Interfacial Dilational Rheology of Sodium Lauryl Glycine and Mixtures with Conventional Surfactants

Amino acid-based surfactants are environmentally friendly surfactants, which have aroused increasing interest. In the application of amino acid-based surfactants, they are often compounded with other kinds of surfactants to obtain formulations that meet certain requirements. Herein, sodium lauroyl glycinate (C12-Gly-Na) was selected as a representative amino acid-based surfactant to compound with an anionic surfactant (sodium dodecyl sulfate [SDS]), a cationic surfactant (dodecyl trimethyl ammonium Bromide), and a nonionic surfactant (Triton X-100: p-octyl polyethylene glycol phenyl ether). Surface tension measurements and interfacial dilational rheological experiments were performed to study the interfacial behaviors of C12-Gly-Na and its mixtures. The results show that mixture systems have better interfacial activity than individual C12-Gly-Na and there is an obvious synergy between C12-Gly-Na and C12TAB under strong electrostatic attraction. Thus, the C12-Gly-Na/C12TAB mixture shows lower critical micelle concentration (CMC) and γ_CMC and higher dilational modulus than the individual surfactants. Besides, the film formed by the C12-Gly-Na/C12TAB mixture has higher viscoelasticity than single C12-Gly-Na and its mixtures with SDS and TX-100. With the increase of bulk concentration, the dilational moduli of C12-Gly-Na, C12-Gly-Na/SDS, and C12-Gly-Na/TX-100 run through two maxima, while, due to stronger electrostatic attraction, only one maximum appears in the C12-Gly-Na/C12TAB system. The study of the interfacial properties of amino acid surfactant and its mixtures with other surfactants provides a theoretical foundation for potential applications in cosmetic, food processing, and daily chemical industries.     

Interfacial Dynamic Properties and Dilational Rheology of Sulfonate Gemini Surfactant and its Mixtures with Quaternary Ammonium Bromides at the Air–Water Interface

The dynamic interfacial properties and dilational rheology of gemini sulfonate surfactant (SGS) and its mixtures with quaternary ammonium bromides (DTAB, CTAB) at the air–water interface were investigated using drop shape analysis. Results suggest that the adsorption process of these surfactants is diffusion-controlled at dilute concentrations, whereas the adsorption mechanism gradually shifts to a mixed kinetic-diffusion control with increasing surfactant concentration. The mixed surfactant system possesses the best surface activity when the molar ratios of SGS/DTAB and SGS/CTAB mixtures are 9:10. The formation of catanionic complexes shields the electrostatic repulsion between surfactant molecules and lowers the electrostatic adsorption barrier. Therefore, SGS/DTAB and SGS/CTAB mixtures exhibit higher adsorption rates than either component alone. The effects of oscillating frequency and surfactant concentration on the surface dilational properties of SGS, DTAB, CTAB, SGS/DTAB, and SGS/CTAB mixtures were also determined. As the oscillating frequency increases, the dilational elasticity of these surfactants gradually increases. The dilational elasticity peaks at a certain concentration, which is less than the critical micelle concentration (CMC). Results show that the dilational elasticity of SGS/DTAB and SGS/CTAB mixtures is higher than that of either component, resulting from the formation of a denser monomolecular adsorption layer at the air–water interface. Our study provides a basis for understanding the interaction mechanism of catanionic surfactant mixtures containing Gemini surfactant at the air–water interface.     

Adsorption and Aggregation Activity of Sodium Dodecyl Sulfate and Rhamnolipid Mixture

Measurements of the surface tension, density and viscosity of sodium dodecyl sulfate (SDS) and rhamnolipid (RL) mixtures were carried out in aqueous solution. From the obtained results, composition of mixed surface layer at the water–air interface, mixed micelles, parameter of intermolecular interactions, activity of SDS and RL in the surface layer and micelles, Gibbs standard free energy of adsorption and micellization as well as Gibbs free energy of SDS and RL mixing in the surface layer and micelles were established. These parameters were discussed in the light of independent adsorption of SDS and RL and the size of their molecules as well as the area in contact with water molecules. A correlation between the number of water molecules in contact with those of SDS and RL and standard free energy of adsorption as well as micellization of these surfactants was observed. A correlation between the apparent and partial molar volumes of RL and SDS in their mixture and size of surfactant molecules as well as the average distance between molecules was also found. The parameter of intermolecular interactions indicates that there is a synergetic effect in the reduction of water surface tension and micelle formation.     

气泡长大法测定表面活性剂溶液的表面扩展黏度

在理论分析的基础上 ,采用计算机图像采集技术 ,实时记录气泡的长大过程 ,用图像分析技术确定气泡边缘形状 ,建立了根据气泡图像测定表面扩展黏度的实验装置 .直接测量动表面张力随时间的变化 ,并通过动表面张力与气泡表面积变化率的关系 ,确定溶液的表面扩展黏度 .测定了十二烷基硫酸钠溶液的表面扩展黏度 ,并与不同表面变形速率下的文献值进行比较 ,说明了表面活性剂溶液的表面流变现象 .     

DIFFUSION AND ADSORPTION KINETICS OF A WATER-SOLUBLE NONIONIC SURFACTANT TO THE INTERFACE BETWEEN TWO VISCOUS IMMISCIBLE LIQUIDS

The kinetics of diffusion and adsorption of a water-soluble nonionic surfactant, polyoxyethylene sorbitan monolaurate (Tween-20), to the interface between two viscous immiscible liquids relevant to many applications is experimentally investigated using drop volume tensiometry. The measured variation in dynamic interfacial tension with contact time at different bulk concentrations of the surfactant in the viscous aqueous phase indicates that the equilibrium is slowly attained at low concentrations. As the bulk surfactant concentration is increased by two orders of magnitude, the contact time needed to reach equilibrium decreased by about an order of magnitude. The corresponding values of diffusion coefficient in the viscous liquid, determined using existing theoretical equations, are found to be almost constant. These are about two orders of magnitude smaller than those for the data available in literature for similar surfactants in much less viscous water at the air interface. The molecular area of Tween-20 determined in the present work is found to be very close to the value reported by other authors.     

DIFFUSION AND ADSORPTION KINETICS OF A WATER-SOLUBLE NONIONIC SURFACTANT TO THE INTERFACE BETWEEN TWO VISCOUS IMMISCIBLE LIQUIDS

The kinetics of diffusion and adsorption of a water-soluble nonionic surfactant, polyoxyethylene sorbitan monolaurate (Tween-20), to the interface between two viscous immiscible liquids relevant to many applications is experimentally investigated using drop volume tensiometry. The measured variation in dynamic interfacial tension with contact time at different bulk concentrations of the surfactant in the viscous aqueous phase indicates that the equilibrium is slowly attained at low concentrations. As the bulk surfactant concentration is increased by two orders of magnitude, the contact time needed to reach equilibrium decreased by about an order of magnitude. The corresponding values of diffusion coefficient in the viscous liquid, determined using existing theoretical equations, are found to be almost constant. These are about two orders of magnitude smaller than those for the data available in literature for similar surfactants in much less viscous water at the air interface. The molecular area of Tween-20 determined in the present work is found to be very close to the value reported by other authors.     

The Tail Effect of Some Prepared Cationic Surfactants on Silver Nanoparticle Preparation and Their Surface,Thermodynamic Parameters,and Antimicrobial Activity

The surface parameters of some cationic surfactants having different hydrophobic alkyl chains were assessed in aqueous solution using different techniques; surface tension, ultraviolet-Visible (UV–Vis) spectroscopy, and conductivity measurements. The obtained critical micelle concentration (CMC) for N-(2-((3,4-dimethoxybenzylidene)amino)ethyl)-N,N-dimethyloctan-1-aminium bromide (DBAO), N-(2-((3,4-dimethoxybenzylidene)amino)ethyl)-N,N-dimethyldodectan-1-aminium bromide (DBAD), and N-(2-((3,4-dimethoxybenzylidene)amino)ethyl)-N,N-dimethylhexadectan-1-aminium bromide (DBAH) in aqueous solution using three techniques are nearly the same. Increasing the hydrophobic chain length enhances micelle formation. Raising the solution temperature from 25 to 65 °C also shows the same trend. The thermodynamic calculations outlined the adsorption propensity of the surfactants at the surface compared to their affinity to form micelles. Both micellization and adsorption processes are enhanced with both the hydrocarbon elongation and with raising the solution temperature. The effect of the surfactant tail on the preparation process of the silver nanoparticles (AgNP) was assessed and confirmed using transmission electron microscope (TEM), dynamic light scattering (DLS), and UV–Vis spectra. Increasing the surfactant tail leads to a smaller particle size with a narrow distribution. The stability of the prepared AgNP is enhanced with hydrophobic surfactant tail elongation as proved with increasing the zeta-potential of the prepared AgNP colloid. The foaming power, interfacial tension, and emulsification stability of the DBAO, DBAD, and DBAH surfactants were determined. The DBAO, DBAD, and DBAH surfactants showed good antimicrobial activities against both bacteria (Gram positive and negative) and fungi, which have been enhanced because of incorporation of AgNP.     

Interfacial Tensions of Ethoxylated Fatty Acid Methyl Ester Solutions Against Crude Oil

The dynamic interfacial tension (IFT) of ethoxylated fatty acid methyl ester solutions against n‐alkanes, kerosene, and diluted heavy oil have been investigated by spinning drop interfacial tensiometry. The influences of ethylene oxide (EO) groups and alkyl chain length on IFT were investigated. The experiment results show that the water solubility decreases with an increase in alkyl chain length or a decrease in EO groups. The ability to lower the interfacial tension against hydrocarbons improves with both increasing alkyl chain length and EO group at the best hydrophilic‐lipophilic balance, which can be attributed to the enhancement of the interfacial hydrophobic interactions and the rearrangement of interfacial surfactant molecules. The mixed adsorption of surfactant molecules and surface‐active components may reduce IFT to a lower value. C₁₈=E₃ shows the best synergism with surface‐active components. However, the IFT values against pure crude oil are obviously higher than those against hydrocarbons, which may be caused by the nature of heavy oil.     

Dilational Properties of an Anionic Gemini Surfactant with a Hydrophobic Spacer

The dilational properties of the anionic gemini surfactant, ethanediyl‐1,2‐bis(sodium N‐decanoyl‐β‐alaninate), and the comparable conventional surfactant were investigated via the oscillation barrier technique. The oscillation frequency was varied between 0.0033 and 0.1 Hz. The dilational moduli of the gemini surfactant at low surfactant concentration show less dependence on the frequency at the air/water interface compared with the decane/water interface. The interface layer is basically elastic. The dilational moduli at the air/water interface are remarkably higher than those at the decane/water interface. The dilational moduli of the gemini surfactant show two maxima with increasing concentration, originating from the reorientation and compression of the surfactant molecules adsorbed at the interfaces. A possible schematic diagram of the adsorption of the gemini surfactant at the air/water and decane/water interfaces is proposed.     

Adsorption of nonionic surfactants at fluid-fluid interfaces: Importance in the coalescence of bubbles and drops

Major industrial applications of surfactants are related to the stability of emulsions and foams, which is directly dependent on the rate of coalescence of drops and bubbles. Surfactant molecules adsorb at the liquid-liquid and gas-liquid interfaces and prevent the drops and bubbles from coalescing with one another. Therefore, it is important to correlate the adsorption of surfactant with the time required for coalescence. In this work, we have studied the adsorption of three nonionic surfactants, Tween 20, Triton X-100 and Span 80 at air-water and water-toluene interfaces. The variation of surface and interfacial tension with the concentration of surfactant was studied and the data were fitted using a surface equation of state derived from the Langmuir adsorption isotherm. We have studied binary coalescence of water drops in toluene in presence of these three surfactants. Coalescence of air bubbles at flat air-water interface was studied in presence of the water-soluble surfactants, Tween 20 and Triton X-100. A stochastic model for coalescence was used to fit the coalescence time distributions. The significance of the model parameters was discussed.     

Dynamic surface tension and surface dilatational elasticity properties of mixed surfactant/protein systems

We present the study on dynamic surface tension and surface dilatational elasticity properties of dilute aqueous systems of pentaglycerol fatty acid esters (pentaglycerol monostearate, C18G5, and pentaglycerol monooleate, C18:1G5, whey protein, sodium caseinate, and mixed surfactant and protein at room temperature. The adsorption kinetics at the air-liquid interface has been studied by bubble pressure tensiometer and the oscillation bubble (rising drop) method. It has been shown that the dynamic surface tension curve basically presents two-regions; namely induction region and rapid fall region. During the induction time the adsorption is the diffusion-controlled process of amphiphilic surfactant or protein molecules from the bulk of the solution to the interface. Whey protein and sodium caseinate showed longer induction time approximately 10000 ms compared to the surfactant systems, where induction time was estimated to be approximately 1000 ms. However, in both the protein and surfactant systems, the induction time goes on decreasing with increasing the concentrations. The similar behavior was observed in the mixed system, and lower surface tension values were observed at higher concentrations. The fitting of the experimental data to the theoretical equation shows the presence of two relaxation mechanisms of widely different time scale for the adsorption of surfactant or protein molecules at the interface. The relaxation time strongly varies with the concentrations following the power law, and at fixed concentration it was the highest for whey protein and the lowest for C18:1G5 system. The surface dilatational elasticity determined within the frequency range of approximately 0.1 to 1 cycle/s supports the dynamic surface tension data.     

Surface Rheological Properties of Hydrophobically Modified Polyacrylamide and Imidazolium Surfactant Systems

The dilational rheological properties of hydrophobically modified polyacrylamide (HMPAM) or hydrolyzed polyacrylamide (HPAM) solutions without and with imidazolium surfactants ([C₁₄‐4‐C₁₄im]Br₂ and [C₁₄mim]Br) at the air/water surface were investigated using oscillating bubble measurements. The results obtained suggest that imidazolium surfactants interact with the polymer on the surface, enhancing the dilational viscoelasticity of surface film. The dilational modulus value of [C₁₄‐4‐C₁₄im]Br₂/HMPAM is higher than that of the [C₁₄mim]Br/HMPAM system at low polymer concentration, confirming that [C₁₄‐4‐C₁₄im]Br₂ with two head groups and two hydrophobic chains can combine with a polymer to form a strong film on the surface. Moreover, imidazolium surfactants have stronger hydrophobic interaction with HMPAM chains than those of HPAM, thus enhancing the surface film strength for a surfactant/HMPAM system. The surface interaction mechanism between polyacrylamide and imidazolium surfactant is proposed to result from the electrostatic interactions and the hydrophobic effect.     

New Interfacial Rheology Characteristics Measured Using a Spinning Drop Rheometer at the Optimum Formulation. Part 2. Surfactant–Oil–Water Systems with a High Volume of Middle-Phase Microemulsion

This article is a continuation of our first study on dilational interfacial rheology properties at optimum formulation for surfactant-oil–water systems at low surfactant concentration just above the cμc. Here, we have investigated a high content of middle-phase microemulsion with an optimum WIII phase behavior for a system containing sodium dodecyl sulfate, n-pentanol, and kerosene. A new oscillating spinning drop interfacial rheometer was used to measure the interfacial properties. The very low dilational elasticity moduli and phase angle found at or near hydrophilic–lipophilic deviation (HLD) = 0 are related to the presence of the bicontinuous phase microemulsion and to the fast surfactant exchanges between the bulk and the interface, regardless of the phases involved in the measurement using the spinning drop apparatus, i.e., the two-phase excess oil and excess water (O-W) or the bicontinuous microemulsion and excess water (M-W). We show that at or near optimum formulation, the interfacial tension and the dilational modulus for the M-W case almost instantly reach equilibrium, because of the high surfactant content in the microemulsion and the fast exchanges between the bulk and the interface. In contrast, when both excess phases (O-W) are measured, the changes in these properties are slower, due to the scarce presence of surfactants in both phases. The possibility of having almost all the surfactants trapped in the middle-phase bicontinuous microemulsion could explain the emulsion instability in all the WIII range. This is behaving as if there were no surfactant available in the oil and water phases to stabilize the oil or water droplets thus formed.     

Complexation of Surfactant/β‐Cyclodextrin to Inhibit Surfactant Adsorption onto Sand,Kaolin, and Shale for Applications in Enhanced Oil Recovery Processes. Part I: Static Adsorption Analysis

Surfactant adsorption onto solid surfaces is a major issue during surfactant flooding in enhanced oil recovery applications; it decreases the effectiveness of the chemical injection making the process uneconomical. Therefore, it was hypothesized that the adsorption of surfactant onto solid surfaces could be inhibited using a surfactant delivery system based on the complexation between the hydrophobic tail of anionic surfactants and β‐cyclodextrin (β‐CD). Proton nuclear magnetic resonance spectroscopy was used to confirm the complexation of sodium dodecyl sulfate (SDS)/β‐CD. Surface tension analysis was used to establish the stoichiometry of the complexation and the binding constant (K_a). Static adsorption testing was applied to determine the adsorption of surfactant onto different solids (sandstone, shale, and kaolinite). The release of the surfactant from the β‐CD cavity was qualitatively evaluated through bottle testing. The formation of the inclusion complex SDS/β‐CD with a 1:1 stoichiometry was confirmed. The K_a of the complexations increases as salinity and hardness concentration increases. The encapsulation of the surfactant into the β‐CD cavity decreases the adsorption of surfactant onto solid surfaces up to 79 %. Qualitative observations indicate that in the presence of solid adsorbents partially saturated with crude oil, the β‐CD cavity releases surfactant molecules, which migrate towards the oil–water interface.     

电解质溶液中表面活性剂控制吸附下液滴的速度

引　言Ｍａｒａｎｇｏｎｉ应力使液滴在充满表面活性剂的连续介质中运动比在洁净介质中运动慢得多 Ｄａｖｉｓ和Ａｃｒｉｖｏｓ[1]以及Ｓａｄｈａｌ和Ｊｏｈｎｓｏｎ[2 ]采用线性吸附模型从理论上研究了表面活性剂对液滴运动的影响 在假设活性剂不可溶且忽略其在液滴表面扩散的情况下 ,Ｋｉｍ[3]得到了受活性剂影响的液滴迁移速度的解析解 在考虑活性剂表面扩散的情况下 ,Ｋｉｍ[4 ]进一步研究了液滴的运动·陈晋南和Ｓｔｅｂｅ[5 ]采用非线性Ｌａｎｇｍｕｉｒ和Ｆｒｕｍｋｉｎ吸附模型 ,考虑了液滴与表面活性剂之间吸附单饱和及非理想相…     

Surface adsorption in the mixtures of sodium dodecylsulphate and oxyethylenated nonylphenol with different oxyethylenation degrees

The effectiveness of surface adsorption in an aqueous solution of mixtures of surfactants composed of an anionic surfactant, sodium dodecylsulphate, mixed with a nonionic one, polyoxyethylenated nonylphenol, was studied. Their behavior was compared separately. This surface adsorption was characterized by the values of the surface tension at 25°C of the total concentrations below, but near to the critical micelle concentration (CMC) in the mixtures mentioned. These were obtained as a function of different proportions of surfactants in the mixture and different chain lengths of nonionic polyoxyethylenated surfactant. The total surface excess concentrations of the surfactant mixtures and the average of molecular area per surfactant species at the aqueous solution/air interface were calculated. Finally, the values were analyzed vs the above parameters. Presented at the XDCth Meetings of CED/AID, Granada, Spain, March, 1988.     

The correlation of washability with the rate of surfactant adsorption

A relation between the rate of adsorption of surfactant molecules at a gas-liquid interface and the soil removal ability of the surfactant solution is presented. The relation is of the form SR=A+Bk+Ck² where SR is the percentage soil removed, A, B, and C are constants, and k is the first order rate constant for the adsorption process. The relation is empirical and as yet has not been coupled with a fundamental explanation of the detergency process on a molecular scale. The maximum soil removal does not always occur at the highest rate constant but may reach a maximum at an intermediate value. The soil removal process seems to be different above the CMC than below it. For the different surfactants studied, the soil removal is higher for the surfactant with larger rate constants. The rate of surfactant adsorption was obtained from dynamic surface tension measurements made with the oscillating jet technique. Soil removal information was obtained from laboratory tests using a Terg-O-Tometer and reflectance measurements on standard cloth swatches. Cationic, nonionic, and anionic surfactants were studied. Specifically, the surfactants were Triton X-100 (an octyl phenol with 8 or 9 ethylene oxide units), NaDBS (sodium dodecylbenzene sulfonate), and CTAB (cetyl trimethylammonium bromide). The surface tension time range of 5 to 60 milliseconds and soil removal ability of these surfactants was investigated over the temperature range of 20 to 60C, and the concentration range of 0.0003 to 0.009 M.     

Adsorption of surfactant during chemical enhanced oil recovery

Surfactant is extensively used as chemicals during chemical enhanced oil recovery (CEOR) process. Effectiveness of surfactant CEOR process depends on several parameters like formation of micro emulsion, ultra-low interfacial tension (IFT) and adsorption of surfactant. First two parameters enhance the effectiveness while the last parameter reduces the effectiveness. Micro emulsions are highly desirable for CEOR due to its low interfacial tension (IFT) value and higher viscosity. In this research the size of the emulsions were studied with particle size analyzer to study the liquid–liquid absorption process and the entrapment of oil drops inside surfactant drop. Initially, the average surfactant drop size was found to be 100 nm, after mixing the surfactant slug with reservoir crude, the size was increase up to 10 times. It signifies the formation of micro emulsion between surfactant and oil. Another attempt was done in this research to study the adsorption mechanism of surfactant on reservoir rock. The process of adsorption was studied by Langmuir and Freundlich isotherm to understand the adsorption phenomena. In this study, it was found that the adsorption follows Freundlich isotherm and the adsorption phenomena was chemical for surfactant flooding process. In chemical adsorption phenomena, the rate of adsorption is high because, surfactant molecules are adsorbed layer after layer by the rock surface. Use of alkali along with surfactant reduces adsorption of surfactant since, alkali blocked the active clay sites before interacting with surfactant and hence the adsorption isotherm was found to be Langmuir and phenomena was physical adsorption.     

Surface Properties and Solubility Enhancement of Anionic/Nonionic Surfactant Mixtures Based on Sulfonate Gemini Surfactants

As a class of novel surfactants, Gemini surfactants usually exhibit fairly excellent interfacial properties in aqueous solutions on account of the unique structure. They have significant application and development potential for industrial production. However, the mixing properties of Gemini surfactants with conventional surfactants are the key to their application. The equilibrium surface tension curves of anionic/nonionic surfactant mixtures based on the sulfonate Gemini surfactant (SGS-12) were measured using the Wilhelmy Plate method. The parameters of surface adsorption, the interaction parameters between anionic and nonionic surfactants, and the thermodynamic parameters of micelle formation were calculated from the corresponding equations. In addition, the dynamic surface tension (DST) curves of anionic/nonionic surfactant mixtures were examined through bubble profile analysis, and the diffusion performance parameters were acquired from empirical formulas. The solubilization of pyrene in micelle solutions was studied using UV–vis absorption spectroscopy. The results show that the interaction parameters of all anionic/nonionic surfactants are negative, indicating that there is a synergistic effect on reducing the surface tension. For the SGS-12/OP-10, SGS-12/Tween 80, SGS-12/AEO9, and SGS-12/APG0810 mixtures, the optimum mixing ratios are 6:4, 7:3, 7:3, and 8:2, respectively. The thermodynamic data of micelles show that the formation of mixed micelles for SGS-12/APG0810 mixtures is an enthalpy-driven process. The tendency of DST curves of the SGS-12/APG0810 mixture is similar to that of SGS-12. In comparison with single-surfactant solutions, the anionic/nonionic surfactant mixtures show stronger solubilization capacity toward pyrene.     

Correlation between adhesion of aqueous solutions of nonionic and anionic surfactant mixture with short-chain alcohols to polymer surface and their adsorption at interfaces. I. Adhesion tension and adsorption

Contact angle measurements of aqueous solutions of a p-(1,1,3,3-tetramethylbutyl) phenoxypoly(ethylene glycol) (Triton X-100)/sodium dodecylsulfate (SDDS) mixture with a short-chain alcohol (methanol, ethanol or propanol) on polytetrafluoroethylene (PTFE) and nylon-6 surfaces were made. Complete spreading of the studied solutions was observed only in the case of nylon-6. Contact angle isotherms were considered with regard to alcohol activity as well as the adsorption of the surfactant mixture and alcohol at the polymer-solution interface. For this analysis solid-liquid interfacial tension and changes of adhesion tension as a function of the surface tension of the solution were taken into account. It appeared that in the range of alcohol concentration in which it is present in the monomeric form in the bulk phase, the Gibbs surface excess concentration of the surfactant mixture and alcohol at the PTFE-solution interface is close to that at the solution-air interface. However, alcohol activity at these interfaces differ from each other. The adsorption of the surface active agents at the nylon-6-solution interface is much lower than at the solution-air interface.