Effect of Alternation of Chloropropoxy and Propoxy Units and Impact of the Ethylol-Group Number on Properties of Surfactants

Article abstract of DOI:10.1071/CH18213

Surfactants based on myristic acid, epichlorohydrin, and propylene oxide were obtained in two ways. First, the ester of myristic acid and epichlorohydrin was synthesised, and then with propylene oxide. Second, myristic acid was first reacted with propylene oxide, and then with epichlorohydrin. In both cases, the reactions were carried out at 150-160°C using triethylamine as a catalyst. The obtained chloropropoxy-propoxy and propoxy-chloropropoxy esters of myristic acid are non-ionic surfactants. These products were transformed into cationic surfactants by interaction with several ethanolamines. The specific electroconductance and surface activity of the obtained surfactants, characters that vary with the colloidal-chemical parameters of the surfactants, depended on such factors as the sequence of the epichlorohydrin and propylene oxide units inside the polar group of the obtained ionic surfactants, the presence of the methyl group linked to the N-atom, as well as the number of ethylol groups. It was revealed that the synthesised surfactants possess a property of localising thin (thickness <1 mm) petroleum films spread over different types of water.

Full text of DOI:10.1071/CH18213

CSIRO PUBLISHING
Aust. J. Chem.
Full Paper
https://doi.org/10.1071/CH18213
Effect of Alternation of Chloropropoxy and Propoxy
Units and Impact of the Ethylol-Group Number on
Properties of Surfactants
A
A
A C
,
Gulnara A. Ahmadova, Aygul Z. Abilova, Ravan A. Rahimov,
A
A
B
Seadet M. Askerzade, Ziyafaddin H. Asadov, Fedor I. Zubkov, and
A
Saida F. Ahmadbayova
A
Institute of Petrochemical Processes of Azerbaijan National Academy of Sciences,
Hojaly Avenue 30, AZ 1025, Baku, Azerbaijan.
B
Organic Chemistry Department, Faculty of Science, Peoples’ Friendship University of
Russia (RUDN University), 6 Miklukho-Maklaya Street, Moscow, 117198, Russian
Federation.
C
Corresponding author. Email: revan_chem@mail.ru
Surfactants based on myristic acid, epichlorohydrin, and propylene oxide were obtained in two ways. First, the ester of
myristic acid and epichlorohydrin was synthesised, and then with propylene oxide. Second, myristic acid was first reacted
with propylene oxide, and then with epichlorohydrin. In both cases, the reactions were carried out at 150–1608C using
triethylamine as a catalyst. The obtained chloropropoxy-propoxy and propoxy-chloropropoxy esters of myristic acid are
non-ionic surfactants. These products were transformed into cationic surfactants by interaction with several ethanola-
mines. The specific electroconductance and surface activity of the obtained surfactants, characters that vary with the
colloidal–chemical parameters of the surfactants, depended on such factors as the sequence of the epichlorohydrin and
propylene oxide units inside the polar group of the obtained ionic surfactants, the presence of the methyl group linked to the
N-atom, as well as the number of ethylol groups. It was revealed that the synthesised surfactants possess a property of
localising thin (thickness ,1 mm) petroleum films spread over different types of water.
Manuscript received: 11 May 2018.
Manuscript accepted: 30 July 2018.
Published online:
4 September 2018.
Introduction
was smaller for the surfactant obtained by introducing PO units
first, then the EO units. Zhi-guo and Hong[14] have synthesised
surfactants based on dodecyl- and tridecyl alcohols which were
reacted with 1–4mols ofPOand8 mols ofEO. They mentionthat
an increase in the number of PO units in the hydrophilic group
leads to a CMC decrease. Yada and co-workers[15] have intro-
duced 4, 6, and 8 mols of EO followed by 1, 2, or 3 mols of PO
into C10, C12, C14, and C16 alcohols to synthesise new surfactants
(CnEOxPOy; n ¼ 10, 12, 14, or 16; x ¼ 4, 6, or 8; y ¼ 1, 2, or 3). It
was established that on incorporating 1–3 PO units to the
products havingeightEO units, their CMC values were increased
whereas the Gmax values were decreased. The surfactants based
on higher monocarboxylic acids having separate propoxy[4] and
chloropropoxy units[16] have been reported in the literature but
noinformation isgiven onthe synthesis ofthesurfactantsderived
from higher monocarboxylic acids containing both propoxy and
chloropropoxy fragments in the heterochain. The introduction of
ECH units into higher alcohols, higher amines, and higher
carboxylic acids enables the hydrophilicity of surfactants to
increase at the expense of CH2Cl group interactions with various
nucleophilic reactants.[17,18]
It is known that surfactants have several unique properties.
Depending on the structure of surfactants, their properties
vary.[1,2] Colloidal–chemical indices of surfactants vary
depending on the nature of their polar (hydrophilic) and non-
polar (hydrophobic) groups. The colloidal–chemical indices of
surfactants (i.e. the magnitudes of the critical micelle concen-
tration (CMC), maximum surface excess concentration (Gmax),
effectiveness or surface pressure (pCMC), and others) differ
depending on the length of the alkyl chain in the hydrophobic
part, the structure of the hydrophilic part, and the number of
polar groups.
Ethylene oxide (EO), propylene oxide (PO), and epichloro-
hydrin (ECH) are widely used in the production of various
surfactants.[3–6] In the surfactants obtained by reacting higher
alcohols or higher carboxylic acids with EO or PO, the sequence
of epoxy unit disposition in the hydrophilic part and the variation
ofthe numberof theseunits bringabout a changeintheproperties
of the surfactants.[7–12] Forgiarini et al.[13] first propoxylated
dodecanol in the presence of an alkaline catalyst and then
conducted ethoxylation. The number of both PO and EO units
equalled 7. They then added the same amounts of PO and EO to
dodecanol simultaneously. It was established that the CMC value
The present paper is dedicated to: i) the synthesis of non-
ionic surfactants based on myristic acid simultaneously
Journal compilation ꢀ CSIRO 2018
www.publish.csiro.au/journals/ajc

B
G. A. Ahmadova et al.
containing ECH and PO units, ii) conversion of these products
into cationic surfactants using five ethanolamines, and iii)
determination of the effect of the sequence of chloropropoxy
and propoxy unit incorporation and the structure of the ethanol-
amine on the resulting surfactant’s properties.
Determination of Surface Tension (g) at the Water–Air
Interface in the Presence of the Synthesised Surfactants
Surface tension at the water–air interface in the presence of the
synthesised surfactants was determined by a DuNouy ring KSV
Sigma 702 tensiometer (Finland). Measurements were made in
accordance with a literature procedure.[19] The surface tension
of distilled water used for preparing solutions equalled
72.0 mN mꢀ1 (258C).
Experimental
Reagents and Instruments
1H and 13C NMR spectra were recorded on a Bruker Avance
IIþ300 (UltraShield Magnet) spectrometer at 300.13 and
75.46 MHz using acetone-d6 as a solvent. FT-IR spectra were
determined on a Spectrum BX spectrometer using KBr disks. PO
(purity 99þ %, Alfa Aesar, Great Britain), ECH (purity 99 %,
Alfa Aesar, USA), myristic acid (purity 98%, Alfa Aesar GmbH
& Co KG, Germany), monoethanolamine(MEA) (purity . 99%,
Merck, Germany), diethanolamine (DEA, purity . 98.5%,
Merck, Germany), triethanolamine (TEA, purity. 99% Merck,
Germany), methyl monoethanolamine (MMEA, purity. 99%
Merck, Germany), and methyl diethanolamine (MDEA, purity
. 99%, Merck, Germany) were reagents of analytical grade.
Electroconductometric Measurements
The specific electroconductivity of the surfactant solutions was
measured using an ANION 4120 conductometer (Russia).
Measurements were conducted over the range of 10ꢀ4 to
10 S mꢀ1, and over a temperature range of 0–1008C with a
relative error not exceeding ꢁ 2 %. Measurements were made in
accordance with the literature procedure.[20] The specific elec-
troconductance of distilled water used for preparing the solu-
tions was in the range of 1.5–3 mS cmꢀ1
.
Study of Petrocollecting Properties of the Synthesised
Surfactants
The petrocollecting effectiveness of the surfactants was studied
using an unthinned reagent and its 5 wt-% aqueous solution (or
dispersion). The tests were carried out in three types of water
having various degrees of mineralisation (distilled, fresh, and
Caspian sea waters) using thin (thickness: 0.17 mm) layers of
Pirallahy petroleum (from the oil field near Baku, Azerbaijan, its
density being 0.9244 g cmꢀ3 at 208C and kinematic viscosity
equalling 1.05 cm2 sꢀ1 at 308C) according to the literature
procedure.[19] The petrocollecting coefficient (K) was deter-
mined as the ratio K ¼ S0/S, where S0 is the surface area of the
initial petroleum film and S is the surface area of the thickened
petroleum spot formed under the action of a reagent.
Synthesis of Surfactants Based on Myristic Acid and
Containing Propoxy–Chloropropoxy and
Chloropropoxy–Propoxy Units
The synthesis of myristic acid esters containing chloropropoxy
and propoxy units was conducted in two steps. First, in an
autoclave, triethylamine (5 mol-% of myristic acid) as a catalyst
and 0.1 mol of ECH were added to 0.1 mol of myristic acid. The
reaction was carried out at 150–1608C over 20–24 h. In order to
remove unreacted ECH, the reaction mixture was evaporated at
90–1008C until reaching a constant mass. According to the
obtained amount of reacted ECH, the conversion of ECH and
chloropropoxylation degree (m) were calculated. PO was then
added to the chloropropoxy ester and the reaction was continued
under the same conditions as for the chloropropoxylation. The
final product was separated from the by-products using a
microcolumn. The structure and composition of the synthesised
non-ionic surfactant was confirmed by NMR and IR spectros-
copy (Figs S1–S3, Supplementary Material).
The synthesis of myristic acid esters containing propoxy and
chloropropoxy units was also carried out in two steps. First, in an
autoclave, triethylamine (5 mol-% of myristic acid) as a catalyst
and 0.1 mol of PO were added to 0.1 mol of myristic acid. The
reaction was conducted at 150–1608C over 18–20 h. To remove
unreacted PO, the reaction mixture was evaporated at 40–508C
until attaining a constant mass. On the basis of the amount of
reacted PO, the conversion of PO and propoxylation degree (n)
were computed. ECH was then added to the propoxy ester and
the reaction was continued under the same conditions. Separa-
tion of the final product from the by-products was realised using
a microcolumn. The structure and composition of the obtained
non-ionic surfactant were identified by NMR and IR spectros-
copy (Figs S4–S6, Supplementary Material).
Results and Discussion
Synthesis of New Cationic Surfactants
New cationic surfactants have been synthesised using two
approaches (see Schemes 1 and 2), each consisting of three
steps. In the first two steps, myristic acid chloropropoxy–
propoxy (propoxy–chloropropoxy) esters were obtained, in the
third step, the CH2Cl group in these non-ionic surfactants was
reacted with five ethanolamines and, according to the qua-
ternisation scheme, cationic surfactants were obtained.
Critical Micellisation Concentration
For determination of the CMC, conductometric (measurement
of specific electrical conductance) and tensiometric (measure-
ment of surface tension) methods were used.
The surface tension of the aqueous solutions of different
concentrations of surfactants at the interface with air (258C) was
determined. According to the obtained values, surface tension
isotherms, i.e. dependences of g on concentration were con-
structed (Figs 1–5).
As is seen from the figures, with a rise in concentration of the
aqueous solutions of both ionic and non-ionic surfactants, the
surface tension gradually decreases down to gCMC. In the g ¼ f
(Csurfactant) isotherm, a curvilinear part corresponds to the region
of low concentrations of surfactants where, according to the
Gibbs equation, adsorption at the interface increases with an
increase of concentration. At a certain concentration, the curvi-
linear part of the isotherm passes to a straight line with a constant
value of dg/dlnC, i.e. the adsorption reaches a constant and
Synthesis of Cationic Surfactants on the Basis of Myristic
Acid (Chloro)Propoxy Esters
MEA (or DEA, TEA, MMEA, MDEA, 0.1 mol) was added to
0.1 mol of the myristic acid ester containing chloropropoxy and
propoxy units. The reaction was conducted at 608C over 6 h
using a magnetic stirrer with heating. The structure of the
obtained cationic surfactants were determined by NMR and IR
spectroscopy (Figs S7–S11, Supplementary Material).

Effect of Chloropropoxy and Propoxy Units on Surfactant Properties
C
O
O
O
ϩ
CH2
CH CH2Cl
C13H27
C13H27
C13H27
C13H27
C14
C
C
C
C
CH2 CH OH
OH
O
O
E
CH2Cl
O
C
ϩ
CH3
CH2
CH CH3
C13H27
O
CH2 CH OH
CH2Cl
CH2 CH
O
CH2 CH
O
H
O
EP
O
C14
CH2Cl
O
O
CH3
CH3
ϩ NR1R2R3
C13H27
C
H
O
CH2 CH
O
CH2 CH
O
O
CH2
H
C
O
CH2 CH
O H
ϩ
CH2Cl
NR1R2R3
CH2
C
lϪ
Scheme 1. The three steps of the first general synthesis: R1 ¼ R2 ¼ H, R3 ¼ CH2–CH2–OH (C14EPM); R1 ¼ H, R2 ¼ R3 ¼ CH2–
CH2–OH (C14EPD); R1 ¼ R2 ¼ R3 ¼ CH2–CH2–OH (C14EPT); R1 ¼ H, R2 ¼ CH3, R3 ¼ CH2–CH2–OH (C14EPMM); R1 ¼ CH3,
R2 ¼ R3 ¼ CH2–CH2–OH (C14EPMD).
O
O
O
ϩ
CH3
CH2
CH
C13H27
C
C13H27
C14
C
CH2 CH
CH3
O H
OH
O
P
O
O
ϩ
C13H27
C
CH2 CH CH2Cl
O
C13H27
C14PE
C
O
CH2 CH
CH3
O
H
O CH2 CH
CH3
O
CH2 CH OH
CH2Cl
O
O
C13H27
NR R R
ϩ
C13H27
C
C
1
2
3
O
CH2 CH
O
CH2 CH OH
O
CH2 CH
CH3
O
CH2 CH OH
ϩ
CH3
CH2Cl
CH2
ClϪ
NR1R2R3
Scheme 2. The three steps of the second general synthesis: R1 ¼ R2 ¼ H, R3 ¼ CH2–CH2–OH (C14PEM); R1 ¼ H, R2 ¼ R3 ¼ CH2–
CH2–OH (C14PED); R1 ¼ R2 ¼ R3 ¼ CH2–CH2–OH (C14PET); R1 ¼ H, R2 ¼ CH3, R3 ¼ CH2–CH2–OH (C14PEMM); R1 ¼ CH3,
R2 ¼ R3 ¼ CH2–CH2–OH (C14PEMD).
70
60
50
40
30
70
1
60
2
50
1
2
40
30
3
2
1
20
0.000001
0.00001
0.0001
0.001
20
0.000001
0.00001
0.0001
0.001
C [mol LϪ1
]
C [mol LϪ1
]
Fig. 2. Plot of surface tension at the water–air interface versus the
concentration of C14EPM (1), C14EPD (2), and C14EPT (3) cationic
surfactants.
Fig. 1. Plot of surface tension at the water-air interface versus the
concentration of C14EP (1) and C14PE (2) nonionic surfactants.
maximum level. At this part, a saturated monomolecular adsorp-
tion layer is formed at the interface. With a further increase of
surfactant concentration, micelles are created in the volume of
the solution and the surface tension does not practically change.
A straight line passing through the points of a stabilised value
(parallel to the C axis) and a straight line uniting points of
decreasing surface tension values have a point of intersection
which characterises the CMC value of the surfactant. Determi-
nation of surface tension enables estimation of the CMC value
for both ionic and non-ionic surfactants.

D
G. A. Ahmadova et al.
60
50
70
60
50
40
30
1
2
1
2
40
30
20
20
0.000001
0.00001
0.0001
0.001
0.000001
0.00001
0.0001
0.001
C [mol LϪ1
]
C [mol LϪ1
]
Fig. 5. Plot of surface tension at the water–air interface versus the
Fig. 3. Plot of surface tension at the water–air interface versus the
concentration of C14PEMM (1) and C14PEMD (2) cationic surfactants.
concentration of C14EPMM (1) and C14EPMD (2) cationic surfactants.
70
smaller than that for the C14EP-based ones. The corresponding
CMC values of the cationic surfactants formed based on C14PE
and MEA, DEA, or TEA are 14.0, 9.5, and 6.2 mol dmꢀ3. The
trend of CMC value decrease with the increase in the number of
ethylol groups is also observed in the case of the cationic
surfactants containing a methyl group bonded to the nitrogen
atom. Thus, the CMC values for C14EPMM and C14EPMD are
15.0 and 9.1 mol dmꢀ3, and for C14PEMM and C14PEMD are
13.6 and 9.1 mol dmꢀ3. In the case of these surfactants, an
augmentation of the number of ethylol fragments connected to
the N atom in the hydrophilic part also causes a decrease of the
CMC value. In the case of the cationics having similar hydro-
philic groups, the same trend is observed. For example, in the
salts obtained on the basis of dodecyl chloride, nonyl bromide,
and ethanolamines, as well as in the ammonium salts containing
dodecyl, tetradecyl, and hexadecyl hydrophobic groups and
having in the hydrophilic part a methyl group along with ethylol
groups, as the number of ethylol fragments bonded to the N atom
increases the CMC diminishes.[19,22,23]
When ECH is first added to myristic acid, the gCMC values for
both the ester itself and its salts are lower than those for C14PE
and its salts. For MEA, DEA, and TEA derived salts based on
C14EP, the gCMC values at the air–water interface are in the
range of 25.9–28.3 mN mꢀ1 whereas those values for the
analogous cationic surfactants obtained from C14PE fall into
the range of 26.6–30.0 mN mꢀ1. As the number of ethylol
groups in these samples rises, the gCMC value diminishes. In the
case of dodecylethylolammonium chloride and nonylethylo-
lammonium bromide salts having similar hydrophilic groups,
as the number of ethylol groups bonded to the N atom increases,
the gCMC value decreases.[19,22] However, in both types of salts
containing a methyl group, when passing from C14EPMM/
C14PEMM to C14EPMD/C14PEMD, the gCMC value increases.
2
1
60
3
50
40
30
20
0.000001
0.00001
0.0001
0.001
C [mol LϪ1
]
Fig. 4. Plot of surface tension at the water–air interface versus the
concentration of C14PEM (1), C14PED (2), and C14PET (3) cationic
surfactants.
It is known that the CMC value of ionic surfactants is ,10–
100-fold higher than that for non-ionic surfactants.[21] With an
increase of the number of separate ethoxy or propoxy units in the
hydrophilic fragment of the surfactants, the CMC value
decreases. However, in the case of the surfactants having both
EO and PO units, a very important factor is which epoxide starts
the heterochain. So, in the surfactant having a C12 chain and
eight ethoxy/propoxy units, the CMC value is significantly
impacted by which epoxide unit is located at the beginning of
the heterochain.[14]
As is seen from Table 1, when ECH is first added to myristic
acid (C14EP), the CMC value is larger. The CMC values for the
cationic surfactants subsequently obtained by adding MEA,
DEA, or TEA are 15.3, 10.9, and 9.9 mol dmꢀ3. When the
number of ethylol fragments linked to the N atom in the
hydrophilic part of the surfactant increases, the CMC value
decreases. The CMC values of the cationics based on C14PE are
Effectiveness (or Surface Pressure)
The surface pressure (pCMC) of the obtained surfactants at the
water–air interface was computed using Eqn 1:
pCMC ¼ g0 ꢀ gCMC
ð1Þ

Effect of Chloropropoxy and Propoxy Units on Surfactant Properties
E
Table 1. Colloidal–chemical parameters (258C) of the surfactants based on myristic acid, PO, and ECHA
Surfactants
b
G
max (ꢂ 1010
)
Amin (ꢂ 102)
CMCBtens (ꢂ 104)
CMCCelec (ꢂ 104) pC20
pCMC
[mN mꢀ1
gCMC
DGmic
[kJ molꢀ1
DGad
[kJ molꢀ1
]
[mol cmꢀ2
]
[nm2]
[mol dmꢀ3
]
[mol dmꢀ3
]
]
]
C14EP
—
1.87
1.53
2.40
2.52
2.97
1.18
1.40
1.92
2.35
2.65
1.66
1.98
88.7
108.3
69.1
2.11
1.05
1.53
1.09
0.99
1.50
0.91
1.40
0.95
0.62
1.36
0.91
—
4.88
5.56
4.68
4.85
4.83
5.82
5.65
4.94
4.92
5.11
5.21
5.02
45.4
43.0
43.7
44.8
45.1
46.1
45.6
43.0
43.7
44.7
45.4
42.0
26.6
29.0
28.3
27.2
26.9
25.9
26.4
29.0
28.3
27.3
26.6
30.0
ꢀ20.97
ꢀ22.70
ꢀ31.78
ꢀ33.68
ꢀ34.95
ꢀ30.98
ꢀ34.12
ꢀ29.24
ꢀ31.21
ꢀ33.85
ꢀ28.67
ꢀ31.12
ꢀ23.39
ꢀ25.50
ꢀ33.60
ꢀ35.46
ꢀ36.47
ꢀ34.90
ꢀ37.37
ꢀ31.49
ꢀ33.06
ꢀ35.53
ꢀ31.41
ꢀ33.24
C14PE
—
—
C14EPM
C14EPD
C14EPT
C14EPMM
C14EPMD
C14PEM
C14PED
C14PET
C14PEMM
C14PEMD
0.46
0.49
0.53
0.42
0.48
0.33
0.36
0.41
0.30
0.35
1.57
1.13
0.97
1.51
0.88
1.46
0.93
0.62
1.33
0.88
65.9
56.0
141.1
118.4
86.7
70.6
62.7
100.2
83.7
AThe standard uncertainties (u) are u(T) ¼ 0.1 K and u(p) ¼ 50 kPa. The combined expanded uncertainties (Uc) are Uc(b) ¼ 0.005, Uc(Gmax) ¼ 10ꢀ12 mol cmꢀ2
,
2
Uc(Amin) ¼ 0.5 A , Uc(CMC) ¼ 10ꢀ6 mol dmꢀ3, Uc(p) ¼ 0.1 mN mꢀ1, Uc(g) ¼ 0.1 mN mꢀ1 and Uc(pC20) ¼ 0.01 (0.68 level of confidence).
˚
BCMC found by tensiometric method.
CCMC found by electroconductometric method.
where g0 is the value of surface tension at the mentioned interface
without a surfactant, and gCMC is the value of the surface tension
at the CMC of the surfactant. The values of the synthesised
surfactant surface pressures are given in Table 1. As is seen from
the table, the value of the C14EP surface pressure is higher than
that for C14PE (45.4 v. 43.0 mN mꢀ1). The pCMC values of the
subsequently synthesised cationic surfactants increase as the
number of ethylol fragments increases from 1 to 3. An augmen-
tation of the pCMC values with an increase of the number of
ethylol groups linked to the N atom is also observed in other
cationic surfactants with similar headgroups.[19,22]
where dg/dlnC is the slope of the g ¼ f(lnC) plot in the region
before the CMC region, NA is Avogadro’s number, and n is the
pre-factor equalling 2 for cationics and 1 for non-ionics.
As is seen from Table 1, the Gmax values for the cationics
derived from C14EP and MEA, DEA, or TEA are higher than
those for the related cationics based on C14PE, but the Amin
values are lower. As the number of ethylol groups increases, the
Gmax value rises but the Amin value decreases. The latter two
trends are also observed for the synthesised cationics with an
additional CH3 group. Similar trends were recorded for non-
ylethylolammonium halides,[19] dodecylethylolammonium
chloride,[22] and dodecylmethylethylolammonium bromide
type[24] cationics, too. It should be mentioned that the presence
of an additional methyl group has resulted in the Gmax values for
C14EPMM and C14EPMD being smaller than for C14PEMM and
C14PEMD, whereas the Amin values for C14EPMM and
C14EPMD are higher with regard to the corresponding
C14PEMM and C14PEMD.
Adsorption Efficiency
The adsorption efficiency of the synthesised surfactants was
computed using Eqn 2:
pC20 ¼ ꢀ log CðꢀDg ¼ 20Þ
ð2Þ
In Table 1, the pC20 values for the synthesised surfactants are
shown. As is seen from the table, pC20 for C14PE is higher than
for C14EP. The pC20 values for C14EPM, C14EPD, and C14EPT
are lower than that for C14EP but the latter is smaller than those
for C14EPMM and C14EPMD. In the case of C14PE, its pC20
value exceeds those for all cationic surfactants based on it. The
cationic surfactants based on C14EP, with MEA, DEA, or TEA,
have lower values of pC20 than the respective cationics based on
C14PE, but when an additional methyl group is present, the
situation reverses. With an increase of the number of ethylol
fragments bonded to the N atom in the hydrophilic part, under
the action of a CH3 group, the pC20 value diminishes.
Conductivity Measurements
The specific electrical conductance of surfactants is one of the
significant indices for estimation of surfactivity and thermo-
dynamic indices. Conductometric determination of a CMC is
based on a change of the electroconductivity depending on an
ionic surfactant’s concentration. The specific electro-
conductivity of water solutions of the obtained cationics were
measured at different concentrations and the specific electro-
conductivity was plotted against concentration (Figs 6 and 7).
As is seen, with an increase of surfactant concentration, the
specific electroconductivity increases linearly and, after a cer-
tain concentration, a slope slightly decreases as a result of
micelle formation. A point of intersection of two straight lines
(below and after a break point) is considered the CMC. It is
evident from Table 1 that the CMC values for the cationics
found by tensiometric and conductometric methods differ
slightly. The ratio of the slopes after (S2) and before the CMC
(S1) is equal to a dissociation degree of the surfactant counterion
(a): a ¼ S2/S1. A binding degree of surfactant counterion (b) is
computed using the formula b ¼ 1 – a.[21]
Surface Excess Concentration (G) and Occupied Area per
Molecule (Amin
)
G
max, also called the maximum adsorption, of the obtained
surfactants at the water–air interface and the surface area per
molecule were calculated by Eqns 3 and 4:
1
dg
d ln C
Gmax ¼ ꢀ
lim
ð3Þ
ð4Þ
C!CCMC
nRT
The b values for the synthesised cationics are calculated and
given in Table 1. For cationic surfactants of both groups
Amin ¼ 1016=NAGmax

F
G. A. Ahmadova et al.
80
70
60
50
40
30
20
10
0
DGmic ¼ ð1 þ bÞRT ln CMC
ð6Þ
4
Changes of Gibbs free energies of the adsorption process of
the surfactants were computed by Eqn 7:[21]
5
1
DGad ¼ DGmic ꢀ 0:6023pCMCACMC
ð7Þ
2
The values of DGmic and DGad for the obtained surfactants
are given in Table 1. As is clear from the table, the values for
both processes are negative. It means that both processes occur
spontaneously. The DG values for micelle formation and
adsorption processes of the cationics are more negative than
for the respective non-ionic surfactants. With an increase in the
number of ethylol fragments in the surfactant molecules, their
adsorption and micellisation processes take place more readily.
The same trend is observed in the case of surfactants obtained
using ethanolamines containing a CH3 group.
3
0
0.5
1.0
1.5
2.0
2.5
C [ϫ 10Ϫ4 mol LϪ1
]
Petroleum-Collecting Properties of the Obtained Surfactants
Fig. 6. Plot of specific electrical conductivity of water solution versus
concentration of C14EPM (1), C14EPD (2), C14EPT (3), C14EPMM (4), and
C14EPMD (5) cationic surfactants.
The results of a study of the petroleum-collecting properties of
the non-ionics based on myristic acid, ECH, and PO are given in
Table 2. As is seen from the table, these surfactants have a high
petrocollecting capacity. When they are applied in unthinned
form, the largest petrocollecting capacity in all three (distilled,
fresh and sea) waters is demonstrated by C14EP (with maximum
values of petrocollecting coefficient K equal to 40.5, 40.5 and
30.3, the time of reagent action t being 144 h).
70
3
2
60
50
40
30
20
10
0
1
When these surfactants are used as a 5 wt-% aqueous
dispersion in the media of distilled and fresh waters, the highest
petrocollecting coefficient is shown by C14EP (in both waters
Kmax ¼ 40.5, t ¼ 144 h). In the case of sea water, C14PE is more
effective (Kmax ¼ 30.4, t ¼ 75 h).
4
5
The results of a study of the petrocollecting capacity of the
cationics based on C14EP and C14PE are given in Tables 3 and 4.
As is noticed from Table 3, the obtained surfactants demon-
strate a high petrocollecting ability over 7 days. When cationic
surfactants are applied in unthinned form, the largest petroleum-
collecting activity in the media of distilled and fresh waters is
demonstrated by C14EPMM and C14EPM (Kmax ¼ 75.9 and 60.7
in distilled water, Kmax ¼ 55.2 and 50.6 in fresh water, respec-
tively) and in sea water by C14EPMM (Kmax ¼ 75.9).
0
0.5
1.0
1.5
2.0
2.5
C [ϫ 10Ϫ4 mol LϪ1
]
When the synthesised C14EP-based salts are used as a 5 wt-%
aqueous dispersion, in distilled and fresh waters, the highest
petrocollecting capacity is manifested by C14EPM and
C14EPMM (for both salts in distilled water Kmax ¼ 50.6, in fresh
water Kmax ¼ 75.9), and in the sea water by C14EPMM
(Kmax ¼ 50.6).
Fig. 7. Plot of specific electrical conductivity of water solution versus
concentration of C14PEM (1), C14PED (2), C14PET (3), C14PEMM (4), and
C14PEMD (5) cationic surfactants.
As is seen from Table 4, the tests were carried out for a time
exceeding 6 days. When the cationics based on C14PE were used
in unthinned form, the largest petroleum-collecting activity was
shown in distilled water by the salts C14PEM and C14PED (for
both salts Kmax ¼ 40.5), in fresh water by C14PEM, C14PED, and
C14PET (for all of them Kmax ¼ 30.4), and in sea water by
C14PED (Kmax ¼ 22.7).
(without and with a methyl group), with an increase of ethylol
fragments, the b value rises. Ethylol groups negatively influence
the dissociation of the counter ion. For C14EP-based cationics,
the b value is higher than for the cationics synthesised from
C14PE. It may be concluded that the b value increases when a
hydrophilic cationic group passes to an inner part of the
heterochain.
When used as a 5wt-% aqueous dispersion, in distilled and
fresh waters, C14PET (corresponding Kmax ¼ 40.5 and 30.4) is
the most active whereas, in sea water, C14PED (Kmax ¼ 34.2)
shows the highest petrocollecting capacity.
Gibbs Free Energies for Micelle Formation and Adsorption
Processes of the Obtained Surfactants
The values of Gibbs free energies for the micellisation process
of the obtained non-ionics were calculated by Eqn 5 and those
for the cationics via Eqn 6:[21]
Thus, the synthesised ammonium-type salts have signifi-
cantly higher petrocollecting capability as compared with the
initial esters. A comparison of petrocollecting activities of the
cationics based on esters C14EP and C14PE shows that the ionic
DGmic ¼ RT ln CMC
ð5Þ
surfactants based on C14EP demonstrate
a
higher

Effect of Chloropropoxy and Propoxy Units on Surfactant Properties
G
Table 2. The results of the study of petroleum-collecting properties of C14EP and C14PEA (Pirallahy petroleum, thickness of the oil film: 0.17 mm)
Reagent
Distilled water
Fresh water
The Caspian sea water
t [h]
t [h]
K
t [h]
K
K
Unthinned surfactant
C14EP
0–24
40.5
30.3
0
2
40.5
30.3
22.7
17.2
18.5
17.2
0
30.3
23.2
16.9
26–144
2–24
24
26–144
48–144
0
C14PE
0–6
18.5
24.3
0–53
75
11.5
8.6
24–75
1–75
5 wt-% aqueous dispersion
C14EP
0–5
16.9
30.3
40.5
0
0.5
22.7
30.3
40.5
30.3
30.4
24.3
20.3
17.4
10.1
8.6
0
2
22.7
33.3
22.7
24–72
144
5–75
144
0–1
3–4
6–27
29–30
53
5–48
C14PE
0
1–6
24–53
75
18.5
20.3
30.4
12.2
0–1
3–6
30.4
15.6
12.2
11.1
8.7
24–27
29–30
53
75
75
3.1
AThe combined expanded uncertainty Uc is Uc(K) ¼ 0.2 (0.68 level of confidence).
Table 3. The results of the study of the petroleum-collecting properties of the cationics based on C14EP and ethanolaminesA (Pirallahy petroleum,
thickness of the oil film: 0.17 mm)
Reagent
Distilled water
Fresh water
The Caspian sea water
t [h]
t [h]
K
t [h]
K
K
Unthinned surfactant
C14EPM
0–1.5
60.7
16.9
0–0.5
1.5
55.2
33.3
16.9
22.7
16.9
0
22.7
15.2
20.5–150
1.5–168
20.5–150
0–1.5
C14EPD
C14EPT
0–0.5
1.5
30.3
17.2
15.2
40.5
30.3
23.2
16.9
75.9
33.3
30.3
30.3
17.2
16.9
0–168
22.7
21.5–150
21.5–150
0
0
30.3
22.7
16.9
0
30.3
22.7
16.9
0.5
0.5–48
72–144
0.5
2–4.5
24–144
0–0.5
1.5
2–144
C14EPMM
C14EPMD
0
0.5
50.6
22.7
16.9
24.3
22.7
15.2
0–26.5
44.5–71.5
96–168
0
60.7
75.9
22.7
24.3
17.3
10.1
8.6
48–150
0
1.5–150
0
0.5–2
24–144
0.5
0.5
2–144
2
5–24
5 wt-% aqueous dispersion
C14EPM
0
50.6
22.7
16.9
40.5
0–168
75.9
0
22.7
16.9
20.5
1.5–168
72–168
0–150
C14EPD
0
0.5–24
26.5
24.3
20.2
19.3
8.6
0–0.5
1.5
33.3
22.7
16.9
20.5–150
68.5–92.5
0
C14EPT
0–168
40.5
40.5
23.2
30.3
0
0.5
40.5
30.3
22.7
3.4
0.5–4.5
24–168
2–48
72–168
0
C14EPMM
C14EPMD
0
0.5–1.5
20.5
50.6
33.3
22.7
16.9
30.3
24.3
19.3
11.4
0
75.9
60.7
30.3
50.6
33.3
22.7
16.9
24.3
22.7
20.2
17.3
0.5
0.5
1.5–168
1.5
68.5–150
0–5
20.5–150
0
0–29
48–77
144
30.3
40.5
24
0.5–29
48
48
Spilled
72–144
77–144
AThe combined expanded uncertainty Uc is Uc(K) ¼ 0.2 (0.68 level of confidence).

H
G. A. Ahmadova et al.
Table 4. The results of the study of the petroleum-collecting properties of the cationics based on C14PE and ethanolaminesA (Pirallahy petroleum,
thickness of the oil film: 0.17 mm)
Reagent
Distilled water
Fresh water
The Caspian sea water
t [h]
t [h]
K
t [h]
K
K
Unthinned surfactant
C14PEM
0
40.5
24.3
22.7
30.4
40.5
30.4
15.6
24.3
20.3
11.8
15.6
11.5
0–73
145
30.4
3.9
0–3
5–49
73–145
0–1
14.1
16.9
7.6
1
3–145
0–5
C14PED
C14PET
0–1
3–49
73–145
0–1
24.3
30.4
15.2
30.4
24.3
20.3
17.2
22.7
11.2
17.2
14.1
28–49
1–5
73–145
0–1
28–145
0–6
3–4
3–53
75
24–75
6
24–75
0–1
C14PEMM
C14PEMD
0–1
3–4
6–75
0
15.6
17.2
11.4
18.5
17.2
11.5
0
1
14.1
8.6
7.6
9.3
8.6
5.7
3–24
3–24
0
0
1
15.6
14.1
11.5
1
1–4
6–24
3–75
3–75
5 wt-% aqueous dispersion
C14PEM
0–5
24.3
20.3
17.4
0
1–5
28–34
49
14.1
17.4
15.2
8.6
0–1
3–5
17.2
14.1
13.5
6.1
28–49
73–145
28–34
49–145
0
C14PED
0
1
13.5
17.4
8.6
0
14.1
7.5
34.2
24.3
17.4
3.9
1–5
28–30
1–3
3–32
2.2
5
28–49
0–24
27–75
C14PET
0–75
40.5
0–1
3–6
30.4
24.3
13.5
11.5
4.0
14.1
2.0
24–75
0–6
C14PEMM
0–6
24
12.0
20.3
17.4
13.5
8.6
0–3
4–6
11.5
9.3
24–75
27
24–27
6.8
29–30
53–75
0–6
C14PEMD
11.8
13.7
24.3
0–6
11.5
3.4
0–6
11.5
2.0
24
24–27
29–75
24–75
29–75
2.7
AThe combined expanded uncertainty Uc is Uc(K) ¼ 0.2 (0.68 level of confidence).
petrocollecting capacity. When these salts are used as unthinned
reagents and 5 wt-% aqueous dispersions, in all three waters, the
highest petrocollecting effectiveness is manifested by the salt
C14EPMM.
increases. The surfactants on the basis of C14EP possess stronger
petrocollecting properties.
Supplementary Material
IR, 1H NMR, and 13C NMR spectra of synthesised surfactants
(Figs S1–S11) are available on the Journal’s website.
Conclusion
Using myristic acid, PO, and ECH, two ester-type non-ionic
surfactants were obtained and then transformed into cationic
surfactants through the quaternisation scheme using ethanola-
mines. The surface activity properties of the obtained cationics
were comparatively investigated. It was established that, for the
surfactants having a propoxy unit at the beginning of the het-
erochain, the CMC value is smaller. For the cationic surfactants
of both groups, with a rise in the number of ethylol groups in the
hydrophilic fragment, the magnitudes of CMC, Amin, and gCMC
decline whereas the values of b, Gmax, pC20, and pCMC increase.
Among the surfactants having methyl groups along with ethylol
fragments, with an increase in the number of ethylol groups, the
values of pC20 and pCMC diminish whereas the gCMC value
Conflicts of Interest
The authors declare no conflicts of interest.
Acknowledgements
The publication was prepared with the support of the ‘RUDN University
Program 5-100’. The authors thank the Institute of Petrochemical Processes
of National Academy of Sciences of Azerbaijan for supporting this research.
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