International Journal of ElectrochemistryVolume 2011 (2011), Article ID 157576, 8 pagesdoi:10.4061/2011/157576

Research Article

Inhibition Effect of Miconazole Nitrate on the Corrosion of Mild Steel in Hydrochloric Acid Medium

J. Ishwara Bhat¹ and Vijaya D. P. Alva²

¹Department of Chemistry, Mangalore University, Mangalagangotri, Karnataka 574199, India²Department of Chemistry, Shree Devi Institute of Technology, Karnataka 575003, India

Received 17 November 2010; Revised 30 April 2011; Accepted 10 May 2011

Academic Editor: Gerd-Uwe Flechsig

Copyright © 2011 J. Ishwara Bhat and Vijaya D. P. Alva. This is an open access article distributed under the Creative Commons Attribution License, which permits unrestricted use, distribution, reproduction in any medium, provided the original work is properly cited.

Abstract.

The corrosion inhibition of mild steel by miconazole nitrate, an antifungal drug has been investigated using potentiodynamic polarization, electrochemical impedance spectroscopy technique, and weight loss methods. The experimental results suggested miconazole nitrate is a good corrosion inhibitor for mild steel in 1 M hydrochloric acid medium. The inhibition efficiency increased with increase in inhibitor concentration. The thermodynamic parameters were determined and discussed. The inhibition was assumed to occur via adsorption of the inhibitor molecule on the surface of mild steel following Langmuir adsorption isotherm.

1. Introduction

The corrosion of metals has received prime attention of material scientists and chemists since it has many serious adverse effects including economic, health, safety, technological, and cultural consequences. Corrosion of mild steel is one of the major areas of concern in many industries, where acids are widely used for applications such as acid pickling, acid descaling, and oil well acidizing. Due to general aggressiveness of acid solutions, respective materials of constructions are getting corroded easily. Development of methods to control such corrosion is a challenge to chemists and scientists, working in this area. A large number of methods have been employed to understand the practical problem and its control.

Inhibition is one of the most important applications in the corrosion protection. The use of specific chemical compound as an inhibitor is the best, simple, and practical method to minimize corrosion of metals. The corrosion inhibitors bring down the rate of corrosion to a greater extent even when added in small quantities to the corrosive environment. Inhibitors protect the metals by getting effectively adsorbed on its surface, blocking the active sites of metal dissolution and/or hydrogen evolution, there by retarding overall metal corrosion in aggressive environment. Organic molecules could be adsorbed on the metal surface by one of the following four mechanisms: (a) electrostatic interaction between charged surface of the metal and the charge of the inhibitor, (b) interaction of unshared electron pairs in the inhibitor molecule with the metal, (c) interaction of electron with the metal, and (d) a combination of the (a–c) types. Selecting an appropriate inhibitor for a specific environment and the corroding metal is of great importance, since an inhibitor that protects one particular metal may accelerate the corrosion of other. Many heterocyclic compounds containing hetero atoms like N, O, and S have been proved to be effective inhibitors for corrosion of metals in acidic media [1–11]. An assortment of organic compounds having two or more hetero atoms such as N, O, S and multiple bonds in their molecular structure are of particular interest because of their better inhibition efficiency as compared to those containing N or S alone [12]. Most of the inhibitors are toxic and environmentally hazardous. Due to this, interest is still growing to exploit environmentally acceptable corrosion inhibitors. Use of few antibacterial and antifungal drugs has been reported by some investigators [13–16]. Miconazole nitrate (Figure 1) is an azole antifungal drug [17], used in topical antifungal medications for athlete's foot, ringworm, jock itch, and perioral candidiasis [18–20]. Miconazolenitrate is the commercial name of [(1-(2-(2,4-dichlorobenzyloxy)-2-(2,4-dichlorophenyl)ethyl)-1H-imidazole. nitrate]. Perusals of several literatures reveal that there is no information regarding the use of miconazole nitrate as corrosion inhibitor for mild steel. The aim of the present investigation is to study the effect of miconazole nitrate as a potential inhibitor for mild steel in 1 M HCl.

Figure 1: Molecular structure of miconazole nitrate inhibitor.

2. Experimental

IS-2062 mild steel samples of Tata steel provided by ABCO Steel International Ltd. Mangalore were used in the present study. The chemical composition of IS-2062 is (wt%): C (0.18%), Mn (0.6%), S (0.05%), P (0.04%), Si (0.1%), and Fe (balance). Test materials were abraded with different emery papers up to 1000 grade, cleaned with acetone, washed with double distilled water, and properly dried prior to exposure. Analar grade HCl and double distilled water were used to prepare all solutions. Miconazole nitrate (F.W. 479.139) from Frapps Chemical Reagent Co. Ltd.) was used for the study.

Weight loss measurements were performed on mild steel coupons with dimensions inches, immersed in 100 mL flask, containing 50 mL of 1 M hydrochloric acid solution with different concentrations of the inhibitor. There was neither agitation nor exposure to oxygen during weight loss measurement. Weight loss of the metal coupons were noted after an immersion period of 24 hours at temperatures ranging from 30°C to 60°C.

Electrochemical tests were carried out with a CH-analyzer model, CH1660D. The cell arrangement used was a conventional three-electrode cell with platinum counter electrode, saturated calomel electrode as reference electrode, and test material (mild steel) as working electrode. The test material was covered by epoxy adhesive-araldite so that only 1 cm² area was in contact with the solution. Polarization curves were recorded potentiodynamically, at the scan rate of 1 mV/s, in the range of +250 mV to −250 mV versus OCP potential. Impedance was measured over a frequency range of 1 MHz to 0.05 Hz using amplitude of 10 mV peak to peak using AC signal.

3. Results and Discussion

3.1. Polarization Measurements

Figure 2 shows the potentiodynamic polarization curves for mild steel in 1 M HCl containing 0, 10, 50, 100, and 200 ppm of the miconazole nitrate at 30°C. Corrosion current () was found to decrease with increase in inhibitor concentration indicating the increased inhibition efficiency with the increase in the concentration of the inhibitor. In acidic solution the anodic process of corrosion is the passage of metal ions from the solid metal to the solution, and the principal cathodic process is the discharge of hydrogen gas or reduction of oxygen. The inhibitor may affect either of them or both anodic and cathodic process.

Figure 2: Potentiodynamic polarization curves of mild steel in 1 M HCl solution at 30°C containing various concentrations of inhibitor.

The decrease in with increase in inhibitor concentration was associated with shift in the corrosion potential () to more positive value, indicating suppression of anodic reaction. Thus inhibitor acts as anodic inhibitor for mild steel in hydrochloric acid medium. The inhibitor gets adsorbed on the steel surface and the adsorbed inhibitor prevents the metal atoms from participating in the anodic reaction of corrosion. The values associated with electrochemical parameter and calculated inhibition efficiency (I.E%) for mild steel is given in Table 1. The inhibition efficiency is given by [21] where, and are the corrosion currents in the presence and absence of the inhibitor, respectively.

Table 1: Electrochemical parameters of mild steel in 1 M HCl solution at 30°C.

(inhibitor)/ppm
(A)

(V)
βa (V/dec)
βc (V/dec)
I.E (%)

0
28.1
13.2
−0.5105
5.106
7.357
—

10
4.992
2.279
−0.4816
7.108
3.772
82.23

50
3.833
1.75
−0.4872
7.124
4.237
86.35

100
2.048
0.9349
−0.4804
8.751
6.894
92.71

200
1.273
0.5813
−0.4679
8.717
6.996
95.46

Corrosion rate () in mpy (mils penetration per year) is calculated using [22] where is the atomic weight of the metal, is the current density in A/cm², is the number of electrons lost, is the density in g/cm³, and is a corrosion constant depending on the unit of corrosion rate (for mpy, ).

3.2. Electrochemical Impedance Spectroscopic Measurements (EIS)

The impedance spectra (Nyquist plots) of mild steel in 1 M HCl containing 0, 10, 50, 100, and 200 ppm of the miconazole nitrate at 30°C is shown in Figure 3 Nyquist plots contain depressed semicircle with centre under real axis. The size of the semicircle increases with the inhibitor concentration, indicating the charge transfer process as the main controlling factor of the corrosion of mild steel. It is apparent from the plot that the impedance of the inhibited solution has increased with the increase in the concentration of the inhibitor. The experimental result of EIS measurements for the corrosion of mild steel in 1 M HCl in the absence and presence of inhibitor is given in Table 2. As it can be observed from the table, the polarization resistance () value increased with increase in the concentration of the inhibitor whereas values of the capacitance of the interface () starts decreasing, with increase in inhibitor concentration, which is most probably due to the decrease in local dielectric constant and/or increase in thickness of the electrical double layer. This suggests that the inhibitor acts via adsorption at the metal/solution interface [23] and the decrease in the values is caused by the gradual replacement of water molecules by the adsorption of the inhibitor molecules on the electrode surface, which decreases the extent of metal dissolution [24].

Table 2: AC impedance data of mild steel in 1 M HCl solution at 30°C.

(inhibitor)/ppm

I.E (%)

0
7.17
—
318.24

10
41.77
82.83
255.55

50
66
89.13
205.05

100
96.75
92.58
175.74

200
135.6
94.71
169.61

Figure 3: Nyquist plots for mild steel in 1 M HCl solution at 30°C containing various concentrations of inhibitor.

The inhibition efficiency is given by [25] where is polarization resistance without inhibitor, and is polarization resistance with inhibitor.

value is obtained from (4): where, is the frequency at the top of the semicircle (where-Z′′ is maximum).

3.3. Weight Loss Measurements

3.3.1. Effect of Inhibitor Concentration

The weight loss results of mild steel in 1 M HCl in the absence and presence of various concentrations of the inhibitor are summarized in Table 3. The inhibition efficiency was calculated using the following equation: where and are weight loss of mild steel in the absence and presence of the inhibitor, respectively.

Table 3: Corrosion parameters for mild steel in 1 M HCl in the absence and presence of different concentrations of the inhibitor at 30°C by weight loss measurements.

(inhibitor)/ppm
Weight loss (mg cm)
I.E (%)

0
127.52
—

5
36.86
71.09

10
20.66
83.8

50
14.54
88.6

100
7.22
94.34

200
3.67
97.12

500
1.4
98.9

The surface coverage () was calculated from the following equation:

The corrosion rate () in mils penetration per year (mpy) is calculated using the formula [22] where is weight loss in milligrams, is density in grams per cubic centimeter, is area in square inches, and is exposure time in hours.

The inhibition efficiency increased with increase in the concentration of the inhibitor for mild steel in 1 M HCl. Results obtained from polarization, EIS and weight loss measurements are in good agreement with each other.

3.3.2. Effect of Temperature

To elucidate the mechanism of inhibition and to determine the thermodynamic parameters of the corrosion process weight loss measurements were performed at 30, 40, 50, and 60°C. The effect of temperature on the corrosion inhibition of mild steel in the presence of the inhibitor is graphically represented in Figure 4.

Figure 4: Effect of temperature on I.E (%) for mild steel in 1 M HCl in the presence of different concentrations of the inhibitor.

The slight increase in the inhibition efficiency for corrosion of mild steel at higher temperature can be attributed to the occurrence of chemical adsorption of the inhibitor molecules on its surface. Reported drug, miconazole nitrate has better inhibition efficiency than the already reported antifungal drugs [14–16].

3.3.3. Thermodynamic Parameters

The apparent activation energy () of metal corrosion in acid media can be calculated from the Arrhenius equation [26] where is the apparent activation energy for the corrosion of mild steel, is the universal gas constant, is Arrhenius pre-exponential factor, and is the absolute temperature. The values of obtained from the slope of the versus plot (Figure 5) are given in Table 4.

Table 4: Values of activation parameters for mild steel in 1 M HCl in the absence and presence of different concentrations of the inhibitor.

(inhibitor)/ppm
(kJ mol)
(kJ mol)
(J mol)

0
36.72
34.08
−127.57

10
34.86
32.22
−148.76

50
33.25
30.61
−156.95

100
26.21
23.57
−186.19

200
21.29
18.65
−207.88

Figure 5: Arrhenius plot for mild steel in 1 M HCl solution in the absence and presence of different concentrations of the inhibitor.

The relationship between the temperature dependence of inhibition efficiency of an inhibitor and the activation energy found in its presence was given as follows [27].(i)Inhibitors whose inhibition efficiency decreases with temperature increase. The value of activation energy () found is greater than that in the uninhibited solution.(ii)Inhibitors whose inhibition efficiency does not change with temperature variation. The value of activation energy () does not change with the presence or absence of inhibitors.(iii)Inhibitors whose inhibition efficiency increases with temperature increase. The value of activation energy () found is less than that in the uninhibited solution.

The higher value of activation energy () in the presence of inhibitor than in its absence is attributed to its physical adsorption, while its chemisorptions is [28] pronounced in the opposite case [11].

In the present study the lower value of for mild steel in an inhibitor’s presence, compared to that in its absence indicates chemical adsorption. Riggs and Hurd [29] explained that the decrease in activation energy of corrosion at higher levels of inhibition arises from a shift of the net corrosion reaction from that on the uncovered part on the metal surface to the covered one. An alternative form of Arrhenius equation is the transition state equation [26]: where, is Plank’s constant, is Avogadro’s number, is the entropy of activation, and is the enthalpy of activation. A plot of versus gave a straight line (Figure 6) with a slope of () and an intercept of , from which the values of and were calculated and listed in Table 4.

Figure 6: Transition plot for mild steel in 1 M HCl solution in the absence and presence of different concentrations of the inhibitor.

The positive values of for corrosion ofmild steel in the presence and absence of the inhibitor reflect the endothermic nature of metal dissolution process. The decrease in with increase in inhibitor concentration for mild steel corrosion reflected that decrease in mild steel corrosion rate is chiefly decided by the pre-exponential factor [30].

The negative increment in with increase in the concentration of the inhibitor reveals that decrease in randomness takes place on going from reactant to the activated complex [31]. This reflects the formation of an ordered stable film of inhibitor on mild steel surface [32].

3.3.4. Adsorption Isotherms

In order to understand the mechanism of corrosion inhibition, the adsorption behavior of the organic adsorbate on the metal surface has to be known. The degree of surface coverage () for different concentration of the inhibitor () has been evaluated. The data were tested graphically by fitting to various isotherms. A straight line with correlation coefficient nearly equal to 1.0 was obtained on plotting against suggesting adsorption of the compound on the mild steel surface followed Langmuir adsorption isotherm model (Figure 7) at all studied temperatures. According to this isotherm, the surface coverage () is related to inhibitor concentration [33] by where is equilibrium constant of the equilibrium adsorption process. This isotherm assumes that adsorbed molecules occupy only one site and it does not interact with other adsorbed species.

Figure 7: Langmuir adsorption isotherm for mild steel in 1 M HCl solution at 30°C.

The values can be calculated from the intercept lines on the axis. This is related to the standard free energy of adsorption () by the following equation: where is the gas constant and is the absolute temperature. The constant value of 55.5 is the concentration of water in solution in mol/L. The calculated values of and are given in Table 5.

Table 5: Values of thermodynamic parameters for the adsorption of the inhibitor in 1 M HCl on the mild steel at different temperatures.

Temperature (K)
(mol)
(kJ mol)
(kJ mol)
(J mol)

303
12.832
−39.7487
     1.77
     136.96

313
12.954
−41.0852

323
13.019
−42.4113

333
13.758
−43.8771

Generally, the magnitude of around −20 kJ/mol or less negative indicates electrostatic interactions between inhibitor and the charged metal surface (i.e., physisorption). Those around −40 kJ/mol or more negative are indicative of charge sharing or transferring from organic species to the metal surface to form a coordinate type of metal bond (i.e., chemisorptions). In the present work, the calculated values of at 30°C for mild steel is −39 kJ/mol, which indicated that adsorption of the inhibitor on the metal surface involves complex interactions: both physical and chemical process [34–36]. The negative value of indicated spontaneous adsorption of the inhibitor on the metal surface. The slight increase in for mild steel showed increased adsorption with increase in temperature.

The enthalpy of adsorption can be calculated from the rearranged Gibbs-Helmholtz equation: Figure 8 shows the variation of with . The plot gave a straight line with a typographical error of ±1.65%. The slope of straight line, is given in Table 5. The positive sign of indicated the endothermic process of adsorption of inhibitor on mild steel. The entropy of adsorption (Table 5) was calculated using the following thermodynamic equation: The positive value of in the presence of inhibitor is an indication of increase in solvent entropy. It also interpreted with increase of disorders due to more water molecules which can be desorbed from the metal surface by one inhibitor molecule. Therefore, it is revealed that decrease in the enthalpy is the driving force for the adsorption of the inhibitor on the surface of the metal [37–39].

Figure 8: versus plot for mild steel in 1 M HCl solution.

3.4. Mechanism of Corrosion Inhibition

The adsorption of the inhibitor molecule is often a displacement reaction involving removal of adsorbed water molecules from the metal surface, In general, the physisorption involves electrostatic force of attraction between electrically charged surface of metal and charged species in the bulk of this solution. While chemisorptions involve charge sharing or electrons transfer from the inhibitor molecule to the metal surface to form coordinate type of bond.

In HCl medium, the metal surface is negatively charged due to the specifically adsorbed ions on the metal surface. In acidic solution, the nitrogen atom of the imidazole ring of the inhibitor can be protonated easily, due to high electron density on it, leading to positively charged inhibitor species. The adsorption can occur via electrostatic interaction between positively charged inhibitor molecules and negatively charged metal surface [11, 24]. Further, co-ordinate bond may be formed between unshared pairs of unprotonated oxygen atom or nitrogen atom of the inhibitor and vacant d-orbital of mild steel surface. Additionally, inhibitor molecule may be chemically adsorbed due to interaction of electrons of the inhibitor with metal surface [34].

4. Conclusion

(1)Miconazole nitrate is a good inhibitor for the corrosion of mild steel in 1 M HCl and inhibition efficiency was more pronounced with increase in the inhibitor concentration.(2) The results obtained from polarization, impedance techniques, and weight loss measurements are in good agreement. (3)The potentiodynamic polarization curves imply that the corrosion inhibition by miconazole nitrate for mild steel in 1 M HCl is mainly due to the suppression of anodic reaction.(4) The inhibition efficiency of the inhibitor slightly increased with temperature for corrosion of mild steel.(5)The adsorption of inhibitor on the surface of mild steel obeys Langmuir adsorption isotherm.

Acknowledgment

The authors thank Dr. ArthobaNaik and Dr. Basavanna of Kuvempu University for their help and support.

References

M. Zerfaoui, H. Oudda, B. Hammouti, S. Kertit, and M. Benkaddour, “Inhibition of corrosion of iron in citric acid media by aminoacids,” Progress in Organic Coatings, vol. 51, no. 2, pp. 134–138, 2004.

M. K. Awad, “Semiempirical investigation of the inhibition efficiency of thiourea derivatives as corrosion inhibitors,” Journal of Electroanalytical Chemistry, vol. 567, no. 2, pp. 219–225, 2004.

R. Solmaz, G. Kardaş, M. Çulha, B. Yazici, and M. Erbil, “Investigation of adsorption and inhibitive effect of 2-mercaptothiazoline on corrosion of mild steel in hydrochloric acid media,” Electrochimica Acta, vol. 53, no. 20, pp. 5941–5952, 2008.

S. T. Selvi, V. Raman, and N. Rajendran, “Corrosion inhibition of mild steel by benzotriazole derivatives in acidic medium,” Journal of Applied Electrochemistry, vol. 33, no. 12, pp. 1175–1182, 2003.

V. Ramesh Saliyan and A. Vasudeva Adhikari, “Quinolin-5-ylmethylene-3-{[8-(trifluoromethyl)quinolin-4-yl]thio}propanohydrazide as an effective inhibitor of mild steel corrosion in HCl solution,” Corrosion Science, vol. 50, no. 1, pp. 55–61, 2008.

J. M. Bastidas, J. L. Polo, and E. Cano, “Substitutional inhibition mechanism of mild steel hydrochloric acid corrosion by hexylamine and dodecylamine,” Journal of Applied Electrochemistry, vol. 30, no. 10, pp. 1173–1177, 2000.

Jyotsna Shukla and K. S. Pitre, “Corrosion of carbon steel in inhibited acidic medium: a new voltammetric approach,” Bulletin of Electrochemistry, vol. 20, no. 7, pp. 309–313, 2004.

G. Bereket, C. Ögretir, and A. Yurt, “Quantum mechanical calculations on some 4-methyl-5-substituted imidazole derivatives as acidic corrosion inhibitor for zinc,” Journal of Molecular Structure, vol. 571, pp. 139–145, 2001.

D. U. Tianbao, Jiajian Chen, and Dianzhen Cao, “N,N-dipropynoxy methyl amine trimethyl phosphonate as corrosion inhibitor for iron in sulfuric acid,” Journal of Materials Science, vol. 36, no. 16, pp. 3903–3907, 2001.

V. Branzoi, Florentian Golgovici, and Florina Branzoi, “Aluminium corrosion in hydrochloric acid solutions and the effect of some organic inhibitors,” Materials Chemistry and Physics, vol. 78, no. 1, pp. 122–131, 2003.

I. B. Obot, N. O. Obi-Egbedi, and S. A. Umoren, “Antifungal drugs as corrosion inhibitors for aluminium in 0.1 M HCl,” Corrosion Science, vol. 51, no. 8, pp. 1868–1875, 2009.

G. Schmitt, “Application of inhibitors for acid media,” British Corrosion Journal, vol. 19, no. 4, pp. 165–176, 1984.

M. Abdallah, “Antibacterial drugs as corrosion inhibitors for corrosion of aluminium in hydrochloric solution,” Corrosion Science, vol. 46, no. 8, pp. 1981–1996, 2004.

S. A. Odoemelam, E. C. Ogoko, B. I. Ita, and N. O. Eddy, “Adsorption and inhibitive properties of clarithromycin for the corrosion of Zn in 0. 01 to 0. 05 M H₂SO₄,” Portugaliae Electrochimica Acta, vol. 27, no. 6, pp. 713–724, 2009.

R. Solmaz, G. Kardaš, B. Yažiči, and M. Erbil, “Inhibition effect of rhodanine for corrosion of mild steel in hydrochloric acid solution,” Protection of Metals, vol. 41, no. 6, pp. 581–585, 2005.

A. S. Fouda, H. A. Mostafa, and H. M. El-Abbasy, “Antibacterial drugs as inhibitors for the corrosion of stainless steel type 304 in HCl solution,” Journal of Applied Electrochemistry, vol. 40, no. 1, pp. 163–173, 2010.

F. Delia Morris and L. Denis Sugrue, “Miconazole nitrate compared with chlordantoin in the treatment of vaginal candidiasis,” British Journal of Venereal Diseases, vol. 51, no. 2, pp. 123–124, 1975.

L. Susan and S. L. Zunt, “Oral candidiasis: diagnosis and treatment,” The Journal of Practical Hygiene, vol. 9, no. 5, pp. 31–36, 2000.

U. Edelmann and J. Wiese, “Candida vaginitis treated with a single dose of miconazole nitrate (Brentan®-vaginal capsules),” Ugeskrift for Laeger, vol. 142, no. 28, pp. 1812–1813, 1980.

L. Fang, Y. Zhang, and L. Tian, “Global optimization for alignment of generalized shapes,” China Tropical Medicine, vol. 9, p. 1998, 2009.

K. C. Emregül, A. A. Akay, and O. Atakol, “The corrosion inhibition of steel with Schiff base compounds in 2 M HCl,” Materials Chemistry and Physics, vol. 93, no. 2-3, pp. 325–329, 2005.

M. G. Fontana, Corrosion Engineering, Mc Graw Hill, New York, NY, USA, 3rd edition, 1991.

K. F. Khaled, “The inhibition of benzimidazole derivatives on corrosion of iron in 1 M HCl solutions,” Electro—Chimica Acta, vol. 48, no. 17, pp. 2493–2503, 2003.

J. Aljourani, K. Raeissi, and M. A. Golozar, “Benzimidazole and its derivatives as corrosion inhibitors for mild steel in 1M HCl solution,” Corrosion Science, vol. 51, no. 8, pp. 1836–1843, 2009.

J. Cruz, R. Martínez, J. Genesca, and E. García-Ochoa, “Experimental and theoretical study of 1-(2-ethylamino)-2-methylimidazoline as an inhibitor of carbon steel corrosion in acid media,” Journal of Electroanalytical Chemistry, vol. 566, no. 1, pp. 111–121, 2004.

Q. Zhang and Y. Hua, “Corrosion inhibition of aluminum in hydrochloric acid solution by alkylimidazolium ionic liquids,” Materials Chemistry and Physics, vol. 119, no. 1–2, pp. 57–64, 2010.

I. Dehri and M. Özcan, “The effect of temperature on the corrosion of mild steel in acidic media in the presence of some sulphur-containing organic compounds,” Materials Chemistry and Physics, vol. 98, no. 2–3, pp. 316–323, 2006.

T. Szauer and A. Brandt, “On the role of fatty acid in adsorption and corrosion inhibition of iron by amine-fatty acid salts in acidic solution,” Electrochimica Acta, vol. 26, no. 9, pp. 1219–1224, 1981.

O. L. Riggs Jr. and R. M. Hurd, “Temperature coefficient of corrosion inhibition,” Corrosion, vol. 23, no. 8, p. 252, 1967.

M. Bouklah, B. Hammouti, M. Lagrenée, and F. Bentiss, “Thermodynamic properties of 2,5-bis(4-methoxyphenyl)-1,3,4-oxadiazole as a corrosion inhibitor for mild steel in normal sulfuric acid medium,” Corrosion Science, vol. 48, no. 9, pp. 2831–2842, 2006.

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.

F. Bentiss, M. Lebrini, and M. Lagrenée, “Thermodynamic characterization of metal dissolution and inhibitor adsorption processes in mild steel/2,5-bis(n-thienyl)-1,3,4-thiadiazoles/ hydrochloric acid system,” Corrosion Science, vol. 47, no. 12, pp. 2915–2931, 2005.

X. H. Li, S. D. Deng, G. N. Mu, H. Fu, and F. Z. Yang, “Inhibition effect of nonionic surfactant on the corrosion of cold rolled steel in hydrochloric acid,” Corrosion Science, vol. 50, no. 2, pp. 420–430, 2008.

Ashish Kumar Singh and M. A. Quraishi, “Effect of Cefazolin on the corrosion of mild steel in HCl solution,” Corrosion Science, vol. 52, no. 1, pp. 152–160, 2010.

M. Bouklah, N. Benchat, B. Hammouti, A. Aouniti, and S. Kertit, “Thermodynamic characterisation of steel corrosion and inhibitor adsorption of pyridazine compounds in 0.5 M HSO,” Materials Letters, vol. 60, no. 15, pp. 1901–1905, 2006.

E. Geler and D. S. Azambuja, “Corrosion inhibition of copper in chloride solutions by pyrazole,” Corrosion Science, vol. 42, no. 4, pp. 631–643, 2000.

Ashish Kumar Singh and M. A. Quraishi, “The effect of some bis-thiadiazole derivatives on the corrosion of mild steel in hydrochloric acid,” Corrosion Science, vol. 52, no. 4, pp. 1373–1385, 2010.

Gulsen Avci, “Corrosion inhibition of indole-3-acetic acid on mild steel in 0.5 M HCl,” Colloids and Surfaces, vol. 317, no. 1–3, pp. 730–736, 2008.

Xianghong Li, Shudan Deng, Hui Fu, and Guannan Mu, “Inhibition effect of 6-benzylaminopurine on the corrosion of cold rolled steel in HSO solution,” Corrosion Science, vol. 51, no. 3, pp. 620–634, 2009.