Binary Surfactant Systems Research Articles

Choline chloride-Urea based deep eutectic Solvent: Characterization, interfacial behavior and Synergism in binary (surfactant) systems

The paper focusses on the synthesis and characterization of choline chloride: urea (molar ratio 1:2) DES. The influence of the varying DES concentration on the surface and interfacial behavior of low-concentration commercial surfactant (cetyl trimethyl ammonium bromide) was examined. The incorporation of DES into the surfactant solution resulted in an augmentation of electrophoretic mobility and absolute zeta potential values, indicative of enhanced surfactant adsorption at the interface. Sessile drop measurements demonstrated the capacity of binary mixture to modify the wettability of sandstone from intermediate-wet state to water-wet condition. In summary, physicochemical evaluation revealed the capability of DES to augment the self-assembly and wetting behavior of surfactant at low concentrations (below critical micelle concentration). The observed phenomenon in these solvents primarily finds utility in nanoscience, drug delivery systems, colloids, catalysis, and applications in many other fields.

A static and dynamic analysis of nonionic-based binary surfactant systems for adsorption mitigation in a carbonate reservoir with high salinity

Surfactants are crucial in chemical enhanced oil recovery, but high adsorption onto rocks reduces their efficiency and economic viability. Sacrificial agents, such as alkalis, nanoparticles, and polymers have been investigated to mitigate this issue but they in turn present drawbacks such as poor oil interaction, compatibility issues, pore plugging, and increased costs. Binary surfactant systems, due to their favorable potential synergistic interactions, are proposed as solutions for reducing surfactant adsorption. Static adsorption experiments were conducted to assess the effect of the binary surfactants on adsorption efficiency, and the impact of salinity on the adsorption process equilibrium was also studied. Five core flooding experiments under reservoir temperature (41∘C), reservoir pressure (21 MPa), and high salinity (23.4 wt.%) were conducted to evaluate dynamic adsorption. The surfactant concentrations in supernatant and effluent, after the adsorption process were determined via interfacial tension tests using a spinning drop method. The results showed a significant reduction in surfactant adsorption on carbonate rocks, from 9.99 mg/g-rock to 0.68 mg/g-rock for anionic surfactants and from 5.38 mg/g-rock to 0.19 mg/g-rock for zwitterionic surfactants, with corresponding dynamic reductions of 61% and 89%. Our results were further evidenced by the little to no changes in the differential pH curves in the adsorption process of the binary surfactant systems. This study presents a cost-effective approach for significantly reducing surfactant adsorption on carbonate rocks and aids in designing surfactant formulations for adsorption reduction in high-temperature, high-salinity carbonate reservoirs.

An experimental study of foam-oil interactions for nonionic-based binary surfactant systems under high salinity conditions

A key factor affecting foam stability is the interaction of foam with oil in the reservoir. This work investigates how different types of oil influence the stability of foams generated with binary surfactant systems under a high salinity condition. Foam was generated with binary surfactant systems, one composed of a zwitterionic and a nonionic surfactant, and the other composed of an anionic and a nonionic surfactant. Our results showed that the binary surfactant foams investigated are more tolerant under high salinity conditions and in the presence of oil. This was visually observed in our microscopic analysis and was further attributed to an increase in apparent viscosity achieved with binary surfactant systems, compared to single surfactant foams. To understand the influence of oil on foam stability, we performed a mechanistic study to investigate how these oils interact with foams generated with binary surfactants, focusing on their applicability under high salinity conditions. The generation and stability of foam are linked to the ability of the surfactant system to solubilize oil molecules. Oil droplets that solubilize in the micelles appear to destabilize the foam. However, oils with higher molecular weights are too large to be solubilized in the micelles, hence the molecules will have less ability to be transported out of the foam, so oil seems to stabilize the foam. Finally, we conducted a multivariate analysis to identify the parameters that influenced foam stability in different oil types, using the experimental data from our work. The results showed that the oil molecular weight, interfacial tension between the foaming liquid and the oil, and the spreading coefficient are the most important variables for explaining the variation in the data. By performing a partial least square regression, a linear model was developed based on these most important variables, which can be used to predict foam stability for subsequent experiments under the same conditions as our work.

Interaction Parameters for the Formation of Mixed Micelles and Partitioning of Solutes in Them: A Review

When two or more surfactants are mixed, the critical micelle concentration and solubilization capability are changed, and a careful selection of the combination promotes the micelle formation and enhances the solubilizing capability. Thus, understanding the mechanism behind the phenomena is essential for controlling the physical properties of the mixed micelle. The interaction parameters β and B that describe the formation of mixed micelles and their partitioning of solutes, respectively, were proposed by Treiner four decades ago. In this work, data on the formation and partitioning in binary surfactant systems were collected. Although the data on the parameters β and B for polar solutes and theoretical development are still insufficient, the directions of research to acquire an in-depth understanding of the formation and partitioning of the mixed micelle are proposed.

Nonylcyclohexanol polyethoxylate, a greener alternative of nonylphenol polyethoxylate endows sodium oleate solution high salt tolerance

Nonylphenol polyethoxylate (NPEOn) has been expected to enhance salt tolerance of system containing carboxylates, but banned in countries recently. Herein, a group of new surfactants, nonylcyclohexanol polyethoxylate (NCEOn) was formulated with sodium oleate (NaOA) into binary surfactant systems, to investigate their interaction towards salt tolerance, phase behavior, interface tension and lime soap dispersing requirement in brine with comparison of NPEO10. The results indicate that the salt tolerance of NaOA-NCEOn system increased with increasing NCEOn concentration and EO number, following the order towards the salts: SO42- > Cl- for anions and Na+ > Mg2+ > Ca2+ for cations, respectively. Moreover, cloud point (CP) of NaOA-NCEOn system was increased by adding NaOA but decreased by introducing inorganic salts, respectively. The influence strength of cationic ions on CP decline was in the order: Na+ < Mg2+ < Ca2+. The thermodynamic parameters at CP explains the difference in salt tolerance of NaOA towards monovalent and divalent cations. Notably, the NCEO11(0.02 %)-NaOA (0.05 %) system exhibited similar or superior salt-tolerance in NaCl (20 %) or CaCl2 (2 %) brine, as NPEO10 did. The solubility of NaOA in saline (0.1 %-5%) was up to thousand folds of that in water, suggesting NCEOn a green substitute for NPEO10 in the field.

Oscillations in Dynamic Surface Tension of Cationic-nonionic Binary Surfactant Aqueous Solutions.

In this work, the adsorption dynamics of mixed aqueous solutions of tetraethyleneglycol monoocthyl ether (C8E4) - dodecyltrimethylammonium bromide (DTAB) were studied using sessile bubble surface tensiometry. When C8E4 was added to the DTAB solution, the dynamic surface tension exhibited a unique oscillation decay pattern. In contrast, the addition of DTAB to the C8E4 solution resulted in a simple monotonic decay of the surface tension. The same trend was observed for mixtures of tetradecyltrimethylammonium bromide (TTAB) and DTAB. The occurrence of two distinguishable dynamic surface tension behaviors showed reasonable similarity with the theory of the adsorption kinetics of polymer solutions, where the surface tension oscillation was caused by the delayed desorption of polymers due to the conformational change at the solution surface. We compared the dynamic surface tension of binary surfactant systems and the polymer solution theory, and discussed the origin of surface tension oscillations based on the difference in the surface activity of the surfactants.

Analyzing the surfactant classification confusion through the HLD formulation equation

The qualitative presentation from Winsor on an interfacial balance of interactions between the surfactant and the oil and water phases has been transformed into a multivariable linear equation so-called hydrophilic-lipophilic deviation (HLD). This relation involves at least 6 independent variables (surfactant head and tail specifications, water salinity, oil nature, temperature, and pressure) with a MacLaurin series first order approximation, i.e., a linear multivariable expression. After 40 years of practical experience, it can be said that the HLD relation matches well the experimental data, with only very few exceptions with complex mixtures. Herein, we clear the confusion concerning the meaning and the mathematical handling of the surfactant parameter in the HLD equation. We start with a presentation of simple surfactant systems with only 4 parameters (water salinity, oil nature, surfactant nature, and temperature) as was done 40 years ago. Later, we present a critical discussion on the surfactant term, concerning binary surfactant systems, and on strategies for applications in ternary surfactant mixtures. We have found that the surfactant parameters can only be compared in a series of surfactants with the same head group, where the surfactant parameter is a linear function of the surfactant tail length.

Pluronic based neutral-ionic binary micellar surfactant systems for solubilizing the cationic methylene blue dye

The interaction of cationic methylene blue (MB) dye with binary micellar systems of non-ionic Pluronic®L-81 containing anionic sodium dodecyl sulfate (SDS) or cationic cetyl trimethyl ammonium bromide (CTAB) surfactants were probed through conductivity, uv-visible, FTIR, DLS, and zeta potential measurements with an objective to identify better solubilizing system at room temperature. The CMC of both SDS and CTAB was lowered in MB+L-81+SDS or CTAB systems. The absorption spectrum of MB showed a slight blue-shift with enhanced intensity upon increasing the concentration of anionic SDS and cationic CTAB, reflecting the strong electrostatic interaction and formation of micelles due to the solubilization of MB by L-81+SDS/CTAB systems. The higher negative value of ΔGm for L-81+SDS (-24.18 kJ/mol) than L-81+CTAB, (-17.07 kJ/mol) indicated better stability of MB in SDS system than CTAB. This could be attributed to the electrostatic attraction between dissimilarly charged MB (cationic) and SDS (anionic) in the ternary (MB+L-81+SDS) system and repulsive steric interaction between positively charged MB and CTAB. This was confirmed from micellar size analysis using dynamic light scattering (DLS) measurements and binding constant values. The estimated CMC values were comparable with the literature data. Hence, based on these results we propose that L-81+SDS binary system can be applied as a potential medium for removal of MB from the industrial effluents.

Novel approach for tuning micellar characteristics and rheology of a sulfate-free anionic surfactant sodium cocoyl glycinate

Amino acid based mild and sulfate-free anionic surfactant, sodium cocoyl glycinate (SCGLY) forms spherical micellar aggregates in water. The mixed micellar characteristics of SCGLY has been studied in the presence of nonionic surfactants like cocamide diethanolamine (CDEA) and lauryl glucoside (LG). The ternary aqueous system of SCGLY/CDEA/LG depicts higher surface activity and stronger aggregation ability compared to corresponding single or binary surfactant systems as revealed by tensiometry. The effect of pH (5.5–6.5) and total surfactant concentration (14–18 wt%) on thickening of SCGLY/CDEA/LG system is studied by rheology measurements. The presence of CDEA/LG amid charged SCGLY head group shrinks the electrostatic repulsion and induces sphere-to-rod micellar transition depicting low or moderate viscosity under as-prepared neutral pH. With alteration in pH, viscosity augmented to a maximum (at pH ~5.8) followed by a viscosity decrease. This is a novel finding for mild sulfate-free SCGLY surfactant solution which otherwise is very hard to thicken. Micellar size and charge is attained by dynamic light scattering, while micellar shapes and aggregation numbers are determined by small-angle neutron scattering (SANS) measurements. Moreover, foaming behavior (foamability and stability) and mildness property (zein solubility) of SCGLY can be optimized as per the necessity in the presence of CDEA and LG. This work might prove to be an innovative approach to tune the micellar characteristics and rheology of amino acid based surfactant formulation which could be extremely beneficial for cost-effective, thickener-free, sulfate-free surfactant systems used in cleansing composition with desired viscosity.

Marangoni spreading time evolution and synergism in binary surfactant mixtures

HypothesisMarangoni spreading driven by localized surfactant solution deposition previously has been studied only for single surfactant systems. For binary surfactant mixtures, interactions that generate surface tension synergism, a thermodynamic effect, may also synergistically enhance Marangoni spreading dynamics, introducing the concept of Marangoni synergism. Spreading dynamics and possible Marangoni synergism should depend not only on thermodynamic properties but also kinetic properties of the binary system. Experiments and modelingTracer experiments that capture post-deposition surfactant front motion were performed in parallel with computational modeling, using binary surfactant pairs with varying interaction strengths. The model coupled the Navier-Stokes and advective diffusion equations with a Frumkin-type binary adsorption model. FindingsWe confirm the existence of Marangoni synergism. Stronger binary surfactant attraction favors synergism in both surface tension reduction and Marangoni spreading. Binary composition ranges over which surface tension synergism occurs differ from those for Marangoni synergism, indicating that the origins of the two synergistic effects are not identical. Analysis of model spreading velocities show that the thermodynamic spreading parameter is the controlling factor at early times for both single and binary surfactant systems, while the intrinsic adsorption and desorption kinetics influence spreading velocities and thus the occurrence of Marangoni synergism at later times.

Effect of binary mixed-surfactants and hybrid nanofluid on spray cooling heat transfer

The present study emphasizes the spray-cooling enhancement of a copper heater block of 10 mm2 cross-sectional area with binary mixed surfactant based fluid and hybrid nanofluid using a pressure swirl nozzle with an orifice size of 0.51 mm. The experiments have been carried out at two distinct fluid input temperatures of 27 °C and 42 °C, with a volumetric flux of 3.50 cm3/cm2s. Polyvinyl pyrrolidone (polymer surfactant), Sodium dodecyl sulfate (an anionic surfactant), Tween-20 (a nonionic surfactant) have been used as binary mixed surfactant systems in distilled water. The best performance has been obtained with SDS:Tween-20, which resulted in a maximum heat flux of 264 W/cm2 and a heat transfer coefficient of 3.59 W/cm2K. When compared to distilled water, the heat transfer coefficient increased by 32.2%, but only by 25.2% and 18.1% with PVP:Tween-20 and SDS:PVP surfactant solutions. Further, the effect of a hybrid nanofluid, which is a colloidal mixture of Titanium dioxide (TiO2) and MWCNTs (multi-walled carbon nanotubes) in distilled water, has been studied to better understand spray cooling heat transfer enhancement. Heat transfer was first enhanced by the hybrid nanofluid and then decreased as the volume concentration was increased from 0.1% to 0.3%. A maximum heat flux of 234 W/cm2 and a heat transfer coefficient of 3.15 W/cm2K has been achieved, with a heat transfer coefficient improvement of nearly 27.3% compared to distilled water. However, the mixed surfactant system outperformed, giving nearly 12.8% improvement in heat flux values. It has been observed that low surface tension resulted in high heat transfer rates. Furthermore, the effect of 15 °C subcooling on heat transfer performance has been investigated. A new correlation to find Nusselt number is proposed in terms of Reynolds number, Weber number and Prandtl number with a mean absolute error of 7.16%.

Surface Properties of Alkyldi(oxyethylene) β-D-Maltoside

A series of nonionic disaccharide-based surfactants alkyldi(oxyethylene) β-d-maltosides (4a-4h, n = 6-16) were synthesized, and their physicochemical properties were further investigated. Six β-D-maltosides (4c-4h, n = 8-16) exhibited a fan-shaped texture feature, whereas hexyldi(oxyethylene) β-D-maltoside (4a) had the strongest hygroscopicity. Owing to the incorporation of the hydrophilic dioxyethyl spacer (-(OCH2CH2)2-), the related water solubility improved significantly. Tetradecyldi(oxyethylene) β-D-maltoside (4g) had good water solubility, whereas hexadecyldi(oxyethylene) β-D-maltoside (4h) had weak water solubility. Meanwhile, the surface tension of β-D-maltosides (4a-4g, n = 6-14) had a decreasing tendency with increasing the alkyl chain length, whereas 4g had the best surface activity. Furthermore, decyldi(oxyethylene) β-D-maltoside (4e) had the best foaming ability and foam stability. Dodecyldi(oxyethylene) β-D-maltoside (4f) had the best emulsifying property in the rapeseed oil/water system. In contrast, both ammonium dodecyl sulfate (NH4DS)/4f and cetyltrimethylammonium chloride (CTAC)/4f binary surfactant systems showed a synergistic effect in surface activity because the CCMC/CMCidmix was <1. NaCl impacted the surface activity of the aqueous 4f solution through salt-surfactant synergistic effects. The results showed that such surfactants should have potential applications in the related field in the future.

Playing Favorites: Preferential Adsorption of Nonionic over Anionic Surfactants at the Liquid/Liquid Interface.

While many studies have investigated synergic interactions between surfactants in mixed systems, understanding possible competitive behaviors between interfacial components of binary surfactant systems is necessary for the optimized efficacy of applications dependent on surface properties. Such is the focus of these studies in which the surface behavior of a binary surfactant mixture containing nonionic (Span-80) and anionic (AOT) components adsorbing to the oil/water interface was investigated with vibrational sum-frequency (VSF) spectroscopy and surface tensiometry experimental methods. Time-dependent spectroscopic studies reveal that while both nonionic and anionic surfactants initially adsorb to the interface, anionic surfactants desorb over time as the nonionic surfactant continues to adsorb. Concentration studies that vary the ratio of Span-80 to AOT in bulk solution show that the nonionic surfactant preferentially adsorbs to the oil/water interface over the anionic surfactant. These studies have important implications for applications in which mixed surfactant systems are used to alter interfacial properties, such as pharmaceuticals, industrial films, and environmental remediation.

Studying on the properties of Mixed Surfactant Systems

The Anionic-nonionic Gemini Surfactant oxalamide polyoxyethylene lauryl ether (7) succinate sodium sulfonate (OPLES-7) was synthesized. It was mixed with the dodecyl glucoside in different ratios to enhance application performance. The mixed critical micelle concentration (CMC) of the binary surfactant systems was determined by surface tension measurement. Critical micelle concentration of mixed system is 0.141mmol ⋅ L−1 when the molar fraction of OPLES-7 to dodecyl glucoside 1:1. The influence of NaCl on surface properties of the mixed system was also studied. The surface activity was enhanced with the increase of NaCl concentration.

Application of power law in conductivity of binary mixed rhamnolipid surfactant systems

The limiting molar conductivity (Λ0) reflects the dissociation and the interaction of the electrolyte, and for the surfactant, it also reflects the interface adsorption and aggregation behavior of the molecules. A commonly used calculation method of Λ0 is the extrapolation of conductivity. In this article, a new approach known as Power law were used to improve the accuracy of the determination of Λ0 comparing the Ostwald's dilution law. The Law of independent migration proposed by Kohlrausch was used to explain the ionization and aggregation of surfactants in extremely dilute solutions. The effect of additives (N-Butanol, Diethanolamine (DEA) and PEG400) on Rhamnolipid (RL) aqueous solution were studied by conductivity method. From the obtained conductive results, we can calculate the critical aggregation concentration (CAC), the counter ion dissociation degree (α), the Gibbs standard free energy of micellization (ΔGmic°), molar conductivity (Λ), and aggregation numbers (nagg). Henry's law coefficient (H) and surface tension (γ) were also tested. The result shows that the α calculated by Power law is in good agreement with obtained by the conductivity method, and the CAC, α, Λ0, γ, nagg and H had a good correlation.

Concentration-dependent physicochemical behaviors and micellar interactions in polyalkoxylated fatty alcohol-based binary surfactant systems

The concentration-dependent physicochemical behaviors of the binary mixtures of polyalkoxylated fatty alcohol (PAFA)-AS (alkyl sulfonate), PAFA-CB (cocamidopropyl betaine) and PAFA-APG (alkyl polyglucosides) and their micellar interactions were determined at the ratios of 9:1, 8:2, 7:3 and 6:4 (w/w). At concentrated level, the rheological study of all the PAFA-mixed surfactants display a Newtonian behavior at low viscosities. Prominent discrepancies among the mixed surfactant systems were observed after stepwise dilution of the samples. In tensiometry study, the types of mutual interaction in the mixed surfactant systems were evaluated by regular solution theory (RST). The CMCexp curves of PAFA-AS and PAFA-CB systems demonstrate lower position than their CMCtheo curves signifying that these nonionic–anionic and nonionic–zwitterionic samples behave nonideal showing synergistic interaction between individual components in the mixed micelles, as further verified by the negative values of interaction parameter β and activity coefficients f1 and f2 are less than 1. Meanwhile, the PAFA-APG system shows no significant mutual interaction between the nonionic–nonionic components in the mixed micelles. TEM micrographs depict the formations of branched wormlike micelles and multiconnected threadlike networks for the PAFA-AS and PAFA-CB systems, respectively, while gigantic multilamellar vesicles for the PAFA-APG system. Upon dilution of these mixed surfactants to CMC, the mixed micelles are in monodisperse sizes of less than 15 nm and in various magnitudes of zeta potential ranging from –2.92 to –21.87 mV.

Stabilization of foam using hydrophobic SiO2 nanoparticles and mixed anionic surfactant systems in the presence of oil

The use of nanoparticles has been intensively investigated to improve foam flooding in oil production. Because nanoparticles have larger adhesion energy at the air-water interface than the surfactant, they help to prevent a gas diffusion between bubbles that leads to foam film rupture. In this study, the detail investigation on the behavior of mixed-surfactant foam stabilized by silica nanoparticles (SiO2-NPs) was conducted. The binary surfactant systems of an internal olefin sulfonate (IOS) and sodium polyethylene glycol monohexadecyl ether sulfate (C32H66Na2O5S) were selected. The impact of alkane oil with varying carbon chain length (i.e. hexane, octane, dodecane, and hexadecane) was investigated. The findings from a similar system of foam in deionized water (DI) and brine solution also presented for comparison. For SiO2-NPs foam/brine system in the presence of oil, the foam stability increased to a maximum with respect to certainly added nanoparticles (10 ppm), and the additional surfactant is required to maintain the foam stability when the alkane chain length increases. The foam stability parameter indicated by spreading (S) and entering (E) coefficients shows that the SiO2-NPs foam systems with the shorter-tail surfactant (mixed C15-18 IOS) had lower the coefficient values compared to the longer-tail one (mixed C19-23 IOS), suggesting that the structure of surfactant influents on foam stability. The findings from this study bring an understanding of the SiO2-NPs foam/alkane oil behavior in the brine solution, which helps to select the appropriate system for improving foam flooding in EOR applications.

Micellar and Interfacial Behavior of Mixed Systems Containing Anionic-nonionic Gemini Surfactant

The Anionic-nonionic Gemini Surfactant oxalamide polyoxyethylene lauryl ether(9)succinate sodium sulfonate(OPLES-9) was synthesized. It was mixed with the anionic surfactant sodium lauryl sulfate(SDS) and the nonionic surfactant dodecanol polyoxyethylene(9) ether (AEO9) respectively in different ratios to enhance application performance. The experimental results showed that the surface performance of the mixed systems was more superior to the relevant single surfactants. The mixed critical micelle concentration (CMC) of the binary surfactant systems was determined by surface tension measurement. Critical micelle concentration of mixed system reached the minimum 0.146mmol·L−1 when the molar fraction of OPLES-9 to SDS was 1:1. Critical micelle concentration of OPLES-9/AEO9 mixed system reached the minimum 0.259mmol·L−1 when the molar fraction of OPLES-9 to AEO9 was 0.9:1.

Dilational Viscoelastic Properties of Water–Fuel Interfaces in Single and Binary Surfactant Systems

The interfacial rheology of a surfactant film surrounding a water-in-oil emulsion influences the stability of the emulsion significantly. In this research, we chose monoolein of molecular weight of...

Excess Gibbs energy of the binary mixed micelle formation between ionic and non-ionic surfactants in the set of: Sodium-cholate, sodium-deoxycholate, Brij S10 and Brij 58 at T = (283.15–323.15) K

Molar excess Gibbs energy of mixed micelle formation (ge) between ionic and non-ionic surfactants in the set of the following surfactants: sodium-cholate (SC), sodium-deoxycholate (SDC), Brij S10 (BS) and Brij 58 (B58) can be described by first order Margules function. The Regular Solution Theory (RST) hypothesis of zero excess entropy cannot be accepted with these systems of investigated surfactants. Molar excess entropy is probably the result of conformational entropy, while the configurational entropy is zero, and these two facts are the bases for the description of ge by first order Margules function. The interaction coefficient between the different building units of the investigated binary surfactant systems has greater value than 0, which means that there are antagonistic interactions between the surfactant molecules in the mixed micelles. According to the 1H-1H ROESY 2D spectra there are interactions between the hydrogens from the angular methyl groups of the SC (SDC) steroid skeleton and the hydrogen from the middle and terminal part of the B58 (BS10) hydrocarbon chain in the mixed micelles. The intensities of the cross-peaks and the interaction coefficients decrease with temperature, which suggests that with temperature increase the mixed micelle becomes more diffuse, i.e. less compact. There are cross-peaks in the ROESY 2D spectra between the building units of the mixed micelles, which mean that mixed micelles are formed, but the peaks don't give information about the synergistic or antagonistic effects between the surfactants.