Synthesis and application exploration of novel gemini surfactant

Article abstract of DOI:10.14233/ajchem.2015.17075

A novel gemini surfactant dichloride- N,N,N′,N′-tetramethyl-N,N′-dicetyl-2-propanol-1,3-ammonium (DTDPA) with two hydrocarbon chains connected by hydroxyl spacer chain was synthesized by three steps reactions. The values that characterized the solution properties of gemini surfactant including critical micelle concentrations (cmc), γcmc, pC20 and cmc/C20 were measured. The results demonstrated that the gemini surfactant gave low cmc, great efficiency in lowering the surface tension and strong adsorption at air/water interface. The application of DTDPA in the field of enhanced oil-recovery (EOR) technology and suspension copolymerization was investigated. DTDPA can reduce the interfacial tension of crude oil-water system sharply and maintain the viscosity of surfactant-PAM system excellently. The addition of DTDPA as assistant dispersant system can promote the oil absorption capacity of resin prepared by suspension copolymerization method within a range of concentration and reduce the oil absorption balanced time as increasing concentration of gemini surfactant.

Full text of DOI:10.14233/ajchem.2015.17075

Asian Journal of Chemistry; Vol. 27, No. 2 (2015), 609-612
ASIAN JOURNAL OF CHEMISTRY
http://dx.doi.org/10.14233/ajchem.2015.17075
Synthesis and Application Exploration of Novel Gemini Surfactant
3
4
XI-YUAN WU1,2,*, HUI WANG and GUI-RONG WANG
1State Key Laboratory of Soil Erosion and Dryland Farming in the Loess Plateau, Institute of Water and Soil Conservation Chinese Academy
of Sciences and Ministry of Water Resources, Northwest A&F University, Yangling 712100, Shaanxi Province, P.R. China
2Shandong Provincial Key Laboratory of Water and Soil Conservation and Environmental Protection, Linyi University, Linyi, Shandong, P.R. China
3Department of Chemical Engineering, University of Waterloo, 200 University Ave. West, Waterloo, Ontario, N2L 3G1, Canada
4Hangzhou Raw Seed Growing Farm, Hangzhou, P.R. China
*Corresponding author: Fax: +86 539 8766700; Tel: +86 15653975739; E-mail: wuxiyuan616@yahoo.com
Received: 18 January 2014;
Accepted: 24 February 2014;
Published online: 10 January 2015;
AJC-16629
A novel gemini surfactant dichloride- N,N,N',N'-tetramethyl- N,N'-dicetyl-2-propanol-1,3-ammonium (DTDPA) with two hydrocarbon
chains connected by hydroxyl spacer chain was synthesized by three steps reactions. The values that characterized the solution properties
of gemini surfactant including critical micelle concentrations (cmc), γcmc, pC20 and cmc/C20 were measured. The results demonstrated
that the gemini surfactant gave low cmc, great efficiency in lowering the surface tension and strong adsorption at air/water interface. The
application of DTDPA in the field of enhanced oil-recovery (EOR) technology and suspension copolymerization was investigated. DTDPA
can reduce the interfacial tension of crude oil-water system sharply and maintain the viscosity of surfactant-PAM system excellently. The
addition of DTDPA as assistant dispersant system can promote the oil absorption capacity of resin prepared by suspension copolymerization
method within a range of concentration and reduce the oil absorption balanced time as increasing concentration of gemini surfactant.
Keywords: Gemini surfactant, EOR, Surfactant-polymer system, Suspension copolymerization, Resin, Oil absorption capacity.
quaternary ammonium gemini surfactants, which show more
efficiency in reducing surface tension of water and interfacial
tension at oil/water interface and stronger adsorption at solid/
INTRODUCTION
Since Bunton et al.1 synthesized the cationic types of
gemini surfactants, alkanediyl-α,ω-bis(alkyldimethyl-
ammonium) dibromide1 and the gemini surfactant have been
the most investigated surfactants.
solution interface9,10
.
Enhanced oil-recovery (EOR) is a low-cost sources of
new oil reserves and play a key role in maintaining steady oil
production and long-term enhanced oil-recovery prospects
remain good11. The alkali-surfactant-polymer (ASP) system
is the most important techniques of enhanced oil-recovery
realization. However, alkali existence cause increased amount
of polymer, which need a large capital investment. Meanwhile,
alkali can damage oil reservoir via scaling in underground
wells. It is significant to figure out how to replace alkali-surfac-
tant-polymer system using surfactant-polymer (SP) system or
reduce the proportion of alkali in alkali-surfactant-polymer
system.
The gemini or dimeric surfactants with two hydrocarbon
chains and two hydrophilic groups connected by spacer chain
have been investigated actively2-8. The surfactants have superior
properties compared with conventional monomeric surfactants,
such as low critical micelle concentration (cmc) and C20
(surfactant concentration in the solution phase that can reduce
the surface tension of the solvent by 20 mN m-1)2-4. In addition,
the gemini surfactants are capable of increasing linear and
branched thread-like micelles as well as closed ring micelles
at extremely low concentrations. Gemini surfactants with short
spacer groups even have unusual rheological properties4,5,
which bring gemini surfactants more research significances
recently6-8.
In polymer chemistry field, the key step in suspension
copolymerization process is to form and control the suspended
particles. The addition of proper dispersant comprising surfac-
tant will help to promote the performance of aimed polymer
products.
However, there were few reports concerning the appli-
cation of gemini surfactants in the fields which were dominated
by monomeric surfactants. It is important to promote the
practical application as well as synthesis and physicochemical
properties research of gemini surfactant, especially the
We synthesized symmetric gemini quaternary ammonium
salt cationic surfactant dichloride- N,N,N',N'-tetramethyl- N,N'-
dicetyl-2-propanol-1,3-ammonium (DTDPA) by three-step

610 Wu et al.
Asian J. Chem.
CH3
H3C NH Cl
C16H33
H3C
HCl
H3C
N
+
C16H33
CH3
CH3
H
C
n-propanol
H
H2C
CH2
Cl
H3C
Cl
Cl H3C
CH2
CH2
C
NH
N
+
O
OHCl
C16H33
C16H33
CH3
H2
CH3
H3C
CH3
H2
C
H
Cl
CH3
Cl H3C
HC
N
C
N
CH3
+ N
Cl H3C
CH2 CH2
C
N
OH
C16H33
C16H33
OHCl
C16H33
C16H33
Scheme-I: Synthesis reaction routes of Gemini surfactant DTDPA
reactions and investigated the potential application capability
in the surfactant-polymer system of enhanced oil-recovery
technology and preparation oil absorbency resin by suspension
copolymerization as part of the dispersant system.
Scheme-I shows the reaction route for the synthesis of
DTDPA used in this study.
negative value (pC20) of logarithm of surfactant concentration
C20 and the value of cmc/C20 ratio2, respectively. The pC20
measures the efficiency of surface adsorption and cmc/C20
ratio is a trending measure of surfactant to adsorb at the air/water
interface related to its tendency to form micelles in the solution2.
Suspension copolymerization: A type of polyacrylate
high oil absorbency resin was prepared by suspension copoly-
merization technology. Polyvinyl alcohol and DTDPA com-
posite system were as dispersant first time, ethyleneglycol
dimethacrylate as crosslinking monomer, lauryl acrylate as
monomer initiated by benzoyl peroxide, paraffine as fillers to
promote the absorption performance. The optimized recipe
was as follows: the ratio of DTDPA and PVA is 2:3, LA:
EGDMA: BPO = 100:1:2. The whole experiment process was
conducted under protection of nitrogen.
EXPERIMENTAL
Dimethylcetylamine, epichlorohydrin (ECH), n-propanol,
acetone, ethyl acetate, polyvinyl alcohol (PVA), benzoyl
peroxide (BPO), ethyleneglycol dimethacrylate (EGDMA),
lauryl acrylate (LA) and polyacrylamide (PAM) were purchased
from Huadong Medicine Co., Ltd. (Hangzhou, China). They
were used without further purification.All of the other chemicals
used were of reagent grade. Triply distilled water was used in
all of the measurements.
Methodologies of oil absorption experiments: The
performance of oil sorbent is commonly rated by its absorption
weight per unit weight (g/g)12. The procedure for determining
oil absorption capacity generally followed the standard method
defined by the American Society for Testing and Materials
(ASTM)13. The oil absorbency was calculated according to
the following equation:
Synthesis of DTDPA: The dimethylcetylamine was added
to the stirred mixture solution of distilled water and hydro-
chloric acid the speed of 5-7 drops per minute. The temperature
was maintained at 45 °C using digital circulating water bath.
The mixture was refluxed reaction for 3 h. The intermediate
products were produced at 70 °C with added n-propanol to
intermediates mixture. Then, ECH was added to mixture at
the speed of 15-50 drops per minute. The mixture was refluxed
for 1 h, the dimethylcetylamine was added to the reaction which
was carried out for 6 h. The raw compound was washed using
acetone and then recrystallized triply from mixtures of acetone
and ethyl acetate. The aimed-compound as white solid was
obtained after low temperature vacuum drying. The yield was
51.60 %. The structure was confirmed by FTIR (NICOLET
560 ESP). There were ν(O-H) in 3425.98 cm-1, ν(-CH3) in
2918.09 cm-1, ν(-CH2-) in 2850.11 cm-1, δ(C-H) in 1467.93
cm-1 and no δ(C-N) in 1220-1020 cm-1, which showed the
dimethylcetylamine had reacted completely into DTDPA. The
melting point was 73 °C, which was obtained by TG-DTA-
DTG analyses (Beijing Optical Instrument Factory WCT-2).
Equilibrium surface tension: the surface tension of aqueous
solutions was measured with drop volume method. Sets of
measurements to obtain equilibrium surface tension were taken
until surface tension was changed less than 0.05 mN m-1 per
5 min. The cmc was obtained from the breakpoint of logarithm
curve of surface tension versus concentration. Surface tension
at cmc (γcmc) and C20 were also showed by the curve. The
efficiency and effectiveness can be characterized by the
WT − WC − WA
Oil Absorbency Capacity (W) (g/g) =
(1)
WA
where WT is the total weight (g) of the oil, test container and
absorbent, WC is the weight of test container (g) and WA is the
dry weight of absorbent (g)14.
RESULTS AND DISCUSSION
Equilibrium surface tension: Table-1 shows the diffe-
rence of equilibrium surface tension between gemini surfactant
DTDPA and the conventional typical monomeric surfactants.
Table-1 lists the values of the cmc, surface tension at cmc
(γcmc), pC20 and cmc/C20 along with the data of typical
monomeric surfactant of sodium dodecyl benzene sulfonate
(SDBS), the anionic monomeric surfactant sodium dodecyl
sulfate (SDS) and the cationic monomeric surfactant trimethyl
dodecyl ammonium bromide (TDAB).
As expected, DTDPA provides lower cmc and higher
efficiency in lowering the surface tension than the monomeric
surfactants. It is notable that the cmc of DTDPA is smaller by
two or three orders of magnitude approximately than that of
monomeric surfactants. This suggests the present gemini
surfactants make it easy to form micelles in the bulk solution.

Vol. 27, No. 2 (2015)
Synthesis and Application Exploration of Novel Gemini Surfactant 611
100
TABLE-1
COMPARISONS BETWEEN DTDPA AND
TYPICAL MONOMERIC SURFACTANTS
10
1
cmc
(mol L-1)
8.00 × 10-4
1.20 × 10-3
8.00 × 10-3
γcmc
(mN m-1)
31.50
Surfactants
pC20
cmc/C20
DTDPA
SDBS
3.82
3.30
2.39
-
5.33
2.40
1.95
-
0.1
32.55
C12H25SO4Na
C12H25N(CH3)3Br 1.60 × 10-2
38.00
0.01
40.00
0.001
0.0001
0.00001
The efficiency and effectiveness can be characterized by
value of pC20 and cmc/C20, respectively. The pC20 value
measures the efficiency of adsorption of surfactant at the air/
water interface. Larger value of pC20 leads to greater tendency
of surfactant to adsorb at air/water interface, related to its
tendency to form micelles and it reduces the surface tension
more efficiently. The value of cmc/C20 ratio is a convenient
way to measure, which can be correlated with structural factors
on the micellization and adsorption processes. Larger values
of cmc/C20 ratio also lead to greater tendency of surfactant to
adsorb at the interface, related to its tendency to form micelles2.
The value of pC20 of DTDPA is larger than those of mono-
meric surfactants of SDBS, TDAB and SDS. It can be explained
that longer hydrocarbon chains of the gemini surfactants lead
to stronger adsorption at the air/water interface. The values of
cmc/C20 of DTDPA are much high than those of monomeric
surfactants. This indicates gemini surfactants adsorb at the air/
water interface easier and larger cmc/C20 ratio probably
reflects the difficulties of packing two hydrophobic groups in
micelle.
-1
0
1
2
3
4
5
6
7
8
9
10
DTDPA concentration (g L–1)
Fig. 1. Interfacial tension between crude oil and water at different
concentration of DTDPA
system compared with the monomeric surfactant and also it
has a high potential to be used in surfactant-polymer (SP) and
even as a single component without other additives which
would avoid chromatographic separation, which will be used
in surfactant flooding more widely. Therefore, the research
of gemini surfactants is very important and significant for both
theories and practices.
Viscosity variation research of surfactant-polymer
system: In order to investigate the feasibility of the surfactant-
polymer system further to replace the alkali-surfactant-polymer
system, it is necessary to study the viscosity variation of gemini
surfactant and polymer binary system. The polyacrylamide
(PAM) was chosen as the experimental polymer because PAM
is the most widespread and efficient used polymer in polymer
flooding field. The PAM solution with 1000 ppm was prepared
and viscometer (Haake RV-20) was implemented to measure
viscosity variation in 30 days of the binary system with diffe-
rent concentration of gemini surfactant (Fig. 2). Fig. 2 shows
that the viscosity of binary system decreases with the increases
of DTDPA concentration. The binary viscosity decreases with
the days passed by. The viscosity loss of binary system in 30
days is demonstrated in Table-2. The values show that the
gemini surfactant-polymer system is efficient in viscosity
maintenance capability.
Application research of DTDPA in the enhanced oil-
recovery technology
Effect of DTDPA on equilibrium interfacial tension
of crude oil-water system: Fig. 1 show the variation of the
equilibrium interfacial tension (IFT) of crude oil-water system
as the increase concentration of gemini surfactant DTDPA. In
order to make the experiment results more close to the real
gemini surfactant flooding application conditions, crude oil
from Shengli Oil Field (East China) was used.
Fig.1 shows that the interfacial tension of oil-water system
can be reduced sharply to ultra-low level (< 10-4 mN m-1) with
a wide range from 50 to 0.007 mN m-1 until the DTDPA
concentration reaches 2 g L-1. At 2 g L-1 of DTDPA concen-
tration, there is a minimal value of interfacial tension of oil-
water system as as 10-5. The interfacial tension increases a bit
as the increases of DTDPA with the concentration of DTDPA
more than 2 g L-1. It can be explained as follows: the ingredient
of crude oil is more complex than the oil on sale and crude oil
contains few interface activity materials, which can take
synergistic effect with gemini surfactants in reducing interfacial
tension of crude oil-water and at a certain surfactants concen-
tration. It can keep the interfacial tension lower.
Application research of DTDPA in suspension copoly-
merization: The types, properties and amount of the dispersant
are critical to determine the resin particle diameters and other
characteristics and further to influence the performance of the
DTDPA concentration 0.10 g L–1
DTDPA concentration 0.30 g L–1
DTDPA concentration 0.05 g L–1
DTDPA concentration 0.20 g L–1
500
450
400
350
300
250
200
At present, surfactant flooding is very complex and has
the highest degree of uncertainty. If the surfactant formulation
for enhanced oil-recovery (EOR) is properly designed and
the flow of the formulation is properly controlled in the oil
reservoir, it has a high potential for achieving maximum oil
recovery (MOR).As gemini surfactant has obvious advantages
in reducing the equilibrium interfacial tension of oil-water
5
0
10
15
20
25
30
Time (days)
Fig. 2. Variation of viscosity of surfactant-polymer system with DTDPA
concentration

612 Wu et al.
Asian J. Chem.
TABLE-2
LOSS OF VISCOSITY OF
SURFACTANT-POLYMER SYSTEM (30D)
Fig. 3 also indicates that there is a maximum oil absorption
capacity with the variation of DTDPA concentration from 0
to 0.15 wt. %. It means an optimum DTDPA concentration in
the preparation process of the high oil absorption resin.
CDTDPA (g L-1)
0.050
22.22
0.10
0.20
0.30
Loss percentage (%)
23.17
25.33
28.57
Conclusions
oil absorption resin. However, the single dispersant is not
enough to satisfy the requirements to prepare the excellent
performance absorbents. For example, the polyvinyl alcohol
(PVA) is a commonly used dispersant, but PVA has lower
capability to reduce the equilibrium surface tension. When
the concentration of PVA is 0.1-0.2 wt. %, the surface tension
of solvent reach 50-60 mN m-1. Therefore, it is necessary to
add surfactant to the reaction system to reduce surface tension.
When DTDPA is added into the reaction system, it mainly
plays roles in two aspects. DTDPA increases the adhesive effect
of medium so that the particles have fewer chances to adhere
each other. Meanwhile, resin's diameter can reach much smaller
range as the reduction of surface tension.
• The cmc, γcmc, pC20 and cmc/C20 showed gemini
surfactant has quite low cmc and can reduce surface tension
efficiently. In addition, gemini surfactant was adsorbed at the
air/water surface rather than form the micelles.
• The DTDPA-PAM system has better feasibility to replace
alkali-surfactant-polymer system based on its excellent crude
oil-water system interfacial tension reduction and viscosity
maintenance.
• As one component of dispersant system in suspension
copolymerization, DTDPA can assist the PVA to disperse the
monomer particles evenly and promote resin performance
characterized by oil absorption capacity and balanced time.
ACKNOWLEDGEMENTS
Crude oil from Shengli oil field (East China) was used to
be test oil. Fig. 3 shows the effects of different concentrations
of gemini surfactant on the oil absorption capacities and rates
of absorbents. It shows that the absorption oil balanced time
of absorbent decreases with the increases of the concentration
of DTDPA. There is no addition of DTDPA, so it need more
than 100 min when concentration of DTDPA reaches 0.15
wt. %, it needs less than 50 min.
The research was supported financially by the Open Fund
of State Key Laboratory of Soil Erosion and Dryland Farming
on the Loess Plateau (No. 10501-1208).
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DTDPA 0.00 wt %
10
DTDPA 0.05 wt %
DTDPA 0.10 wt %
5
DTDPA 0.15 wt %
0
0
50
100
150
200
250
300
Time (min)
Fig. 3. Effect curve of DTDPA concentration on the oil absorption capacity
of resin. EGDMA = 0.4 wt. %, BPO = 0.8 wt. %, PVA = 0.15 wt. %