Corrosion Inhibition Effect of Tetra Methyl Ammonium Bromide (TMAB) in Acidic Media

8/12/2019 Corrosion Inhibition Effect of Tetra Methyl Ammonium Bromide (TMAB) in Acidic Media

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Journal of Chemical Engineering and Materials Science Vol. 3(5), pp. 86-95, December 2012Available online at http://www.academicjournals.org/JCEMSDOI: 10.5897/JCEMS11.032ISSN-2141-6605 JCEMS 2012 Academic Journals

Full Length Research Paper

Corrosion inhibition of mild steel in sulphuric acidsolutions by using tetra methyl ammonium bromide

(TMAB)

Arwind Kumar Dubey1*, Gurmeet Singh2and Kamlesh Tiwari3

1Reliability and Technical Services (RTSD), P. O. Box 10002, Petrokemya, Jubail Industrial Area, Jubail, 31961, SaudiArabia.

2Corrosion Research Group, Department of Chemistry, University of Delhi-110007, India.3

Department of Mathematics, Patel Group of Institution Bhopal, India.Accepted 4 December, 2012

The corrosion inhibition of mild steel in one normal sulphuric acid solution by tetra methyl ammoniumbromide (TMAB) has been studied in relation to the concentration of the inhibitor as well as thetemperature using electrochemical polarization (galvanostatic and potentiostatic polarizations)techniques. The results were supplemented with scanning electron microcopy and infra-redspectroscopy. All the methods employed are in reasonable agreement. There is no particularrelationship of inhibition with concentration and temperatures. The thermodynamic functions ofdissolution and adsorption processes were calculated from experimental polarization data and theinterpretation of the results are given. Adsorption of TMAB was found to follow the Langmuirsadsorption isotherm. TMAB is a mixed type of inhibitor.

Key words: Tetra methyl ammonium bromide (TMAB), corrosion inhibitors, mild steel, sulphuric acid (H2SO4),thermodynamic functions, adsorption process, scanning electron microscope (SEM), infrared spectroscopy (IR)spectra.

INTRODUCTION

Acid solutions are generally used for the removal of rustand scale in several industrial processes. Inhibitors aregenerally used in these processes to control the metaldissolution. H2SO4is widely used in the pickling of steeland ferrous alloys (Bentiss et al., 1999). To make securefrom attack of acid, inhibitors are frequently used.Organic nitrogen compounds on the corrosion behavior ofiron and steel in acidic solutions are usually employed fortheir rapid action (Chetouani et al., 2002). If we can provethat adsorption of certain atoms retards corrosion, thismight be the easiest and cleanest, and probably the mosteconomic, approach to corrosion inhibition. The use ofinhibitors takes more and more attention until now. While

*Corresponding author. Email: [email protected]. Tel:+966-59-3713551.

there are differences among the theories developed toexplain effects of some inhibitors, there is a commonconsensus about the manner in which the various kindsof inhibitors work (Tauhami et al., 2000). A study of themechanism of the action of corrosion inhibitors hasrelevance both from the point of view of the search fonew inhibitors and also for their effective use. Acidsolutions are generally used for the removal oundesirable scale and rust in several industriaprocesses. Generally, the use of organic inhibitors tocontrol the metal dissolution is one of the commontechniques, and during the past decade many inhibitorshave been studied in different media (Elkadi et al., 2000).

The aim of this work is to study the inhibiting effect otetra methyl ammonium bromide (TMAB) on mild steel inone normal sulphuric acid solution. Galvanostatic andpotentiostatic polarizations were done. The effects oinhibitor concentration at different temperatures were


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studied. The results were supplemented by scanningelectron microscope (SEM) and infraredspectroscopy (IR) spectra studies.

EXPERIMENTATION

Corrosion inhibitor compound

The organic additive tetra methyl ammonium bromide (TMAB) isused as the corrosion inhibitor.

Chemical composition of mild steel

Mild steel refers to low carbon steel which is usually used forstructural applications. With too little carbon content to throughharden it is weldable, which expands the possible applications ofmild steel. The experiments were performed with cold rolled mildsteel specimen. Mild steel coupons of chemical composition(C=0.20%, Mn=.1.00%, Si=0.05%, S=0.025%, P=0.25% andFe=98%) have been used.

Solutions

The aggressive solutions were made of AR grade H2SO4. Onenormal concentration of acid was prepared using doubled distilledwater. The concentrations of inhibitor employed were 10 -7, 10-5and10-3M.

Electrodes

Work ing electrode

Design of working electrodes (WE) is diverse. Most commons inexperiments are to study mechanism and kinetics in the laboratory.

An essential feature is that the electrode should not reactchemically with the solvent or solution components. It is desirable tohave an even current and potential distribution and hence a cell tobe designed, so that all points on working electrode surface aregeometrically equivalent with respect to the secondary electrode.

Reference electrod e

The role of the reference electrode (RE) is to provide a fixedpotential which does not vary during the experiments. The REserves dual purposes of providing a thermodynamic reference andalso isolating WE from the system.

Auxi l ia ry e lec trode (count er e lec trode)

The purpose of the counter electrode (CE) is to supply the currentrequired by the working electrode without limiting the measuredresponse of the cell. It is essential that the electrode process isdecomposition of the electrolyte, so that the current flows readilywithout the need for a large over potential.

Luggin capillary

The luggin capillary in a laboratory cell is made from glass. It isgenerally filled with the test solution. The luggin holds the referenceelectrode. The tip of the luggin capillary near the working electrode

Dubey et al. 87

is open to the test solution. The reference electrode senses thesolution potential at this open tip. Note that the luggin tip issignificantly smaller than the reference electrode itself. The luggincapillary allows sensing the solution potential close to the workingelectrode without the adverse effects that occur when the largereference electrode is placed near the working electrode. A luggincapillary can be used to bring the potential measuring point in closeproximity to the working electrode under investigation. Such adevice can be made of any material provided it is inert to theelectrolytic environment. It basically consists of a bent tube with alarge enough opening to accommodate a reference electrode and ausually much smaller opening only large enough to insure diffusionmovement of the electrolyte. The device minimizes any iR drop inthe electrolyte associated with the passage of current in anelectrochemical cell.

Surface treatments of the working electrode

The surfaces of carbon steel specimens were abraded successivelyby different grade of metallographic emery papers until the surfacesappear free from scratches and other apparent defects, thendegreased in hot acetone, washed with bi-distilled water and finally

dried. The surface treatment was carried out immediately beforeeach experiment of corrosion tests (Abd El-Kader et al., 1998).

RESULTS AND DISCUSSION

Open circuit potential measurements

The electrochemical behavior of mild steel in 1 N H2SO4was studied on the basis of the change in corrosionpotentials (Ecorr) with time. It is send that in absence othe inhibitor molecules, the open circuit potential tendsfrom the moment of immersion towards more negativevalue. This behavior represents the break down of thepre-immersion, air formed oxide film on the mild steesurface. In presence of different concentrations of theinhibitor the steady state potentials of the workingelectrodes were shifted towards more positive valuesdenoting passivation of the mild steel (Putilova et al.1960).

Galvanostatic polarization measurements

The cathodic and anodic polarization curves for thesesolutions with and without any inhibitor concentrations a298, 308, 318 and 328K are plotted. Logarithms o

current densities have been plotted against thecorresponding potentials. From these graphs we obtainedthe values of corrosion potential (Ecorr), corrosion curren(log icorr), anodic Tafel region (ba), cathodic Tafel region(bc), corrosion inhibition efficiency (I%) and surfacecoverage (). These values are mentioned in Table.1The one graph obtained at 298K is given in the Figure 1.

At lower temperature the decrease in corrosion currenwith increase in TMAB concentrations is much morepronounced than that at higher temperatures. At aparticular TMAB concentrations, the corrosion current ishigher at higher temperature and this is observes at a


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88 J. Chem. Eng. Mater. Sci.

Table 1.Corrosion electrochemical parameters for mild steel grade IS-226 in 1 N H 2SO4 in the absence and in the presence of TMAB asadditive.

Temperature

(K)

Concentration

(M)

Corrosion potential

E corr (mV)

Log icorr

(A/cm2)

bc

(mV/dec)

ba

(mV/dec)

Corrosion inhibition

efficiency (I%)

Surface

coverage ()1/1-

298

0 490 3.00 80 35 0 0 0

10

-7

460 2.60 125 100 60.2 0.602 1.5110-5 460 2.60 145 103 60.2 0.602 1.5110-3 460 2.40 155 103 74.0 0.740 2.84

308

0 520 3.00 115 85 0 0 0

10-7 464 2.12 140 100 86.9 0.869 6.6310-5 456 2.75 148 78 43.8 0.438 0.77

10-3 452 2.05 148 100 88.8 0.888 7.92

318

0 520 3.12 125 80 0 0 010-7 480 2.75 56 40 57.9 0.570 2.3210-5 400 2.75 124 48 57.0 0.570 2.32

10-3 406 2.50 188 400 76.0 0.76 3.12

328

0 500 3.00 165 76 0 0 010-7 500 2.68 304 24 52.2 0.522 1.09

10-5 500 2.55 136 72 64.4 0.644 1.8010-3 540 2.50 124 124 68.4 0.684 2.16

-1200

-900

-600

-300

0

2 3 4 5

log Current density(C.D.) Acm

-2

E(mV/SCE)

Figure 1. Galvanostatic polarization curves of mild steel in one normal solution containing differentconcentrations of tetra methyl ammonium bromide (TMAB) at 298K. Where is for 1 N H2SO4, is for 10

-7MTMAB solution, + is for 10-5M TMAB solution, x is for 10 -3M TMAB solution.

concentrations. In the corrosion process the little changein the corrosion potentials suggest that TMAB controlsboth the cathodic hydrogen evolution as well as irondissolution reactions. The inhibitor at higher temperatureexerts a greater influence on the cathodic process than

that the anodic process. During metal dissolutionreaction metal oxide and metal hydroxide reaction startsthe chemical association of TMAB molecules, with themetal surface through the oxygen lone pair of electroninteraction turning to chemical reaction and probably


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Dubey et al. 89

30

40

50

60

70

80

90

100

-8 -7 -6 -5 -4 -3 -2

log C

InhibitionEfficie

ncy(I%

Figure 2.Variation of percentage corrosion inhibition efficiency (I%) with inhibitor concentration formild steel coupon in 1N H2SO4containing various inhibitors at 298, 308, 318 and 328K. Where isfor 298K,is for 308K, is for 318K, X is for 328K.

forming intermediates species (M-In)adsor (M-In-OH)adsor(M-H-In)ads and thereby resulting in irregular slopes.Corrosion current density decreases with concentrationand its inhibition efficiency decreases with the rise oftemperature.

The peculiar behavior of TMAB at higher temperaturesmay be due to the joint effects of:

(i) reaction of the inhibitor with electrode surface(ii) decomposition of inhibitor to the some othercompound in the acid solutions and thereby changing thekinetics of cathodic and anodic reactions in a differentmanner.

The graph between corrosion current and concentrationis plotted in Figure 1 and the graph between inhibitionefficiency with concentration is plotted in the Figure 2. Itshows that there is no regular order of inhibition efficiencywith concentration.

TMAB affects the corrosion of mild steel in acidmedium in the form of protonated organic molecule and

the prevailing inhibitor effect is anodic rather thancathodic at ordinary temperature (298K) and at lowerconcentrations. At higher temperatures the inhibitor actsboth in cathodic as well as in the anodic. At alltemperatures it is seen that inhibition effect is more athigher concentration than at lower concentration. At allconcentrations of TMAB, the change in corrosionpotentials from that in uninhibited solution is lower exceptat higher temperature where it remain unchanged. Thisindicates that it is a mixed type of inhibitor with a slightpredominance of anodic effect except at 328K.

Effect of temperature and adsorption isotherm

In order to study the effect of temperature on corrosioninhibition of mild steel in the acid reaction and todetermine the activation energy of the corrosion processthe galvonostatic polarization studies were done avarious temperatures (298 to 328K) in the absence and inthe presence of TMAB at different concentrations. The

corresponding results were given in Table 1. The changeof corrosion current with temperature is plotted in theFigure 3. We note that the corrosion rate increases withrise of temperature both in inhibited and uninhibited acidsolutions. Figure 4 shows the change of surfacecoverage with temperature whereas Figure 5 shows aplot of log (/1-) versus log C, where is the surfacecovered by inhibitor molecules and C is the inhibitoconcentration in mol-1. The Gibbs energy of adsorption(Gads) was calculated for the following equation:

/1- = 1/55.55 E exp (-Gads/RT)

The surface coverage value was evaluated usingvalues of inhibition efficiency.

The inhibition behaviour of TMAB at differenconcentrations and different temperatures assumingchange in the mechanism of both the hydrogen evolutionreaction and iron dissolution and the degree of coverage can be obtained using the equation

=1-(iinh/iuninh)

It is assumed that inhibitor gives monolayer adsorption


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0

0.5

1

1.5

2

2.5

3

3.5

2.95 3 3.05 3.1 3.15 3.2 3.25 3.3 3.35

1/ T X 103K

-1

logicor

r

Figure 3. Variation of corrosion current density with temperature (298, 308, 318 and 328K) at differentinhibitor concentration for mild steel coupon in 1N H2SO4Where is for 1N H2SO4, is for 10

-7M TMABsolution, + is for 10-5M TMAB solution, x is for 10 -3M TMAB solution.

-1

-0.5

0

0.5

1

1.5

2

2.95 3 3.05 3.1 3.15 3.2 3.25 3.3 3.35

1/T X103K

-1

log/

1-

Figure 4.Variation of surface coverage area with temperature (298, 308, 318 and 328K) at different inhibitorconcentration for mild steel coupon in 1N H2SO4Where is is for 1N H2SO4, is for 10

-7M TMAB solution,is + for 10-5M TMAB solution, x is for 10 -3M TMAB solution.

coverage at any instant fraction () of the metal surface ina uniform or random manner and that the free fraction ()of the metals surface (1- ) reacts with and as it does inthe absence of inhibitor. The (1- ) can be assured to beequal to ic/i0 and can be calculated readily from theresults within a certain range of inhibitor. The surfacecoverage due to the progress of adsorption and

desorption also changes with temperature. It shows thathis inhibitor belong to the second category of Putilovasclassification of inhibitor, which characterized by no effecon the temperature coefficient. This type of inhibitoaccording to Putilova retards corrosion at ordinarytemperature but efficiency is not reduced considerably aelevated temperature (Schweinsberg et al., 1988). The


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Dubey et al. 91

-0.5

0

0.5

1

1.5

2

-8 -7 -6 -5 -4 -3 -2

log C

log/

1-

Figure 5. Variation of surface coverage area with inhibitor concentration for mild steel coupon in 1 NH2SO4containing various inhibitors at 298, 308, 318 and 328K. Where is for 298K, denotes for 308K, is for 318K, X is for 328K.

series of isotherm obtained over a range of temperaturethat is, 298, 308,318 and 328K yielded reasonable valuesof heats of adsorption when the function of log ( /1- )plotted against the reciprocals of absolute temperature.Plots of inhibited corrosion rates versus the reciprocal oftemperatures for a series of constant inhibitorconcentration show that the net activation energy ofcorrosion energy of corrosion process shows irregulartrend with concentration of TMAB in 1 N H2SO4solution.The corrosion behavior of mild steel surface and surfacecoverage shows irregular relationship with inhibitorconcentration. The values of activation energy (Ea) werecalculated using the Arrhenius equation:

Ea = -2.3003 R d (log ic)/d (1/T)

Where R is the universal gas constant and T is thetemperature in Kelvin. The average activation energy ofTMAB is 66.72 kJmol-1.

The heat of adsorption Q at different temperatureswere calculated from Langmuirs adsorption isotherm

equationlog /1- = log A+ log C Q/RT

TheaverageheatofadsorptionforTMABis28.33kJmol-1.From the surface coverage data of the TMAB, it is

inferred that the adsorption of the TMAB on the ironsurface inhibits corrosion. Generally, four types ofadsorption may take place, involving organic molecule atthe metal solution interface (Fouda et al., 1986).

(i) The electrolytic attraction between charged molecule

and the charged metal.(ii) Interaction of unshared electron pairs in the moleculeswith the metal(iii) Interaction of pi electrons with metal and(iv) Combination of the above points.

Inhibition efficiency depends on several factors, such asthe number of adsorption sites and their charge densitymolecular size, heat of hydrogenation, mode ointeraction with the metal surface and the formation ometallic complexes (Hackerman et al., 1966).

The action of amine inhibitor molecules is due to theadsorption of the inhibitor molecules on exposed metasurface. Amines may be adsorbed over the metal surfacein the form of neutral molecules involving replacements owater molecules from the metal surface as:

Amine(s) + nH2Oads Amineads+ nH2O (s)

And sharing of electron between the N atom the inhibitomolecules and metal surface or by the electrostaticinteraction between the positively charged N atom andnegatively charged metal surface. The inhibitiveproperties of amines are mainly dependent on theelectron densities around the nitrogen atoms; the highethe electron densities around the nitrogen atoms, moreeffective are inhibitor. Due to adsorption, inhibitomolecules block the reaction sites and reduce the rate ocorrosion reaction.

The inhibitor molecules inhibit the corrosion of mildsteel by adsorption on the mild steel-solution surface; theadsorption provides the information about the interaction


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-1.5

0.5

2.5

4.5

-500 500 1500 2500E mV /SCE

logcurrentdensityAcm-2

Figure 6. Potentiostatic polarization curves of mild steel in one normal solution containing differentconcentrations of tetra methyl ammonium bromide (TMAB). Where is for 1 N H2SO4, is for 10-7M TMAB

solution, + is for 10-5M TMAB solution, x is for 10 -3M TMAB solution.

Table 2. Passivation data for TMAB obtained by potentiostatic polarization.

Additive Critical current density, Icric(A/cm2) Passivation current density, Ip (A/cm

2) Ranges of Epp(V )

1N H2SO4 79.4 50.1 110-134010-7M 380 1.58 400-1396

10-5 M 380 1.85 380-146210-3M 380 1.58 60-

around the adsorbed molecules themselves as well astheir interaction with electrode surface. A correlationbetween and concentration of inhibitor in the electrolytecan be represented by the Langmuirs adsorptionequation as

=KC (1+ KC)

According to Bockris and Drazic, the inhibitionmechanism could be explained by Fe-(Inh)ads reactionintermediated as below.

Fe+ Inh (Inh)ads Fen+

+ ne-

+ Inh

The adsorbed layer combats the action of sulphuric acidsolution and enhances protection of the metal surface.When there is sufficient Fe(Inh)ads to cover the metalsurface (if the inhibitor concentration was low or theadsorption rate was slow), metal dissolution would takeplace at sites on the mill steel surface which are free ofFe-(Inh)ads which are free of Fe-(Inh)ads. With highinhibitor concentration a compact and coherent inhibitorover layer forms on mild steel surface, reducing chemicalattack on the metal. The adsorption of an organic

molecule on the surface of the mild steel is regarded as asubstitution of adsorption process between the organiccompound in the aqueous phase (Orgaq) and the watemolecules adsorbed on the mild steel surface (H2Oams).

Org aq + x H2Oams Org ams + x H2Oaq

Where x is the size ratio, in terms of the number of watemolecules replaced by an adsorbate molecules. Whenthe equilibrium of the process described in the aboveequation is reached, it is possible to obtain differenexpression of the adsorption isotherm plots.

Potentiostatic polarization measurements

A detailed study of steady state potentiostatic polarizationbehavior of anodic dissolution of mild steel in thepresence of TMAB was made in 1 N H2SO4 solution aroom temperature (298K). The graph between potentiaand current density is plotted for 1 N H2SO4, 10

-7M, 10-5Mand 10-3M solution of TMAB plotted in Figure 6 and thevalues of critical current density (icrit), passive current (ipand passivation potential (Epp) are mentioned in the Table2. It is seen from the table and figure that ip, Epp become


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Dubey et al. 93

Figure 7. Scanning electron micrographs of mild steel samples (at 2000 magnification) (A) after

polishing (B) after immersion in 1 N H2SO4for 24 h (C) after immersion in 10-3

M TMAB solution for24 h (D) after immersion in 10 -7M TMAB solution for 24 h.

lower and ic becomes higher on comparison with thedissolution in the absence of the TMAB. Hence it can beconcluded that TMAB is a good passivator. H3O, H2SO4,SO4 and OH ions present in the solution interfere withformation of resistance layer because of adsorption ofTMAB on the metal surface with the help of alreadyadsorbed anions present in the solution,. It is commonlyaccepted that kinetic of iron anodic oxidation in aciddepends on the adsorbed intermediates FeOHads. An iron

anodic oxidation mechanism, which is valid in thepresence of inhibitor, could be similar to that discussedby MacCafferty and Hackerman (1973).

Fe + H2 Fe.H2Oads (1)Fe.H2O + X FeOH

- + H2O (2)Fe.H2 ads+ X FeX ads + H2O (3)FeOH-ads FeOH ads + e

- (4)FeX ads FeX

+ads + e

- (5)FeOH ads+ FeX

+ads FeX ads+ FeOH

+ (6)FeOH ++ H + Fe2++ H2O (7)

where the species X are the inhibitor molecule, in our

case. This mechanism shows that the anodic reactionkinetics is affected by two intermediates: one involvingadsorbed hydroxyl (FeOHads) and the other involving theadsorbed inhibitor molecule (FeXads). The main effect ofthe petroleum content on the value of corrosion rate mayaccount for the high effect exerted by the organic inhibitormolecule on the anodic reaction. The rate of anodicdissolution (step 4) depends to the product of step (2),but the two competitive steps (2) and (3) are based onthe Fe.H2Oads. Displacements of the adsorbed watermolecule by the species X, can have effect on the step(4). Every condition, such as molecular shape or

localized partial charges or by another view, strichindrance of X molecule to the metal surface, canvariegate the above competition. The influence of twosolvents on each inhibitor molecule causes dispersion oinhibition ability. This dispersion may accelerate from theadsorption of the inhibitor molecule onto the differenmetal surface sites having different activation energies fochemisorptions (lattice planes, edges, kinks, dislocationsinhomogeneities, etc.). The passive film on mild steel is a

hydrated oxide film having a gel like structure andprotons present in the passive film are pulled out by theanodic polarizations. As per Pyun hydrogen is ionized toprotons in the passive film due to anodic character of thepassive film. As hydrogen is charged into passive filmthe average concentration of protons increases theamount of hydrogen containing species such as H2O andOH- within the passive films and with the increase opotential beyond passive ranges the passive films brakedto give trans-passive region with evolution of oxygen inthis range.

It may be noted that TMAB form a passive layer oresistive; layer with the help of already adsorbed anions

present in the solutions. The cooperative adsorptionleads to formation of the complexes of the types (M-InOH) adsor (M-OH-In) adsor (M-In-A)ads, where A is any othe already adsorbed anions on the metal surface whichgives large potential regions.

Scanning electron microscopy (SEM)

In the present work SEM was operated at 10 KV, sincethe secondary electrons emanate from a depth of abou10 or less from corroded surface. Figure 7 (A) shows


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Figure 8.Infra-red spectra of tetra methyl ammonium bromide (TMAB).

the micrographs by SEM of the unexposed surface of theuncorroded surface of mild steel which is found to beabsolutely free from any noticeable defect such as cracksand pits. Polishing scratches are also visible. Figure 8 (B,C, and D) show micrographs by SEM of mild steelspecimens exposed in 1 N H2SO4, 10

-7M TMAB, 10-5 MTMAB, and 10-3 M TMAB solutions at a magnification of2000. Uniform corrosion was observed. Flakes are seenwhich show corrosion products are observed in themicrographs. The electron micrographs reveal that, thesurface was strongly damaged owing to corrosion inabsence of the inhibitor but in the presence of inhibitorthere is a much less damage on the surface. This isattributed to the formation of a good protective film on thecarbon steel surface. It is quite apparent from the

micrographs the uniform products like metal hydrides andit oxides are also visible. On comparison TMAB act asgood inhibitor at higher concentration. The extent ofinhibitor is reduced considerably in the presence of lesserconcentration of TMAB.

Infra-red spectroscopy

Silica gel was specially chosen because finally dividedsilica gels crystals have larger surface area for adsorption

of organic molecules. Thus sufficient adsorbed materiacan be included in the sample to yield a spectrum omoderate intensity. Further with such finally dividedmaterials radiations looses by scattering are not largeespecially at frequencies below 3000 cm-1. The variouspeaks in the spectra of pure TMAB and TMAB adsorbedover silica gel are given in the Figures 8 and 9. Thepeaks have been tabulated in the Table 3. On comparingthe spectra of pure silica with the spectra of adsorbedTMAB molecule over silica, it is observes that certainpeaks have been disappeared completely and somehave shifted to higher frequency region proving that someadsorption has been taken place over the solid surfaceThe spectra of TMAB indicate that the disappearance oC-C, C-O and N-H bands completely while that N-C shifts

to higher frequencies. This again proves the adsorptionover solid surface through C-C, C-O and N-H groups.

Conclusions

1. Tetra methyl ammonium bromide (TMAB) is veryeffective corrosion inhibitor of mild steel in acidic mediumparticularly at 298K and at higher concentrations.2. The inhibition efficiency increases with the increase inconcentrations, whereas its inhibition efficiencies almos


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Dubey et al. 95

Figure 9.Infra-red spectra of tetra methyl ammonium bromide (TMAB) adsorbed on silica gel.

Table 3.Infra-red spectroscopic data of TMAB.

Inhibitor C-H (cm-1) C-C (cm

-1) C-O (cm

-1) C-OH (cm

-1) N-C (cm

-1) N-H (cm

-1) C=C (cm

-1) N-H deformation (cm

-1)

TMAB 3013.90 1488.33 948.84 - 3436.21 1637 - -TMAB ads 2919.52 - - - 3435.42 - - -

remaining same with increase temperature.3. This is a mixed type inhibitor.4. It mainly acts by blocking the active sites on thecathodic and anodic regions.

REFERENCES

Abd El-Kader JM, El-Warraky AA, Abd El-aziz AM, (1998). Corrosioninhibition of mild steel by sodium tungstate in neutral solution Part 1:Behaviour in distilled water. Bri. Corros. J. 33:2-139.

Bentiss F, Lagrenee M, Traisnel M, Hornez JC (1999).The corrosioninhibition of mild steel in acidic media by a new triazole derivative.Corros. Sci. 41:789.

Bockris JOM, Drazic D (1962). The kinetics of deposition anddissolution of iron: Effect of alloying impurities. Electrochemica Acta7:293.

Chetouani A, Hammouti B, Aouniti A, Benchat N, Benhadda T (2002).New synthesised pyridazine derivatives as effective inhibitors for thecorrosion of pure iron in HCl medium. Progress Org. Coatings45:373.

Elkadi L, Mernari B, Traisnel M, Bentiss F, Lagrenee M (2000). Theinhibition action of 3,6-bis(2-methoxyphenyl)-1,2-dihydro-1,2,4,5tetrazine on the corrosion of mild steel in acidic media. Corros. Sci42:703.

Fouda A, Moussa M, Taha P, Neanaa EL (1986) The role of somethiosemicarbazide derivatives in the corrosion inhibition of aluminiumin hydrochloric acid. Corros. Sci. 26:719.

MacCafferty E, Hackerman N (1973). Kinetics of Iron Corrosion inConcentrated Acidic Chloride Solutions. J. Electrochem. Soc120(6):775-777.

Putilova N, Balezin SA, Barannik VP (1960). Metallic Corrosion

Inhibitors. Pergaman Press, NY. p. 31.Schweinsberg D, George G, Nanayakkara A, Steiner D (1988). Theprotective action of epoxy resins and curing agents - Inhibitive effectson the aqueous acid corrosion of iron and steel. Corros. Sci28(55):33-42.

Tauhami F, Aouniti A, Abed Y, Hammouti B, Kertit S, Ramdani AElkacemi K (2000). Corrosion inhibition of armco iron in 1 M HCmedia by new bipyrazolic derivatives. Corros. Sci. 42:929.

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Corrosion Inhibition Effect of Tetra Methyl Ammonium Bromide (TMAB) in Acidic Media