Research Article A Study of N,N-Diethylammonium ...downloads.hindawi.com/journals/ijc/2016/1907634.pdf · steel in .M HCl with mgL 1 EAPP. EAPP, which blocks the carbon steel surface

Research ArticleA Study of NN-DiethylammoniumOO1015840-Di(p-methoxyphenyl)dithiophosphate as New CorrosionInhibitor for Carbon Steel in Hydrochloric Acid Solution

Chuan Lai123 Bin Xie23 Changlu Liu1 Wan Gou1

Lvshan Zhou1 Xiulan Su1 and Like Zou23

1School of Chemistry and Chemical Engineering Sichuan University of Arts and Science Dazhou 635000 China2Institute of Functional Materials Sichuan University of Science and Engineering Zigong 643000 China3Material Corrosion and Protection Key Laboratory of Sichuan Province Sichuan University of Science and EngineeringZigong 643000 China

Correspondence should be addressed to Bin Xie xiebinsuse163com

Received 21 September 2015 Revised 19 January 2016 Accepted 20 January 2016

Academic Editor Flavio Deflorian

Copyright copy 2016 Chuan Lai et al This is an open access article distributed under the Creative Commons Attribution Licensewhich permits unrestricted use distribution and reproduction in any medium provided the original work is properly cited

NN-Diethylammonium OO1015840-di(p-methoxyphenyl)dithiophosphate (EAPP) as a new corrosion inhibitor was synthesized in thepresentworkThe corrosion inhibition of EAPP in hydrochloric acid for carbon steel was evaluated by potentiodynamic polarizationmeasurements electrochemical impedance spectroscopy weight lossmeasurements and scanning electronmicroscopyThe resultsindicate that the EAPP is mixed type inhibitor and the adsorption of EAPP on carbon steel surface obeys Langmuir isothermIn addition the inhibition efficiency increases with increasing the concentration of inhibitor and decreases with increasing thehydrochloric acid concentration temperature and storage time

1 Introduction

Acid solutions are often used in industry for cleaningchemical decaling and pickling of metals [1 2] Duringthose processes as the existence of undesirable and extensiveattack for metals as an important metal in different acidsolutions the application of corrosion inhibitors for pre-venting corrosion phenomena seems to be more and moreimportant [3 4] Using inhibitor is one of the most practicalmethods for protection against corrosion especially in acidsolution to prevent metals dissolution [5 6] Comparedwith other existing corrosion protection technologies themethod of using corrosion inhibitor has some advantagessuch as no special equipment required low cost and easyoperation

During the past decade many inhibitors have beenstudied in different media Most of the effective corrosioninhibitors are organic compounds containing electronegativeatoms (such as nitrogen atoms phosphorus atoms sulfur

atoms and oxygen atoms) the unsaturated bonds (such asdouble bonds or triple bonds) and the plane conjugated sys-tems including all kinds of aromatic cycles [7ndash9] In fact theOO1015840-diaryldithiophosphates contain nitrogen phosphorussulfur and oxygen atoms in their structure which could bepotential inhibitors

As a result in order to develop the new effective corrosioninhibitor the aim of the present work is to investigate thecorrosion inhibition of NN-diethylammonium OO1015840-di(p-methoxyphenyl)dithiophosphate (EAPP) for carbon steel inhydrochloric acid (HCl) solution Firstly the organic com-pound of EAPP was synthesized Meanwhile EAPP acting asthe novel corrosion inhibitor for carbon steel in HCl solutionwere studied using potentiodynamic polarization measure-ments electrochemical impedance spectroscopy weight lossmeasurements and scanning electron microscopy In addi-tion the effects of inhibitor concentration HCl concentra-tion temperature and storage time on inhibition action werefully investigated

Hindawi Publishing CorporationInternational Journal of CorrosionVolume 2016 Article ID 1907634 8 pageshttpdxdoiorg10115520161907634

2 International Journal of Corrosion

O

O

P

SO

O

P

S

SHOH

EAPP

24

OCH3

OCH3

OCH3 OCH3

OCH3

P2S5PhCH3 NH(Et)2

Sminus

CH2CH3

CH2CH3

+NH2+

Figure 1 Synthesis and molecular structure of the investigated inhibitor

Table 1 Chemical composition of experimental carbon steel (inwt)

Element C Si Mn P S FeComposition 016 027 042 lt0014 lt0011 Bal

2 Materials and Methods

21 Materials In this work phosphorus pentasulphide(P2S5) p-methoxyphenol (p-CH

3OPhOH) diethylamine

(NHEt2) toluene (PhCH

3) hydrochloric acid (37 HCl)

and acetone (CH3COCH

3) were purchased from Sinopharm

Chemical Reagent Co Ltd All the reagents were commer-cially available and used without further purification Thestandard samples (50mm times 20mm times 5mm) and workingelectrode were prepared by carbon steel whose chemicalcomposition is given in Table 1 Meanwhile CHI 660Delectrochemical workstation (China) was used for electro-chemical measurements

The test solutions of HCl solution were prepared byanalytical grade hydrochloric acid and distilled water Duringthe electrochemical and weight loss measurements the tem-perature of test solutionwas controlled by awater thermostatand all experiments were open to the air and carried outunder static conditions

22 Synthesis of Inhibitor NN-Diethylammonium OO1015840-di(p-methoxyphenyl)dithiophosphate (EAPP) acting as thenew corrosion inhibitor was synthesized according to thesynthetic procedures shown in Figure 1 which is preparedby reaction of phosphorus pentasulphide p-methoxyphenolwith diethylamine in toluene as the solvent based on themethod described in our previous works [10ndash12]

23 Electrochemical Measurements The electrochemicalmeasurements were done by conventional three-electrodesystem consisting of carbon steel working electrode with anexposed area of 0785 cm2 a graphite electrode as counterelectrode and saturated calomel electrode (SCE) as referenceAll potentials in this work were referred to the SCE Theworking electrode was immersed in test solution at opencircuit potential (OCP) for 30min to be sufficient to attain astable state before measurement

The potential sweep rate for potentiodynamic polariza-tion (Tafel) curves was 0166mV sminus1 Corrosion current den-sity (119894corr) was determined from the intercept of extrapolatedcathodic and anodic Tafel lines at the corrosion potential(119864corr) The inhibition efficiency (IETafel) was calculated fromthe following equation [13 14]

IETafel () =119894corr minus 119894corr(inh)

119894corrtimes 100 (1)

where 119894corr and 119894corr(inh) are the corrosion current densityvalues of carbon steel inHCl solutionwithout andwith EAPPrespectively

The electrochemical impedance spectroscopy (EIS) mea-surements were performed in frequency range of 100 kHz to10mHz using a sinusoidal AC perturbation with amplitudeof 10mV EIS parameters were fitted by using ZSimpWinsoftware Charge transfer resistance (119877ct) was obtained fromthe diameter of the semicircle of the Nyquist plot Theinhibition efficiency (IEEIS) derived from EIS was calculatedusing the following equation

IEEIS () =119877ct minus 119877

0

ct119877cttimes 100 (2)

where 119877ct and 1198770

ct are the values of charge transfer resistanceobserved in the presence and absence of inhibitor

In this paper the storage time was defined as the timeinterval from the time of addition EAPP in HCl solutionto the time of using the test solution for electrochemicalmeasurements

24 Weight Loss Measurements Before weight loss mea-surements all of the standard carbon steel samples weremechanically abraded with emery paper up to 1200 grit thenrinsed with distilled water degreased in acetone and driedat room temperature The finely polished and dried carbonsteel samples were weighed on a digital balance with 1mgsensitivity and immersed in HCl solution in the absenceand presence of EAPP at various temperatures for 12 h Afterimmersing the tests samples were rinsed with distilled watercleaned with acetone dried and reweighed The weight losswas calculated as the difference in weight of the sample beforeand after immersion in test solutions

In all the above measurements at least three closerresults were considered and their average values have been

International Journal of Corrosion 3

0 5 10 15 20 25 30minus052

minus050

minus048

minus046

Time (min)

EO

CP(V

ver

sus S

CE)

05M HCl05M HCl + EAPP (160mg Lminus1)

Figure 2 Open circuit potential-time curves for carbon steel in05MHCl in the absence and presence of 160mg Lminus1 EAPP at 300K

reported The corrosion rate (V gmminus2 hminus1) and inhibitionefficiency (IEWeight loss) were calculated from (3) and (4) [1516] respectively

V =119898i minus 119898ii119878119905

=Δ119898

119878119905

(3)

IEWeight loss () =V0minus VV0

times 100 (4)

where119898i and119898ii are the mass of the sample before and aftercorrosion Δ119898 is the weight loss of the sample before andafter corrosion 119878 is the total surface area of the sample 119905is the immersion time and V

0and V are corrosion rate of

the carbon steel sample in HCl solution without and withdifferent concentration of EAPP

25 Scanning ElectronMicroscopy The surfacemorphologiesof carbon steel samples before and after immersion in 05MHCl at 300K in the absence and presence of 160mg Lminus1 EAPPfor 2 h were examined by scanning electron microscopy(SEM Tescan Vega III)

3 Results and Discussion

31 Electrochemical Measurements

311 Open Circuit Potential Curves Figure 2 shows thevariation of open circuit potential (119864OCP) of carbon steelworking electrode with immersion time (119905) in 05M HClsolution in absence and presence of 160mg Lminus1 EAPP at300K The initial potential is moved positive value withtime and gradually remains steady value Meanwhile it canbe observed that after 20min immersion only negligiblechanges in the 119864OCP are measured Therefore the steady-state was achieved after 30min for electrochemical tests The119864OCP value at 30min in blank solution (05M HCl without

Table 2The polarization parameters and corresponding inhibitionefficiency for carbon steel in 05M HCl in the absence and presenceof different concentrations of EAPP at 300K

119862 (mg Lminus1) 119864corr (mV) 119894corr (120583Acmminus2) IETafel ()0 minus524 30854 mdash80 minus521 7022 7724100 minus504 3817 8763120 minus493 3246 8948160 minus490 2082 9325

minus07 minus06 minus05 minus04 minus03minus7

minus6

minus5

minus4

minus3

minus2

logI

(A cm

minus2)

0mg Lminus180mg Lminus1100mg Lminus1

120mg Lminus1

160mg Lminus1

E versus SCE (V)

Figure 3 Potentiodynamic polarization curves at 300K for carbonsteel in 05M HCl in the absence and presence of different concen-trations of EAPP

inhibitor) is 04852V (versus SCE)The steady-state potentialmoves positive after adding inhibitor to 05M HCl solutionwhich indicates that the corrosion of carbon steel is retardedby addition of EAPP in HCl solution

312 Potentiodynamic Polarization Measurements

(1) Effect of EAPP Concentration At 300K the potentio-dynamic polarization curves of carbon steel in 05M HClin the absence and presence of different concentrations ofEAPP are shown in Figure 3 Meanwhile the corrosionpotential 119864corr (mV versus SCE) corrosion current density119894corr (120583A cmminus2) and inhibition efficiency (IETafel) are given inTable 2 The inhibition efficiency was calculated by (1)

From Figure 3 and Table 2 both the anodic and cathodiccurves shift to lower current densities which indicate thatthe addition of EAPP can reduce the carbon steel anodicdissolution and also retard the hydrogen ions reductionThe inhibition effect enhances with the increase in EAPPconcentration resulting from the adsorption of EAPP on thecarbon steel electrode surface One possible mechanism isthe adsorption of EAPP on carbon steel surface through theelectron pair of heteroatoms (sulfur and oxygen atoms) the120587 electron of benzene rings in the molecular structure of


300 305 310 315 320 325

20

40

60

80

100

Temperature (K)

Inhi

bitio

n effi

cien

cyTa

fel(

)

Figure 4 Relationships between inhibition efficiency and temper-ature from potentiodynamic polarization measurements for carbonsteel in 05M HCl with 160mg Lminus1 EAPP

EAPP which blocks the carbon steel surface and reduces thecorrosive attraction of carbon steel in HCl media

Clearly the corrosion current density decreases consid-erably in the presence of EAPP comparing with that in theabsence of EAPP and decreases with the EAPP concentra-tion increasing Correspondingly the inhibition efficiencyincreases with the EAPP concentration due to the increasein the blocked fraction of the carbon steel electrode surfaceby adsorption The inhibition efficiency of 160mg Lminus1 EAPPreaches up to 9325 which presents that the EAPP is a goodinhibitor for carbon steel in 05M HCl

In addition it can classify an inhibitor as cathodic oranodic type if the displacement in corrosion potential is morethan 85mV with respect to corrosion potential of the blank[17 18] From Table 2 it can be found that the corrosionpotentials shift slightly in the positive or negative directionAll corrosion potentials of carbon steel in 05MHCl at 300Kshift less than 85mV (versus SCE) and it can be interpretedthat EAPP act as mixed type inhibitor acting on both thehydrogen evolution reaction and carbon steel dissolution

(2) Effect of Temperature Temperature is an important factorthat influences the corrosion rate of carbon steel in HClsolution and modifies the adsorption of inhibitor on carbonsteel surface In order to study the effect of temperature onthe inhibition characteristics experiments were conducted at300K to 323K

The effect of temperature on inhibition efficiency bypotentiodynamic polarization measurements is shown inFigure 4 Clearly inhibition efficiencies decrease with theexperimental temperature which can be attributed to thefact that the higher temperatures might cause desorption ofinhibitor molecule from carbon steel surface With increasein the temperature from 300K to 323K the inhibitionefficiency has dropped from 9325 to 3332

(3) Effect of HCl Concentration The effect of HCl con-centration on the inhibition efficiency of EAPP with the

00 05 10 15 2080

85

90

95

100

Inhi

bitio

n effi

cien

cyTa

fel(

)

HCl concentration (mol Lminus1)

Figure 5 Relationships between inhibition efficiency and con-centration of HCl with 160mg Lminus1 EAPP from potentiodynamicpolarization measurements for carbon steel at 300K

0 20 40 60 80 100 1200

20

40

60

80

100

Storage time (h)

Inhi

bitio

n effi

cien

cyTa

fel(

)

Figure 6 Relationships between inhibition efficiency and storagetime from potentiodynamic polarization measurements for carbonsteel in 05M HCl with 160mg Lminus1 EAPP

concentration of 160mg Lminus1 for carbon steel at 300K is shownin Figure 5 It can be found that the increase of acid concen-tration resulted in decrease of inhibition efficiency graduallyand the minimum inhibition efficiency in 20M HCl is9092 A similar result has been reported in the literature[19]

(4) Effect of Storage TimeThe effect of storage time on inhibi-tion efficiency of EAPP with the concentration of 160mg Lminus1for carbon steel in 05MHCl at 300K is shown in Figure 6 Ascan be seen from Figure 6 the inhibition efficiency decreaseswith storage time increasing but with addition of EAPPin 05M HCl at 48 hours later the inhibition efficiency is9092 which shows that EAPP still exhibit the excellentcorrosion inhibition for carbon steel in 05M HCl


Table 3 The electrochemical parameters of impedance and corre-sponding corrosion inhibition efficiencies or carbon steel in 05MHCl in the absence and presence of different concentrations of EAPPat 300K

119862 (mg Lminus1) 119877ct (Ω cm2) 119862dl (120583F cm

minus2) IEEIS ()0 2337 4693 mdash80 11323 1417 7724100 21207 939 8763120 25292 664 8948160 42646 438 9325

0 100 200 300 400 5000

50

100

150

200

250

minusZ998400

(Ωcm

2)

Z (Ω cm2)


120mg Lminus1

160mg Lminus1

Figure 7 Nyquist plots for carbon steel in 05MHCl in the absenceand presence of different concentrations of EAPP at 300K

313 Electrochemical Impedance Spectroscopy Figure 7shows the Nyquist diagrams for carbon steel in 05M HClwith different concentrations of EAPP at 300K The doublelayer capacitance (119862dl) charge transfer resistance (119877ct) andinhibition efficiency (IEEIS) obtained fromEISmeasurementsare presented in Table 3 It is found that all Nyquist plotsshow a single capacitive loop in both uninhibited andinhibited solutions which is attributed to the charge transferof corrosion process The impedance spectra show that thesingle semicircle and the diameter of semicircle increasewith the concentration of the inhibitors From Table 3 it isrevealed that the 119877ct increased and the 119862dl values decreasedwith the concentration of inhibitor increasing The increaseof 119877ct can be attributed to the formation of protective filmon the carbon steelsolution interface The decrease of 119862dlmay be due to the decrease of the local dielectric constantor the increase of the thickness of the electrical double layerindicating that the inhibitors adsorbed on the carbon steelsurface The best corrosion inhibition efficiency recorded byEIS is 9325 for carbon steel in 05M HCl with 160mg Lminus1EAPP which confirms that EAPP can act as good inhibitorsfor carbon steel in 05M HCl The result obtained from

Table 4The corrosion rate and inhibitor efficiency for carbon steelin 05MHCl in the absence and presence of different concentrationsof EAPP at 300K from weight loss measurements

119862 (mg Lminus1) V (gmminus2 hminus1) IEWeight loss ()0 4598 mdash40 2028 559080 1086 7638100 0729 8415120 0446 9030160 0233 9493

EIS is in good agreement with the results obtained frompotentiodynamic polarization measurements

32 Weight Loss Measurements

321 Effect of EAPP Concentration The inhibition efficiency(IEWeight loss) of different concentrations of EAPP for carbonsteel in 05M HCl at 300K is listed in Table 4 Clearlyinhibition efficiency increases with increase in concentrationof EAPP It should be noted that when the concentrationof EAPP is 160mg Lminus1 the maximum inhibition efficiencyis 9493 which is higher than the inhibition efficiency ofNN-diethylammonium OO1015840-diphenyldithiophosphate forcarbon steel in 5 HCl (8524) [20] and confirms that theEAPP can act as a good corrosion inhibitor for carbon steelin 05M HCl

322 Adsorption Isotherm Theadsorption isotherm can giveimportant information about the interaction of the inhibitorand metal surface Twomain types of interaction can be usedto describe the adsorption behavior of the inhibitor which arephysisorption and chemisorption [21ndash23] These processesdepend on the chemical structure of the inhibitor moleculethe temperature during the experiments the electrochemicalpotential the charge and nature of the metalThe adsorptionof organic inhibitor molecules from the aqueous solution canbe considered as a quasi-substitution process between theorganic compounds in the aqueous phase [Org

(sol)] andwatermolecules associated with the metallic surface [H

2O(ads)] as

represented by the following equilibrium [24 25]

Org(sol) + 119909H2O(ads) 997888rarr Org(ads) + 119909H2O(sol) (5)

where 119909 is the number of water molecules replaced by oneorganic molecule In this situation the adsorption of EAPPwas accompanied by desorption of water molecules from thecarbon steel surface

Fundamental information on the adsorption of inhibitoron metal surface can be provided by adsorption isothermIn order to find the most suitable adsorption isothermfor adsorption of EAPP on carbon steel surface variousisotherms including Langmuir Temkin Frumkin and Flory-Huggins adsorption isotherms [26 27] are employed to fit theexperimental data fromweight lossmeasurements It is found


40 60 80 100 120 140 16060

80

100

120

140

160

180

y = 3953 + 07978x

R = 099905

C120579

C (mg Lminus1)

Figure 8 Langmuir adsorption isotherm of EAPP on carbon steelin 05M HCl at 300K from weight loss measurements

that the adsorption of EAPP on steel surface obeys Langmuiradsorption isotherm as shown in the following [6 26 27]

119862

120579

=1

119870ads+ 119862 (6)

where 119862 is the concentration of EAPP 119870ads is the adsorptionequilibrium constant and 120579 is the surface coverage Thesurface coverage (120579) for different concentrations of EAPP in05MHCl is obtained according to the following equation byweight loss measurements [9 11 16]

120579 =V0minus VV0

(7)

where V0and V are corrosion rate of the samples in 05MHCl

solution without and with EAPP respectivelyThe plots of 119862120579 versus 119862 yield the straight lines as

shown in Figure 8 The strong correlation (119877 gt 0999)suggests that the adsorption of EAPP on carbon steel surfacein HCl solution obeys the Langmuir adsorption isothermMeanwhile the 119870ads value can be determined from theintercepts of the straight lines and 119870ads is also related tothe standard free energy of adsorption (Δ1198660ads) using thefollowing expression [25 27 28]

119870ads =1

555

exp(minusΔ1198660

ads119877119879

) (8)

where 119877 is gas constant (8314 J Kminus1molminus1) 119879 is absolutetemperature (K) and 555 is the molar concentration of waterin the solution expressed in molarity units (mol Lminus1)

The large values of free energy of adsorption (Δ1198660ads)and its negative sign are usually characteristic of a stronginteraction and a high efficient adsorption In general thevalues of Δ1198660ads around minus20 kJmolminus1 or less negative areassociated with an electrostatic interaction between chargedinhibitor molecules and charged metal surface (physisorp-tion) and those of minus40 kJmolminus1 or more negative involve

(a)

(b)

(c)

Figure 9 SEM micrographs for the carbon steel surface beforecorrosion (a) after immersion in 05MHCl without EAPP (b) andwith 160mg Lminus1 EAPP (c) at 300K for 2 h

charge sharing or transfer of electrons from the inhibitormolecules to the metal surface to form a coordinate typebond (chemisorption) [21ndash23] Based on (8) the value ofΔ1198660

ads for EAPP on carbon steel in HCl solution at differenttemperatures is 3311 kJmolminus1 It indicates that the adsorptionof EAPP on carbon steel surface in 05M HCl is chemicaladsorption

33 Scanning Electron Microscopy Figure 9 shows the scan-ning electron microscopy (SEM) images of carbon steelbefore and after being immersed in 05M HCl without andwith 160mg Lminus1 EAPP at 300K for 2 h which is recorded


in order to see the changes occurring during corrosionprocess in the absence and presence of the inhibitor ofEAPP Figure 9(a) shows the surface morphology of thesample before immersion in 05M HCl which mostly seemssmooth with only some nicks However as can be seen fromFigure 9(b) the sample treated with uninhibited solution(05M HCl without EAPP) is strongly corroded and thesurface becomes rough and porous which reveal that thecarbon steel surface is highly corroded and damaged in blanksolution (05M HCl without EAPP) In contrast it can beseen from Figure 9(c) that in the presence of 160mg Lminus1EAPP the steel surface is much less damaged which furtherconfirms the inhibition action and adsorption of EAPP oncarbon steel surface This SEM result is in good agreementwith that obtained from weight loss and potentiodynamicpolarization measurements

4 Conclusions

(1) The inhibition efficiency of NN-diethylammoniumOO1015840-di(p-methoxyphenyl)dithiophosphate (EAPP)for carbon steel in HCl solution increases withincreasing concentration of EAPP and decreases withan increase of temperature HCl concentration andstorage time

(2) The corrosion current density significantly decreasesand corrosion potential slightly changes with theaddition of EAPP in HCl solution and the synthe-sized inhibitor of EAPP is mixed type inhibitor

(3) The adsorption of EAPP on the carbon steel surface ischemical adsorption and obeys Langmuir isotherm

Conflict of Interests

The authors declare that there is no conflict of interestsregarding the publication of this paper

Acknowledgments

This project is supported financially by the Opening Projectsof Key Laboratory of Material Corrosion and Protection ofSichuan Province (nos 2015CL09 2012CL12 and 2011CL03)the Program of Education Department of Sichuan Province(nos 16ZA0358 and 13CZ0019) the Projects of SichuanUniversity of Arts and Science (no HGXZ2015002) theProjects of Sichuan University of Science and Engineering(no 2012PY14) and the Opening Project of Key Laboratoryof Green Catalysis of Sichuan Institutes of Higher Education(nos LYJ1306 LZJ14201 and LYJ1503)

References

[1] M Shyamala and P K Kasthuri ldquoThe inhibitory action of theextracts of Adathoda vasica Eclipta alba and Centella asiaticaon the corrosion of mild steel in hydrochloric acid medium acomparative studyrdquo International Journal of Corrosion vol 2012Article ID 852827 13 pages 2012

[2] M A Quraishi A Singh V K Singh D K Yadav and A KSingh ldquoGreen approach to corrosion inhibition of mild steel inhydrochloric acid and sulphuric acid solutions by the extract ofMurraya koenigii leavesrdquoMaterials Chemistry and Physics vol122 no 1 pp 114ndash122 2010

[3] X M Wang H Y Yang and F H Wang ldquoA cationic gemini-surfactant as effective inhibitor for mild steel in HCl solutionsrdquoCorrosion Science vol 52 no 4 pp 1268ndash1276 2010

[4] G Trabanelli ldquoInhibitors An old remedy for a new challengerdquoCorrosion vol 47 no 6 pp 410ndash419 1991

[5] R Solmaz ldquoInvestigation of corrosion inhibition mechanismand stability of Vitamin B1 on mild steel in 05M HCl solutionrdquoCorrosion Science vol 81 pp 75ndash84 2014

[6] X Li S Deng X Xie and H Fu ldquoInhibition effect of bambooleavesrsquo extract on steel and zinc in citric acid solutionrdquoCorrosionScience vol 87 pp 15ndash26 2014

[7] R Fuchs-Godec and G Zerjav ldquoCorrosion resistance of high-level-hydrophobic layers in combination with Vitamin E-(120572-tocopherol) as green inhibitorrdquo Corrosion Science vol 97 pp7ndash16 2015

[8] P Mourya P Singh A K Tewari R B Rastogi and MM Singh ldquoRelationship between structure and inhibitionbehaviour of quinolinium salts for mild steel corrosion experi-mental and theoretical approachrdquoCorrosion Science vol 95 pp71ndash87 2015

[9] D Daoud T Douadi H Hamani S Chafaa andM Al-NoaimildquoCorrosion inhibition of mild steel by two new S-heterocycliccompounds in 1 M HCl experimental and computationalstudyrdquo Corrosion Science vol 94 pp 21ndash37 2015

[10] B Xie C Lai L K Zou et al ldquoAdsorption behavior and inhi-bition of NN-diethylammoniumOO1015840-dicyclohexydithiophos-phate for carbon steel in acid mediumrdquo Advanced MaterialsResearch vol 239ndash242 pp 347ndash351 2011

[11] B Xie S S Zhu Y L Li et al ldquoCorrosion inhibition per-formance of diethylammonium OOrsquo-Di(2-phenylethyl)dithio-phosphate for Q235 steel inHCl solutionrdquo Journal of the ChineseSociety of Corrosion and Protection vol 34 no 4 pp 366ndash3742014

[12] L K Zou C Lai B Xie et al ldquoAdsorption behavior andcorrosion inhibition of EPP for Q235 steel in H

2SO4solutionrdquo

AdvancedMaterials Research vol 287ndash290 pp 2923ndash2926 2011[13] T BGu Z J ChenXH Jiang et al ldquoSynthesis and inhibition of

N-alkyl-2-(4-hydroxybut-2-ynyl) pyridinium bromide for mildsteel in acid solution BoxndashBehnken design optimization andmechanism proberdquo Corrosion Science vol 90 pp 118ndash132 2015

[14] B Xu W Z Yang Y Liu X S Yin W N Gong and YZ Chen ldquoExperimental and theoretical evaluation of twopyridinecarboxaldehyde thiosemicarbazone compounds as cor-rosion inhibitors for mild steel in hydrochloric acid solutionrdquoCorrosion Science vol 78 pp 260ndash268 2014

[15] X H Li S D Deng H Fu and T H Li ldquoAdsorption and inhibi-tion effect of 6-benzylaminopurine on cold rolled steel in 10 MHClrdquo Electrochimica Acta vol 54 no 16 pp 4089ndash4098 2009

[16] A Kosari M H Moayed A Davoodi et al ldquoElectrochemicaland quantum chemical assessment of two organic compoundsfrom pyridine derivatives as corrosion inhibitors for mild steelin HCl solution under stagnant condition and hydrodynamicflowrdquo Corrosion Science vol 78 pp 138ndash150 2014

[17] M J Bahrami S M A Hosseini and P Pilvar ldquoExperi-mental and theoretical investigation of organic compounds asinhibitors for mild steel corrosion in sulfuric acid mediumrdquoCorrosion Science vol 52 no 9 pp 2793ndash2803 2010


[18] E S Ferreira C Giacomelli F C Giacomelli and A SpinellildquoEvaluation of the inhibitor effect of L-ascorbic acid on thecorrosion of mild steelrdquo Materials Chemistry and Physics vol83 no 1 pp 129ndash134 2004

[19] XH Li X G Xie S D Deng andG B Du ldquoInhibition effect oftwo mercaptopyrimidine derivatives on cold rolled steel in HClsolutionrdquo Corrosion Science vol 92 pp 136ndash147 2015

[20] B Xie C Lai L K Zou et al ldquoSynthesis of OO1015840-diphenyldi-thiophosphate-NN-diethylammonium and its corrosion inhi-bition performancerdquoMaterials Protection vol 44 no 12 pp 63ndash66 2011

[21] A Yurt G Bereket A Kivrak A Balaban and B Erk ldquoEffect ofschiff bases containing pyridyl group as corrosion inhibitors forlow carbon steel in 01MHClrdquo Journal of Applied Electrochemis-try vol 35 no 10 pp 1025ndash1032 2005

[22] V R Saliyan and A V Adhikari ldquoQuinolin-5-ylmethylene-3-[8-(trifluoromethyl)quinolin-4-yl]thiopropanohydrazide asan effective inhibitor of mild steel corrosion in HCl solutionrdquoCorrosion Science vol 50 no 1 pp 55ndash61 2008

[23] AM Fekry andR RMohamed ldquoAcetyl thiourea chitosan as aneco-friendly inhibitor for mild steel in sulphuric acid mediumrdquoElectrochimica Acta vol 55 no 6 pp 1933ndash1939 2010

[24] N A Negm N G Kandile E A Badr and M A MohammedldquoGravimetric and electrochemical evaluation of environmen-tally friendly nonionic corrosion inhibitors for carbon steel in1M HClrdquo Corrosion Science vol 65 pp 94ndash103 2012

[25] S K Shukla and M A Quraishi ldquoCefotaxime sodium a newand efficient corrosion inhibitor for mild steel in hydrochloricacid solutionrdquo Corrosion Science vol 51 no 5 pp 1007ndash10112009

[26] M A Hegazy A S El-Tabei A H Bedair andM A Sadeq ldquoAninvestigation of three novel nonionic surfactants as corrosioninhibitor for carbon steel in 05M H

2SO4rdquo Corrosion Science

vol 54 no 1 pp 219ndash230 2012[27] X Li S Deng and H Fu ldquoInhibition of the corrosion of steel

in HCl H2SO4solutions by bamboo leaf extractrdquo Corrosion

Science vol 62 pp 163ndash175 2012[28] S A Abd El-Maksoud ldquoStudies on the effect of pyra-

nocoumarin derivatives on the corrosion of iron in 05 MHClrdquoCorrosion Science vol 44 no 4 pp 803ndash813 2002

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Journal ofNanomaterials


O

O

P

SO

O

P

S

SHOH

EAPP

24

OCH3

OCH3

OCH3 OCH3

OCH3

P2S5PhCH3 NH(Et)2

Sminus

CH2CH3

CH2CH3

+NH2+

Figure 1 Synthesis and molecular structure of the investigated inhibitor

Table 1 Chemical composition of experimental carbon steel (inwt)

Element C Si Mn P S FeComposition 016 027 042 lt0014 lt0011 Bal

2 Materials and Methods

21 Materials In this work phosphorus pentasulphide(P2S5) p-methoxyphenol (p-CH

3OPhOH) diethylamine

(NHEt2) toluene (PhCH

3) hydrochloric acid (37 HCl)

and acetone (CH3COCH

3) were purchased from Sinopharm

Chemical Reagent Co Ltd All the reagents were commer-cially available and used without further purification Thestandard samples (50mm times 20mm times 5mm) and workingelectrode were prepared by carbon steel whose chemicalcomposition is given in Table 1 Meanwhile CHI 660Delectrochemical workstation (China) was used for electro-chemical measurements

The test solutions of HCl solution were prepared byanalytical grade hydrochloric acid and distilled water Duringthe electrochemical and weight loss measurements the tem-perature of test solutionwas controlled by awater thermostatand all experiments were open to the air and carried outunder static conditions

22 Synthesis of Inhibitor NN-Diethylammonium OO1015840-di(p-methoxyphenyl)dithiophosphate (EAPP) acting as thenew corrosion inhibitor was synthesized according to thesynthetic procedures shown in Figure 1 which is preparedby reaction of phosphorus pentasulphide p-methoxyphenolwith diethylamine in toluene as the solvent based on themethod described in our previous works [10ndash12]

23 Electrochemical Measurements The electrochemicalmeasurements were done by conventional three-electrodesystem consisting of carbon steel working electrode with anexposed area of 0785 cm2 a graphite electrode as counterelectrode and saturated calomel electrode (SCE) as referenceAll potentials in this work were referred to the SCE Theworking electrode was immersed in test solution at opencircuit potential (OCP) for 30min to be sufficient to attain astable state before measurement

The potential sweep rate for potentiodynamic polariza-tion (Tafel) curves was 0166mV sminus1 Corrosion current den-sity (119894corr) was determined from the intercept of extrapolatedcathodic and anodic Tafel lines at the corrosion potential(119864corr) The inhibition efficiency (IETafel) was calculated fromthe following equation [13 14]

IETafel () =119894corr minus 119894corr(inh)

119894corrtimes 100 (1)

where 119894corr and 119894corr(inh) are the corrosion current densityvalues of carbon steel inHCl solutionwithout andwith EAPPrespectively

The electrochemical impedance spectroscopy (EIS) mea-surements were performed in frequency range of 100 kHz to10mHz using a sinusoidal AC perturbation with amplitudeof 10mV EIS parameters were fitted by using ZSimpWinsoftware Charge transfer resistance (119877ct) was obtained fromthe diameter of the semicircle of the Nyquist plot Theinhibition efficiency (IEEIS) derived from EIS was calculatedusing the following equation

IEEIS () =119877ct minus 119877

0

ct119877cttimes 100 (2)

where 119877ct and 1198770

ct are the values of charge transfer resistanceobserved in the presence and absence of inhibitor

In this paper the storage time was defined as the timeinterval from the time of addition EAPP in HCl solutionto the time of using the test solution for electrochemicalmeasurements

24 Weight Loss Measurements Before weight loss mea-surements all of the standard carbon steel samples weremechanically abraded with emery paper up to 1200 grit thenrinsed with distilled water degreased in acetone and driedat room temperature The finely polished and dried carbonsteel samples were weighed on a digital balance with 1mgsensitivity and immersed in HCl solution in the absenceand presence of EAPP at various temperatures for 12 h Afterimmersing the tests samples were rinsed with distilled watercleaned with acetone dried and reweighed The weight losswas calculated as the difference in weight of the sample beforeand after immersion in test solutions

In all the above measurements at least three closerresults were considered and their average values have been


0 5 10 15 20 25 30minus052

minus050

minus048

minus046

Time (min)

EO

CP(V

ver

sus S

CE)




V =119898i minus 119898ii119878119905

=Δ119898

119878119905

(3)


times 100 (4)











minus6

minus5

minus4

minus3

minus2

logI

(A cm

minus2)


120mg Lminus1

160mg Lminus1

E versus SCE (V)







300 305 310 315 320 325

20

40

60

80

100

Temperature (K)

Inhi

bitio

n effi

cien

cyTa

fel(

)








00 05 10 15 2080

85

90

95

100

Inhi

bitio

n effi

cien

cyTa

fel(

)



0 20 40 60 80 100 1200

20

40

60

80

100

Storage time (h)

Inhi

bitio

n effi

cien

cyTa

fel(

)








0 100 200 300 400 5000

50

100

150

200

250

minusZ998400

(Ωcm

2)

Z (Ω cm2)


120mg Lminus1

160mg Lminus1










2O(ads)] as






40 60 80 100 120 140 16060

80

100

120

140

160

180

y = 3953 + 07978x

R = 099905

C120579

C (mg Lminus1)



119862

120579

=1

119870ads+ 119862 (6)


120579 =V0minus VV0

(7)




119870ads =1

555

exp(minusΔ1198660

ads119877119879

) (8)



(a)

(b)

(c)







4 Conclusions






Acknowledgments


References













2SO4solutionrdquo





























CeramicsJournal of







Biomaterials




Journal of


Journal of





CoatingsJournal of

Advances in








MaterialsJournal of


Nano

materials




0 5 10 15 20 25 30minus052

minus050

minus048

minus046

Time (min)

EO

CP(V

ver

sus S

CE)




V =119898i minus 119898ii119878119905

=Δ119898

119878119905

(3)


times 100 (4)











minus6

minus5

minus4

minus3

minus2

logI

(A cm

minus2)


120mg Lminus1

160mg Lminus1

E versus SCE (V)







300 305 310 315 320 325

20

40

60

80

100

Temperature (K)

Inhi

bitio

n effi

cien

cyTa

fel(

)








00 05 10 15 2080

85

90

95

100

Inhi

bitio

n effi

cien

cyTa

fel(

)



0 20 40 60 80 100 1200

20

40

60

80

100

Storage time (h)

Inhi

bitio

n effi

cien

cyTa

fel(

)








0 100 200 300 400 5000

50

100

150

200

250

minusZ998400

(Ωcm

2)

Z (Ω cm2)


120mg Lminus1

160mg Lminus1










2O(ads)] as






40 60 80 100 120 140 16060

80

100

120

140

160

180

y = 3953 + 07978x

R = 099905

C120579

C (mg Lminus1)



119862

120579

=1

119870ads+ 119862 (6)


120579 =V0minus VV0

(7)




119870ads =1

555

exp(minusΔ1198660

ads119877119879

) (8)



(a)

(b)

(c)







4 Conclusions






Acknowledgments


References













2SO4solutionrdquo





























CeramicsJournal of







Biomaterials




Journal of


Journal of





CoatingsJournal of

Advances in








MaterialsJournal of


Nano

materials




300 305 310 315 320 325

20

40

60

80

100

Temperature (K)

Inhi

bitio

n effi

cien

cyTa

fel(

)








00 05 10 15 2080

85

90

95

100

Inhi

bitio

n effi

cien

cyTa

fel(

)



0 20 40 60 80 100 1200

20

40

60

80

100

Storage time (h)

Inhi

bitio

n effi

cien

cyTa

fel(

)








0 100 200 300 400 5000

50

100

150

200

250

minusZ998400

(Ωcm

2)

Z (Ω cm2)


120mg Lminus1

160mg Lminus1










2O(ads)] as






40 60 80 100 120 140 16060

80

100

120

140

160

180

y = 3953 + 07978x

R = 099905

C120579

C (mg Lminus1)



119862

120579

=1

119870ads+ 119862 (6)


120579 =V0minus VV0

(7)




119870ads =1

555

exp(minusΔ1198660

ads119877119879

) (8)



(a)

(b)

(c)







4 Conclusions






Acknowledgments


References













2SO4solutionrdquo





























CeramicsJournal of







Biomaterials




Journal of


Journal of





CoatingsJournal of

Advances in








MaterialsJournal of


Nano

materials







0 100 200 300 400 5000

50

100

150

200

250

minusZ998400

(Ωcm

2)

Z (Ω cm2)


120mg Lminus1

160mg Lminus1










2O(ads)] as






40 60 80 100 120 140 16060

80

100

120

140

160

180

y = 3953 + 07978x

R = 099905

C120579

C (mg Lminus1)



119862

120579

=1

119870ads+ 119862 (6)


120579 =V0minus VV0

(7)




119870ads =1

555

exp(minusΔ1198660

ads119877119879

) (8)



(a)

(b)

(c)







4 Conclusions






Acknowledgments


References













2SO4solutionrdquo





























CeramicsJournal of







Biomaterials




Journal of


Journal of





CoatingsJournal of

Advances in








MaterialsJournal of


Nano

materials




40 60 80 100 120 140 16060

80

100

120

140

160

180

y = 3953 + 07978x

R = 099905

C120579

C (mg Lminus1)



119862

120579

=1

119870ads+ 119862 (6)


120579 =V0minus VV0

(7)




119870ads =1

555

exp(minusΔ1198660

ads119877119879

) (8)



(a)

(b)

(c)







4 Conclusions






Acknowledgments


References













2SO4solutionrdquo





























CeramicsJournal of







Biomaterials




Journal of


Journal of





CoatingsJournal of

Advances in








MaterialsJournal of


Nano

materials





4 Conclusions






Acknowledgments


References













2SO4solutionrdquo





























CeramicsJournal of







Biomaterials




Journal of


Journal of





CoatingsJournal of

Advances in








MaterialsJournal of


Nano

materials

























CeramicsJournal of







Biomaterials




Journal of


Journal of





CoatingsJournal of

Advances in








MaterialsJournal of


Nano

materials










CeramicsJournal of







Biomaterials




Journal of


Journal of





CoatingsJournal of

Advances in








MaterialsJournal of


Nano

materials



Documents

Research Article A Study of N,N-Diethylammonium ...downloads.hindawi.com/journals/ijc/2016/1907634.pdf · steel in .M HCl with mgL 1 EAPP. EAPP, which blocks the carbon steel surface