Physical Stability Study of Liquid Surfactant Membrane
Hadria Ferdenache1,2*, Ouahiba Bechiri3, M.E. Hocine Benhamza1, M.E.
Hadi Samar3
1Laboratory
of Industrial Analysis and Materiel Engineering, Department of Process Engineering,
Faculty of Engineering, 8 Mai 1945 Guelma University, PO Box 401, Guelma, 24000,
Algeria.
2Research Center
in Industrial Technologies, CRTI, P.O. Box 64, Cheraga, 16014 Algiers, Algeria.
3Laboratory
of Environmental Engineering, Department of Process Engineering, Faculty of Engineering,
Badji Mokhtar Annaba University, PO Box 12, Annaba, 23000, Algeria.
*Corresponding Author E-mail: hadria.ferdenache@gmail.com
ABSTRACT:
In
this study, the stability of Liquid Surfactant Membrane (LSM) is investigated for
use in the extraction of toxic dyes. The LSM emulsion is prepared using Span80 as
a surfactant, tridodecylamine (TDA) as transporter and sulfuric acid as internal phase. Various parameters,
i.e. surfactant, transporter and internal phase concentrations, stirring and emulsification
speeds, membrane phase to internal phase volume and treatment ratios, emulsification
time as well as diluent type, are all examined in relation to emulsion stability.
Stability tests are performed using the tracer method, as well as rheological and
particle size analyses. Resultant optimal parameters using tracer method are: surfactant
concentration: 10% (w/w); transporter concentration: 1% (w/w), internal phase concentration:
1N, stirring speed: 200rpm, emulsification speed: 20000rpm; volume ratio of organic
phase to internal phase: 1/1, treatment ratio: 1/10, emulsification time: 5min;
and diluent type is cyclooctane. These findings are confirmed by rheological and
particle size analysis.
KEYWORDS: Emulsified Liquid
Membrane, Stability, Tracer method, Rheological property, Granulometric characterizations.
INTRODUCTION:
An emulsion is a combination of two immiscible liquids
blended under the effect of agitation or the addition of active ingredients. There
are several types of emulsion: simple (Oil in Water O/W), inverse (Water in oil
W/O) and multiple (W/O/W or O/W/O). Multiple emulsions are those in which micro-globules
of water dispersed in an aqueous medium are encapsulated in drops of oil. Multiple
emulsions W/O/W (Water in Oil in Water) are particularly promising in diverse applications1-3.
They are likely to be the subject of many industrial applications,
especially in the extraction and separation processes. The separation technique
covers many studies in different fields such as hydrometallurgy, process engineering4-6,
inorganic chemistry7,8, analytical chemistry9,10, physiology11,
biotechnology and biomedical engineering12-16.
Fig.
1. Liquid Surfactant Membrane structure
Among
the emulsions used in separation technique we find the Liquid Surfactant Membrane
(LSM) which is a multiple emulsion system made up of three phases, (Fig.1). These
are: the feed phase (containing one or more solutes to be treated and purified);
the membrane (usually composed of transporter, surfactant and diluent) and the internal
phase (that acts as reservoir of the solute extracted from the feed phase).
The
purpose of this study is to produce a stable liquid surfactant membrane for use
in the extraction of toxic dyes17-19. Thus, before proceeding with the
extraction process, a preliminary study of the stability of the emulsion is essential.
This is performed by using different methods specifically tracer method, rheological
and particle size analysis20-24
The
emulsion considered in this research work, is a Liquid Surfactant Membrane (LSM)
consisting of a surfactant (Span80), a transporter (tridodecylamine (TDA)) and an
internal phase (sulfuric acid). This emulsion is intended to be used in extracting
an organic pollutant, i.e. a toxic dye present in wastewater.
Optimal
parameters for a stable emulsion are therefore studied, namely: surfactant, transporter
and internal phase concentrations, type of diluent, stirring and emulsification
speeds, volume ratio of membrane phase to internal phase (O/A), treatment ratio
(Vemul/Vext) and emulsification time.
The
novelty of the present emulsion stability study is the use, in addition to the usual
tracing method, of a rheological and particle size analysis; which none of the previous
studies have investigated in the stability tests.
MATERIALS
AND METHODS:
Materials:
The
transporter (Tridodicylamine: TDA) and the emulsifier (a non-ionic surfactant type
Ester: the mono-Oleate of Sorbitane Span80) are purchased from "Sigma Aldrich ". The analytically pure sulfuric acid used in the
preparation of the aqueous internal phase is purchased from "Biochem". The various
diluents tested in this research work, i.e. heptane, hexane, cyclohexane, kerosene,
white spirit, octane and cyclooctane are procured from"Reidel-de Haёn,
Fluka and Sigma Aldrich".
Emulsion
preparation:
The
organic membrane phase is prepared by dissolving the transporter (TDA) and the surfactant
(Span80) in a diluent under a gently magnetic mixture for 5 minutes. While the internal
aqueous solution, is made by dissolving an appropriate quantity of sulfuric acid
(H2SO4) in distilled water. The water in oil emulsion (W/O)
is performed by blending the organic membrane phase with the internal phase (H2SO4),
by introducing it slowly into a beaker with intensive mixing (using a Wise Tis HG-15D
Homogenizer). Thus, the emulsion obtained is a homogeneous and stable milky white
solution.
Stability
emulsion analysis using a tracer method:
The
emulsion stability study is firstly achieved by a tracer method. Leakage of the
internal phase (sulfuric acid) H+ ion reduces the pH of the external
phase (distilled water); which can be easily detected by a pH-meter. This indicates a rupture
of the W/O emulsion and thus the emulsion breakage percentage 
can
be calculated using equation 1:
Ɛr = Vs/Vint × 100 (1)
Where:
Vs
is the volume of internal phase leaked into the external phase by splitting.
Vint
is the initial volume of internal aqueous phase.
The volume 
is
related to the pH by the following equation:
(2)
Where:
and 
are the pH external phase before contact and after contact
respectively,
[H+]t is the H+ ions concentration in the external
aqueous phase at a moment (t),
Vex is the external phase volume before contact.
The
prepared W/O emulsion is then dispersed into an external aqueous solution (distilled
water) with a known pH, the mixing is performed using a propeller agitator (type
RW20 Kjank & Kunkel). Finally, pH variations of the external phase are
tracked by a pH meter each two (2) minutes.
Stability
emulsion analysis using Rheological method:
Rheological
measurements are performed using a CVO Bohlin rheometer. Cone-plate geometry
(40 mm of diameter, 4° of angle) is selected; various tests are performed over a
shear rate ranging from 0.1 s−1 to 100 s−1 constant
temperature of 25°C.
Stability
emulsion analysis using Particle size method:
The
emulsions droplet size distribution and diameters are measured using a Mastersizer
2000 LASER diffraction instrument equipped with Hydro MU (Malvern Instruments).
Throughout measurements, a sufficient emulsion quantity is spread in the dispersion
unit until the correct range of optical system obscuration is reached. And the refractive
indices are chosen according to the selected emulsion.
RESULTS
AND DISCUSSION:
The
major problem associated with Liquid Surfactant Membrane (LSM) is its stability;
this latter is essentially affected by emulsion components, quantity, type as well
as operating conditions. Therefore, emulsion stability is investigated in relation
to its constituents and operating conditions.
Tracer
method stability analysis results:
Effect
of surfactant concentration:
Results
of surfactant concentration effect on the emulsion stability behaviour, (Fig.2 (a)),
show that emulsion stability increases with the increase of surfactant concentration.
Though, for lower surfactant concentrations emulsion rupture occurs, this is due
certainly to the insufficient surfactant amount required for surrounding all internal
aqueous phase. Increasing surfactant quantity is leading to a higher emulsion viscosity,
thus making the extraction kinetic more difficult25-27. As a result,
the amount of surfactant in the membrane phase must be at its optimum value to stabilize
the emulsion. Therefore, a value equals 10% (w/w) of surfactant concentration is
selected in all experiments.
Effect
of transporter concentration:
Taking into account the selected surfactant concentration
value, the transporter (TDA) concentration is varied from 0.5% to 3% (w/w). As a
result, the increasing of transporter quantity diminishes the emulsion stability
as shown in the (Fig.2 (b)). Since, a greater TDA quantity in the membrane increases
the viscosity and therefore leading to the formation of larger globules. On the
other hand, intensifying carrier concentrations also promotes the permeation swelling
which dilutes the aqueous receiving phase and thus decreases the efficiency of the
process28. Hence, optimum transporter concentration value is found to
be of about 1% (w/w).
Effect
of internal phase concentration:
The
effect of internal phase concentration is investigated using optimum values found
previously, i.e. a surfactant concentration of (10%) and a transporter concentration
of 1%. Thus, for H2SO4 internal phase concentrations varying
from 0.2N to 2N, the figure 2(c) shows the effect results of these variations on
the emulsion stability. Emulsion stability (indicating by rupture rate) increases
when H2SO4 concentration rises up to a value of 1N, however
beyond this value the emulsion stability decreases. This is certainly due to the
reaction of H2SO4 with surfactant, that involves a reduction
in the properties of the latter and thus destabilizing the emulsion. For feeblest
rupture rate, the given internal phase concentration equals 1N (optimum value).
Effect
of the diluent type:
The
emulsion stability is also examined for various solvents: heptane, hexane, cyclohexane,
octane, cyclooctane, white spirit and kerosene. Experimental results conducted under
previously found optimum conditions (Fig.2 (d)), show that cyclooctane diluent provides
a better emulsion stability because of its lower rate rupture.
Fig.
2. (a) Effect of surfactant concentration, (b) Effect of transporter concentration,
(c) Effect of internal phase concentration H2SO4, (d) Effect
of type diluents on membrane stability.
Effect
of stirring and emulsification speeds:
Study
of stirring and emulsification speeds effects on the emulsion stability is performed
under optimized parameters conditions. The results are shown in the figure 3.
At
lower agitation speeds (100rpm and 150rpm) (Fig.3 (a)), values of rupture rate are
extremely low. In contrast, at higher speeds (> 200rpm) the rupture rates become
more important. However, at higher agitation, there is formation of droplets which
increase the interfacial surface between external phase and emulsion globules; thereby
accelerating the mass transfer and thus increasing the extraction process29.
Consequently, it is very important to choose an appropriate agitation speed to preserve
emulsion stability together with better extraction; therefore, for the present study
a value of 200 rpm is selected.
Fig.
3. Effect of speed on membrane stability: (a) Effect of stirring speeds, (b) Effect
of emulsification speeds
Emulsification
speed effects on the emulsion stability, Figure 3 (b), show an emulsion rupture
diminution when emulsification speed increases. A good dispersion gives efficient
emulsification, because the internal phase breaks in the membrane phase. Moreover,
drops become small and decrease coalescence, thereby creating a larger permeation
surface area which is beneficial to a good emulsion stability. A speed of 20000
rpm is thus considered as optimal value.
Effect of volume ratio (membrane phase to internal phase
O/A) and treatment ratio (Vemul/Vext):
Volume
ratio effects (i.e. membrane phase to internal phase O/A) ranging from 1/2 to 2/1
on emulsion stability are presented in (Fig.4 (a)). The curve lines display an increasing
in O/A ratio implying a reduction in the rupture rate; consequently, emulsion stability
increases with increasing of O/A ratio. The rise in the O/A ratio increases the
internal drops size distribution and thus augments the emulsion viscosity. The increase
in droplet diameters decreases the interfacial contact area between emulsion and
continuous phase, thereby reducing the extraction efficiency30. Therefore,
the membrane phase viscosity has a large effect on the mass transfer rate. From
these results, and in order to obtain a good emulsion dispersion, internal phase
to membrane phase volume ratio of 1/1 is selected as the best ratio.
Fig.
4. (a) Effect of volume ratio of membrane phase to internal phase O/A, (b) Effect
of treatment ratio (Vemul/Vext) on membrane stability
Fig.
5. Effect of emulsification time on the membrane stability
Treatment
ratio (Vemul/Vext) effects on emulsion stability experiments
are conducted using all optimized parameters identified till now and ratios are
varied from1/5 to 1/20.
Effects
of these variations on emulsion stability displayed in (Fig.4(b)), indicate that
increasing in treatment ratio amplifies the emulsion rupture. Indeed, when increasing
emulsion ratio, the swelling phenomenon becomes significant, rapid and accompanied
by greater coalescence; thus causing the emulsion rupture. From these results the
optimum emulsion treatment ratio selected is 1/10.
Effect
of emulsification time:
Experiments are conducted at optimum conditions and with
variable emulsification time, from 3 to 10 min. Effects of emulsification time on
emulsion stability shown in figure 5, indicate that emulsification time of 5 min
improves the emulsion stability; though further increases reduce emulsion stability.
For an emulsification time less than 5min, high rupture occurs, this is due to the
presence of larger size droplets leading to coalescence. In contrast, for a prolonged
emulsification time rupture increased; this is due to high internal shearing engendering
a very high number of small droplets by volume unit, which contributes to their
diffusion into external phase. Hence, an emulsification time of 5 min is selected.
Rheological
analysis results:
As
seen previously, several parameters influence the emulsion stability and thus affecting
the emulsion rheological and granulometric properties i.e. droplets size and their
distributions. In this research study part, parameters that have a significant effect
on the liquid membrane emulsion stability are considered i.e. surfactant concentration,
emulsification time and rate, O/A ratio and the type of diluent.
A rheological
analysis is performed and viscosity with shear rate variations results are illustrated
in (Fig.6).
Viscosity
versus shear rate variations for different Span80 surfactant concentrations in figure
6 (a), display an augmentation in emulsion viscosity when surfactant concentration
rises. However, the viscosity decreases with the increase of the applied shear rate
indicating that the emulsion has a shear thinning rheological behaviour 31-34.
As regards to emulsification time effect, (Fig.6 (b)) presents almost the same curve
trend; though an emulsification time of 10 min gives highest viscosities.
Figure
6 (c) illustrates viscosity vs. shear rate variations for different emulsification
speed. This illustrates that viscosities decrease when the shear rate diminishes;
and viscosity disparities related to the rate of emulsification are insignificant
probably due to the droplet diameters which have reached their smallest diameter.
Results of emulsion viscosity vs shear rate for different volume ratio (O/A) in
the figure 6 (d), show an increase in viscosity for augmented O/A ratio, this is
owing to organic phase enhancement. In addition, a decrease of emulsion viscosities
is observed when shear rate increases indicating a shear thinning rheological behaviour.
In figure 6 (e) viscosity plots related to diluents type show that cyclooctane solvent
presents the highest viscosity.
All
emulsion rheological curves characterize a non-Newtonian behaviour for which the
viscosity decreases with increasing of the shear rate.
Granulometric
analysis results:
When
formulating emulsions, the results required arise from a compromise between stability
and appropriate application properties. The required application property in the
present study is a higher mass transfer rate between internal and external phases.
Thus, a particle size characterization is carried out to study droplet diameter
distribution and therefore examining emulsion stability35-37, as illustrated
in (Fig.7).
Emulsion
particle size distribution related to surfactant Span80 concentration (Fig.7 (a)),
shows that the main droplet population has a diameter of around 100 µm. Two other
populations of greater diameter droplets are also present; though with a volume
proportion less than 2%. Regarding the emulsification time, the droplet size distribution
(Fig. 7 (b)) shows a single mode distribution and where the highest volume is perceived
at a time of 5 minutes. As regards to emulsification speeds, the particle size distribution
(Fig.7 (c)), shows a narrow droplet distribution of a diameter around 100 µm and
this at 8000 rpm and 20000 rpm. However, for an emulsification speed of 15000 rpm
a wider distribution of a diameter size around 200 µm is perceived.
In
(Fig.7 (d)), emulsion particle size distribution at different O/A ratios, shows
a single mode distribution of diameters around 100 µm for O/A = 1 and 2. However,
for O/A equal to 0.5, a wider distribution with a population of droplets of larger
diameter is observed. Finally, concerning diameter size distribution for different
diluent types, Fig.7 (e) illustrates that cyclooctane and kerosene have two particle
size populations; on the other side heptane and cyclohexane diluents have three
populations. Thus, this granulometric characterization shows a mono-disperse distribution
of diameter droplets around 100 µm indicating its stability and that LSM is a macro
emulsion.
CONCLUSION:
The
aim of this study is to develop a stable Liquid Surfactant Membrane (LSM) for use
in the extraction of toxic dyes. The LSM emulsion is prepared using Span80 as a
surfactant, tridodecylamine (TDA) as transporter and sulfuric acid as internal phase. Various parameters
are investigated in order to obtain a stable emulsion. The resulting optimal parameters
using a tracer method are: Surfactant concentration 10% (w/w); transporter concentration:
1% (w/w), internal phase concentration: 1N, stirring speed: 200 rpm, emulsification
speed: 20000 rpm; volume ratio of organic phase to internal phase: 1/1, treatment
ratio: 1/10, emulsification time: 5min; and diluent type: cyclooctane.
The
emulsion stability is also investigated by means of rheological and granulometric
analysis and the obtained results confirm the emulsion stability when using optimal
parameters. Measurements are corroborated by a high emulsion viscosity with a mono-disperse
droplets distribution of a diameter around 100 µm indicating its stability. The
emulsion has non-Newtonian and shear thinning behaviour, since viscosity decreased
with shear rate.
ACKNOWLEDGEMENTS:
This
work was supported by Algerian Higher Ministry of Education (General Directorate
of Scientific Research and Technological Development (DGRSDT)) and the Laboratory
of Industrial Analysis and Materiel engineering (LAIGM) of the University 8 Mai
1945 Guelma, Algeria.
CONFLICT
OF INTEREST:
The
authors declare no conflict of interest.
REFERENCES:
1. S. Sivapriya, P.A. Daisy et al. Multiple emulsions a comprehensive review. World Journal
of Pharmaceutical and Medical Research 2016; 2: 83-88.
2. Li, N.N.; Separation of let us hydrocarbons with liquid
membranes. USA Patent. 1968.
3. Sarika S. Lokhande. Recent Trends in Multiple Emulsion- A Comprehensive
Review. Asian J. Res. Pharm. Sci. 2019; 9(3):201-208. doi: 10.5958/2231-5659.2019.00032.8.
4.
P. S. Kulkarni, S. Mukhopadhyay and
S. K. Ghosh. Liquid Membrane Process for the selective Recovery of Uranium form
industrial Leash solutions. Ind. Eng. Chem. Res. 2009; 48:3118-3125.
5.
Ankit Srivastava, Ankush Bhagat et al.
Comparative study of arsenic (V) removal from aqueous solution using Aliquat-336
and 2-ethyl hexanol through emulsion liquid membrane. Journal of Water Process Engineering
2017; 16:64–68.
6.
Aziza Hachemaoui, Kamel Belhamel. Simultaneous
extraction and separation of cobalt and nickel from chloride solution through emulsion
liquid membrane using Cyanex 301 as extractant. International Journal of Mineral
Processing 2017; 161: 7-12.
7.
A. Kargari, T. Kaghazchi. Role of emulsifier
in the extraction of gold (III) ions from aqueous solutions using the emulsion liquid
membrane technique. Desalination 2004; 162: 237-247.
8. N. Othman, H. Mat, M. Goto. Separation of silver from photographic
wastes by emulsion liquid membrane system. J. Membr. Sci. 2006; 282: 171–177.
9.
O. Bechiri, M. E. Samar, M. Abbessi.
Extraction of a Dawson-type Mixed Heteropolyanion from Aqueous Solution by Liquid
Surfactant Membrane Using (NH4)2CO3 as Internal
Phase. J. Chem. Eng. Chem. Res. 2015; 12: 932-938.
10.
M. Matsumoto, T. Ohtake, et al. Extraction
rates of amino acids by an emulsion liquid membrane with tri-n-octylmethylammonium
chloride. Journal of Chemical Technology and Biotechnology 1998; 73: 237–242.
11.
J. Bernardino de la Serena,
J. Petrez Gil, et al. Direct observation of
the coexistence of two fluid phases in native pulmonary surfactant membranes at
physiological temperatures. The Journal of Biological Chemistry 2004; 27973: 40715–40722.
12.
S. Chaouchi, O. Hamdaoui. Extraction
of endocrine disrupting compound propylparaben from water by emulsion liquid membrane
using trioctylphosphine oxide as carrier. Journal of Industrial and Engineering
Chemistry 2015; 22: 296 –305.
13.
Y. Ki Hong, W. Hi Hongand D. Hoon Han.
Application of reactive extraction to recovery of carboxylic acids. Biotechnology
and Bioprocess Engineering 2001; 6: 386-394.
14.
A. Dâas, O. Hamdaoui. Extraction of
bisphenol from aqueous solutions by emulsion liquid membrane. Journal of Membrane
Science 2010; 348: 360–368.
15. Aidaa Maaz, Saleh Trefi, Mohammad Haroun, Wassim Abdelwahed. Preparation
of Gatifloxacin Microparticles by Double Emulsification w/o/w method for Ocular
Drug Delivery: Influence of Preparation Parameters. Research J. Pharm. and Tech.
2017; 10(5):
1277-1288. DOI: 10.5958/0974-360X.2017.
00227.X.
16. Sarika S. Lokhande. Microemulsions as Promising Delivery Systems:
A Review. Asian J. Pharm. Res. 2019; 9(2): 90-96. doi: 10.5958/2231-5691.2019.00015.7.
17. Sarita Yadav, D.K. Tyagi, O.P. Yadav. An overview of Effluent
Treatment for the Removal of Pollutant Dyes. Asian J. Research Chem. 5(1): January2012;
Page01-07.
18. Bayader F. Abbas, Wessal M. Khamis Al-Jubori, Ahmed M. Abdullah,
HananKd. Sha`aban, Mustafa Taha Mohammed. Environmental Pollution with the Heavy
Metal Compound. Research J. Pharm. and
Tech 2018; 11(9): 4035-4041. doi: 10.5958/0974-360X.2018.00743.6.
19.
Rummi Devi Saini. Synthetic Textile Dyes:
Constitution, Dying process and Environmental Impacts. Asian J. Research Chem. 2018;
11(1): 206-214.doi:10.5958/0974-4150.2018.00040.8.
20.
O. Bechiri, F. Ismail,
M. Abbessi, M. E. H. Samar. Stability
of the emulsion (W/O): Application to the extraction of a Dawson type heteropolyanion
complex in aqueous solution. Journal of Hazardous Materials 2008; 152: 895–902.
21. RPS Rathore, RK Nema. Formulation and Estimation of Rheological
Parameters of Topical Gels of Ketoprofen. Research J. Pharma. Dosage Forms and Tech.
2009; 1(3):226-228.
22. M. Kishore Babu, K.V. Subhashini, N. Aruna, T.E.G.K. Murthy. Rheological
Studies of Gum Karaya (Sterculia urens) and Gum Kondagogu (Cochlospermum gossypium)):
Tree Gums of India. Research J. Pharm. and Tech. 4(5): May 2011; Page 775-778.
23. Sumit Mishra, Gurdeep Singh. A Study on Particle Size Distribution
Profile of Coal Combustion Residues from Thermal Power Plants of India. Asian J.
Research Chem. 3(2): April- June 2010; Page 386-388.
24.
Vikram Kumar Sahu, Amit Mishra, Nitin
Sharma, Pratap Kumar Sahu, Shubhini A. Saraf . Physical Rheological and Cell Viability
Study of Some Selected Plant Polysaccharides. Research J. Pharm. and Tech. 2017;
10(1): 227-232. doi: 10.5958/0974-360X.2017.00048.8.
25.
Zahra Seifollahi, Ahmad Rahbar-Kelishami.
Diclofenac extraction from aqueous solution
by an emulsion liquid membrane: Parameter study and optimization using the response
surface methodology. Journal of Molecular Liquids 2017. 231: 1-10.
26.
A. Dâas, O. Hamdaoui. Removal of non-steroidal
anti-inflammatory drugs ibuprofen and ketoprofen from water by emulsion liquid membrane.
Environ. Sci. Pollut. Res. 2014; 21: 2154–2164.
27.
S. Chaouchi, O. Hamdaoui. Acetaminophen
extraction by emulsion liquid membrane using Aliquat 336 as extractant. Separation
and Purification Technology 2014; 129: 32–40.
28. Y.H. Wan, X.D. Wang, X.J. Zhang. Treatment of high concentration
phenolic waste water by liquid membrane with N503 as mobile carrier. J. Membr. Sci.
1997; 135: 263–270.
29. V. Eyupoglu, R.A. Kumbasar. Extraction of Ni (II) fromspent
Cr–Ni electroplating bath Solutions using LIX 63 and 2BDA as carriers by emulsion
liquid membrane technique. J. Ind. Eng. Chem. 2015; 21: 303-310.
30.
E.A. Fouad, H.-J. Bart. Emulsion liquid
membrane extraction of zinc by a hollow-fiber contactor. Journal of Membrane Science
2008; 307: 156–168.
31. Irina Masalova, Reza Foudazi, A. Ya. Malkin. The rheology
of highly concentrated emulsions stabilized with different surfactants. Colloids and Surfaces A: Physicochem. Eng.
Aspects 2011; 375: 76–86.
32.
Svetlana R. Derkach. Rheology of emulsions.
Advances in Colloid and Interface Science 2009; 151: 1–23.
33.
V. Muguet, M. Seiller, G. Barratt, O.
Ozer, J.P. Marty, J.L. Grossiord. Formulation of shear rate sensitive multiple emulsions.
Journal of Controlled Release 2001; 70: 37–49.
34.
S. Boufas, M. E. H. Benhamza, B. Ben
Seghir, H. Ferdenache. Synthesis and Characterization of Chitosan/Carrageenan/Hydroxyethyl
cellulose blended gels. Asian J. Research Chem. 2020; 13(3): 13(3):209-215.
35.
M. Chabni, H. Bougherra, H.
Lounici, et al. Evaluation of the Physical
Stability of Zinc Oxide Suspensions Containing Sodium Poly-(acrylate) and Sodium
Dodecylsulfate. Journal of Dispersion Science and Technology 2011; 32: 1786–1798.
36.
S. Desplanques, F. Renou et
al. Impact of chemical composition of xanthan
and acacia gums on the emulsification and stability of oil-in-water emulsions. Food
Hydrocolloids 2012; 27: 401-410.
37.
A. Nesterenko, A. Drelich et
al. Influence of a mixed particle/surfactant
emulsifier system on water-in-oil emulsion stability. Colloids and Surfaces A: Physicochem.
Eng. Aspects 2014; 457: 49–57.