acted as a mixed inhibitor. The remarkable inhibition efficiency of MPE was discussed in terms of blocking of electrode surface by adsorption of inhibitor molecules through active centres. The adsorption of MPE was found to accord with the Temkin isotherm. Keywords: natural plant; Mentha pulegium; extract; green inhibitor; adsorption; steel

1. Introduction Natural products were previously used as corrosion inhibitors for different metals in various environments (Khadraoui and Khelifa 2013; Khadraoui, Khelifa, Hamitouche, et al. 2014), and their optimum concentrations were reported. The obtained data showed that the plant extracts could serve as effective corrosion inhibitors and they have become important because they are environmentally acceptable, readily available and renewable source for a wide range of needed inhibitors. Plant extracts are viewed as an incredibly rich source of naturally synthesised chemical compounds that can be extracted by simple procedures with low cost. The extracts from the leaves, seeds, heartwood, bark, roots and fruits of plants have been reported to inhibit metallic corrosion in various acidic media (El-Etre et al. 2005; Okafor et al. 2005; Bouyanzer et al. 2006; Oguzie et al. 2006; Khadraoui et al. 2013). Mentha pulegium is a species of flowering plant in the family Lamiaceae. The leaves exhibit a very strong fragrance similar to spearmint. It is a traditional culinary herb, folk remedy and abortifacient. M. pulegium plants are sources of diverse classes of natural products such as flavonoids, alkaloids and essential oils (Lorenzo et al. 2002). All oils were found to be rich in oxygen monoterpene hydrocarbons especially menthol, menthone, 1,8-cineole, pulegone and p-menthan-3-one (Marzouk et al. 2007). In this work, the inhibitory action of M. pulegium extract (MPE) as a cheap, eco-friendly and naturally occurring substance on the corrosion behaviour of steel in 1 M HCl has been investigated through potentiodynamic polarisation and electrochemical impedance spectroscopy (EIS) methods.

*Corresponding author. Email: [email protected] q 2014 Taylor & Francis

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2. Results and discussion 2.1. Plant collection and extraction M. pulegium was collected during June 2009 in Ain-defla, north Algeria at 280 m altitude. The aerial parts of the plant were air-dried in the laboratory at room temperature. Stock solutions of the plant extract were prepared by extracting weighed amounts (10 g) of the powder of the dried leaves for 3 days in 1 M HCl at 298 K with continuous agitation. The solution was filtered and stored. The filtrates from both acid extractions had a reddish-brown appearance. From the stock solutions, inhibitor test solutions were prepared in the concentration range of 1– 50% (v/v).

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2.2. Polarisation curves Table 1 shows the fitting results of the polarisation curves obtained. Other electrochemical parameters and the inhibition efficiencies of extract can be determined from the corrosion current densities (Icorr) with and without inhibitors, which are also presented in Table 1. In this case, the inhibition efficiency is defined as follows:   I 0corr E% ¼ 1 2 £ 100; ð1Þ I corr 0 where Icorr and Icorr are current densities in the absence and presence of MPE, respectively. We 0 noted that Icorr and Icorr were calculated from the intersection of cathodic and anodic Tafel lines (Figure S1). From these values, it can be observed that, with the increase of the extract concentrations, both anodic and cathodic currents were inhibited. This result shows that the addition of the M. pulegium inhibitor reduced anodic dissolution and also retarded the hydrogen evolution reaction. The inspection of results in Table 1 indicates that the inhibition efficiency of the MPE is 88%. The free corrosion potential determined after 30 min of immersion does not change in the presence of the green inhibitor; thus, it can be classified as a mixed-type inhibitor.

2.3. EIS measurements The electrochemical impedance parameters derived from these investigations are mentioned in Table 2. The curves show a similar type of Nyquist plots for steel in the presence of various percentage concentration of inhibitor (Figure S2). The inhibition efficiency from the charge transfer resistance is calculated by E Rt % ¼

Rt 2 R0t £ 100; Rt

ð2Þ

Table 1. Electrochemical data for steel in 1 M HCl in the absence and presence of different percentage concentrations of MPE, and the corresponding inhibition efficiency. System Blank 6.25% MPE 12.5% MPE 25% MPE 33% MPE

Ecorr (mV/SCE)

Icorr (mA/cm2)

bc (mV/dec)

E (%)

2 504 2 497 2 499 2 500 2 501

422.3 220.9 208.1 133.6 49.22

115.4 140.7 141 138 144.5

– 47.69 50.72 68.63 88.34

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Table 2. Impedance parameters for corrosion of steel in 1 M HCl in the absence and presence of different percentage concentrations of MPE at 298 K. System

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Blank 6.25% MPE 12.5% MPE 25% MPE 33% MPE

Rt (V cm2)

E (%)

fmax (Hz)

Cdl (˛F/cm2)

62.63 116.8 122.2 207.7 457.3

– 46.37 48.74 69.84 86.30

25.82 45.39 49.08 100.81 146.01

98.46 30.03 26.55 7.60 2.38

where Rt and R0t are the charge transfer resistances in inhibited and uninhibited solutions, respectively. The charge transfer resistance (Rt) values are calculated from the difference in impedance at lower and higher frequencies (Tsuru et al. 1978) From the impedance data, we notice an increase in the charge transfer resistance and inhibition efficiency due to the formation of a protective surface film on the metal surface caused by the replacement of water molecules by the inhibitor molecules (Kertit and Hammouti 1996; Benalli et al. 2007; Khadraoui, Khelifa, Boutoumi, et al. 2014). While the decrease in the Cdl value can be attributed to a decrease in the local dielectric constant and/or an increase in the thickness of the electrical double layer as a consequence of the adsorption molecules of the extract (El-hajjaji et al. 2014). 3. Conclusion In this study, corrosion inhibition efficiency of MPE, in 1 M HCl medium was determined by potentiodynamic polarisation and electrochemical techniques. Results evidenced that this green inhibitor showed good performance (more than 88% at 33% percentage concentration of MPE) as corrosion inhibitors. Impedance studies revealed that the inhibitors reduced the corrosion rate by increasing the resistance of the system. Potentiodynamic polarisation studies confirmed that the inhibitor acted through mixed type of corrosion inhibition mechanism. The findings from this study suggest that the MPE is a potential eco-friendly corrosion inhibitor, which may be beneficial to related industries. Supplementary material Experimental material relating to this article are available online, alongside Figures S1 and S2. References Benalli O, Larabi L, Traisnel M, Gengembra L, Harek Y. 2007. Temperature effect on corrosion inhibition of carbon steel in formation water by non-ionic inhibitor. Appl Surf Sci. 253:6130–6139. Bouyanzer A, Hammouti B, Majidi L. 2006. Pennyroyal oil from Mentha pulegium as corrosion inhibitor for steel in 1 M HCl. Mater Lett. 60:2840–2843. El-Etre AY, Abdallah M, El-Tantawy ZE. 2005. Corrosion inhibition of some metals using Lawsonia extract. Corros Sci. 47:385–395. El-Hajjaji F, Zerga B, Sfaira M, Taleb M, Ebn Touhami M, Hammouti B, Al-Deyab SS, Benzeid H, Essassi El M. 2014. Comparative study of novel N-substituted quinoxaline derivatives towards mild steel corrosion in hydrochloric acid: Part 1. J Mater Environ Sci. 5:255–262. Khadraoui A, Khelifa A. 2013. Ethanolic extract of Ruta chalepensis as an eco-friendly inhibitor of acid corrosion of steel. Res Chem Intermed. 39:3937–3948. Khadraoui A, Khelifa A, Touafri L, Hamitouche H, Mehdaoui R. 2013. Acid extract of Mentha pulegium as a potential inhibitor for corrosion of 2024 aluminum alloy in 1 M HCl solution. J Mater Environ Sci. 4:663–670.

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Khadraoui A, Khelifa A, Hamitouche H, Mehdaoui R. 2014. Inhibitive effect by extract of Mentha rotundifolia leaves on the corrosion of steel in 1 M HCl solution. Res Chem Intermed. 40:961–972. Khadraoui A, Khelifa A, Boutoumi H, Hamitouche H, Mehdaoui R, Hammouti B, Al-Deyab SS. 2014. Adsorption and inhibitive properties of Ruta chalepensis L. oil as a green inhibitor of steel in 1 m hydrochloric acid medium. Int J Electrochem Sci. 9:3334–3348. Kertit S, Hammouti B. 1996. 1-Phenyl-5-mercapto-1,2,3,4-tetrazole as corrosion inhibitor of iron in 1 M HCl. Appl Surf Sci. 93:59– 66. Lorenzo D, Paz D, Dellacassa E, Davies P, Vila R, Canigueral S. 2002. Essential Oils of Mentha pulegium and Mentha rotundifolia from Uruguay. Bras Arch Boil Technol. 45:519–524. Marzouk Z, Marzouk B, Chraief I, Boukef K. 2007. Analysis of Tunisian Mentha pulegium L. oils from Monastir. Rev Reg Arides. 1:412–419. Oguzie EE, Onuchukwu AI, Okafor PC, Ebenso EE. 2006. Corrosion inhibition and adsorption behaviour of Ocimum basilicum extract on aluminum. Pigment Resin Tech. 35:63–70. Okafor PC, Ekpe UJ, Ebenso EE, Umoren EM, Leizou KE. 2005. Inhibition of mild steel corrosion in acidic medium of Sativum. Bull Electrochem. 21:347–352. Tsuru T, Haruyama S, Gijutsu B. 1978. Corrosion inhibition of iron by amphoteric surfactants in 2 M HCl. J Jpn Soc Corros Eng. 27:573–581.

Mentha pulegium extract as a natural product for the inhibition of corrosion. Part I: electrochemical studies.

The inhibitory effect of Mentha pulegium extract (MPE) on steel corrosion in 1 M HCl solution was investigated using potentiodynamic polarisation and ...
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