Micellar and Interfacial Behavior of Cationic Benzalkonium Chloride and Nonionic Polyoxyethylene Alkyl Ether Based Mixed Surfactant Systems

Micellar and interfacial properties of mixed surfactant systems comprising benzalkonium chloride, a cationic surfactant and nonionic polyoxyethylene alkyl ether surfactants (POE: C₁₀E₇, C₁₀E₈, C₁₀E₉, C₁₀E₁₀) have been investigated by surface tension, fluorescence and dynamic light scattering techniques. Critical micelle concentration (CMC) for different mixing mole fractions has been investigated by surface tension and fluorescence measurements. Ideal CMC, mixed micellar composition (X ₁ ^m , X ₁ ^σ ), interaction parameters for mixed micelles (β ^m) and adsorption monolayer (β ^σ ), surface excess concentration (Г_max), minimum area per molecule (A _min) and related thermodynamic properties have also been determined. Lowering of the CMC and negative interaction parameter values indicate synergism in the mixed micelle and monolayer formed, whereas, thermodynamic parameters evaluated for the proposed mixed systems indicate stability of the resulting micelles and monolayer. Micellar aggregation number (N _agg) and hydrodynamic diameter (D _h) computed from fluorescence and dynamic light scattering measurements respectively illustrate micellar growth in the mixed state. Results obtained for the proposed mixed systems can be helpful in designing smart materials for industrial surfactant based formulations.     

Influence of Temperature on the Surface Tension of Triton Surfactant Solutions

The surface tension of different Triton surfactants (X-100, X-405, and X-705) with or without adding sodium chloride was measured in the temperature range between 20 and 40°C using the maximum bubble pressure method. Rising temperature reduced the surface tension of Triton surfactants via disrupting the H-bonds between the ethylene oxide (EO) group and water. Increasing the number of the EO groups created the steeper thermal gradient of the surface tension. The data indicated that EO-water bonds are easier to be broken by rising temperature than the water–water H-bonds, with an entropy change of −0.535 J deg⁻¹ per mole of EO. The presence of NaCl decreased the surface tension for all systems. However, NaCl produced a synergistic effect with surfactants on the surface tension.     

表面活性剂浓度对泡沫体系稳定性的影响

主要探讨了在泡沫体系内,表面活性剂对泡沫稳定性的影响,以表活剂浓度为主要研究点,总结了不同表活剂浓度下气泡的聚并过程,还分析了液膜的排液过程,指出界面流变学因素以及表活剂高浓度情况下的胶束分层现象是影响泡沫稳定的主要因素.表活剂浓度低于CMC时,界面流变学因素起主要决定作用;表活剂浓度高于CMC时,胶团分层起主要决定作用.     

Protocol for Studying Aqueous Foams Stabilized by Surfactant Mixtures

Even though foams have been the subject of intensive investigations over the last decades, many important questions related to their properties remain open. This concerns in particular foams which are stabilized by mixtures of surfactants. The present study deals with the fundamental question: which are the important parameters one needs to consider if one wants to characterize foams properly? We give an answer to this question by providing a measuring protocol which we apply to well‐known surfactant systems. The surfactants of choice are the two non‐ionic surfactants n‐dodecyl‐β‐d ‐maltoside (β‐C₁₂G₂) and hexaethyleneglycol monododecyl ether (C₁₂E₆) as well as their 1:1 mixture. Following the suggested protocol, we generated data which allow discussion of the influence of the surfactant structure and of the composition on the time evolution of the foam volume, the liquid fraction, the bubble size and the bubble size distribution. This paper shows that different foam properties can be assigned to different surfactant structures, which is the crucial point if one wants to tailor‐make surfactants for specific applications.     

Direct Method of Preparation of Dodecanesulfonamide Derivatives and Some Surface Properties

Alkanesulfonamide compounds are known as surfactants because of the presence of –SO₂NH– function in their molecule. Thus, they are used in many formulations in the chemical and textile industries and also as inhibitors of corrosion. Generally, sulfonamide derivatives are prepared using sulfonyl chlorides as the raw material. The methods often described in the literature involve the use of ammonia gas and pressure. A simple and direct method to prepare pure alkanesulfonamide derivatives possessing good surface properties is presented in this work. Thus, n-dodecanesulfonyl chlorides obtained by photochemical sulfochlorination of n-dodecane under visible light using sulfuryl chloride were separated from the reaction mixture. These sulfonyl chlorides, a mixture of primary and secondary isomers, were transformed in one step into N-ethyldodecanesulfonamides, N-ethanoldodecanesulfonamides and the salts of dodecanesulfonamidoacetic acid. After purification on chromatographic column, the six position isomers of these sulphonamide derivatives were analysed and well separated by gas phase chromatography using a nonpolar column. Then, gas phase chromatography analysis coupled to mass spectrometry using electronic impact (GC/MS/IE) was performed to identify the different position isomers. The primary isomers of sulphonamide derivatives were identified by crossed injection of the compounds obtained by synthesis from the 1-chlorododecane using the Grignard reagent, and identified by IR, ¹H- and ¹³C-RMN, elementary analysis and GC/MS/IE. Some physico-chemical properties of these sulphonamide derivatives were examined. The variation of surface tension versus the concentration of both primary and secondary sulphonamide derivatives were studied, and the critical micellar concentration was determined for the compounds showing surface activity. The foaming power was also determined by the Bartsch method, and the results obtained were compared to those of a commercial surfactant, the linear alkylbenzenesulfonate. The stability of the foam formed was also evaluated.

Influence of Hydrocarbon Chain Branching on Foam Properties of Olefin Sulfonate with FoamScan

The influence of surfactant structure on foam properties of internal olefin sulfonate (IOS) and alpha olefin sulfonate (AOS) in aqueous solutions was estimated from measurements of the foamability, foam stability, and foam morphology, as obtained from conductivity and image analyses techniques. It was found that the foamability and foam stability of C_16–18 AOS are higher compared to that of C_16–18 IOS, indicating that hydrocarbon chain branching decreases the foamability and foam stability. The foamability and foam stability are enhanced with increasing surfactant concentration, which increases the adsorbed quantity of surfactant molecules at the air–water interface. The influence of hydrocarbon chain branching on foam morphology was also investigated. It was found that foam cells produced by branched chain C_16–18 IOS are larger than the foam cells generated by straight chain C_16–18 AOS.     

Aqueous Foam Stabilized by Hydrophobic SiO2 Nanoparticles using Mixed Anionic Surfactant Systems under High-Salinity Brine Condition

A primary concern of surfactant-assisted foams in enhanced oil recovery (EOR) is the stability of the foams. In recent studies, foam stability has been successfully improved by the use of nanoparticles (NP). The adhesion energy of the NP is larger than the adsorbed surfactant molecules at the air–water interface, leading to a steric barrier to mitigate foam-film ruptures and liquid-foam coalescence. In this study, the partially hydrophobic SiO₂ nanoparticles (SiO₂-NP) were introduced to anionic mixed-surfactant systems to investigate their potential for improving the foamability and stability. An appropriate ratio of internal olefin sulfonate (C_15-18 IOS) and sodium polyethylene glycol monohexadecyl ether sulfate (C₃₂H₆₆Na₂O₅S) was selected to avoid the formation of undesirable effects such as precipitation and phase separation under high-salt conditions. The effects of the NP-stabilized foams were investigated through a static foam column experiment. The surface tension, zeta potential, bubble size, and bubble size distribution were observed. The stability of the static foam in a column test was evaluated by co-injecting the NP-surfactant mixture with air gas. The results indicate that the foam stability depends on the dispersion of NP in the bulk phase and at the water–air interface. A correlation was observed in the NP-stabilized foam that stability increased with increasing negative zeta potential values (−54.2 mv). This result also corresponds to the smallest bubble size (214 μm in diameter) and uniform size distribution pattern. The findings from this study provide insights into the viability of creating NP-surfactant interactions in surfactant-stabilized foams for oil field applications.     

An Alternative Approach for Determining Critical Micelle Concentration: Dispersion of Ink in Foam

The present work investigates the critical micelle concentration (CMC) of nonionic surfactant solutions using a new approach by monitoring the dirt dispersion (DD) defined as the amount of dirt absorbed by foam using India ink as a model dirt. DD has so far been studied qualitatively by eye estimation. Our quantification studies show that DD increases with increasing surfactant concentration and reaches a maximum. After this, it decreases and becomes very small. The concentration for which DD is maximum corresponds to the CMC, as determined from surface tension measurements. The CMC of natural surfactants obtained from plants Sapindus mukorossi, Albizia procera, Juglans regia, Zephyranthes carinata, and Acacia concinna was determined. The CMC obtained by DD are in reasonably good agreement with those obtained using the surface tension method. The DD method is easy, rapid, and inexpensive and can become an effective tool for estimating the CMC.     

Stability of foams containing proteins, fat particles and nonionic surfactants

The foamability of aqueous suspensions of proteins and fat particles containing different nonionic surfactants relevant to ice cream mix, through which air is continuously bubbled in a foam column, is investigated in terms of the growth of the foam until steady state is reached. Less water-soluble but more oil-soluble Spans 20, 80 and 85 (monolaurate, monooleate and trioleate of Sorbitan) reduced significantly the steady-state foam height and hence the foamability by enhancement of bubble coalescence. In contrast, highly water-soluble Tweens 20 and 80 increased only slightly the steady-state height of the foams as compared to that obtained using surfactant-free suspension. However, moderately water- and oil-soluble Tween 85 (polyoxyethylene sorbitan trioleate) decreased the foamability more significantly than the Spans. The bubbles are found to be small and coalesce relatively fast at the bulk air interface. The bridging of the fat particles by the three oleates could weaken the protein and fat network thereby reducing the elasticity of the air-aqueous phase interface. This is corroborated by the lowest interfacial elasticity measured using a biconical disc oscillatory rheometer. The stability of the foams formed is also determined by measuring the decrease in foam height and increase in mean bubble diameter with time after stopping the air flow. The results are found to verify a published theoretical model, which enabled to determine the parameters controlling foam stability. The Spans reduced the foam stability as the bubbles coalesced rapidly with bulk air. In contrast, the Tweens increased the foam stability as the bubbles coalesced very slowly. The increase of foam stability by Tween 85 under quiescent conditions is consistent with the measured high interfacial shear viscosity.     

Effect of Temperature on Foaming Ability and Foam Stability of Typical Surfactants Used for Foaming Agent

Foam has extensive applications in a wide range of industrial fields. Some surfactants are used as foaming agents in the preparation of foam. The performance of the foaming agent directly affects the application of the foam. In this paper, experiments were designed and conducted to reveal the influence of temperature on foaming performance of 10 typical anionic, cationic, nonionic, and amphiprotic surfactants. They were exposed to different temperature conditions to measure the foaming capacity (FC), foaming expansion (FE), and foam’s half-life. FC and FE represent foaming ability (FA), and half-life represents foam stability (FS). The results show that the FC increased at elevated foaming temperature, while FS decreased with rising temperature. Anionic surfactants are less affected by temperature and have better FA and longer FS. It seems that 20–30 °C is an ideal foaming temperature. This study lays an important foundation for the efficient preparation and utilization of foam in industrial fields.     

Synergistic Effects between Anionic and Sulfobetaine Surfactants for Stabilization of Foams Tolerant to Crude Oil in Foam Flooding

In foam flooding, foams stabilized by conventional surfactants are usually unstable in contacting with crude oil, which behaves as a strong defoaming agent. In this article, synergistic effects between different surfactants were utilized to improve foam stability against crude oil. Targeted to reservoir conditions of Daqing crude oil field, China (45 °C, salinity of 6778 mg L⁻¹, pH = 8–9), foams stabilized by typical anionic surfactants fatty alcohol polyoxyethylene ether sulfate (AES) and sodium dodecyl sulfate (SDS) show low composite foam index (200–500 L s) and low oil tolerance index (0.1–0.2). However, the foam stability can be significantly improved by mixing the anionic surfactant with a sulfobetaine surfactant, which behaves as a foam stabilizer increasing the half-life of foams, and those with longer alkyl chain behave better. As an example, by mixing AES and SDS with hexadecyl dimethyl hydroxypropyl sulfobetaine (C₁₆HSB) at a molar fraction of 0.2 (referring to total surfactant, not including water), the maximum composite foaming index and oil tolerance index can be increased to 3000/5000 L s and 1.0/4.0, respectively, at a total concentration between 3 and 5 mM. The attractive interaction between the different surfactants in a mixed monolayer as reflected by the negative β^s parameter is responsible for the enhancement of the foam stabilization, which resulted in lower interfacial tensions and therefore negative enter (E), spreading (S), and bridging (B) coefficients of the oil. The oil is then emulsified as tiny droplets dispersed in lamellae, giving very stable pseudoemulsion films inhibiting rupture of the bubble films. This made it possible to utilize typical conventional anionic surfactants as foaming agents in foam flooding.     

基于全氟丁基的氟表面活性剂的油水界面张力

研究以全氟丁基为基础的、在酸性环境中具有高表面活性的叔胺盐酸盐型阳离子氟表面活性剂C_4F_9SO_2NH(CH_2)_3NH(CH_3)_2+Cl~-(简称PFB-MC)的油水界面张力以及不同添加物的影响。通过界面张力测定,考察Na Cl、盐酸、正丁醇、异丁醇、正戊醇、正己醇,以及烷基三甲基氯化铵〔CnH_(2n+1)N(CH_3)_3Cl,n=12,16,18〕对PFB-MC水溶液-正庚烷界面张力的影响。分别测定PFB-MC与烷基磺酸钠CnH_(2n+1)SO_3Na(n=4,6,8)复配体系的表面张力及正庚烷-水界面张力,并与十二烷基苯磺酸钠(SDBS)复配的界面张力结果进行对比。结果表明,较高浓度的NaCl、盐酸、脂肪醇均能使体系的油水界面张力降低,但仅降低1~3 m N/m;烷基磺酸钠与PFB-MC表现出很好的协同性,体系的油水界面张力显著降低(降低4~9 m N/m),且界面张力随烷基磺酸钠碳链的增长而降低;而PFB-MC与SDBS复配由于溶解性的原因体系界面张力很高,其清液的界面张力为18.6m N/m。     

Experimental Investigation of the Mechanism of Foaming Agent Concentration Affecting Foam Stability

With the aim of determining the effect of foaming agent concentration (FAC) on foam stability, the half‐life of a selection of typical foaming agents was investigated at different concentrations using the FoamScan^® instrument. The surface tension of the bulk solution after foaming was tested using a surface tension meter. The FAC had a significant effect on foam stability at concentrations <1%, and a weak relationship at concentrations >1%. A significant turning point in the plot of foam stability versus FAC indicated maximum foam stability. The concentration at this point was defined as the optimal stability concentration, which is a guide in foam application. The micelles were thermodynamically unstable at low concentrations and degraded into surfactant solution, but were extremely stable at high surfactant concentrations that did not affect the stability of the foam. A turning point was also observed in the plot of surface tension versus FAC, beyond which the surface tension remained constant; the concentration at this point was defined as the no spherical micelle concentration. The influence of FAC on foam stability is explained in terms of mean bubble diameter (d_mb) and bubble size distribution.     

A Unified Survey of Applicability of Theories of Mixed Adsorbed Film and Mixed Micellization

Mixed micelles are an ever-interesting field in applied as well as academic research. An interesting problem is to determine the composition of the mixed monolayer and the micellar phase and interaction parameters among the individual components. Several theories have already been put forward to address these problems. In this work, we attempt to apply several theories to several experimental systems already published. Experimental elucidation of the proportion of individual components in such a mixed state of aggregation is impossible up till now to the best of our knowledge.

Asymmetric Three-Phase Surface Tension Forces in Agglomerating Particulate Systems

In accurate simulation of surface tension dominating systems, such as particulate systems in the nano- and mesoscale, the computation of interface curvature is essential. In a previous work a formulation using discrete differential geometry was demonstrated that could be used to find exact equilibrium solutions of surfaces. However, it was also shown that this formulation, as well all other tested formulations from those found in literature, fail to find accurate point-wise estimates for curvatures for particle-particle capillary liquid bridges. In this communication we elaborate on how total curvatures can be used for computing forces of parameterized models as well as in direct numerical simulations and demonstrate the infeasibility of using point-wise estimates on any asymmetric discretization. Near-exact numerical solutions are demonstrated for asymmetrically triangulated Catenoids and a minimal surface suitable for modeling liquid bridges between particles of different diameters.     

Surface Dilational Rheology,Foam, and Core Flow Properties of Alpha Olefin Sulfonate

The surface tension, surface dilational rheology, foaming and displacement flow properties of alpha olefin sulfonate (AOS) with inorganic salts were studied. The foam composite index (FCI), which reflects foaming capacity and foam stability, is used to evaluate foam properties. It is found that sodium and calcium salts can lead to decreases in AOS surface tension, critical micelle concentration, and molecular area at the gas–liquid interface. Sodium ions reduce the surface dilational viscoelasticity (E) and FCI of AOS, while calcium ions can enhance the E of AOS and make the FCI of AOS reach a maximum. In the solution containing calcium and sodium ions, the FCI of AOS is improved. Crude oil reduces the FCI of AOS. Injection pressure and displacing efficiency of AOS alternating carbon dioxide (CO₂) injection are higher than injections of water alternating with CO₂ or CO₂ alone in low permeability cores.     

Analysis of the Effects of Hydrocarbon Chain on Foam Properties of Alkyl Polyglycosides

The influence of surfactant structure on foam properties of different alkyl polyglycosides (APGs) in aqueous solutions was studied. Foamability, foam stability, and foam morphology were analyzed using the FoamScan method. Results showed that the foamability, foam stability, and the liquid carrying ability of long-chain APGs are higher than those of short-chain APGs. Foam morphology analysis showed that the foam produced by short-chain APGs is more unstable than the foam generated by long-chain APGs. Long-chain APGs have stronger intermolecular cohesion force, stringency, and ductility than short-chain APGs.     

Physicochemical Properties and Phase Behavior of Didecyldimethylammonium Chloride/Alkyl Polyglycoside Surfactant Mixtures

Mixed surfactant systems, used in many formulations, have aroused great attention and interest from researchers and industry due to the possibility of synergism. Alkyl polyglycoside (APG) and didecyldimethylammonium chloride (DDAC) mixtures combine the excellent properties of pure surfactants and play an important role in the development of multi‐functional washing products. To study the synergism between APG and DDAC, the physicochemical properties of different mixed systems have been investigated. The critical micelle concentration (CMC) is about 180 mg·L^?1 and the surface tension at the CMC is about 26.0 mN·m^?1 at a mass fraction of 40 % DDAC (ω_DDAC40 %). The values are significantly lower than pure surfactants. The foaming property shows the best performance at ω_DDAC20 %. When the mass fraction of DDAC is 80 %, the mixture exhibits better wetting and emulsifying properties. Synergism was observed in surface tension, foaming and emulsifying properties, while the wetting ability and detergency exhibited no such effects. Phase behavior of the APG/DDAC/water ternary system has also been carried out by polarized optical microscope. The phase diagram is characterized by a micellar phase, a region where lamellar and micellar phases coexist and a lamellar phase.     

Synthesis and Surface Tension Study of the Spacer Chain Length Effect on the Adsorption and Micellization Properties of a New Kind of Carboxylate Gemini Surfactant

A series of carboxylate gemini surfactants, which contain two hydrocarbon chains linked by amide groups, two carboxylate groups, a flexible alkane spacer were synthesized by three-step reactions and named alkylidene–bis-(N,N′-dodecyl-carboxypropylamides) (2C₁₂H₂₅CnAm; n = 2, 3, 4, 6, 8 is the number of methylene groups of the spacer), their structures were confirmed by FTIR,¹H NMR, and LC–MS/TOF, and their purity checked by HPLC. The micellar properties with increasing spacer chain length of these gemini surfactants were determined by surface tension methods. The critical micelle concentration (CMC) varies slightly with spacer chain length; surface tension at CMC(γ_CMC), the tendency of micellization versus adsorption, CMC/C₂₀, the minimum area per surfactant molecule at the air/solution interface (A_CMC), all decrease with increasing spacer chain length; surface reduction efficiency, pC₂₀, the surface excess at the air/solution interface (Г_CMC) increase with increasing spacer chain length. The results probably indicate that increasing spacer chain length of these carboxylate gemini surfactants will increase spacer incorporation into the double hydrophobic chain.     

Mixed Micelles of Trisiloxane Based Silicone and Hydrocarbon Surfactants Systems in Aqueous Media: Dilute Aqueous Solution Phase Diagrams, Surface Tension Isotherms, Dilute Solution Viscosities, Critical Micelle Concentrations and Application of Regular Solution Theory

Mixtures of trisiloxane type nonionic silicone surfactant (SS) with sodium dodecylsulfate, tetradecyltrimethylammonium bromide or tert-octylphenol ethoxylated with 9.5 ethylene oxide groups were studied in water at 30 °C by dilute aqueous solution phase diagrams, surface tension and dilute solution viscosity methods. The cloud points for the silicone surfactant aqueous solutions increased upon addition of hydrocarbon surfactants indicating the formation of hydrophilic complexes in mixture solutions. The scrutiny of the surface tension isotherms plotted as a function of SS concentration revealed that competitive adsorption effects are the characteristic features in these mixtures depending upon the SS concentration. Otherwise the isotherms exhibited two break points and the difference of concentration between the two break points increased with the increase in SS concentration indicating the cooperative nature of interactions. The micellar mole fractions of individual surfactants were determined by Rublingh's regular solution theory; interaction parameters and activity coefficients were evaluated and interpreted in terms of synergistic type interactions in these mixtures. The surface active parameters in mixture solutions were estimated and their analysis shows that the molecular species in the mixture solutions have a preferential tendency for adsorption at the air/water interface than in association form in the bulk solution. The effect of hydrocarbon surfactants on the intrinsic viscosity of SS micelles was monitored and related to the enhanced hydration in mixed micelles.