Inhibition Effect of Benzohydrazide Derivatives on Corrosion Behaviour of Mild Steel in 1 M HCl
Hindawi Publishing Corporation
Journal of Chemistry
Volume 2013, Article ID 541691, 7 pages
http://dx.doi.org/10.1155/2013/541691
Research Article
Inhibition Effect of Benzohydrazide Derivatives on Corrosion
Behaviour of Mild Steel in 1 M HCl
P. Mohan, R. Usha, G. Paruthimal Kalaignan, and V. S. Muralidharan
Advanced Materials Research Laboratory, Department of Industrial Chemistry, Alagappa University, Karaikudi 630 003, India
Correspondence should be addressed to G. Paruthimal Kalaignan;
Received 23 January 2012; Revised 4 June 2012; Accepted 6 June 2012
Academic Editor: Ali Nokhodchi
Copyright © 2013 P. Mohan et al. is is an open access article distributed under the Creative Commons Attribution License, which
permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.
e inhibiting effect of N-benzylidenebenzohydrazide (BBH) and N� -(3-phenylallylidene) benzohydrazide (PABH) on the
corrosion inhibition of mild steel in 1 M HCl solutions were determined by weight loss and electrochemical methods. ese
inhibitors were adsorbed on the surface according to Langmuir adsorption isotherm. Both BBH and PABH have offered inhibition
efficiencies upto 97%. e free energy of activation for the corrosion process has suggested the participation of these molecules in
the corrosion process. e adsorbed inhibitor complex has offered barrier protection and prevented the corrosion. e dissolution
of iron was also retarded thereby they inhibited corrosion. e surface morphology analysis con�rmed the presence of a �lm on
the surface.
1. Introduction
Acidizing inhibitors are added to reduce base metal corrosion
[1]. Most of the acid corrosion inhibitors are organic compounds such as those containing N, S, O, and aromatic rings.
ey adsorb on the metal surface. In most of the studies,
the formation of donor-acceptor surface complexes between
free or 𝜋𝜋 electrons of an inhibitor and vacant d-orbital of
metal atoms was proposed [2–4]. e adsorption of organic
inhibitors at the metal/solution interface takes place through
the replacement of water molecules by organic molecules
according to the following process [5]:
Org(sol) + 𝑥𝑥H2 O(ads) ⟶ Org(ads) + 𝑥𝑥H2 O
(1)
where Org(sol) and Org(ads) are organic molecules in the
solution and adsorbed on the steel surface, respectively, 𝑥𝑥
is the number of water molecules replaced by the organic
molecules. e Schiff base of cinnamaldehyde and panisidine gave 65% inhibition [6] in acid solutions at 55∘ C.
Other Schiff base compounds have offered better inhibition
than their amines and aldehydes [7–12]. Benzimidazole
molecule and their derivatives have been exploited as corrosion inhibitors, as the molecule has two anchoring sites
available for surface bonding which are the nitrogen atom
with its lonely sp2 electron pair and the aromatic rings [13–
16]. Triazoles, substituted triazoles adsorb on steel surfaces
and inhibit corrosion [17–19]. Substituted thioamides were
found to offer inhibition by forming Fe-inhibitor complex
on the surface [20]. e search for environmental friendly
corrosion inhibitor has resulted in the development of triazole derivatives [21]. e inhibition action of hydrazone
derivatives was performed via adsorption on the surface
obeying Frumkin adsorption isotherm [22].
In this paper, inhibitive action of BBH and PABH compounds on mild steel corrosion in 1 M HCl was studied
using weight loss study and electrochemical techniques. e
effect of temperature on the corrosion behaviour of mild steel
in 1 M HCl with optimum concentration of inhibitor was
studied in the temperature ranging 303–383 K.
2. Experimental Details
Mild steel coupons composed of 0.760% C, 0.019% Mn,
0.050% Cr, 0.026% Si, 0.012% P, 0.023% Al, 0.135% Cu,
0.050% Ni, and remainder being iron were used. Mild steel,
strips coated with lacquer with an exposed area of 1 cm2 were
used. BBH and PABH inhibitors were newly synthesized by
condensation of benzohydrazide with appropriate aldehydes.
ese compounds were characterized through their spectral
2
Journal of Chemistry
T 1: Names and structural formulae of compounds benzohydrazide derivatives.
Compound
Structure
Name and abbreviation
O
C
N
H
1
N� -benzylidene benzohydrazide (BBH)
N
HC
O
C
2
N
H
N� -(3-phenylallylidene) benzohydrazide (PABH)
N
T 2: Corrosion parameters derived from weight loss measurements in 1 M HCl containing N� -benzylidenebenzohydrazide
(BBH) at 303 K.
𝐶𝐶 (mM)
0.00
0.46
0.89
1.34
1.78
2.23
Surface
coverage
(𝜃𝜃)
—
0.89
0.93
0.95
0.96
0.97
Corrosion rate
(mmpy)
332.28
37.56
21.05
16.09
11.05
8.87
Inhibition
efficiency
(%)
—
88.69
93.66
95.15
96.52
97.32
T 3: Corrosion parameters derived from weight loss measurements in 1 M HCl containing PABH at 303 K.
𝐶𝐶 (mM)
0.00
0.40
0.80
1.20
1.60
2.00
Corrosion rate
(mmpy)
332.28
41.27
32.76
26.41
18.16
7.84
Surface coverage
(𝜃𝜃)
—
0.88
0.90
0.92
0.94
0.97
IE
(%)
—
87.57
90.24
92.04
94.53
97.43
T 4: Effect of 2.23 mM of BBH and 2.00 mM of PABH on corrosion in 1 M HCl at different temperatures (weight loss method)—1
hour immersion.
Temp. (K)
303
323
343
363
383
Corrosion rate (mmpy)
Blank
BBH
PABH
644.55
79.68
71.88
768.38
188.69
184.69
935.25
364.13
349.39
1222.85 648.36
581.21
1551.69 1008.44 935.51
IE (%)
BBH
PABH
87.6
88.84
75.45
76.03
61.06
62.64
49.43
52.47
34.97
38.54
data. eir purity was con�rmed by TLC. Table 1 presents the
structural formulae of these compounds.
A conventional three-electrode cell containing platinum
foil as counter electrode, saturated calomel electrode (SCE)
provided with the Luggin capillary as reference electrode,
and a mild steel specimen as working electrode were used.
Experiments were performed using EG & G Electrochemical analyzer (model 6310) at 303 K. Electrochemical
impedance spectroscopy measurements were carried out
between 100 kHz–10 mHz frequency range at steady open
circuit potential with an amplitude of 10 mV. e protective
�lm formed on the surface of the mild steel specimens was
investigated by SEM.
3. Results and Discussion
3.1. Weight Loss Studies. Corrosion inhibition efficiencies
(%) offered by N� -benzylidenebenzohydrazide at 303 K aer
3 hours immersion are given in Table 2. IE % was increased
with increase of concentration BBH. Table 3 presents the
% IE efficiency offered by N� -(3-phenylallylidene) benzohydrazide. 2.00 mM concentration of PABH has offered 97.43%
IE. Corrosion inhibition studies were carried out for different
temperatures aer immersing the steel specimens for an
hour. At different temperature studies, BBH and PABH
have offered good corrosion inhibition. However, the inhibition efficiencies were decreased with rise in temperatures
(Table 4). High inhibition efficiency of these compounds
were attributed to the presence of extensively delocalized 𝜋𝜋
electrons of the phenyl rings, planarity and the presence of
lone pair of electrons on N atoms, which favored greater
adsorption of BBH and PABH on the metal surface at 30 (...truncated)
