AOT Solutions Research Articles

Dioctyl sulfosuccinate sodium salt (AOT) as a corrosion inhibitor for AZ31 Mg alloy: Effects of integration with layered double hydroxide (LDH)

Surfactants are known for their corrosion inhibition effect for metallic substrates like magnesium (Mg) alloys. Among these surfactants, dioctyl sulfosuccinate sodium salt, also known as AOT, is noteworthy. The present study investigates the corrosion inhibition of AOT on AZ31 Mg alloy using electrochemical impedance spectroscopy (EIS). In addition, surface characterization is conducted through scanning electron microscopy (SEM), energy-dispersive X-ray spectroscopy (EDS), X-ray diffraction (XRD), and X-ray photoelectron spectroscopy (XPS). Moreover, the interaction energy between AOT and the substrate is determined using Density Functional Theory (DFT) calculations. It is observed that AOT is effective for corrosion inhibition by being adsorbed on the surface of Mg alloy. The DFT calculations yield −5.25 eV value as interaction energy confirming the EIS results and the ability of AOT to prevent corrosion. The other part of this study involves incorporating AOT in layered double hydroxide (LDH) and demonstrating the enhanced corrosion resistance of the conversion layer facilitated by the surfactant. The existence of LDH structure after immersion in AOT solution was confirmed by SEM images and XRD test. The LDH structure was enhanced by increasing LDH inner layer thickness (from 11.8 ± 0.2 µm in LDH to 16.3 ± 0.3 µm) due to the addition of AOT, resulting in improved corrosion resistance of the substrate. These findings have significant implications for utilizing AOT as a corrosion inhibitor, particularly in the context of organic coatings, where AOT can serve as a vital link between the substrate and the organic coating.

Characterization of Copper nanoparticles obtained in AOT reverse micelles using flavonoids as a reducing agent

Purpose of the study. To characterize copper nanoparticles obtained in reverse micelles of sodium bis-(2-ethylhexyl)-sulfosuccinate (AOT) using flavonoids: quercetin and rutin in comparison with traditional reducing agents - sodium borohydride and hydrazine. Methods. Chemical synthesis of copper nanoparticles, spectrophotometry to determine the maximum of the plasmon absorption band of copper nanoparticles, electron transmission microscopy. Results. The reduction of copper ions using flavonoids – quercetin and rutin – confirmed the possibility of obtaining copper nanoparticles in the Cu+2/AOT/isooctane system (AOT is sodium bis-(2-ethylhexyl)-sulfosuccinate, an anionic surfactant that forms the micelle shell). During the formation of nanoparticles, “plasmonic” absorption bands were observed in the electronic spectra in the region of 400-440 nm. In the case of the traditional reducing agent, sodium borohydride, absorption is observed in the region of (439 ± 3) nm, which can also be attributed to the “plasmonic band” of copper nanoparticles, but its intensity is very low, which indicates the formation of a small amount of copper nanoparticles. Using transmission electron microscopy. The average size of copper nanoparticles was determined: 7.1, 8.2 and 18.5 nm in the case of quercetin, rutin and hydrazine, respectively. From the histograms constructed from the results of electron transmission microscopy, it follows that the use of flavonoids as reducing agents makes it possible to reduce the average size of copper nanoparticles and narrow their size distribution. Conclusion. Copper nanoparticles obtained in a reverse micellar solution of AOT in iso-octane using the flavonoids quercetin and rutin as a reducing agent have an average size of 7-8 nm and a narrower size distribution compared to reduction with hydrazine.

Influence of dialkyl chains of sulfosuccinate sodium salt surfactant on interfacial tension between hydrophobic material and water

We investigated the interfacial tension between a hydrophobic solid and aqueous solutions of bis(2-ethylhexyl) sulfosuccinate sodium salt (AOT), its analogues with different hydrophobic chains, and sodium dodecyl sulfate (SDS). The hydrophobic solid surface was prepared through chemisorption by n-octadecanthiol on an Au film on glass slide. As the hydrophobic oil, triolein was used. It was shown that sulfosuccinate surfactants largely decreased the interfacial tension between the hydrophobic solid and the aqueous solutions compared to SDS. Furthermore, it was observed that a 20 mM AOT aqueous solution induced spontaneous detachment of a triolein droplet from the hydrophobic solid surface in water. This concentration of AOT solution for the detachment was consistent with that expected through the calculation of the spreading coefficient.

Effect of double chain anionic surfactant on the dynamic interfacial tensions of betaine solutions

To clarify the effect of the anionic surfactant with double alkyl chains on the interfacial tension (IFT) of betaine solutions, the IFT values of the sodium dialkyl sulfosuccinates (AOT) mixed with different betaines (alkyl sulphobetaine (ASB) and benzyl substituted alkyl sulphobetaine (BSB)) against n-alkanes and crude oil were detected by the spinning drop method. Additionally, molecular dynamics (MD) simulation was employed to verify the interaction mechanism between AOT and different betaine molecules. The results demonstrate that AOT molecules reach hydrophilic-lipophilic balance and form a relatively compacted interfacial film at the dodecane-water interface. Owing to the flexible double alkyl chains, AOT molecules possess a robust self-regulating ability at the oil–water interface. It is the self-regulating ability of AOT molecules and the electrostatic attraction between betaines and AOT molecules that achieve superior synergistic effects between AOT and betaine molecules with different molecular sizes. Besides, mixed adsorption and hydrophilic-lipophilic balance (HLB) reduce the IFT values of mixed systems containing AOT and different betaines effectively. The equilibrium IFT of the AOT-ASB system and the AOT-BSB system can be reduced to ultralow vales of 5.7 × 10−3 mN/m and 8.2 × 10−3 mN/m, respectively. At the crude oil–water interface, active components in crude oil compete with AOT molecules, which results in a significant increase in IFT values for AOT solution alone. Despite the different molecular sizes of ASB and BSB molecules, the flexible double alkyl chains of AOT molecules enable AOT to have synergistic effects with both ASB and BSB molecules at crude oil–water interface. Ultralow IFTs against crude oil can be obtained at optimized ratio of AOT to betaines, which is meaningful for the application of mixed solutions containing betaines and anionic surfactants in enhanced oil recovery.

Evidence for an L3 phase in ternary deep eutectics: composition-induced L3-to-Lα transition of AOT.

Pure and hydrated deep eutectic solvents (DES) are proposed to form self-assembled nanostructures within the fluid bulk, similar to the bicontinuous L3 phase common for ionic liquids (ILs). Labelled choline chloride : urea : water DES were measured using small-angle neutron scattering (SANS), showing no long-range nanostructure. However, solutions of the surfactant AOT in this DES yielded scattering consistent with the L3 "sponge" phase, which was fitted using the Teubner-Strey model. A disclike model gave local structural information, namely, a linear increase in radius versus solvent water content (w = molar ratio of DES : water), eventually forming large, turbid lamellar phases at 10w; an L3-to-Lα transition was observed. Simultaneous multi-contrast SANS fits show the surfactant headgroup region is dominated by interactions with poorly-soluble Na+ at low water contents, and numerically-superior [cholinium]+ as water content increases. The modified interfacial Gaussian curvature from cation : anion volume matching stabilizes the lamellar morphology, allowing the bilayer aggregation number to increase.

Influencing foam properties of aqueous bis(2-ethylhexyl)sulfosuccinate solutions by addition of polypropylene-glycol-modified and amino-modified silica nanoparticles

The effect of silica nanoparticle (SiO2NP) addition on the air-water interfacial rheology and foam properties was investigated in aqueous solutions of bis(2-ethylhexyl)sulfosuccinate (AOT), an anionic surfactant. Two types of SiO2NPs were prepared: polypropylene-glycol-modified SiO2NPs (PPG-SiO2NPs) and amino-modified SiO2NPs (NH2-SiO2NPs). The addition of SiO2NPs stabilized the foam in the aqueous AOT solution in all cases, but the effect on the air-water interfacial behavior differed depending on the SiO2NP type. Adsorption of NH2-SiO2NPs to the air-water interface improved the air-water interfacial dilational viscoelasticity (E), enhancing foam stability. Although PPG-SiO2NPs did not adsorb to the air-water interface, the movement of AOT molecules to the air-water interface was partially suppressed by hydrophobic interaction with PPG-SiO2NPs in the bulk aqueous solution. This event limited the decrease in E, thereby stabilizing the foam.

Influence of Adsorption Characteristics of Surfactants Sodium Dodecyl Sulfate and Aerosol–OT on Dynamic Process of Water-Based Lubrication

Surfactant solutions are widely used in industry, and their steady-state lubrication properties have been comprehensively explored, while the “dynamic process” between steady states attracts much less attention. In this study, the lubrication behaviors of sodium dodecyl sulfate (SDS) and sodium bis (2–ethylhexyl) sulfosuccinate (Aerosol–OT, AOT) solutions were comparatively and extensively discussed. Experimental results showed that the duration of the dynamic process of AOT solution lubrication was significantly shorter than that of SDS. The essence of the dynamic process was revealed from the aspects of the running-in of solid surfaces and the adsorption process of surfactant molecules. Unlike the general recognition that the friction force evolution mainly corresponds to the running-in of surfaces, this study indicated that the dynamic adsorption behavior of surfactant molecules mainly contributes to this process. Various experiments and analyses showed that the smaller steric hindrance and lower orientation speed of SDS molecules led to longer diffusion into the confined contact zone and a longer duration of friction force decrease. This work enhances our understanding of the dynamic friction process in water-based lubrication, which could also have important implications for oil-based lubrication and its industrial applications.

An Insight Into the Effect of Drug Betaine Hydrochloride on the Micelle Forming Tendency of Surfactant AOT

The present analysis employs an electrical conductometric measurements to monitor the effect of addition of drug Betaine hydrochloride (BH) on the double chain anionic surfactant sodium bis(2-ethylhexyl)sulfosuccinate (AOT). Different concentrations (0.10, 0.25, and 0.50) mmolkg-1 of drug Betaine hydrochloride have been added to the aqueous solution of surfactant AOT at three various temperatures (298.15, 308.15, and 318.15)K in order to examine the micellization properties of the surfactant AOT. The values of critical micelle concentration, and various thermodynamic quantities, which include Gibb’s free energy of micellization (ΔG0 m), enthalpy of micellization (ΔH0 m), and entropy of micellization (ΔS0 m), have been computed from the conductivity measurements. The interactions prevailing among the surfactant-drug system have been discussed in order to explore their applications in drug delivery systems.

Condition dependent self-aggregation behavior of aerosol-OT in mixed water-alcohol media: Physicochemical investigation

Amphiphiles aggregation in mixed aquo-organic solvent media has profound interest in the fields of chemistry, biology, pharmaceutics, and industry. Detailed fundamental understanding of the process in the bulk and at the interface is still remaining to be explored. In this report, the effect of two water miscible alkanols (ethanol (ET), and isopropanol (IP)) on the aggregation-behaviors of the surfactant sodium dioctylsulfosuccinate (Aerosol-OT or AOT) has been studied in a wide range of alcohol proportions (0 to 100 vol%) in water. Different physicochemical parameters like critical micelle concentration (CMC), counter-ion binding (β) and aggregation number (Nagg) of micelles, and the energetics of the AOT adsorption at the air/water interface, and its assembly formation in the bulk have been evaluated employing tensiometry and isothermal titration calorimetry (ITC) methods. The micelle forming region of AOT has been found to be 0–30 vol% for ET, and 0–20 vol% for IP. At [solvent] > 30 vol% the possibility of formation of “randomly arranged globular assembly” (RAGA) of the amphiphile [1] prevailed. Role of different solvent parameters have been attempted to explain the thermodynamics of the micellization process of AOT. SANS experiments have supported vesicle formation of concentrated solutions of AOT in 50 vol% ET or IP in water; with increasing alcohol vesicles transformed into micelles. DFT (density functional theory) calculations have been made for understanding the intermolecular interactions in AOT-H2O-ET or IP systems compared to their binary mixtures (AOT-H2O; AOT-ET; AOT-IP). NMR study has supported favorable interactions of the alkanols (ET and IP) with the head group of the AOT. Formation of micelles and reverse micelles by AOT in different composition of alcohols and pure alcohols reported by Michor and Berg [2] has been reasoned out to be incorrect.

Aqueous solutions of AOT as a dispersion medium for stabilization of SiO2 nanoparticles

SiO2 nanoparticles and surfactant sodium bis-(2-ethylhexyl) sulfosuccinate (AOT) are widely used in modern nanochemistry to obtain novel materials in various processes. However, only a few publications are devoted to investigation of the stabilization mechanisms of SiO2 dispersions in aqueous AOT solutions. In this work, the surface electrical properties of SiO2 nanoparticles and the nature of free charges in aqueous solutions were studied over a wide range of AOT concentrations (2.5∙10–6 ÷ 2.5∙10–2 M). The absolute value of ζ-potential of the particles increased from –42 to –58 mV, while the hydrodynamic radius remained constant and equal to ca. 40 nm. Calculations within the Derjaguin–Landau–Verwey–Overbeek (DLVO) theory revealed that stability of hydrosols is caused by the electrostatic component of disjoining pressure. Due to the repulsion of similarly charged nanoparticles and glass substrate, the hydrosols formed coffee rings during evaporation of sessile droplets. The results obtained make it possible to control surface properties of the particles, thus opening the possibility to use SiO2-AOT hydrosols for the formation of various 2D materials and substrates in photonics, catalysis and biosensorics.

Low-Voltage Polarization in AOT Solution to Enhance the Corrosion Resistance of Nitinol

In this work, the corrosion behavior of bare nitinol (NiTi) alloy in Ringer's solution containing different concentrations of sodium bis(2-ethylhexyl) sulfosuccinate (AOT) was first studied in order to determine whether the surfactant acts as a corrosion inhibitor. Results of potentiostatic and potentiodynamic experiments allowed concluding that AOT is a pitting corrosion inhibitor for NiTi. In a second stage of this research work, NiTi was treated under potentiostatic control (2.00 V) for 1 h in 0.10 M AOT solutions of pH 8.4 and 12. Static and rotating electrodes were used. The influence exerted by this treatment on the passive behavior of the alloy was studied in Ringer's solution using different electrochemical and surface analysis techniques. The best anticorrosion performance was obtained using a rotating electrode and AOT solution of pH 8.4. The thin oxide layer grown potentiostatically consists of TiO2, while no Ni was found in the outermost layer. The presence of this oxide layer allows reducing the amount of Ni and Ti released at open circuit potential conditions and at very positive potentials where pitting corrosion of the bare alloy occurs.

Foam Destabilization Effect of Sodium Bis(2-ethylhexyl)sulfosuccinate on Sodium Alkylsulfate Aqueous Solutions Based on Its Fast Surface Tension Gradient Relaxation

Abstract This study investigated the relationship between the air–water interfacial dilational viscoelasticity and foam properties in mixed anionic surfactant aqueous solutions of sodium bis(2-ethylhexyl)sulfosuccinate (AOT), sodium n-dodecylsulfate (C12AS), sodium n-tetradecylsulfate (C14AS), and sodium n-hexadecylsulfate (C16AS). The surfactants used here differ only in hydrophobic chains. The air–water interfacial viscoelasticity of AOT aqueous solutions mixed with C12AS or C14AS was similar to that of AOT single aqueous solutions at the same constituent concentration of AOT. On the other hand, the air–water interfacial viscoelasticity of mixed aqueous solutions of AOT and C16AS was intermediate between the respective single aqueous solutions. The foam properties of these mixed aqueous solutions were evaluated by a modified Ross–Miles method and it was shown that foam stability is correlated with the maximum value of viscoelastic modulus in mixed aqueous solutions of AOT and AS.

Varying the Surface Charges of Gold Nanoparticles in Span 80, AOT, and Span 80 + AOT Micellar Systems in n-Decane

Gold nanoparticles with different diameters of the metal core are obtained by reducing HAuCl4 with hydrazine in reverse emulsions stabilized by Span 80 (9.4 ± 0.4 nm), AOT (6.1 ± 0.2 nm), and an equimolar Span 80 + AOT mixture (10.0 ± 0.2 nm). After synthesis, only the nanoparticles in the AOT solutions (ζ potential 16.8 ± 0.9 mV) display electrophoretic mobility. Nanoparticles in the form of a small-volume liquid phase concentrate are also separated from excess reagents and by-products by concentration (non-aqueous electrophoresis, or centrifugation) and diluted with micellar solutions (Span 80, AOT, and Span 80 + AOT mixture) or pure solvents (n-decane and chloroform). As a result, 24 organosols are obtained, including ones with positive (11), negative (8), and uncharged (5) nanoparticles. Of particular potential interest are organosols that have the same macrostructure in terms of surfactants, but with oppositely charged gold nanoparticles (7 pairs of organosols are obtained).

Structure and conductivity of AOT solutions in n-hexadecane-chloroform mixtures.

The structure and conductivity of AOT (sodium bis(2-ethylhexyl) sulfosuccinate) solutions (2.5 × 10-4 -2.5 × 10-1 M) in n-hexadecane-chloroform mixture at the chloroform concentration from 50 to 100 vol% were studied. The diffusion ordered spectroscopy NMR study revealed that in the indicated range, the observed hydrodynamic diameter of micelles depends only on the AOT concentration and does not depend on the chloroform content. Molar fractions of free AOT molecules and those aggregated into micelles were calculated using the Lindman's law: at concentrations above 2.5 × 10-1 М, the solutions contain mostly the micelles, whereas at concentrations below 2.5 × 10-4 M, the solutions contain AOT molecules. The transition region contains both the AOT molecules and the micelles. Conductivity measurements were used to determine free charge carriers in the bulk of solutions and their contributions to conductivity.

Effects of Polypropylene Glycol at Very Low Concentrations on Rheological Properties at the Air-Water Interface and Foam Stability of Sodium Bis(2-ethylhexyl)sulfosuccinate Aqueous Solutions.

The present study investigates the effects of very low concentrations of polypropylene glycol (PPG) on the rheological properties of sodium bis(2-ethylhexyl)sulfosuccinate (AOT) aqueous solutions at the surface for the precise control of foam properties. Langmuir trough experiments and Brewster angle microscopy (BAM) of the AOT monolayer on the surfaces of PPG aqueous solutions indicated that a very low concentration of PPG increased the number of AOT molecules at the surface. Viscoelastic behaviors at the surface and surface tension isotherms in mixed aqueous solutions of AOT and PPG revealed that AOT interacted with PPG in the surface and bulk phase. A modified Ross-Miles method was performed to assess the foam stabilities of AOT aqueous solutions with and without PPG. The stabilization of foam by PPG was attributed to the rheological properties of AOT aqueous solutions at the surface.

Synthesis and Electrophoretic Concentration of Ag–Cu Nanoparticles of the Core–Shell Type in an AOT Microemulsion in n-Decane

Stable organosols of silver and copper bimetallic nanoparticles were obtained in sodium bis(2-ethylhexyl) sulfosuccinate (AOT) reverse micelles in the emulsion and microemulsion variants and characterized by physicochemical methods. The adsorption layer of nanoparticles in AOT solutions in n-decane was found to have a complex multilayer structure; an increase in the mole fraction of copper led to an increase in the hydrodynamic diameter of nanoparticles from 14 to 23 nm and a decrease in the electrokinetic potential from 18 to 7 mV. The surface charge of nanoparticles can be increased by diluting the sols with chloroform, and electrophoretic concentration can be performed with concentration factors of 30–50 depending on the composition. Based on the XRD data for solid composites in AOT, it was concluded that the structure of nanoparticles is most likely of the “core–shell” type with a silver metal core and a surface layer of X-ray amorphous copper.

Investigation of Surfactant AOT Mediated Charging of PS Particles Dispersed in Aqueous Solutions

Nano/submicron particles can be activated by surfactants and aggregate at the air-water interface to generate and stabilize foams. Such systems have been applied extensively in the food, medicine, and cosmetic industries. Studying particle charging behavior in a particle/surfactant/water system is a fundamental way to understand the activation of the particle surface. This paper presents an investigation of the charging behavior of polystyrene (PS) particles dispersed in aqueous solutions of the surfactant sodium di-2-ethylhexylsulfosuccinate (AOT). The results showed that zeta potential of PS was related to the AOT concentration with two different concentration regions. Below the critical micelle concentration (CMC), the charging of PS particles was effected by AOT ions; while above the CMC, it came from both AOT ions and AOT micelles. This behavior was different from that observed for PS in aqueous salt solutions. Additionally, the particle concentration and size were found to affect the zeta potential differently in the two AOT concentration regions. By analyzing these results, the charging mechanism of the PS/AOT/water system was revealed to be preferential adsorption. In summary, the study disclosed the internal connection between the PS charging in aqueous AOT solution and the activation of PS particles, as well as their influence to foam formation and stability.

\u03b1-Tocopherol/AOT/alkane/water system

In this paper the calorimetric studies on α-tocopherol/AOT/alkane/water systems are presented. Structural representations of surfactant AOT (a) and α-tocopherol (b) are shown below. α-Tocopherol (antioxidant) is a form of vitamin E that is preferentially absorbed and accumulated in humans. AOT is an anionic type of surfactant. Its molecule contains two non-polar hydrocarbon tails connected to the polar head. The paper contains new experimental data of heat of mixing (Q) for heterogeneous system α-tocopherol/AOT/n-alkane with and without water measured at 309.2 K. The heat of mixing for AOT (sodium bis (2-ethylhexyl) sulfosuccinate) and α-tocopherol solutions in n-alkane (heptane, decane, hexadecane) as the function of surfactant concentration and parameter R given as the water to surfactant molar ratio R = [H2O]/[AOT] was measured. It can be seen that the Q values grow significantly with temperature increase which indicates on entropic origin of this process. The significant influence of surfactant concentration on Q values was noticed. Unexpectedly, the water presence in the reverse micelles did not have any noticeable influence on the heat of mixing values measured at 309.2 K. There was not noticed the significant hydrocarbon chain length influence on the thermal effect of mixing α-tocopherol and AOT solutions. The thermodynamic parameters: the binding constant (K) and the molar enthalpy of transition (ΔHtr0) of α-tocopherol between solvent and AOT reverse micelles, were calculated from the heat of mixing data as a function of surfactant concentration using the nonlinear regression method. The new calorimetric data measured at 309.2 K were compared to results obtained earlier at 298.2 K, as well as have been discussed in the context of the hydrocarbon chain length and water presence influence on α-tocopherol solubility in AOT reverse micelles. Generally in all investigated systems have been not found a significant influence of water concentration in AOT reverse micelles on α-tocopherol molecules distribution between organic phase and micellar phases. The exothermic values of α-tocopherol molecules transition from organic to micellar phase indicate on spontaneous motion of α-tocopherol towards AOT aggregates. For the systems with n-heptane and n-decane as a solvent, the (ΔHtr0) values are between −51 and −52 kJ mol−1 whereas for n-hexadecane around −43 kJ mol−1. Such tendency can be explained through hydrocarbon chains orientation effect existing in hexadecane which probably is responsible for a α-tocopherol molecules freedom motion limitation. Moreover, the solubility of the α-tocopherol in AOT reverse micelles measured with calorimetric technique has been compared to the literature data obtained, respectively, with UV spectrophotometer for reverse micelles, and for phospholipids bilayer by other techniques. Finally, transferring of α-tocopherol from solvent to AOT reverse micelles, intermolecular interactions between α-tocopherol and AOT micelles were discussed, and a privileged place of α-tocopherol in the palisade layer of AOT reverse micelle has been deduced.

Morphology-controllable Cu2O supercrystals: Facile synthesis, facet etching mechanism and comparative photocatalytic H2 production

Monodisperse Cu2O-cubes, Cu2O-concave cubes and Cu2O-octapods supercrystals have been synthesized successfully using a self-assembly approach in the presence of dioctyl sulfosuccinate sodium salt (AOT) surfactant. Specifically, the supercrystals can be prepared by adding aqueous Cu(Ac)2 solution into butyl alcohol solution of AOT to first assemble nanoreactors and then perform hydrothermal reactions. The structures of the supercrystals can be tailored by simply varying the amount of Cu (Ac)2 with the same ratio of the Cu(Ac)2 to ascorbic acid. AOT surfactant was crucial to precisely control the supercrystal morphology. It was demonstrated that the ratio of growth rate along different planes varied by adjusting the amount of Cu(Ac)2 and the volume ratio of alcohol to water, thus Cu2O crystals with cubes, concave cubes, and octapods with the size of 1.2–2.2 μm were obtained. The morphology evolution from cubes, concave cubes to octapods was systematically studied and a facet etching mechanism is proposed. Hence, precise control of the amount of Cu(Ac)2 enables this facet etching, novel Cu2O with concave {100} facets can be fabricated. Photocatalysis investigation on the morphology-controlled Cu2O indicates that the Cu2O-octapods supercrystals showed the highest amount of H2 and the best cyclic-stability. This work reveals that morphology-control of supercrystals is important to the development of novel photocatalysis.

Micelle Formation of Aerosol-OT Surfactants in Sea Water Salinity

Gemini surfactants group recently showed importance in screening techniques for the evaluation and selection of chemicals for enhanced oil recovery. Aerosol-OT (sodium bis (2-ethylhexyl) sulfosuccinate, AOT) is a versatile anionic Gemini surfactant which is widely used in the chemical and biophysical research, which is also included in the category of sulfonated hydrocarbons and shows high potential in laboratory experiments. In this paper, the micellar behaviour of anionic AOT in presence of high sodium salt concentration was studied at different temperature from (25–105) $$\,^{\circ }$$ C. Surface tension techniques using duoy ring were applied for each surfactant concentration to find the critical micelle concentration (CMC) at each temperature. Several thermodynamic parameters were also reported as the standard Gibbs energies of micellization, $$\Delta G^{0}$$ ; the standard enthalpy change of micellization, $$\Delta H^{0}$$ ; and the standard entropies of micellization, $$\Delta S^{0}$$ , were calculated from the temperature effect on the CMC. Results showed that CMC values increased with temperature. The enthalpy of micellization was found to be negative in all cases, and it showed a strong dependence on temperature in the AOT solution in the presence of high concentration of NaCl system.