Eco-Friendly Corrosion Inhibition of Pipeline Steel Using <i>Brassica oleracea</i>

Ngobiri, N. C.; Oguzie, E. E.; Li, Y.; Liu, L.; Oforka, N. C.; Akaranta, O.

doi:https://doi.org/10.1155/2015/404139

International Journal of Corrosion

On this page

Abstract Introduction Experimental Results and Discussion Conclusion Acknowledgments References Copyright Related Articles

Research Article | Open Access

Volume 2015 | Article ID 404139 | https://doi.org/10.1155/2015/404139

Eco-Friendly Corrosion Inhibition of Pipeline Steel Using Brassica oleracea

N. C. Ngobiri,^1,2E. E. Oguzie,³Y. Li,²L. Liu,²N. C. Oforka,¹and O. Akaranta¹

Academic Editor: Ramazan Solmaz

Received24 Jul 2014

Revised04 Jan 2015

Accepted08 Jan 2015

Published19 Feb 2015

Abstract

The inhibition capacity of Brassica oleracea (BO) extract on the corrosion of pipeline steel in 0.5 M H₂SO₄ was evaluated using electrochemical techniques. The results showed an excellent inhibition efficiency which increased with initial increase in extract concentration and temperature to a point and decreased with further increase in BO extract concentration and temperature. Mixed inhibition behaviour was proposed for the action of BO. The unique behaviour of BO was attributed to the organic entities present in the extract.

1. Introduction

Steel pipes are widely used to transport industrial fluids. The operation of these pipes involves acid pickling, acid descaling, oil well acidification, and so forth. These operations result in increased corrosion damage due to the aggressive nature of industrial chemicals and environment. The application of chemical substances as corrosion inhibitors has received several research attentions [1–5].

The inside of pipelines is usually subject to a flow regime and injecting corrosion inhibitors is a practical method of corrosion control [6]. Corrosion inhibitors are mostly organic and inorganic in nature. Structurally, organic corrosion inhibitors consist of polar and nonpolar ends. The polar end, which consists of heteroatoms such as oxygen, nitrogen, and sulphur, is usually adsorbed on the electrovalent metal surface. The heteroatoms usually have extra outer electrons to fill or share with the vacant d-orbital of the metal [7–10].

There are environmental issues associated with the application of most inhibitors as some are toxic to the ecosystem. Plants extracts are eco-friendly and have been found to contain phytochemical constituents with similar characteristics to organic corrosion inhibitor; hence, their applicability as inhibitors has been reported [11–15]. The constituent compounds present in the plant biomass may antagonize or synergize to give the resultant corrosion inhibition efficiency [16–18]. The use of wastes from plants as corrosion inhibitors can be another way of extending the beneficial use of these plants and so enhance municipal waste management.

A lot of research has been carried out on the chemical composition of Brassica oleracea and steel [19–21]. Internal leaves of BO have shown high antioxidant capacity. Analysis of the methanoic extract of BO leaves using GC-MS identified 44 compounds that exhibited antimicrobial activity [22].

The present work aims at the development of eco-friendly corrosion inhibitor and proposing the use of parts of beneficial plants usually discarded as waste. The mechanism of nondirect proportionality between corrosion inhibitor concentration and percentage inhibition efficiency is proposed.

2. Experimental

2.1. Plant Collection and Extraction

The outer leaves of Brassica oleracea were washed and air-dried. The dried leaves were pulverized using an electric blender. About 500 g of the dried sample was soaked in 99% ethanol (analytical grade) in 1000 mL volumetric flask. Sufficient quantity of ethanol was added to cover the surface of the sample. The flask was covered and left for 48 hours. The content of the flask was filtered and the filtrate concentrated using rotary evaporator. The dried residue was stored in an air tight analytical container. Appropriate quantities were subsequently weighed to make desired concentrations of the inhibitor solution.

2.2. Electrochemical Measurements

The electrochemical determinations were carried out using a conventional three-electrode cell with a platinum counter electrode, a saturated calomel electrode (SCE) coupled to a fine Luggin capillary as reference electrode. Pipeline steel was used as the working electrode (WE) and has the composition shown in Table 1. The WE was embedded in a Teflon holder using epoxy resin. The edges were sealed with hydrocarbon wax to expose an area of 1 cm². The WE was prepared before the experiment by polishing with different grades of emery paper (150, 400, 800, 1000, and 2000), cleaned with distilled water, degreased with acetone, dried, and stored in a moisture-free desiccator. All the experiments were carried out at open circuit potential (OCP) for 30 min to attain a stable potential, while the corrosive environment temperature was maintained using a thermostat water bath. The experiments were all carried out using a Perstat 2273 Advanced Electrochemical system. Each experiment was repeated three times to ensure reproducibility.

The potentiodynamic polarization measurement was started at the cathodic potential of −250 mV to anodic potential of +250 mV at a scan rate of 1 mV s⁻¹. Corrosion current density (), equilibrium corrosion potential (), and other kinetic parameters were extrapolated using the power suite software. Corrosion inhibition efficiency was calculated from values by applying the following relationship: where and are corrosion current densities in the uninhibited and inhibited systems, respectively.

The electrochemical impedance spectroscopy (EIS) experiments were carried out between frequencies of 100 kHz and 10 mHz using a signal of 10 mV amplitude. The cell was allowed to achieve a stable open circuit potential before the EIS test. Electrochemical data were analyzed using ZSimpWin software. The corrosion inhibition efficiency was calculated by applying the charge transfer resistance with the relationship where and are the charge transfer resistance in the presence and absence of BO extract, respectively.

2.3. Surface Morphology

Surface morphology studies were carried out using Oxford x-Max scanning electron microscope (SEM). The test pipeline steel coupons were prepared as described for the electrochemical experiment above. A coupon was immersed in 0.5 M sulphuric acid while the second coupon was immersed in a solution of 0.5 M sulphuric acid with 0.1 g/L Brassica oleracea extract for 8 hours. The coupons were retrieved, rinsed, dried, and subjected to SEM examination.

2.4. Fourier Transform Infrared Spectroscopy

The pipeline steel specimens were immersed in 0.5 M sulphuric acid with 0.1 g/L Brassica oleracea extract for 24 hours. The steel samples were taken out and dried. The nature of the surface film formed and the presence of functional groups in the Brassica oleracea extract in the corrosion product were tested by Magna-IR 560 Spectrometer ESP Nicolet with the aid of KBr disc provided by the instrument. These were compared with the FTIR of Brassica oleracea extract [23].

3. Results and Discussion

3.1. Potentiodynamic Polarization

The polarization curves obtained for pipeline steel in 0.5 M H₂SO₄ with and without concentrations of Brassica oleracea extract at 303 K are presented in Figure 1. The kinetic parameters, corrosion potential (), corrosion current density (), cathodic Tafel slope (), anodic Tafel slope (), and inhibition efficiency (), associated with Figure 1 are presented in Table 2. From Figure 1, the presence of BO extract reduced the cathodic current, while Table 1 indicates a reduction in both the cathodic and anodic current with the resultant corrosion current density in the presence of BO. The corrosion inhibition efficiency of Brassica oleracea reached a value of 98.31% at 0.1 g/L within the experimental condition. The inhibition efficiency later decreased to 93.48% at the concentration of 1.0 g/L. From Table 2, BO can be classified as a mixed type inhibitor because it was able to reduce both the cathodic and anodic current. This trend has been reported by other researchers [24, 25]. Also, Table 2 indicates a change in less than 85 mV. An inhibitor is classified as an anodic-type or cathodic-type inhibitor when the change in is greater than 85 mV [24–26].

Figure 2 presents the potentiodynamic polarization curve for pipeline steel in 0.5 M H₂SO₄, with and without concentrations of Brassica oleracea at 313 K. The parameters for Figure 2 are presented in Table 3. The anodic inhibiting effect appears to become more pronounced with rise in temperature. The shift in the , though still less than 85 Mv, was shifted more towards the anodic region. There was a further reduction in the value of the corrosion current density and consequent increase in corrosion inhibition efficiency to 99.63% at 313 K.

Figures 3 and 4 present the plot of pipeline steel in 0.5 M H₂SO₄ with and without concentrations of Brassica oleracea extract at 323 K and 333 K, respectively. Tables 4 and 5 present the extracted kinetic parameters from Figures 3 and 4, respectively. The optimal inhibition performance of the extract was recorded at 0.1 g/L extract concentration at 313 K. This may be attributed to the optimization of the bonding interaction of the molecular components of Brassica oleracea with the metal surface d-orbitals. The multi-phytochemical components of BO extract gave the highest inhibition efficiency and surface coverage at 0.1 g/L and 313 K. It may be assumed that this is the condition for optimal corrosion inhibition performance and surface coverage. At other experimental conditions, optimal metal-inhibitor bonding may not have been attained because of stearic hindrance.

3.2. Impedance Spectroscopy

Figures 5(a), 6, 7, and 8 present the electrochemical impedance EIS Nyquist plots for pipeline steel in 0.5 M H₂SO₄ with and without concentrations of Brassica oleracea extract at 303, 313, 323, and 333 K, respectively. Researchers have used EIS to investigate the corrosion inhibition mechanism at the metal/electrolyte interfaces, since it provides information on the resistive and capacitive behavior at the interface [26–28].

(a)

(b)

(c)

The Nyquist plots show a series of depressed semicircles with center under the real axis. This behavior is characteristic of solid electrode, indicating frequency distribution of impedance data and results from roughness and heterogeneous nature of solid electrodes [29, 30]. Figures 5(a), 6, 7, and 8 are characterized by double time constants, the high frequency capacitive loop, and the low frequency inductive loop. The high frequency capacitive loop is attributed to the charge transfer process (charge transfer resistance ) of the corrosion reaction. The of an alloy is usually a composite value, but steel is an alloy predominated by iron, so its is governed mainly by the dissolution of iron [31]. Researchers have attributed the low frequency inductive loop to surface relaxation due to adsorption of reaction intermediates [32, 33] and hydrogen [34] on the oxide film on the electrode.

The equivalent circuit shown in Figure 5(b) was used to analyze the impedance response in Figure 5(a). The circuit parameters of the oxide film can be represented as a parallel circuit of resistor and capacitor as in the impedance plot. In a nonideal situation, the capacitance is replaced by a constant phase element (CPE) [24, 35]. The circuit comprises a parallel arrangement of two resistors in a series relationship to another resistor, an inductor, and a constant phase element. The impedance () of CPE can be represented as follows [36]: where is a proportional factor and has the meaning of a phase shift. When , CPE represents a resistance, when , a capacitance, when , an inductance, and when , a Warburg element, is the angular frequency (rad s⁻¹), and is an imaginary number. The double-layer capacitance () can be calculated from where is the frequency at which the imaginary part of the impedance has a maximum.

The pattern of the impedance plot with and without varying concentrations of BO extract is similar suggesting that BO does not change the mechanism of corrosion under the experimental conditions. The impedance parameters such as the and at 303 K were determined using the ZSimpWin software by fitting to the equivalent circuit model R(QR(LR)) and presented in Table 6. Figure 5(c) presents a plot of the ZSimpWin plot of experimental and computer data for the impedance response of pipeline steel in 0.5 M H₂SO₄ with 0.1 g/L BO. The plot shows that the impedance data of BO is well fitted into the model.

Table 6 indicates that the value of the charge transfer resistance increased with increase in Brassica oleracea extract concentration getting to peak in 0.1 g/L concentration. This is almost in agreement with the potentiodynamic polarization result. The slight difference in IE% of both methods can be attributed to change in the exact time of carrying out both measurements because corrosion potential changes with time. Also the value of CPE decreased reaching a minimum of 4.5 × 10⁻⁵ at 0.1 g/L. Both trends suggest that the surface roughness of pipeline steel in the presence of the extract inhibitor decreased due to adsorbed Brassica oleracea extract on the pipeline steel surface. These increased the inhibitor film at the metal-acid interface thereby inhibiting the corrosion of pipeline steel in sulphuric acid environment [36, 37].

Figure 9 presents the Nyquist plot for time effect of pipeline steel in 0.5 M H₂SO₄ with 0.1 M g/L Brassica oleracea extract for six days. The high frequency semicircle increased in diameter for the first four days before decreasing and increasing on the fifth and sixth day, respectively. The increase in the charge transfer resistance between day one and day four indicates an increased adsorption of Brassica oleracea extract with time. This implies that BO extracts increase in its corrosion inhibition efficiency with time.

3.3. Corrosion Surface Morphology

Figure 10 presents image of the corrosion surface morphology of pipeline steel immersed in (a) 0.5 M H₂SO₄ and (b) 0.5 M H₂SO₄ with 0.1 g/L BO extracts after 8 hours of immersion. The sulfuric acid aggressively corroded the sample in Figure 10(a) causing a rougher surface. The contrast was noticed in the sample in Figure 10(b) with smoother surface. The sample in Figure 10(b) surface is attributed to the ability of Brassica oleracea extract to form an adsorbed film on the surface of pipeline steel which was absent in Figure 10(a) sample. This is in agreement with the impedance results. The slight damage in sample in Figure 10(b) might have occurred due to the following reasons. (a) It has been proposed that the water molecules first get adsorbed at the metal/electrolyte interface before the inhibitor molecules displace them to get adsorbed at the metal surface [38]. The change in potential by the time the water molecules are at the surface of the metal without BO is a potential stage of corrosion damage. This could also be explained to result from the differential in the rate different molecules in the extract get adsorbed and stabilize at the surface due different molecular properties. (b) Since the inhibition efficiency is not 100%, it could have corroded in the presence of BO extract.

(a)

(b)

3.4. Fourier Transform Infrared Spectroscopy Spectra

The FTIR spectra of Brassica oleracea corrosion product from pipeline steel surface presented in Figure 11 were compared with those of Brassica oleracea previously reported [23]. The FTIR spectrum of Brassica oleracea is similar to the FTIR of Brassica oleracea film on pipeline steel surface, in range of 500–3500 cm⁻¹ indicating the presence of similar functional groups. It has peaks at 3330, 1635, 1418, and 1054 cm⁻¹. These peaks show the presence of –OH, –COOH, –NH, and C=O groups, respectively. The deviations are attributed to the formation of complex between iron and functional groups present in the BO extract. Similar deviation has been previously reported [39].

The [Fe-BO extract functional groups]²⁺ may be a stable complex adsorbed on the pipeline steel surface, forming covalent or coordinate bonds between the anionic components of BO extracts and vacant Fe d-orbital. The metal-inhibitor bond usually leads to corrosion inhibition through adsorption [40]. Also, the Fe-BO extract functional groups complex may be a soluble complex leading to a catalytic effect, thus accelerating corrosion. The plant extract biomass is composed of many chemical compounds with a probability of both mechanisms operating concurrently. The inhibiting effect of Brassica oleracea can be attributed to the resultant effect of both corrosion accelerating and retarding mechanisms. The corrosion retarding mechanism through stable complex formation dominates at increasing concentration till a critical concentration is reached where formation of soluble complex dominates. This trend has been previously reported [18].

4. Conclusion

The extract from BO showed excellent corrosion inhibition characteristics for pipeline steel corrosion in acidic environment. The anticorrosion activities of BO plant extract are attributed to its multiconstituents. The resultant interaction between the multiconstituents of BO accounts for its high inhibition performance.

The extract of BO is a mixed-type corrosion inhibitor for pipeline steel in 0.5 M H₂SO₄. The inhibition of BO is through the formation of an adsorbed corrosion retarding complex of Fe and molecular components in BO [Fe-BO molecules] and an unstable soluble corrosion accelerating complex.

Conflict of Interests

The authors declare that there is no conflict of interests regarding the publication of this paper.

Acknowledgments

N. C. Ngobiri is grateful to Tertiary Education Trust Fund, Nigeria, for financial support and State Key Laboratory for Corrosion and Protection, Institute of Metal Research, China, for research placement.

References

W. Villamizar, M. Casales, J. G. Gonzales-Rodriguez, and L. Martinez, “An EIS study of the effect of the pedant group in imidazolines as corrosion inhibitors for carbon steel in CO₂ environments,” Materials and Corrosion, vol. 57, no. 9, pp. 696–704, 2006.
View at: Publisher Site | Google Scholar
F. M. Donahue and K. Nobe, “Theory of organic corrosion inhibition,” Journal of the Electrochemical Society, vol. 112, no. 9, pp. 886–891, 1965.
View at: Publisher Site | Google Scholar
D. Wang, S. Li, Y. Ying, M. Wang, H. Xiao, and Z. Chen, “Theoretical and experimental studies of structure and inhibition efficiency of imidazoline derivatives,” Corrosion Science, vol. 41, no. 10, pp. 1911–1919, 1999.
View at: Publisher Site | Google Scholar
F. F. Eliyan, E.-S. Mahdi, Z. Farhat, and A. Alfantazi, “Interpreting the passivation of HSLA steel from Electrochemical corrosion investigation in bicarbonate-oil aqueous emulsion,” International Journal of Electrochemical Science, vol. 8, no. 2, pp. 3026–3038, 2013.
View at: Google Scholar
J. Telegdi, A. Shaban, and E. Kálmán, “EQCM study of copper and iron corrosion inhibition in presence of organic inhibitors and biocides,” Electrochimica Acta, vol. 45, no. 22, pp. 3639–3647, 2000.
View at: Publisher Site | Google Scholar
N. C. Ngobiri, O. Akaranta, N. C. Oforka, E. E. Oguzie, and S. U. Ogbulie, “Inhibition of pseudo-anaerobic corrosion of oil pipelines water using biomas-derived molecules,” Advances in Materials and Corrosion, vol. 2, pp. 20–25, 2013.
View at: Google Scholar
M. A. Quraishi, M. Z. A. Rafiquee, S. Khan, and N. Saxena, “Corrosion inhibition of aluminium in acid solutions by some imidazoline derivatives,” Journal of Applied Electrochemistry, vol. 37, no. 10, pp. 1153–1162, 2007.
View at: Publisher Site | Google Scholar
S. K. Shukla and M. A. Quraishi, “4-Substituted anilinomethylpropionate: new and efficient corrosion inhibitors for mild steel in hydrochloric acid solution,” Corrosion Science, vol. 51, no. 9, pp. 1990–1997, 2009.
View at: Publisher Site | Google Scholar
C. Cao, “On electrochemical techniques for interface inhibitor research,” Corrosion Science, vol. 38, no. 12, pp. 2073–2082, 1996.
View at: Publisher Site | Google Scholar
G. Moretti, F. Guidi, and G. Grion, “Tryptamine as a green iron corrosion inhibitor in 0.5 M deaerated sulphuric acid,” Corrosion Science, vol. 46, no. 2, pp. 387–403, 2004.
View at: Publisher Site | Google Scholar
P. B. Raja and M. G. Sethuraman, “Inhibitive effect of black pepper extract on the sulphuric acid corrosion of mild steel,” Materials Letters, vol. 62, no. 17-18, pp. 2977–2979, 2008.
View at: Publisher Site | Google Scholar
P. C. Okafor, M. E. Ikpi, I. E. Uwah, E. E. Ebenso, U. J. Ekpe, and S. A. Umoren, “Inhibitory action of Phyllanthus amarus extracts on the corrosion of mild steel in acidic media,” Corrosion Science, vol. 50, no. 8, pp. 2310–2317, 2008.
View at: Publisher Site | Google Scholar
A. Y. El-Etre, “Khillah extract as inhibitor for acid corrosion of SX 316 steel,” Applied Surface Science, vol. 252, no. 24, pp. 8521–8525, 2006.
View at: Publisher Site | Google Scholar
E. E. Oguzie, “Inhibition of acid corrosion of mild steel by Telfaria occidentalis extract,” Pigment & Resin Technology, vol. 34, no. 6, pp. 321–326, 2005.
View at: Publisher Site | Google Scholar
A. M. Abdel-Gaber, E. Khamis, H. Abo-ElDahab, and S. Adeel, “Inhibition of aluminium corrosion in alkaline solutions using natural compound,” Materials Chemistry and Physics, vol. 109, no. 2-3, pp. 297–305, 2008.
View at: Publisher Site | Google Scholar
Z. Ghasemi and A. Tizpar, “The inhibition effect of some amino acids towards Pb-Sb-Se-As alloy corrosion in sulfuric acid solution,” Applied Surface Science, vol. 252, no. 10, pp. 3667–3672, 2006.
View at: Publisher Site | Google Scholar
H. Ashassi-Sorkhabi and D. Seifzadeh, “The inhibition of steel corrosion in hydrochloric acid solution by juice of Prunus cerasus,” International Journal of Electrochemical Science, vol. 1, no. 2, pp. 92–98, 2006.
View at: Google Scholar
A. M. Abdel-Gaber, B. A. Abd-El-Nabey, I. M. Sidahmed, A. M. El-Zayady, and M. Saadawy, “Inhibitive action of some plant extracts on the corrosion of steel in acidic media,” Corrosion Science, vol. 48, no. 9, pp. 2765–2779, 2006.
View at: Publisher Site | Google Scholar
F. Ferreres, C. Sousa, V. Vrchovská et al., “Chemical composition and antioxidant activity of tronchuda cabbage internal leaves,” European Food Research and Technology, vol. 222, no. 1-2, pp. 88–98, 2006.
View at: Publisher Site | Google Scholar
R. Font, M. Rio-Celestino, E. Rosa, and A. Haro-Bailon, “Genetic variation for plant breeding,” in Proceedings of the 17th EUCARPIA General Congress, p. 463, Tulln, Austria, September 2004.
View at: Google Scholar
J. D. Lee, Concise Inorganic Chemistry, Wiley India Private Limited, New Delhi, India, 5th edition, 2008.
M. A. Hoss and A. Rahman, “Chemical composition of bioactive compounds by GC-MS screening and anti-fungal properties of the crude extracts of cabbage samples,” Asian Journal of Biotechnology, vol. 3, no. 1, pp. 68–76, 2011.
View at: Publisher Site | Google Scholar
A. Rameeja Begum and M. Poonkothai, “In vitro antimicrobial activity and phytochemical analysis of Brassica oleracea,” International Journal of Pharmacy and Pharmaceutical Sciences, vol. 5, no. 2, pp. 404–408, 2013.
View at: Google Scholar
J. Huang, H. Cang, Q. Liu, and J. Shao, “Environment friendly inhibitor for mild steel by Artemisia halodendron,” International Journal of Electrochemical Science, vol. 8, no. 6, pp. 8592–8602, 2013.
View at: Google Scholar
W.-H. Li, Q. He, S.-T. Zhang, C.-L. Pei, and B.-R. Hou, “Some new triazole derivatives as inhibitors for mild steel corrosion in acidic medium,” Journal of Applied Electrochemistry, vol. 38, no. 3, pp. 289–295, 2008.
View at: Publisher Site | Google Scholar
P. C. Okafor and Y. Zheng, “Synergistic inhibition behaviour of methylbenzyl quaternary imidazoline derivative and iodide ions on mild steel in H₂SO₄ solutions,” Corrosion Science, vol. 51, no. 4, pp. 850–859, 2009.
View at: Publisher Site | Google Scholar
K. Kavipriya, J. Sathiyabama, S. Rajendran, and R. Nagalakshmi, “The inhibitive effect of diethylenetriamine-pentaamethylenephosphonic acid on the corrosion of carbon steel in sea water,” European Chemical Bulletin, vol. 2, no. 7, pp. 423–429, 2013.
View at: Google Scholar
P. P. Raymond, P. P. Regis, S. Rajendran, and M. Manivannan, “Investigation of corrosion of stainless steel by sodium tungstate,” Research Journal of Chemical Sciences, vol. 3, no. 2, pp. 54–58, 2013.
View at: Google Scholar
T. Pajkossy, “Impedance of rough capacitive electrodes,” Journal of Electroanalytical Chemistry, vol. 364, no. 1-2, pp. 111–125, 1994.
View at: Publisher Site | Google Scholar
S. S. A. Rehim, O. A. Hazzazi, M. A. Amin, and K. F. Khaled, “On the corrosion inhibition of low carbon steel in concentrated sulphuric acid solutions. Part I: chemical and electrochemical (AC and DC) studies,” Corrosion Science, vol. 50, no. 8, pp. 2258–2271, 2008.
View at: Publisher Site | Google Scholar
M. Keddam, O. R. Mattos, and H. Takenouti, “Reaction model for iron dissolution studied by electrode impedance I. Experimental results and reaction model,” Journal of the Electrochemical Society, vol. 128, no. 2, pp. 257–266, 1981.
View at: Publisher Site | Google Scholar
K. F. Khaled, “Corrosion control of copper in nitric acid solutions using some amino acids—a combined experimental and theoretical study,” Corrosion Science, vol. 52, no. 10, pp. 3225–3234, 2010.
View at: Publisher Site | Google Scholar
C. M. A. Brett, “On the electrochemical behaviour of aluminium in acidic chloride solution,” Corrosion Science, vol. 33, no. 2, pp. 203–210, 1992.
View at: Publisher Site | Google Scholar
R. F. A. Jargelius-Pettersson and B. G. Pound, “Examination of the role of molybdenum in passivation of stainless steels using AC impedance spectroscopy,” Journal of the Electrochemical Society, vol. 145, no. 5, pp. 1462–1469, 1998.
View at: Publisher Site | Google Scholar
R. Z. Zand, K. Verbeken, and A. Adriaens, “Evaluation of the corrosion inhibition performance of silane coatings filled with cerium salt-activated nanoparticles on hot-dip galvanized steel substrates,” International Journal of Electrochemical Science, vol. 8, no. 4, pp. 4924–4940, 2013.
View at: Google Scholar
H. Cang, Z. H. Fei, J. L. Shao, W. Y. Shi, and Q. Xu, “Corrosion inhibition of mild steel by Aloes extract in HCL solution medium,” International Journal of Electrochemical Science, vol. 8, no. 1, pp. 720–734, 2013.
View at: Google Scholar
G. Ji, S. K. Shukla, E. E. Ebenso, and R. Prakash, “Argemone mexicana leaf extract for inhibition of mild steel corrosion in sulfuric acid solutions,” International Journal of Electrochemical Science, vol. 8, no. 8, pp. 10878–10889, 2013.
View at: Google Scholar
J. O. M. Bockris and D. A. J. Swinkels, “Adsorption of n-decylamine on solid metal electrodes,” Journal of The Electrochemical Society, vol. 111, no. 6, pp. 736–743, 1964.
View at: Publisher Site | Google Scholar
M. Sangeetha, S. Rajendran, J. Sathiyabama et al., “Corrosion inhibition by an aqueous extract of Phyllanthus amarus,” Portugaliae Electrochimica Acta, vol. 29, no. 6, pp. 429–444, 2011.
View at: Publisher Site | Google Scholar
O. Benali, H. Benmehdi, O. Hasnaoui, C. Selles, and R. Salghi, “Green corrosion inhibitor: inhibitive action of tannin extract of Chamaerops humilis plant for the corrosion of mild steel in 0.5M H₂SO₄,” Journal of Materials and Environmental Science, vol. 4, no. 1, pp. 127–138, 2013.
View at: Google Scholar

Copyright

Copyright © 2015 N. C. Ngobiri et al. This is an open access article distributed under the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.

PDF Download Citation

Download other formats

Order printed copies

Views

4196

Downloads

1918

Citations