Research Journal of Chemical Sciences ______________________________________________ ISSN 2231-606X Vol. 2(6), 72-81, June (2012) Res.J.Chem.Sci. International Science Congress Association 72 Influence of Melonic acid on the Corrosion Inhibition of Sodium Metavanadate in Chloride MediumSribharathy V.1* and Susai RajendranCorrosion Research Centre, Department of Chemistry, GTN Arts College, Dindigul-624005, Tamil Nadu, INDIA Department of Chemistry, RVS School of Engineering and Technology, Dindugul-624005, Tamil Nadu, INDIAAvailable online at: www.isca.in (Received 21st August 2011, revised 2nd February 2012, accepted 23rd March 2012)Abstract The inhibition efficiency (SMV) – melonic acid system is controlling corrosion of carbon steel in an aqueous solution containing 60 ppm of Cl- has been evaluated by weight loss method.250 ppm of SMV has 56% of IE. Addition of melonic acid to SMV improves the inhibition efficiency of the system. Formulation consisting of 250 ppm of SMV and 250 ppm of melonic acid has 96% IE. Synergistic effects exist between SMV and melonic acid, if the synergism parameters are greater than 1. Mechanistic aspects of corrosion inhibition have been studied by electro chemical studies like polarization and electro chemical impedance spectroscopy. FTIR spectra reveals that the protective film consists of Fe2+ - SMV complex and Fe2+ - melonic acid complex, the protective film has been analyzed by fluorescence spectra, SEM and AFM . Keywords: Carbon steel, corrosion inhibition, fluorescence, synergism parameter, SEM. Introduction Vanadium –based oxyanions, also referred to as vanadate, have been investigated as corrosion inhibitors for Al alloy. However they have not gained much attention probably due to the relatively large solubility of vanadium oxides in aqueous solution1-4. Smith et al explored the release kinetics and protection performance of vanadate –based pigment in epoxy coated MA2014-T6 panel. A later investigation by cook et al screened and compared several inhibitors including vanadates, molybdates, and ion of rare earth elements like Ce, Y, and La. The author analyzed the behaviour of aqueous solutions containing vanadium oxoanions and concluded that metavanadate, ie., vanadate oligomers including V1, V2, V4 and V5 co-ordination are not potent inhibitors of oxygen reduction reaction (ORR) but significally lower the anodic dissolution kinetics. Recently chamber et al studied the synergism of several binary and ternary mixture including vanadate, phosphate, molybdate and rare earth elements. The author concluded that the maximum synergistic effect occurred for vanadate-phosphate solution in ratio 50:50. The co-ordination chemistry of vanadium oxoanions in aqueous solutions is rather complex. It involves several protonation/deprotonation reactions, as well as polymerization to form oligomers of varied depending upon pH and concentration8-12. pH values between 6 and 9 leads to formation of colourless (or) yellow metavanadate [V3O93-] [13-16] this suggest that vanadates are inhibitors of corrosion, and it seems likely the inhibition depends on speciation. The objective of this work: Clear metavanadate solutions containing monovanadate exhibited strong inhibition of the oxygen reduction reaction, to a level similar to chromate. At a fixed pH, increased NaVO3 concentration in clear metavanadate solution increased inhibition efficiency. Material and Methods Preparation of extract: Sodium metavanadate was prepared by dissolving 1g of SMV in double distilled water and making up to 100 ml. This solution was used as a corrosion inhibitor in the present study. Preparation of Specimens: Carbon steel specimens (0.0267% S, 0.06% P, 0.4% Mn, 0.1% C and the rest iron) of dimensions 1.0 cm x 4.0 cm x 0.2 cm were polished to a mirror finish and degreased with trichloroethylene. Weight loss Method: Carbon steel specimens in triplicate were immersed in 100 ml of the solutions containing various concentrations of the inhibitor (sodium metavanadate and melonic acid solution) for three day. The weight of the specimens before and after immersion were determined using Shimadzu balance, model AY 62. The corrosion products were cleansed with Clarke’s solution16. The inhibition efficiency (I.E.) was then calculated using the equation IE = 100 [1-(W2/W1)] % (1) Where W1 = Corrosion rate in the absence of the inhibitor, W2 = Corrosion rate in the presence of the inhibitor Surface Examination: The carbon steel specimens were immersed in various test solutions for a period of one day, taken Research Journal of Chemical Sciences __________________________________________________________ ISSN 2231-606X Vol. 2(6), 72-81, June (2012) Res.J.Chem.SciInternational Science Congress Association 73 out and dried. The nature of the film formed on the surface of metal specimens was analyzed by FTIR spectroscopic study. FTIR Spectra: FTIR spectra were recorded in a Perkin – Elmer 1600 spectrophotometer. The film was carefully removed, mixed thoroughly with KBr made in to pellets and FTIR spectra were recorded. Scanning Electron Microscopic studies: The carbon steel immersed in blank and in the inhibitor solution for a period of one day was removed, rinsed with double distilled water, dried and observed in a scanning electron microscope to examine the surface morphology measurements of the carbon steel were examined using JOEL 6390 model computer controlled scanning electron microscope. Atomic Force Microscopy characterization (AFM): The carbon steel immersed in blank and in the inhibitor solution for a period of one day was removed, rinsed with double distilled water, dried and subjected to the surface examination. The surface morphology measurements of the mild steel surface were carried out by atomic force microscopy (AFM) using veeco innova. Potentiodynamic Polarization: Polarization studies were carried out in an H and CH Electrochemical Work station Impedance Analyzer Model CHI 660A. A three electrode cell assembly was used. The working electrode was carbon steel. A saturated calomel electrode (SCE) was used as the reference electrode and a rectangular platinum foil was used as the counter electrode. AC Impedance Measurements: The instrument used for polarization was used for AC impedance study also. The cell set up was the same as that used for polarization measurements. The real part and imaginary part of the cell impedance were measured in ohms at various frequencies. The values of charge transfer resistance, Rct, and the double layer capacitance, Cdl were calculated. Synergism parameter (S: Synergism parameter is indication of synergistic effect existing between the inhibitors17 value is found to be greater than 1 suggesting that the synergistic effect between the inhibitors. S = I –I1+2 (2) ----------- I –I’1+2 1 = Surface coverage (1) of inhibitor SMV, I = Surface coverage of inhibitor (2) Melonic acid, I’1+2 = Combined surface coverage of inhibitor SMV and MA Analysis of Variance: F-test was carried out to investigate whether synergistic effect existing between inhibitor system is stastically significant18. If F-value is above 5.32 for 1,8 degree of freedom, it was proved to be stastically significant. If the value is below 5.32 for 1, 8 degree of freedom, it was stastically insignificant at 0.05 level of significance confirmed. Results and DiscussionWeight loss study: Evaluation of improvement of IE smv with melonic acid: The inhibition efficiency (IE) of sodium metavanadate (smv) in controlling the corrosion of carbon steel immersed in aqueous solution containing 60 ppm of Cl for a period of three days is given in table 1. It is seen from the data that SMV alone shows some IE; where as melonic acid shows some IE. When SMV is combined with melonic acid ions. For example 250ppm of SMV has only 56% and 250ppm of melonic acid has 85% IE interestingly their combination shows 96% IE This suggests a synergistic effect existing between the binary inhibitor formulation SMV and melonic acid ions. Synernism parameter: The value of synergism parameters are shown in table 2. The value of S is greater than one, suggesting synergistic effect. SI approaches 1 when no interaction exists between the inhibitor compounds. When SI�1, this points to synergistic effect. In the case of SI1, the negative interaction of inhibitor prevails (i.e., corrosion rate increases). Analysis of variance (ANOVA): F-test is used if the synergistic effect exist between inhibitors is statistically significant. The results are given in table 3. Influence of various concentration of melonic acid (50,100,150, 200 and 250ppm) on the Inhibition efficiency of SMV (250ppm) is shown in the table 3. The calculated F-value is 14.8. It is statistically significant, since it is greater than the critical value (5.32) for 1, 8 degree of freedom of 0.05 level of significance. Hence it is concluded that the influence of 250ppm of SMV to the various concentration of melonic acid shows statistically significant. Effect of Sodiumdodecylsulphate (SDS) on the inhibition efficiency of SMV-MA system: The influence of various concentration of SDS on the IE of the SMV-MA system is shown in table 4. It is observed that the IE of SMV-MA with 150ppm of SDS system was 98%. It is interesting to note that the sodium metavanadate - MA system has some biocidal efficiency (BE) in table 5. The BE increases from 67 to 98. When 150ppm of SDS is added 250ppm, 100% BE is noted. The formulation consisting of 250ppm of SMV, 250ppm of MA and 150 ppm of SDS has 100% BE and 98% of corrosion inhibition efficiency. This formulation may find application, if the investigation is carried out at high temperature and under flow condition. FTIR spectra: The FTIR spectrum of pure SMV is shown in Fig 1a VO stretching frequency appears at 1385 cm-1. The FTIR spectrum of pure melonic acid is shown in Fig 1b. The -C=O stretching frequency appeared at 1719 cm-1. –OH stretching frequency appeared at 3407 cm-1. –CH stretching frequency appeared at 2976 cm-1. The FTIR spectrum (KBr pellet) of the film formed on the carbon steel surface after Research Journal of Chemical Sciences __________________________________________________________ ISSN 2231-606X Vol. 2(6), 72-81, June (2012) Res.J.Chem.SciInternational Science Congress Association 74 immersion in the solution containing 250ppm of SMV, 250ppm of melonic acid as shown in figure 1c. The VO stretching frequency of SMV shifted from 1385 cm-1 to 1386 cm-1resulting in the formation of Fe2+ -SMV complex. The –C=O stretching frequency shifted from 1719cm-1 to 1638 cm-1 and -OH stretching frequency shifted from 3407cm-1 to 3439cm-1. This suggest that oxygen atom of melonic acid co-coordinated with Fe2+ on the anodic sides of the metal surface, resulting in the formation of Fe2+- MA complex19-20. Table-1 Corossion rates (CR) and Inhibition efficiencies (IE) of carbon steel in aqueous solution containing 60 ppm of Cl in the absence and the presence of Inhibitors and Inhibition efficiency (IE) obtained by weight loss method Smv ppm Melonic Acid ppm IE% CR( mdd) 0 50 100 150 200 250 0 0 0 0 0 250 250 250 250 250 0 0 0 0 0 0 50 100 150 200 250 50 100 150 200 250 - 8 12 29 32 56 62 65 78 83 85 90 92 94 95 96 22.73 20.91 20.10 15.19 12.50 10.00 8.637 7.955 5.000 3.8641 3.4095 2.27 1.818 1.3638 1.3665 0.9092 Table-2 Synergism parameters of carbon steel immersed in in aqueous solution containing 60 ppm of Cl in the absence and the presence of Inhibitor Table-3 Distribution of F value between the inhibition efficiencies of smv –MA system Source of variance Sum of square Degree of freedom Mean square F Level of significance Between With in 1708 479 1 8 1708 115 14.8 p�0.05 MA ppm IE%SMV ppm IE% IE%1+2 S 50 100 150 200 250 62 65 78 83 85 0.63 0.65 0.78 0.83 0.85 250 250 250 250 250 56 56 56 56 56 0.56 0.56 0.56 0.56 0.56 90 92 94 95 96 0.90 0.92 0.94 0.95 0.96 1.6 1.9 1.6 1.4 1.6 Research Journal of Chemical Sciences ______ Vol. 2(6), 72-81, June (2012) International Science Congress Association Corrosion rate carbon steel in aqueous solution containing 60 ppm of Cl corrosion inhibition efficiencies by the weight loss method SMV ppm MA ppm SDS ppm 0 0 250 250 250 250 250 0 0 250 250 250 250 250 0 150 50 100 150 200 250 Figure-1(a) Pure SMV Film formed on surface of metal after immersion in aqueous solution containing 60 ppm of Cl 4000.0 3000 0.0102030405060708090 100.0 %T 3439.76 ______ _________________________________ ______________ International Science Congress Association Table-5 Corrosion rate carbon steel in aqueous solution containing 60 ppm of Cl - in presence and absence of inhibitors and the corrosion inhibition efficiencies by the weight loss method SDS ppm CR IE % Colony forming units ml - - 4.77 0.68 0.68 0.68 - - 67 78 98 98 98 1x10 5 2.5x101.9x104 1.5x103 1.1x103 4x102 nil Figure Pure melonic acid Figure-1(c) Film formed on surface of metal after immersion in aqueous solution containing 60 ppm of Cl 3000 200015001000 cm-1 2080.92 1638.65 1386.77 1117.73 717.91 ______________ _____ ISSN 2231-606X Res.J.Chem.Sci 75 in presence and absence of inhibitors and the Colony forming units Biocidal efficiency - 84 89 92 94 97 100 Figure -1(b) Pure melonic acid Film formed on surface of metal after immersion in aqueous solution containing 60 ppm of Cl - 400.0 717.91 Research Journal of Chemical Sciences __________________________________________________________ ISSN 2231-606X Vol. 2(6), 72-81, June (2012) Res.J.Chem.SciInternational Science Congress Association 76 Analysis of Polarization Study: The potentiodynamic polarization curves of metal immersed in aqueous solution containing 60 ppm of Cl figure 2. The corrosion potential (Ecorr), Tafel slope (bc= cathodic; ba= anodic, linear polarization resistance LPR and corrosion current Icorr are given in table 6. The potentiodynamic polarization curves of carbon steel immersed in aqueous solution containing 60 ppm of Cl are shown in figure 2. The corrosion parameters are given in table 6. When carbon steel is immersed in aqueous solution containing 60 ppm of Cl the corrosion potential Ecorr -542mV vs SCE. When 250ppm of SMV and 250ppm of melonic acid are added to the above system, the corrosion potential Ecorr-599 mV vs SCE shifted to the cathodic side. The cathodic Tafel slope (bc) is 193 and anodic Tafel slope (ba) is 198 mV/ Decade. It is inferred that the change of current with change in potential is less during cathodic polarization than during anodic polarization21-22. The LPR values is 2.0157 x 10cm and the corrosion current is 2.025x10-6 A/cm2 When carbon steel is immersed in aqueous solution containing 60 ppm of Cl- (figure 2). The corrosion potential is shifted to cathodic side -599 mV vs SCE. This suggests that a protective film is formed on the metal. The cathodic and anodic Tafel slopes were shows difference 72 mV /decade this shows change of current with change in potential is less during anodic polarization than during cathodic polarization. The LPR value increase from 2.0157 x 10 to 3.4693 x104 cm. The corrosion current decrease2.025 x 10-6 to 1.270 x 106 .An increase in LPR value and decrease in corrosion current are indicating ions protective film on the metal surface23. The polarization curves in the solution with no inhibitor were identical except for a change in the open current potential (OCP). All polarization curves in the metavanadate- containing solutions exhibited much lower OPR rates, and there was no influence of pH. This suggest that the local cathodes are blocked by V1 which greatly reduces the rate of oxygen reduction, since monovanadate appears to be the strongest corrosion inhibitor of the system, any coating scheme based on vanadium should release V1. This suggests that cathodic inhibition by vanadate is largely through the suppression of oxygen reduction with little effect on hydrogen evolution. AC Impedance spectra: AC impedance spectra of metals immersed in aqueous solution containing 60 ppm of Cl- are shown in figure 2. Nyquist plot and bode plots are shown in (figure 3 and 4). The charge transfer resistance (Rct) and double layer capacitance (Cdl) values (derived from Nyquist plots) and impedance , log(Z/) value derived from bode plots are given in table 7. When mild steel is immersed in aqueous solution containing 60 ppm of Cl the charge transfer resistance is 2363 cm and the double layer capacitance is 2.1919 x 10-9 F/cm2 (figure 4). The impedance log (Z/ ), value 3.237 When carbon steel immersed in aqueous solution containing 60ppm of Cl the charge transfer resistances increases from 2363 to 3679 cm and the double layer capacitance value decreases from 2.1919x10-9 to 1.38x10-10 F/cm. The impedance value increases from 3.237 to 3.55. This indicates the film formed on the metal surface24-25. SEM Analysis of Metal surface: The SEM image of magnification (x 500) of carbon steel specimen immersed in aqueous solution containing 60 ppm of Cl for 1 day in the absence and presence of inhibitor system are shown in figure 5 (a,b,c). The SEM micrographs of polished carbon steel surface (control) in figure 5 (a) shows the smooth surface of the metal this shows the absence and presence of any corrosion products formed on the metal surface26. The SEM micrographs of carbon steel surface immersed in aqueous solution containing 60 ppm of Cl in figure 5 (b) shows the roughness of the metal surface which indicates the corrosion of carbon steel in aqueous solution containing 60 ppm of Cl. figure 5 (c) indicates the presence of 250 ppm SMV and 250 ppm melonic acid, the surface coverage increases which in turn results in the formation of insoluble complex on the surface of the metal and the surface is covered by a thin layer of inhibitors effectively control the dissolution of carbon steel. Atomic Force Microscopy: Atomic force microscopy is a powerful technique for the gathering of roughness statistics from a variety of surfaces27-29. AFM is becoming an accepted method of roughness investigation. Atomic force microscopy provided direct insight in to the changes in the surface morphology take place at several hundred nanometers when topological changes owing to the initiation of corrosion and formation of protective film on the metal surface in presence and absence of inhibitors respectively.All atomic force microscopy images were obtained on vecco innova instrument operating in tapping mode in air. The scan size of all the AFM images are 5µm x 5 µm areas at a scan rate of 6.4 lines per second. The two-dimensional (2D) and three-dimensional (3D) AFM morphologies and the AFM cross-sectional profile for polished carbon steel surface (reference sample), carbon steel surface immersed in aqueous solution containing 60 ppm of Cl- (blank sample) and aqueous solution containing 60 ppm of Cl- 250 ppm of SMV and 250 ppm melonic acid are shown in figure 6 (a,b,c), (d,e,f) respectively. Research Journal of Chemical Sciences __________________________________________________________ ISSN 2231-606X Vol. 2(6), 72-81, June (2012) Res.J.Chem.SciInternational Science Congress Association 77 Root mean square Roughness, average roughness and maximum peak to valley Height: AFM image analysis was performed to obtain the average roughness, Ra (the average deviation of all points roughness profile from a mean line over the evaluation length), root –mean – square roughness, Rq (the average of the measured height deviations taken within the evaluation length and measured from the mean line) and the maximum peak to valley (P-V) height values (largest single peak-to-valley height in five adjoining sampling heights). Rq is much more sensitive than Ra to large and small height deviations from the mean. The value of Rq, Ra and P-V height for the polished carbon steel surface (reference sample) are 3.41nm, 4.33 nm and 43.5 nm respectively. This shows a more homogenous surface, with some places in where the height is lower than the average depth. Figure 6 (a) displays the un-corroded metal surface. The slight roughness observed on the polished metal surface is due to atmospheric corrosion. The rms roughness, average roughness and P-V height values for the carbon steel surface immersed in aqueous solution containing 60 ppm of Cl are 21.2662 nm, 17.2138 nm and 63.5 nm respectively. The data suggest that the carbon steel surface immersed in aqueous solution containing 60 ppm of Cl has a greater surface roughness than the polished metal surface, which shows that the unprotected carbon steel surface is rougher and were due to the corrosion of carbon steel in aqueous solution containing 60 ppm of Cl environment. Figure 6 (b) displays corroded metal surface with few pits. The formulation consisting of 250 ppm SMV and 250 ppm melonic acid in aqueous solution containing 60 ppm of Clreduces the Rq value of 4.1nm and the average roughness is significantly reduced to 2.4 nm when compared with 34 nm for carbon steel surface immersed in aqueous solution containing 60 ppm of Cl. The maximum peak to valley height was also reduced to 34 nm. These parameters confirm that the surface appears smoother. The smoothness of the surface is due to the formation of a protective film of Fe2+- SMV complex and Fe2+- MA complex on the metal surface thereby inhibiting the corrosion of carbon steel which confirms the formation of the film on the metal surface, which is protective in nature. Table-6 Corrosion parameter of carbon steel immersed in aqueous solution containing 60 ppm of Cl- obtained by polarization study are given System Ecorr (mV vs SCE) bc (mvVs /decade) ba (mv /decade) LPR cmIcorr (A/ cm) Aqueous solution containing 60 ppm of ClAqueous solution containing 60 ppm of Cl + 250 ppm SMV+250 ppm MA - 542 -599 193 162 198 270 2.0157 x 104 3.4693 x 104 2.025 x10-6 1.270x 10-6 Table-7 Impendence parameter of carbon steel immersed in aqueous solution containing 60 ppm of Cl- in the presence and absence of inhibitor system obtained from AC impedance curves system Nyquist plot Bode plot Rct cm2 Cdl F/cm2 Impedance log(Z/) Aqueous solution containing 60 ppm of Cl- Aqueous solution containing 60 ppm of Cl + 250 ppm SMV+250 ppm MA 2363 4264 2.1919x10-9 1..19x 10-9 3.237 3.55 Research Journal of Chemical Sciences __________________________________________________________ ISSN 2231-606X Vol. 2(6), 72-81, June (2012) Res.J.Chem.SciInternational Science Congress Association 78 Figure-2 Polarization curves of carbon steel immersed in various test solutions, (a) Aqueous solution containing 60ppm of Cl- (b) Aqueous solution containing 60ppm of Cl+250 ppm SMV+ 250 ppm MA Figure-3 AC Impedance spectra of carbon steel immersed in various test solution, (a) Aqueous solution containing 60ppm of Cl(b) Cl 60ppm (Nyquist) Cl- 60ppm+ 250ppm SMV+250ppm MA (Nyquist) Figure-4 AC Impedance spectra of carbon steel immersed in various test solution, (a) Cl 60ppm (impedance-bode), (b) Cl 60ppm + 250ppm SMV+250ppm MA (impedance-bode)       a b b Research Journal of Chemical Sciences ______ Vol. 2(6), 72-81, June (2012) International Science Congress Association (a) SEM micrographs of (a) Polished carbon steel (control); Magnification solution containing 60 ppm of Cl ; Magnification of Cl + 250 ppm of SMV+ 250 ppm of MA; Magnificati Summary of the average roughness (Ra), rms roughness (Rq), maximum peak surface immersed in different environments Samples RMS(Rq) Roughness(nm) Polished carbon steel(control) 60 ppm of Cl 60 ppm of Cl+SMV(250 ppm) + MA(250 ppm) 17.2138 AFM image of the surface of a) polished carbon steel (control), carbon steel immersed in aqueous solution containing 60 ppm of Cl , carbon steel immersed in aqueous solution containing 60 ppm of Cl (a) ______ _________________________________ ______________ International Science Congress Association (b) Figure-5 SEM micrographs of (a) Polished carbon steel (control); Magnification – X 500. (b) Carbon steel immersed in aqueous ; Magnification – X 500. (c) Carbon steel immersed in aqueous solution containing 60 ppm + 250 ppm of SMV+ 250 ppm of MA; Magnificati on –X 500 Table-8 Summary of the average roughness (Ra), rms roughness (Rq), maximum peak –to- valley height (P_V) va surface immersed in different environments RMS(Rq) Roughness(nm) Average(Ra) Roughness(nm) Maximum peak 4.33 17.2138 4.1 3.41 21.2662 2.4 Figure-6 AFM image of the surface of a) polished carbon steel (control), carbon steel immersed in aqueous solution containing 60 , carbon steel immersed in aqueous solution containing 60 ppm of Cl - + 250 ppm of SMV+ 250 ppm of MA (b) (c) ______________ _____ ISSN 2231-606X Res.J.Chem.Sci 79 (c) X 500. (b) Carbon steel immersed in aqueous X 500. (c) Carbon steel immersed in aqueous solution containing 60 ppm valley height (P_V) va lue for carbon steel Maximum peak -to-valley height(nm) 43.5 63.5 34 AFM image of the surface of a) polished carbon steel (control), carbon steel immersed in aqueous solution containing 60 + 250 ppm of SMV+ 250 ppm of MA Research Journal of Chemical Sciences __________________________________________________________ ISSN 2231-606X Vol. 2(6), 72-81, June (2012) Res.J.Chem.SciInternational Science Congress Association 80 (d) (e) (f) Figure-6 Cross sectional profile, which are corresponding to as shown broken lines AFM image of the surface of polished carbon steel (control) carbon steel immersed in aqueous solution containing 60 ppm of Cl- carbon steel immersed in aqueous solution containing 60 ppm of Cl+ 250 ppm of SMV+ 250 ppm of MA ConclusionThe present study leads to the following conclusion: The formulation consisting of 250 ppm of MA and 250 ppm of SMV offers 98% inhibition efficiency to carbon steel immersed in aqueous solution containing 60 ppm Cl. Polarization study reveals that this formulation controls anodic reaction predominantly. AC impedance spectra reveal that a protective film formed on the metal surface. FTIR spectra and also reveal that the protective film consists of Fe2+-SMV complex and Fe2+-MA complex. SEM and AFM study confirm that protective film formed on the metal surface AcknowledgementThe authors are thankful to their respective management and UGC for their encouragement. References1.Kending M. and Buchheit R.G., Corrosion Inhibition of Aluminium and Aluminium Alloys by Soluble Chromates, Chromate Coatings and Chromate-Free Coatings Corrosion (Houston), 59(5), 379-400 (2003)2.Iannuzzi M., Young T. and Frankel G.S, Aluminum Alloy Corrosion Inhibition by Vanadates J. Electrochem. Soc.,153(12), B533-B541 (2006) 3.Guan Hand Buchheit R.G, Corrosion (Houston), 60, 284-294 (2004)4.Ralston K.D., Chrisanti S., Young T.L. and Buchheit R.G., Corrosion Inhibition of Aluminum Alloy 2024-T3 by Aqueous Vanadium Species, J. Electrochem. Soc., 155(7), C350-C359 (2008) 5.Cook R.L. and T. aylor S.R., Characterization of Inhibitor Release from Zn-Al- [V10O28] 6–Hydrotalcite Pigments and Corrosion Protection from Hydrotalcite- Pigmented Epoxy Coatings Corrosion (Houston), 56, 321-333(2000)6.Buchheit R.G., Guan H., Mahajanam S., and Wong F., Active corrosion protection and corrosion sensing in chromate-free organic coatings, Prog. Org. Coat., 47(9)174-182 (2003) 7.Chambers B.D., Taylor S.R., and Kending M.W., Corrosion (Houston), 51, 480-489 (2005)8.Crans D.C. and Tracey A.S., Peroxo-, Hydroxylamido- and acac-derived Vanadium Complexes, ACS Symp. Ser., 7(11), 2-29 (1998)9.Petterson L. and Elvigson K., ACS Symp, Ser., 7(11), 30 (1998)10.Petterson L., Equilibria of polyoxometalates in aqueous solution, Mol. Eng., 3(1-3), 29-42 (1993)11.Cruywagen J.J., Mo (VI) and W(VI) removal from water samples by acid-treated high area carbon cloth, Adv. Inorg. Chem., 49 127-182 (2000)12.Holleman A.F. and Wiberg E., Inorganic chemistry, Academic Press, New York (2011)13.Frankel G.S. and. Mc Creery R.L, Releasable corrosion inhibitor compositions, Interface, (USA) 34-38 (2001)14.Campestrini P., Goeminne G., Terryn H. and Vereecken J., Corrosion Resistance of Cr (III)Based Conversion Layer on Zinc Coatingsin Comparison with a raditional Cr (VI)Based Passivation Treatment, J. Electrochem. Soc., 151, B59- B70 (2004)15.Crompton J.S, Andrews P.R. and Alpine E.M, Characteristics of a conversion coating on aluminium Surf., Interface Anal., 13, 160 (1988)16.Wranglen G., Introduction to corrosion and protection of metals, London: chapman and Hall 236 (1985) Research Journal of Chemical Sciences __________________________________________________________ ISSN 2231-606X Vol. 2(6), 72-81, June (2012) Res.J.Chem.SciInternational Science Congress Association 81 17.Rajendran S., Vaibhavi S. and Anthony N., Inhibitive action of hydroquinone - Zn2+ system in controlling the corrosion of carbon steel in well watercorrosion, 59, 529-534 (2003)18.Rajendran S., Raji A., Arokiaselvi A., Rosaly J. and Thangaswamy, Parents' education and achievement scores in chem- istry Edutracks, 6, 30-34 (2007) 19.Agnesia Kanimozhi S. and Rajendran S., Inhibitive Properties of Sodium tungstate-Zn2+ System and its Synergism with HEDP, International J. Electro Chem Sci., , 353-368 (2009)20.Silver stein R.M, Bassler G.C and. Morrill T.C., Spectroscopic Identification of organic compound, Newyork, NY: John Wiley and sons, 95 (1986)21.Sathyabama J., Susai R. Arokia S.J. and John A.A, Methyl orange as corrosion inhibitor for carbon steel in well water Indian, J chem Tech, 15, 462-466 (2008)22.Rajendran S., Sridevi S.P., Anthony N., John Amalraj A. and Sundaravadivelu N., Corrosion behaviour of carbon steel in polyvinyl alcohol, Anti Corro. Methods Maerial, 52, 102-107 (2005)23.Felicia Rajammal Selvarani, Santhanalakshmi S., Wilson Sahayaraja J., John Amalraj A. and Susai Rajendran,Corrosion inhibition of carbon steel by succinic acid – Zn2+ system, Bull.Electrochemistry, 20, 561-565 (2004) 24.Sathiyabama J., Susai Rajendran, Arokia selvi J., Bull. Electrochemistry, Methyl orange as corrosion inhibitor for carbon steel in well water22, 363-370 (2006)25.Susai Rajendran, Manimaran M., Wilson Sahayaraja J., Sathiyabama J., John Amalraj A. and Palaniswamy N., Trans., SASET, 41, 462-466 (2006) 26.Rajendran S., Manimaran M., Investigation of inhibitive action of urea- zn2+ system in the corrosion control of carbon steel in sea water, International Journal of Engineering Science and Technology (IJEST), 3(11), 8048-8060 (2011) 27.Dumas Ph., Butffakhreddine B., Am C. OVatel E., Ands, Galindo R. and Salvan F., Quantitative Microroughness Analysis down to the Nanometer Scale Europhys, Lett, 22, 717-722 (1993)28.Bennet J.M, Jahannir J., Podlesny J.C, Baiter T. Land Hobbs D.T, Analysis of nano film by atomic force microscopy Appl, Opt, 43, 213-230 (1995)29.Amra C., Deumie C., Torricini D., Roche P., Galindo R., Dumas P. and Salvan F., Combination of surface characterization techniques for investigating optical thin-film components Int, Symp. on Optical Inference coating, SPIE 2253 614-630 (1994)