1. International Journal of Advanced Research in Engineering and Technology (IJARET), ISSN 0976 –
6480(Print), ISSN 0976 – 6499(Online) Volume 5, Issue 4, April (2014), pp. 38-45 © IAEME
38
CORROSION INHIBITION OF CARBON STEEL IN NaCl AND HCl
SOLUTIONS BY VITAMIN C
Nadir Mohamed Abdulreda
Electrochemical Eng. Dept. / College of Engineering / Babylon University, Iraq
ABSTRACT
In this study was investigated the effect of Vitamin C (VC) as a green inhibitor for carbon steel
corrosion in 3% NaCl and 4% HCl solution, the experiment was carried in different concentration of
Vitamin C and in different time. The results show that VC work as inhibitor in HCl solution better
than in NaCl solution, because it was got 70-80% efficiency and it was increased with increasing in
inhibitor concentration. Results show that time effect on inhibitor efficiency which shows that with
increasing time, the inhibitor efficiency was decrease suddenly because the inhibitor decomposed
with time and this lead to inhibitor ability for protection in which inhibitor efficiency decrease
24-50%. The inhibitor efficiency increasing with VC concentration increasing.
Keywords: Corrosion, Green Inhibitor Corrosion Inhibitor, Adsorption Isotherm.
INTRODUCTION
Corrosion control of metal (carbon steel) is of technical economical environmental and
aesthetical importance. The use of inhibitor is one of the best options of protecting carbon steel
against corrosion, the environmental toxic of organic corrosion inhibitors has prompted the search
for green corrosion inhibitors as they are biodegradable do not contain heavy metals or other toxic
compounds as an addition to being environmentally friendly and ecologically acceptable. [1]
Several protective measures are taken to control / Prevent corrosion, one of them being the
use of inhibitors. A corrosion inhibitor is a substance which added to corrosive environment,
significantly decreases the rate of corrosion attack caused by environment. Corrosion inhibitor are
commonly added in small amounts to pickling acids, acid stimulation fluids, cooling waters, oil and
gas production streams, either continuously or intermittently to control corrosion. [2]
Corrosion inhibitor generally controls corrosion by forming various types' films that modify
the environments corrosiovity at the metal surface. Inhibitors form films in several ways; by
adsorption, the formation of bulky precipitates and/or formation of passive layer on the metal
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2. International Journal of Advanced Research in Engineering and Technology (IJARET), ISSN
6480(Print), ISSN 0976 – 6499(Online) Volume 5, Issue 4, April (2014), pp.
surface. Some inhibitors retard corrosion by adsorption to form a thin, invisible film only a few
molecules thick. Other form bulky precipitates tat coat the metal and protect it from attack. A third
mechanism consists of causing the metal to corrode in each a way that a combination of adsorption
and corrosion product forms a passive film. [3]
Several heterocyclic organic compound [4
corrosion inhibitor property of organic compounds having heteroatoms such as N, S and O of high
electron density is already established
which pause various threats when charging
concern for most of chemical suppliers and operators who have to comply with the increasing more
stringent rules used. [5].
In the present work it was examined the corrosion inhibition of carbon steel in
4% HCl solution by used Vitamin C
different concentration. Adsorption mechanism was studied
from the result it can be consider that Vitamin C is a good
non-toxic and it can be said that its good for protection of carbon steel, but need to maintain the
concentration of it with time because of its decomposition with time
EXPERIMENTAL WORK
Materials
Sheet of carbon steel (C0.16%, Mn0.5%Si, 0.25%, Cr0.02%)
cm) dimensions was used for investigations
of the specimen by abraded with ambry paper abrasive (400
acetone then dried in room temperature and stored in a moisture free desiccator before their use in
corrosion studies
Inhibitor
Vitamin C (VC) was used with different concentration (0, 1, 3 and 3) g/l as inhibitor, figure
1, shows the chemical formula and structure Vitamin C.
Figure 1: Show Vitamin C (VC) chemical structures, the chemical formula (
International Journal of Advanced Research in Engineering and Technology (IJARET), ISSN
6499(Online) Volume 5, Issue 4, April (2014), pp. 38-45 © IAEME
39
Some inhibitors retard corrosion by adsorption to form a thin, invisible film only a few
molecules thick. Other form bulky precipitates tat coat the metal and protect it from attack. A third
mechanism consists of causing the metal to corrode in each a way that a combination of adsorption
and corrosion product forms a passive film. [3].
heterocyclic organic compound [4] have been reported as corrosion inhibitors, the
property of organic compounds having heteroatoms such as N, S and O of high
electron density is already established, but most of the synthetic organic inhibitors are toxic in nature
which pause various threats when charging, discharging at the various streams. This is a recent
concern for most of chemical suppliers and operators who have to comply with the increasing more
In the present work it was examined the corrosion inhibition of carbon steel in
solution by used Vitamin C (with different concentration 0,1,2, and , 3 g/l )
. Adsorption mechanism was studied by used Langumuir adsorption isotherm
t can be consider that Vitamin C is a good example for green inhibitor because it is
toxic and it can be said that its good for protection of carbon steel, but need to maintain the
concentration of it with time because of its decomposition with time.
carbon steel (C0.16%, Mn0.5%Si, 0.25%, Cr0.02%), with (3.0 cm× 3.0 cm × 0.2
cm) dimensions was used for investigations, the mass loss technique was used after the preparation
abraded with ambry paper abrasive (400, grit) washed in absolute ethanol and
acetone then dried in room temperature and stored in a moisture free desiccator before their use in
Vitamin C (VC) was used with different concentration (0, 1, 3 and 3) g/l as inhibitor, figure
chemical formula and structure Vitamin C.
chemical structures, the chemical formula (C6H8O6
weight 176.12g/mole
International Journal of Advanced Research in Engineering and Technology (IJARET), ISSN 0976 –
© IAEME
Some inhibitors retard corrosion by adsorption to form a thin, invisible film only a few
molecules thick. Other form bulky precipitates tat coat the metal and protect it from attack. A third
mechanism consists of causing the metal to corrode in each a way that a combination of adsorption
] have been reported as corrosion inhibitors, the
property of organic compounds having heteroatoms such as N, S and O of high
, but most of the synthetic organic inhibitors are toxic in nature
treams. This is a recent
concern for most of chemical suppliers and operators who have to comply with the increasing more
In the present work it was examined the corrosion inhibition of carbon steel in 3% NaCl and
(with different concentration 0,1,2, and , 3 g/l )as inhibitor with
by used Langumuir adsorption isotherm,
example for green inhibitor because it is
toxic and it can be said that its good for protection of carbon steel, but need to maintain the
(3.0 cm× 3.0 cm × 0.2
was used after the preparation
bsolute ethanol and
acetone then dried in room temperature and stored in a moisture free desiccator before their use in
Vitamin C (VC) was used with different concentration (0, 1, 3 and 3) g/l as inhibitor, figure -
6), and Molecular

3. International Journal of Advanced Research in Engineering and Technology (IJARET), ISSN 0976 –
6480(Print), ISSN 0976 – 6499(Online) Volume 5, Issue 4, April (2014), pp. 38-45 © IAEME
40
Solution
It was used two different solutionsas aggressive solutions, 1 M HCl and 3% NaCl .These
solutions were prepared by dilution of analytical grade 98% HCl and analytical NaCl with distilled
water respectively.
Equipment
Glass equipment (Beaker, Flask, etc.) with different size, water bath (Thermolab Industries –
Model H103 – 10 liter capacity – Temp. range 30-90 º C), digital balance (Sartorius –Model TE214S
with accuracy d=0.1 mg), desiccator.
RESULTS & DISCUSSION
Weight loss measurement
Weight loss of carbon steel in 1 M HCl solution was determined in absence and presence
(with different concentration) of Vitamin C (VC) as inhibitor with different immersion time (2, 4, 6
and 24) hour, Table 1 show the results of weight loss investigations, while Table 2 show the weight
loss results for carbon steel in 3% NaCl solution with the same condition of inhibitor concentration
and immersion time.
Table 1: weight loss for carbon steel in 1 M HCl solution in absence and presence of VC as inhibitor
with different time
Time (Hours)
VC Conc.(g/l)
0 1 2 3
2 0.0181 0.00144 0.0017 0.0012
4 0.0417 0.0088 0.00814 0.00613
6 0.0621 0.0265 0.0169 0.0149
24 0.2832 0.1503 0.1575 0.1466
0
0.05
0.1
0.15
0.2
0.25
0.3
0 5 10 15 20 25 30
Weightloss(grams)
Time (hr)
Balnk
1 g / l VC
2 g / l VC
3 g / l VC
Figure 2: show result weight loss investigations with as a function of inhibitor concentration and
immersion time for carbon steel in 1 M HCl solution

4. International Journal of Advanced Research in Engineering and Technology (IJARET), ISSN 0976 –
6480(Print), ISSN 0976 – 6499(Online) Volume 5, Issue 4, April (2014), pp. 38-45 © IAEME
41
Table 2: weight loss for carbon steel in 3% NaCl solution in absence and presence of VC as inhibitor
with different time
Time (Hours)
VC Conc.(g/l)
0 1 2 3
2 0.000834 0.00053 0.00045 0.00041
4 0.0009 0.00068 0.00068 0.00062
6 0.0017 0.0013 0.0009 0.0011
24 0.0070 0.0052 0.00464 0.004
0
0.001
0.002
0.003
0.004
0.005
0.006
0.007
0.008
0 5 10 15 20 25 30
weightloss(grams)
Time (hr)
Balnk
1 g / l VC
2 g / l VC
3 g / l VC
Figure 3: show result weight loss investigations with as a function of inhibitor concentration and
immersion time for carbon steel in 3% NaCl solution
Table 3: Vibration of corrosion rate with time and VC (inhibitor) concentration for carbon steel in 1
M HCl solution, also the values of inhibitor efficiency (η) and, surface coverage (θ) were tabled
Time (Hr) VC concentration
(g/l)
Corrosion rate
( g / m2
h)
Inhibitor efficiency η Surface coverage θ
2 0 0.0181 - 0.00
1 0.00144 92 0.92
2 0.0017 91 0.91
3 0.0012 93 0.93
4 0 0.0417 - 0.00
1 0.0088 79 0.79
2 0.00814 80 0.80
3 0.00613 85 0.85
6 0 0.0621 - 0.00
1 0.0265 57 0.57
2 0.0169 73 0.73
3 0.0149 76 0.76
24 0 0.2832 - 0.00
1 0.1503 47 0.47
2 0.1575 44 0.44
3 0.1466 48 0.48

5. International Journal of Advanced Research in Engineering and Technology (IJARET), ISSN 0976 –
6480(Print), ISSN 0976 – 6499(Online) Volume 5, Issue 4, April (2014), pp. 38-45 © IAEME
42
0
20
40
60
80
100
120
0 1 2 3 4
Inhibitorefficincyη%
Concentration ( g / l)
Time 2 Hr
Time 4 Hr
Time 6 hr
Time 24 Hr
Figure 4: show inhibitor efficiency as a function of time and inhibitor concentration for carbon steel
corrosion in 1 M HCl solution
It's clear that the inhibitor efficiency was increase with inhibitor concentration increasing as
well as the surface coverage, but increasing is low with increasing in time of immersion.
Table 4: Vibration of corrosion rate with time and VC (inhibitor) concentration for carbon steel in
3% NaOH solution, also the values of inhibitor efficiency (η) and, surface coverage (θ) were tabled
Time (Hr) VC
concentration
(g/l)
Corrosion rate
( g / m2
h)
Inhibitor
efficiency η
Surface coverage θ
2 0 0.082 0 0.00
1 0.0507 38 0.38
2 0.0434 47 0.47
3 0.0394 52 0.52
4 0 0.0433 0 0.00
1 0.0329 24 0.24
2 0.0324 37 0.37
3 0.0199 54 0.54
6 0 0.0545 0 0.00
1 0.0409 25 0.25
2 0.0288 40 0.40
3 0.0347 36 0.36
24 0 0.0561 0 0.00
1 0.0417 26 0.26
2 0.0372 34 0.34
3 0.0321 43 0.43

6. International Journal of Advanced Research in Engineering and Technology (IJARET), ISSN 0976 –
6480(Print), ISSN 0976 – 6499(Online) Volume 5, Issue 4, April (2014), pp. 38-45 © IAEME
43
0
10
20
30
40
50
60
0 0.5 1 1.5 2 2.5 3 3.5
InhibitorEffecincyη%
Concentration ( g /l)
Time 2 Hr
Time 4 Hr
Time 6 Hr
Time 24 Hr
Figure 5: show inhibitor efficiency as a function of time and inhibitor concentration for carbon steel
corrosion in 3% NaOH solution
Adsorption considerations
The adsorption of inhibitor molecules from aqueous solutions can be regarded as a quasi-
substitution process between the organic compound in the aqueous phase Org (aq) and water
molecules at the electrode surface, H2O(s).
Org (aq) + x H2O (s) → Org (s) + x H2O (aq)
The adsorption of organic compounds can be described by two mains types of interaction;
physical adsorption and chemisorption .they are influenced by the nature of the change of the metal,
the chemical structure of inhibitor, pH, the type of electrolyte and temperature [6].
So adsorption isotherms are very important in determining the mechanism organic
electrochemical reaction [7], the most frequently used isotherms are Langmuir, FrumKin, Temkin,
Flory-Huggin, and etc. all these isotherms are of general form
KCaxf =− )2exp(),( θθ
Langmuir adsorption isotherm was found to be suitable for the experimental findings; the
isotherm is described by equation [8]
(3)C
1C
+=
adsKθ
Where C is inhibitor concentration, Kads is adsorption equilibrium constant and θ is the
surface coverage and n is constant, and the adsorption free energy was estimated from the following
equation, adsorption equilibrium constant was calculated from plot at figure 8 , the value of them (
adsorption equilibrium constant and free energy ) were listed in table 3.

7. International Journal of Advanced Research in Engineering and Technology (IJARET), ISSN 0976 –
6480(Print), ISSN 0976 – 6499(Online) Volume 5, Issue 4, April (2014), pp. 38-45 © IAEME
44
(4)555ln
exp
5.55
1
)K.(-RT∆G
RT
G
K
adsads
ads
ads
=





 ∆−
=
o
0
1
2
3
4
5
6
7
0 0.5 1 1.5 2 2.5 3 3.5
C/θ
Inhibitor Concentration ( g / l)
HCl solution
NaCl solution
Figure 6: Langmuir adsorption isotherms for vitaime C (VC) on carbon steel in 1 M HCl solution
and in 3% NaCl solutionthe imerssion time is 2 hours
Table 5: Inhibitor adsorption constant and free energy of founded by use Langmuir adsorption
isotherm for carbon steel in 1 M HCl solution and 3% NaCl solution with different concenctartion of
inhibitor ( VC) , the imerssion time is 2 hours
Solution Kads adsorption equilibrium Free energy ∆Gads kJ/mol
1 M HCl 23.64 -17787.36
3% NaCl 0.94 -9807.68
From table (4) it is noted that ∆Gads, values have negative sign indicating that adsorption
process proceeds spontaneously and increase as the percentage inhibition increase, the high values
of adsorption constant Kads values suggest that molecules are strongly adsorbed onto mild steel
surface [9].
CONCLUSIONS
Based on the above results the following conclusion can be drawn:
• The ability of use vitamin C as inhibitor is depend on the kind of the corrosive media, i.e. in
4% HCl solution work inhibitor better then in 3% NaCl solution.
• Increasing in inhibitor efficiency increased with Vitamin C concentration.
• Immersion time shows that opposite effect on inhibitor efficiency; the inhibitor efficiency was
decreased with increasing immersion time and this is because of decomposition of Vitamin C
with time.
• It can be consider that Vitamin C is a good example for green inhibitor because it is non-toxic
and it can be said that its good for protection of carbon steel, but need to maintain the
concentration of it with time because of its decomposition with time.

8. International Journal of Advanced Research in Engineering and Technology (IJARET), ISSN 0976 –
6480(Print), ISSN 0976 – 6499(Online) Volume 5, Issue 4, April (2014), pp. 38-45 © IAEME
45
ACKNOWLEDGMENTS
The author would like to thank the Electrochemical Engineering Department at Babylon
University for supporting and approving this research.
REFERNCES
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[2] E.E.Oguzie ,Y.Li., F.H.Wang. Studies on the inhibitive effect of Occimumviridis extract on
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[3] Hameed Hussein Alwan , Adsorption Mechanism for Corrosion Inhibition of Carbon steel on
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[4] S.A. Umoren, I.B. Obot, E.E. Ebenso, N.O. Obi-Egbedi, Synergistic Inhibition between
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[5] Alan W. Armoura and Dennis R. Robitailleb, Corrosion Inhibition by Sodium Molybdate, J.
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[7] Xiumei Wang , Huaiyu Yang ,Fuhui Wang , An investigation of benzimidazole derivatives as
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[8] M.BenabdallahA.Aouniti and coworker l, investigation of the inhibitive of Triphenyltin 2 thio
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