Increasing Mole Fraction Research Articles

Investigation of micellar and interfacial phenomenon of amitriptyline hydrochloride with cationic ester-bonded gemini surfactant mixture in different solvent media.

Herein, the interaction among the antidepressant drug amitriptyline hydrochloride (AMT) and a green gemini surfactant, ethane-1, 2-diyl bis(N,N-dimethyl-N-tetradecylammoniumacetoxy) dichloride (14-E2-14), via numerous techniques such as tensiometry, fluorimetry, FT-IR and UV-visible spectroscopy in three different media (aqueous 0.050 mol·kg-1 NaCl, 0.50 and 1.0 mol·kg-1 urea) were investigated. AMT is used to treat mental illness or mood problems, such as depression. The aggregation of biologically active ingredients can enhance the bioavailability of hydrophobic drugs. A significant interaction between AMT and 14-E2-14 was detected by tensiometric study as the critical micelle concentration (cmc) of AMT+14-E2-14 is reduced upon an increase of mole fraction (α1) of 14-E2-14. The decrease in cmc indicates the nonideality of studied mixtures of different compositions. Although, employed drug AMT is freely soluble in the aqueous and non-aqueous system but is not hydrophobic enough to act as its carrier. Instead, gemini surfactant formed spherical micelles in an aqueous system and their high solubilization capability, as well as their relatively lower cmc value, makes them highly stable in vivo. The cmc values of AMT+14-E-14 mixtures in all cases were further decreased and increased in NaCl and urea solutions respectively as compared with the aqueous system. Numerous micellar, interfacial, and thermodynamic parameters have been measured by applying various theoretical models. The obtained changes in the physicochemical assets of AMT upon adding of 14-E2-14 are likely to enhance the industrial and pharmaceutical applications of gemini surfactants. The negative interaction parameters (βm and βσ), indicate synergistic attraction is occurring in the mixed systems. The aggregation number (Nagg), Stern–Volmer constant (Ksv), etc. are attained through the fluorescence method, also supporting the attractive interaction behavior of AMT+14-E2-14 mixtures in all solvents. The Nagg was found to increase in the salt solution and decrease in the urea system compared with the aqueous solution. FT-IR and UV-visible analysis also depict the interaction between the constituent alike tensiometry and fluorimetry methods. The results suggested that gemini surfactants may serve as a capable drug delivery agent for antidepressants, improving their bioavailability.

Conductivity of 1-Ethyl-3-Methylimidazolium Chloride (EMIC) and Aluminum Chloride (AlCl3) Ionic Liquids at Different Temperatures and AlCl3 Mole Fractions

In this work, the conductivity (k) of Lewis acidic ionic liquid (IL) comprising a melt of organic chloride and aluminum chloride (AlCl3) with different molar ratios of organic chlorides with AlCl3 in the temperature range of 70-110 °C are reported. The ILs prepared with three imidazolium-based organic chlorides such as EMIC, BMIC, and HMIC are studied. The molar ratios of 1:1.5, 1:1.8, and 1:2.0 are selected for the study to maintain the acidity of the ILs for possible metal electrodeposition applications. The electrochemical behavior of anion species in the three ILs is studied using electrochemical impedance spectroscopy (EIS) technique and obtained the precise and fast measurement of conductivity values. The measured k values of all the ILs followed the Arrhenius law. The activation energies of conduction determined by fitting the experimental conductivity data are in good agreement with the literature. The conductivity of ILs with lower alkyl group organic chlorides decreased with the higher mole fraction of AlCl3. In contrast, the conductivity of IL having a higher alkyl group organic chloride (HMIC) increased with the increasing mole fraction of AlCl3. Based on the thermodynamic calculations, the differences in conductivities are attributed to the anion concentration, the molecular structure, cation-anion interactions, and hydrogen bonds in the ILs.

Insight into the Adsorption Mechanisms of CO2, CH4, and Their Mixtures on Kerogen Type IIIA

The mechanisms of adsorption of methane (CH4) and carbon dioxide (CO2) are still a challenge in CO2 sequestration with enhanced gas recovery (CS-EGR) in shale gas reservoirs. In this study, we focus on the adsorption behaviors of CO2 and CH4 on kerogen type IIIA using molecular dynamics (MD) and Grand Canonical Monte Carlo (GCMC) simulations. Simulation results indicated that the difference between the adsorption capacity of CO2 and CH4 increased with increase of mole fraction of CO2. The adsorption capacity of CO2/CH4 decreased with increase of the water content. Water showed a greater effect on the adsorption of CO2 than on that of CH4. The isosteric heat and adsorption selectivity of CO2/CH4 decreased at low water content and increased with increasing water content. This study provides certain theoretical guiding significance for the application of CS-EGR projects from a microscopic perspective.

Performance analysis of syngas production in a water thermal plasma reactor

Water thermal plasma gasification is a promising gasification technology aiming at providing sustainable disposal for various wastes. In this study, thermochemical modeling and optimization of a water thermal plasma reactor is carried out in order to enhance H2 and CO production from propane gasification. The novelty of present study is that the plasma reactor is considered as two connected partially stirred reactors for steam dissociation and propane gasification. Various detailed chemical mechanisms are evaluated against previously published experimental data and thermodynamic results. Influences of important parameters on syngas production, such as argon temperature and flow rate as well as steam and propane flow rates have been studied. It is found that the temperature and flow rate of argon have major impacts on hydrogen production due to changing the concentration of H radicals in the steam dissociation part. In particular, reducing argon temperature by 30% can result in 14% increase in H2 mole fraction. Also, 20% reduction in argon flow rate would increase H2 concentration by 9.5%. The present modeling approach will be useful in further investigations to improve the construction of a plasma reactor and defining best operational conditions for syngas production.

Low Noise Multiquantum Well DAR IMPATT Diodes Based On SiXGe1-X/Si

A Multiquantum Well (MQW) SixGe1-x/Si DAR (Double Avalanche Region) IMPATT (Impact Avalanche Transit Time) diode as a high power-high efficiency-low noise source at W-band is proposed in this paper. The RF power, conversion efficiency and noise of the device are optimized with respect to number of quantum wells and Ge mole fraction. The proposed device delivers peak power of 2.7 W, conversion efficiency of 7.5% and noise measure of 25 dB when the number of wells in the MQW structure is four and mole fraction of Ge is 0.3. The admittance plots of the device exhibit distinct negative conductance bands for three different (0.1, 0.2 and 0.3) mole fractions of Ge. An upward shift of optimum frequency is observed with increasing Ge mole fraction. The noise measure of the device decreases with increasing mole fraction of Ge and decreasing current.

Photon Activation of Glassy Dynamics: A Mechanism for Photoinduced Fluidization, Aging, and Information Storage in Amorphous Materials.

We discuss the photon activation of structural relaxations in glassy melts and frozen glasses containing molecules that can photoisomerize. The built-in stress following a photoinduced electronic transition lowers the thermal activation barrier for subsequent structural reconfiguration of the glassy matrix. We provide explicit predictions for the barrier distribution and structural relaxation spectrum as functions of the concentration of photoactivated molecules and the fragility of the material. The typical barrier decreases upon photoactivation, while the barrier distribution increases in width with increasing mole fraction of photoactive molecules and fluence, and becomes multimodal. In a frozen glass, the initial effects of photoisomerization locally facilitate the dynamics near the excited chromophores and can lead to complete fluidization at a sufficiently high fluence. Photon activation initially decreases the yield strength of the glass. Depending on the precise time course of illumination, there however emerges a spatial coexistence of softened regions with regions that, after being destabilized by illumination, have reconfigured so that they are now made of ultrastable glass or have crystallized as in a porcelain. This sequence of events, after illumination, can lead to highly stable amorphous solids, potentially approaching the Kauzmann limit. These mechanisms are at the root of optical information storage technologies in amorphous materials.

On the Second Explosion Limits of Hydrogen, Methane, Ethane, and Propane.

In this work, we have first investigated the explosion limit behaviors from hydrogen to propane through numerical simulations and validated with the available experimental data. The shape of the explosion limit curves and the possible turning points (P1–2, T1–2), first to second limit transition, and (P2–3, T2–3), second to third limit transition that bound the second explosion limit as a function of the fuel carbon number, have been examined. Results show that with an increase of methane mole fraction in the hydrogen/methane system, the upper turning point (P1–2, T1–2) remains almost unchanged and the lower transition point (P2–3, T2–3) rotates counterclockwise around (P1–2, T1–2). With a further increase of carbon number, (P1–2, T1–2) moves to the lower-pressure and -temperature region and (P2–3, T2–3) gradually moves to the lower-pressure and higher-temperature region. The slope of the second explosion limit is inversely proportional to the carbon number, kPT = 0.0069 – 0.005/(Xc – 0.7), approximately. Second, a sensitivity analysis has been conducted to study the elementary reaction on the second explosion limits. The results show that the chain branching and termination reactions governing the explosion limit of hydrogen have a little effect on the second explosion limit of methane. The C2H5O2H decomposition to form OH radicals is dominant in controlling the nonmonotonic behavior of the second explosion limit of C2H6. The second explosion limit behavior of propane is governed by three sets of reactions in the low-temperature oxidation process.

Condensation heat transfer characteristics of moist air outside a three-dimensional finned tube

The condensation heat transfer of moist air is a common phenomenon in industry processes, and improving the efficiency of condensation heat transfer is a common focus of research. Many studies have shown that extending the surface of the heat exchanger can effectively enhance the condensation heat transfer efficiency. Therefore, this study focused on a three-dimensional (3-D) finned tube heat exchange element with an extra-large extended surface, and experiments were conducted to study the condensation heat transfer characteristics of moist air outside the 3-D finned tube. The effects of different steam mole fractions, moist air velocities, cooling water inlet temperatures, and moist air temperatures on the condensation heat transfer characteristics of the moist air outside the 3-D finned tube were studied under atmospheric pressure. A smooth tube was also tested under the same conditions for comparison. The experimental results showed that the 3-D finned tube can achieve a higher heat transfer coefficient compared with the smooth tube under all tested conditions. Moreover, for both the 3-D finned tube and the smooth tube, the heat transfer coefficient increased with an increase in the steam mole fraction and moist air velocity, and decreased with an increase of moist air temperature or cooling water inlet temperature. Furthermore, in a single-phase convective heat transfer case, the 3-D finned tube could achieve 3.1 times the heat transfer coefficient of the smooth tube. In a moist air condensation heat transfer case, the 3-D finned tube could achieve 1.7 times the heat transfer coefficient of the smooth tube when the steam mole fraction was 0.05. Although the 3-D finned tube had a more serious condensate retention phenomenon compared with that of the smooth tube, the 3-D fins could still increase the heat transfer area and effectively break the flowing boundary layer outside the tube wall. In addition, the 3-D finned tube had a higher heat transfer coefficient compared with the smooth tube.

Condensation heat transfer characteristics of moist air outside 3-D finned tubes with different wettability

Abstract The condensation heat transfer of moist air plays an important role in industries and daily life. However, the presence of non-condensable gases makes it difficult for steam to condensate on a cooling surface. According to previous studies, a three-dimensional (3-D) finned tube and dropwise condensation can both increase the heat transfer performance. To increase the condensation heat transfer of moist air, this study combined these two methods and experimentally studied the condensation heat transfer of moist air outside 3-D finned tubes with different wettability values. The effects of the 3-D fins and surface wettability on the heat transfer process under different steam mole fractions, moist air temperatures, and cooling water inlet temperatures were determined and analysed in detail. The experimental results showed that a hydrophilic 3-D finned tube could achieve the highest heat transfer coefficient, which was up to 94% higher than that of a hydrophilic smooth tube. In addition, the heat flux and heat transfer coefficient increased with decreases in the moist air temperature and cooling water inlet temperature, or with an increase in the steam mole fraction. Droplet retained between 3-D fins increased the diffusion resistance of water steam and the conductive thermal resistance.

Solvation structures of Na+ Cl− ion pair in DMF-water and DMF-methanol mixtures

ABSTRACT We have studied the solvation structures of Na+ Cl− ion pair in DMF (dimethyl formamide)-water and DMF-methanol binary mixtures using constrained molecular dynamics technique. The resulting potentials of mean force shows prominent minima corresponding to contact ion pairs (CIPs) and solvent assisted ion pairs (SAIPs) in all mole fractions of DMF except in pure DMF. The stabilities of CIPs increase with an increase in mole fraction of DMF in both the binary mixtures. The CIPs in DMF-methanol mixtures are more stable than the CIPs in DMF-water mixtures. The formation of the ion pair is found to be entropically driven in both the mixtures. Preferential solvation analysis through excess coordination numbers shows that Na+ and Cl− are preferentially solvated by water in DMF-water and by methanol in DMF-methanol binary mixtures. The rate of dissociation of the ion pair is larger in DMF-water mixtures than in DMF-methanol mixtures.

Density and Speed of Sound of Diethylene Glycol Monoethyl Ether + Propylene Glycol at T = (288.15–318.15) K

Thedensity(ρ) and speed of sound (u)of the binarymixture (diethylene glycol monoethyl ether (carbitol) + propylene glycol (PG)) have been reported at T= (288.15, 298.15, 308.15 and 318.15) K. The excess molar volume ( ) and isentropic compressibility deviation (Δκs) were calculated using the measured data. The obtained values of ( ) and (Δκs) are negative and positive, respectively, and become more negative and more positive with an increase in carbitol mole fraction. The ρ, u, Vm and κs values of the mixture were correlated by the Jouyban-Acree model with high accuracy. Furthermore, the calculated and Δκs values were correlated well by the Redlich-Kister equation.

Long-term reliability of the Figaro TGS 2600 solid-state methane sensor under low-Arctic conditions at Toolik Lake, Alaska

Abstract. The TGS 2600 was the first low-cost solid-state sensor that shows a response to ambient levels of CH4 (e.g., range ≈1.8–2.7 µmol mol−1). Here we present an empirical function to correct the TGS 2600 signal for temperature and (absolute) humidity effects and address the long-term reliability of two identical sensors deployed from 2012 to 2018. We assess the performance of the sensors at 30 min resolution and aggregated to weekly medians. Over the entire period the agreement between TGS-derived and reference CH4 mole fractions measured by a high-precision Los Gatos Research instrument was R2=0.42, with better results during summer (R2=0.65 in summer 2012). Using absolute instead of relative humidity for the correction of the TGS 2600 sensor signals reduced the typical deviation from the reference to less than ±0.1 µmol mol−1 over the full range of temperatures from −41 to 27 ∘C. At weekly resolution the two sensors showed a downward drift of signal voltages indicating that after 10–13 years a TGS 2600 may have reached its end of life. While the true trend in CH4 mole fractions measured by the high-quality reference instrument was 10.1 nmolmol-1yr-1 (2012–2018), part of the downward trend in sensor signal (ca. 40 %–60 %) may be due to the increase in CH4 mole fraction because the sensor voltage decreases with increasing CH4 mole fraction. Weekly median diel cycles tend to agree surprisingly well between the TGS 2600 and reference measurements during the snow-free season, but in winter the agreement is lower. We suggest developing separate functions for deducing CH4 mole fractions from TGS 2600 measurements under cold and warm conditions. We conclude that the TGS 2600 sensor can provide data of research-grade quality if it is adequately calibrated and placed in a suitable environment where cross-sensitivities to gases other than CH4 are of no concern.

Experimental and numerical study on filmwise condensation of pure propane and propane/methane mixture

The condensation process of pure propane and propane/methane mixture on the vertical plate were experimentally and numerically researched to clarify the condensation characteristics at the first stage of natural gas liquification. In this work, a visualization experimental system was designed to study the flow pattern and heat transfer characteristics of propane vapor condensation on the vertical plate. The condensate film on the plate is wave laminar flow on the experimental conditions of liquid film Reynolds number from 59 to 321. With the increase of the liquid film Reynolds number, the flow patterns turn from straight isolated waves (about 8-10 mm length) to dense and short waves, which enhances the condensation heat transfer coefficient. At the same time, a 2-D numerical model was proposed to reveal the condensation mechanism of propane and propane/methane mixture with different wall subcooled temperature (5-40 K) and methane mole fraction (80%-95%). The numerical results agree well with the experimental data. And the results show that 80% methane reduces the liquid film thickness approximately by half comparing with the pure propane. The increase of methane mole fraction could reduce the liquid film thickness, but its contribution to the heat transfer is negligible compared with the mass diffusion resistance caused by the gas boundary layer. The heat transfer coefficient decreases beyond ninety percent compared with pure propane at the methane mole fraction of 80–95%.

Influence of Cross-Linking Degree on Hydrodynamic Behavior and Stimulus-Sensitivity of Derivatives of Branched Polyethyleneimine.

Cross-linked derivatives of acylated branched polyethyleneimine containing 2-isopropyl-2-oxazoline units were investigated in chloroform and aqueous solutions using methods of molecular hydrodynamics, static and dynamic light scattering, and turbidity. The studied samples differed by the cross-linker content. The solubility of the polyethyleneimines studied worsened with the increasing mole fraction of the cross-linker. Cross-linked polyethyleneimines were characterized by small dimensions in comparison with linear analogs; the increase in the cross-linker content leads to a growth of intramolecular density. At low temperatures, the aqueous solutions of investigated samples were molecularly dispersed, and the large aggregates were formed due to the dehydration of oxazoline units and the formation of intermolecular hydrogen bonds. For the cross-linked polyethyleneimines, the phase separation temperatures were lower than that for linear and star-shaped poly-2-isopropyl-2-oxazolines. The low critical solution temperature of the solutions of studied polymers decreased with the increasing cross-linker mole fraction. The time of establishment of the constant characteristics of the studied solutions after the jump-like change in temperature reaches 3000 s, which is at least two times longer than for linear polymers.

Stabilization performances and mechanisms of a diffusion‐like vortex‐tube combustor foroxygen‐enrichedcombustion

The stabilization performance and mechanisms in a diffusion-like vortex-tube combustor is investigated for oxygen-enriched combustion. The stability limit, flame configuration, and pressure fluctuation are investigated under various conditions. Results show that a diffusion-like flame structure is established in the combustor and the nonpremixed peculiarity becomes more prominent with the increase of oxygen mole fraction. The steady combustion can be achieved in the range of global equivalence ratio 0.01 to 1.0 with a low-pressure fluctuation amplitude always less than 1300 Pa, indicating a good combustion stability of this combustor. Additionally, the stabilization mechanism is discussed from the time matching and velocity matching. Based on the axial fuel entry method, the Damköhler number (Da) is always less than 1.0 as a whole, which is the principal reason for the tubular flame shape and the steady combustion procedure in this vortex-tube combustor. The intensified combustion under oxygen-enriched combustion can increase the flame speed, and subsequently reduce the mixing quality and make the yellow flame more visible. Besides, the temperature distribution and the flow field structure can explain the corrugation and deformation of the flame front under oxygen-enriched conditions.

Reaction kinetics investigation of Malononitrile with substituted benzaldehydes in aqueous solutions of ethaline as deep eutectic solvent

AbstractDue to increasing demands for ecofriendly processes within the framework of green chemistry, and having shown substantial properties, especially in terms of toxicity, biodegradability, cost, and ease of preparation under ambient conditions, deep eutectic solvents (DESs) have become a suitable candidate as green solvents for reaction media in the past decade. In this work, condensation reaction of some para‐ and meta‐substituted benzaldehydes and Malononitrile was kinetically investigated in ethylene glycol‐choline chloride (ethaline) as a DES mixed with water, in the whole range of mole fractions, at room temperature. The correlation of second‐order rate coefficients based on Hammett's substituent constants yield a linear straight line with positive slope in different mole fractions of ethaline–water mixtures. The measured second‐order rate coefficients of the reaction showed a dramatic variation in ethaline–water mixtures with the increasing mole fraction of water.

Energy and cost estimates for separating and capturing CO2 from CO2/H2O using condensation coupled with pressure/vacuum swing adsorption

Condensation coupled with pressure swing adsorption (CPSA) and condensation coupled with vacuum swing adsorption (CVSA) were used to separate CO2 from CO2/H2O mixtures. Six methods are compared using numerical simulations in terms of the energy consumption, separation efficiency and total annual costs for separating CO2/H2O mixtures. The effects of inlet CO2 mole fraction, mass flow rate, and pressure on the total annual cost are also studied. A parametric study shows that the total annual costs of all these methods increase as the CO2 mole fraction and mass flow rate increase and decrease with increasing inlet gas pressure. In addition, for CO2/H2O mixtures with inlet pressure of 10 kPa, mass flow rate of 40 kg/s, and CO2 mole fraction of 0.1, the average heat rejection of the CPSA processes is higher than that of the CVSA process. Although the CPSA recovery (90.02%) is much lower than that of CVSA (96.26%), the H2O remove efficiencies of Adsorption for CPSA and CVSA are very close, because that the remained amount of H2O before Adsorption is very little. A type of CVSA named CcCVSA has the lowest total annual cost with this being the recommended system.

Micellization and Solvation Properties of Newly Synthesized Imidazolium- and Aminium-Based Surfactants

This work aimed to study the solvation properties of newly synthesized cationic surfactants: 1-hexyl-1-methyl-1H-imidazol-1-ium bromide (R6Im), 1-dodecyl-1-methyl-1H-imidazol-1-ium bromide (R12Im), N,N,N-tributylhexan-1-aminium bromide (R6N4), and N,N,N-tributyldodecan-1-aminium bromide (R12N4) in water and ethanol–water solvents with a 0.237 mole fraction of ethanol at 298.15 K using conductivity, refractive index, surface tension, and density measurements. Critical micelle concentration (CMC) for the synthesized surfactants was determined and discussed. Thermodynamic parameters including association constant, molal volume, and polarizability were calculated and discussed. Some surface properties of surfactants including excess surface concentration and minimum area per molecule were also calculated and discussed. A good agreement was found between the CMC values obtained from different techniques, such as conductivity, refractive index, and surface tension. Imidazolium surfactants had been proved to decrease the CMC and increase the association constant with the increase of ethanol mole fraction, while tributylamine had been proved to increase the CMC and decrease the association constant with the increase of ethanol mole fraction. Also, imidazolium surfactants had been proved to have higher CMC than tributylamine, which may be related to higher solvation of imidazolium surfactants than that of tributylamine. Both surfactants (R12Im) and (R12N4) were proved to have lesser CMC.

Experimental and numerical study of the effect of elevated pressure on laminar burning velocity of lean H2/CO/O2/diluents flames

Laminar burning velocities (SL) of H2/CO/O2/diluents (He or N2) were reported at lean conditions (ϕ = 0.5–1.0), elevated pressures (1–11 bar) and a wide range of H2-CO volumetric ratios. A new high-pressure rig based on specially designed heat flux burner was applied to obtain planar, adiabatic and stretch-less flames used for laminar burning velocity measurements. Five popular syngas oxidation mechanisms were tested against the obtained SL data and showed satisfactory agreement even at high pressures up to 11 bar. SL decreases as pressure increases while the negative pressure dependence of mass burning rate is experimentally and numerically found for syngas with high diluent content in the oxidizer or high hydrogen content in the fuel, which indicated the negative dependence of the overall reaction order on adiabatic flame temperature. Sensitivity and rate of production analyses indicated that the sensitivity coefficients and HO2 mole fraction increase to the maximum at the pressure of the minimum overall reaction order and then decreases, which leads to larger uncertainty on predicting SL at higher pressures. The flame front height represented by the peak OH* chemiluminescence location also shows a non-monotonic variation trend as pressure increases and can serve as a target for mechanism validation.

Theoretical Approaches on the Synergistic Interaction between Double‐Headed Anionic Amino Acid‐Based Surfactants and Hexadecyltrimethylammonium Bromide

AbstractTheoretical investigations on the micellization of mixtures of (i) amino acid‐based anionic surfactants [AAS: N‐dodecyl derivatives of aminomalonate, −aspartate, and ‐glutamate] and (ii) hexadecyltrimethylammonium bromide (HTAB), were carried out at different mole ratios. Variation in the theoretical values of critical micelle concentration (CMC), mole fraction of surfactants in the micellar phase (X), at the interface (Xσ), interaction parameters at the bulk/interface (βR/βσ), ideality/nonideality of the mixing processes, and activity coefficients (f) were evaluated using Rubingh, Rosen, Motomora, and Sarmoria‐Puvvada‐Blankschtein models. CMC values significantly deviate from the theroretically calculated values, indicating associative interaction. With increasing mole fraction of AAS (αAAS), the magnitude of the (βR/βσ) values gradually decreased, considered to attributable to hydrophobic interactions. With increasing αAAS, the micellar mole fraction of HTAB (X2) decreased insignificantly and X2 values were higher than those compared to AAS for all combinations, due to the dominance of HTAB in micelles. Micellar mole fraction at the ideal state of AAS () differed from micellar mole fraction of AAS (X1), indicating nonideality in the mixed micellization process. Gibbs free energy of micellization ( ∆Gm) values are more negative than the free energy of micellization for ideal mixing (), indicating the micellization process is spontaneous. With increasing αAAS, the enthalpy of micellization (ΔHm) and entropy of micellization (ΔSm) values gradually increased, which indicates micellization is exothermic. The different physicochemical parameters of the mixed micelles are correlated with the variation in the spacer length between the two carboxylate groups of AAS.