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Hindawi Publishing CorporationJournal of ChemistryVolume 2013 Article ID 618684 9 pageshttpdxdoiorg1011552013618684

Research ArticleDevelopment of Ecofriendly Corrosion Inhibitors for Applicationin Acidization of PetroleumOilWell

M Yadav1 Sumit Kumar1 and P N Yadav2

1 Department of Applied Chemistry Indian School of Mines Dhanbad 826004 India2Department of Physics Post Graduate College Ghazipur 233001 India

Correspondence should be addressed to M Yadav yadav_drmahendrayahoocoin

Received 5 June 2012 Revised 25 July 2012 Accepted 30 July 2012

Academic Editor Nick Kalogeropoulos

Copyright copy 2013 M Yadav et alis is an open access article distributed under theCreativeCommonsAttribution License whichpermits unrestricted use distribution and reproduction in any medium provided the original work is properly cited

In the present investigation the protective ability of 1-(2-aminoethyl)-2-octadecylimidazoline (AEODI) and 1-(2-octadecylamidoethyl)-2-octadecylimidazoline (ODAEODI) as corrosion inhibitors for N80 steel in 15 hydrochloric acidhas been studied which may nd application as ecofriendly corrosion inhibitors in acidizing processes in petroleum industryDifferent concentration of synthesized inhibitors AEODI and ODAEODI was added to test solution (15 HCl) and corrosioninhibition of N80 steel was tested by weight loss potentiodynamic polarization and AC impedance measurements Inuenceof temperature (298 to 323K) on the inhibition behaviour was studied Surface studies were performed by using SEM It wasfound that both the inhibitors were effective inhibitors and their inhibition eciency was signicantly increased with increasingtheir concentration Polarization curves revealed that the used inhibitors represent mixed-type inhibitors e adsorption of usedinhibitors led to a reduction in the double-layer capacitance and an increase in the charge transfer resistance e adsorption ofused compounds was found to obey Langmuir isotherm e adsorption of the corrosion inhibitors at the surface of N80 steel isthe root cause of corrosion inhibition

1 Introduction

N80 steel is generally used as main construction materialfor down hole tubular ow lines and transmission pipelinesin petroleum industry e main problem of applying N80steel is its dissolution in acidic solutions e acidization ofpetroleum oil well is one of the important stimulation tech-niques for enhancing oil production It is commonly broughtabout by forcing a solution of 15 to 28 hydrochloricacid into the well to remove plugging in the bore well andstimulate production in petroleum industry To reduce theaggressive attack of the acid on tubing and casing materials(N80 steel) inhibitors are added to the acid solution duringthe acidifying process [1] In the previous work some organicinhibitors have been tested for corrosion inhibition of N80steel in hydrochloric medium [2ndash5] e effective acidizinginhibitors that are usually found in commercial formulationssuffer from drawbacks they are effective only at highconcentrations and they are harmful to the environment dueto their toxicity so it is important to search for new nontoxic

and effective organic corrosion inhibitors for N80 steel-15hydrochloric acid system Imidazoline derivatives because oftheir good solubility high stability and lower toxicity havebeen widely used [6ndash8] e encouraging results obtainedwith imidazoline derivatives have incited us to synthesizesome imidazoline derivatives and extend their use in thecorrosion inhibiting action on N80 steel in HCl solution

us it was considered interesting to synthesize non-toxic imidazoline compounds like 1-(2-aminoethyl)-2-octa-decylimidazoline (AEODI) and 1-(2-octadecylamidoethyl)-2-octadecylimidazoline (ODAEODI) and to assess theirinhibitive properties for oil-well tubular steel (N80) in 15hydrochloric acid

2 Experimental

21 Materials Rectangular steel coupons in size of 60 times20 times 03 cm were cut from the N80 steel casing (suppliedby ONGC) with a small hole asymp2mm diameter at the upperedge of specimen for weight loss studies and the size of

2 Journal of Chemistry

electrode for electrochemical studies was taken as 10 times 10times 03 cm N80 steel sample used for the study was analyzedin MET-CHEM Laboratories Baroda India and found tohave the composition C (031) S (0008) P (0010)Si (019) Mn (092) Cr (020) and Fe the rest ecorrosive solution was 15 HCl obtained by the dilutionof hydrochloric acid (Emerk sp gravity asymp 118) with doubledistilled water

22 Weight Loss Measurements e inhibitor concentrationin weight loss study was in range of 20 to 200 ppm Volume oftest solutionwas 300mLe test couponsweremechanicallypolished with different grades of emery papers cleaned withacetone washed with distilled water and nally dried in dryair before every experiment Aer weighing accurately thespecimens were immersed in 500mL of 15 HCl with andwithout the addition of different concentration of inhibitorsAer 6 hours the coupons were taken out washed driedand weighed accurately High temperature (30ndash50∘C) exper-iments were also carried out for a period of 6 h using watercirculated Ultra thermostat (model NBE Germany) with anaccuracy of plusmn05∘C Duplicate experiments were performedin each and mean value of weight loss was reported ecorrosion inhibition ability of an inhibitor is expressed byweight loss method in terms of inhibitor efficiency and isdetermined by the percentage decrease in corrosion rate aerinhibition test Consider

IE = 10076541007654CR0 minus CR

CR010076701007670 times 100 (1)

where CR0 is corrosion rate in absence of inhibitor and CRcorrosion rate in presence of inhibitor Corrosion rate (CR)for the specimen can be calculated in millimeter penetrationper years (mmpy) with the help of the following equation

Corrosion rate = 876 times Δ119882119882119863119863119863119863119863119863

(2)

whereT is exposure time in hoursΔ119882119882 is weight loss ofmetalcoupons in mg A is area of the test coupons in square inchesand D is density of the steel

23 Electrochemical Polarization Studies e potentiody-namic polarization curves were recorded in absence and inpresence of the inhibitors at different concentrations with theN80 steel (area 1 cm2) asworking electrode using Potentiostat(VoltaLab 10) at 25∘C Experiments were performed withsaturated calomel electrode as reference electrode and plat-inum as counter electrodee potentiodynamic polarizationstudy has been carried out at steady state and at a scanrate of 10mVsec and potential range from minus1000mVto +1000mV From the anodic and cathodic polarization

curves Tafel slopes (120573120573a and 120573120573c) and corrosion current(119868119868corr) were obtained For calculatingIE by electrochemicalpolarization method we use the following formula

IE =1198681198680 minus 119868119868inh

1198681198680times 100 (3)

where 1198681198680 is corrosion current in absence of inhibitor and 119868119868inhis corrosion current in presence of inhibitor

24 AC Impedance Studies AC-impedance studies were car-ried out in a three-electrode cell assembly using computercontrolled VoltaLab 10 electrochemical analyser using N80steel as the working electrode platinum as counter electrodeand saturated calomel as reference electrode e data wereanalysed using Voltamaster 40 sowaree electrochemicalimpedance spectra (EIS) were acquired in the frequencyrange from 10 kHz to 1mHz at the rest potential by applying10mV sine wave AC voltage e charge transfer resistance(119877119877ct) and double-layer capacitance (119862119862dl) were determinedfrom Nyquist plots e inhibition efficiencies were calcu-lated from charge transfer resistance values by using thefollowing formula

IE =119877119877ct(Inh) minus 119877119877ct

119877119877ct(Inh)times 100 (4)

where 119877119877ct is charge transfer resistance in absence of inhibitorand 119877119877ct(Inh) is charge transfer resistance in presence of inhi-bitor

25 SEM Analysis Morphology of the metal surface wasstudiedwith the help of ScanningElectronMicroscopemodelSEM Jeol JSM-5800 SEM micrographs were obtained forpolished metal surface metal surface exposed to 15 HClsolution for 6 hours with and without inhibitorinhibitormixtures

26 Synthesis of Inhibitors e imidazoline derivativesAEODI and ODAEODI were synthesized by the reaction ofoctadecanoic acid with diethylenetriamine in xylene as thesolvent in 1 1 and 1 2 molar ratio respectively [9] esynthesis process was carried out in a three-necked askwith thermometer stirrer and water splitter e reactantwas reuxed at 140∘ndash150∘C until no more water came overfrom the water splitter e water splitter was removed thepressure of the reaction system was adjusted to 1412 kPaand the reaction temperature was raised to 250∘C for another30min e desired product was obtained e purity of theproduct was checked by TLCe yield was found to be 80and 88 respectively Consider

R COOH + H2NCH2CH2NHCH2CH2NH2H2O

RCONHCH2CH2NHCH2CH2NH2xylene 150

∘C 25

minusminus

h

Journal of Chemistry 3

RCONHCH2CH2NHCH2CH2NH2cyclization

250 C 30min

N

NR

CH2CH2NH2

R = C17H35(AEODI)

H2Ominus ∘

2R-COOH + H2NCH2CH2NHCH2CH2NH2RCONHCH2CH2NHCH2CH2NHCOR

RCONHCH2CH2NHCH2CH2NHCOR N

NR

NHCO R

R = C17H35(ODAEODI)

cyclizationCH2CH2NH2

H2O

xylene 150∘C 25

minus

h

250 C 30 minH2Ominus ∘

e pure products were characterized using FTIR spec-troscopy and NMR spectroscopy Physical and spectraldata of synthesized imidazoline derivatives are summarizedbelowAEODI Yield 80 mp 94∘C 1HNMR (CDCl3) 120575120575 333 (m2H) 281ndash271 (m 4H) 216 (t 2H) 159 (q 4H) 126ndash123(m 32H) 086 (t 3H) IR (KBr cmminus1) 1650 (C=N) 1610(N=CndashC) 1550 1450 1360 (CndashNndashC) 2700ndash2900 (ndashCndashH)3430 (NndashH str)ODAEODI Yield 88 mp 98∘C 1HNMR (CDCl3) 120575120575 324(m 2H) 288ndash276 (m 4H) 222 (t 2H) 162 (q 4H)122ndash128 (m 32H) 092 (t 3H) 118ndash124 (m 32H) 086(t3H) IR (KBr cmminus1) 1660 (C=N) 1620 (N=CndashC) 15601430 1340 (CndashNndashC) 2700ndash2900 (ndashCndashH) 3450 (NndashH str)1720 (C=O str)

3 Results and Discussion

31 Weight Loss Tests e percentage inhibition efficiencies(IEs) in presence of 20 50 100 150 and 200 ppm ofAEODI and ODAEODI have been evaluated by weight losstechnique aer 6 h of immersion and at 25∘C e corrosionrate (CR) and inhibition efficiency obtained by weight lossdata are shown in Table 1 It is evident from these valuesthat both the inhibitors are signicantly effective even at lowconcentrations like 20 ppm and there is a linear increase inIE in the whole range of concentrations studied

32 Electrochemical Polarization Studies Electrochemicalpolarization behaviour in presence of 20 100 and 150 ppmof AEODI and ODAEODI for N80 steel in 15 HCl at25∘C is shown in Figures 1 to 2 and various parametersobtained are given in Table 2 e curves in Figures 1 and2 illustrate that the nature of the curve remains almostsame even aer the addition of the inhibitors and also onincreasing the concentration of the inhibitor indicating thatthe inhibitors molecules retard the corrosion process without

changing themechanism of corrosion process in themediumof investigation [10] e anodic and cathodic polarizationcurves shied towards lower current density in presenceof both the inhibitors indicating the mixed nature of theinhibitors e increase in the cathodic and anodic Tafelslopes (120573120573119888119888 and 120573120573119886119886) is related to the decrease in both thecathodic and anodic currents e minor shi in the value ofcorrosion potential (119864119864corr) in presence of both the inhibitorsalso supports the mixed nature of the inhibitors [11]

33 Electrochemical Impedance Spectroscopy (EIS) eimpedance data of N80 steel recorded in presence of 20100 and 150 ppm of the inhibitor ODAEODI in 15 HClsolution at 25∘C as Nyquist plots are shown in Figure 3e equivalent circuit parameters for N80 steel in 15HCl solution at 25∘C in presence of 20 50 and 150 ppmof the inhibitor were calculated by using equivalent circuitdiagram (Figure 4) and this is presented in Table 3 From thedata in Table 3 it is clear that the value of 119877119877ct increases onincreasing the concentration of the inhibitor indicating thatthe corrosion rate decreases in presence of the inhibitor It isalso clear that the value of 119862119862dl decreases on the addition ofinhibitor indicating a decrease in the local dielectric constantandor an increase in the thickness of the electrical doublelayer suggesting that the inhibitor molecules function by theformation of a protective layer at the metal surface [12]

In order to conrm the potentiodynamic results the cor-rosion inhibition efficiency (IEs) in presence of 20 100 and150 ppm concentration of the inhibitor ODAEODI in 15HCl acid at 25∘C was also calculated from the correspondingelectrochemical impedance data and is given in Table 3 ecorrosion inhibition efficiencies calculated from impedancedata are in good agreement with those obtained from elec-trochemical polarization data and weight loss measurement

34 Effect of Temperature and ermodynamic ParametersExperiments were carried out at different temperature (298


ab

cd

minus035

minus04

minus045(volts)

minus05

minus05510

Blank

minus6 10minus5 10minus4 10minus3 10minus2

F 1 Polarization curves for N80 steel in 15HCl containing various concentrations of AEODI at 25∘C

a

bc

d

minus035

minus04

minus045

minus05

minus055

10minus6 10

ODAEOPI

minus5 10minus4 10minus3 10minus2

ODAEOPI

ODAEOPI

F 2 Polarization curves for N80 steel in 15HCl containing various concentrations of OAEOI at 25∘C

to 323K) in presence of 150 ppm of inhibitors It has beenfound that the corrosion rate increases with the increase intemperature for both the inhibitors (Table 4) e corrosionrate of N80 steel in absence of inhibitors increased steeplyfrom 303K to 323K whereas in presence of inhibitors thecorrosion rate increased slowly e inhibition efficiency wasfound to decrease with temperature e results show thatthe inhibition efficiency offered by AEODI and ODAEODIwas 6824 and 7475 respectively at 323Ke corrosionparameters in absence and in presence of inhibitors in thetemperature range from 298 to 323K have been summarizedin Table 4

e apparent activation energy (119864119864119886119886) for dissolution ofN80 steel in 15 HCl was calculated from the slope of plotsby using Arrhenius equation

log 119896119896 119896 119896119864119864119900119900119886119886

2303119877119877119877119877+ log119860119860119860 (5)

where 119896119896 is rate of corrosion 119864119864119900119900119886119886 is the apparent activation

energy 119877119877 is the universal gas constant 119877119877 is absolute tem-perature and 119860119860 is the Arrhenius preexponential factor Byplotting log k against 1T the values of activation energy (119864119864119886119886)have been calculated (119864119864119886119886 119896 119896(Slope) times 2303 times 119877119877) (Figure


1500

1000

500

1000 2000 3000 4000 5000

01 2 3 4

F 3 Nyquist plot for N80 steel in 15 HCl acid containingvarious concentrations of ODAEODI (1) 00 ppm (2) 20 ppm (3)100 ppm and (4)150 ppm at 25∘C

CPE

F 4 Electrochemical equivalent circuit used to t theimpedance measurements that include a solution resistance (119877119877119904119904) aconstant phase element (119862119862dl) and a charge transfer resistance (119877119877ct)

Blank

ODAEODI

AEODI

0

05

1

15

2

29 3 31 32

( )

33 34

minus05

F 5 Arrhenius plot for AEODI and ODAEODI

5) Activation energy for the reaction of N80 steel in 15HCl increases in presence of inhibitors (Table 4)e increasein activation energy 119864119864119886119886 may be due to the adsorption of theinhibitors at the surface of the metal [13]

T 1 Effect of inhibitors concentration on corrosion ofN80 steel

Conc (ppm) ODAEODI AEODICR (mmpy) IE CR (mmpy) IE

0 954 mdash 954 mdash20 310 6751 358 624750 204 7862 247 7411100 119 8753 155 8375150 055 9423 084 9119200 033 9654 075 9214

0

3 31 32 33 34

minus05

minus1

minus15

minus2

minus25

minus3

minus35

ODAEODI

AEODI

( )

F 6 Transition state plot for AEOI and ODAEODI

e values of change of entropy (Δ119878119878ads) and change ofenthalpy (Δ119867119867ads) can be calculated by using the followingformula

119896119896 119896 10076521007652119877119877119877119877119873119873119873

10076681007668 exp10076531007653Δ119878119878lowast

11987711987710076691007669 exp10076531007653

Δ119867119867lowast

11987711987711987711987710076691007669 (6)

where 119896119896 is rate of corrosion 119873 is Plankrsquos constant 119873119873 isAvogadros number Δ119878119878lowast is the entropy of activation andΔ119867119867lowast is the enthalpy of activation A plot of log (119896119896119896119877119877)versus 1T (Figure 6) should give a straight line with aslope of (Δ119867119867ads1198962303119877119877) and an intercept of [log(119877119877119896119873119873119873) 119877Δ119878119878lowast1198962303119877119877119877 from which the values of Δ119878119878lowast and Δ119867119867lowast can becalculated (Table 4)

e negative value of Δ119878119878lowast (Table 4) for both theinhibitors indicates that activated complex in rate-determin-ing step represents an association rather than dissociationstep meaning that a decrease in disorder takes place duringthe course of transition from reactant to the activatedcomplex [14] e negative sign of Δ119867119867lowast indicates thatthe adsorption of inhibitors molecule is an exothermicprocess enerally an exothermic process signies eitherphysisorption or chemisorption or a combination of bothTypically the enthalpy of physisorption process is lower thanthat of 4000 kJmole while the enthalpy of chemisorptionsprocess approaches 100 kJmole [15] In the present study the


ODAEODI

AEODI

3

35

4

45

5

3 31 32 33 34

( )

F 7 Variation of log119870119870equ with 1T for N80 steel in 15HCl in presence of ODAEODI and AEODI

0

l

1

2

ODAEODI

AEODI

minus3

minus05

05

minus25 minus2 minus15

15

0

F 8 Langmuir plots for AEODI and ODAEODI

(a) (b) (c)

F 9 SEM of (a) Polished sample (b) Sample in presence of 15 hydrochloric acid and (c) Sample in presence of 150 ppm of ODAEODI


T 2 Potentiodynamic polarization parameters of the corrosion of N80 steel in 15 HCl in absence and presence of differentconcentrations of ODAEODI and AEODI at 25∘C

Inhibitors Concentration of inhibitors (ppm) Tafel slope119868119868corr (120583120583Asdotcm

minus2) 119864119864corr (mV) IEAnodic 120573120573a Cathodic 120573120573c

Blank 0 109 153 4714 minus468 mdash

ODAEODI20 138 183 1496 minus482 6826100 146 188 648 minus476 8625150 152 195 254 minus474 9461

AEODI20 134 176 1728 minus472 6334100 144 184 841 minus474 8216150 148 192 466 minus479 9011

T 3 Equivalent circuit parameters and inhibition efficiency for N80 steel in 15HCl acid in presence of ODAEODI at 25∘C

Concentration (ppm) 119877119877ct (Ω cm2) 119862119862dl (120583120583 sdot cmminus2) IE

0 180 3435 mdash20 580 2824 6897100 1725 2125 8957150 4380 1836 9589

T 4 Immersion test results of N80 steel in 15 HCL in presence of 150 ppm concentration of inhibitors at different temperature(303Kndash323K)

Inhibitor Temp (K) IE CR (mmpy) Δ119867119867lowast (kJmol) 119864119864119886119886 (kJmol) Δ119866119866ads (kJmol) Δ119878119878lowast Jmole sdotK

Blank

298 mdash 954 mdash303 1209313 1927 minus3564 389 mdash mdash323 3042

ODAEODI

298 9423 055303 8817 143313 8127 361 minus8225 7632 minus6215 minus2735323 7475 768

AEODI


absolute value of the heat of adsorption Δ119867119867119900119900 for AEODI andODAEODI was found minus8225 kJmole and minus9215 kJmole(Table 4) indicating the chemisorption of the inhibitors atthe surface of N80 steel e average value of free energy ofadsorption (Δ119866119866ads) was calculated using the following equa-tion

119870119870equ =1

555exp 10076531007653

minusΔ119866119866ads119877119877119877119877

10076691007669 (7)

where Θ is degree of coverage on metal surface 119862119862 is con-centration of inhibitors in mol Lminus1 119877119877 is molar gas constantand 119877119877 is temperaturee value of 555 in the above equationis the concentration of water in the solution in molelitre

e equilibrium constant (119870119870equ) has been replaced by the fol-lowing equation

10077171007717119870119870equ =120579120579

(1 minus 120579120579) times 11986211986210077331007733 (8)

By plotting log 119870119870equ against 1T the value of minusΔ119866119866ads canbe calculated (Δ119866119866ads = minus2303 times 119877119877 times Slope) from the slopeof the straight line obtained (Figure 7) e standard freeenergy of adsorption (Δ119866119866ads) for AEODI andODAEODI wasfound minus6215 kJmol and minus5824 kJmol (Table 4) respec-tively indicating that the inhibitors were adsorbed on themetal surface by chemisorption [16] e negative values


indicate the spontaneity of the adsorption process and stabi-lity of the adsorbed layer on N80 steel surface

35 Adsorption Isotherms e mechanism of corrosioninhibition may be explained on the basis of adsorptionbehavior e most frequently used adsorption isothermsare Langmuir Temkin and Frumkin e degree of surfacecoverage (Θ) for different concentration of inhibitor in15 hydrochloric acid has been evaluated by weight lossvalues e data were tested graphically by tting to variousisotherms A straight line is obtained on plotting log(120579120579120579120579 120579 120579120579120579against log 119862119862 (Figure 8) suggesting that the adsorption ofthe compound on the surface of N80 steel follows Langmuiradsorption isotherm [17]

36 SEM Study Figures 9(a) 9(b) and 9(c) show themicrophotographs for N80 steel in 15 hydrochloric acidin the absence and presence of 150 ppm of ODAEODI at200x magnication On comparing these micrographs itappears that in the presence of inhibitor the surface of thetest material has improved remarkably with respect to itssmoothness e smoothening of the surface would havebeen caused by the adsorption of inhibitor molecules on itand thus the surface is fully covered

4 Discussion

e protective action of the inhibitors AEODI andODAEODI was considered in the context of their adsorptionon the metal surface In acid solution the inhibitors canexist as protonated species which may be adsorbed throughelectrostatic interaction between the positively chargedinhibitors molecules and the negatively charged metalsurface e adsorption of the unprotonated inhibitorsAEODI and ODAEODI on the metal may occur by theinteraction between the vacant d-orbital of iron atom at thesurface and the lone pair electron of nitrogen atom presentin the inhibitors e mechanism of inhibition of corrosionis believed to be through the formation of a protective lmon the metal surface Further when log(120579120579120579120579 120579 120579120579120579 is plottedagainst log 119862119862 straight line is obtained for both the inhibitors (Figure 8) suggesting that inhibitors adsorption followsLangmuir isotherm e inhibition efficiency of ODAEODIis higher than the AEODI due to its larger size and presenceof more number of active atoms e adsorption is occur-ring through nitrogen of amino group and nitrogen anddelocalized 120587120587-electrons of the imidazoline ringe presenceof 120587120587-electrons of the imidazoline ring and large hydrophobichydrocarbon chain facilitate the adsorption process at thesurface of the metal e lowering of inhibition efficiencywith temperature may be due to higher desorption rate athigher temperature e increase in activation energy in pre-sence of inhibitors is due to the formation of a barrier atthe surface of the steel which prevents the dissolution ofthe metal e negative values of 119866119866ads and Δ119867119867lowast indicatethat the adsorption is spontaneous and exothermic processrespectively

5 Conclusions

Both the inhibitors AEODI and ODAEODI act as efficientcorrosion inhibitors for N80 steel in 15 HCl solutionODAEODI shows appreciably higher efficiency than AEODIdue to the presence of more active centres and its larger sizeas compared to the inhibitor AEODI Both the inhibitors actas mixed inhibitors It is suggested from the results obtainedfrom SEM and Langmuir adsorption isotherm that themechanism of corrosion inhibition is occurring through ad-sorption process EIS measurements show that charge trans-fer resistance (119877119877ct) increases and double layer capacitance(119862119862dl) decreases in presence of inhibitors indicating theadsorption of the inhibitors at the surface of N80 steel

References

[1] T O Allen and A P Roberts Production Operations vol 2Oil amp Gas Consultants International Tulsa Okla USA edition1982

[2] S Vishwanatham and P K Sinha ldquoCorrosion protection ofN80 steel in HCl by condensation products of aniline andphenolrdquo Anti-Corrosion Methods and Materials vol 56 no 3pp 139ndash144 2009

[3] Emranuzaman T Kumar S Vishawanatam and G Udayb-hanu ldquoSynergistic effects of formaldehyde and alcoholic extractof plant leaves for protection ofN80 steel in 15HClrdquoCorrosionEngineering Science and Technology vol 39 pp 327ndash332 2004

[4] M A Quraishi M A Quraishi and H Ali ldquoA study ofsome new acidizing inhibitors on corrosion of N-80 alloy in15 boiling hydrochloric acidrdquo Corrosion vol 58 no 4 pp317ndash321 2002

[5] K DNeemla A Jayaraman R C Saxena A K Agrawal andRKrishna ldquoCorrosion inhibitor studies on oil well tubular steelsin hydrochloric acidrdquo Bulletien of Electrochemistry vol 5 no 4pp 250ndash253 1989

[6] A Edwards C Osborne S Webster et al ldquoMechanistic studiesof the corrosion inhibitor oleic imidazolinerdquo Corrosion Sciencevol 36 no 2 pp 315ndash325 1994

[7] O Olivares-Xometl N V Likhanova R Martiacutenez-Palou andM A Domiacutenguez-Aguilar ldquoElectrochemistry and XPS study ofan imidazoline as corrosion inhibitor of mild steel in an acidicenvironmentrdquoMaterials and Corrosion vol 60 no 1 pp 14ndash212009

[8] A J McMahon ldquoe mechanism of action of an oleic imida-zoline based corrosion inhibitor for oileld userdquo Colloids andSurfaces vol 59 pp 187ndash208 1991

[9] S F Wang T Furuno and Z Cheng ldquoSynthesis of 1-hydroxyethyl-2-alkyl-2-imidazoline and its derivative sulfonateamphoteric surfactant from tall oil fatty acidrdquo Journal of WoodScience vol 49 no 4 pp 371ndash376 2003

[10] R B RastogiMM SinghM Yadav and K Singh ldquoSubstitutedthiobiurets and their molybdenum and tungsten complexesas corrosion inhibitors for mild steel in 10N sulphuric acidrdquoIndian Journal of Engineering andMaterials Sciences vol 10 pp155ndash160 2003

[11] G E Badr ldquoe role of some thiosemicarbazide derivativesas corrosion inhibitors for C-steel in acidic mediardquo CorrosionScience vol 51 no 11 pp 2529ndash2536 2009

[12] A Istiaque P Rajendra and M A Quraisi ldquoAdsorption andinhibitive properties of some new Mannich bases of Isatin


derivatives on corrosion ofmild steel in acidicmediardquoCorrosionScience vol 52 no 4 pp 1472ndash1481 2010

[13] A Popova E Sokolova S Raicheva and M Chritov ldquoAC andDC study of the temperature effect on mild steel corrosionin acid media in the presence of benzimidazole derivativesrdquoCorrosion Science vol 45 no 1 pp 33ndash58 2003

[14] V Ramesh Saliyan and A V Adhikari ldquoInhibition of corrosionof mild steel in acid media by Nprime-benzylidene-3- (quinolin-4-ylthio)propanohydraziderdquo Bulletin of Materials Science vol 31no 4 pp 699ndash711 2008

[15] A Kosari M Momeni R Parvizi et al ldquoeoretical andelectrochemical assessment of inhibitive behavior of somethiophenol derivatives on mild steel in HClrdquo Corrosion Sciencevol 53 no 10 pp 3058ndash3067 2011

[16] Z Tao S Zhang W Li and B Hou ldquoCorrosion inhibition ofmild steel in acidic solution by some oxo-triazole derivativesrdquoCorrosion Science vol 51 no 11 pp 2588ndash2595 2009

[17] M M Singh and R B Rastog ldquoiosemicarbazide phenylisothiocyanate and their condensation product as corrosioninhibitors of copper in aqueous chloride solutionsrdquo MaterialsChemistry and Physics vol 80 no 1 pp 283ndash293 2003

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Spectroscopy


electrode for electrochemical studies was taken as 10 times 10times 03 cm N80 steel sample used for the study was analyzedin MET-CHEM Laboratories Baroda India and found tohave the composition C (031) S (0008) P (0010)Si (019) Mn (092) Cr (020) and Fe the rest ecorrosive solution was 15 HCl obtained by the dilutionof hydrochloric acid (Emerk sp gravity asymp 118) with doubledistilled water

22 Weight Loss Measurements e inhibitor concentrationin weight loss study was in range of 20 to 200 ppm Volume oftest solutionwas 300mLe test couponsweremechanicallypolished with different grades of emery papers cleaned withacetone washed with distilled water and nally dried in dryair before every experiment Aer weighing accurately thespecimens were immersed in 500mL of 15 HCl with andwithout the addition of different concentration of inhibitorsAer 6 hours the coupons were taken out washed driedand weighed accurately High temperature (30ndash50∘C) exper-iments were also carried out for a period of 6 h using watercirculated Ultra thermostat (model NBE Germany) with anaccuracy of plusmn05∘C Duplicate experiments were performedin each and mean value of weight loss was reported ecorrosion inhibition ability of an inhibitor is expressed byweight loss method in terms of inhibitor efficiency and isdetermined by the percentage decrease in corrosion rate aerinhibition test Consider

IE = 10076541007654CR0 minus CR

CR010076701007670 times 100 (1)

where CR0 is corrosion rate in absence of inhibitor and CRcorrosion rate in presence of inhibitor Corrosion rate (CR)for the specimen can be calculated in millimeter penetrationper years (mmpy) with the help of the following equation

Corrosion rate = 876 times Δ119882119882119863119863119863119863119863119863

(2)

whereT is exposure time in hoursΔ119882119882 is weight loss ofmetalcoupons in mg A is area of the test coupons in square inchesand D is density of the steel

23 Electrochemical Polarization Studies e potentiody-namic polarization curves were recorded in absence and inpresence of the inhibitors at different concentrations with theN80 steel (area 1 cm2) asworking electrode using Potentiostat(VoltaLab 10) at 25∘C Experiments were performed withsaturated calomel electrode as reference electrode and plat-inum as counter electrodee potentiodynamic polarizationstudy has been carried out at steady state and at a scanrate of 10mVsec and potential range from minus1000mVto +1000mV From the anodic and cathodic polarization

curves Tafel slopes (120573120573a and 120573120573c) and corrosion current(119868119868corr) were obtained For calculatingIE by electrochemicalpolarization method we use the following formula

IE =1198681198680 minus 119868119868inh

1198681198680times 100 (3)

where 1198681198680 is corrosion current in absence of inhibitor and 119868119868inhis corrosion current in presence of inhibitor

24 AC Impedance Studies AC-impedance studies were car-ried out in a three-electrode cell assembly using computercontrolled VoltaLab 10 electrochemical analyser using N80steel as the working electrode platinum as counter electrodeand saturated calomel as reference electrode e data wereanalysed using Voltamaster 40 sowaree electrochemicalimpedance spectra (EIS) were acquired in the frequencyrange from 10 kHz to 1mHz at the rest potential by applying10mV sine wave AC voltage e charge transfer resistance(119877119877ct) and double-layer capacitance (119862119862dl) were determinedfrom Nyquist plots e inhibition efficiencies were calcu-lated from charge transfer resistance values by using thefollowing formula

IE =119877119877ct(Inh) minus 119877119877ct

119877119877ct(Inh)times 100 (4)

where 119877119877ct is charge transfer resistance in absence of inhibitorand 119877119877ct(Inh) is charge transfer resistance in presence of inhi-bitor

25 SEM Analysis Morphology of the metal surface wasstudiedwith the help of ScanningElectronMicroscopemodelSEM Jeol JSM-5800 SEM micrographs were obtained forpolished metal surface metal surface exposed to 15 HClsolution for 6 hours with and without inhibitorinhibitormixtures

26 Synthesis of Inhibitors e imidazoline derivativesAEODI and ODAEODI were synthesized by the reaction ofoctadecanoic acid with diethylenetriamine in xylene as thesolvent in 1 1 and 1 2 molar ratio respectively [9] esynthesis process was carried out in a three-necked askwith thermometer stirrer and water splitter e reactantwas reuxed at 140∘ndash150∘C until no more water came overfrom the water splitter e water splitter was removed thepressure of the reaction system was adjusted to 1412 kPaand the reaction temperature was raised to 250∘C for another30min e desired product was obtained e purity of theproduct was checked by TLCe yield was found to be 80and 88 respectively Consider

R COOH + H2NCH2CH2NHCH2CH2NH2H2O

RCONHCH2CH2NHCH2CH2NH2xylene 150

∘C 25

minusminus

h



250 C 30min

N

NR

CH2CH2NH2

R = C17H35(AEODI)

H2Ominus ∘



NR

NHCO R

R = C17H35(ODAEODI)


H2O

xylene 150∘C 25

minus

h











ab

cd

minus035

minus04

minus045(volts)

minus05

minus05510

Blank



a

bc

d

minus035

minus04

minus045

minus05

minus055

10minus6 10

ODAEOPI


ODAEOPI

ODAEOPI




log 119896119896 119896 119896119864119864119900119900119886119886

2303119877119877119877119877+ log119860119860119860 (5)




1500

1000

500

1000 2000 3000 4000 5000

01 2 3 4


CPE


Blank

ODAEODI

AEODI

0

05

1

15

2

29 3 31 32

( )

33 34

minus05





0 954 mdash 954 mdash20 310 6751 358 624750 204 7862 247 7411100 119 8753 155 8375150 055 9423 084 9119200 033 9654 075 9214

0

3 31 32 33 34

minus05

minus1

minus15

minus2

minus25

minus3

minus35

ODAEODI

AEODI

( )



119896119896 119896 10076521007652119877119877119877119877119873119873119873

10076681007668 exp10076531007653Δ119878119878lowast

11987711987710076691007669 exp10076531007653

Δ119867119867lowast

11987711987711987711987710076691007669 (6)




ODAEODI

AEODI

3

35

4

45

5

3 31 32 33 34

( )


0

l

1

2

ODAEODI

AEODI

minus3

minus05

05


15

0


(a) (b) (c)











0 180 3435 mdash20 580 2824 6897100 1725 2125 8957150 4380 1836 9589



Blank


ODAEODI


AEODI



119870119870equ =1

555exp 10076531007653

minusΔ119866119866ads119877119877119877119877

10076691007669 (7)



10077171007717119870119870equ =120579120579

(1 minus 120579120579) times 11986211986210077331007733 (8)






4 Discussion


5 Conclusions


References





























ISRN Chromatography






CatalystsJournal of






Advances in

Physical Chemistry








Journal of

Chemistry







Journal of

Volume 2013




Journal of

Spectroscopy



250 C 30min

N

NR

CH2CH2NH2

R = C17H35(AEODI)

H2Ominus ∘



NR

NHCO R

R = C17H35(ODAEODI)


H2O

xylene 150∘C 25

minus

h











ab

cd

minus035

minus04

minus045(volts)

minus05

minus05510

Blank



a

bc

d

minus035

minus04

minus045

minus05

minus055

10minus6 10

ODAEOPI


ODAEOPI

ODAEOPI




log 119896119896 119896 119896119864119864119900119900119886119886

2303119877119877119877119877+ log119860119860119860 (5)




1500

1000

500

1000 2000 3000 4000 5000

01 2 3 4


CPE


Blank

ODAEODI

AEODI

0

05

1

15

2

29 3 31 32

( )

33 34

minus05





0 954 mdash 954 mdash20 310 6751 358 624750 204 7862 247 7411100 119 8753 155 8375150 055 9423 084 9119200 033 9654 075 9214

0

3 31 32 33 34

minus05

minus1

minus15

minus2

minus25

minus3

minus35

ODAEODI

AEODI

( )



119896119896 119896 10076521007652119877119877119877119877119873119873119873

10076681007668 exp10076531007653Δ119878119878lowast

11987711987710076691007669 exp10076531007653

Δ119867119867lowast

11987711987711987711987710076691007669 (6)




ODAEODI

AEODI

3

35

4

45

5

3 31 32 33 34

( )


0

l

1

2

ODAEODI

AEODI

minus3

minus05

05


15

0


(a) (b) (c)











0 180 3435 mdash20 580 2824 6897100 1725 2125 8957150 4380 1836 9589



Blank


ODAEODI


AEODI



119870119870equ =1

555exp 10076531007653

minusΔ119866119866ads119877119877119877119877

10076691007669 (7)



10077171007717119870119870equ =120579120579

(1 minus 120579120579) times 11986211986210077331007733 (8)






4 Discussion


5 Conclusions


References





























ISRN Chromatography






CatalystsJournal of






Advances in

Physical Chemistry








Journal of

Chemistry







Journal of

Volume 2013




Journal of

Spectroscopy


ab

cd

minus035

minus04

minus045(volts)

minus05

minus05510

Blank



a

bc

d

minus035

minus04

minus045

minus05

minus055

10minus6 10

ODAEOPI


ODAEOPI

ODAEOPI




log 119896119896 119896 119896119864119864119900119900119886119886

2303119877119877119877119877+ log119860119860119860 (5)




1500

1000

500

1000 2000 3000 4000 5000

01 2 3 4


CPE


Blank

ODAEODI

AEODI

0

05

1

15

2

29 3 31 32

( )

33 34

minus05





0 954 mdash 954 mdash20 310 6751 358 624750 204 7862 247 7411100 119 8753 155 8375150 055 9423 084 9119200 033 9654 075 9214

0

3 31 32 33 34

minus05

minus1

minus15

minus2

minus25

minus3

minus35

ODAEODI

AEODI

( )



119896119896 119896 10076521007652119877119877119877119877119873119873119873

10076681007668 exp10076531007653Δ119878119878lowast

11987711987710076691007669 exp10076531007653

Δ119867119867lowast

11987711987711987711987710076691007669 (6)




ODAEODI

AEODI

3

35

4

45

5

3 31 32 33 34

( )


0

l

1

2

ODAEODI

AEODI

minus3

minus05

05


15

0


(a) (b) (c)











0 180 3435 mdash20 580 2824 6897100 1725 2125 8957150 4380 1836 9589



Blank


ODAEODI


AEODI



119870119870equ =1

555exp 10076531007653

minusΔ119866119866ads119877119877119877119877

10076691007669 (7)



10077171007717119870119870equ =120579120579

(1 minus 120579120579) times 11986211986210077331007733 (8)






4 Discussion


5 Conclusions


References





























ISRN Chromatography






CatalystsJournal of






Advances in

Physical Chemistry








Journal of

Chemistry







Journal of

Volume 2013




Journal of

Spectroscopy


1500

1000

500

1000 2000 3000 4000 5000

01 2 3 4


CPE


Blank

ODAEODI

AEODI

0

05

1

15

2

29 3 31 32

( )

33 34

minus05





0 954 mdash 954 mdash20 310 6751 358 624750 204 7862 247 7411100 119 8753 155 8375150 055 9423 084 9119200 033 9654 075 9214

0

3 31 32 33 34

minus05

minus1

minus15

minus2

minus25

minus3

minus35

ODAEODI

AEODI

( )



119896119896 119896 10076521007652119877119877119877119877119873119873119873

10076681007668 exp10076531007653Δ119878119878lowast

11987711987710076691007669 exp10076531007653

Δ119867119867lowast

11987711987711987711987710076691007669 (6)




ODAEODI

AEODI

3

35

4

45

5

3 31 32 33 34

( )


0

l

1

2

ODAEODI

AEODI

minus3

minus05

05


15

0


(a) (b) (c)











0 180 3435 mdash20 580 2824 6897100 1725 2125 8957150 4380 1836 9589



Blank


ODAEODI


AEODI



119870119870equ =1

555exp 10076531007653

minusΔ119866119866ads119877119877119877119877

10076691007669 (7)



10077171007717119870119870equ =120579120579

(1 minus 120579120579) times 11986211986210077331007733 (8)






4 Discussion


5 Conclusions


References





























ISRN Chromatography






CatalystsJournal of






Advances in

Physical Chemistry








Journal of

Chemistry







Journal of

Volume 2013




Journal of

Spectroscopy


ODAEODI

AEODI

3

35

4

45

5

3 31 32 33 34

( )


0

l

1

2

ODAEODI

AEODI

minus3

minus05

05


15

0


(a) (b) (c)











0 180 3435 mdash20 580 2824 6897100 1725 2125 8957150 4380 1836 9589



Blank


ODAEODI


AEODI



119870119870equ =1

555exp 10076531007653

minusΔ119866119866ads119877119877119877119877

10076691007669 (7)



10077171007717119870119870equ =120579120579

(1 minus 120579120579) times 11986211986210077331007733 (8)






4 Discussion


5 Conclusions


References





























ISRN Chromatography






CatalystsJournal of






Advances in

Physical Chemistry








Journal of

Chemistry







Journal of

Volume 2013




Journal of

Spectroscopy










0 180 3435 mdash20 580 2824 6897100 1725 2125 8957150 4380 1836 9589



Blank


ODAEODI


AEODI



119870119870equ =1

555exp 10076531007653

minusΔ119866119866ads119877119877119877119877

10076691007669 (7)



10077171007717119870119870equ =120579120579

(1 minus 120579120579) times 11986211986210077331007733 (8)






4 Discussion


5 Conclusions


References





























ISRN Chromatography






CatalystsJournal of






Advances in

Physical Chemistry








Journal of

Chemistry







Journal of

Volume 2013




Journal of

Spectroscopy





4 Discussion


5 Conclusions


References





























ISRN Chromatography






CatalystsJournal of






Advances in

Physical Chemistry








Journal of

Chemistry







Journal of

Volume 2013




Journal of

Spectroscopy

















ISRN Chromatography






CatalystsJournal of






Advances in

Physical Chemistry








Journal of

Chemistry







Journal of

Volume 2013




Journal of

Spectroscopy

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