Controlling of H2 gas production during Zn dissolution in HCl solutions

Article abstract of DOI:10.1016/j.molliq.2017.10.035

Ethoxylated surfactants with different ethylene oxide units were synthesized and characterized using FTIR and ¹HNMR spectroscopy. The prepared compounds were evaluated as retarders towards the production of H₂ gas during the corrosio

Full text of DOI:10.1016/j.molliq.2017.10.035

Accepted Manuscript
Controlling of H2 gas production during Zn dissolution in HCl
solutions
S. Abd El Wanees, N.M. ElBasiony, A.M. Al-Sabagh, M.A.
Alsharif, S.M. Abd El Haleem, M.A. Migahed
PII:
S0167-7322(17)31147-9
doi:10.1016/j.molliq.2017.10.035
MOLLIQ 7996
DOI:
Reference:
To appear in:
Journal of Molecular Liquids
Received date:
Revised date:
Accepted date:
15 March 2017
1 July 2017
7 October 2017
Please cite this article as: S. Abd El Wanees, N.M. ElBasiony, A.M. Al-Sabagh, M.A.
Alsharif, S.M. Abd El Haleem, M.A. Migahed , Controlling of H2 gas production during
Zn dissolution in HCl solutions. The address for the corresponding author was captured
as affiliation for all authors. Please check if appropriate. Molliq(2017), doi:10.1016/
j.molliq.2017.10.035
This is a PDF file of an unedited manuscript that has been accepted for publication. As
a service to our customers we are providing this early version of the manuscript. The
manuscript will undergo copyediting, typesetting, and review of the resulting proof before
it is published in its final form. Please note that during the production process errors may
be discovered which could affect the content, and all legal disclaimers that apply to the
journal pertain.

ACCEPTED MANUSCRIPT
Controlling of H gas production during Zn
2
dissolution in HCl solutions
1
,2,
3
3
2
S. Abd El Wanees *, N. M. ElBasiony , A.M. Al-Sabagh , M.A. Alsharif , S. M.
1
3
Abd El Haleem and M. A. Migahed
1
Chemistry Department, Faculty of Science, Zagazig University, Zagazig 44519,
Egypt
2
Chemistry Department, Faculty of Science, University of Tabuk, Tabuk,
Saudi Arabia
3
Petroleum Applications Department, EPRI, Nasr City 11727, Cairo, Egypt
Abstract
Ethoxylated surfactants with different ethylene oxide units were
1
synthesized and characterized using FTIR and H NMR spectroscopy.
The prepared compounds were evaluated as retarders towards the
production of H gas during the corrosion of Zn in 0.5 M HCl. Different
2
chemical and electrochemical techniques were used. The surface
coverage and the inhibition efficiency was found to depend on the
surfactant type and its concentration. The inhibition effect was related to
the adsorption process, according to Freundlich model. The E-log i curves
proved that the used surfactants acted as mixed-type inhibitors. Some
thermodynamic and kinetics parameters were deduced and discussed.
Key words: Inhibitors; Zinc corrosion; EIS; AFM; Freundlich isotherm.
*
Corresponding author: s_wanees@yahoo.com
1
-Introduction:
Zinc is one of the most important metals used in the daily life. It has
several commercial applications, such as steel galvanization for corrosion
protection and as anode for chloride and alkaline batteries. The
1

ACCEPTED MANUSCRIPT
advantages come from its economic benefits, high capacity (0.82Ah/g),
rechargeable batteries and high discharge efficiency [1-3]. Some
researchers have taken great efforts in the production of H gas when
2
certain metals come in contact with acids [4-10]. The evolved hydrogen
gas accompanies the corrosion reaction was found to depend different
factors such immersion time, pH and temperature. The amount of the
produced H gas is retarded by the presence of corrosion products on
2
metal surface or/and corrosion inhibitors that decrease the exposed
surface area to the aggressive media [11].
Using of organic corrosion inhibitors represents a significant
endeavor to reduce the deteriorative effect of acidic media. Generally,
compounds that contain oxygen, sulfur and nitrogen are considered as
good corrosion inhibitors [12-14]. These compounds cover the
dissolution active sites of metal surface via the formation of an adsorbed
protective layer that protect the metal from the corrosive effect of the
medium.
Surfactant is considered as one of the most important type of
organic inhibitors owing to its impedance effect against the metal
corrosion via its surface activity and adsorption ability to form a
protective film. Moreover, surfactants have other merits such as eco-
friendly and easy to prepare [15-17]. The highest superior performance of
surfactants as corrosion inhibitors achieved near of its CMC that is
2

ACCEPTED MANUSCRIPT
regarded as the key attribute in the corrosion inhibition study [18, 19].
The inhibition activity of ethoxylated surfactants towards zinc corrosion
and H gas production in acidic media has been rarely investigated [20,
2
2
1]. So, the main goal of this study was to synthesis three novel nonionic
surfactants and investigate the mitigation effect towards zinc corrosion in
.5M HCl solution using chemical (hydrogen gas evolution) and
0
electrochemical (Tafel and EIS) techniques, complemented by surface
study using SEM and AFM.
2
2
-Experimental
.1. Preparation of ethoxylated nonionic surfactants
A mixture of dodecyl benzene sulfonic acid (LABS) and diethylene
triamine (DETA) in molar ratio 2:1, successively, was refluxed at 140°C
in the presence of xylene/ZnO. Mechanical stirring was continued until
dislodging an equivalent amount of H O forming the corresponding
2
sulfonamide. The solvent was removed and the sulfonamide was then
ethoxylated by insertion of ethylene oxide units (EO), according to
Wrigley method [22]. The reaction progress was followed by monitoring
the weight gain until the required number of EO units was obtained,
1
forming the desired surfactant, as shown in scheme 1. FTIR and HNMR
spectra, shown in Figs 1&2 are used to confirm the chemical structure of
the prepared surfactants.
3

ACCEPTED MANUSCRIPT
O
S
O
NH
O
NH
NH
S
O
0
.3 g Na
n
+
o
O
1
60 C
C12H25
C12H25
Ethylene oxide
Bis-(N-ethyl-p-dodecylbenzene sulphonamide]
(
CH -CH -O) -H
2 2
n
O
O
S
Xylene, Reflux
N
o
O
S
NH
(
140 C), 4hr
NH
O
2% ZnO
O
S
C12H25
O
OH
C12H25
N-Ethoxylateted (n)bis[N-ethyl-p-dodecyl benzene sulphonamide]
NH
2
+
H N
NH2
2
Compound I, n = 10
Compound II, n = 20
Compound III, n = 30
C12H25
LABS
DETA
Scheme 1. Synthesis of the ethoxylated surfactants.
2
.2. Materials and electrolyte
Specific pure Zn sheet (Johnson- Matthey, UK) was used to prepare
samples with dimensions 2cm x 5cm x 0.3cm for H gas evolution
2
method. For electrochemical measurements, Zn rods of the same
chemical composition were entrenched in epoxy resin with free surface
2
area of 0.28 cm , and used as working electrodes. The electrodes were
abraded, successively, with different grades of emery papers up to mirror
finish. For each run, the sample was washed with bi-distilled water
followed by rinsing with degreasing solvent and washing repeatedly with
4

ACCEPTED MANUSCRIPT
bi-distilled water and finally immersed in the test solution. A fresh 0.5 M
HCl solution was prepared using pure grade 37% HCl (BDH) and bi-
-
6
-4
distilled water. The required inhibitor concentrations (1x10 - 1x10 M)
below the CMC of surfactants were freshly prepared in 0.5 M HCl before
running the test.
2
.3. Experimental techniques
The volume of the collected H gas was calculated per unite area of
2
Zn specimen at different immersion times, using gasometric apparatus, as
reported before [8, 23, 24]. Volta lab 80 (PGZ 402) potentiostat with
Volta master 4 software was used to carry out the potentiodynamic
polarization and electrochemical impedance spectroscopy, EIS, under
static conditions, at 25°C. Three electrodes system with Zn rode as a
working electrode, a saturated calomel electrode, SCE, as a reference
electrode and Pt wire as a counter electrode. The potential/current curves
-1
were obtained by sweeping the electrode potential at 2 mVs from E
=
initial
-
1220 mV to Efinal = -800 mV. EIS curves were obtained by employing
5
frequency range of 1-10 Hz, and the amplitude was 10 mV peak to peak,
at the corrosion potential (Ecorr).
2
.4. Surface analysis
The surface morphology of Zn specimens was investigated before
and after soaking for 1hr in both of uninhibited (0.5 M HCl) and inhibited
5

ACCEPTED MANUSCRIPT
-
4
(
0.5 M HCl + 1x10 M compound III) solutions. Scanning electron
microscope (SEM, JEOL5300, Japan), at a magnification power X1000,
with an accelerated voltage of 25 kV and a working distance of 20 mm
and atomic force microscope (AFM, MFP-3D, Asylum Research, USA)
are used. The scan area was 25 µm by 25 µm.
3
3
. Results and discussion
.1. Corrosion inhibitors characterization
Fig 1 shows the FTIR spectrum of compound III as a representative
sample. The FTIR spectrum of compounds I and II afforded similar
spectra with a slight decrease of band’s intensity. Investigation of Fig 1
and the likes showed the following features: A strong broad band in the
−1
region of 3200–3600 cm assigns to OH stretching vibrations, while the
−1
strong band at 1200 cm points to CO ether stretching vibrations. The
−1
appearance of a band at 2922 cm is characteristic of CH aliphatic
confirming the incorporation of aliphatic moiety, while the weak band at
−1
1
1
455 cm corresponds to CN stretching vibration. The H-NMR
1
spectrum of the synthesized inhibitor (Fig 2) showed the HNMR
(
CDCl , δ PPM), 3.8 for H of – CH of repeated EO, 3.96, for H of – CH
3
2
2
of EO near the terminal –OH and (6.9-7.6) for H of aryl group.
6

ACCEPTED MANUSCRIPT
3
.2. Hydrogen production measurements
Measurements of the collected H gas produced from the dissolution
2
of Zn in 0.5 M HCl solution destitute of and containing different
additives gives an indication about the inhibitive effect of the ethoxylated
surfactant. Fig 3 shows the V-t curves for Zn in the absence and presence
of compound III. Similar curves were obtained with compounds I and II
(
curves not shown). It is clear that the presence of the ethoxylated
surfactant constringes the volume of the evolved H gas, due to the
2
reduction in the corrosion rate.
Generally, the overall corrosion reaction of Zn in acidic solutions
could be written as:
+
(aq)
+2
Zn + 2H
 Zn
+ H2(g)
(1)
(
s)
(aq)
which is the sum of anodic and cathodic reactions:
+
-
Zn(s)
 Zn
+ e
(2)
(3)
(4)
(5)
(aq)
+
(
+2
-
Zn
 Zn
+ e  H
+ e
aq)
(aq)
+
(
-
H
aq)
ads
H(ads) +H(ads)  H2(g)
Similar to Abd El Haleem et al. [23, 24] the rate of the evolved H2
gas can be determined from the slope of the volume-time relation. It is
7

ACCEPTED MANUSCRIPT
remarkable to see that, the H gas began to evolve after a specific period,
2
which is recalled incubation period. This period is required to destruct the
pre-immersion oxide film on metal surface by the aggressive ions [24].
The incubation period is delayed in presence of the inhibitor. Such
behavior could be attributed to the formation an adsorbed film by the
inhibitor. On the other hand, the rise in solution temperature will diminish
the incubation period, due to a reaction acceleration effect [25, 26].
Fig 4 represents the variation in the rate of H gas production, K ,
2
H
with the logarithm of inhibitor concentration, at 25°C. K values varies
H
with log C according to a straight-line relation, due to the adsorption of
inh
surfactant on Zn surface [23, 24].
The values of surface coverage, θ, and the inhibition efficiency, 
%
(Table 1) are calculated according to the equations [24]:
퐾H−퐾
H,inh
휃 = (
)
ꢀ6ꢁ
퐾H
퐾H−퐾
H,inh

% = (
) 100
ꢀ7ꢁ
퐾H
where K and K
are the rates of corrosion in case of blank and
H
H,inh
inhibitive solutions, respectively. Inspection of the data of Table 1 reveals
that:
8

ACCEPTED MANUSCRIPT
i-
Both the values of  and  % are increased with increasing
surfactant concentration, due to the increase in the number of
the adsorbed molecules on Zn surface. This reflects the
kindly inhibition effect of the used surfactants.
-
4
ii-
The maximum  % values in presence of 1x10 M of
surfactant were 68.2%, 81.2% and 87.2 %, successively,
with compounds I, II and III.
iii- The increases in the inhibition efficiency with increasing the
number of ethylene oxide units could be related to the
increase in the number of the interior O-atoms (ethylene
oxide units) which have ability to fix adsorbed molecules on
the surface of zinc metal[21].
iv- The mitigation of H gas production increased in the order:
2
compound I < compound II < compound III.
3
.3. Effect of temperature
The effect of temperature on the rates of Zn dissolution and H gas
2
production is further examined. The K values is increased with
H
+
temperature, as due to enhancement of the rate of diffusion of H ions to
metal surface [26]. The relative lowering in K values in presence of
H
9

ACCEPTED MANUSCRIPT
surfactant, confirms the mitigation of H gas production. The apparent
2
activation energy, E , can be calculated from Arrhenius equation [25, 26]:
a
−
퐸푎
ꢂꢃ = 퐴 exp ꢀ
ꢁ
ꢀ8ꢁ
푅푇
or
퐸푎
log ꢂ = log 퐴 ꢄ
ꢀ9ꢁ
ꢃ
2
.3ꢅ3푅푇
where, K is the rate of Zn dissolution or H gas production, A represents
H
2
the Arrhenius factor, T is the absolute temperature and R is the universal
-
1
gas constant (R = 8.314 J mol ).
However, the values of E can be determined mathematically from
a
-
1
Fig 5 (the relation between log K against T ) and are given in Table 2.
H
-
1
The obtained value of E for the blank solution is 24.4 kJ mol . In
a
-
4
presence of 1 x10 M surfactants the values of E are 45.1, 49.4 and 51.8
a
-
1
kJ mol with compounds I, II and III, successively. The rise in E values
a
could be attributed to the energy barrier of the formed film in presence of
surfactant. The variation in the E values of different compounds could be
a
attributed to the increase in the number of ethylene oxide units, EO [21,
2
2]. From the other point of view, the rise in E in the presence of
a
surfactants could be attributed to the physisorption process on Zn surface
27].
[
According to the transition state, the values of K at different
H
temperatures are used to locate the values of apparent enthalpy of
1
0

ACCEPTED MANUSCRIPT
activation, ΔH and entropy of activation, ΔS according to the following
a
a
equation [26–28]:
푅푇
ꢂꢃ =
푁ℎ
∆푆
−∆퐻푎
푅푇
푎
exp ( ) expꢀ
ꢁ
ꢀ10ꢁ
푅
where h is Planck’s constant, N is the Avogadro's number, and R is the
-1
universal gas constant. Plotting of log (K /T) against T gives a straight-
H
line relation, Fig 6. The data of this figure give a slope equal (-
∆
H /2.303R) and an intercept of [log (R/Nh ) + (∆S /2.303R)]. The values
a
a
of ΔH and ΔS were calculated and tabulated in Table 2. The positive
a
a
sign of ∆H in cases of free acid and inhibitor reflects the endothermic
a
nature of Zn dissolution. It means that the dissolution of Zn become
difficult in presence of the inhibitors [28, 29]. The higher values of ΔHa
and ΔE in presence of inhibitor than in a free solution indicate that the
a
energy barrier of corrosion reaction is increased in presence of surfactant
without altering the mechanism of corrosion [29]. However, the lower
values of -∆S in presence of surfactants confirm that the activated
a
complex is the rate determining step exemplifies a combination rather
than dissociation, i.e., less disordering takes place, on going from
reactants to the activated complex [30, 31].
3
.4. Adsorption behavior
1
1

ACCEPTED MANUSCRIPT
The inhibition influence of the ethoxylated surfactants on Zn
dissolution reaction in 0.5M HCl solutions was related to their ability to
adsorb on Zn surface. Surface coverage, θ, assessed from the data of KH
values are used as a function of inhibitor concentration, to investigate the
type of adsorption. The isotherm explicates the nature of interaction
between metal and inhibitor molecules. Different adsorption isotherms
are attempted, the best fit was found to obey Freundlich type. According
to this isotherm, the relation between the two variables C and θ can be
inh
represented by [32]:
ꢇ
log 휃 = log ꢂꢆ푑푠 + log 퐶
ꢀ11ꢁ
ꢈ푛ℎ
푛
The graphical representation of this equation, Fig 7, gives straight line
2
with linear correlation coefficient (r ) equal one. According to equation
1
1, K is the adsorption equilibrium constant, and 1/n is the Freundlich
ads
slope, which is a measure of adsorption intensity or surface heterogeneity.
When 1/n value lies in range > 0 and < 1 indicates a favorable and strong
adsorption condition. While, when 1/n value is > 1 the adsorption become
weak and not favorable [33-35]. In our study, the 1/n is ~ 0.1, Table 3,
which indicates a favorable adsorption process.
Kads is used to calculate the standard free energy of
adsorption, ΔG° , using the equation [36]:
ads
1
2

ACCEPTED MANUSCRIPT
ꢇ
ꢂads = 5 expꢀ
5.5
−∆퐺°
ꢉꢊꢋ
ꢁ
ꢀ1ꢌꢁ
푅푇
where 55.5 is the molar concentration value of H O and R is the universal
2
gas constant. The calculated values of K and ΔG° are recorded
ads
ads
in Table 3. The negative sign of ΔG° secures the spontaneity of the
ads
adsorption process and fastness of the adsorbed film on Zn surface.
-
1
Really, when ΔG° values around -40 kJ mol or more negative alludes
ads
-
1
to the chemisorption type, while those around -20 kJ mol or less
negative are correlating to physical adsorption [37, 38]. In our case, the
-
1
obtained ΔG°ads values are varied between -11.49 and -12 kJ mol ,
which possibly articulate that the physical adsorption is likely to
predominate[37, 38].
3
.5. Polarization study.
The E-log i potentiodynamic polarization curves for Zn in 0.5 M
HCl destitute of and containing different additions of compound III are
depicted in Fig 8. Similar curves are obtained in case of compounds I and
II (curves not shown). It is clear that, the cathodic and anodic curves are
suppressed in case of inhibitive solution, as due to the increase in the
overvoltage of each of cathodic and anodic processes. This behavior
could prove that the mechanism of H evolution is under activation-
2
controlled process, and both the mechanism of H evolution and Zn
2
dissolution are not altered by presence of inhibitor [28, 29].
1
3

ACCEPTED MANUSCRIPT
The surface coverage, θ, and the inhibition efficiency ' %, are
calculated from the equations [39, 40]:
퐼cꢍrr−퐼cꢍrr,inh
휃 = (
)
ꢀ1ꢎꢁ
ꢀ14ꢁ
퐼cꢍrr
−퐼cꢍrr,inh

′% = ꢀ퐼cꢍrr
ꢁ100
퐼cꢍrr
where Icorr and Icorr, inh are the corrosion current densities of Zn in 0.5 M
HCl without and with inhibitor, respectively. Table 4 displayed the
electrochemical corrosion parameters, viz., corrosion potential
(
E ), corrosion current density (I ), anodic Tafel slopes (β ), cathodic
corr
corr
a
Tafel slopes (β ) and the percentage of inhibition efficiency (' %) for the
c
used surfactants in 0.5 M HCl. Inspection of the data of Table 4 reveals
that, both the values of  and  % increase with increasing surfactant
concentration and follow the order: compound I < compound II <
compound III, as due to the increase in the number of EO units in the
ethoxylated surfactant [21].
In addition, the non-significant changes in the values of β and β ,
a
c
beside the little displacement in Ecorr (7-28 mV ), which less than 85
SCE
mV, prove that the ethoxylated compounds acted as mixed-kind inhibitors
[
41-44].
.6. Electrochemical impedance spectroscopy EIS Measurements.
3
1
4

ACCEPTED MANUSCRIPT
Fig 9 depicts the Nyquist plots for Zn in 0.5 M HCl destitute of and
containing different concentrations of compound III. Similar plots are
obtained in case of compounds I and II (curves not shown). The obtained
data in all studied frequency range, clarifies that, the presence of
surfactant increase the diameter of the capacitive loops, without altering
their shapes. This behavior indicates that the used surfactant introduce
an inhibitive film that impedes the corrosion of Zn in HCl[45]. The
presence of non perfect semicircles can be referred to the frequency
dispersion effect, as well as, the presence of non homogenous surface
and mass transfer resistant [45, 46].
To analyze the impedance spectra of the Nyquist plots, the
equivalent circuit model shown in Fig.10 are used. The equivalent circuit
was consists of the solution resistance (R ) shorted by a constant phase
s
element, CPE, which is connected in parallel to charge transfer resistance
(
R ).
ct
The increase in R values in presence of inhibitor confirms
ct
retardation of Zn dissolution and hydrogen evolution reaction. The value
Rct was directly proportional with ethoxylation degree, as well as, the
inhibitor concentration [46, 47]. The values of electrical double layer
capacitance, C , vary with R according to the relation:
dl
ct
ꢇ
Cdꢏ = ꢀ2
ꢁ
ꢀ1ꢑꢁ
πfmꢉꢐRct
1
5

ACCEPTED MANUSCRIPT
where fmax is the frequency at maximum imaginary impedance.
The values of C , were reduced in presence of surfactant and
dl
become much lower, as the number of EO units is increased in the
surfactant molecule. This could be pointed to the increase in the thickness
of the electrical double layer around the protective film and/or decrease
the local dielectric constant due to the replacement of water molecules at
the electrode surface by adsorbed inhibitor molecules [48].
Also, the reduction in C in presence of surfactant is inversely
dl
proportional to the double layer thickness, , according to Helmholtz
model[49].
휀휀°푆
퐶푑푙 = ( 훿
)
ꢀ16ꢁ
°
where S is the electrode surface area, ε is the dielectric constant and ε is
the air permittivity. The lower values of C in the presence of surfactant
dl
may be resulted from the effective adsorption of the surfactants. This fact
suggests that the inhibitor molecules may firstly adsorbed on Zn surface,
covering the active sites.
The value of inhibition efficiency,'' %, are obtained from Rct
values, using the equation [46]:
푅 −푅ꢒ
′′% = ( ct
ct
) 100
ꢀ17ꢁ

푅ct
1
6

ACCEPTED MANUSCRIPT
where the values of R and R' are the electric charge transfer resistance
ct
ct
for Zn in 0.5 M HCl in the presence and absence of inhibitor,
-4
respectively. The values of ''%, Table 5, in presence of 1x10 M of
compounds I, II and III, are 72.0%, 78.0 % and 82 %, successively. This
behavior reflects that the inhibition efficiency increases in the order:
compound I < compound II < compound III. This conclusion confirms
the agreement between the results obtained by EIS and other techniques.
The corresponding phase angle and Bode impedance plots depicted
for Zn in 0.5 M HCl with and without different additions of compound III
are shown in Figs 11 & 12, respectively. The data of Bode plots, Fig 11,
indicted that, at lower frequencies Zmod increases as the surfactant
concentration is increased. This behavior is attributed to the higher
protection as due to the adsorption process [51]. In the phase angle plots,
Fig 12, the increase in the concentration of surfactant shifts the phase
angle into more negative values, elucidating an excellent inhibitive
implementation, as due to the adsorption of more inhibitor molecules on
Zn surface.
3
.7. Inhibition mechanism
The inhibitive action of surfactant, DS, is supposed to be related to its
adsorption through the active sites on Zn/HCl interface to form a
preservative film. This film shields the metal surface from the corrosive
1
7

ACCEPTED MANUSCRIPT
medium. The adsorption of DS molecules at Zn/HCl water interface can
be regarded as a replacement process between DS molecules in the
aqueous solution, DS , and water molecules on the metallic surface,
sol
H O
2
ads
DS + x H O
DS + x H O
(18)
sol
2
ads
ads
2
sol
where x is the number of water molecules replaced by a molecule of
DS . DS molecules can adsorb on the Zn surface via N and O atoms
sol
sol
without ignoring the effective role of π-electrons of aromatic ring.
Moreover, the high molecular weight of DS molecules enhances the
adsorption process.
From the second point of view, the inhibition mechanism can also
be explained by Zn-DS intermediate formed at the anodic and cathodic
ads
-
sites. The DS molecules interact with ZnCl , electrostatically, so the
ads
ads
oxidation of Zn to form ZnCl can be tolerated. In addition, since the
2
+
discharge of H ions to form adsorbed H atoms on Zn surface is the rate-
determining step, the adsorption of efficient DS molecules will almost
+
cover the surface leading to retardation of discharge of H ions.
-
+
-
+
ZnCl + DSH
(ZnCl DSH )
(at anodic site) (19)
(20)
ads
ads
-
+
+
-
ZnCl + DSH
(ZnDSH ) + Cl
ads
ads
+
-
Zn + H + e
ZnHads
(at cathodic site) (21)
1
8

ACCEPTED MANUSCRIPT
+
-
+
Zn+ DSH + e
(ZnDSH )
(22)
(23)
ads
ZnH + ZnH
Zn + H2
ads
ads
At lower concentrations the adsorbed inhibitor, ZnDS(ads) is more soluble
and its concentration is not enough to cover the Zn surface. So, the
corrosion process takes place on the sites free from ZnDS . When
(ads)
DS(sol) concentration is high enough, a compact and coherent inhibitor
layer is formed on Zn surface, reducing the corrosion process.
4
4
. Surface morphology.
.1. Scanning electron microscopy (SEM)
Fig 13A, displays the SEM micrograph of the polished Zn surface
before immersion in the test solution. Only, it shows some scratching
lines, due to polishing process. The destructive effect of HCl on the
polished Zn samples after immersion for a period of 1hr in 0.5 M HCl
-
4
devoid of and containing 1x10 M of compound III is examined,
successively Figs 13(B&C). In the free acid solution Fig 13B, the Zn
surface appears to be highly damaged. The protective effect of the
inhibitor appears strikingly, Figs 13C, where, the aggressive action of
HCl on Zn surface was highly mitigated. In addition to that some the
scratching lines were covered with the corrosion products formed on Zn
surface.
4
.2. AFM surface morphology
1
9

ACCEPTED MANUSCRIPT
AFM is considered as a potent technique in the morphological
investigation of metal surface at nano-to micro scale, mainly in three-
dimensions (3D). So, AFM can be used to evaluate the activity of the
corrosion inhibitor via the calculation of the surface roughness parameter
for specific surface area. The 3D images acquired for Zn surface before
and after immersion for a period of 1hr, in blank and inhibited solutions
are depicted in Figs 14(B&C), successively. The average roughness of
Zn pattern before immersion in 0.5M HCl, Fig 14A, represents AFM
image for the abraded Zn surface with average roughness 4.080 nm. Fig
1
4B, for Zn in 0.5M HCl, shows the highly damaged and potholed
surface with highest surface roughness value of 14.692 nm. Fig 14C
-4
displays AFM of Zn surface after immersion in 0.5M HCl + 1x10 M of
compound III. The surface is seen to be more even and less damaged with
lower average roughness of 9.700 nm. The reduction in the average
surface roughness in the inhibited solution relative to blank indicates the
inhibition action of the ethoxylated surfactants, via the formation of an
adsorbed protective film, making the surface more even and uniform.
5
. Conclusions
1
. The rate of H production increases with the immersion time and
2
the solution temperature.
2
. Small additions of surfactants decrease the corrosion rate as
confirmed from the data of Tafel and EIS techniques.
2
0

ACCEPTED MANUSCRIPT
3
4
. Polarization data indicates that the surfactants are mixed inhibitors.
. The inhibition efficiency is increased with increase the
ethoxylation degree and the concentration of the surfactants, but
decrease with the temperature rise.
5
6
. The adsorption process physically obeys Freundlich isotherm.
. The inhibition activity of different compounds increases in the
order: I < II < III.
6
. References
[
1]O. Abootalebi, A. Kermanpur, M. R. Shishesaz, M. A. Golozar.
Optimizing the electrode position in sacrificial anode cathodic protection
systems using boundary element method, Corros. Sci., 52(2010) 678-687.
[
2] S. Manov, F. Noli., A. M. Lamazouere, L. Aries, Surface treatment
for zinc corrosion protection by a new organic chelating reagent, J. Appl.
Electrochem., 29(1999) 995-1003.
[3] F. Wang, F. Yu, X. Wang, Z. Chang, L. Fu, Y. Zhu, Z. Wen, Y.Wu,
W. Huang, Aqueous rechargeable zinc/aluminum ion battery with good
cycling performance, ACS Appl. Mater. Interfaces, 14 (2016) 9022–
9
029.
[
4] S.H. Yu, J.Y. Uan, H.T. Lin, Effects of concentrations of NaCl and
organic acid on generation of hydrogen from magnesium metal scrap, Int.
J. Hydrogen Energy, 37 (2012)3033-3040.
[
5] L. Soler, A.M. Candela, J. Macana´s, M. Muñoz, J. Casado,
Hydrogen generation by aluminum corrosion in seawater promoted by
suspensions of aluminum hydroxide, Int. J. Hydrogen Energy, 34
(
2009)8511- 8518.
[
6]A. K. Vijh, G. Be´langer, R. Jacques, Electrochemical activity of
silicides of some transition metals for the hydrogen evolution reaction in
acidic solutions, Int. J. Hydrogen Energy, 15(1990)789-794.
2
1

ACCEPTED MANUSCRIPT
[
7] E. Czech, T. Troczynski, Hydrogen generation through massive
corrosion of deformed aluminum in water, Int. J. Hydrogen Energy, 35
(
2010)1029-1037.
[
8]M.A. Deyab, Effect of halides ions on H production during aluminum
2
corrosion in formic acid and using some inorganic inhibitors to control
hydrogen Evolution, J. Power Source, 242 (2013)86-90.
[
9] L. Soler, A.M. Candela, J. Macanás, M. Muñoz, Hydrogen
generation from water and aluminum promoted by sodium stannate, Int.
J. Hydrogen Energy, 35(2010)1038-1048.
[
10] J-Y. Uan, S-H. Yu, M-C. Lin, L-F. Chen, H-I. Lin, Evolution of
hydrogen from magnesium alloy scraps in citric acid-added seawater
without catalyst, Int. J. Hydrogen Energy, 34 (2009)6137- 6142.
[11] M. A. Deyab, Hydrogen generation during the corrosion of carbon
steel in crotonic acid and using some organic surfactants to control
hydrogen evolution, Int. J. Hydrogen Energy, 38(2013) 13511-13519.
[
12] A. Popova, Temperature effect on mild steel corrosion in acid media
in presence of azoles, Corros Sci.,49 (2007) 2144-2158.
[
13] S. L. Granese, B. M. Rosales, C. Oviedo, J. O. Zerbino, The
inhibition action of heterocyclic nitrogen organic compounds on Fe and
steel in HCl media, Corros. Sci., 33(1992)1439-1453.
[
14] G. Subramanian, K. Balasubramanian, P. Sridhar, 1,1′-Alkylene bis-
pyridinium compounds as pickling inhibitors, Corros. Sci., 30(1990)
019-1023.
1
[
15]M. A. Deyab, S. S. AbdEl-Rehim, On surfactant–polymer association
and its effect on the corrosion behavior of carbon steel in cyclohexane
propionic acid, Corros. Sci., 65(2012) 309-3016.
[
16] J. Zhu, Y. Zhou, C.Gao, Influence of surfactants on electrochemical
behavior of zinc electrodes in alkaline solution, J. Power Sources, 72
1998) 231-235.
(
2
2

ACCEPTED MANUSCRIPT
[
17] M. A. Deyab, Hydroxyethyl cellulose as efficient organic inhibitor of
zinc-carbon battery corrosion in ammonium chloride solution-Electroche-
mical and surface morphology studies, J. Power Sources, 280(2015)190-
1
94.
[
18]A. M. Alsabagh, M.A. Migahed, H.S. Awad, Reactivity of polyester
aliphatic amine surfactants as corrosion inhibitors for carbon steel in
formation water (deep well water), Corros. Sci., 48 (2006)813-828.
[
19] M. A. Migahed, M. Abd-El-Raouf M, A.M. Al-Sabagh, H.M. Abd-
El-Bary, Effectiveness of some non ionic surfactants as corrosion
inhibitors for carbon steel pipelines in oil fields, Electrochim. Acta,
5
0(2005) 4683-4689.
[20]E. E. Foad El –Sherbini, S. M. Abd El Wahaab and M. A. Deyab,
ethoxylated fatty acids as inhbitors for the corrosion of zinc in acid
media, Mater. Chem. Phys., 89 (2005)183-191.
[
21]M. Abdalla, Ethoxylated fatty acids as corrosion inibitors for
dissolution of zinc in hydrochloric acid, Corros. Sci., 89(2003) 2705-
716.
2
[
22] A.N. Wrigley, F. D. Smith, A. J. Stirton, Synthetic detergents from
animal fats.VIII. The ethenoxylation of fatty acids and alcohols, J. Am.
Oil Chem. Soc., 34(1957) 39-43.
[23] E. E. Abd El Aal, S. Abd El Wanees, A. Farouk, S.M. Abd El
Haleem, Factors affecting the corrosion behavior of aluminium in acid
solutions. II. Inorganic additives as corrosion inhibitors for Al in HCl
solutions, Corros. Sci., 68 (2013) 14-24.
[
24] S.M. Abd El Haleem, S. Abd El Wanees, E. E. Abd El Aal, A.
Farouk, Factors affecting the corrosion behavior of aluminium in acid
solutions. I. Nitrogen and/or sulphur-containing organic compounds as
corrosion inhibitors for Al in HCl solutions, Corros. Sci., 68 (2013) 1-13.
[
25]S. Abd El Wanees, A. B. Radwan, M. A. Alsharif, S. M. Abd El
Haleem, Initiation and inhibition of pitting corrosion on reinforcing steel
under natural corrosion conditions, Mater. Chem. Phys., 190(2017)79-95.
2
3

ACCEPTED MANUSCRIPT
[
26] S. Abd El Wanees, M. I. Alahmdi, M. Abd El Azzem, H. E. Ahmed,
4
,6-Dimethyl-2-oxo-1,2-dihydro-pyridine-3-carboxylic acid as an
inhibitor towards the corrosion of C-steel in acetic acid, Inter. J.
Electrochem. Sci., 11 (2016) 3448 – 3466.
[
27] M.H.M. Hussein, M. F. El-Hady, H. A. H. Shehata, M. A. Hegazy,
H. H. H. Hefni, Preparation of some eco-friendly corrosion inhibitors
having antibacterial activity from sea food waste, J. Surfact. Deterg., 16
(2013) 233-242.
[28] S. Abd El Wanees, M. I. Alahmdi, S.M. Rashwan, M. M. Kamel,
and M.G. Abd Elsadek, Inhibitive effect of cetyltriphenylphosphonium
bromide on C-steel corrosion in HCl solution, Inter. J. Electrochem. Sci.,
1
1 (2016) 9265 – 9281.
[29]S. A. Umoren, M. M. Solomon, U. M. Eduok, I. B. Obot, A. U.
Israel, Inhibition of mild steel corrosion in H SO solution by coconut
2
4
coir dust extract obtained from different solvent systems and synergistic
effect of iodide ions: Ethanol and acetone extracts, J. environ. Chem.
eng., 2 (2014)1048-1060.
[30] C. Verma, E. E. Ebenso, Y. Vishal, M.A.Quraishi, Dendrimers: A
new class of corrosion inhibitors for mild steel in 1 M HCl: Experimental
and quantum chemical studies, J. Mol. Liq., 224(2016) 1282-1293
[31] M. Faustin, A. Maciuk, P. Salvin, C. Roos, M. Lebrini, Corrosion
inhibition of C38 steel by alkaloids extract of Geissospermum laeve in 1
M hydrochloric acid: Electrochemical and phytochemical studies, Corros.
Sci., 92 (2015) 287-300.
[
32] M.A. Deyab, R. Essehlib, B. El Balic, Inhibition of copper corrosion
in cooling seawater under flowing conditions by novel pyrophosphate,
RSC Adv., 5(2015) 64326-64334.
[
33]M. R. Gandhi, N. Viswanathan, S. Meenakshi, Preparation and
application of alumina/chitosan biocomposite, Int. J. Biol. Macromol., 47
2010) 146–154.
(
2
4

ACCEPTED MANUSCRIPT
[34]M. El Ouardi, S. Alahiane, S. Qourzal, A. Abaamrane, A. Assabbane,
A. Douch, Removal of carbaryl pesticide from aqueous solution by
adsorption on local clay in Agadir, Am. J. Analyt. Chem. 4(2013) 72-79.
[35] W. T. Tsai, Y. M. Chang , C. W. Lai, C. C. Lo, Adsorption of basic
dyes in aqueous solution by clay adsorbent from regenerated bleaching
earth, Appl. Clay Sci., 29(2005) 149– 154.
[36] S. M. Hassan, Y.A. Elawady, A.I. Ahmed, A.O. Baghlaf, Studies on
the inhibition of aluminium dissolution by some hydrazine derivatives,
Corros. Sci., 19 (1979)951-659.
[
37] M.M. Solomon, S.A. Umoren, I.I. Udosoro, A.P. Udoh, Inhibitive
and adsorption behavior of carboxymethyl cellulose on mild steel
corrosion in sulphuric acid solution, Corros. Sci., 52 (2010) 1317-1325.
[
38]A. A. Gürten, K. Kayakırılmaz, M. Erbil, The effect of
thiosemicarbazide on corrosion resistance of steel reinforcement in
concrete, Constr. Build. Mater., 21(2007)669-676.
[
39]M. A. Ameer, A. M. Fekry, Inhibition effect of newly synthesized
heterocyclic organic molecules on corrosion of steel in alkaline medium
containing chloride, Int. J. hydrogen energy, 35 (2010)11387-11396.
[
40]M. A. Amin, M. A. Ahmed, H. A. Arida, T. Arslan, M. Saracogiu, F.
kandemirli, Monitoring corrosion and corrosion control of iron in HCl by
non-ionic surfactants of the TRITON-X series–Part II. Temperature
effect, activation energies and thermodynamics of adsorption, Corros.
Sci., 53 (2011)540-548.
[
41] E. E.Oguzie, Corrosion inhibition of aluminium in acidic and
alkaline media by Sansevieria trifasciata extract, Corros. Sci., 49 (2007)
527-1539.
1
[
42]C.B. Shen, S.G. Wang, H.Y.Yang, K. Long, F.H.Wang, The
adsorption stability & inhibition by allyl-thiourea of bulk nanocrystalline
ingot iron in dilute HCl solution, Appl. Surf. Sci., 253 (2006)2118-2122.
2
5

ACCEPTED MANUSCRIPT
[
43] A. K. Singh, Inhibition of mild steel corrosion in hydrochloric acid
solution by 3-(4-((Z)-indolin-3-ylideneamino)phenylimino)indolin-2-one,
Ind. Eng. Chem. Res., 51(2012)3215- 3223.
[44]W. Li, Q.He, C. Pei, B. Hou, Experimental and theoretical investigation
of the adsorption behaviour of new triazole derivatives as inhibitors for
mild steel corrosion in acid, Electrochim. Acta, 52 (2007) 6386–6394.
[
45]N. Labjar, M. Lebrini, F. Bentiss, N. Chihib, S. El Hajjaji, C. Jama,
Corrosion inhibition of carbon steel and antibacterial properties of
aminotris-(methylenephosphonic) acid, Mat. Chem. Phys., 119 (2010)
3
30–336.
[
46] H. Ashassi-Sorkhabi, N. Ghalebsaz-Jeddi, F. Hashemzadeh, H.
Jahani, Corrosion inhibition of carbon steel in hydrochloric acid by some
polyethylene glycols, Electrochim. Acta, 51(2006) 3848-3858.
[47]J. A. Syed, S. Tang, H. Lu, X. Meng, Water-soluble polyaniline-
polyacrylic acid composites as efficient corrosion inhibitors for 316SS,
Ind. Eng. Chem. Res., 54 (2015) 2950−2959.
[
48]I. Sekine, M. Sabongi, H. Hagiuda, T. Oshibe, M. Yuasa, T. Imahma,
Y. Shibata, T. Wake, Corrosion inhibition of mild steel by cationic and
anionic polymers in cooling water system, J. Electrochem. Soc., 139
(
1992)3167-3173.
[
49] B. S. Sanatkumar, J. Nayak, A. N. Shetty, Influence of 2-(4-
chlorophenyl)-2-oxoethyl benzoate on the hydrogen evolution and
corrosion inhibition of 18 Ni 250 grade weld aged maraging steel in 1.0
M sulfuric acid medium, Int. J. Hydrogen Energy, 37 (2012) 9431–9442.
[
50] M. A. Hegazy, M. Badawi, S.S. Abd El Rehim, W. M. Kamel,
Corrosion inhibition of carbon steel using novel N-(2-(2-
mercaptoacetoxy)ethyl)-N,N-dimethyl dodecan-1-aminium bromide
during acid pickling, Corros. Sci., 69 (2013) 110–122.
[51]H. H M. Abd El-Lateef, A.M. Abu-Dief, M. A.A. Mohamed,
Corrosion inhibition of carbon steel pipelines by some novel Schiff base
compounds during acidizing treatment of oil wells studied by
2
6

ACCEPTED MANUSCRIPT
electrochemical and quantum chemical methods, J. Mol. Struct.,
1
130(2016)522-542.
2
7

ACCEPTED MANUSCRIPT
2
8

ACCEPTED MANUSCRIPT
2
9