Anionic Surfactant Solutions Research Articles

Nanoparticle-stabilized CO2 foam flooding for enhanced heavy oil recovery: A micro-optical analysis

Surfactant flooding is a well-known chemical approach for enhancing oil recovery. Surfactant flooding has the disadvantage that it cannot withstand the harsh reservoir conditions. Improvements in oil recovery and release are made possible by the use of nanoparticles and surfactants and CO2 co-injection because they generate stable foam, reduce the interfacial tension (IFT) between water and oil, cause emulsions to spontaneously form, change the wettability of porous media, and change the characteristics of flow. In the current work, the simultaneous injection of SiO2, Al2O3 nanoparticles, anionic surfactant SDS, and CO2 in various scenarios were evaluated to determine the microscopic and macroscopic efficacy of heavy oil recovery. IFT (interfacial tension) was reduced by 44% when the nanoparticles and SDS (2000 ppm) were added, compared to a reduction of roughly 57% with SDS only. SDS-stabilized CO2 foam flooding, however, is unstable due to the adsorption of SDS in the rock surfaces as well as in heavy oil. To assess foam's potential to shift CO2 from the high permeability zone (the thief zone) into the low permeability zone, directly visualizing micromodel flooding was successfully executed (upswept oil-rich zone). Based on typical reservoir permeability fluctuations, the permeability contrast (defined as the ratio of high permeability to low permeability) for the micromodel flooding was selected. However, the results of the experiment demonstrated that by utilizing SDS and nanoparticles, minimal IFT was reached. The addition of nanoparticles to surfactant solutions, however, greatly boosted oil recovery, according to the findings of flooding studies. The ultimate oil recovery was generally improved more by the anionic surfactant (SDS) solution including nanoparticles than by the anionic surfactant (SDS) alone.

Synergisms between Surfactants, Polymers, and Alcohols to Improve the Foamability of Mixed Systems

In order to produce detergents with improved performance and good market acceptability, it is crucial to develop formulations with improved foamability and cleaning performance. The use of a delicate balance of surfactants and additives is an appealing strategy to obtain good results and enables a reduction in the amount of chemicals used in formulations. Mixtures of hydrophobically modified linear polymers and surfactants, as well as balanced mixtures with co-surfactants and/or hydrotropes, are the most effective parameters to control foamability and foam stability. In the present study, the effect of the addition of hydrophobically modified linear polymers, nonionic co-surfactants and hydrotropes, and their mixtures to anionic and zwitterionic surfactant aqueous solutions was evaluated. It was found that the presence of the hydrophobically modified polymer (HM-P) prevented the bubbles from bursting, resulting in better stability of the foam formed using zwitterionic surfactant solutions. Also, the surfactant packing was inferred to be relevant to obtaining foamability. Mixtures of surfactants, in the presence of a co-surfactant or hydrotrope led, tendentially, to an increase in the critical packing parameter (CPP), resulting in higher foam volumes and lower surface tension for most of the studied systems. Additionally, it was observed that the good cleaning efficiency of the developed surfactant formulations obtained a higher level of fat solubilization compared to a widely used brand of commercial dishwashing detergent.

Promote or inhibit turbulence drag reduction behavior of surfactant solutions with different micelle structures by certain nanoparticle addition

The micelle structure of surfactant is easy to be destroyed in the flow process resulting in a decrease in its drag reduction (DR) efficiency; therefore, how to strengthen the stability of the micelle structure during the flow process and thus improve the drag reduction efficiency deserves intensive research. In this work, by comparing a variety of nanoparticles, hydrophobic silica nanoparticles were selected as the best additive to enhance the turbulence drag reduction efficiency of surfactant solution with spherical micelle structure. The experimental results also demonstrated that the hydrophobic silica nanoparticles had a reinforcing effect on anionic, cationic, nonionic, and zwitterionic surfactant solutions with the same concentration (dominated by spherical micelles), and the optimal nanoparticle addition concentration and maximum drag reduction rate were obtained. Meanwhile, the effect of silica nanoparticles on the turbulence drag reduction efficiency of surfactant solutions with different micelle structures was evaluated by inducing the surfactant micelle structure change. It was shown that the hydrophobic silica nanoparticles had a strengthening effect on the turbulence drag reduction performance of surfactant solutions with spherical micelle structure, while they had an inhibiting effect on the turbulence drag reduction performance of surfactant solutions with worm-like micelle structure. The change in solution viscoelasticity indicated that the decrease in viscoelasticity was the main reason for the decrease in drag reduction efficiency of surfactant solution with worm-like micelle structure when silica nanoparticles were added. A mechanism for the interaction of hydrophilic/hydrophobic silica nanoparticles with spherical micelles and wormlike micelle structures was finally discussed and proposed.

Oil spill dispersant formulation from Palmitoyl-DEA and methyl ester sulfonate

Surfactants are chemical compounds that can interact with solvents to reduce surface tension. Palmitoyl-Diethanolamide surfactant (Palmitoyl-DEA) and methyl ester sulfonate (MES) can be applied in dispersing oil in seawater as Oil Spill Dispersant (OSD). An OSD formulation derived from a mixture of two surfactant solutions, namely Palmitoyl-DEA and MES, was found. Diethanolamide non-ionic surfactant solution and anionic methyl ester sulfonate surfactant solution in various concentrations were mixed according to their respective ratios at 50℃ for 60 minutes. The OSD product obtained was then analyzed for density, surface tension, and emulsion stability. OSD products at a concentration of 4% MES and 2% DEA with a 2:1 ratio obtained the best analytical results. The OSD product has excellent density, surface tension, and emulsion stability (> 80%). Furthermore, testing of OSD products was carried out for oil pollution in seawater. The results of simulation tests using OSD products for handling petroleum pollution in seawater (15 mL/L) show an excellent ability to disperse oil (> 90%). The oil and OSD dispersed in seawater showed a more significant increase in COD and BOD values.

Refractive index, conductometric, and fluorescence probe study on interaction of valine with aqueous solution of anionic surfactant, sodium dodecyl surfactant (SDS), at 298.15, 303.15, 308.15 and 313.15 K

Refractive index, conductometric, and fluorescence probe study on interaction of valine with aqueous solution of anionic surfactant, sodium dodecyl surfactant (SDS), at 298.15, 303.15, 308.15 and 313.15 K

Impact of anionic synthetic surfactants of lead ions and their combinations on the pigment profile of freshwater plant organisms Ceratophyllum demersum and Egeria densa

The development of human civilization inevitably leads to the development of production with increasing emissions of many chemicals into the environment. This is especially noticeable in relation to surface waters of fresh water bodies. A very alarming point is that the amount of toxic anthropogenic substances, including heavy metals, is growing every year and is increasingly disturbing the existing ecological balance. Plant organisms of water bodies are among the first to experience the effects of any anthropogenic pollutants and especially heavy metals and surfactants, the amount of which increases in the water of rivers and lakes. Very important in this is the complex of morpho-physiological adaptations associated with restructuring in the structure of chloroplasts. Changes in the content of photosynthetic pigments in plants of two species (Ceratophyllum demersum and Egeria densa) were assessed when they were exposed to very common technogenic substances (lead ions and a solution of anionic synthetic surfactants). In plants, there is a decrease in the activity of molecular transport, inhibition of H+-ATPase, leading to a decrease in the pH of the cytoplasm and activation of hydrolases, which enhance the breakdown of biopolymers. This leads to changes in the expression of individual genes and increased synthesis of a number of stress proteins. Under these conditions, the assembly of cytoskeletal elements is activated, the structures of membrane proteins and lipids change, the level of ATP decreases, free radical processes are activated and the intensity of photosynthesis is inhibited.

Impact of anthropogenic toxic substances on the antioxidant defense of Ceratophyllum demersum and Egeria densa

Considering the current increase in anthropogenic pollution of the environment, it becomes necessary to monitor the qualitative and quantitative aspects of the impact of pollution on various biological objects. Of great practical interest are the toxic effects of technogenic discharges on various hydrobionts and the basic mechanisms of their development in macrophyte plants. In this regard, this work studied the influence of heavy metal ions, anionic synthetic surfactants and their combinations on the activity of the main antioxidant enzymes in the tissues of Ceratophyllum demersum and Egeria densa. An experiment was conducted to assess changes in the freshwater macrophytes Ceratophyllum demersum and Egeria densa. The activity of antioxidant enzymes was taken into account: peroxidase, polyphenol oxidase, ascorbate oxidase and catalase. Their activity was assessed basally and in response to chemical stressors (100 µmol/l lead ions, 1% solution of anionic synthetic surfactants) individually and in combination with different exposures to toxic substances. The identified features of enzymatic activity in the tissues of aquatic macrophytes indicate different levels and power of their antioxidant protection. It has been noted that the activity of antioxidant enzymes when plants are exposed to certain types of pollutants and their combinations is determined by the chemical nature of the pollutant, the mechanism of its action on the plant organism, the duration of exposure and the localization of these enzymes in cell compartments.

Physicochemical study on interaction of valine with aqueous solution of anionic surfactant, sodium dodecyl surfactant (SDS), at 298.15, 303.15, 308.15 and 313.15 K temperatures

Physicochemical study on interaction of valine with aqueous solution of anionic surfactant, sodium dodecyl surfactant (SDS), at 298.15, 303.15, 308.15 and 313.15 K temperatures

Effect of surfactant frequently used in soil flushing on oxygen mass transfer in micro-nano-bubble aeration system

In-site soil flushing and aeration are the typical synergetic remediation technology for contaminated sites. The surfactant presented in flushing solutions is bound to affect the aeration efficiency. The purpose of this study is to evaluate the effect of surfactant frequently used in soil flushing on the oxygen mass transfer in micro-nano-bubble (MNB) aeration system. Firstly, bio-surfactants and chemical surfactants were used to investigate their effects on Sauter mean diameter of bubble (dBS), gas holdup (ε), volumetric mass-transfer coefficient (kLa) and liquid-side mass-transfer coefficient (kL) in the MNB aeration system. Then, based upon the experimental results, the Sardeing’s and Frössling’s models were modified to describe the effect of surfactant on kL in the MNB aeration. The results showed that, for the twenty aqueous surfactant solutions, with the increase in surfactant concentration, the value of dBS, kLa and kL decreased, while the value of ε and gas–liquid interfacial area (a) increased. These phenomena were mainly attributed to the synergistic effects of immobile bubble surface and the suppression of coalescence in the surfactant solutions. In addition, with the presence of electric charge, MNBs in anionic surfactant solutions were smaller and higher in number than in non-ionic surfactant solutions. Furthermore, the accumulation of surfactant on the gas–liquid interface was more conspicuous for small MNB, so the reduction of kL in anionic surfactant solutions was larger than that in non-ionic surfactant solutions. Besides, the modified Frössling’s model predicted the effect of surfactant on kL in MNB aeration system with reasonable accuracy.

Experimental investigation on the effect of nanoparticles on surfactant flooding performance in resin-based 3D printed porous media

Adding nanoparticles (NPs) into surfactant solutions represents a promising strategy for enhancing oil displacement in porous media, with significant implications for various engineering and environmental applications, including soil remediation and enhanced oil recovery from underground reservoirs. Recent investigations have focused on the integration of silica and alumina NPs into anionic surfactant solutions to mitigate interfacial tension (IFT) and reduce the contact angle between the surfactant and oil phases. However, the utilization of these injection scenarios in fractured porous media has received limited attention. In this experimental study, we employed a 3D printer to design and fabricate three distinct porous media types: single permeability (S), fractured (F), and dual permeability (D). Subsequently, we prepared the sodium dodecyl sulfate (SDS) solution by adding SDS powder into a brine solution containing 2% NaCl. Nanofluids were then produced through the dispersion of SiO2 and Al2O3 NPs in the SDS solution using a sonicator. The prepared solutions were subsequently injected into each porous medium, while the recovery process was recorded using a camera. Recovery rates for each scenario were calculated utilizing a developed Python image processing code. Furthermore, analysis of the images enabled us to demonstrate the behavior and growth of the displacing phase’s fingers within the oil phase. Findings from this study showed that SDS injection into the S medium resulted in an approximate 60% oil recovery. Adding silica and alumina NPs into the SDS solution led to enhanced total recovery rates of up to 70% and 78%, respectively. The recovery results obtained from tests conducted within the F medium exhibited a pronounced decrease, with the SDS solution sweeping a mere 25% of the medium, while the silica and alumina nanofluids recovered 43% and 47%, of the oil respectively. Notably, the silica nanofluid displayed superior performance to the alumina nanofluid during the breakthrough stage in the F medium. In the D medium, the injection of SDS, silica, and alumina nanofluids achieved total recovery rates of 49%, 53%, and 56%, respectively. These outcomes highlight the diminished effectiveness of nanofluids within the dual permeable medium.

Experimental study on the synergic effects of surfactants and nanoparticles on the seepage of water injected into coal seams

To study the synergic effects of surfactants and nanoparticles on the seepage of water injected into coal seams, we prepared three chip models with complex cracks using glass etching technology based on the real conformation of cracks in coal mass and set up a visual experimental platform for microscopic seepage. Based on these models, we carried out a series of seepage experiments on gas expelling with different solutions and investigated the effects of surfactants, nanoparticles, and flow velocities on seepage characteristics. The results showed that all tested anionic, non-ionic, and cationic surfactant solutions could reduce flow resistance, showing a downward trend with the rise of the mass fractions of these surfactants. The combination of nanoparticles with these surfactant solutions further reduced flow resistance, showing the best drag reduction effects with hydrophobic nanoparticles at all tested flow velocities. Moreover, all three tested surfactants could displace gas and reduce gas residue in the crack networks. The higher the mass fraction of the surfactant solution is, the more significant the gas displacement effect. Furthermore, the gas displacement effect of the surfactant solution is positively proportional to the flow velocity. The higher the flow velocity is, the more significant the gas displacement effect.

Influence of anionic surfactant on stability of nanoparticles in aqueous solutions

Dispersion and aggregation of nanoparticles in aqueous solutions are important factors for safe and effective application of nanoparticles, for instance, in the oil industry. As conventional oil reserves are depleted, it is necessary to advance chemical enhanced oil recovery (cEOR) techniques to develop unconventional oil reservoirs. Nanoparticles modified by surfactants can be a promising reagent in cEOR. These nanomaterials can reduce interfacial tension and change the wettability of reservoir rock, which leads to an increase in oil recovery. However, the application of nanoparticles is limited by their substantial aggregation in aqueous solutions. The purpose of this work is to select nanoparticles for obtaining stable sols in water in the presence of an anionic surfactant and to optimize the conditions (pH) for further modifying the nanoparticles with the anionic surfactant. Sodium dodecyl sulfate (SDS) is used as an anionic surfactant. The aggregation of oxide and carbon nanoparticles in water and anionic surfactant solutions was studied by laser diffraction, dynamic and electrophoretic light scattering methods. Most of the studied nanoparticles in water form aggregates with bi-, three- and polymodal particle size distributions. TiO2 nanoparticles obtained by plasma dynamic synthesis form the most stable sols in anionic surfactant solutions. The range of 5–7 pH is defined as optimal for their modification with surfactants. The stability of carbon nanoparticles in aqueous solutions increases significantly in the presence of a surfactant. The obtained results form the basis for further research on the modification of marked nanoparticles in surfactant solutions.

A study on soil conditioning for cohesive soils with high content of clay minerals: Microscopic simulation and laboratory experiment

An earth pressure balance shield machine (EPB) is prone to blockage when tunneling in strata with high clay mineral content. Engineers often improve soil fluidity and reduce soil adhesion through soil conditioning to ensure the safe and efficient tunneling of shields. This paper selected montmorillonite, kaolinite, and illite as research objects and used molecular dynamics simulation and laboratory experiments. The interfacial mechanical behavior between anionic surfactant (sodium dodecyl benzene sulfonate, SDBS) solution and clay minerals was simulated at the microscopic scale and the improvement mechanism of SDBS solution on clay minerals was revealed. Then, the zeta potential of clay minerals and the stirring torque of the soil under different foam injection ratios (FIR) were tested. Accordingly, the conditioning effect of the SDBS solution at the macroscopic scale can be evaluated. The results show that the electrostatic adsorption and repulsion of ions occur on the surface of clay minerals, which makes it difficult for clay particles to aggregate into clusters. The SO3H- groups of the SDBS surfactant are the key factor to change the hydrophilicity of clay minerals. When different soil samples are improved to the same state, montmorillonite requires the largest FIR due to its microstructure.

Effects of static magnetic field on the surface tension of surfactant solutions

AbstractThe magnetic field (MF) effects resulting from water or solution treatments are still of significant interest. However, a relatively small number of papers have been published dealing with the pure surfactant solutions alone. On the other hand, surfactants are applied in many industrial processes as well as in everyday life and are also present in different waste waters. Therefore, it seemed interesting to investigate whether some effects would appear after the MF treatment of pure aqueous surfactant solutions. In the earlier published papers after MF action the changes in water evaporation rate and the surface tension were found for both the cationic dodecyltrimethylammonium bromide (DTAB) and anionic sodium dodecyl sulfate (SDS) solutions. The gradient MF originated from three connected ring magnets inside which the solutions were placed. The objective of this paper is to study whether using the same magnets but in a different position the effects of the MF are observed. The given surfactant solution in a closed vessel was placed in an uniform MF when the magnets were in the “lying” position. The investigated solutions on the magnet surface remained for 24 h. In this paper, despite SDS and DTAB also the cationic hexadecyltrimethylammonium bromide (CTAB) and nonionic Triton X‐100 solutions were applied. It appeared that in the uniform MF the surface tension of cationic and anionic surfactant solutions changes. However, larger changes were observed in the gradient MF. Generally, the changes of surface tension depend on the surfactant kind and its concentration. Stronger MF influence was found for the cationic surfactant and almost no changes were observed for nonionic Triton X‐100.

Anionic surfactant solutions under shear using dissipative particle dynamics.

We present a dissipative particle dynamics study of surfactant solutions under shear, which allows us to investigate their rheological properties. We consider a variety of concentrations and phase structures, including micellar solutions and liquid crystal phases. It is shown that the viscosity of micellar solutions increases as a function of concentration, in agreement with what is expected from experimental data. We also show that micelles can exhibit shear-thinning behavior when a shear force is applied, which is a result of micelles breaking down into smaller aggregates. Lamellar and hexagonal phases are found to orientate under the application of shear, in agreement with experimental observations. It is normally suggested that lamellar phases under shear can exhibit a transition between orientations as the shear rate is increased, usually as a result of lower viscosity. We calculate the viscosity for different lamellar phase orientations, showing that, although the viscosity of perpendicular orientations is lower than that of parallel orientations, we do not observe a transition to the perpendicular phase at high shear rates. Finally, we show that the choice of Schmidt number has a significant impact on the results, which is important for determining the correct behavior via simulations.

Regression modelling for concentration dependent mass density and specific volume of aqueous surfactant solutions

ABSTRACT. In the present work, mathematical models relating mass density and specific volume of solution with concentration for aqueous solutions of anionic (sodium lauryl sulfate - SLS) and cationic (cetyltrimethylammonium bromide - CTAB) surfactants (0-10% (w/w)) have been investigated. The experimental studies were performed to study the effect of solution concentration on mass density and specific volume of solution. Mass density increases, and specific volume decreases with an increase in solution concentration for both surfactants. Linear, quadratic, cubic, quartic, quintic, and exponential models were fitted to the experimental data to check the applicability. The models were validated based on the coefficient of determination (R2) and the sum of square of error (SSE) to be unity and zero, respectively. Modelling results reveal that the quintic model was fitted to study the effect of density on solution concentration for both surfactants.
 
 KEY WORDS: Density, Surfactant, Cetyltrimethylammonium bromide, Sodium lauryl sulfate, Modelling, Regression
 
 Bull. Chem. Soc. Ethiop. 2023, 37(4), 1047-1054. 
 DOI: https://dx.doi.org/10.4314/bcse.v37i4.19

Effect of Surfactants on Reverse Osmosis Membrane Performance

The aim of this study was to evaluate the performance of a reverse osmosis (RO) membrane in surfactant removal using various surfactant model aqueous solutions. The separation tests were performed with laboratory scale units in a dead-end configuration. Cellulose Acetate (CA) and Polyamide (PA) RO membranes were used with nonionic, anionic, or cationic surfactants at a wide range of concentrations. Membrane performance was evaluated using permeate flux and total organic carbon (TOC) rejection. The effects of surfactant type and concentration on RO membranes were assessed. Permeate flux of the PA membrane depended on the surfactant type and concentration. The separation of cationic surfactant aqueous solutions yielded the lowest permeate flux, followed by nonionic and anionic surfactant aqueous solutions, respectively. Surfactant adsorption on the membrane surface occurred at very low concentration of cationic and nonionic surfactants due to electrostatic and hydrophobic interactions, respectively, which affected permeate flux, and micelles did not affect the permeate flux of PA membrane. However, for CA membrane the permeate flux was not affected by the feed solution. Both membranes exhibited satisfactory TOC rejection (92–99%). This study highlights the importance of assessing interactions between membrane material and surfactant molecules to mitigate membrane fouling and guarantee a better performance of the RO membrane.

Structural Transitions of Anionic, Cationic, and Nonionic Surfactant Solutions Confined between Amorphous SiO2 Slabs: Molecular Dynamics Simulations

Adsorption of surfactants of a different nature on solid surfaces has found remarkable enthusiasm in many industrial processes such as enhanced oil recovery, detergency, solubilization, and flocculation/dispersion. Surfactants can interact with solid slabs and alter their surface charge and hydrophobicity, which are essential in interfacial phenomena. Interestingly, the surface charges of amorphous materials are thoroughly different from crystalline materials due to the disordered distribution of surface atoms. Therefore, we performed molecular dynamics simulations to examine the interactions of surfactant solutions with SiO2 surface in detail. To this aim, aqueous solutions of various surfactants were confined between two amorphous SiO2 walls, which were 10 nm apart. The results indicate that the structure of the amorphous solid surfaces is changed substantially due to their interactions with surfactant solutions. The simulation results indicate the presence of the nonionic surfactant aggregates in the bulk solvent, while ionic surfactants without branching, such as SDS, form aggregates that adsorb on the SiO2 surface. The interactions of the confined surfactants with glassy SiO2 slabs change the structure of the surface layer and consequently alter the surface charge density during the simulation, which leads to the separation of cationic and anionic parts of the confined surfactants in the vicinity of amorphous SiO2 slabs.

Highly Selective Methodology for Entrapment and Subsequent Removal of Cobalt (II) Ions under Optimized Conditions by Micellar-Enhanced Ultrafiltration

Micellar-enhanced ultrafiltration (MEUF), being a separation technique, was used to remove cobalt metal ion (Co2+) from their aqueous solutions in an application to reduce the toxicity level from industrial effluents using a micellar solution of anionic and cationic surfactants. The metal ions were first adsorbed by using anionic surfactants, i.e., sodium dodecyl sulfate (SDS) and sodium oleate (SO). The calculations for partition (Kx) and binding constants (Kb) and their respective free energy of partition and binding (ΔGp and ΔGb kJmol-1) helped significantly to find out the extent of binding or interaction of Co2+ with the surfactant and ΔGp and ΔGb were found to be -29.50 and -19.38 kJmol-1 for SDS and -23.95 and -12.67 kJmol-1 in the case of SO. MEUF work was also performed to find out the optimal conditions to remove metal pollutants from the aqueous system. For the said purpose, various factors and concentrations effect were studied, such as the concentration of the surfactant, concentration of the electrolyte (NaCl), transmembrane pressure, RPM, and pH. The efficiency of this process was checked by calculating various parameters, such as rejection percentage (R%) and permeate flux (J). A maximum rejection of 99.95% with SDS and 99.99% with SO was attained.

Revealed Properties of Various Self-Assemblies in Two Catanionic Surfactant Systems in Relation to Their Polarity and Molecular Packing State.

A catanionic surfactant system is an aqueous solution or dispersion of cationic and anionic surfactants that spontaneously self-assemble into structures such as micelles, vesicles, and coacervates. Their structural diversity varies depending on the ratios of cationic and anionic surfactants (compositions), the chemical structure of the constituent molecules, etc. Herein, two types of catanionic surfactant systems were systematically characterized: (i) cetyltrimethylammonium bromide (CTAB) and sodium dodecyl sulfate (SDS), both typical ionic surfactants; and (ii) dodecylmethylimidazolium ammonium bromide ([C12mim]Br) and SDS, where the former is an ionic liquid. By observing the sample appearance, turbidity, and particle size, the phase state of each system was analyzed according to the total concentration of surfactants and the molar ratio of cationic surfactants to the total concentration. Especially, for specific compositions of catanionic surfactant vesicles (cataniosome), the closed structure of the vesicles was confirmed through calcein entrapment and release detected with a fluorescence assay. The polarities of the interface of the prepared self-assemblies were evaluated using a fluorescence probe, Laurdan. The packing state of the molecules in the formed self-assembly structure was estimated using Raman spectroscopy. The results clearly indicate consistent phase-transition behavior for the CTAB-SDS (i) and [C12mim]Br-SDS (ii) systems, depending on the total surfactant concentration and composition, while the membrane properties of the two systems differed. The cataniosome formed in the CTAB-SDS system was in a tightly packed membrane state and more hydrophobic than that formed in the [C12mim]Br-SDS system owing to the difference in the structure of the constituting molecule: [C12mim]Br has a larger head group and shorter acyl chain than CTAB. The self-assembly properties evaluated in this study were compared with those of typical lipid membranes, liposomes (lipid vesicles), to determine a possible application of the catanionic systems with various self-assembly formulations.