الفهرس 
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Abstract
This work contains three chapters:-Chapter 1: IntroductionAn introduction about surfactants (definition, classification and
applications), an introduction about corrosion (definition, forms,corrosion control and coating), and an introduction about nanotechnology and nanoparticles.Chapter 2: Materials and experimental techniquesThe experimental part included complete description of synthesis
of inhibitors as the following:
1- Synthesis of novel cationic surfactants
a- Synthesis of novel N-
(3-morpholinopropyl)dodecan-
1-aminium bromide (I) by alkylation reaction of
one mole 3-morpholinopropane-
1-amine and one mole of
1-bromododecane.
b- Synthesis of novel N-
(2-(2-mercaptoacetoxy)ethyl)-N,Ndimethyldodecan-
1-aminium bromide (II) was carried out in
two steps as follows:
(i) Synthesis of N-
(2-hydroxyehtyl)-N,N-dimethyldodecane-
1-aminium bromide by quaternization reaction of one mole of
2-(dimethylamino)ethanol and one mole of
1-bromododecane.
Summary and Conclusions
(ii) The product from the previous step was esterified with
2-mercaptoacetic acid to produce N-
2-mercaptoacetoxy)-
ethyl)-N,N-dimethyldodecan-
1-aminium bromide (II).
c- Preparation of copper nanoparticles (CuNPs).
CuNPs were prepared by chemical reduction of CuCl
2 solution
in the presence of synthesized cationic surfactants (I or II).
2- The chemical structure of the prepared compounds was
confirmed using FTIR,
1HNMR and Mass spectroscopes.
3- Description of corrosion tests which used to evaluate the
inhibition efficiency of the used inhibitors for carbon steel
pipelines corrosion
in 1.0 M HCl.
4- Applications of the unmodified and modified paints and
performance of these paints as anti corrosion coats for carbon
steel in
3.5 wt% NaCl solution by different techniques.
Chapter 3: Results and discussion
This chapter included the following parts:-
1- Characterization of the synthesized surfactants by FTIR,
1HNMR and Mass spectroscopy.
2- The surface active properties of the prepared surfactants:-
The data showed that linear decrease in surface tension was
observed with an increase in the surfactants concentrations up to
the Ccmc, beyond which no considerable change was noticed. The
values of effectiveness (πcmc), maximum surface excess (Γmax) and
the minimum surface area (Amin) were calculated.
Summary and Conclusions
iii
Specific conductivity (K) measurements of cationic surfactants
were performed in order to evaluate the Ccmc and the degree of
counter ion dissociation, β. The values of standard free energy for
micellization (ΔGo
m) were calculated. The data showed that the
standard free energies of micellization for the synthesized
surfactants are always negative, indicating that the micellization
is a spontaneous process.
3-The prepared compounds were investigated as corrosion
inhibitors using three techniques:-
a) Weight loss measurements
The data revealed that, the inhibition efficiency of the synthesized
cationic surfactants (I and II) increased with increasing their
concentrations and temperature.
b) Potentiodynamic polarization measurements
The data indicated that all prepared cationic surfactants (I and II)
shifted slightly the polarization curves toward both cathodic and
anodic directions and did not show
any definite trend in 1.0 M
HCl and also the values of icorr decreased with increase of
inhibitors concentration. This behavior confirmed that the
synthesized cationic surfactants acted as mixed type inhibitors.
Moreover, βc values increased with increase of inhibitors
concentration.
The inhibition efficiency of all prepared surfactants increased
with inhibitors concentration increment. This fact suggested that
Summary and Conclusions
iv
the inhibitors species may be adsorbed on the steel surface and
cover some active sites of the electrode surface.
c- Electrochemical impedance spectroscopy (EIS)
a- Nyquist plots
For the two prepared surfactants, the data showed that an increase
of charge transfer resistance and decrease of the pseudo capacity
of the double layer with increasing any inhibitor concentrations
indicated that these inhibitors have the ability to inhibit the
corrosion rate of carbon steel by adsorption mechanism
(formation of a barrier surface film which separates the steel
surface from the corrosive medium).
The results obtained from the weight loss measurements were in
good agreements with those obtained from potentiodynamic
polarization method and electrochemical impedance spectroscopy
(EIS) method.
b- Bode plots
The increase of absolute impedance at low frequencies in Bode
plots confirmed the higher protection with increasing the
concentration of the prepared inhibitors (I and II), which is related
to adsorption of the inhibitors on the carbon steel surface.
The depression of phase angle at relaxation frequency occurs with
decreasing of any inhibitor concentrations which indicated the
decrease of capacitive response with the decrease of inhibitor
Summary and Conclusions
v
concentrations. Such a phenomenon could be attributed to higher
corrosion activity at low concentrations of inhibitors.
4- Thermodynamic parameters:-
a- Activation thermodynamic parameters.
The values of activation energy (Ea) for corrosion process were
calculated from Arrhenius equation in the absence and presence
of the prepared surfactants (I and II). The data indicated that, the
activation energy decreased in the presence of the two cationic
surfactants which indicated the occurrence of chemisorption
(sharing or transferring of electrons from inhibitor molecules to
the metal surface to form a coordinate type of bond). The change
in enthalpy and entropy of activation values (ΔH*, ΔS*) were
calculated from the transition state equation.
b- Adsorption thermodynamic parameters
The adsorption of these cationic surfactants on the carbon steel
surface obeyed the Langmuir adsorption isotherm.
Thermodynamic parameters for adsorption process such as free
standard energy (ΔGo
ads), enthalpy (ΔHo
ads) and entropy (ΔSo
ads)
of the prepared surfactants were determined. The negative values
of (ΔGo
ads) indicated that the adsorption of inhibitors on the metal
surface is spontaneous process. The positive value of ΔHo
ads
indicated that the adsorption of investigated inhibitors (I and II)
on the carbon steel surface is endothermic. The positive sign of
(ΔSo
ads) attributed to the increase of disorder due to the adsorption
Summary and Conclusions
vi
of only one surfactant molecule by desorption of more water
molecules.
5- Quantum chemistry calculations
For all prepared inhibitors, ΔN shows inhibition efficiency
resulted from electron donation, and the inhibition efficiency
increases with the increase in electron-donating ability to the
metal surface. The synthesized inhibitors (I and II) were donors of
electrons, and the steel surface was the acceptor, and this favors
chemical adsorption of the inhibitors on the electrode surface.
6- Scanning electron microscopy (SEM) investigation revealed
that, the surface was strongly damaged in absence of corrosion
inhibitors, where the surface in the presence of corrosion
inhibitors was free from pits and smooths indicating the presence
of a good protective film on the steel surface of the metal and also
confirms the high inhibition efficiency of the prepared
surfactants.
7- Characterization of the CuNPs capped by synthesized cationic
surfactants (I and II) was confirmed by FTIR spectroscopy and
TEM. Results confirmed that the synthesized cationic surfactant
form nanoshells on the prepared CuNPs.
8- Performance of paint by using three techniques:-.
a- Potentiodynamic polarization measurements
Addition of capped CuNPs in the paint inhibited the corro sion of
carbon steel in 3.5 % NaCl solution. The inhibition efficiency
Summary and Conclusions
vii
decreased with increasing the amount of capped CuNPs in the
paint. Ecorr for all prepared surfactants slightly shifted towards the
cathodic side. The value of icorr for electrode painted with blank
(unmodified) paint is usually larger than those obtained using
modified paints containing different amounts of capped CuNPs
(0.5, 1, 2, 4 wt%) and increased with increase of the capped
CuNPs concentration in paint.
b- Electrochemical impedance spectroscopy (EIS)
The data showed that, a decrease of charge transfer resistance and
an increase of the capacity of the double layer by increasing of
concentration of capped CuNPs in the paint.
c- Salt spray test
The salt spray tests of the carbon steel coated by unmodified and
modified paint carried out for 500h
at 35 oC showed that, the
spreading of corrosion underneath the modified coating film
decreased by decreasing of the capped CuNPs concentration. This
behavior further supported the results obtained from the
electrochemical measurements.