dithiophosphate Derivatives as Corrosion Inhibitors

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the effective corrosion inhibitors are organic compounds, in their molecular ..... measurement, the corrosion inhibitor can be classified as cathodic or anodic type ...
2017; 1 (2): 122–135

xyz2017; 2017;15: 1 (2): 122–135 OpenJournal Chem., 263–271

Research Article

The First Decade (1964-1972) Research Article

Open Access

Chuan Lai, Xiaogang Guo, Jian Wei, Bin Xie*, Like Zou, Xiaolong Li, Zongxin Chen, Max Musterman, Paul Placeholder Changmao Wang

What Is So Different About Investigation on TwoNeuroenhancement? Compounds of O,O’Was ist so anders am Neuroenhancement? dithiophosphate Derivatives as Corrosion Inhibitors Pharmacological and Mental Self-transformation in Ethic for Q235 Steel in Hydrochloric Acid Solution Comparison Journal xyz 2017; 1 (2): 122–135

The First Decade (1964-1972)

https://doi.org/10.1515/chem-2017-0034 Research Article received August 17, 2017; accepted October 5, 2017.

Pharmakologische und mentale Selbstveränderung im ethischen Vergleich

1 Introduction

https://doi.org/10.1515/xyz-2017-0010

received FebruaryIt9, is 2013; accepted Marchthat 25, 2013; July 12,is 2014 Abstract: In this work, thePaul O,O’-dithiophosphate well known the published use of online inhibitor one of the Max Musterman, Placeholder derivatives of S-4-methylbenzyl-O,O’-di(phenyl) dithiophosphate most practical and simple methods to protect metals Abstract: In the concept of the aesthetic formation of knowledge and its as soon (Inhi-Ph) and S-4-methyl benzyl-O,O’-di(4-bromophenyl) containing alloys application, against corrosion, especially under the as possible and success-oriented insights and profits without the dithiophosphate (Inhi-BrPh) were synthesized and environment cleaning, chemical decaling and reference to theacidic arguments developedfor around 1900. The main investigation also 13 characterized by elemental analysis, FT-IR, 1H, includes pickling in various C and 31the P period [1-3]. past decade, ina its number between the entry fields into force andInthe presentation current version. Their function as part of the literary portrayal narrative NMR. Meanwhile, the corrosion inhibition of Q235 steel of organic compounds have been and reported as technique. corrosion in HCl solution by synthesized inhibitors was Keywords: evaluatedFunction, inhibitor in acid media. As everyone knows transmission, investigation, principal, periodthat most of byPharmacological weight loss and and electrochemical measurements. the effective corrosion inhibitors are organic compounds, Mental Self-transformation in Ethic Measurement results indicate that the two inhibitors in their molecular structure, which often contain the Dedicated to Paul Placeholder Comparison of Pharmakologische Inhi-Ph and Inhi-BrPh und are mixed-type inhibitor, the electronegative atoms including N, S, P and O atoms, mentale Selbstveränderung im inhibition efficiency increase with inhibitor concentration unsaturated bonds and the plane conjugated systems ethischen Vergleich increasing, decrease with HCl concentration and [4-6]. corrosion inhibition of the reported organic 1 Studies andThe Investigations temperature increasing. The adsorption of Inhi-Ph and inhibitors is mainly because of physical, chemical or https://doi.org/10.1515/xyz-2017-0010 main investigation alsoadsorption includes the involving period between entry into forceand and Inhi-BrPh on Q235 steel surface obeys LangmuirThe isotherm, the mixed boththe physisorption received February 9, 2013; accepted March 25, 2013; published online July 12, 2014 the presentation in its current version. Theirfrom function part of the literary porwhich belongs to chemical adsorption. chemisorption resulting theasinteraction of polar trayal and narrative technique. centers and of the inhibitor’s molecule with active sites on Abstract: In the concept of the aesthetic formation of knowledge its as soon metal surface. As athe fact, the O,O’-diaryldithiophosphates Keywords: Dithiophosphate; Inhibitor; Electrochemical; as possible and success-oriented application, insights and profits without can act theBiology, potential inhibitors metals Weight loss; to Langmuir reference the arguments developed around*Max 1900. The main investigation alsoNationaleffective Musterman: Institute ofas Marine Taiwan Ocean University, for 2 Pei-Ning protecting resulting from their molecular structure Road Keelung 20224, Taiwan (R.O.C), e-mail: [email protected] includes the period between the entry into force and the presentation in its current Paul Placeholder:containing of Marine Ocean University, 2 Pei-Ning P, SBiology, and ONational atoms.Taiwan The dialkyldithiophosphates version. Their function as part of the literary portrayal and Institute narrative technique. Road Keelung 20224, Taiwan (R.O.C), e-mail: [email protected] and their derivatives are versatile compounds, which Keywords: Function, transmission, investigation, principal, period Open Access. © ���� Mustermann by De Gruyter. This work is usually can and bePlaceholder, used aspublished the anti-oxidants, insecticides, licensed under the Creative Commons Attribution-NonCommercial-NoDerivatives �.� License. *Corresponding author: Bin Xie: Institute of Functional Materials, flotation reagents and additives to lubricating oils [7-8]. Dedicated to Paul Placeholder Material Corrosion and Protection Key Laboratory of Sichuan Based on our previous works [9-11], the ammonium salts of Province, Sichuan University of Science and Engineering, Zigong O,O’-dialkyldithiophosphoric acid as the ionic compounds 643000, PR China, E-mail: [email protected] acting as the corrosion inhibitors were studied and Chuan Lai, Xiaolong Li, Zongxin Chen, Changmao Wang: School of reported in recent years. However, there are few reports 1 Studies and Investigations Chemistry and Chemical Engineering, Eastern Sichuan Sub-center of National Engineering Research Center for Municipal Wastewater about the covalence compounds of S-4-methylbenzylTreatment and investigation Reuse, Sichuan also University of Artsthe andperiod Science, O,O’(Inhi-Ph) and S-4The main includes between the entrydi(phenyl)dithiophosphate into force and Dazhou 635000, PR China methylbenzyl-O,O’-di(4-bromophenyl)dithiophos-phate the presentation in its current version. Their function as part of the literary porChuan Lai: Institute of Functional Materials, Material Corrosion and trayal and narrativeoftechnique. Protection Key Laboratory Sichuan Province, Sichuan University of (Inhi-BrPh) as the new excellent corrosion inhibitors. Therefore, the aim of the present work is to develop the Science and Engineering, Zigong 643000, PR China Xiaogang Guo: College of Chemistry and Chemical Engineering, new potential effective corrosion inhibitor and evaluate the Yangtze University, Fuling, 408003, PR China of corrosion inhibition. After the covalence *MaxNormal Musterman: Institute of Marine Biology, National Taiwan Oceanperformance University, 2 Pei-Ning JianRoad Wei,Keelung Like Zou:20224, Institute of Functional Material Taiwan (R.O.C), Materials, e-mail: [email protected] compounds of Inhi-Ph and Inhi-BrPh synthesized and Corrosion and Protection Key Laboratory Sichuan Province, Sichuan Paul Placeholder: Institute of Marine of Biology, National Taiwan Oceancharacterized University, 2 Pei-Ning by elemental analysis, FT-IR, 1H, 13C and 31P

What Is So Different About Neuroenhancement? Was ist so anders am Neuroenhancement?

University of Science and Taiwan Engineering, Zigong 643000, PR China Road Keelung 20224, (R.O.C), e-mail: [email protected]

OpenAccess. Access. © © ���� and Placeholder, by De Gruyter. This Open 2017 Mustermann Chuan Lai et al., publishedpublished by De Gruyter Open. Thiswork workis is licensed under the Creative Commons licensed under the Creative Commons Attribution-NonCommercial-NoDerivatives �.� License. Unauthenticated Attribution-NonCommercial-NoDerivatives 4.0 License. Download Date | 12/11/17 1:11 AM

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  Chuan Lai et al.

NMR. The corrosion inhibition of Q235 steel in HCl solution by Inhi-Ph and Inhi-BrPh were evaluated by weight loss and electrochemical measurements.

2 Materials and methods 2.1 Materials

the inhibitors of Inhi-Ph and Inhi-BrPh were synthesized in the following same procedure. Firstly, (4-BrPhO)2PS2NH2Et2 and (PhO)2PS2NH2Et2 (10 mmoL) were dissolved in CH2Cl2 (60 mL) at room temperature, respectively, with that the 4-methylbenzyl chloride (10.2 mmoL) was added in the solution over a period of 30 min, and the mixture was stirred about 12 h. Afterwards, the solvent was removed under vacuum, and the residue was then taken up in 100 mL of H2O/CH2Cl2 solution (1:1 v/v). The organic phase was separated and washed with 6×100 mL of H2O, and dried over Na2SO4. The organic phase was purified by column chromatography (1:l CH2Cl2/hexane) to obtain Inhi-Ph and Inhi-BrPh. After that, the target synthesized compounds were characterized by different technologies including elemental analysis, FT-IR, 1H, 13C and 31P NMR.

In this study, all the chemical reagents and solvents involving toluene, acetone, hydrochloric acid (37%, HCl), phosphorus pentasulphide (P2S5), 4-bromophenyl (4-BrPhOH), phenol (PhOH), dichloromethane (CH2Cl2), 4-methylbenzyl chloride (4-MePhCH2Cl), diethylamine (NHEt2) and sodium sulfate (Na2SO4) were purchased analysis, FT-IR, 11H, 13 C and 31P NMR. analysis, FT-IR, H, 13C and 31P NMR. from Sinopharm Chemical Reagent Co., Ltd, which were commercially available and analytically pure. 2.3 Weight loss measurement 2.3 Weight loss measurement 2.3 Weight loss measurement The target synthesized inhibitors were characterized presentwork, work,the theweight weight loss measurement by elemental analysis (Carlo Erba 1106 instrument, Italy), In present loss measurement waswas usedused to to study th In present work, the weight loss measurement was used to study th 1 FT-IR (Nicolet- 6700 FT-IR spectrometer, USA), NMR ( H, study the corrosion inhibition of Q235 steel in HCl solution 13 Q235bysteel in HCl solution by Inhi-Ph Inhi-BrPh. Before Inhi-Ph and Inhi-BrPh. Beforeand measurement, all of measureme C and 31P, Bruker-500 NMR spectrometer, Germany). Q235 steel in HCl solution by Inhi-Ph and Inhi-BrPh. Before measureme Meanwhile, the electrochemical measurements using to specimens were mechanically abraded with emery paper mechanically abraded with emery paper up to 1200 grit, rinsed with dis up to 1200abraded grit, rinsed distilled degreased in evaluate the performance of corrosion inhibition were mechanically with with emery paper water, up to 1200 grit, rinsed with dis employed by CHI 660D electrochemical workstation acetone, and then dried at room temperature. The finely acetone, and then dried at room temperature. The finely polished and d acetone, and then dried Q235 at room finely on polished and d polished and dried steeltemperature. samples wereThe weighed (China). The working electrode and test specimens in a digital balance with 1 mg sensitivity and immersed in present work were prepared by Q235 steel. Electrochemical were weighed on a digital balance with 1 mg sensitivity and immerse wereHCl weighed onina the digital balance 1 mg solution absence and with presence of sensitivity synthesizedand immerse measurements were conducted by conventional threeabsence and presence of synthesized inhibitors temperatures fo inhibitors at various temperatures for at 12various h. After electrode system consisting of Q235 steel working electrode absence and presence of synthesized inhibitors at various temperatures f with an exposed area in 0.785 cm2, a counter graphite immersing, the tests samples were rinsed with distilled the tests samples were rinsed with dried distilled cleanedThe with acetone, water, cleaned with acetone, andwater, reweighed. electrode and a saturated calomel reference electrode the tests samples were rinsed with distilled water, cleaned with acetone, (SCE). All of specimens with sizes of 5 mm×20 mm×50 mm weight loss was calculated as the difference in weight of weight loss was calculated as the difference in weight of the sample befo theloss sample and as after solutions. were used by weight loss measurement. weight was before calculated theimmersion difference in in test weight of the sample befo In addition, the different concentrations of HCl Based on this method, at least three closer results were test solutions. Based on this method, at least three closer results we test considered, solutions. Based on average this method, least three closer results we and their values at have been reported. solutions as testing solution were prepared by HCl (37%) -2 -1 The values corrosion ratebeen (v, greported. m h ) and and deionized water. During the whole testing process, corresponding average have Thethe corrosion rate (v, g m-2-2 h-1-1 average values have been reported. The corrosion rate (v, temperature of solution was controlled by the water inhibition efficiency (ηW (%)) were obtained by Equation 1 g m h inhibition (ηW (%)) were obtained by Equation 1 and 2 [10,12], thermostat (DF-101S, China), and all the experiments were and 2 efficiency [10,12], respectively. inhibition efficiency (ηW (%)) were obtained by Equation 1 and 2 [10,12] carried out under static conditions and open to the air. � �� ∆� (1) 𝑣 = �11 ���� = ∆�

2.2 Synthesis

𝑣=

�� ��

=

�� �� 𝑣0 �𝑣 𝜂� (%) = 𝑣0�𝑣 × 100% 𝜂� (%) = 𝑣0 × 100% 𝑣0



(2)

In order to prepare the target inhibitors of S-4where m1 and m2 are the mass of the test specimens before and after testi methylbenzyl-O,O’-di(phenyl) dithiophosphate (Inhim2 are mass of the specimens beforeand after testi where m1 and where m1 and m2 are the the mass of the testtest specimens before Ph) and S-4-methylbenzyl-O,O’-di(4-bromophenyl) and after testing, ∆m is average weight loss, S is the total loss, S is the total surface area of the test specimen, t is the immersion tim loss, surface S is thearea totalofsurface of the test specimen, t is time, the immersion tim dithiophosphate (Inhi-BrPh), the starting compounds the testarea specimen, t is the immersion of O,O’-dithiophosphoric acid ammonium salt v0 and v arespecimens corrosion rate of the test specimens corrosion rate of the test corrosion in HCl solution without and with d of the solution test specimens corrosion in HCl solution without and with d ((RO)2PS2NH2Et2) were synthesized by reaction of P2Srate in HCl without and with different concentrations , 5 Inhi-Ph and Inhi-BrPh. of Inhi-Ph and Inhi-BrPh. ROH (R=4-BrPh and Ph) with NHEt2 in toluene based on Inhi-Ph and Inhi-BrPh. reported methods [9,10,11]. After (RO)2PS2NH2Et2 prepared,

2.4 Electrochemical measurements 2.4 Electrochemical measurements Unauthenticated Electrochemical measurements including potentiodynamic polariza Electrochemical measurements including polariza Download Date | 12/11/17 potentiodynamic 1:11 AM

and electrochemical impedance spectroscopy (EIS) were conducted and electrochemical impedance spectroscopy (EIS) were conducted



Investigation on Two Compounds of O,O‘-dithiophosphate Derivatives as Corrosion Inhibitors... 

2.4 Electrochemical measurements

Table 1: Elemental analysis of Inhi-Ph and Inhi-BrPh.

Electrochemical measurements including potentiodynamic Inhibitor Molecular Anal. Calcd Anal. Found formula polarization (Tafel) measurement and electrochemical C(%) H(%) S(%) C(%) H(%) S(%) impedance spectroscopy (EIS) were conducted by Inhi-Ph C H O PS 62.16 4.96 16.59 62.15 4.98 16.56 20 19 2 2 conventional three- electrode system, and all potential in Inhi-BrPh C20H17O2PS2Br2 44.14 3.15 29.36 44.15 3.14 29.35 this study were referred to the saturated calomel electrode C20H17O2PS2Br Inhi-BrPh 44.14 3.15 29.36 44.15 2 (SCE). Before electrochemical measurements, the working electrode was immersed in test solution at open circuit potential (OCP) for 30 min to be sufficient to attain a stable Inhi-BrPh state. The potential sweep rate for Tafel curves was 0.5 mV s-1. Corrosion current density (icorr) was determined from the intercept of extrapolated cathodic and anodic Tafel � ��potential (E ). The corresponding lines at the corrosion ) = ��rr ��rr(���) 𝜂� � (% × corr 100% (3) �� ���rr inhibition efficiency (η (%)) based on Tafel curves were ��rr ��rr(���) Inhi-Ph P ���rr ����rr(���) = × 100% (3) 𝜂� (%)�= × 100%3 [9, 13]: (3) calculated according to Equation ��rr � ��rr

3.14

29.35

Transmittance (%)

𝜂 � ( %)

 265

In Equation ���rr 3, �� Icorr and Icorr(inh) are the corrosion current density of working electrode in HCl ��rr(���) (%) 𝜂 = × 100% (3) (3)corrosioncurrent � In Equation 3, I and are current density electrode in HClin HCl Equation 3, Icorr andcorrIcorr(inh) are the the corrosion densityofofworking working electrode ���rr Icorr(inh) solution without and with different concentrations of Inhi-Ph and Inhi-BrPh. solution without with concentrations Inhi-Ph and Inhi-BrPh. In Equation 3, Iand and Idifferent are the current of working electrode HCl 1500 1000 500 and Icorr(inh) are thecorrosion corrosion currentdensity In Equation 3, different Icorr corr corr(inh) 4000 3500 3000 2500 in2000 ution without and with concentrations ofofInhi-Ph and Inhi-BrPh. density of working electrode in HCl solution without and EISwaswas performed in concentrations frequency range from kHz using to 10aWavenumbers mHz using a )sinusoidal AC (cm EIS performed frequency range from kHzand to100 10 mHz sinusoidal AC solution with in different of100 Inhi-Ph Inhi-BrPh. withwithout differentand concentrations of Inhi-Ph and Inhi-BrPh. EIS was performed in frequency range from 100 kHz to 10 mHz using a sinusoidal AC EIS was performed in frequency range from 100 kHz to 10 Figure 1:fitted Infrared Inhi-Ph and Inhi-BrPh. perturbation amplitude 10 mV. EIS parameters were by using Z-View software. The Figure 1:mHz Infrared spectra of Inhi-Phof and Inhi-BrPh. perturbation with amplitude of 10 mV. EIS 100 parameters were by using Z-View software. The EIS waswith performed in of frequency range from kHzfitted to 10 using a spectra sinusoidal AC mHz using a sinusoidal AC perturbation with amplitude turbation with amplitude of 10 mV. EIS parameters were fitted by using Z-View software. The of transfer 10 mV. EIS parameters wereobtained fitted byfrom usingtheZ-View was diameter ofbytheusing semicircle ofsoftware. the Nyquist charge resistance (Rof ct) 10 perturbation with amplitude mV. EIS parameters were Z-View The of the Nyquist ) was obtained fromfitted the diameter of the semicircle charge transfer resistance (R ct software. The charge transfer resistance (Rct) was obtained presented in Table 1 (elemental analysis), Table 2 and ) was obtained from the diameter of the semicircle rge transfer resistance (R 1 of 13 the 31 ct Figure 1 (FT-IR), Table 3data (the from the diameter of the semicircle of the Nyquist plot. The H,Equation CInhi-Ph and Nyquist P NMR), respectively. Table 2: Infrared spectra ofNyquist and Inhi-BrPh (cm-1). was calculated using the following plot. The corresponding inhibition efficiency (ηE(%)) the diameter of the semicircle of charge transfer resistance (R ct) was obtained from calculated using the following plot.corresponding The corresponding inhibition efficiency (ηE(%)) was inhibition efficiency (ηE(%)) From Table 1, according to the results ofEquation elemental was calculated [11,14] Inhibitor  (=C-H)  (C=C)  ((P)-O-C)  (P-O-(C))  (S-C) asym (PS2) : using the following Equation t. The corresponding inhibition efficiency (ηE(η(%)) was calculated calculated using following plot.using The corresponding inhibition efficiency analysis, the the calculated andEquation observed elemental analysis the following Equation [11,14]: E(%))was [11,14] : data for the synthesized are in good agreement672.3(s) 0 1159.0(s) inhibitors 919.1(s) [11,14] 𝑅�� �𝑅�� 4] : (%) 𝜂 = × 100% (4) 1513.5(s) (4) and fit well the structure of Inhi-Ph and Inhi-BrPh showing : � 𝑅�� Inhi-Ph 3024.8(w) 1182.2(s) 1023.5(s) 898.7(s) 723.0(m) 0 𝑅�� �𝑅�� in 1590.4(s) Figure 2. Meanwhile, the FT-IR, 1H, 13C and 31P NMR 0 𝑅 �𝑅 ( ) 𝜂 % = × 100% (4) �� �� 0 1237.6(m) 1069.9(m) 0 = 𝜂�𝑅𝑅�(%) 𝑅× results further confirmed that the target chemical780.3(s) are values the values of charge transfer where and 𝑅𝑅���� are the of charge transfer resistance of were working electrode in(4) HCl where �� 100% �� �� and ���𝑅 × 100% (4) 𝜂 � ( %) = 907.4(s) the Inhi-Ph and resistance of working electrode in HCl solution without structures are also in good agreement -1

𝑅��

1480.9(s) 1160.8(m) 684.7(s) 0 0 solution and with different of Inhi-Ph and Inhi-BrPh. Inhi-BrPh structureelectrode showing in Figure 2. and𝑅without with different Inhi-Ph and Inhiandand 𝑅 are the values of ofcharge resistance of working HClelectrode where are the concentrations values of transfer charge transfer resistance of working in HCl where 𝑅 934.8(s) �� 𝑅 �� ��concentrations ��

Inhi-BrPh 3039.5(w) 1514.8(w) 1189.6(s) 0 BrPh. and 𝑅�� are the values of charge transfer resistance of working electrode in HCl 827.2(s) 757.4(m) ere 𝑅�� 1010.5(m) Ethical approval: The conducted research is not related to either human or animals use. solution without and with different concentrations of Inhi-Ph and Inhi-BrPh. 1581(w) and 1203.6(s) 773.4(m) approval: The different conductedconcentrations research is not of Inhi-Ph solutionEthical without and with Inhi-BrPh. 1066.6(m) related to either human or animals use. 3.2 Weight loss measurement ution without and withThe different concentrations of Inhi-Ph and Inhi-BrPh. Ethical approval: conducted research w=weak, is not related to either human or animals use. s=strong, m=medium. Ethical approval: The conducted research is not related to either human or animals use. The effect of inhibitors concentration on the corresponding 3 Results andconducted discussionresearch is not related to either ical approval: The human or animals use.

3 Results and discussion

sym

469

51

580

477

534

605

inhibition efficiency (ηW(%)) for Q235 steel in 1.0 M HCl 1 31 loss spectra measurement exhibited in H, 13from C andweight P NMR data of was Inhi-Ph and Inhi-BrPh. Table at 3: 30°C Figure 3. From this figure, it can be found that the inhibition 1 13 31 Inhibitorof target synthesized H NMR CNMR PN 3 Results and discussion In order to confirm the molecular structure corrosion inhibitors, the efficiencies increase with concentration of Inhi-Ph and 3.1 Characterization 3.1 Characterization Results and discussion 2.41 (s, 3H, CH3), 4.30 (dd, J when the 21.25 (SCH2), 38.91of(CH increasing, concentration inhibitor 3), 121.68, 1 Inhi-BrPh 13 31 H,increase C andto P60NMR were employed different technologies including elementalstructure analysis,of FT-IR, -1inhibitors, In order order to confirm confirm the molecular target synthesized corrosion the 3.1 In Characterization mg L to the molecular structure of target , the inhibition efficiency change Inhi-Ph =15.22, 3.96 Hz, 2H, SCH2), 7.17 121.71, 125.77, 129.66, 133.12, 89.38 (t, J= Characterization synthesized corrosion inhibitors, the different technologies slightly with inhibitor concentration further increase. This 1 13 31 -7.44 (m, 14H, 3Ph-H) 137.71, to analyzetechnologies the chemical structural of Inhi-Ph and 31Inhi-BrPh. characterization results were150.66 (Ph-C, MeC6H4) H,isThe C and Psurface NMRcoverage were employed different including elemental FT-IR, 1 analysis, In order to confirm the molecular structure target corrosion inhibitors, the including elemental analysis, FT-IR, due to thesynthesized of the inhibitors on Q235 steel H, 13C and P NMR of 2.38 (s, 3H, CH3), 4.23 (d, J 21.2231(SCH2), 39.26 (CH3), 119.02, 1inhibitors 13 inhibitors, surface increase with concentration increasing. were employed to analyze the chemical structural of In order to confirm the molecular structure of target synthesized corrosion the C andwere P presented Table 1 (elemental analysis), Table and 2 and Figure 1 (FT-IR),Table 3 ( H,results to analyzeinthe chemical structural of Inhi-Ph Inhi-BrPh. The characterization 13 =17.46Hz, SCH12also ), 7.08-7.21 (m,31 129.00,for 129.81, The2H, results show that the123.401,123.44, inhibition efficiency InhiInhi-Phtechnologies and Inhi-BrPh. including The characterization results were different elemental Inhi-BrPh analysis, FT-IR, H, C and P NMR were employed 90.81 (t, J=

3.1 Characterization 3 Results and discussion

1 H 13 31 133.12, 137.86, 149.26, 8H, BrC 7.46-7.48 4H, NMR), respectively. 4), C C 132.65, andemployed P presented in Table 1 (elemental analysis), Table 2 and Figure 16 (FT-IR),Table 3 (1H, 13 H, and 31(m, P NMR were ferent technologies including elemental analysis, FT-IR, MeC H ) 149.34 (C6H4Unauthenticated ) results were 6 4 Inhi-BrPh. The characterization to analyze the chemical structural of Inhi-Ph and From Table 1, according to the results of elemental analysis, the calculated and observed NMR), respectively. Date | were 12/11/17 1:11 AM analyze the chemical structural of Inhi-Ph and Inhi-BrPh. The characterization results s=singlet, d=doublet, t=triplet, q=quartet. Download 1 13 31 presented in Table 1 for (elemental analysis), Tableare2analysis, andgood Figure 1 (FT-IR),Table elemental thetosynthesized inhibitors in agreement andand fit observed well the3 ( H, C and P From analysis Table 1,data according the results of elemental the calculated 1

13

31

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Table 2: Infrared spectra data of Inhi-Ph and Inhi-BrPh (cm-1). Inhibitor

ν (=C-H)

ν (C=C)

ν ((P)-O-C)

ν (P-O-(C))

ν (S-C)

νasym (PS2)

νsym (PS2)

Inhi-Ph

3024.8(w)

1513.5(s) 1590.4(s)

3039.5(w)

1480.9(s) 1514.8(w) 1581(w)

919.1(s) 1023.5(s) 1069.9(m) 907.4(s) 934.8(s) 1010.5(m) 1066.6(m)

898.7(s)

Inhi-BrPh

1159.0(s) 1182.2(s) 1237.6(m) 1160.8(m) 1189.6(s) 1203.6(s)

672.3(s) 723.0(m) 780.3(s) 684.7(s) 757.4(m) 773.4(m)

469.4(m) 512.2(s) 580.7(m) 477.7(m) 534.3(m) 605.1(m)

827.2(s)

w=weak, s=strong, m=medium. Table 3: 1H, 13C and 31P NMR spectra data of Inhi-Ph and Inhi-BrPh. Inhibitor

1

H NMR

13

31

Inhi-Ph

2.41 (s, 3H, CH3), 4.30 (dd, J =15.22, 3.96 Hz, 2H, SCH2), 7.17 -7.44 (m, 14H, 3Ph-H) 2.38 (s, 3H, CH3), 4.23 (d, J =17.46Hz, 2H, SCH2), 7.08-7.21 (m, 8H, BrC6H4), 7.46-7.48 (m, 4H, MeC6H4)

21.25 (SCH2), 38.91 (CH3), 121.68, 121.71, 125.77, 129.66, 133.12, 137.71, 150.66 (Ph-C, MeC6H4) 21.22 (SCH2), 39.26 (CH3), 119.02, 123.401,123.44, 129.00, 129.81, 132.65, 133.12, 137.86, 149.26, 149.34 (C6H4)

89.38 (t, J=15.22 Hz)

Inhi-BrPh

CNMR

PNMR

90.81 (t, J=17.46 Hz)

s=singlet, d=doublet, t=triplet, q=quartet. CH2

Ph higher than the inhibition efficiency for Inhi-BrPh. The difference in corrosion inhibition is due to the bromine S Br O S FigureO 2: Chemical structures of Inhi-Ph and Inhi-BrPh. atom as electron drawing group lead to the decrease in the electron density of benzene rings. The decrease in the Inhi-Ph Inhi-BrPh electron density of benzene rings will weaken the adsorption between benzene rings and Q235 steel surface, and leading Figure 2: Chemical structures of Inhi-Ph and Inhi-BrPh. Weight loss measurement to the decrease of the corrosion inhibition performance. With the concentration of Inhi-Ph and Inhi-BrPh increase 100 to 100 mg L-1, the inhibition efficiencies are 92.05% and 73.98%, which further demonstrate that the inhibitor of Inhi-Ph 80 Inhi-Ph can act as an effective corrosion inhibitor for Q235 steel in 1.0 M HCl. The inhibition behavior of Q235 steel by Inhi-BrPh Inhi-Ph and Inhi-BrPh in HCl solution can be attributed to 60 the adsorption of components on Q235 steel surface, which retards the dissolution of Q235 steel by blocking its active 40 corrosion sites. S

O

CH2

S

O

Br

P

η (%)

P

η

20

0

20

40

60

80

100

3.3 Potentiodynamic polarization measurement

-1

c (mg L )

At 30 °C, all polarization curves of Q235 steel in 1.0 M HCl with different concentrations of Inhi-Ph and Inhi-BrPh Figure 3: The effectconcentration of inhibitors concentration on inhibition gure 3: The effect of inhibitors on inhibition efficiency for Q235 steelfrom in 1.0 M obtained potentiodynamic polarization measurement efficiency for Q235 steel in 1.0 M HCl at 30°C from weight loss were shown in Figure 4 (a) and (b), respectively. Based on measurement. HCl at 30°C from weight loss measurement. this measurement, the electrochemical parameters for Q235 steel corrosion in 1.0 M HCl with different concentrations of Inhi-Ph and Inhi-BrPh including corrosion potential Ecorr (mV, vs SCE), corrosion current density Icorr (μA cm-2), (%)) for

The effect of inhibitors concentration on the corresponding inhibition efficiency (ηW

5 steel in 1.0 M HCl at 30°C from weight loss measurement was exhibited in Figure 3. From

figure, it can be found that the inhibition efficiencies increase with concentration of Inhi-Ph

Unauthenticated Download Date | 12/11/17 1:11 AM

potential of Q235 steel in 1.0 M HCl with Inhi-Ph and Inhi-BrPh at 30°C K shift le 

which indicate that the Inhi-Ph and Inhi-BrPh are mixed-type inhibitor. -1.5 (a) Inhi-Ph Investigation on Two Compounds of O,O‘-dithiophosphate Derivatives as Corrosion Inhibitors... 

 267

-2.0 -2.5

-2

-2 lg (I /A cm )lg (I /A cm )

-2

-2 lg (I /A cm )lg (I /A cm )

cathodic and anodic Tafel slopes bc and ba (mV dec-1) and -1.5 (a) Inhi-Ph -3.0 the corresponding inhibition efficiency (ηP(%)) were listed -2.0 -3.5 in Table 4. -2.5 -4.0 According to Figure 4 (a), (b) and Table 4, it can be -1 -3.0 0 mg L -4.5 found that both the anodic and cathodic curves shift to -1 20 mg L -3.5 -5.0 lower current densities after addition of inhibitor in 1.0 -1 40 mg L -4.0 -5.5 M HCl, which indicate both Inhi-Ph and Inhi-BrPh can -1 -1 60 0 mg L -4.5 -6.0 reduce the Q235 steel anodic dissolution and retard the -1 20 mg L -5.0 -0.65 -0.60 -0.55 -0.50 -0.45 -0.40 -0.35 -0.30 hydrogen ion reduction. The inhibition effect enhances -1 40 mg L -5.5 E ( V ) with the increase of Inhi-Ph and Inhi-BrPh concentration, vs SCE -1 60 mg L -6.0 resulting from the adsorption of inhibitors on the Q235 -0.65 -0.60 -0.55 -0.50 -0.45 -0.40 -0.35 -0.30 steel electrode surface. The possible mechanism is the E vs SCE (V) adsorption of the inhibitors on Q235 steel surface through the electron pair of heteroatoms (S and O), and the π -1.5 (b) Inhi-BrPh electron of benzene rings in the molecular structure of -2.0 Inhi-Ph and Inhi-BrPh, which can block the Q235 steel surface and reduces the corrosive attraction of Q235 steel -2.5 -1.5 (b) Inhi-BrPh in HCl media. -3.0 Apparently, according to Table 4, the corrosion -2.0 -3.5 current density is much smaller in the presence of Inhi-Ph -2.5 -4.0 -1 and Inhi-BrPh comparing with that in the absence of Inhi0 mg L -3.0 -1 -4.5 Ph and Inhi-BrPh for Q235 steel in 1.0 M HCl, and which 20 mg L -3.5 -1 decreases with inhibitors concentration increasing. The -5.0 40 mg L -1 -4.0 -1 inhibition efficiency increase with inhibitors concentration 60 0 mg L -5.5 -1 -4.5 increasing is due to the increase of the blocked fraction of mg L -0.55 -0.50 -0.45 -0.40 -0.35 -0.30 -0.70 -0.65 20-0.60 -1 the Q235 steel electrode surface by adsorption. With Inhi-5.0 40 mg L E vs SCE (V) -1 Ph and Inhi-BrPh concentration increase to 60 mg L-1, the 60 mg L -5.5 inhibition efficiencies are 94.63% and 75.86%, this result -0.70 -0.65 -0.60 -0.55 -0.50 -0.45 -0.40 -0.35 -0.30 also reveal that the Inhi-Ph can act as good corrosion Figure 4: Polarization curves of Q235 steel in 1.0 M HCl solution with Figure 4: Polarization curves of Q235 steel in 1.0 HCl solution with different con E vsM (V ) SCE and Inhi-BrPh (b) at 30°C. inhibitor for Q235 steel in 1.0 M HCl, and the performance different concentrations of Inhi-Ph(a) of corrosion inhibition for Q235 steel in 1.0 M HCl by InhiInhi-Ph(a) (b) atcircuit 30°C.mode BrPh lower than it by Inhi-Ph. spectroscopy (EIS) and basedInhi-BrPh on the equivalent Figure 4: Polarization curves of Q235 steel in 1.0 M HCl solution with different co In addition, based on potentiodynamic polarization showing in Figure 6. The double layer capacitance (Cdl), measurement, the corrosion inhibitor can be classified as charge transfer resistance (Rct) and the corresponding Inhi-Ph(a) and(ηEInhi-BrPh (b)from at 30°C. cathodic or anodic type if the displacement in corrosion inhibition efficiency (%)) obtained EIS were potential is more than 85 Table mV with4:respect to corrosion parameters listed in Table 5. From Figure 5 (a) and (b), it inhibition can be foundefficiency of The polarization and the corresponding potential of the HCl blank solution [15-16]. According that all the Nyquist plots show a single capacitive loop, to the polarization curves showing in Figure 4 and the in both uninhibited (HCl blank solution) and inhibited 1.0 M HCl with different concentrations of Inhi-Ph and Inhi-BrPh at 30 polarization parameters listing in Table 4, it polarization can be found (HCl with Inhi-Ph Inhi-BrPh) solutions, which is efficiency o Table 4: The parameters and and the corresponding inhibition that the corrosion potentials shift slightly in the negative attributed to the charge transfer of corrosion process. The C Ecorr Icorr ba bc direction. All corrosion potential of Q235 steel in 1.0 M HCl impedance spectra show that the single semicircle and Inhibitor -1 -2 -1 1.0 M HCl with different concentrations Inhi-Ph at dec 30 (mg (mV) (μA cm )of mVand dec Inhi-BrPh ) ( mV with Inhi-Ph and Inhi-BrPh at 30°C K shift less than 85 mV,L )the diameter of semicircle increase with the(concentration which indicate that the Inhi-Ph and Inhi-BrPh are mixed- of the inhibitors. According to Table 5, it reveals that the Blank solution 0C -494 1714.65 151.56 153.37 Ecorr Icorr ba bc type inhibitor. charge transfer resistance increase and the double layer Inhibitor -1 -2 -1 Inhi-Ph 20L )capacitance -460 371.05 163.13 144.09 (mg (mV) (μA cmconcentration ) ( mV dec ) ( mV dec decease with the of inhibitors increasing. The decrease of double layer capacitance may Blank solution 0 be due to-494 1714.65 151.56 153.37 the decrease of the 3.4 Electrochemical impedance spectroscopy 9 local dielectric constant or of the electrical double Inhi-Ph 20 the increase -460of the thickness 371.05 163.13layer, 144.09 Figure 5 (a) and (b) show the Nyquist diagrams of Q235 indicating that the inhibitors adsorbed on the Q235 steel steel in 1.0 M HCl with various concentrations of Inhi-Ph surface. The increase of charge transfer resistance can 9 and Inhi-BrPh at 30°C from electrochemical impedance be attributed to the formation of protective film on the Unauthenticated Download Date | 12/11/17 1:11 AM

268 

  Chuan Lai et al.

Table 4: The polarization parameters and the corresponding inhibition efficiency of Q235 steel in 1.0 M HCl with different concentrations of Inhi-Ph and Inhi-BrPh at 30°C. Icorr (μA cm-2) 1714.65 371.05 234.74 92.08 770.05 577.67 438.03

Q235 steel/solution interface. The inhibition efficiencies recorded by EIS are 81.79% and 73.71% for Q235 steel in 1.0 M HCl with 60 mg L-1 Inhi-Ph and Inhi-BrPh. This results obtained from EIS are in good agreement with the results obtained from weight loss and potentiodynamic polarization measurement.

3.5 Adsorption isotherm 3.5 Adsorption isotherm

ba ( mV dec-1) 151.56 163.13 124.07 83.89 139.66 103.09 82.19 150

(a) Inhi-Ph

150 120

(a) Inhi-Ph

bc ( mV dec-1) 153.37 144.09 115.87 103.84 121.65 98.43 83.69

ηP (%) 78.36 86.31 94.63 55.09 66.31 74.45 0 mg L

-1 -1

2

Inhi-BrPh

Ecorr (mV) -494 -460 -456 -449 -477 -482 -473

2

Blank solution Inhi-Ph

C (mg L-1) 0 20 40 60 20 40 60

-Z' (Ω cm -Z' )(Ω cm )

Inhibitor

20 mg L -1 0 mg L -1 40 mg L -1 20 mg L-1 60 mg L -1 40 mg L

120 90

60 mg L

-1

90 60 60 30 30

The isothermcan canbebe used to analyze the The adsorption adsorption isotherm used to analyze the interaction of 0the Inhi-Ph and Inhi-BrPh 3.5 Adsorption isotherm 0 30 60 90 interaction of the Inhi-Ph and Inhi-BrPh on Q235 steel (a) Inhi-Ph 2 on Q235 steel surface. Usually, the to physisorption and chemisorption as twoand main types 0 Inhi-Ph The adsorption isotherm can both be used analyze the interaction of the Inhi-BrPh Z (Ωof cm ) surface. Usually, both the physisorption and chemisorption 0 30 60 90 as two main types of interaction are used to describe the interaction are surface. used to describe adsorption of inhibitor molecules on metal on Q235 steel Usually,the both the physisorption and chemisorption as surface. two main types ofcm2) Z (Ω adsorption of inhibitor molecules on metal surface. InInorder confi the adsorption isotherm order to confirm the reasonable reasonable adsorption isotherm for Inhi-Ph and Inhi-BrPh on Q235 interaction areto used to rm describe the adsorption of inhibitor molecules on metal (b) surface. Inhi-BrPh 100 for Inhi-Ph and Inhi-BrPh on Q235 steel surface in HCl steelsolution, invarious HCl solution, various isotherms including Frumkin, Flory–Huggins, Temkin and Insurface order to confirm the reasonable adsorption isotherm for Inhi-Ph and Inhi-BrPh on Q235 isotherms including Frumkin, Flory– (b) Inhi-BrPh 100 80 Huggins, Temkin and Langmuir adsorption isotherms are Langmuir isotherms are employed based on Frumkin, the data Flory–Huggins, of weight loss measurement steel surfaceadsorption in HCl solution, various isotherms including Temkin and Z (Ω cm ) employed based on the data of weight loss measurement 80 according to Figure 3. Fitting resultsthat reveal that the data according to Figure 3.isotherms Fitting results reveal the adsorption of Inhi-Ph and Inhi-BrPh on Q235 Langmuir adsorption are employed based on the of 60 weight loss measurement (b) Inhi-BrPh adsorption of Inhi-Ph and Inhi-BrPh on Q235 steel surface Langmuir adsorption isotherm (Equation 5)[10,11]:5)[10,11] : 60 steelobey surface obey Langmuir isotherm (Equation according to Figure 3. Fitting adsorption results reveal that the adsorption of Inhi-Ph 40 and Inhi-BrPh on Q235 150

0 mg L

2

-Z' (Ω cm )

120

20 mg L

-1

40 mg L

-1

60 mg L

-1

30

20 mg L -1 0 mg L -1 40 mg L -1 20 mg L-1 60 mg L -1 40 mg L

0

30

60

90

120

2

-Z' (Ω cm -Z' )(Ω cm )

2

-Z' (Ω cm )

80



60

60 mg L

-1

20 mg L

-1

40 mg L

-1

60 mg L

-1

-1 -1

150

0 mg L

100

40 20

150

0 mg L

2

𝐶

𝐾�d�

120

60

2

𝜃

150

90

0

[10,11] 𝐶 � steel surface = obey + 𝐶Langmuir adsorption isotherm (Equation 5)(5) :

120

-1

-1

(5)

40

= Cthe + 𝐶the concentration (5)constant equilibrium where of Inhi-Ph and Inhi-BrPh, Kads is the adsorption where of Inhi-Ph and Inhi-BrPh, 𝜃 C 𝐾is 20 �d� is concentration 0 Kads is the adsorption equilibrium constant and θ is the 0 20 40 60 80 100 (Ω cm ) and surface θC is is thethe surface coverage. surface different concentrations of ZInhi-Ph and 2 is the adsorption equilibrium constant where concentration ofThe Inhi-Ph andcoverage Inhi-BrPh, Kfor ads coverage. The surface coverage (θ) for(θ) diff erent Z (Ω cm ) 0 0 20 40 60 80 100 concentrations of Inhi-Ph and Inhi-BrPh in 1.0 M HCl is Figure 5: Nyquist diagrams Q235 steelwith in 1.0 M HClconcentrations solution withof Inhi-BrPh 1.0 M coverage. HCl is obtained based coverage on the following equation by weight loss measurement: and θ is theinsurface The surface (θ) for different concentrations of Inhi-Ph and Figure 5: Nyquist diagrams of Q235 steel in 1.0 Mof HCl solution different 2 (Ω cm ) obtained based on the following equation by weight loss different concentrations of Inhi-PhZ (a) and Inhi-BrPh (b) at 30°C. Inhi-Ph (a) and Inhi-BrPh (b) at 30°C. �� −� measurement: Inhi-BrPh in 1.0 M HCl is obtained based on the following equation by weight loss measurement: 𝜃= Figure 5: Nyquist diagrams of Q235 steel in(6) 1.0 M HCl solution with 20

0

0

20

40

60

80

100

2

��

Rct

� −�

(6) 𝜃 =v �and v are corrosionFigure 5: Q235 Nyquist diagrams ofInhi-Ph Q235 and steel in(6) 1.0 M HCl(b) solution with where rate of the steel in HCl solution without different 0 �� (a) with and Inhi-BrPh at 30°C. Rs

v corrosion are corrosion rate of the Q235 steel HClsolution without and with different where v0 and concentrations and rate Inhi-BrPh. where v0 and v of areInhi-Ph of the Q235 steel in in HCl Inhi-Ph (a) andCdlInhi-BrPh solution without and with different concentrations of InhiThe C/θ versus C yield the straight lines shown in Figure 7. While the strong Rct concentrations ofofInhi-Ph and Inhi-BrPh. Ph andplots Inhi-BrPh. Figure 6: Equivalent circuit mode.

(b) at 30°C.

Figure 6: Equivalent circuit mode.

2

>0.9959) suggest that the of shown Inhi-Phinand Inhi-BrPh on Q235 steel correlation (R of The plots C/θ versus C yield the adsorption straight lines Figure 7. While the strong

R

Rct

Table 5: The electrochemicalsparameters of impedance and the corresponding inhibition efficiency

surface in 1.0 HCl obey Langmuir isotherm. The standard free energy adsorption >0.9959) suggest that adsorption the adsorption of Inhi-Ph and Inhi-BrPh on ofQ235 steel correlation (R2M

R

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of Q235 steel in 1.0 M HCl with various concentration Inhi-Ph and Inhi-BrPh 30°C. DownloadofDate | 12/11/17 1:11atAM

s � )incan determined from theadsorption interceptsisotherm. of the straight lines according to of the followingC (𝛥𝐺�d� surface 1.0 be M HCl obey Langmuir The standard free energy adsorption Inhibitor C (mg L-1) R (Ω cm-2) p

dl

C

(μF dl cm-2)

ηE (%)

different different

according to Figure 3. Fitting results reveal that the adsorption of Inhi-Ph and Inhi-BrPh on Q235 [10,11] Investigation on Two Compounds O,O‘-dithiophosphate Derivatives as Corrosion Inhibitors...  : steel surface obey Langmuir adsorption isotherm (Equation 5)of

𝐶

=



+𝐶

𝜃 𝐾5:�d� Table The electrochemical parameters of impedance and the corresponding inhibition efficiency of Q235 steel in 1.0 M HCl with where C is the concentration of Inhi-Ph and Inhi-BrPh, Kads is various concentration of Inhi-Ph and Inhi-BrPh at 30°C.

(5)

 269

R2=0.99595 Inhi-BrPh

140

the adsorption equilibrium constant 120

p

Blank in solution Inhi-BrPh 1.0 M Inhi-Ph

𝜃=

�� −� ��

Inhi-BrPh

0 HCl 20

is

dl

E

25.44based on 78.36 obtained the

― following

θ/c (mg L-1)

and θInhibitor is the surface coverage. surface different concentrations of Inhi-Ph and C (mg L-1) The R (Ω cm-2) coverage C (μF cm-2)(θ) ηfor(%) 100

equation by weight loss measurement:

86.53

20.43

70.60

40

92.89

19.48

72.61

60

139.7

10.14

81.79

20

57.75

60.02

40

76.02

38.59

66.54

25.37

73.71

80

R2=0.99786 Inhi-Ph

(6)

60

40 where v0 and v are corrosion rate of the Q235 steel in55.95 HCl solution without and with different

concentrations of

60 Inhi-Ph

and

96.77 Inhi-BrPh.

20

20

40

60

80

100

-1

c (mg L ) The plots of C/θ versus C yield the straight lines shown in Figure 7. While the strong The plots of C/θ versus C yield the straight lines shown that the adsorption of Inhi-Ph Figure and Inhi-BrPh on Q235 steel correlation (R2>0.9959) Figure 7: Langmuir adsorption isotherm forisotherm Inhi-Ph Inhi-BrPh on Q235 steel in 1.0 M in Figure 7. While suggest the strong correlation (R2>0.9959) 7: Langmuir adsorption forand Inhi-Ph and Inhi-BrPh on Q235 steel in 1.0 M HCl at 30°C. suggest that the adsorption of Inhi-Ph and Inhi-BrPh on surface in 1.0 M HCl obey Langmuir adsorption isotherm. The standard free energy of adsorption 30°C. Q235 steel surface in 1.0 M HCl obey Langmuir adsorption �isotherm. The standard free energy of adsorption ( Tableaccording 6: The adsorption ) lines (𝛥𝐺�d� ) can be determined from the intercepts of the straight to theparameters followingfor Inhi-Ph and Inhi-BrPh on can be determined from the intercepts of the straight lines Q235 steel in 1.0 M HCl at 30°C. expression: according to the following expression:

𝐾�d� =



��.�

exp(−

� 𝛥𝐺�d�

��

Table 6: The adsorption parameters for Inhi-Ph andRInhi-BrPh 2 Inhibitor M Kon(LQ235 mol-1) steel in 1.0 M HC ads

)

30°C.(7)

Inhi-Ph

-42.51

(7) 386

0.9992

3.807×105

Inhi-BrPh -42.93 544 0.9985 4.503×10 -1 -1 ΔG (kJthe mol ) Inhibitor M R Kads (L mol ) is the gasgas constant, T is Tabsolute temperature (K) and 55.5 molar where R=8.314 J K-1J mol ads is is the constant, is absolute where R=8.314 K-1 mol temperature (K) and 55.5 is the molar concentration of Inhi-Ph -1 -42.51 386 0.9992 3.807×105 concentration of water in the solutionin expressed molarity water in the solution expressed molarityin units (mol units L-1). (mol L ). -42.93 0.9985that the 4.503×105 Meanwhile, from Figure 8 (b), 544 it is obvious Based on Equation 7, the obtained values of Kads and Inhi-BrPh for Inhi-Ph and Inhi-BrPh were listed in Table 6, as inhibition efficiency decrease with HCl concentration can be seen that the calculated values of of Inhi- increasing, the minimum inhibition efficiency for Inhi-1 Ph and7,Inhi-BrPh (60 values mg L-1) of Ph and Inhi-BrPh all lower than -40.00 kJ mol , which onKQ235and steel � 5.0 M HCl Based on Equation the obtained 𝛥𝐺in�d� for Inhi-Ph and Inhi-B ads -1 are -42.51 and -42.93 kJ mol , and it also indicates that the at 30°C are 70.01% and 56.33%. The decrease of the � HCl) to inhibition efficiency from 98.86%, values 93.67%of(0.1 adsorption processes of Inhi-Ph and Inhi-BrPh Q2356, as of Inhi-Ph and Inhi listed inonTable can be seen that the calculated 𝛥𝐺M�d� steel surface in 1.0 M HCl belongs to chemical adsorption 70.01%, 56.33% (5.0 M HCl) are contributed to the increase 12 are -42.51 andThe -42.93 kJ results mol-1, and lower than -40.00ofkJhydrogen mol-1, which ion concentration. similar wereit also indicate [10,17-18]. reported by Lu and Su [19-20]. adsorption processes of Inhi-Ph and Inhi-BrPh steel surface in 1.0 M HCl b Additional, according to theoneffQ235 ect of storage time on inhibition efficiency from Figure 8 (c), it is quite clear that 3.6 Effect of temperature, HCl concentration chemical adsorption [10,17-18]. the inhibition efficiency slightly fluctuate with storage and storage time time changing. At 30°C, in 1.0 Mand HCl storage with 60 mg L-1 Inhi-Ph 3.6 Effect of temperature, HCl concentration time According to potentiodynamic polarization measurement, and Inhi-BrPh at 168 hours later, the inhibition efficiency up to 94.90% polarization and 76.91%, measurement, respectively. The the effects of temperature (T, °C), HCl concentration (cHCl, tostill According potentiodynamic the results effects of temperatur M) and storage time (t, h) on the corresponding inhibition show that Inhi-Ph and Inhi-BrPh can act as the longM) and inhibitor, storage time h) on the corresponding inhibition e (cHCl,corrosion and (t, which further reveal that efficiency (ηP(%)) were presented in Figure HCl 8 (a), concentration (b) and (c). acting -1 Inhi-Ph can exhibit the excellent corrosion inhibition for From Figure 8 (a), as can be seen in 1.0 M HCl with 60 mg L were presented in Figure (a), (b) and (c). From Figurecompounds 8 (a), as can be seen in 1 P(%))decrease Q235 steel in HCl8 solution. Compare the ionic Inhi-Ph and Inhi-BrPh, the inhibition effi(η ciency with temperature increasing, with temperature increase -1 of N,N-diethylammonium O,O’-di(p-methoxyphenyl) with 60 mg L Inhi-Ph and Inhi-BrPh, the inhibition efficiency decrease with tem from 25°C to 45°C that the inhibition efficiency of Inhi-Ph dithiophosphate in our previous work [11] with the and Inhi-BrPh drop from 96.17%, 76.04% (25°C) to 91.08%, covalence compounds of Inhi-Ph in this increasing, with temperature increase from 25°C to and 45°CInhi-BrPh that the inhibition efficiency o 60.54% (45°C), respectively. The decrease of inhibition work, it is clearly that the covalence compounds of Inhiefficiency is due to the increasing of inhibitor moleculesdrop Ph from and Inhi-BrPh stable(25°C) presenttoin91.08%, HCl solution. and Inhi-BrPh 96.17%, can 76.04% 60.54% (45°C), respecti desorption from Q235 steel surface in 1.0 M HCl. 0

2

-1

5

13 Unauthenticated Download Date | 12/11/17 1:11 AM

-1

[19-20]. the increase of hydrogen ion concentration. The similar results were reported by Lu and Su [19-20]. 270 

  Chuan Lai et al. 100

(a)

Inhi-Ph Inhi-BrPh

(a)

Inhi-Ph Inhi-BrPh

ηP (%)

ηP (%)

80 100 60 80 40 60 20 40 0

25

30

20

35

T(



0

25

30

35

T(



100

(b)

Inhi-Ph Inhi-BrPh

(b)

Inhi-Ph Inhi-BrPh

60 20 40 0 20

0

1

2

3

4

45

80

ηP (%)

40

40

100

ηP (%)

ηP (%) ηP (%)

80

45

)

80 100 60

40

)

5

cHCl (M)

100 60

(c)

Inhi-Ph Inhi-BrPh

(c)

Inhi-Ph Inhi-BrPh

80 40 60 20 40 0 20

0

24

48

72

96

120

144

168

t (h)

0

0

Figure 8: The (b), and storage time on inhibition from potentiodynamic polarization 0 effect1of temperature 2 3(a), HCl4 concentration 5 0 (c)24 48 72 efficiency 96 120 144 168 measurement. Figure 8: The effect ofc temperature (a), HCl concentration (b), and storage time (c) on inhibition (M) t (h) HCl

polarization measurement. of Material Corrosion and Protection Key Laboratory 4 Conclusions efficiency from potentiodynamicproject Figure 8: The effect of temperature (a), HCl concentration (b), and storage time (c) on inhibition of Sichuan Province (No. 2017CL02), the project of Key to the effect of storage time Laboratories on inhibition efficiency from 8 (c), of Fine Chemicals andFigure Surfactants in Sichuan In Additional, conclusion, according the new corrosion inhibitors of S-4efficiency from potentiodynamic polarization measurement. methylbenzyl-O,O’-di(phenyl) dithiophos- phate (Inhi- Provincial Universities (No. 2016JXZ03), the project of it isPh) quiteand clear that the inhibition efficiency slightly fluctuate storage time changing. At 30°C,Property Zigongwith Science & Technology and Intellectual S-4-methylbenzyl-O,O’-di(4-bromophenyl) Additional, according to the effect of storage time on inhibition efficiency from Figure 8 (c), dithiophosphate (Inhi-BrPh)-1 were synthesized and Bureau (Nos. 2015HX18, 2015CXM01), and the opening 168 hours the inhibition efficiency in confirmed 1.0 M HCl 60 mganalysis, L Inhi-Ph 1 13 of Keylater, Laboratory of Green Catalysis of Sichuan bywith elemental FT-IR,and H, Inhi-BrPh C and 31P atproject it is quite clear that the inhibition efficiency slightly fluctuate with storage time changing. At 30°C, NMR in this work. The evaluation of corrosion inhibition Institutes of High Education (No. LZJ14201). stillperformance up to 94.90% respectively. results show that Inhi-Ph and Inhi-BrPh can act showand that 76.91%, the corrosion inhibitors ofThe Inhi-Ph in 1.0 M HCl with 60 mg L-1 Inhi-Ph and Inhi-BrPh at 168 hours later, the inhibition efficiency and Inhi-BrPh for Q235 steel in HCl solution both are mixed- Conflict of interest: Authors state no conflict of interest. as type the inhibitor, long-acting corrosion inhibitor, and which further reveal that Inhi-Ph can exhibit the the inhibition efficiency increase with Inhistill up to 94.90% and 76.91%, respectively. The results show that Inhi-Ph and Inhi-BrPh can act as

Ph and Inhi-BrPh concentration increasing, decrease 14 with HCl concentration and temperature increasing. In the long-acting corrosion inhibitor, and which further reveal that Inhi-Ph can exhibit the References addition, the adsorption of Inhi-Ph and Inhi-BrPh on Q235 steel surface obeys Langmuir isotherm, which belongs 14 to [1] Gupta C., Ahamad I., Singh A., Xu X.H., Sun Z.P., Lin Y.H., chemical adsorption. Experimental study and theoretical simulations of some Acknowledgments: This project is supported financially by the program of Science and Technology Department of Sichuan Province (Nos. 2017JY0180, 2016GZ0172, 2016JY0048, 2016086), the program of Education Department of Sichuan Province (No. 17ZB0380), the project of Dazhou City (No. KJJ2016002), the opening

indolinone aased mannich bases as novel corrosion inhibitors for mild steel in acid solutions, Int. J. Electrochem. Sci., 2017, 12, 6379-6392. [2] Li X.H., Deng S.D., Lin T., Xie X.G., Du G.B., 2-Mercaptopyrimidine as an effective inhibitor for the corrosion of cold rolled steel in HNO3 solution, Corros. Sci., 2017, 118, 202- 216.

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Investigation on Two Compounds of O,O‘-dithiophosphate Derivatives as Corrosion Inhibitors... 

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