1) The document describes the synthesis and characterization of four cationic surfactants based on N-hexamethylenetetramine and alkyl chlorides. 2) The surfactants were tested for their antimicrobial activity against four bacterial strains. The maximum activity was observed for N-hexamethylenetetramine-N-ethyl silane ammonium trichloride (Ah) which showed 73% inhibition of Staphylococcus aureus. 3) Surface tension measurements were performed to determine properties like critical micelle concentration and thermodynamic parameters of adsorption and micellization. Fourier transform infrared spectroscopy and mass spectrometry were used to characterize the synthesized surfactants.

1. 1 23
Journal of Surfactants and
Detergents
ISSN 1097-3958
Volume 18
Number 3
J Surfact Deterg (2015) 18:529-535
DOI 10.1007/s11743-014-1662-6
Synthesis and Characterization of
Cationic Surfactants Based on N-
Hexamethylenetetramine as Active
Microfouling Agents
Rafat M. Mohareb, Abdelfatah
M. Badawi, Mahmoud R. Noor El-
Din, Nesreen A. Fatthalah & Marian
R. Mahrous

2. 1 23
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3. ORIGINAL ARTICLE
Synthesis and Characterization of Cationic Surfactants Based
on N-Hexamethylenetetramine as Active Microfouling Agents
Rafat M. Mohareb • Abdelfatah M. Badawi •
Mahmoud R. Noor El-Din • Nesreen A. Fatthalah •
Marian R. Mahrous
Received: 16 January 2014 / Accepted: 10 December 2014 / Published online: 3 January 2015
Ó AOCS 2014
Abstract Four cationic surfactants of quaternary hex-
ammonium silane chloride based on hexamethylenetetra-
mine and alkyl chloride were synthesized. The chemical
structures of the prepared cationic surfactants were eluci-
dated using Fourier transform infrared (FT-IR) spectros-
copy and mass spectrometry analysis. The surface and
thermodynamic properties of the prepared surfactants were
also studied. The performance of these cationic surfactants
as microfouling agents against two strains of Gram-nega-
tive bacteria, namely, Pseudomonas aeruginosa and
Escherichia coli, and two strains of Gram-positive bacteria,
namely, Staphylococcus aureus and Bacillus subtilis, were
evaluated as antimicrobial agents. The results showed that
the maximum antimicrobial activity was detected for N-
hexamethylenetetramine-N-ethyl silane ammonium tri-
chloride (Ah). The maximum and minimum antimicrobial
activities were 73 and 60 % against S. aureus and E. coli,
respectively, at a concentration of 5 mg/l, pH 7, and 37 °C.
Keywords Microbial fouling Á Quaternary
hexammonium silane Á Cationic surfactants Á Antimicrobial
activity
Introduction
One of the most important problems facing the marine
industries is biofouling, which affects underwater infra-
structure components such as electrical cables, petroleum
pipelines, fishing nets, etc. [1]. Microbes, bacteria, micro-
algae, and higher microorganisms, e.g., aquatic fungi, infu-
soria, rotifers, etc., live and multiply on the surfaces of
pipelines immersed in water, refrigerators, and heat
exchangers, inside flameless heating equipment in the pre-
sence of aqueous media, and in systems for biochemical
treatment of wastewaters. Heat and mass exchange worsen
sharply, thermal power consumption increases, output and
passability decrease, accidents occur in manufacturing units,
and corrosion of metal surfaces intensifies as a result of
biological fouling of this equipment [2]. Marine microor-
ganisms like Escherichia sp., Staphylococcus sp., and
Pseudomonas sp. are known to be effective in the biofouling
process [3]. Moreover, Pseudomonas sp., the most prevalent
in the water and seawater industries, have been implicated in
the corrosion process of stainless and mild steels, and alu-
minum alloys in marine habitats. In industrial settings of
cooling-water towers, water pipelines, membrane unit, and
food-processing plants, the unwanted biofilms of Staphylo-
coccus aureus and Staphylococcus epidermidis are respon-
sible for fouling [4]. The most widely practiced approach to
the minimization of biofilms in industrial water systems is by
way of chemical treatment focusing either on the reduction
of microbial numbers using biocides, or their removal using
either synthetic dispersants or enzymes [5]. Different types
Electronic supplementary material The online version of this
article (doi:10.1007/s11743-014-1662-6) contains supplementary
material, which is available to authorized users.
R. M. Mohareb
Department of Chemistry, Faculty of Science, Cairo University,
Giza, Egypt
A. M. Badawi Á M. R. Noor El-Din (&) Á N. A. Fatthalah
Egyptian Petroleum Research Institute, 1 Ahmed El- Zomor St.,
Nasr 11727, Cairo, Egypt
e-mail: mrned04@yahoo.com
M. R. Mahrous
Science and Technology Center of Excellence, Cairo, Egypt
123
J Surfact Deterg (2015) 18:529–535
DOI 10.1007/s11743-014-1662-6
Author's personal copy

4. of surfactants can act as antimicrobial agents by interaction
with a microorganism’s cellular membranes [6, 7]. However,
the surfactants are easily adsorbed at liquid–solid interfaces
and can protect different surfaces from microorganism
adhesion by forming protective coated surfaces [8].
The first use of cationic surfactants in the field of anti-
bacterial resistance was recorded by Domagk in 1935 [9] and
since that date, hundreds of new cationic surfactants have
been synthesized and used as germicides and/or fungicides
[10]. Alkyl pyridinium, alkyl trimethylammonium halides
and hexamine derivatives, and 1-(3-chloroallyl)-3,5,7-triaza-
1-azoniaadamantane chloride are the most widely com-
pounds used in the field of biofouling resistance [10, 11].
Also, quaternary ammonium compounds (QACs) are com-
monly used as effective biocidal agents, as they have superior
properties compared to known antibacterial agents such as
better membrane penetration, excellent environmental sta-
bility, lower toxicity, higher corrosion inhibition effect, and
lower skin irritation [12–16]. QACs have a broad spectrum of
antimicrobial activity against both Gram-positive and Gram-
negative bacteria [17]. As QACs are positively charged
cations, their mode of action is related to their attraction to
negatively charged materials such as bacterial proteins [18].
The objective of the present work was to synthesize a new
series of cationic silicon-based quaternary hexammonium
surfactants for use as microfouling agents. These surfactants
were prepared by condensing an amine (containing a triva-
lent nitrogen) with alkyl silicon mono-, di-, and trichlorides.
The efficiency of the prepared surfactants as microfouling
agents against three strains of bacteria was investigated. In
addition, the effect of surface and thermodynamic parameters
on the efficiency of the synthesized surfactants was studied.
Experimental
Materials
Analytical grades of hexamethylenetetramine, trichloroeth-
ylsilane, trichlorohexylsilane, dichlorodiethylsilane, and
chlorotriethylsilane were purchased from Sigma–Aldrich
Co., UK. Technical grade dimethylformamide (DMF) was
obtained from Fluka, Germany. Deionized water was uti-
lized in all experiments.
Method
Synthesis of Quaternization
of Hexamethylenetetramine
A 0.1-mol sample of each silane, namely, trichlorohex-
ylsilane, trichloroethylsilane, dichlorodiethylsilane, and
chlorotrimethylsilane, was reacted with hexamethylenetet-
ramine (0.3, 0.3, 0.2, and 0.1 mol, respectively; the number
of moles of hexamethylenetetramine was chosen on the
basis of the number of chlorine groups in the silane). At the
beginning of each reaction, the hexamethylenetetramine
was dissolved in 40 ml of hot DMF and then treated with
the silane in a 500-ml flask fitted with a Dean-Stark trap
equipped with a condenser and continuously stirred at
400 rpm for 8 h. The reaction mixture was cooled and
filtrated. The precipitate was washed with acetone. The
solvent was evaporated using an evaporator. Each of the
prepared surfactant was washed twice with acetone and left
in room temperature for drying until constant weight. The
chemical structure of the synthesized quaternary hexam-
monium chloride surfactants is shown Fig. 1.
Chemical Conformation
The chemical structures of the prepared surfactants were
confirmed using Fourier transform infrared (FT-IR) spec-
troscopy (Thermoscientific, Nicolet iS10 FT-IR, USA) and
mass spectrometry analysis (Alpha Omega Technologies,
Inc., Brielle, NJ).
Evaluation of the Synthesized Surfactants
as Microfouling Agents
The antimicrobial activity of each of the synthesized cat-
ionic surfactant, namely, N-hexamethylenetetramine-N-
ethylsilane ammonium trichloride (Ah), N-hexamethy-
lenetetramine-N-diethylsilane ammonium dichloride (Dh),
N-hexamethylenetetramine-N-triethylsilane ammonium
chloride (Ch), and N-hexamethylenetetramine-N-hexylsi-
lane ammonium trichloride (Bh), was evaluated as a
microfouling agent against four bacterial strains: Pseudo-
monas aeruginosa ATCC 10145, Escherichia coli ATCC
23282 (Gram-negative bacteria), and Staphylococcus aureus
ATCC 29737, Bacillus subtilis NCTC 10400 (Gram-positive
bacteria) using both the agar well diffusion method and
minimum inhibitory concentration (MIC) test [19, 20].
Agar Well Diffusion Method
The agar well diffusion method depends on the diffusion of
the prepared surfactants through a layer of solidified agar
that inhibits the growth of the microorganism in an area or
zone around the hole containing the antibiotic solution. In
this assay, the size of the inhibition zone and the dose of
the surfactants assayed are correlated. In this study, the
antimicrobial susceptibility was tested on solid (agar–agar)
media. The medium was inoculated with the tested
microorganisms separately and poured into sterilized Petri
dishes (20 ml/dish). The agar medium was punched using a
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5. sterile cork borer to make five holes of 10 mm. For each
surfactant, a stock solution was prepared at a concentration
of 5 mg/ml. About 100 ll of each stock solution was added
using a sterile micropipette into four holes and allowed to
diffuse at 4 °C for 2 h and then incubated at 37 °C for
24 h. The fifth hole was filled with control solution (which
has no surfactant). The negative control was DMF that
showed no antimicrobial activity against the tested
microorganisms. The diameter of the inhibition zone
(millimeters) was measured. The previously step was
repeated twice for each surfactant and the average values
were recorded [20].
Minimum Inhibitory Concentration (MIC) Test
In microbiology, MIC is defined as the lowest concentra-
tion of an antimicrobial that inhibits the visible growth of a
microorganism after overnight incubation [21]. Serial
dilutions of the four tested compounds were prepared in
macrodilution tubes at a range of concentrations (dilution
N
N
N
N
RSiCl(x)
Hexamethylenetetramine
(C6H12N4)
where R=2 or 3 molecules of ethyl group
R
=1 molecule of ethyl or hexyl group
x=1, 2 or 3
Si Cl
Si
N4C6H12
C2H5
Cl
Si
R
C2H5
C2H5C2H5
C2H5
or
R
SiCl(x)
N-hexamethylene tetramine -N-
diethyl silane ammonium dichloride
(Dh)
N-hexamethylene tetramine-N-
triethyl silane ammonium chloride
(Ch)
N-hexamethylene tetramine -N-alkylsilane ammonium trichloride
(Ah and/or Bh)
Alkyl silicon chloride
+2
-2
+1
-1
N4C6H12
N4C6H12
+3
Cl
-3
N4C6H12
N4C6H12
H12C6N4
Fig. 1 Chemical structure of
the synthesized quaternary
hexammonium chloride
surfactants
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6. factor ranging from 1/2 to 1/64). Bacterial suspensions
were adjusted to the logarithmic growth phase to match the
turbidity of a 0.5 McFarland standard, yielding approxi-
mately 108
CFU/ml. The same amounts of bacteria were
added to all tubes and the tubes were incubated at 37 °C for
24 h. Each tube was examined for growth and compared to
the control. Bacterial suspension added to a tube filled with
nutrient broth without each of the tested compounds was
used as a positive growth control. A tube not containing
nutrient broth was used as a negative growth control. The
absence of growth was defined as antibacterial activity.
Surface Tension Measurements (c)
The surface tension (c) of the prepared cationic surfactants
at 25 °C was measured using a Du Nou¨y tensiometer
(Kruss-K6 type) by applying the platinum ring technique.
The surface tension of each surfactant was measured three
times within a 3-min interval between each reading [22].
The critical micelle concentration (cmc) was determined
from the abrupt change in the slope of surface tension
(ccmc) versus logarithm of the concentration curve (ln C).
From the slope of a plot of c versus ln C, the maximum
surface excess concentration (Cmax) and the minimum
surface area per surfactant (Amin) were calculated. Also, the
thermodynamics parameters of adsorption and micelliza-
tion Gibbs free energies, such as Gibbs free energy of
adsorption (DGads) and the Gibbs free energy of micelli-
zation (DGmic), for the prepared surfactants were calculated
by utilization of Gibb’s adsorption equations [23].
Results and Discussion
Characterization of Quaternary Hexammonium Silane
Compounds
The prepared surfactants (Ah, Bh, Dh, and Ch) were
characterized using both FT-IR spectroscopy and mass
spectrometry analysis and the biological activities are
discussed in the following section.
FT-IR Spectroscopic and Mass Spectrum Analyses
The structures of the prepared quaternary hexammonium
silane chloride compounds (Ch and Ah) were elucidated by
FT-IR. The FT-IR spectrum in Fig. S2 is dominated by a
Si–N peak around 900 cm-1
, a Si–C peak at 1,010 cm-1
,
and a C–N peak around 2,350 cm-1
. Figure S3 shows that
the peak intensity at 900 cm-1
is larger in compounds with
higher Si–N content and increases as the extent of hexa-
methylenetetramine increases. This band indicates that
more than one molecule of N-hexamethylenetetramine was
introduced. Also, the decrease of the peak intensity at
1,010 cm-1
indicates that the prepared compound contains
more than one ethyl group. The chemical structures of the
quaternary hexammonium silane compounds were also
confirmed by mass spectrometry (Fig. S2–S4; Table S1 in
supplementary information).
Biological Activity of the Synthesized Surfactants
The synthesized compounds (Ah, Dh, Ch, and Bh) were
evaluated for their microfouling action against P. aerugin-
osa and E. coli as Gram-negative and S. aureus and B.
subtilis as Gram-positive bacteria (Fig. 2). Commonly,
Gram-negative bacteria are resistant towards antibacterial
substances owing to the presence of lipopolysaccharide
molecules in their outer membrane, acting as a barrier to the
penetration of numerous antibiotic molecules which are
related to the enzymes in the periplasmic space that are able
to break down the molecules introduced from outside [24–
26]. By inspection of the data in Fig. 2, the efficiency of the
prepared cationic surfactants is in the order Bh [ Ch =
Dh [ Ah for E. coli, and Ah = Bh [ Ch = Dh for
P. aeruginosa. Also, the maximum inhibition zone was
afforded by Bh surfactant for both organisms. This may be
attributed to the effect of the number of alkyl groups for Ah,
Ch, and Dh and to the length of Bh surfactant on its
adsorption onto the bacterial cell wall. However, the results
show that Ch and Dh have lower inhibition (inhibition
zone = 20 cm) efficiency against P. aeruginosa than that
of Ah (inhibition zone = 24 cm) and this may be attributed
to the number of alkyl groups. Also, the results show that Bh
surfactant have a high inhibition zone (3.5 cm) comparing
with Dh, Ch, and Ah; this may be attributed to the effect of
alkyl group length. Regarding Gram-positive bacteria, the
highest antimicrobial activity against S. aureus was affor-
ded by Ah surfactant (Fig. 2). As a result of the structure of
the cell wall of Gram-positive bacteria, which consists of
0
5
10
15
20
25
30
35
40
45
50
+ve control Ah Bh Ch Dh
Surfactant
Inhibitionzone(mm)
Pseudomonas aeruginosa
Escherichia coli
Staphylococcus aureus
Bacillus subtilis
Fig. 2 Antimicrobial activity of the tested surfactants against
microbiofouling Gram-negative and Gram-positive bacteria (using
three repeated readings and Excel software)
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7. several layers of peptidoglycan and molecules of tei-
choic acid that are perpendicular to the peptidoglycan
sheets, it is probable that the positive charge of the qua-
ternary hexammonium compounds causes the simple
adsorption to the cell wall surface via electrostatic inter-
action between the N?
group of the surfactant and the
COO-
of teichoic acid. Accordingly, carboxypeptidase
enzyme was blocked and caused destruction by increasing
the permeability or ‘‘leakiness’’ of the lipid cell membrane.
The blocking of carboxypeptidase enzymes also blocks cell
wall synthesis [27]. The number of alkyl groups is another
important factor affecting the surfactant performance. As a
result, the antimicrobial activities of the prepared surfac-
tants decreased as the number of alkyl groups increased as
follows: Ah [ Dh [ Ch [ Bh. This may be attributed to
the increase in the molecules’ lipophilicity as a result of the
presence of more hydrophobic chains; this increases the
time for attacking of the cell wall by N?
(hindrance effect)
and crossing it to the cell membrane (see Scheme 1 in
supplementary information) [26]. From the data illustrated
in Fig. 2, it is clear that the Gram-negative bacteria are
more resistant to the prepared surfactants than Gram-posi-
tive bacteria. The results show that P. aeruginosa exhibited
the minimum antibacterial activity compared to other
Gram-positive bacteria strains. This may be attributed to the
effect of bacterial cell wall structure (double membrane
structure). As a result of the presence of the outer mem-
brane, the adsorption of QACs on the cytoplasm membranes
will be decreased [12].
MIC Values
It is well known that the lower MIC values of the tested
surfactants give the higher antimicrobial activity [28]. The
MICs of Ah for P. aeruginosa and E. coli (Gram negative)
and S. aureus and B. subtilis (Gram positive) strains are
shown in Table S2 (in supplementary information). Results
show that the MIC value of Bh is the most effective
compound against both E. coli (0.75 mg/l) and P. aeru-
ginosa (0.75 mg/l) comparing with the other tested sur-
factants. On the other hand, it is noticed that Ah have the
lowest MIC value of 0.37 and 0.75 mg/l for S. aureus and
B. subtilis, respectively. The obtained results from the
measurements of biological activity are in a good agree-
ment and consistent with these obtained by MICs values
for all tested surfactants.
Surface Active and Thermodynamic Properties
of the Prepared Cationic Surfactants
The surface properties of the prepared surfactants including
the cmc, the values of surface tension at the cmc (ccmc), the
maximum surface pressure (pcmc), the maximum surface
excess concentration at surface saturation ‘‘effectiveness’’
(Ccmc), and the minimum surface area per surfactant mole-
cule (Acmc) are listed in Table 1 and illustrated in Fig. 3.
From the obtained results, it is obvious that the surface ten-
sion (ccmc) was decreased of 37, 39, and 41 mNm-1
for Ah,
Dh, and Ch, respectively by increasing the ethyl group. This
refers to increasing the hydrophobicity of molecules [29].
Regarding the surface parameters and antimicrobial activity
listed in Table 1 and Fig. 2, it was found that compound Ah
possessed the lowest surface tension (ccmc) of 37 mNm-1
as
well as the highest antimicrobial activity towards S. aureus
bacteria compared with Dh and Ch surfactants. This could be
explained because Ah surfactant contains three quaternary
hexammonium groups reflecting its high lipophilicity that
facilitates its penetration into the Gram-positive bacteria cell
wall by adsorption of N?
onto the negatively charged
receptors of the bacterial cell wall. Also, from Table 1 and
Fig. 2, it was found that the lowest surface tension (ccmc) of
35 mN m-1
and the minimum antimicrobial activity were
obtained with Bh in comparison with Ch, Dh, and Ah sur-
factants against S. aureus. Increasing the length of the
hydrophobic group in Bh leads to a decrease in the solubility
of the surfactant in water. Meanwhile, the surfactants mol-
ecules at the interface become more close each to other (on
parole the area occupied by hydrophilic group at the interface
allow it), which in turn leads to disruption of the absorption
of the surfactant on the surface [30]. Accordingly, an
increase in the alkyl chain length (hexyl group) followed by
an increase in the hydrophobic interaction, which in turn
‘‘sucks’’ the molecule further into the membrane, is followed
by growing destabilization of membrane fluid and hence
decreases the concentration that destroys the cell. Concern-
ing the more resistant Gram-negative bacteria which have
very thick cell membranes, compound Bh showed the
highest antibacterial activity. Compound (Bh) has the lowest
cmc, 0.977 9 10-3
mol dm-3
, indicating its highest surface
activity that might facilitate its penetration through the
bacterial cell membrane, which results in increasing the
repulsion between the polar atom (N?
) of Bh and the non-
polar cell wall of the tested bacteria so that the molecules
tend to aggregate via the alkyl chain (Bh has the bulkiest
alkyl chain) on the cell wall surface at low concentration
[31]. Accordingly, the high resistance of Gram-negative
bacteria might reflect their abilities to minimize the antimi-
crobial activities of the tested compounds. Generally, the
accumulation of the surfactants at the interface was descri-
bed by minimum surface excess (Cmax) values. The data in
Table 1 shows that a decrease of the hydrophilic moiety of
the surfactant molecules decreases the Cmax. Therefore, the
surface excess concentration of the prepared cationic sur-
factants was decreased by decreasing the hydrophilic group.
This means that the possibility of the surfactant becoming
more soluble in water would be decreased. As a result of the
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8. decreasing of the Cmax values, the area at the interface for
each surfactant molecule will be increased [30]. The mini-
mum surface area occupied by each surfactant molecule at
the air–water interface (Amin) was calculated and was
affected by the presence of the polar and/or charged groups
[30]. Also (for cationic surfactants), the competition between
van der Waals forces among aliphatic chains and repulsive
interactions (electrostatic or hydration) between polar head
groups impacts on the resulting value of Amin [32]. That is the
reason for the lower Amin value of Bh compared to those of
Ah, Dh, and Ch. The standard free energies of micellization
(DGmic) and adsorption (DGad) of the synthesized surfactants
were calculated and the results are listed in Table 1. From the
obtained data of DGmic, it can be concluded that the micel-
lization process is spontaneous because DGmic 0. Gener-
ally, DGad is lower than DGmic values. This indicates that
these surfactants favor adsorption more than micellization.
Obviously, this favorability of adsorption is attributed to
interaction forces between hydrophobic chains and the polar
medium and that are minimum value the surfactant
molecules are situated at the air/water interface. Thus,
the maximum -DGad (-20.33 kJ/mol) was obtained by
(Ah) that exhibited the maximum inhibition efficiency for
Gram-positive bacteria.
Conclusion
Four cationic surfactants (Ah, Dh, Ch, and Bh) were syn-
thesized and their antimicrobial activity against two strains
of Gram-negative and two strains of Gram-positive bacte-
ria were studied. The antimicrobial activity was found to
increase with increasing the hydrophilic group of the pre-
pared surfactants Ah, Dh, and Ch towards Gram-positive,
whereas the most effective parameter affecting the activity
of the surfactant Bh against Gram-negative bacteria is the
chain length of the cationic surfactant. The results also
show that the surface tension of the surfactants has a sig-
nificant effect on the antimicrobial activity for Gram-neg-
ative and Gram-positive bacteria.
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Table 1 Surface active properties and thermodynamic parameters of the synthesized cationic surfactants
Surfactant Cmca
(mol dm-3
910-3
)
ccmc
a
(mN m-1
)
pcmc
b
(mNm-1
)
Cmax
b
(mol/cm-2
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Amin
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(nm2
/molecule)
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(kJ/mol)
DGad
b
(kJ/mol)
Ah 1.01 37 35 1.03 160.68 -16.94 -20.33
Dh 1.43 39 33 1.06 156.40 -16.22 -19.33
Ch 2.15 41 31 1.09 151.79 -15.21 -18.00
Bh 0.977 35 37 1.11 149 -17.17 -20.49
a
Values reflect the precision of the tensiometer
b
Values reflect the precision of the Excel software
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-14-12-10-8-6-4-2
ln c, mol dm-3
γ,mNm-1
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Ch
Bh
Fig. 3 c–ln C adsorption isotherm for prepared cationic surfactants
(using three repeated readings and Excel software)
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Rafat M. Mohareb is a professor of pharmaceutical organic
chemistry. He was awarded a Fulbright fellowship, USA in 1999,
and an Alexander von Humboldt fellowship, Germany, in 1987–1989.
His research interests include the synthesis and SAR of newly
synthesized heterocyclic compounds.
Abdelfatah M. Badawi is a professor of applied organic chemistry at
the Egyptian Petroleum Research Institute (Applied Surfactant
Laboratory) and is General Secretary for the International Society
of Therapeutic, Experimental and Clinical Research (Bastia, France).
He received his undergraduate training in chemistry at Cairo
University, Ph.D. in applied chemistry from Azhar University, and
D.Sc. degree in applied organic chemistry at Toronto University. He
has been a visiting professor at Arkansas University for Medical
Sciences (USA). He has participated in the research of applied
surfactant, metallosurfactant chemistry, and nanotechnology. His
research interests are in the areas of both environmental chemistry
and medicinal chemistry with special emphasis on antitumor agents.
His current research involves investigations on metal-based drugs.
Additional interests include the development of biocides and inves-
tigation of nanotechnology for destruction of both environmental
pollutants and tumors.
Mahmoud R. Noor El-Din received his Ph.D. from the Faculty of
Science, Ain Shams University, Cairo, Egypt. He is currently an
associate professor of applied organic chemistry at the Petroleum
Applications Department, Egyptian Petroleum Research Institute
(EPRI), Cairo, Egypt, with research interests in the synthesis of new
surfactants and their applications in petroleum industries. He is
working on the formulation of mini, micro, and nanoemulsions for
different applications. He has 10 years of experience as a researcher
in the Chemical Services and Development Centre (CSDC), EPRI,
Cairo, Egypt.
Nesreen A. Fatthalah received her Ph.D. from the Women’s College
for Science, Ain Shams University, Cairo, Egypt. She is currently a
researcher of marine environmental biotechnology, at the Petroleum
Biotechnology Lab, Processes Development Department, Egyptian
Petroleum Research Institute (EPRI), Cairo, Egypt, with research
interests in biofouling and biocorrosion and their control and
mitigation including biological, chemical, and paints and coatings
with green technology and their applications in petroleum industries.
She is working on biofouling control in heat exchangers using bio-
based nanocoating. She attended different workshops on plasma
applications in the coatings industry. She has 13 years of experience
as a biologist in the Petrochemicals Department, EPRI, Cairo, Egypt
and 5 years as an assistant researcher and 4 years as a researcher in
the Petroleum Biotechnology Lab, Processes Development Depart-
ment, EPRI, Cairo, Egypt.
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