Study of the Iron Behavior in Acid Rain Water Solution by Application of Two Green Corrosion Inhibitors Meryem Zouarhi *, Said Abbout , Hind Hammouch , Mohamed Chellouli ,

Hamid Erramli , Hassane Said Omar Said , Naima Bettach and Najat Hajjaji .

Team of Materials Electrochemistry and Environment,

Laboratory (LCOCE), Department of Chemistry, Faculty of

Sciences, University Ibn Tofail, Kenitra, Morocco

zouarhi.meryem@gmail.com / meryem.zouarhi@uit.ac.ma

Tel.: +212 640 260 923.

Introduction

Due to its low cost and availability, iron is

considered one of the most important and

widely used metals in many industrial

applications

Negatively affects the

physicochemical

properties of the metal

.

Different techniques are

applied to suppressing or

at least mitigating the rate

of corrosion of metals and

their alloys, among which

the use of corrosion

inhibitor

Resulting in enormous

economic and environmental

losses often difficult to

eliminate completely

The iron structure is extremely

susceptible to corrosion in

many circumstances, including

humidity, corrosive agents and

polluted atmosphere

“ The chemical compounds extracted from plants are the new alternative adapted as green corrosion inhibitors, this ecological alternative is environment-friendly, safe

and biodegradable. Team from the Materials,

Electrochemistry and Environment Laboratory

(LCOCE) of Kenitra (Morocco)

Faculty of Sciences and Techniques of Maroni University (Comoros)

The valuation of oils extracted from Jatropha curcas and Aleurites moluccana seeds for their use as green corrosion inhibitors

Purpose

“

▷Jatropha curcas and Aleurites moluccana are two species belonging to the Euphorbiaceae family. Their seeds are rich in oil which has a renowned

potential, exploited for the biodiesel production.

Plants Presentation

Jatropha curcas Aleurites moluccana

Fatty Acids composition of Jatropha curcas and Aleurites moluccana seeds oils

Stearic Acid (C18:0)

Oleic Acid (C18:1)

Linoleic Acid (C18:2)

Linoleinic Acid (C18:1)

0.5%

49%

13.5%

29%

6.2%

23%

38.8%

29%

Jatropha curcas

Palmetic Acid (C16:0) 8%

3%

Aleurites moluccana

Unsaturated fatty acids: 78.5% 90.8%

After extracting and

characterizing of the

seed oils

We aimed to evaluate and compared the inhibiting effect of the two green formulations containing oils extracted from the seeds of Jatropha curcas

(labeled JAC) and Aleurites moluccana (labeled ALM), toward the iron corrosion in the aggressive acid rain atmosphere.

Experimental study

Developed two

formulations

(JAC and ALM)(*)

based on the extracted

oils

Evaluate as a green

inhibitors of iron

corrosion in

acidic medium

(*)N. Hajjaji, N. Bettach, H. Hammouch, A. Srhiri, A. Dermaj, D. Chebabe. OMPIC Casablanca, Morocco. Patent

N3069/10.2011.

Counter electrode

Working electrode

Reference electrode

Schema for the electrochemical assembly

Elements Si Mn C P S Fe

%Weight 0 ,201 0,514 0,157 0,007 0,009 ≥ 99%

Iron composition :

Solution corrosive :

Potentiostat SP 200:

Simulated solution to acid rain water (noted AR) at a pH = 3.6. Composition: 0,2g/l NaCl ; 0,2g/l NaHCO3 and 0.2g/l Na2SO4 .

Electrochemical measurements stationary and transient

analysis :

Surface Analysis : (MEB/EDX) 8

Results And Discussion

Discussion

Histograms of the evolution of the inhibitory efficacy of JAC and ALM formulations as a function of the concentration

100 150 200 250

0

20

40

60

80

100 82,02 83,63 84,71

89,54

53,8

72,7

91,9 92,8

Concentration (ppm)

IE(%

)

Elecrochimical Impedance

Formulation (JAC)

Formulation (ALM)

0

20

40

60

80

100

100 150 200 250

86,39 91,9 93,06

96,8

64,4 76

90,3 97,2

IE(%

) Concentration (ppm)

Electrochimical Polarization

Formulation (JAC)

Formulation (ALM)

10

Concentration effect of JAC and ALM formulations

Open circuit potential (OCP)

0 200 400 600 800 1000 1200 1400 1600 1800

-0,52

-0,50

-0,48

-0,46

-0,44

-0,42

-0,40

-0,38

-0,36

-0,34

-0,32

AR solution (pH=3.6)

250 ppm JAC

250 ppm ALM

EV

SS

CE

/ V

Time, t / s

Variation of the open-circuit potential of iron in acidic rainwater solution at 250 ppm of the JAC and ALM formulations.

-1,0 -0,8 -0,6 -0,4 -0,2 0,0 0,2

1E-5

1E-4

1E-3

0,01

0,1

1

I co

rr (

mA

/cm

-2)

E / VECS

Blank (0 rpm)

250ppm JAC (0 rpm)

250ppm ALM (0 rpm)

-1,0 -0,8 -0,6 -0,4 -0,2 0,0 0,2

1E-6

1E-5

1E-4

1E-3

0,01

0,1

1

I co

rr (

mA

/cm

-2)

E / VECS

BlanK (1500 rpm)

250 ppm JAC

(1500 rpm)

250 ppm ALM

(1500 rpm)

. Potentiodynamic polarization curves of iron substrate in the AR solution containing 250 ppm of the JAC and ALM formulations, at various rotation speeds

Rotating disc electrode effect of the JAC and ALM formulations

Mixed inhibitors

The corresponding reaction in the aerated acid rain solution at pH = 3.6 is expressed by Eq: O2 + 4H + 4e- → 2H2O (1) 2H+2e- → H2 (2)

Fe → Fe2++ 2e- (3)

Kinetic parameters determined from polarization curves of the iron substrate in the AR

solution without and with inhibitors

Kinetic parameters determined from polarization curves of the iron substrate in the AR

solution without and with inhibitors

Current density (Icorr )

Without Rotation

speed (0 rpm)

Ecorr

(mV/SCE)

Icorr

(µA/cm2)

-βc

(mVdec-1)

βa

(mVdec-1)

IE

(%)

AR Solution

(pH=3.6) -512.10.9 75.570.10 271.10.8 103.20.7 -----

250 ppm of JAC -457.40.6 2.510.07 97.30.4 111.10.8 96.70.2

250 ppm of ALM

-384.20.7 2.030.05 89.50.3 128.40.4 97.30.1

With Rotation speed

(1500 rpm)

Ecorr

(mV/SCE)

Icorr

(µA/cm2)

-βc

(mVdec-1)

βa

(mVdec-1)

IE

(%)

AR Solution

(pH=3.6) -418.30.8 100.420.09 278.40.7 176.30.9 -----

250 ppm of JAC -449.40.8 1.770.03 110.10.5 140.40.9 98.20.4

250 ppm of ALM -260.10.7 0.070.01 178.60.6 54.8.0.9 99.90.3

Kinetic parameters determined from polarization curves of the iron substrate in the AR solution without and with 250 ppm of the JAC and ALM formulations, respectively.

Inhibition efficiency (IE)

0 500 1000 1500 2000 2500 3000 3500 4000 4500 5000 5500 6000

0

500

1000

1500

2000

2500

3000

3500

4000

10 Hz

10KHz

1KHz

0.1 Hz

0.01 Hz

0.01 Hz

10 Hz

0.1 Hz

-Im

ag

ina

ry p

art

(O

hm

.cm

2)

Real part (Ohm.cm2)

Blank (0 rpm)

250 ppm JAC (0 rpm)

250 ppm ALM (0 rpm)

400 500 600 700 800

0

100

200

1KHz

10Hz

1 Hz

0.01 Hz

0.1 Hz

-Im

ag

inary

part

(O

hm

.cm

2)

Real part (Ohm.cm2)

0 5000 10000 15000 20000 25000 30000 35000

0

5000

10000

15000

20000

25000

0.01 Hz10 Hz

1 Hz

0.1 Hz

0.1 Hz

0.01 Hz

-Im

ag

inary

part

(O

hm

.cm

2)

Real part (Ohm.cm2)

Blank (1500 rpm)

250ppm JAC (1500 rpm)

250ppm ALM (1500 rpm)

400 450 500 550 600

-50

0

50

100

1KHz

10Hz

0.01 Hz

0.1 Hz

-Im

ag

inary

part

(O

hm

.cm

2)

Real part (Ohm.cm2)

Impedance diagrams of iron substrate in the

AR solution without and with 250 ppm of the

JAC and ALM formulations at various

rotation speeds

Electrochemical data derived from the EIS spectra of iron of the iron substrate in the AR solution without and with

inhibitors

Electrochemical data derived from the EIS spectra of the iron substrate in the AR solution without and with 250 ppm of the JAC and ALM formulations, respectively.

Without Rotation

speed (0 rpm) Rs

(Ohm.cm2)

CHF

(µF/cm2)

RHF

(Ohm.cm2)

CBF

(µF/cm2)

RBF

(Ohm.cm2) Rp

(Ohm.cm2)

AR solution

(pH=3.6)

433.10.9 82.150.16 164.30.6

702.100.26

203.40.6

367.10.8

Inhibitors Rs

(Ohm.cm2)

Cf

(µF/cm2)

Rf

(Ohm.cm2)

Cd

(µF/cm2)

Rt

(Ohm.cm2)

Rp

(Ohm.cm2)

I E(%)

250 ppm JAC 415.20.6 3.780.06

474.11.1

103.040.19 3036.42.8

3510.25.6

89.50.1

250 ppm ALM 424.30.7 6.920.03

1944.32.3

67.530.32

3124.21.9

5068.13.1

92.80.1

With Rotation

speed (1500 rpm) Rs

(Ohm.cm2)

CHF

(µF/cm2)

RHF

(Ohm.cm2)

CBF

(µF/cm2)

RBF

(Ohm.cm2) Rp

(Ohm.cm2)

AR solution

(pH=3.6)

400.10.3 217.350.18 62.30.4

3197.103.22

66.40.3

69.10.8

Inhibitors Rs

(Ohm.cm2)

Cf

(µF/cm2)

Rf

(Ohm.cm2)

Cd

(µF/cm2)

Rt

(Ohm.cm2)

Rp

(Ohm.cm2)

I E(%)

250 ppm JAC 361.30.5 0.1860.014

2102.11.6

54.640.09 8472.43.5

10574.24.1

99.30.2

250 ppm ALM 444.30.8 2.7320.023

7284.51.3

17.140.21

27002.24.2

34286.12.2

99.80.1

Electrochemical data derived from the EIS spectra of iron of the iron substrate in the AR solution without and with

inhibitors

Th

e C

ap

acitie

s T

he

Re

sist

an

ces

0 2000 4000 6000 8000 10000 12000 14000

0

2000

4000

6000

8000

10000

10 Hz

1 Hz

0.1 Hz

0.1 Hz

0.1 Hz

0.01 Hz

0.01 Hz0.01 Hz

JAC 30 min

ALM 30 min

JAC 24h

ALM 24h

-Im

ag

ina

ry p

art

(O

hm

.cm

2)

Real part (Ohm.cm2)

0 500 1000 1500 2000

0

500

1000

1500

-Im

ag

ina

ry p

art

(O

hm

.cm

2)

Real part (Ohm.cm2)

Nyquist impedance diagrams of iron electrode in the AR solution containing 250 ppm of the JAC

and ALM formulations at different immersion time.

Immersion

time

Inhibitors Rs

(Ohm.cm2)

Cf

(µF/ cm2)

Rf

(Ohm.cm2)

Cdl

(µF/ cm2)

Rt

(Ohm.cm2)

Rp

(Ohm.cm2)

30 min JAC 415.20.4 3.780.04 474.50.3 103.040.53 3036.31.9 3510.23.3

ALM 424.10.3 6.920.07 1944.42.3 67.530.33 3124.22.3 5068.11.1

24h JAC 448.30.3 1.650.03 2501.11.2 21,070.09 10012.44.3 12512.95.3

ALM 476.20.5 5.120.09 2627.31.3 26.580.12 7936.11.5 10564.54.7

Electrochemical impedance parameters determined from Nyquist plot of iron substrate in the AR solution containing 250ppm of the JAC and ALM inhibitors at different immersion time.

Immersion time effect of the JAC and ALM formulations

a) Immersed in a AR solution (pH=3.6)

b) Immersed in an acid solution at 250 ppm in JAC formulation

SEM and EDX spectrum of iron samples after 24 hours of immersion time

Etude de l’effet inhibiteur

c) Immersed in an acid solution at 250 ppm in ALM formulation

17

Surface Analysis

Conclusion

Fatty acid analysis has shown that Jatropha curcas and Aleurites moluccana seed oils are a major source of unsaturated fatty acids.

According to obtained results and the potentiodynamic polarization plots demonstrated that JAC and ALM can effectively reduce the corrosion current density as a function of the concentration and rotation speed, indicating the mixed type protection character.

The both formulations indicated the same behavior and results deducted from the polarization plot, proving that the inhibition efficiency is mainly due to the influence of unsaturated fatty acids.

The hydrodynamic effect sharply influences the current density and the polarization resistance values, as well as the inhibitors's ability to protect iron

against corrosion in an acidic solution. In the presence of the two formulations, the Inhibition efficiency increases considerably. However, this effect is more pronounced for the ALM formulation.

The EIS plots were affected by the two studied variables, the sizes of the loops increased with the increase in the immersion time, which is more evidence for the JAC formulation.

The good inhibitory effect of JAC and ALM attribute to the formation of a protective barrier composed of the fatty acid molecules on the metal surface.

Thank you for your attention