Investigation on interfacial/surface properties of bio-based surfactant N-aliphatic amide-N,N-diethoxypropylsulfonate sodium as an oil displacement agent regenerated from waste cooking oil

Article abstract of DOI:10.1016/j.molliq.2016.08.026

To regenerate the non-edible waste cooking oil and significantly reduce the negative effect on human being and the environment, a bio-based nonionic-anionic amphoteric sulfonate type surfactant with excellent interfacial and surface properties was synthesized. The interfacial tensions between crude oil and water can reach up to an ultralow value as 0.0040?mN·m^??1 without additives. With dynamic light scattering and surface tension, micelles formed by N-aliphatic amide-N,N-diethoxypropylsulfonate bio-based surfactant were studied. This work also systematically investigated the surface activity, adsorption behavior, and thermodynamic parameters (ΔG_m⁰, ΔG_ads⁰, ΔH_m⁰, ΔS_m⁰, ΔH_m^A, ΔC_p,m⁰) of micellization. According to the experimental results, it can be seen that the bio-based surfactant has an excellent surface activity, besides, the micelle formation is entropy and enthalpy co-driven at 25–45?°C. Dynamic light scattering also illustrated the micelle formation. Through this research work, we expect to gain some insights into the phase behaviors of this bio-based surfactant and broaden its great potential oilfield application in enhanced oil recovery.

Full text of DOI:10.1016/j.molliq.2016.08.026

Investigation on interfacial/surface properties of bio-based surfactant N-
aliphatic amide-N,N-diethoxypropylsulfonate sodium as an oil displacement
agent regenerated from waste cooking oil
Yan Zhang, Qing You, Yang Fu, Mingwei Zhao, Hongfu Fan, Yifei Liu,
Caili Dai
PII:
DOI:
Reference:
S0167-7322(16)31738-X
doi: 10.1016/j.molliq.2016.08.026
MOLLIQ 6186
To appear in:
Journal of Molecular Liquids
Received date:
Accepted date:
29 June 2016
7 August 2016
Please cite this article as: Yan Zhang, Qing You, Yang Fu, Mingwei Zhao, Hongfu
Fan, Yifei Liu, Caili Dai, Investigation on interfacial/surface properties of bio-based sur-
factant N-aliphatic amide-N,N-diethoxypropylsulfonate sodium as an oil displacement
agent regenerated from waste cooking oil, Journal of Molecular Liquids (2016), doi:
10.1016/j.molliq.2016.08.026
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ACCEPTED MANUSCRIPT
Investigation on Interfacial/Surface Properties of Bio-based Surfactant
N-Aliphatic Amide-N,N-Diethoxypropylsulfonate Sodium as An Oil
Displacement Agent Regenerated from Waste Cooking Oil
Yan Zhang1,2, Qing You1*, Yang Fu2, Mingwei Zhao2, Hongfu Fan1, Yifei Liu2, Caili
Dai2*
1. School of Energy Resources, China University of Geosciences (Beijing)
2. School of Petroleum Engineering, China University of Petroleum (East China)
-------------------------------
*Corresponding authors:
Qing You, Tel 86-10-82322754, Email youqing@cugb.edu.cn
Caili Dai, Tel 86-532-86981183, Email daicl@upc.edu.cn
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ABSTRACT: To regenerate the non-edible waste cooking oil and significantly
reduce the negative effect on human being and the environment, a bio-based
nonionic-anionic amphoteric sulfonate type surfactant with excellent interfacial and
surface properties was synthesized. The interfacial tensions between crude oil and
water can reach up to an ultralow value as 0.0040 mN/m without additives. With
dynamic light scattering and surface tension, micelles formed by N-aliphatic amide-N,
N-diethoxypropylsulfonate bio-based surfactant were studied. This work also
systematically investigated the surface activity, adsorption behavior, and
0
0
0
A
thermodynamic parameters (ΔGm , ΔGads0, ΔHm , ΔSm , ΔHm , ΔCp,m0) of
micellization. According to the experimental results, it can be seen that the bio-based
surfactant has an excellent surface activity, besides, the micelle formation is entropy
and enthalpy co-driven at 25-45oC. Dynamic light scattering also illustrated the
micelle formation. Through this research work, we expect to gain some insights into
the phase behaviors of this bio-based surfactant and broaden its great potential oilfield
application in enhanced oil recovery.
Keywords: bio-based surfactant, ultralow interfacial tension, surface activity, micelle
formation, thermodynamic parameters
2

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1. Introduction
Crude oil as industrial blood is the most important natural resource of the world.
However, approximately two-thirds of the oil remains in an average oil reservoir after
primary and secondary (water flooding) oil recovery. The residual oil is trapped in the
reservoir pore structures due to capillary forces, which could be displaced by
increasing microscopic displacement oil efficiency. Reducing the oil-water interfacial
tension (IFT) is one of the most effective ways to remarkably increase the efficiency
of oil recovery when the IFT value between the displacing fluid and crude oil reaches
up to an ultralow level (<10-2 mN·m-1) [1]. Many researches have been done to
investigate the mechanism of surfactant flooding [2,3]. The reduction of oil-water
interfacial tension is a principal mechanism for surfactant system to enhance oil
recovery. Anionic surfactant (such as petroleum sulfonate with extensive source and
lower cost advantage), nonionic surfactant (such as containing ethylene oxide group
with high stability according to the different needs), and zwitterionic surfactant (such
as betaine with good temperature resistance, salt tolerance and biodegradation) have
been widely used in enhanced oil recovery [4, 5]
.
The surfactants mentioned above are mainly petroleum-based surfactants, which
have the problems of the easy hydrolysis and bio-refractory for the environment. In
addition, the huge consumption of the surfactant has reached about 10×106 tons, but
mostly from petroleum-based surfactant, for an example, the proportion of the total
amount of the surfactant in China is up to 85%. Due to the shortage of nonrenewable
petroleum resources, both scientific and industries fields have noticed the
bio-surfactant with renewable supplies and environmentally friend application.
Especially in recent years, some of the bio-based surfactants derived from waste
cooking oils have been reported and becomes a major focus for researchers [6-10]
.
As a sort of inedible oil, waste cooking oil has huge quantities, according to the
statistics, around 4×106-6×106 tons of waste cooking oils was generated from urban
food waste in China per year. Unreasonable dispose of waste cooking oil harms the
environment and human beings. For an example, if disposed into the rivers, it not only
results in waste, but also pollutes the water resources. In addition, some of them went
back to the dining table by refining, which caused a serious threat to food security. As
an inedible animal and vegetable oil, waste cooking oil contains abundant organic
matter, so it is an important substitute resource for petroleum [11]
.
At present, the reutilization of the waste cooking oil mainly involves the
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preparation of biological demulsifier, washing raw materials, fatty acid methyl esters
(biodiesel), textile additives, etc [12-18]. As the most mature research area among them,
the biodiesel preparation can not only be used as a new, clean and renewable
bio-based energy resource, but can also act as a research basis of the non-toxic,
harmless, degradable bio-based surfactants in some industrial fields, especially, in
enhanced oil recovery area, the application can substitute for petroleum-based
surfactants. In this case, in surfactant production, the proportion of all
petroleum-based surfactants is gradually dropping off. The synthesis as well as
interfacial activities of bio-based zwitterionic surfactant which is applied in enhanced
oil recovery field have been studied [19]. However, to our best knowledge, the research
about bio-based nonionic-anionic amphoteric sulfonate type surfactants derived from
waste cooking oil and their utilization in enhanced oil recovery field is a virgin land to
be exploited.
In this work, a bio-based nonionic-anionic amphoteric sulfonate type surfactant is
synthesized. The surface/interfacial activity, adsorption property, and thermodynamic
parameters of micellization of the bio-based surfactant are systematically investigated.
Through this research work, we expect to gain some insight into the phase behaviors
of this bio-based surfactant and broaden its great potential application area in
enhanced oil recovery. Furthermore, this work also provides an important strategic
significance for national energy security.
2. Experimental Section
2.1 Chemicals
Waste cooking oil was collected from canteens and restaurants. Filtration and
centrifugation was performed and it acidified and filtered the upper oil phase. Besides,
the upper oil phase was also, dehydrated and washed by water. The raw material was
got and was used to prepare fatty acid methyl ester[20-22]. The average carbon chain
length of fatty acid methyl ester is 12 by 1H NMR method, the average formula is
C11H23COOCH3. The bio-based N-aliphatic amide-N, N-diethoxypropylsulfonate
sodium (NDPSS) was synthesized through two-step reactions below [23]
:
(1) Synthesis of fatty acid alkanolamide
The raw materials fatty acid methyl ester and diethanolamine (mole ratio: 1:1.1)
were mixed and reacted at 100℃ for 5 h. NaOH was used as a catalyst with mass
concentration of 0.5 wt %.
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O
O
C
CH2CH2OH
CH2CH2OH
C11H23
CH2CH2OCHhemPaster
+ CH3OH
+
C
OCH3
N
C11H23
NH
CH2CH2OH
After the reaction, the solution was concentrated in rotary evaporator. After drying,
the fatty acid alkanolamide is obtained. The yield is 85%.
(2) Sulfopropyl reaction
The reaction materials fatty acid alkanolamide and 1,3-propanesultone (molar ratio:
0.52:1) reacted at 80℃ for 24 h. NaOH was used as a catalyst with mass
concentration of 0.8 wt %.
O
O
O
O
C
O
C
CH2CH2OH
CH2CH2OH
S
CH2CH2OCH2CH2CH2SO3Na
CH2CH2OCH2CH2CH2SO3Na
N
+
2
R
+ 2H2O
N
+ 2NaOH
R
After the reaction, the solution was cooled and dried in rotary evaporator. Finally,
the pale yellow solid powders was obtained and its yield is 88%. Then, the NDPSS
1
was characterized with 1H NMR shown in support information. H NMR (400 MHz,
-
D2O, 298 K) d: 3.89 (m, 4H), 3.44–3.35 (m, 8H), 2.96 (t, 4H, CH2-SO3 ), 2.15 (t, 2H),
1.82 (m, 2H), 1.39 (m, 2H), 1.18–1.10 (m, 16H, alkyl chain), 0.81 (t, 3H, -CH3); IR:
2924.94 cm-1(−CH3), 2853.89 cm-1 (−CH2), 1620.61 cm-1 (−CO), 1347.15 cm-1
(−CON), 1167.72 cm-1 (C−O−C), 1192.61 cm-1、1041.09 cm-1(−SO3).
2.2 Methods
(1) Interfacial tension measurements
The oil/water interfacial tension (IFT) was measured by using a Texas-500C
spinning drop tensionmeter in accordance with the following equation. The
volumetric ratio of water to oil is about 200 in the spinning drop tensiometer. When
measured values of IFT remained unchanged for half an hour, samples were assumed
to be equilibrated. The measurement of the interfacial tension was performed at
50.0℃±0.5℃, and all of the measurements were performed for no less than twice.
  3.42694  107

w  o
2D3
L / D  4

Where γ is the oil/water interfacial tension (mN/m); ρw and ρo are the densities of
the water and oil phases (g/cm3), respectively; w is the rotational speed (rpm); D and
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L are the width and length of the oil droplet (mm), respectively.
(2) Surface tension measurements
A surface tensiometer whose model is JYW-200B (Chengde Dahua Instrument Co.
Ltd., accuracy ±0.01 mN/m) was used to measure surface tension measurement with
the ring method. A thermostat cell holder controlled the temperature. The surface
tension was gained with a single-measurement method, and all of the measurements
were performed for no less than three times.
(3) Electrical conductivity measurements
The electrical conductivities of the solutions were carried out on a low-frequency
conductivity analyzer (model DDS-307, Shanghai Precision & Scientific Instrument
Co., Ltd., accuracy of ±1%). CMC of ionic micelle aggregates would be obtained by
measuring the electrical conductivity. The turning point in the chart of specific
conductivity versus concentration indicates the CMC.
(4) Dynamic light scattering (DLS)
A Zetasizer Nano ZS (Malvern) was used to perform the DLS measurement, and
the hydrodynamic radius of micelles which formed in aqueous solution depend on the
measurement. The DLS measurement was conducted at 25.0 ± 0.1 °C. A solid-state
He−Ne laser (22 mW) was used to obtain the incident beam, and the scattering angle
and the light wavelength are 90° and 632.8 nm, respectively. 1.5 mL of the sample
solution was dropped to a small square container, and DLS data were collected from
the mean values of the three measurements.
3. Results and Discussion
3.1 Interfacial Tension
Interfacial tension is an important parameter of surfactant for enhanced oil recovery.
Lower interfacial tension value means better performance of the surfactant in
enhanced oil recovery. The effect of enhanced oil recovery would be considerable
once the interfacial tension of biomass surfactant solution and crude oil declines to an
ultra-low level (＜10-2 mN·m-1). The interfacial tensions of Luliang crude oil (the
density is 0.860 g/cm3, the viscosity is 9.2 mPa·s at 50℃) and bine water (the salinity
is 10019.34 mg/l, the density is 1.013 g/cm3; the composition: Ca2+ 218.36 mg/l,
-
2-
2-
Mg2+9.74 mg/L, Na++K+ 3623.75 mg/l, HCO3 395.98 mg/l, CO3 44.1 mg/l, SO4
5.99 mg/l, Cl- 5765.52 mg/l) with different concentrations of biomass surfactant at
50℃ were shown in Figure 1. With the increase of concentrations, the minimum
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value of interfacial tension between oil and solutions of biomass surfactant with
different concentrations declined gradually (Figure 1). When the concentration of
DNPSS surfactant is 0.4% (wt), the minimum value of (IFTmin) could be 0.0040
mN·m-1. In oilfield applications, it is beneficial to make a lower usage of surfactants,
and having ultra-low interfacial tension is one of the paramount aims. At the
concentration of 0.3% (wt) NDPSS surfactant, the IFT was 0.0062 mN·m-1, which
also reaches up to an ultra-low level. It is common in petroleum exploitation to inject
water into reservoirs to displace oil as well as to maintain the reservoir pressure as the
natural pressure of the reservoir declines over the course of production. Typically,
about 65% of the hydrocarbons remain unproduced after natural drive and water
flooding [24]. The key reason of low oil rate of hydrocarbon is high interfacial tension
between oil and water, which leads to big flow resistance in porous media of reservoir
formation. According to the Laplace formula, the flow resistance was remarkably
reduced by lowing IFT between oil and water, therefore, the purpose of enhanced oil
recovery can be realized.22
Figure 1 The IFTs between Luliang crude oil and different concentration NDPSS solutions at 50℃
What is interesting is that once the concentration value of the biomass surfactant
fell far below that of the single surfactant in the work before, it would be better to
obtain the reduction of IFT. It is because of the synergism between the surfactant
analogues. Comparing to single-chain counterparts, mixture-chain surfactants have
excellent interfacial/surface performance due to the strengthened ability of molecular
self-assembly. Based on the theory of surface chemistry, several surfactants were
mixed frequently, aiming at reducing the dosage of surfactants as well as obtain lower
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surface/ interfacial tensions. Under such a condition, the final product NDPSS
surfactant was also a mixture derived from waste cooking oil exhibiting great
synergism as a naturally surfactant compound system [25-27]
.
3.2 Surface Properties and Micellization
Surface tension measurement was conducted to study the surface properties of
NDPSS surfactant in aqueous solution. The surface tensions of solutions and
o
concentrations at 25 C are illustrated in Figure 2. Comparing dilute NDPSS
surfactant solution and pure water(72mN·m-1), the surface tension value decreases
sharply in dilute NDPSS surfactant solution , which indicates that NDPSS surfactant
molecules are adsorbed at air-water interface. Surface tension would decline gradually
while NDPSS surfactant concentration increases. Surface tension would stop
decreasing and keep a constant value when the concentration of NDPSS surfactant
reaches a critical value. It indicates that the air-water interface has been saturated with
NDPSS surfactant molecules.
As seen in Figure 2, the arrow shows an inflection point on the plot of NDPSS
surfactant concentration versus surface tension. It is critical micelle concentration
(CMC) as traditionally termed. The NDPSS surfactant molecules would form micelles
in aqueous solution while NDPSS surfactant concentration keeps rising. Under 25℃,
the CMC value of NDPSS surfactant in aqueous solution dropped to 0.0019 mol·L-1,
and the surface tension at CMC was 28.0 mN·m-1. The lower CMC value is, the better
surface activity is. Comparing with the CMC values of other surfactants, the CMC
values of NDPSS surfactant were three orders of magnitude below that of other
bio-based surfactants, and the max of surface excess concentration was up to nearly
two times of others’ [28], which also means NDPSS surfactant has better surface
activity.
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Figure 2. Surface tension versus concentration of NDPSS solution at 25°C
From Figure 2, surface tension can decline to 27.8 mN/m because NDPSS
surfactant could be adsorbed at the air-water interface. To demonstrate the surface
activity, the following equation proposed the effect of surface tension reduction
(Πcmc):
Πcmc = γ0 − γcmc
(2)
Wherein, γ0 is the surface tension of water; γcmc is the surface tension of biomass
surfactant solutions when the concentration is higher than CMC.
For the NDPSS surfactant molecules, the value of Πcmc can be calculated as 44.0
mN/m according to the equation (2), and it demonstrates the good ability of
decreasing surface tension of NDPSS surfactant. For other types of bio-based
surfactants, such as N-phenyl fatty amidopropyl-N, zwitterionic surfactants,
N-dimethylcarboxylbetaine (PFAPMB), and N-fatty acyl amino acid surfactant
(SFAAA), their γcmc of surfactant aqueous solutions are 28.4, and 28.0 mN/m，
respectively [29, 30]. Comparing with the ability to decrease surface tension of
bio-based surfactants, their surface activities are similar.
As mentioned above, in Figure 2, the decrease of surface tension is because NDPSS
surfactant is adsorbed at air-water interface. Thus the adsorption behavior is studied.
Two parameters，the maximum surface excess concentration Γmax and the minimum
area Amin are introduced to demonstrate the adsorption phenomenon of NDPSS
surfactant, they occupied each surfactant molecule in the air-water interface, and the
two parameters can be calculated as follows [31]
:
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1
dγ
Γmax  
(
)
(3)
T
nRT d ln c
Wherein, n indicates the amount of solute species; the concentration of solute
species at the interface changes with surfactant concentration c; R indicates gas
constant; T represents absolute temperature; γ represents surface tension; and dγ/d(lnc)
indicates slope of surface tension γ versus lnc dependence when the concentration
approximates CMC.
For NDPSS surfactant of aqueous solution, when n is taken as 2, Amin can be
calculated according to the following equation (4):
1
Amin

(1023)
(4)
NAmax
Wherein, NA represents Avogadro number.
As seen in Table1, the value of Γmax is 3.38 μmol/m2 and Amin is 49.1 Å2 for the
adsorption phenomenon of bio-based surfactant NDPSS occurs on the air-water
interface at 25oC. Table 1 also clearly presents the comparison among the relevant
adsorption parameters.
Table 1. Surface Properties of NDPSS and other surfactant in Aqueous Solution(25℃)
surfactant
NDPSS
PFAPMB
SDS
cmc
γcmc(mN/m)
28.0
Πcmc(mN/m)
44.0
Γmax(μmol/m2)
3.38
Amin(Å2)
49.1
1.9 mmol/L
0.734 mg/L
8.2 mmol/L
28.4
43.6
2.66
62.0
32.5
39.5
3.16
53.0
PFAPMB, the other bio-based surfactant, its Amin value is 62.0 Å2 [30]. By
comparison, in NDPSS molecules, the value of Amin is lower, and the lower Amin
makes Γmax value a little higher, which implies NDPSS molecules pack more tightly at
air-water interface. This higher packing density may be on account of the structure of
NDPSS as well as the characteristics of molecular. Comparing with conventional
sodium dodecyl sulfate (SDS) surfactant, NDPSS molecules also have a smaller Amin
and a little larger Γmax, which introduces in a better surface activity compared with
SDS.
In order to further investigate the micelles which are formed of bio-based surfactant
NDPSS, DLS measurement was performed, and the hydrodynamic radius of the
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micelles formed in aqueous solution would depend on the result of the DLS
measurement. Figure 3 shows the result of DLS measurement when NDPSS
surfactant concentration is around 2 mM (slightly larger than its CMC). As seen in
Figure 3, the scattering peak is quite sharp; it demonstrates the micelles formation as
well as the uniform micelles’ radius. The average value of hydrodynamic radius is
around 9 nm.
Figure 3. Size distribution of NDPSS micelles in aqueous solution (2mmol, 25℃)
3.3 Thermodynamic Parameters of Micelle Formation
In general, temperature plays an important role in the self-assembly phenomenon of
surfactant in aqueous solution. We also employed electrical conductivity
measurements to study the micellar aggregation behavior of NDPSS in aqueous
solution. Figure 4a presents the curve of surface tensions vs NDPSS concentrations
under different temperatures. Table 2 shows the CMC values under the temperature of
25-45℃, which can be obtained quite easily.
(4a)
(4b)
Figure 4a. The conductivity versus NDPSS concentration. Figure 4b. The cmc values of NDPSS
micelles at different temperature
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Table 2 CMC and Degrees of counterion dissociation at different temperature
25
30
35
40
45
t/℃
CMC
1.80
0.675
1.87
0.679
2.00
0.682
2.15
0.686
2.38
0.690
（mmol·L-1）
α
Figure 4a shows the variations of specific electrical conductance which is a
function of NDPSS concentration under different temperatures. It can be surveyed
that the curves fit into two straight lines with different slopes for each temperature.
The break in conductivity versus concentration plot roots in the micellizaiton of
amphiphilic compounds [32]; in the break point, the concentration is equivalent to the
CMC. At 25℃, the CMC value is 0.0018 mol/L, which is estimated with the electrical
conductivity plot illustrated in Figure 4a, and this value is close to the CMC values
obtained from surface tension measurements (0.0019 mol/L at 25 ℃). The minor
discrepancy is mainly attributed to the fact that the CMC usually rest in the
determination method.
As seen in Figure 4a, the slopes of linear region below CMC are larger than that
above CMC. This is due to the counterion bound in the surface of micellar aggregates.
Viewed from another perspective, the loss of ionic charges is effective since a set
number of counterions are circumscribed to the micellar surface. The degree of
counterion dissociation α approximates the mean value of counterions/surfactant ion
which dissociates from the micelle, and the parameter can be calculated according to
the ratio which is between the slopes of curves below and above the CMC. The values
of α calculated for this bio-based surfactant NDPSS micelles at different temperature
are shown in Table 2. The value of α increases with the increase of the temperature,
probably caused by strong Brownian motion with fast ions movement. Figure 4b
presents the relationship of temperature and the CMC values. It can be seen that the
values of CMC increase as temperature increases due to weak hydrophobic interaction
of alkane chains [33], and this plot conforms to a second-order polynomial; it can
accord well with other surfactants in aqueous solution.
In terms of the thermodynamic parameters of the micelles generated by NDPSS in
0
aqueous solution, according to micellization’s pseudophase model，the value of ΔGm ,
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standard Gibbs free energy in micelle formation can be obtained using the equation
below [34]
:
0
ΔGm =（2-α）RT lnXcmc
(5)
Here, R represents gas constant; T represents absolute temperature; Xcmc represents
0
CMC in molar fraction, and it can be transmuted from CMC. The values of ΔGm in
different temperatures can be calculated according to equation (5), which is shown in
0
Table 3. It can be seen that the values of ΔGm nearly keep stable as temperature
increases, which implies that the formation process of micelles are spontaneous.
0
Besides, based on ΔGm , standard Gibbs free energy of adsorption (ΔGads0) could also
be obtained according to equation (6) [35]. In NDPSS molecules,
oC approximates -46.95 kJ/mol.
ΔGads0 value at 25
0
ΔGads0= ΔGm - Πcmc/ Γmax (6)
0
The standard enthalpy of micellar formationΔHm , another thermodynamic
parameter, can also depend on the Gibbs-Helmholtz equation below:
(Gm0 /T)
(1/T)
Hm0  [
]
(7)
0
According to equation (7), function 1/T plots the values of (ΔGm /T) , and Figure 5a
presents the curve. The curve in Figure 5a conforms to a second-order polynomial.
0
ΔHm values at different temperatures depend on the slope of tangential lines, which
0
0
are shown in Table 3. According to the values of ΔGm and ΔHm , ΔSm0 , micelle
formation’s standard entropy, can be calculated using equation (8); the results are
listed in Table 3.
0
0
0
ΔSm =( ΔHm - ΔGm )/T (8)
Figure 5b presents the relationship between temperatures (T) and thermodynamic
0
0
0
0
parameters (ΔGm , ΔHm , and −TΔSm ). ΔHm indicates the contributions of enthalpy
0
change and −TΔSm represents the enthalpy change to standard Gibbs free energy of
micelle formation. As seen in the plots, the Gibbs free energy hardly changes as
temperature increases, whereas the decline of the enthalpy variation and the increase
0
of the entropy variation are obvious. Comparing their effectiveness to ΔGm , the two
curves interests when the temperature is around 303K, which demonstrates entropy
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variation has a significant effect on determining ΔGm0 below the temperature of 303K,
and the micelle formation of NDPSS in aqueous solution is mainly entropy-driven.
However, the transform of enthalpy plays a significant role int determining ΔGm0 over
the temperature of 303K, and the micelle formation of NDPSS in aqueous solution is
mainly enthalpy-driven [36-38]. Therefore, the micelle formation is entropy and
enthalpy co-driven at 25-45oC. In that case, the arrangement of surfactant molecule on
the interface was more compact. Therefore, the surface tension of the solution was
lower. It is preferred to form micelles and the micelles would be much more stable.
The solubilization for oil is enhanced, thus this is helpful to increase the sweep
efficiency of the remaining oil from reservoir.
Table 3 Thermodynamic parameters of NDPSS micelles formed in aqueous solution
0
0
0
T(K) CMC(mMol/L)
△Gm (kJ·mol-1)
△Hm0 (kJ·mol-1)
-T△Sm (kJ·mol-1)
△Sm (J·mol-1·K-1)
298
303
308
313
318
1.80
1.87
2.00
2.15
2.38
-33.93
-34.27
-34.53
-34.74
-34.84
-10.97
-15.92
-20.71
-25.35
-29.84
-22.97
-18.35
-13.82
-9.39
77.06
60.57
44.88
30.01
15.72
-5.00
(5a)
(5b)
0
0
Figure 5a. The plot of ΔGm /T and T. Figure 5b. The plots of thermodynamic parameters (ΔGm ,
0
0
ΔHm , and ΔSm ) and T
In terms of the change of entropy and enthalpy in aqueous solution, some linear
relationships exist and they are usually named as entropy-enthalpy compensation
[39-41]. It is valuable to study the relationship of enthalpy and entropy transformation
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for micelle formation of NDPSS in aqueous solution. Entropy-enthalpy compensation
is usually consisted of two parts: the desolvation part because of the dehydration of
hydrophobic chain and the chemical part because of the aggregation of surfactant tails
0
0
to generate micelles. Enthalpy change (ΔHm )’s dependence to entropy (ΔSm ) is
0
0
presented in Figure 6a. This figure illustrates that the plot of ΔHm versus ΔSm has a
good linear relationship. The compensation of entropy amdenthalpy can be described
with the form below:
0
0
ΔHm =( ΔHmA + Tc ΔSm ) （9）
Wherein, Tc represents the compensation temperature as well as a measure of
desolvation part; ΔHmA is the enthalpy which belongs to chemical part.
According to the fitting of straight line, in NDPSS micelles formation, ΔHmA value
0
is −34.61 kJ/mol , Tc value is 307.7 K, and ΔSmA value is 112.5 J·mol-1·K-1(ΔHm =0).
This compensation temperature resembles the surfactant reported with the same
A
A
structures [42]. The parameters of ΔHm and ΔSm represent the stability of micelles.
The lower the value of ΔHmA is , the higher the value of ΔSmA is, and the more stable
the micelles are. Therefore, the NDPSS micelles are relatively stable.
As another thermodynamic parameter, as well as the heat capacity of micellization,
ΔCp,m0 could be obtained using the following equation (10) [43]
:
0
ΔCp,m0=T(∂ΔSm /∂T) (10)
Figure 6b presents the curve of micellization entropy which as a function of
temperature, and it can be seen that the plot accords with a good linear relationship.
The value of ΔCpm0 approximates -3.06 kJ·mol-1·K-1, which is to the same as the slope
of fitting line. The negative value of ΔCpm0 suggests that the hydration shell is missing
in the process of micellization because of the organized water molecules at the
surroundings of the hydrophobic chain of surfactant.
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(6a)
(6b)
Figure 6a. The relationship of enthalpy-entropy compensation. Figure 6b. ΔSm0 versus
temperature for NDPSS in aqueous solution
4. Conclusions
In conclusion, we studied the surface/interfacial properties of the bio-based surfactant
NDPSS. NDPSS exhibits excellent interfacial active, and the IFTs between Luliang
crude oil and NDPSS water solutions could reach up to an ultralow level, which
shows great potential application as an oil displacement agent in enhanced oil
recovery. NDPSS also has a quite low CMC value, which indicates an excellent
surface activity. The micelle formation is spontaneous, thermodynamically stable, and
is entropy and enthalpy co-driven at 25 to 45oC. Through this research work, we
expect to broaden its great potential application area in enhanced oil recovery as a
substitute of petroleum-based surfactants.
Acknowledgements
This work was supported by Beijing Natural Science Foundation (3154040),
Fundamental Research Funds for the Central Universities (2-9-2014-007), the
National Science Fund for Distinguished Young Scholars (51425406), and the Chang
Jiang Scholars Program (T2014152). The authors thank Dr. Yongpeng Sun and Yining
Wu editing of the English and his valuable suggestion on preparing this paper. The
authors also express their appreciation to technical reviewers for their constructive
comments.
Conflict of interest
The authors declare that they have no conflict of interest
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Reference
[1] Wilson, L. A.. Physico-chemical environment of petroleum reservoirs in relation
to oil recovery systems. Improved oil recovery by surfactant and polymer flooding,
Academic Press, 1997: 1-26.
[2] Zhao, F. L.. Oilfield Chemistry. China University of Petroleum Press, 2000:
104-109.
[3] Ye, Z. B.. Principles of enhanced oil recovery. Petroleum Industry Press, 2000:
103-110.
[4] Zhou, C. H., Zhang, Q., Liu, Y., et al. Effect of Fatty Acids on Interfacial
Tensions of Novel Sulfobetaines Solutions. Energy & Fuel, 2014, 28(2): 1020-1027.
[5] Qiao, W. H., Li, J., Zhu Y. Y., et al. Interfacial tension behavior of double
long-chain 1,3,5-triazine surfactants for enhanced oil recovery. Fuel, 2012, 96(1):
220-225.
[6] Zhang, Q. Q., Cai, B. X., Xu, W. J.. Novel zwitterionic surfactant derived from
castor oil and its performance evaluation for oil recovery. Colloids & Surfaces A,
2015, 483: 87-95.
[7] Banat, I. M.. Biosurfactants production and possible uses in microbial enhanced
oil recovery and oil pollution remediation: a review. Bioresource Technology, 1995,
51(1): 1-12.
[8] Xie, W. L.. Chemistry and technology of oils chemical products, Science Press,
1998: 60-78.
[9] Zhang, Y., Dube, M. A., McLean, D., Kates, M., 2003. Biodiesel production from
waste cooking oil: 1. Process design and technological assessment. Bioresource
Technology, 2003, 89(1): 1-16.
[10] Wang, L. T., Dong, X. Q., Jiang, H. X., et al. Preparation of a novel
carbon-based solid acid from cassava stillage residue and its use for the esterification
of free fatty acids in waste cooking oil. Bioresource Technology, 2014, 158(4):
392-395.
[11] Yao, Z. L., Min, E. Z., 2010. The hazard and utilization of waste edible oils. Gas
Industry, 2010, 5: 123-128.
[12] Liu, H. J., Ma, C. G. Miao, H. Q., et al. Research progress on sulfonated fatty
acid methyl ester. China Oils & Fats, 2011, 36(7): 54-57.
17

ACCEPTED MANUSCRIPT
[13] Wang, L. T., Dong, X. Q., Jiang, H. X., et al. Preparation of a novel
carbon-based solid acid from cassava stillage residue and its use for the esterification
of free fatty acids in waste cooking oil. Bioresource Technology, 2014, 158(4):
392-395.
[14] Du, Z. P., Wang, W. X., Tai, X. M.. Synthesis, property and application progress
of fatty acid methyl ester sulfonate. China Surfactant Detergent & Cosmetics, 2012, 4:
1-6.
[15] Li, L., Zhu, Y. C.. Research and application progress of fatty acid methyl ester
sulfonates. China Surfactant Detergent & Cosmetics, 2012, 4: 7-13.
[16] Zhang, L., Lan, H. B., Yun, Z.. Review on preparation and analytical methods of
fatty acid methyl ester sulfonate. China Surfactant Detergent & Cosmetics, 2010, 3:
210-213.
[17] Fan, W. L., Zhang, B., He, P., 2008. Study on the performance of fatty acid
methyl ester sulfonate in detergent. Applied Chemical Industry, 2008, 7: 830-833.
[18] Xu, M. X.. Production and application of fatty methyl ester’s derivatives,
Chemical Industry, 2012, 7: 30-32.
[19] Qiao, W. H., Cui, Y. C., Zhu Y. Y., et al., 2012. Dynamic interfacial tension
behaviors between Guerbet betaine surfactants solution and Daqing crude oil. Fuel,
2012, 102: 746-750.
[20] Okitsu, K., Sadanaga, Y., Takenaka, N., Maeda, Y., Bandow, H.. A two-step
continuous ultrasound assisted production of biodiesel fuel from waste cooking oils: a
practical and economical approach to produce high quality biodiesel fuel. Bioresource
Technology, 2010, 101(14): 5394-5401.
[21] Srilatha, K., Devi, B. P., Lingaiah, N., et al. Biodiesel production from used
cooking oil by two-step heterogeneous catalyzed process. Bioresource Technology,
2012, 119(7): 306-311.
[22] Zhao, G. X.; Zhu, B. X, 2003. Principles of surfactant action. China Light
Industry Press: Beijing, 2003: 274.
[23] Dai, C. L., Fu, Y., You, Q., et al. Bio-based sulfonate surfactant and its synthetic
method. CN103805155A, 2014.
[24] Green, D., Whillhite, G.. Enhanced Oil Recovery SPE Textbook Series.
Richardson, TX, 1998.
[25] Sreenu, M., Rao, B. V., Prasad, R. B. N., et al. Synthesis, surface and biological
properties of sodium N-acyl isoleucines. European Journal of Lipid Science &
18

ACCEPTED MANUSCRIPT
Technology , 2014, 116(2): 193-206.
[26] Rosen, M. J., Wang, H., Shen, P., Zhu, Y.. Ultralow interfacial tension for
enhanced oil recovery at very low surfactant concentrations. Langmuir, 2005, 21(9):
3749-3756.
[27] Biswal, N. R., Paria, S.. Interfacial and wetting behavior of natural-synthetic
mixed surfactant systems. RSC Advances. 2014, 4(18): 9182-9188.
[28] Blesic, M., Lopes, A., Melo, E., et al. On the self-aggregation and fluorescence
quenching aptitude of surfactant ionic liquids. Journal of Physical Chemistry B, 2008,
112(29): 8645-8650.
[29] Wu, M. H., Wan, L. Z., Zhang Y. Q.. A novel sodium N-fatty acyl amino acid
surfactant using silkworm pupae as stock material. Scientific Reports, 2014, 4(4):
4428.
[30] Zhang, Q. Q., Cai, B. X., Xu, W. J., et al. The rebirth of waste cooking oil to
novel bio-based surfactants. Scientific Reports, 2015, 5: 09971.
[31] Shanks, P. C., Franses, E. I.. Estimation of micellization parameters of aqueous
sodium dodecyl sulfate from conductivity data. Journal of Physical Chemistry, 1992,
96(4): 1794-1805.
[32] Wang, J. J., Wang, H. Y., Zhang, S. L.. Conductivities, volumes, fluorescence,
and aggregation behavior of ionic liquids [C4mim][BF4] and [Cnmim] Br (n=4, 6, 8,
10, 12) in aqueous solutions. Journal of Physical Chemistry B, 2007, 111(22):
6181-6188.
[33] Zhao, G. X.. Physical chemistry of surfactants. Peking University Press, 1984:
36-60.
[34] Wadekar, M. N., Boekhoven, J., Jager, W. F., et al. Micellization behavior of
aromatic moiety bearing hybrid fluorocarbon sulfonate surfactants. Langmuir, 2012,
28(7): 3397-3402.
[35] Chen, L. J., Lin, S. Y., Huang, C. C., et al., 1998. Temperature dependence of
critical micelle concentration of polyoxyethylenated non-ionic surfactants. Colloids.
& Surfaces A, 198, 135(1-3): 175-181.
[36] Wu, J., Li, N., Zheng, L., et al. Aggregation behavior of polyoxyethylene (20)
sorbitan monolaurate (Tween 20) in imidazolium based ionic liquids. Langmuir 2008,
24(17): 9314-9322.
[37] Dong, B., Gao, Y. A., Su, Y., et al. Self-aggregation behavior of fluorescent
carbazole-tailed imidazolium ionic liquids in aqueous solutions. Journal of Physical
19

ACCEPTED MANUSCRIPT
Chemistry B, 2009, 114(114): 340-348.
[38] Singh, H. N., Saleem, S. M., Singh, R. P., Birdi, K. S.. Micelle formation of ionic
surfactants in polar nonaqueous solvents. Journal of Physical Chemistry, 1980, 84(17):
2191-2194.
[39] Bedö, Z., Berecz, E., Lakatos, I.. Enthalpy-entropy compensation of
micellization of ethoxylated nonyl-phenols. Colloid Polymer Science, 1992, 270(8):
799-805.
[40] Chen, L. J., Lin, S. Y., Huang, C. C.. Effect of hydrophobic chain length of
surfactants on enthalpy-entropy compensation of micellization. Journal Physical
Chemistry B, 1998, 102(22): 4350-4356.
[41] Wu, W. X., Lian, H. X., Ding, W., et al. Thermodynamics for micellization of
anionic-nonionic gemini surfactants. Petrochemical Technology, 2013, 42(1): 39-46.
[42] González-Pérez, A., Ruso, J. M., Romero, M. J., et al. Application of
thermodynamic models to study micellar properties of sodium perfluoroalkyl
carboxylates in aqueous solutions. Chemical Physics, 2005, 313(1-3): 245-259.
[43] Li, N., Zhang, S., Zheng, L., Wu, J., Li, X., Yu, L., 2008. Aggregation behavior
of a fluorinated surfactant in 1-butyl-3-methylimidazolium ionic liquids. Journal
Physical Chemistry B, 2008, 112(112): 12453-12460.
20

ACCEPTED MANUSCRIPT
Graphical Abstract
Investigation on Interfacial/Surface Properties of Bio-based Surfactant
N-Aliphatic Amide-N,N-Diethoxypropylsulfonate Sodium as An Oil
Displacement Agent Regenerated from Waste Cooking Oil
Yan Zhang1,2, Qing You1*, Yang Fu2, Mingwei Zhao2, Hongfu Fan1, Yifei Liu2, Caili
Dai2*
Interfacial/Surface Properties of NDPSS
Graphical abstract
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Highlights
 A bio-based surfactant regenerated from waste cooking oil was synthesized
 The interfacial tensions can reach up to an ultralow level (<10-2 mN·m-1)
 The thermodynamic parameters of micellization were systematically investigated

This bio-based surfactant exhibits great potential oilfield application in EOR
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