Urine ( CU ) add-on was evaluated at five different temperatures in the scope from 30-70 C by weight loss measurings. CU acts as a good inhibitor for the corrosion of mild steel in 1.5 M H2SO4. The
value of suppression efficiency additions with increasing both inhibitor concentration and solution
temperature. Approach: The surface assimilation of CU components on the mild steel surface obeys the
Langmuir surface assimilation isotherm proposing a monolayer surface assimilation of CU species. Thermodynamic
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parametric quantities for CU surface assimilation and mild steel corrosion were evaluated. The negative values of ( DGoads )
stress the spontaneousness of the surface assimilation procedure and stableness of the adsorbed bed. Consequences: The
estimated high, positive value of DHoads ensures that CU species is adsorbed chemically on mild steel
surface. All values of E*
app for mild steel corrosion in inhibited solutions were lower than that for the
uninhibited solution bespeaking the happening of chemosorption mechanism. Decision: The surface
morphology of mild steel in absence and presence of inhibitor revealed that with increasing both CU
concentration and solution temperature, mild steel surface is modified and looks smooth. Good
correlativity between the inhibitor components and its repressive action was obtained.
Cardinal words: Corrosion, thermodynamic, chemosorption, sulphuric acid, environmentally friendly
inhibitor, inhibitor components, natural inhibitors, works resources, non-toxic, reaction
invariables, natural merchandises
Introduction
Etre, 2006 ) , artemisia oil ( Benabdellah et al. , 2006 ) ,
Zenthoxylum alatum infusion ( Chauhan and
Corrosion control of metals is an of import activity Gunasekaran, 2007 ) , Fenugreek Leaves infusion ( Noor,
of proficient, economical, environmental and aesthetical 2007 ) , Justicia gendarussa ( Satapathy et al. , 2009 ) have
importance. Therefore, the hunt for new and efficient been reported to be good inhibitors for steel in acid
corrosion inhibitors has become a necessity to procure solutions. As noticed, all the old natural inhibitors
metallic stuffs against corrosion. Over the old ages, were obtained from works resources. In recent plants
considerable attempts have been deployed to happen suited ( Noor, 2004 ; 2008 ) , Camel s Urine ( CU ) obtained from
compounds of organic beginning to be used as corrosion animate being beginning was reported as corrosion inhibitor for
inhibitors in assorted caustic media, to either halt or mild steel in HCl solutions. Camel s piss can be
detain the maximal onslaught of a metal ( Umoren et al. , classified as environmentally friendly inhibitor, because
2008 ) . However, the known jeopardy effects of most microbiological survey on CU proved its high efficiency
man-made organic inhibitors and the demand to develop against a figure of infective bugs when
inexpensive, non-toxic and environmentally benign procedures compared with some antibiotics. Furthermore, the
hold now made research workers to concentrate on the usage of effectual component of CU was isolated and tested as
natural merchandises. These natural organic compounds are antineoplastic agent which is labeled as PM 701 ( Moshref
either synthesized or extracted from aromatic herbs, et al. , 2006 )
spices and medicative workss. By and large talking, inhibitors are found to protect
Recently, assorted natural merchandises from works steel corrosion in acerb solutions by adsorbing onto
beginnings e.g. , Zenthoxylum-alatum fruits extract steel surface. Adsorption isotherms such as Langmuir
( Gunasekaran and Chauhan, 2004 ) , Telfaria ( 1917 ) surface assimilation isotherm, surface assimilation isotherm,
Occidentalis infusion ( Oguzie, 2005 ) , Khilla infusion ( El-Flory ( 1942 ) and Huggins ( 1942 ) surface assimilation isotherm
Matching Writer:
Ehteram A. Noor, Department of Chemistry, Science Faculty for Girls, King Abdulaziz University,
Jeddah, Saudi Arabia Tel: +00966 ( 0505537707 ) Facsimile: +00966 ( 022652112 )
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Am. J. Applied Sci. , 8 ( 12 ) : 1353-1362, 2011
and Frumkin ( 1964 ) surface assimilation isotherm are used to
clarify the suppression mechanism of inhibitors. If
the surface assimilation isotherm for a given inhibitor is
specified at different temperatures, thermodynamic
parametric quantities for the surface assimilation procedure would be
estimated, giving a good aid to propose the
suppression mechanism. Furthermore the thermodynamic
activation parametric quantities for the corrosion procedure are
besides of import to explicate the surface assimilation phenomenon
of inhibitor.
In the present survey the writers attempt to analyze the
repressive action of CU for mild steel corrosion in 1.5M
H2SO4 at five different temperatures ( 30-70 C ) by
utilizing weigh loss method. Assorted thermodynamic
parametric quantities for inhibitor surface assimilation every bit good as for mild
steel corrosion in absence and presence of different
concentrations of CU were estimated and discussed.
MATERIALS AND METHODS
Specimens: The experiments were performed with mild
steel rods of the undermentioned composing ; C: 0.250, Mn:
0.480, Si: 0.300, Ni: 0.040, Cr: 0.060, Mo: 0.020, S:
0.021, P: 0.019 and the balance is Fe.
Inhibitor: The camel s urine sample is extracted from
female camel ( one humped ) with age around 4-5 old ages,
early in the forenoon. Physically, the fresh extracted
urine appears clear, amber xanthous and watery.
Solutions: The aggressive solution ( 1.5M H2SO4 ) was
prepared by dilution of analytical class reagent with
deionized H2O. The needed concentrations ( 1, 2, 6,
10 and 14 v/v % ) of inhibitor were prepared by thining
with 1.5 M of H2SO4 solutions.
Corrosion rate measurings: Weight loss method
was employed for mild steel corrosion rate
measurings in absence and presence of assorted
concentrations of CU at different temperatures. Prior to
each experiment, the mild steel specimen of 1.0 centimeters in
diameter and 5.0 centimeter in length was abraded with a series
of emery survey from 220-1000 classs. Then, it was
washed several times with deionized H2O so with
ethyl alcohol and dried utilizing a watercourse of air. After weighing
accurately, it was immersed in 100 milliliter flask, incorporating
50 milliliter of solution. After 90 min, the specimen was
taken out, washed, dried and weighed accurately. The
trial was performed in absence and presence of different
inhibitor concentrations and different temperatures ( 3070
C ) . The rate of weight loss was calculated ( rWL, milligram
cm.2 min.1 ) as follows Eq. 1:
W – Tungsten
rWL = 1 2 ( 1 )
S.t
Where:
W1 and W2 = The specimen weight before and after
submergence in the tried solution
S = The surface country of the specimen
T.
= The terminal clip of each experiment
The corrosion rates in the absence ( roWL ) and
presence ( rWL ) of an inhibitor are used to measure its
suppression efficiency by utilizing the undermentioned Eq. 2:
IE % = ( 1 -r
owl ) 100 ( 2 ) rWL
Surface morphology surveies: Characteristic characteristics
of mild steel surface after submergence in 1.5 M H2SO4
in absence and presence of low ( 1 % ) and high ( 10 % )
concentrations of CU at 30 and 70 C were
investigated by optical micrographs utilizing microscope
of the type ( Leitz METALLUX3 microscope
WETZLAR, Germany ) .
Consequence
Table 1 represents the corrosion rates of mild steel
in 1.5 M of H2SO4 solution in absence and presence of
assorted concentrations of CU ( 1-14 milliliter % ) .
Figure 1 show the relationship between logr and
logCinh at different temperatures which is in conformity
with the undermentioned Eq. 3 ( Noor and Al-Moubaraki, 2003 ) :
log r= log r+ Blog C isoniazid
( 3 )
Where:
Cinh = The concentration of the inhibitor
R = The corrosion rate when the concentration of
inhibitor becomes unity
B = A invariable for the studied reaction
Table 1: Mild steel corrosion rates in 1.5 M H2SO4 in absence
and presence of different concentrations of CU at different
temperatures
Corrosion rate 105 ( g cm-2 min-1 )
Cinh ( mL % ) 30 40 50 60 70
0 0.739 2.295 4.483 12.294 31.22
1 0.493 0.750 1.505 2.001 3.408
2 0.459 0.627 0.912 1.112 1.743
6 0.241 0.249 0.418 0.572 0.853
10 0.156 0.177 0.241 0.467 0.637
14 0.134 0.126 0.176 0.203 0.303
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Table 2: Kinetic parametric quantities ( B, R and r2 ) for mild steel corrosion in
1.5M H2SO4 solution incorporating CU at different
temperatures
2
T ( oC ) -B R ( g cm-2 min-1 )
R
30o 0.5 0.564 0.96
40o 0.7 0.847 0.98
50o 0.8 1.574 0.99
60o 0.8 2.028 0.94
70o 0.8 3.381 0.96
Fig. 1: Dependence of mild steel corrosion rate on the
concentration of CU in 1.5M H2SO4 at different
temperatures
Fig. 2: Consequence of CU concentration on the suppression
efficiency of mild steel corrosion in 1.5M
H2SO4 solution at different temperatures
The ulterior parametric quantity gives a step for the
inhibitor public presentation. The kinetic parametric quantities ( B and
R ) and correlativity coefficient ( r2 ) were estimated from
the consecutive lines shown in Fig. 1 and listed in Table 2.
Figure 2 shows the fluctuation of IE % with the
concentrations of CU at different temperatures. Most of
the corrosion suppression is achieved between 1 % and
6 % of CU with merely little betterments at 10 % or
higher. In general, the inhibitor efficiency was observed
to be increased with increasing both CU concentration
and solution temperature.
The surface assimilation of inhibitor species, Inh, on a metal
surface in aqueous solution should be considered as a
topographic point money changer reaction:
Inh + nH O U Inh + nHO ( 4 )
aq 2ads ads 2aq
where, n is the figure of H2O molecules displaced by
one molecule of inhibitor.
When the equilibrium of the procedure described in
Eq. 4 is reached, it is possible to plot the grade of
surface coverage ( q ) as a map of inhibitor
concentration at changeless temperature by different
mathematical looks which are called surface assimilation
isotherms theoretical accounts. Several surface assimilation isotherms were
tested and was found the best description of the
surface assimilation behaviour of the studied inhibitor is by the
Langmuir surface assimilation isotherm Eq. 5:
Cinh. 1
=+ Cinh. ( 5 )
q Kads.
where, Kads is the equilibrium invariable of surface assimilation
procedure. The secret plan of Cinh versus Cinh for CU at different
Q
temperatures gives a consecutive line as shown in Fig. 3. It is
found that all the additive correlativity coefficients ( r2 ) are
about equal to 1.00 and all the inclines are really
near to integrity. From the intercepts of the consecutive lines, Kads
values at different temperatures were obtained.
It is good known that the free energy DGads of
surface assimilation is related to Kads by Eq. 6 ( Noor and Al-
Moubaraki, 2008 ) :
DGads.
log K =- logC – ( 6 )
ads. HO
2 2.303RT
where, CH O is the concentration of H2O molecules
2
and must hold the same unit as that used for inhibitor.
The standard free energies of CU surface assimilation ( DGo ) at
ads
different temperatures were calculated. A secret plan of DGads
versus T in Fig. 4 gave the heat of surface assimilation ( DHads )
and the information of surface assimilation ( DSads ) harmonizing to the
thermodynamic basic Eq. 7 ( Babakhouya et al. , 2010 ) :
DG =D H – TDS ( 7 )
ads ads ads
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Table 3:
Adsorption parametric quantities ( ( Kads, DGads, DHads and ( DSads ) for
CU on mild steel surface in 1.5M H2SO4 solution at
different temperatures
T ( C ) Kads DGads DHads DSads
… ..
( mL1L ) ( kJ mol1 ) ( kJ mol1 ) ( J K1mol1 )
30o 0.0404 -9.330
40o 0.1702 -13.40
50o 0.1941 -14.18 60.01 231
60o 0.4735 -17.10
70o 0.7738 -19.03
Fig. 3: Langmuir isotherm for surface assimilation of CU on
mild steel surface in 1.5M H2SO4 at different
temperatures
Fig. 4: The fluctuation of DGads with T
Table 4: Activation parametric quantities ( E # , DH # and DS # ) for mild steel
app
corrosion in 1.5M H2SO4 solution in absence and presence
of different concentrations of CU
isoniazid. C #
app E DH # DS #
milliliter % ( kJ mol-1 ) ( kJ mol-1 ) ( J K-1mol-1 )
0 79.17 76.49 -90.82
1 41.92 39.24 -217.44
2 27.97 25.29 -264.04
6 28.87 26.19 -267.45
10 30.73 28.06 -264.51
14 18.01 15.33 -308.12
The thermodynamic informations obtained for CU
utilizing the surface assimilation isotherm are collected in
Table 3.
The thermodynamic activation parametric quantities were
calculated from Arrhenius-type secret plan ( Eq. 8 ) and
passage province equation ( Eq. 9 ) ( Faiku et al. ,
2010 ) :
E #
log r= log A – app. ( 8 )
2.303RT
R R DS # DH #
log ( ) = [ ( log ( ) ) + ( ) ] .
( 9 )
T hN 2.303R 2.303RT
where,
E # , DH # and DS # are the evident activation
app
energy, the heat content of activation and the information of
activation. A is the frequence factor which has the same
unit as that of the corrosion rate.
Figure 5 shows the typical secret plans of logr versus 1
Thymine
R 1
while Fig. 6 shows the secret plans of log versus ; straight
Terrestrial time
lines with good correlativity coefficients were obtained.
All thermodynamic activation parametric quantities were
estimated and listed in Table 4.
Figure 7 gives the dependance of both E # and DH #
app
of mild steel corrosion in 1.5 M H2SO4 on the
concentration of CU.
Figure 8 illustrates thhe optical micrographs for
mild steel surface before and after submergence for
90 min in 1.5 M H2SO4 at 30 and 70 C. While
Fig. 9 and 10 illustrate the structural characteristics of
mild steel surface in 1.5M H2SO4 in absence and
presence of 1 and 10 % of CU at 30 and 70 C,
severally.
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Am. J. Applied Sci. , 8 ( 12 ) : 1353-1362, 2011
Fig. 5: Arrhenius secret plans for mild steel corrosion rates in
1.5M H2SO4 in absence and presence of
different concentration of CU
Fig. 6: Passage province secret plans for mild steel corrosion
rates in 1.5M H2SO4 in absence and presence of
different concentration of CU
Fig. 7: Dependence of both evident activation energy
and enthalpy alteration of mild steel corrosion in
1.5 thousand H2SO4 on the concentration of CU
Fig. 8: Micrographs for mild steel surface before ( A )
and after submergence for 90 min in 1.5M H2SO4
at 30 C ( B ) and 70 C ( C )
Discussion
Consequence of CU concentration on mild steel corrosion at
different temperatures: The collected informations in Table 1
can be summarized as follows:
At changeless temperature, mild steel corrosion rate
tends to diminish dramatically with increasing CU
concentration. This consequence indicates the good
inhibitive belongingss of the studied inhibitor
At changeless concentration, mild steel corrosion rate
additions with increasing solution temperature
obeying Arrhenius relationship
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Fig. 9:
Micrographs for mild steel surface in 1.5M
H2SO4 in absence ( A ) and presence of 1 % ( B )
and 10 % ( C ) of CU at 30 C
The present consequences are in good understanding with
those obtained antecedently by ( Noor, 2004 ) when CU
had been studied as corrosion inhibitor for mild steel in
HCl solution at different temperatures. On the other
manus, The informations in Table 2 was interpreted as below:
As was observed the reaction invariables ( B ) have
negative mark, bespeaking that the mild steel
corrosion rate is reciprocally relative to the
concentration of CU. However, the absolute value
of changeless B additions with increasing temperature
up to 50 C and so no alteration in B value was
observed with farther addition in temperature. This
consequence indicates that CU becomes more effectual as
corrosion inhibitor with increasing temperature and
at comparatively high temperatures no appreciable
alteration in the suppression efficiency was observed
Fig. 10: Micrographs for mild steel surface in 1.5M
H2SO4 in absence ( A ) and presence of 1 % ( B )
and 10 % ( C ) of CU at 70 C
The obtained correlativity coefficients
( 0.94 r2 0.99 ) indicate that the corrosion rates of
mild steel in the presence of different
concentrations of CU fit good Eq. 3. Extra
grounds of the quality of tantrum is presented in Fig.
11 in which predicted values of R are plotted
against the corresponding experimental values of
different concentrations of CU. Reasonable
understandings between experimental and predicted
consequences are obtained
The inhibitor action could be explained by
Fe ( Inh ) ads reaction intermediate as follows Eq. 10
( Dubey and Singh, 2007 ) :
Ns +
Fe
+ Inh U Fe ( Inh ) ads U Fe + Inh + n vitamin E ( 10 )
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Fig. 11: Experimental values against predicted values of
mild steel corrosion rate in 1M H2SO4 solution
incorporating different concentrations of CU at
different temperatures
The adsorbed bed combats the action of sulfuric
acerb solution and enhances protection of the metal
surface ( Quraishi et al. , 2000 ) . When there is
deficient Fe ( Inh ) ads to cover the metal surface ( if the
inhibitor concentration was low or the surface assimilation rate
was slow ) , metal disintegration would take topographic point at sites
on the mild steel surface which are free of Fe ( Inh ) ads.
With high inhibitor concentration a compact and
coherent inhibitor bed signifiers on mild steel surface,
cut downing the onslaught on the metal surface. Hence, the
suppression efficiency is so straight relative to the
fraction of the surface covered with adsorbed inhibitor.
Figure 2 implies that most of the corrosion
suppression is achieved between 1 % and 6 % of CU with
merely little betterments at 10 % or higher. In general,
the inhibitor efficiency was observed to be increasing
with increasing both CU concentration and solution
temperature. These consequences can be discussed as follows:
The addition in IE % with increasing CU
concentration is attributed to the interaction
between the inhibitor species and mild steel surface
taking to adsorb the former on the latter. The
adsorbed measure additions with inhibitor
concentration and consequently more active
corrosion centres were reduced ( Shetty et al. , 2006 ;
Achary et al. , 2008 ) . On the other manus, the limited
alteration in IE % at comparatively higher concentrations
of CU may be related to come up impregnation with
inhibitor species ( Noor, 2009 )
The addition in IE % with increasing temperature
was interpreted in the literature by different ways.
Amar and El Khorafi ( 1973 ) , related this to specific
interactions between the metal surface and the
inhibitor molecules. Considered that with addition
in temperature some chemical alterations occur in the
inhibitor molecules taking to an addition in the
negatron densenesss at the surface assimilation centres of the
molecule doing betterment in inhibitor
efficiency eventually. Considered that the addition of
IE % with increasing temperature is a consequence of
alteration in the nature of surface assimilation manner ; the
inhibitor species are being physically adsorbed at
lower temperatures while chemosorption is
favoured as temperature additions
To turn out the chemosorption procedure for CU species
on mild steel surface, some thermodynamic
considerations for both inhibitor surface assimilation and
corrosion activation must be evaluated.
Thermodynamic-adsorption considerations:
Obviously, Fig. 4 shows the dependance of DGads on T,
bespeaking a good correlativity among the
thermodynamic parametric quantities. The negative values of
DGads ( Table 3 ) stress the spontaneousness of the
surface assimilation procedure and the stableness of the adsorbed
bed on the steel surface. As was observed the values
of DGads go more negative with increasing
temperature, bespeaking that the surface assimilation power of
CU increases with the addition of temperature. On the
other manus, the high positive value of DHads ( Table 3 )
ensures that CU species adsorbed chemically on mild
steel surface, while the accompanied big, positive
value of DSads ( Table 3 ) indicates that an addition in
perturbing takes topographic point in traveling from reactants to the
metal-adsorbed species reaction composite. Similar
consequences were reported in recent plants ( Bentiss et al. ,
2005 ; Noor, 2007 ) .
Thermodynamic-activation considerations: The
obtained informations in Table 4 can be interpreted as below.
#
The values of both Eapp and DH # in absence and
presence of different concentrations of CU are
positive, bespeaking that the corrosion procedure is
endothermal
#
The lower values of Eapp in the inhibited solutions
as compared to that of the uninhibited solution
suggest chemosorption mechanism for the CU
species on mild steel in the studied medium
( Popova et al. , 2003 ) . This consequence is in good
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Am. J. Applied Sci. , 8 ( 12 ) : 1353-1362, 2011
understanding with the obtained thermodynamic informations
of surface assimilation ( Table 3 )
#
The lessening in Eapp with CU concentration ( Fig. 7 )
supports the thought of chemosorption mechanism. This
was attributed by ( Hoar and Holliday, 1953 ) to a
slow rate of inhibitor surface assimilation with a end point
closer attack to equilibrium during the
experiments at the higher temperature. Furthermore,
( Riggs and Hurd, 1967 ) explained that the lessening
in activation energy of corrosion at higher degrees of
suppression arises from a displacement of the net corrosion
reaction from that on the exposed portion on the
metal surface to the covered 1
#
Eapp -Cinh relation ( Fig. 7 ) shows a tableland in the
concentration scope from 2-10 % which may be
attributed to that with increasing inhibitor
concentration, the covered country with inhibitor
species additions and the metal surface becomes
near to be saturated, taking to limited alteration in
the evident activation energy. While at 14 % of
CU concentration a bead in E # value was
app
observed which indicates that the metal surface
may be wholly blocked with chemically
adsorbed inhibitor species taking to foster
#
lessening in the Eapp
As expected DH # values have the same tendency as
#
that for Eapp, detecting that the latter is larger than
the former. Noor ( 2007 ) attributed this consequence to
the gaseous reaction ( hydrogen development )
associated with the corrosion procedure which may
lead to a lessening in the entire volume of the
corrosion system. So, harmonizing to the footing of
thermodynamics the inequality E # & A ; gt ; DH # is true.
app
Large and negative values of DS # imply that the
activated composite in the rate finding measure
represents an association instead than a dissociation
measure, intending that a lessening in perturbing takes
topographic point on traveling from reactants to the activated
composite ( March, 1992 ) . However, the value of DS #
lessenings with increasing CU concentrations
Surface morphological surveies: Inspection Fig. 8
through A to C indicates that the sum of corrosion
merchandises every bit good as the size of cavities on mild steel surface
are relative to the solution temperature, intending
that mild steel surface attacked severley by raising the
temperature from 30-70 C. Figure 9 and 10 show
interesting behavior with the add-on of 1 % and 10 %
CU at low and high temperatures. This is that mild
steel surface in the presence of CU is modified and
becomes smooth non merely by increasing CU
concentration but besides by increasing solution
temperature, stressing the chemosorption
mechanism suggested antecedently.
Inhibitor components and surface assimilation mechanism:
Table 5 illustrates the chief components of CU as given,
while Fig. 12 represents the molecular construction of the
chief organic components of CU and their IUPAC
names. Inspection of CU components, reveals that the
organic constituents can be classified as nitrogen-bearing
organic compounds. N-containing organic compounds
were reported in the literature as effectual corrosion
inhibitors for mild steel in acerb solutions ( Shetty et al. ,
2006 ; Popova et al. , 2003 ; Muralidharan et al. , 1995 ;
Ebenso et al. , 1999 ; Noor, 2005 ) .
Chemisorption procedure involves charge sharing or
charge transportation from the inhibitor molecules to the
metal surface. This is possible in instance of positive as
good as negative charges on this surface. The presence
of inhibitor molecules holding comparatively slackly bound
negatrons or hetero atoms ( N in the present work )
with lone-pair negatrons, with a passage metal holding
vacant, low-energy orbital facilitates the
chemosorptions mechanism ( Bentiss et al. , 2005 ) .
Figure 13 shows the suggested chemosorption
mechanism between the vacant d-orbital of Fe atoms
in mild steel surface and the N atoms of CU
organic components. It is impossible to state which
one of these organic components is responsible for
CU inhibitive action. So CU can be treated as a
bundle of inhibitors which may move synergistically.
Table 5: The mean concentration degree of the chief components of
Camel s urine
The constitutional Urea Uric acid Creatinine Chloride Phosphate Sulphate
The concentration 0.195 6.041 0.052 0.45 0.171 7.76
( g L-1 )
Fig. 12: The molecular construction and the IUPAC name
of the chief organic components of CU
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Fig. 13: The suggested chemosorption mechanism
between the vacant d-orbital of Fe atoms in
mild steel surface and the N atoms of the
organic components of CU
Decision
CU acts as a good inhibitor for the corrosion of
mild steel in 1.5 M H2SO4. The suppression
efficiency values increase with the inhibitor
concentration and the solution temperature
The surface assimilation of CU on the mild steel surface
obeys the Modified Langmuir surface assimilation isotherm
suggestion monolayer surface assimilation of CU species
O
The negative values of ( DGads ) emphasize the
spontaneousness of the surface assimilation procedure and the
stableness of the adsorbed bed on the steel surface.
O
DGads values become more negative with
increasing temperature, bespeaking that the
surface assimilation power of CU additions with the addition
of temperature
O
The estimated high, positive value of DHads ensures
that CU species is adsorbed chemically on mild
steel surface
All values of E*
app. for mild steel corrosion in
inhibited solutions were lower than that for the
uninhibited solution bespeaking the happening of
chemosorption mechanism for the CU species on
mild steel in the studied medium
The surface morphology of mild steel in absence
and presence of inhibitor revealed that with
increasing both CU concentration and solution
temperature, mild steel surface is modified and
expressions smooth
Good correlativity between the inhibitor components
and its repressive action was obtained
