S.Karthikeyan, P.A.Jeeva, M.Paramasivam
Keywords: Corrosion inhibitor, Sulfalene, hydrogen permeation
Abstract:
The influence of Sulfalene (SFL) on corrosion and hydrogen permeation through Stainless steel 304 in 5% NaCl has been studied using weight loss measurements and various electrochemical techniques. The inhibitor is found to be more effective in retarding the metal corrosion saline medium. Potentiodynamic polarization studies clearly indicate that SFL behaves as a mixed inhibitor. Hydrogen permeation studies and AC impedance measurements also proved an excellent performance of the compound in 5% NaCl. The adsorption of this compound on the mild steel surface obeys Temkin’s adsorption isotherm which is further validated by Quantum chemical calculations.
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ISSN 1466-8858 Volume 17, Preprint 5 submitted 16 January 2014 © 2014 University of Manchester and the authors. This is a preprint of a paper that has been submitted for publication in the Journal of Corrosion Science and Engineering. It will be reviewed and, subject to the reviewers" comments, be published online at http://www.jcse.org in due course. Until such time as it has been fully published it should not normally be referenced in published work. 1 The influence of Sulfalene drug (SFL) on the Corrosion and hydrogen permeation through Stainless steel 304 in 5% NaCl-Part I S.Karthikeyan 1*, P.A.Jeeva 2 , M.Paramasivam 3 1 Surface Engineering Research lab, CNBT , VIT University, Vellore -632014,India 2 Design Division, School of Mechanical and Building Sciences, VIT University, Vellore - 632014, India 3 EPS Division, CSIR-CECRI, Karaikudi-630006, India Abstract The influence of Sulfalene (SFL) on corrosion and hydrogen permeation through Stainless steel 304 in 5% NaCl has been studied using weight loss measurements and various electrochemical techniques. The inhibitor is found to be more effective in retarding the metal corrosion saline medium. Potentiodynamic polarization studies clearly indicate that SFL behaves as a mixed inhibitor. Hydrogen permeation studies and AC impedance measurements also proved an excellent performance of the compound in 5% NaCl. The adsorption of this compound on the mild steel surface obeys Temkin's adsorption isotherm which is further validated by Quantum chemical calculations. Keywords: Corrosion inhibitor, Sulfalene, hydrogen permeation 1* corresponding author (skarthikeyanphd@yahoo.co.in) ISSN 1466-8858 Volume 17, Preprint 5 submitted 16 January 2014 © 2014 University of Manchester and the authors. This is a preprint of a paper that has been submitted for publication in the Journal of Corrosion Science and Engineering. It will be reviewed and, subject to the reviewers" comments, be published online at http://www.jcse.org in due course. Until such time as it has been fully published it should not normally be referenced in published work. 21. Introduction Antibiotics and allied drugs have been reported in recent years as corrosion inhibitors because of their less toxicity [1-3]. Organic compounds containing sulphur, nitrogen and oxygen atoms are capable of retarding metallic corrosion. While extensive investigations have been carried out on inhibitor properties of antifungal drugs , due attention has not yet been paid to a systematic study on Sulfalene as potential corrosion inhibitors for stainless steel alloys in high corrosive medium, i.e 5% NaCl. However, very few reports are available using Sulfalene as corrosion inhibitors for aluminium in HCl medium [4]. Most of the effective organic inhibitors have hetero atoms such as O, N, S containing multiple bonds in their molecules through which they can adsorb on the metal surface [5-9]. The corrosion inhibiting property of these compounds is attributed to their molecular structure. The lone pair of electrons on nitrogen of amino group attached with benzene ring of SFL , lone pair of electrons of oxygen atoms of sulphoxide group, nitrogen atom , delocalization of electrons of benzene ring and imidazoline groups of the present drug establish the adsorption of the compound on SS 304 surface. All the above studies expose one common observation that Sulfalene can be regarded as excellent corrosion inhibitors. But studies on the influence of Sulfalene on hydrogen permeation through steel substrate during pickling are very scarce. It belongs to the class of imidazole and sulpho amido derivatives for topical use and utilized in the treatment of fungal infection. A good inhibitor should have the following two important requisites: (1) it should have very good inhibition efficiency and (2) it should bring down the hydrogen permeation ISSN 1466-8858 Volume 17, Preprint 5 submitted 16 January 2014 © 2014 University of Manchester and the authors. This is a preprint of a paper that has been submitted for publication in the Journal of Corrosion Science and Engineering. It will be reviewed and, subject to the reviewers" comments, be published online at http://www.jcse.org in due course. Until such time as it has been fully published it should not normally be referenced in published work. 3current to a considerable extent. Some organic compounds offer very high values of inhibition efficiency, but they have a insignificant effect in plummeting the hydrogen permeation current and vice versa. Compounds which come under this class produce hydrogen embrittlement in a later stage by the combination of permeated atomic hydrogen. This delayed failure creates cracking, pitting, breakage, etc., on the metal surface. 2. Experimental Stainless steel 304 specimens of compositions, C= 0.08% , Si = 0%, Ni = 8%, Cr = 18% and Fe remainder, and of size 4 x 1 x 0.020 cm were used for weight loss and hydrogen permeation studies. A mild steel cylindrical rod of the same composition as above and embedded in araldite resin with an exposed area of 0.283 cm 2 was used for potentio polarisation and AC impedance measurements. The inhibitor was preliminarily screened by a weight loss method described earlier. [9] Both cathodic and anodic polarisation curves were recorded potentiodynamically (1 mA s -1 ) using corrosion measurement system BAS Model: 100A computerized electrochemical analyzer (made in West Lafayette, Indiana) and PL-10 digital plotter (DMP-40 series, Houston Instruments Division). A platinum foil, Hg/Hg 2Cl2/KCl (satd) were used as auxiliary and reference electrodes, respectively. The hydrogen permeation study was carried out using an adaptation of the modified Devanathan and Stachurski's two compartment cell, as described earlier [4]. Double layer capacitance (Cdl) and charge transfer resistance values (R,) were obtained using AC impedance measurements as described in an earlier publication." The surfaces of ISSN 1466-8858 Volume 17, Preprint 5 submitted 16 January 2014 © 2014 University of Manchester and the authors. This is a preprint of a paper that has been submitted for publication in the Journal of Corrosion Science and Engineering. It will be reviewed and, subject to the reviewers" comments, be published online at http://www.jcse.org in due course. Until such time as it has been fully published it should not normally be referenced in published work. 4corroded and corrosion inhibited mild steel specimens were examined by diffuse reflectance studies in the region 200- 700 nm using U-3400 spectrometer (UV-VIS- NIR Spectrometer, Hitachi, Japan). 3. RESULTS AND DISCUSSION 3.1 Weight loss and Gasometric measurements Table 1 gives the values of inhibition efficiency for different concentrations of Sulfalene for the corrosion of SS 304 in 5% NaCl obtained from weight loss and gasometric measurements. It is found that the compound inhibits the corrosion of stainless steel in saline medium effectively. The structure of the compound is given in Figure 1. H 2 NS O O NH NN O Figure 1. Structure of Sulfalene The inhibition of corrosion of brought about by Sulfalene can be due to the following interactions: 1.The interaction between the lone pairs of electrons of the nitrogen atoms of the imidazole ring and the positively charged metal surface [10]. ISSN 1466-8858 Volume 17, Preprint 5 submitted 16 January 2014 © 2014 University of Manchester and the authors. This is a preprint of a paper that has been submitted for publication in the Journal of Corrosion Science and Engineering. It will be reviewed and, subject to the reviewers" comments, be published online at http://www.jcse.org in due course. Until such time as it has been fully published it should not normally be referenced in published work. 52.The interactions between delocalized electrons of the benzene groups and the positively charged metal surface [11]. It is found that there is very good conformity between the values of inhibition efficiency obtained by weight loss and gasometric methods. 3.2 Potentiodynamic polarization studies Table 2 indicates values of corrosion kinetic parameters such as Tafel slopes ( b a and bc ), corrosion current (I corr ) , corrosion potential (E corr ) and inhibition efficiency obtained from potentiodynamic polarization plots for SS 304 in NaCl in the presence of different concentrations of inhibitor. It can be visualized from this table that values of Tafel slopes and I corr are very much similar to those reported earlier [12-13]. Further it is confirmed that enhancing the concentrations of Sulfalene alters the values of both b a and bc in irregular fashion justifying that the inhibition of corrosion of SS 304 in saline medium is under mixed control. Values of E corr is shifted to less negative values in the presence of different concentrations of SFL. This can be attributed to the formation of strongly adherent adsorbed film on the metal surface. The presence of increasing concentrations of Sulfalene retards I corr values in 5% NaCl. It can also be seen that most of the values of inhibition efficiency obtained by weight loss measurements and potentiodynamic polarization studies agree very well. ISSN 1466-8858 Volume 17, Preprint 5 submitted 16 January 2014 © 2014 University of Manchester and the authors. This is a preprint of a paper that has been submitted for publication in the Journal of Corrosion Science and Engineering. It will be reviewed and, subject to the reviewers" comments, be published online at http://www.jcse.org in due course. Until such time as it has been fully published it should not normally be referenced in published work. 6 3.3 Hydrogen permeation measurements Hydrogen permeation measurements results for the corrosion of SS 304 in the presence and absence of the inhibitor are presented in Table 3. Hydrogen permeation current for stainless steel in 5% NaCl is more, because of the aggressive nature of chloride ions. It can be seen from the table that the presence of Sulfalene in saline medium retards the entry of hydrogen gas and does not influence the ingress of hydrogen gas into SS 304. The reduction in permeation current can be ascribed to the effective adsorption of the compound on the mild steel surface [12- 16]. It can be found from the table that the decrement of permeation current is more, if the concentration of Sulfalene is more. 3.4 Impedance studies Values of charge transfer resistance (Rt )and double layer capacitance (Cdl) derived from Nyquist graphs are shown in table 4. It can be seen in table that the values of R t has begun to increase with enhancement of SFL concentrations in 5% NaCl. Values of double layer capacitance are establishing that steel dissolution is high in 5% NaCl .It is found that values of Cdl are decreased by increasing concentrations of Sulfalene in electrolyte. This could be due to the increased adsorption of the SFL molecule on the surface of SS 304 as the concentration of inhibitor increases. A plot of surface coverage (ø ) versus log C gave a straight line illustrating that the adsorption of SFL on SS 304 surface from 5% NaCl follows Temkin's adsorption isotherm. This is major support to corrosion inhibition by this compound, as a result of its adsorption on the metal surface. ISSN 1466-8858 Volume 17, Preprint 5 submitted 16 January 2014 © 2014 University of Manchester and the authors. This is a preprint of a paper that has been submitted for publication in the Journal of Corrosion Science and Engineering. It will be reviewed and, subject to the reviewers" comments, be published online at http://www.jcse.org in due course. Until such time as it has been fully published it should not normally be referenced in published work. 7 3.5 Quantum chemical studies: Figure 2. Highly Occupied MO's of inhibitors Figure 3. Lowest unoccupied MO's of inhibitors The computed quantum chemical indices such as energy of highest occupied molecular orbital (E HOMO), energy of lowest unoccupied molecular orbital (ELUMO), LUMO- HOMO, energy gap (E), dipole moment (µ), are summarized in Table 5. From figures 2 and 3, it can be observed that HOMO and LUMO energy orbital's ISSN 1466-8858 Volume 17, Preprint 5 submitted 16 January 2014 © 2014 University of Manchester and the authors. This is a preprint of a paper that has been submitted for publication in the Journal of Corrosion Science and Engineering. It will be reviewed and, subject to the reviewers" comments, be published online at http://www.jcse.org in due course. Until such time as it has been fully published it should not normally be referenced in published work. 8were strongly distributed on benzene groups and and imidazole moiety for HOMO structure nitrogen and almost nil, on aniline moiety in the case of HOMO and LUMO establishing that the imidazoline and imino moieties contain good adsorption centres [17-20] and this is in agreement with publications of molecular orbital studies confronting that electrons and N atoms are liable for inhibition activity 20 . According to karthikeyan et al. [21], when a molecule possess similar frontier orbitals, its inhibition effectiveness can be allied to the energy levels of HOMO and LUMO and the distinction between them. It has been widely investigated that, higher the value of E HOMO, better will be the adsorption of an inhibitor by virtue of releasing electrons to vacant d orbital of metal atom and higher is the inhibition efficiency. Also, lower E LUMO values, associated with the acceptance of electrons from metal atom to make feedback bonds. Hence the gap between HOMO-LUMO energy levels of molecules was calculated as a vital data. Smaller value of E of an inhibitor, signify the effective inhibition efficiency of organic compound. It has been reported that, large values of dipole moment will considerably enhance the corrosion inhibition[22-24]. ISSN 1466-8858 Volume 17, Preprint 5 submitted 16 January 2014 © 2014 University of Manchester and the authors. This is a preprint of a paper that has been submitted for publication in the Journal of Corrosion Science and Engineering. It will be reviewed and, subject to the reviewers" comments, be published online at http://www.jcse.org in due course. Until such time as it has been fully published it should not normally be referenced in published work. 9 4. Conclusions 1. Sulfalene inhibits the corrosion of SS 304 in 5% NaCl effectively. 2. The inhibition of corrosion of stainless steel in salt water, by the inhibitor is under mixed control. 3. The presence of inhibitor molecule in salt water is found to reduce the extent of entry of hydrogen through steel surface. 4. R t and Cdl values studied from impedance measurements confirm the improved performance of the compound. 5. The adsorption of the inhibitor on SS 304 surface follows Temkin's adsorption isotherm which is further validated from quantum chemical calculations. References: [1] Rhodanine azosulpha drugs as corrosion inhibitors for corrosion of 304 stainless steel in hydrochloric acid solution, M. Abdallah, Corros. Sci, 44, pp728, 2002. [2] Antifungal drugs as corrosion inhibitors for aluminium in 0. HCl, I.B. Obot, N.O. Obi-Egbedi, S.A. Umoren, Int. J. Electrochem. Sci, Vol. 4, 2009. [3] Torsemide and Furosemide as Green Inhibitors for the Corrosion of Mild Steel in Hydrochloric Acid Medium, S. Harikumar and S. Karthikeyan, Industrial and Engineering Chemistry Research, 52(22), pp. 7457-7469,2013. ISSN 1466-8858 Volume 17, Preprint 5 submitted 16 January 2014 © 2014 University of Manchester and the authors. This is a preprint of a paper that has been submitted for publication in the Journal of Corrosion Science and Engineering. It will be reviewed and, subject to the reviewers" comments, be published online at http://www.jcse.org in due course. Until such time as it has been fully published it should not normally be referenced in published work. 10[4] Adsorption characteristics and corrosion inhibitive properties of clotrimazole for Aluminium corrosion in hydrochloric acid, I. Obot, N.Umoren, Int. J. Electrochem. Sci, Vol. 4, pp. 863-877, 2009. [5] Inhibition of mild steel corrosion in hydrochloric acid solution by cloxacillin drug, S. Harikumar and S. Karthikeyan, Journal of Materials and Environmental Studies, Vol.5, pp. 925-934, 2012. [6] Influence of some thiazole derivatives on corrosion of mild steel in hydrochloric acid, M.A. Quraishi, M.A.W. Khan, M. Ajmal, Anti-Corros. Methods Mater, 43, 5, 1996. [7] The inhibitive action of cyclohexyl thiourea on corrosion and hydrogen permeation through mild steel in acidic solutions, S. Karthikeyan, S.Harikumar, G. Venkatachalam, S.Narayanan, R. Venckatesh, International Journal of ChemTech Research, 4(3), pp. 1065-1071, 2012. [8] Electrochemical studies of two corrosion inhibitors for iron in HCl, Al-Andis, N.Khamis, E. Al-Mayouf, H. Aboul b Enicm, Corros. Prev. Cont rol, 42, 13,1995. [9] L-Methionine methyl ester hydrochloride as corrosion inhibitor of iron in 1 M HCl, B. Hamm outi, M. Aouniti, M. Taleb, M. Bri ghli, S. Kertit, Corrosion, b,441, 1995. [10] Influence of anions on corrosion inhibition and hydrogen permeation through mild steel in acidic solutions in the presence of p-tolyl thiourea, K. Madhavan, S. Karthikeyan, S.V.K. Iyer, Ind. J.Chem. Tech, 9, pp68, 2002. [11] The Structure of the Electrical Double Layer at the Metal Solution Interface, M.A. Devanathan, B. Til ak, Chem.Revs, 65, pp. 635, 1965. ISSN 1466-8858 Volume 17, Preprint 5 submitted 16 January 2014 © 2014 University of Manchester and the authors. This is a preprint of a paper that has been submitted for publication in the Journal of Corrosion Science and Engineering. It will be reviewed and, subject to the reviewers" comments, be published online at http://www.jcse.org in due course. Until such time as it has been fully published it should not normally be referenced in published work. 11[12] Surface coordination chemistry of monometallic and bimetallic eletrocatalysts, Soriaga, Chem.Revs, 90, pp77, 1990. [13] The inhibition of sulphuric acid corrosion of 410 stainless steel by thioureas, Reeta Agarwal, T.K.G. Namboodri, Corros.Sci, 30, pp37, 1990. [14] Mechanism of corrosion and its inhibition, K. Madhavan, PhD Thesis, Alagappa University, India, June 1996. [15] W.Waiter Voss, J.Chemistry of Amides, Zabersky Edition, Interscience, Newyork, 187, 1997. [16] A.K. Lahiri, N.G. Banerjee, NML. Tech. Journal, 5, pp33, 1963. [17] Gu Hough, Zhou Zhongbai, Tao Yingachu , Yao Luaw, Wahan Dauxe Xuebao, Ziran Kexuebaw, 2, pp57, 1982. [18] G. Trabanelli and Zucchui F.Revon, Corrosion and coatings, 1, pp47, 1973. [19] The use of Quantum chemical methods in corrosion inhibitor studies, G. Gece, Corrosion Science, pp.2981-2992, 2008. [20] Inhibition Effect of Amoxicillin drug on the Corrosion of Mild Steel in 1N Hydrochloric acid Solution, S. Hari Kumar, S. Karthikeyan, S.Narayanan and K.N.Srinivasan, International Journal of ChemTech Research, 4(3), pp. 1077- 1084, 2012. [21] Corrosion inhibition of mild steel in 1M H2So4 by Ampicillin as an inhibitor, S. Hari Kumar, S. Karthikeyan, P.A. Jeeva, Journal of Corrosion Science and Engineering, Vol.16, 2013. ISSN 1466-8858 Volume 17, Preprint 5 submitted 16 January 2014 © 2014 University of Manchester and the authors. This is a preprint of a paper that has been submitted for publication in the Journal of Corrosion Science and Engineering. It will be reviewed and, subject to the reviewers" comments, be published online at http://www.jcse.org in due course. Until such time as it has been fully published it should not normally be referenced in published work. 12[22] The retardation of dissolution of Al-Sic composites in acidic medium -A green approach, V. Umasankar, S. Karthikeyan, M. Anthony Xavier, Journal of Corrosion Science and Engineering, 16, pp47, 2013. [23] Ethane-2- thioamido-4-amino-N-(5-methylisoxazol-3-yl)-benzene sulfonamide: A novel inhibitor for the corrosion of mild steel in 1N HCl , S. Karthikeyan, N. Arivazhagan, S. Narayanan, Journal of Corrosion Science &Engineering, Vol.16, 2013. [24] Performance characteristics of 1, 3-diorthotolyl thiourea on the corrosion of mild steel in 5% NaCl, S. Karthikeyan, N. Arivazhagan, D. Ramkumar, S. Narayanan, Journal of Corrosion Science &Engineering, Vol.16, 2013. Table 1. Values of inhibition efficiency for the corrosion of stainless steel 304 in 5% NaCl in the presence of different concentrations of Sulfalene obtained from weight loss and gasometric measurements. Concentration of Inhibitor (mM) 5% NaCl (Inhibition efficiency) Weight loss Studies Gasometric measurements 20 40 60 80 47 60 72 24.2 46.8 60.2 71.9 24.1 ISSN 1466-8858 Volume 17, Preprint 5 submitted 16 January 2014 © 2014 University of Manchester and the authors. This is a preprint of a paper that has been submitted for publication in the Journal of Corrosion Science and Engineering. It will be reviewed and, subject to the reviewers" comments, be published online at http://www.jcse.org in due course. Until such time as it has been fully published it should not normally be referenced in published work. 13Table 2. Corrosion kinetic parameters of SS 304 in 2N HCl in the presence of different concentrations of Sulfalene obtained from potentiodynamic polarization studies. Concentration of Inhibitor (mM) E corr (mV) Tafel slopes in mV in dec -1 I corr A cm -2 Inhibition efficiency (%) b a bc Blank -320 87 135 19.42 --- 20 -295 68.2 126 10.26 47 40 -292 65.5 119.8 7.8 60.2 60 -280 67 124.5 6.7 72 Table 3. Values of permeation current for the corrosion of stainless steel in 5%NaCl in the presence of different concentrations of Sulfalene . Concentration of Inhibitor (mM) 5% NaCl Blank 20 40 60 20.5 18.3 10.5 7.2 ISSN 1466-8858 Volume 17, Preprint 5 submitted 16 January 2014 © 2014 University of Manchester and the authors. This is a preprint of a paper that has been submitted for publication in the Journal of Corrosion Science and Engineering. It will be reviewed and, subject to the reviewers" comments, be published online at http://www.jcse.org in due course. Until such time as it has been fully published it should not normally be referenced in published work. 14Table 4.Impedance parameters for the corrosion of Stainless steel 304 in NaCl in the presence of different concentrations of Sulfalene . Concentration of Inhibitor (mM) 5% NaCl Charge Transfer resistance (R t) Ohm.cm 2 Double layer capacitance (C dl) µF.cm -2 Blank 20 40 60 3.4 5.4 6.28 7.63 5.9 2.68 3.2 4.1 Table 5: Quantum chemical parameters for Sulfalene Compound LUMO (eV) HOMO (eV) E (Cal.Mol -1 )Dipole moment (Debye) Sulfalene -1.953 -8.343 6.39 5.1