Energy Of Micellization Research Articles

Interaction of cationic surfactant cetyltrimethylammonium bromide (CTAB) with hydrophilic ionic liquid 1‑butyl‑3‑methylimidazolium chloride [C4mim][Cl] at different temperatures – Conductometric and FT-IR spectroscopic study

This paper delineates the effect of hydrophilic ionic liquid 1‑butyl‑3‑methylimidazolium chloride on micellar behavior of cationic surfactant cetyltrimethylammonium bromide (CTAB). Significant physicochemicalproperties like conductance, critical micelle concentration are detected to change as [C4mim][Cl] is added to aqueous CTAB. The conductivity data of surfactant CTAB in aqueous solutions of ionic liquid were experimentally determined in the temperature range from 298.15 to 308.15 K with the interval of 5 K. Obtained experimental data of conductivity have been utilized to deduce the critical micelle concentration (CMC). Using temperature dependence of CMC secured from conductivity measurements numerous thermodynamic parameters of micellization namely standard enthalpy of micellization (ΔHm0), standard free energy of micellization (ΔGm0), and standard entropy of micellization (ΔSm0) have been evaluated. FT-IR Spectra recorded for individual IL and some selected concentration to analyze the structural changes prevailed in the system. Results have been discussed in terms of effect of hydrophilic ionic liquid 1‑butyl‑3‑methylimidazolium chloride [C4mim][Cl] on the micellization process of the surfactant cetyltrimethylammonium bromide (CTAB).

Solubility Enhancement of Polycyclic Aromatic Hydrocarbons by an Eco-Friendly Ester-Linked Gemini Surfactant and its Mixtures with Conventional Surfactants

AbstractThe present study deals with the solubility enhancement of the two polycyclic aromatic hydrocarbons (PAHs) anthracene and pyrene in the aqueous micellar system of the cationic ester-containing cleavable gemini surfactant ethane-1,2-diyl-bis(N,N-dimethyl-N-tetradecylammoniumacetoxy) dichloride (14-E2-14 = C14H29(CH3)2N+(CH2COOCH2)2N+(CH3)2C14H29 · 2Cl−)), and its equimolar binary mixtures with some typical conventional cationic, anionic and non-ionic surfactants. The surface tension and conductivity measurements were used to evaluate the physicochemical parameters such as the critical micelle concentration (CMC), the interaction parameter (βm) and Gibbs excess free energy of micellization (ΔGexm) of the systems. The extent of solubilization of the micellar systems towards PAHs has been quantified in terms of molar solublization ratio (MSR), micellar/water partition coefficient (ln Km) and the standard Gibbs free energy of solubilization (ΔGs0). Above the CMC, all studied single as well as binary gemini-conventional surfactant systems show an increase in solubilization of the PAHs. For pure systems, the MSR value of Brij 58 was found to be significantly higher than that of the other amphiphiles. Amongst the mixed surfactant systems, the solubility enhancement of anthracene is found to be maximum in the 14-E2-14 + SDS/SDBS system whereas the system14-E2-14 + Brij 58 shows a higher solubility for pyrene.

Imidazolium‐Based Ionic Liquid as Modulator of Physicochemical Properties of Cationic, Anionic, Nonionic, and Gemini Surfactants

AbstractThe aggregation morphology of 2 cationic surfactants (cetyldimethylethanolammonium bromide and cetyldiethylethanolammonium bromide), an anionic surfactant (sodium dodecylbenzenesulfonate), a nonionic surfactant (Triton X‐100), and 2 gemini surfactants (16‐4‐16,2Br−[butanediyi‐1,4‐bis(dimethyldohexylammonium bromide)] and 16‐6‐16,2Br−[hexanediyi‐1,6‐bis(dimethyldohexylammonium bromide)]) in the presence of the ionic liquid (IL) 1‐ethyl‐3‐methylimidazoliumbromide [Emim][Br] is studied using various techniques such as surface tension, conductivity, and UV–visible and fluorescence spectroscopy. Increasing the concentration of [Emim][Br] results in a decrease in the critical micelle concentration (CMC) value of the surfactants. Various interfacial properties, namely the surface excess concentration (Гmax), minimum area per molecule at the air–water interface (Amin), and surface pressure at the CMC (πcmc), as well as the thermodynamic parameters such as free energy of the given air/water interface (), Gibbs free energy of micelle formation (), Gibbs free energy of micellization per alkyl tail (), Gibbs energy of transfer (), and standard free energy of adsorption () were also investigated. The aggregation number (Nagg) was determined by the fluorescence method. It was observed that Nagg decreased with increasing weight‐percent of the IL.

Aggregation behaviour of cationic (cetyltrimethylammonium bromide) and anionic (sodium dodecylsulphate) surfactants in aqueous solution of synthesized ionic liquid [1-pentyl-3-methylimidazolium bromide] -Conductivity and FT-IR spectroscopic studies

Current study includes the conductivity and spectroscopic study of the cationic surfactant cetyltrimethylammonium bromide (CTAB), and anionic surfactant sodium dodecylsulphate (SDS), in aqueous solutions of ionic liquid 1-pentyl-3-methylimidazolium bromide [C5mim][Br] at different temperatures T=(298.15, 308.15, 318.15) K. Obtained experimental data of conductivity have been utilize to determine the critical micellar concentration (CMC) i.e. concentration at which the self-assembly of amphiphilic molecules take place, also the effect of temperature on CMC have been studied. Critical micelle concentration has been utilized to calculate the thermodynamic parameters such as, standard enthalpy of micellization (ΔHm0), standard free energy of micellization (ΔGm0), and standard entropy of micellization (ΔSm0). Results obtained from thermodynamic parameters has been discussed in terms of structural changes occurred in the system. Work is mainly concerned with the influence of ionic liquid 1-pentyl-3-methylimidazolium bromide [C5mim][Br] on the micellization process of the cetyltrimethylammonium bromide (CTAB) and sodium dodecylsulphate (SDS) at below CMC, CMC and above CMC. Alterations produced in the structure of the mixtures (surfactants and aqueous solutions of ionic liquids) have been discussed by FT-IR Spectroscopic studies.

Investigations of interactions between surface active ionic liquid 1-butyl-3-methyl imidazolium dodecylbenzenesulfonate and cationic polyelectrolyte poly(diallyldimethylammonium chloride) in aqueous solution

In the present study, we have reported a comprehensive assessment of interactional behavior between the surface active ionic liquid (SAIL) 1-butyl-3-methylimidazolium dodecylbenzene sulfonate [C4mim][DBS] and cationic polyelectrolyte poly(diallyldimethylammonium chloride) [PDADMAC] solution in aqueous solution. Various techniques such as surface tension, isothermal titration calorimetry (ITC), conductivity, dynamic light scattering (DLS) and turbidity have been employed to get insight into interactions among [C4mim][DBS] and polyelectrolyte in the interfacial region. Then surface parameters such as surface excess concentration (Γcmc), surface pressure at interface (Πcmc), minimum area occupied by one molecule of SAIL at air-solvent interface (Αmin), adsorption efficiency (pc20) and surface tension at critical micelle concentration (cmc) (γcmc) have been calculated from tensiometric measurements. The values of cmc decrease with increase in concentration of polyelectrolyte indicating towards the predominance of electrostatic interactions except at intermediate concentration (0.01 g/L PDADMAC) for which hydrophobic interactions can be held responsible. The standard enthalpy of micellization (∆Hm°) has been obtained from ITC measurements. Further, thermodynamic parameters i.e. standard free energy of micellization (∆Gm°) and standard entropy of micellization (∆Sm°) have been evaluated from conductivity measurements. The size of complexes formed among [C4mim][DBS] and polyelectrolyte have been characterized using DLS and turbidity measurements. Overall, the electrostatic interactions play a major role among SAIL and polyelectrolyte which is generally expected from oppositely charged systems. The process of micellization has been found to be exothermic and spontaneous thermodynamically in presence of PDADMAC supported by gain in entropy.

Densities, refractive indices and conductivities of aqueous [Cnmim][Pro] solutions (n = 4, 8, 12); micellization and the capillary electrophoresis data at 298.15 K

The densities of aqueous solutions of amino acid ionic liquids (AAILs) based on 1-alkyl-3-methylimidazolium cations and L-prolinate anions [Cnmim][Pro] (n = 4, 8, 12) in the concentration range 0-97 wt % were measured at several constant temperatures in the range 293.15-318.15 ± 0.05 K. It has been found that in the range of high AAIL concentrations the dependence of the density values on the AAIL mole fraction for binary water + [Cnmim][Pro] solutions is nonlinear. The refractive indices of aqueous solutions of these AAILs in the concentration range 0-97 wt % and the electrical conductivities of aqueous [Cnmim][Pro] (n = 8, 12) solutions were measured at temperature 298.15K. Critical micelle concentrations (cmc) of AAILs, degree of counterion binding (β), standard Gibbs energy of micellization (ΔG°m) for them were estimated from the experimental data. The dependences of the cmc, β and ΔG°m, on the length of the alkyl chain of the cations were discussed. The synthesized AAILs [Cnmim][Pro] were examined as chiral selectors for the separation of D,L-tryptophan and D,L-tyrosine enantiomers using the ligand exchange capillary electrophoresis. The highest resolution factors Rs are observed in the case of [C4mim][Pro] used as a chiral ligand: Rs = 5.3 for D,L-tryptophan and Rs = 2.2 for D,L-tyrosine.

Effect of additives (TX-114) on micellization and microstructural phenomena of amphiphilic ibuprofen drug (sodium salt): Multi-technique approach

Interactions between anionic drug sodium salt of ibuprofen (IBU) and nonionic surfactant Triton X-114 (TX-114) micelles have been explored by means of surface tension, fluorometry and 1H NMR techniques in aqueous and in the occurrence of 250 mmol kg−1 urea (NH2CONH2). IBU is anti-inflammatory drug having analgesic as well as antipyretic property. The various mixed micelles, mixed monolayer as well as thermodynamic parameters like critical micelle concentration (cmc), interaction parameter in solution/interface (βm/βσ), maximum surface excess concentration (Γmax), Gibb's free energy of micellization (ΔGm), Gibb's free energy of adsorption (ΔGads), excess free energy of aggregation/interface (ΔGexm/ΔGexσ) etc. have been estimated as well as discussed. Due to the presence of urea cmc values of pure as well as mixed amphiphiles systems increases owing to enrichment in the surface electron density of the micelles or mixed micelles. The values of βm/βσ were found to be negative in solution/interface at all studied composition showing the attractive interaction between the constituent in both media (aqueous/250 mmol kg−1 urea). The negative values of ΔGm and ΔGads demonstrate that micelle formation, as well as adsorption at the air/water interfacial surface, is energetically supportive. Mixed interfacial surface are wealthy in TX-114, showing a stable as well as packed adsorbed mixed surfaces of a solution. The micelle aggregation numbers (Nagg) and various others related parameters were evaluated by means of fluorescence quenching method that indicate the contribution of TX-114 was always more than that of the drug (IBU). The interactions between the studied components were additionally studied by 1H NMR spectroscopic method which recommended that drug and surfactant interact via hydrophobic interaction in absence and occurrence of NH2CONH2.

Interactional behavior of surface active ionic liquid lauryl isoquinolinium bromide and anionic polyelectrolyte poly(4-styrenesulfonic acid-co-maleic acid) sodium salt in aqueous solution

In the present study, we have reported a detailed assessment of interactional behavior between the surface active ionic liquid (SAIL) lauryl isoquinolinium bromide ([C12iQuin][Br]) and anionic polyelectrolyte poly(4-styrenesulfonic acid-co-maleic acid) sodium salt (PSS-co-MA) in aqueous media. Various techniques such as surface tension, conductance, dynamic light scattering, and turbidity have been employed to get insight into interactions among [C12iQuin][Br] and polyelectrolyte in the interfacial region. Then, surface parameters such as surface excess concentration (Γcmc), surface pressure at interface (Πcmc), minimum area occupied by one molecule of SAIL at air–solvent interface (Αmin), adsorption efficiency (pC20), and surface tension at critical micelle concentration (cmc) (γcmc) have been calculated from tensiometric measurements. Further, thermodynamic parameters, i.e., standard enthalpy of micellization $$ \left(\Delta {H}_{\mathrm{m}}^{{}^{\circ}}\right) $$ , standard free energy of micellization ( $$ \Delta {G}_{\mathrm{m}}^{{}^{\circ}} $$ ), and standard entropy of micellization ( $$ \Delta {S}_{\mathrm{m}}^{{}^{\circ}} $$ ) have been evaluated. The size and shape of complexes formed among [C12iQuin][Br] and polyelectrolyte have been characterized using DLS and turbidity measurements.

Insights on Structuration of Peroxotungstic Acid in Aqueous Media

Recent studies on tungsten oxide preparation are mainly motivated by its applications in smart windows, energy harvesting and, recently, in cancer therapy. Peroxotungstic acid (PTA) is an important precursor to obtain tungsten oxide in an environmentally-friendly way, through the colloidal synthesis in aqueous media. Despite giving chemically pure products, PTA originates oxides with various morphologies depending on the experimental conditions, a subject open to discussion. PTA, in the presence of sodium dodecyl sulfate (SDS) as architecture-directing agent, was investigated in ethanol/water medium by small angle X-ray scattering (SAXS), fluorescence, surface tension and conductivity measurements; the morphology of tungsten oxide obtained from the precursor systems was also characterized by scanning electron microscopy (SEM). PTA/SDS/ethanol/water systems show a two-level organization in which small micelles are aggregated as fractal structures. There is an inverse correlation between gyration radius of the fractal structures of the PTA/SDS systems and particle size of the tungsten oxide films. The interaction of PTA with SDS is observed by reducing the Gibbs energy of micellization; also, it is evidenced that the supressive effect of PTA on pyrene emission is overrided in presence of SDS.

Micellar Properties of Surface Active Ionic Liquid Lauryl Isoquinolinium Bromide and Anionic Polyelectrolyte Poly(Acrylic Acid Sodium Salt) in Aqueous Solution

AbstractThe complex formation between anionic polyelectrolyte poly(acrylic acid sodium salt) [NaPAA] and surface active ionic liquid (SAIL) lauryl isoquinolinium bromide [C12iQuin][Br] in aqueous media has been investigated by surface tension, isothermal titration calorimetry (ITC), and conductance. The self‐assembled structures have been characterized using dynamic light scattering (DLS) and turbidity measurements. A range of surface parameters have been calculated from tensiometric measurements including critical micelle concentration (CMC), surface excess concentration (Γcmc), surface pressure at the interface (Πcmc), minimum area occupied at air–solvent interface (Amin), adsorption efficiency (pC20), and surface tension at the CMC (γcmc). The thermodynamic parameters, i.e., standard enthalpy of micellization , standard free energy of micellization (), and standard entropy of micellization () have also been evaluated. Four different stages of transitions, corresponding to the progressive formation of NaPAA–[C12iQuin][Br] complex (C1), critical aggregation concentration (CAC), critical saturation concentration (C3) and CMC have been observed owing to strong electrostatic and hydrophobic interactions. The results obtained from DLS and turbidity measurements show that size of the aggregates first decreases and then increases in the presence of polyelectrolyte. The binding isotherms obtained using isothermal titration calorimetry (ITC) show the concentration dependence as well as the highly cooperative nature of interactions corresponding to formation of polyelectrolyte–SAIL complexes.

Micellisation behavior on the dodecyltrimethylammonium bromide in the presence of Brij-35 in pure water by conductivity measurement

Conductivity measurement of dodecyltrimethylammonium bromide in the presence of Brij-35 in aqueous media at 289.15 K is performed. The result showed a sharp increase in conductivity with increase in the concentration of dodecyltrimethylammonium bromide in the presence of Brij-35. The graph of specific conductivity versus concentration is used in determining the critical micelle concentration (CMC). There is the decrease in CMC of dodecyltrimethylammonium bromide in the presence of Brij-35 in comparison with the CMC of dodecyltrimethyl ammonium bromide [DTAB]. Gibbs free energy of micellisation has also been evaluated. BIBECHANA 15 (2018) 85-89

Micellization of sodium dodecyl sulphate in presence and absence of alkali metal halides at different temperatures in water and methanol-water mixtures

The micellization of sodium dodecyl sulphate (SDS) in presence and absence of KCl, KBr, NaBr and NaCl in water and methanol-water mixtures containing 8, 16, 25 and 34wt% of methanol at 298.15 to 323.15K have been assessed from conductometric measurements. The concentrations of SDS were varied from ~0.001 to ~0.05molL−1 and salts concentration was 0.01molL−1. The critical micelle concentration (CMC) of SDS in presence and absence of salts in water as well as in methanol-water mixtures are found to increase with the increase in temperature and found to decrease with the addition of salts. The CMC of SDS in water and methanol-water mixtures in presence of studied salts is found in the order NaCl>NaBr>KCl>KBr.Thermodynamic properties of micellization such as the standard free energy of micellization, standard enthalpy of micellization, the standard entropy of micellization, the standard free energy of transfer and heat capacity of micellization of SDS in presence and absence of salts have been examined. The micellization of SDS with presence and absence of salts has been assessed in terms of different solvent parameters. The solvophobic parameters have been presented.

Effect of gemini surfactant additives on pour point depressant of crude oil

ABSTRACTEfficiencies of cationic gemini surfactant additives in improving the pour point depressant of crude oil were investigated. The length of alkyl chain is a major factor affecting the improvement of the pour point depression. The adsorption behavior of these gemini surfactants at air/solution and oil/solution interfaces were investigated by measuring the surface tension and interfacial tension as functions of concentration. It is found that there is a good relation between surface properties especially interfacial tension of the gemini surfactants and their efficiency in depressing the pour point. Also, the surface parameters and free energies of micellization and adsorption confirm the decreasing and improving of pour point depression. Crystallization study in crude oil revealed the relationship between the structure and activity of gemini surfactant additives. It is found that the x-ray diffraction patterns of waxes with additives are remarkably different from those without additives. The mechanism of the depressants action has been suggested according the adsorption of each additive. Adsorption of the additive on the surface of the wax particles inhibits their growth and alters the crystal habits through micelle core. Pretreatment of the crude oil with pour point depressants has received the greatest acceptance due to its simplicity and economy.

Synthesis, surface activity, and corrosion inhibition of dentritic quaternary ammonium salt-type tetrameric surfactants

ABSTRACTThe dentritic quaternary ammonium salt-type tetrameric surfactant (4C12tetraQ) was synthesized, and the molecular structure was confirmed by 1H NMR and FTIR. The surface activity of 4C12tetraQ was investigated by surface tension, and surface chemical parameters, such as critical micelle concentration (cmc), efficiency (pC20), effectiveness (πcmc), the surface tension value at cmc (γcmc), minimum surface area (Amin), maximum surface excess (Γmax), and cmc/C20 were obtained from the measurement results. The results show that the 4C12tetraQ surfactant has higher surface activity than the traditional monomeric surfactants (dodecyl trimethyl ammonium bromide, DTAB). The Krafft points were taken as <0°C, indicating that the synthesized tetrameric surfactants had good water solubility. Free energies of micellization and adsorption show that 4C12tetraQ display greater propensity to absorb at the interface than form micelle in the bulk of the aqueous solution, and that the two processes are spontaneous. The measurement results show that 4C12tetraQ has good emulsification power and foam performance. The corrosion efficiency was evaluated with the loss weight method in 1 mol/L HCl solution, and the results show that the 4C12tetraQ surfactant has good corrosion inhibition, and can be considered as a corrosion inhibitor.

FT-IR spectroscopic and micellization studies of cetyltrimethylammonium bromide in aqueous and aqueous solution of ionic liquid (1-butyl-3-methylimidazolium bromide) at different temperatures

The electrical conductivity and infrared spectroscopic measurement of aqueous solutions of cetyltrimethylammonium bromide (CTAB), cationic surfactant, with imidazolium based ionic liquid 1- butyl-3 methyl imidazolium bromide [C4mim] [Br] were determined at different weight percentages and temperatures. The temperature dependence of critical micelle concentration (cmc) obtained from conductivity measurements at different temperatures (298.15, 303.15, and 308.15) K has been used to calculate various thermodynamic parameters of micellization like standard enthalpy of micellization (ΔHm0), standard free energy of micellization (ΔGm0), and standard entropy of micellization (ΔSm0), and the obtained parameters are further used to understand the effect of ionic liquid on surfactant. The influence of ionic liquid 1-butyl-3-methylimidazolium Bromide [C4mim][Br] on the micellization process of the cetyltrimethylammonium bromide (CTAB) is discussed.

Synthesis, characterization, and physicochemical properties of a series of quaternary gemini surfactants with different spacer lengths

The study deals with the synthesis and characterization, as well as the adsorption and micellization behavior (including thermodynamics) in aqueous solution of a series of gemini surfactants with different spacer lengths. The synthesized surfactants were characterized by FTIR, 1H-NMR, FESEM, EDX, and TGA analyses. DLS measurements showed that micelles formed at critical micelle concentration (CMC) transformed into an assemblage of micelles and micellar agglomerates at higher concentrations. Surface tension was found to decrease with temperature and spacer length. However, CMC values increased with spacer length, as confirmed by surface tension and conductivity results. Surface adsorption parameters such as surface excess, minimum area, surfactant effectiveness, and efficiency were also determined. Gibbs free energy of adsorption (ΔG ads) value was found to be greater than Gibbs free energy of micellization (ΔG mic), showing that adsorption is more favored in aqueous gemini systems.

Influence of methanol and dimethyl sulfoxide and temperature on the micellization of cetylpyridinium chloride

The micellar behavior of cetylpyridinium chloride (CPC) in water and polar non-aqueous solvents has been investigated in the temperature range of 298.15–323.15K using conductivity methods. The specific conductivity versus concentration plot determines the micellization parameters using critical micelle concentration (CMC) and degree of counter-ion dissociation (α) of the micelle. It was observed that the micellization tendency of the surfactant decreases in the presence of solvents.Thermodynamic properties such as the standard free energy of micellization (∆Gmo), the standard enthalpy of micellization (∆Hmo), the standard entropy of micellization (∆Smo), the standard free energy of transfer (∆Gtranso) and the heat capacity of micellization (∆mCp°) of CPC are significantly affected by the addition of methanol and dimethyl sulfoxide (DMSO). The solvophobic parameter characterized by the Gibbs energy of transfer of hydrocarbons from gas into a given solvent can be used to account for the effect of methanol and DMSO on the formation and growth of the CPC aggregate in water.

Interactions of Cationic, Anionic and Nonionic Surfactants with Cresol Red Dye in Aqueous Solutions: Conductometric, Tensiometric, and Spectroscopic Studies

Abstract The interaction of cresol red (CR) with cetylpyridinium bromide (CPB), sodium dodecyl sulphate (SDS), and Triton X-100 (TX-100) was studied in aqueous solutions employing conductometric, tensiometric, and spectroscopic methods. Various micellar and interfacial parameters were calculated in absence and in presence of CR. The interactions suggest the formation of a CR-CPB adduct, an association of CR with the micelle of TX-100 while no adduct is formed between CR and SDS. Appreciably low critical micelle concentration, CMC value of TX-100 compared with those of CPB and SDS in pure water and drastic reduction of CMC of CPB (about one-twelfth of its value in pure water) than SDS and TX-100 in the presence of CR were observed. Higher negative values of Gibbs free energy of micellization, ΔG m 0, for all the three surfactants indicate that micellization process is spontaneous. The values of maximum surface excess concentration, Γ max, and minimum area per molecule, A min, suggest that in the presence of CR, the air-solution interface is closely packed and the orientation of surfactant molecules is almost perpendicular to the surface. UV-visible spectra suggest the formation of ion-pair complex between the dye CR and the monomers of CPB in the pre-micellar region, while above the CMC a breaking up of the ion-pair complex takes place and the dye is solubilized in the micelles of CPB. In the case of SDS the absorption spectra indicate weak interaction between CR and SDS molecules formation of H-bonding, short range dispersive forces, and hydrophobic interactions between CR and TX-100 molecules in the solution.

Composition of Surface Layer at the Water\u2013Air Interface and Micelles of Triton X-100\xa0+\xa0Rhamnolipid Mixtures

Measurements of the surface tensions, densities and viscosities of aqueous solutions of Triton X-100 (TX-100) and rhamnolipid (RL) mixtures, at constant concentration of RL or TX-100, were carried out. The measured values of the surface tension were compared to those determined using different theoretical models and on the basis of the surface tension of aqueous solutions of individual surfactants. From the surface tension isotherms, the Gibbs surface excess concentration of TX-100 and RL, the composition of surface layer and the standard Gibbs free energy of adsorption at the water–air interface were determined. Moreover, on the basis of surface tension, density and viscosity isotherms, the CMC of surfactants mixtures were evaluated. From the density isotherms, apparent and partial molar volumes of TX-100 and RL were also determined. These volumes were compared to those calculated from the sizes of TX-100 and RL molecules. There was observed a synergetic effect in the reduction of water surface tension and micelle formation, which was confirmed by the intermolecular interactions parameter. In the case of micelle formation, this effect was discussed based on the standard Gibbs free energy of micellization as well as of TX-100 and RL mixing in the micelles. The synergism of TX-100 and RL mixtures in the reduction of water surface tension and micelle formation was explained on the basis of electrostatic interactions between the hydrophilic part of TX-100 and RL molecules; this was supported by pH measurements.

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.