Function Of Surfactant Concentration Research Articles

Effect of percentage of methanol on micellization position of mixed surfactant interaction in the absence and presence of dye

The interaction behavior of mixed surfactant-dye systems, i.e., anionic surfactant sodium dodecyl sulfate (SDS), cationic surfactant cetyl pyridinium chloride (CPC), and dye methyl orange (MO) was investigated through the allocation of micelles using conductivity measurements. Conductivity as a function of surfactant concentration was monitored to calculate the critical micelle concentration (CMC). The conductivity increased sharply as the surfactant content increased, according to the results. Moreover, the conductivity rises with temperature, whereas it falls with increased methanol (CH3OH). CH3OH-H2O mixed solvent media containing 0 %, 10 %, 20 %, and 30 % of CH3OH at 298.15, 308.15, and 318.15 K to work out the basic micelle fixation, gives significant understanding to the arrangement of the mixed surfactants. The CMC and degree of micellar dissociation (α) of SDS with CPC increase in the CH3OH and H2O mixture. The CMC and α values are increased by increasing the temperature. Various thermodynamic parameters, i.e. Standard free energy of micellization (ΔGmo), Standard enthalpy of micellization (ΔHmo), and Standard entropy of micellization (ΔSmo) were computed in SDS-CPC without MO. ΔGmo values for SDS-CPC in the presence of MO results in micellization more probable with MO.

Influence of High Surfactant Concentrations on the Morphology and Crystallinity of Electrodeposited Antimony and Bismuth Nanowires

Antimony and bismuth nanowires are excellent model systems to investigate the interplay of various size-dependent transport phenomena relevant for applications in thermoelectrics, spintronics, or catalysis. The properties of these nanowires can be significant influenced by size effects due to the large mean free path and Fermi wavelength of charge carriers and phonons. Since antimony and bismuth possess highly anisotropic Fermi surfaces, the transport is also strongly dependent on the crystallographic orientation. Therefore, it is very important to develop and control suitable electrodeposition processes that allow us to understand the nanowire growth and to accordingly adjust preferred orientation and morphology of the synthesized nanowires.The so called template route employed in the presented work allows to control number density, alignment, geometry, length and diameter of the nanowires. The electrolytes and plating processes influence crystallinity, crystal orientation, and morphology of the electrodeposited materials. Here, antimony and bismuth nanowires are grown by potentiostatic electrodeposition in polycarbonate etched ion-track membranes using SbCl3 and BiCl3 in aqueous electrolytes.In this talk, we will show the influence of the presence of nonionic and anionic surfactants in high concentrations in the electrolyte during the electrodeposition of Bi and Sb nanowires. The recorded current-time curves of the plating process will be presented. Systematic characterization of the nanowires by scanning- and transmission electron microscopy, and X-ray diffraction reveal a strong change in crystallinity as a function of surfactant concentration, which will be discussed in detail.

Effect of Anionic, Cationic, and Non-Ionic Surfactants on the Structural Stability and Morphology of Perfluorinated Sulfonic Acid Membranes

Redox flow batteries (RFB) are a critical technology for stationary grid-scale energy storage, with potential usage with intermittent power sources, such as wind and solar. RFBs are attractive for long-duration energy storage because the anolyte and catholyte are stored separately external to the electrochemical reactor, which allows the RFBs to be modular and stationary. Separating the electrolytes and the electrochemical cell decouples energy and power densities, unlike batteries that store charge in the solid-state, such as Li-ion, Pb-acid, or Ni-Cd. A standard RFB chemistry is the all-vanadium redox flow battery (VRFB), which utilizes the four oxidation states of vanadium, with V2+, V3+, V4+, and V5+. Recently, new electrolytes are being studied in energy storage devices. Such as the first redox flow battery to utilize microemulsions as the electrolyte.Microemulsions are a breakthrough electrolyte for energy storage (BEES) that is emerging as an alternative to traditional RFB electrolytes because they produce thermodynamically stable, homogeneous solutions of polar and non-polar molecules. The stabilization of oil and water solutions allows microemulsion electrolytes to accommodate organic redox species with fast electron transfer rates that are not soluble in the aqueous phase while still offering the high conductivity of an aqueous salt electrolyte. Microemulsions consist of two immiscible phases stabilized by a surfactant, a non-polar "oil" phase, solubilizing the redox material, and the polar phase, which typically consists of an aqueous brine that provides charge balance and conductivity. Additionally, if the redox molecule was a non-polar liquid, it could serve as the entire oil phase, maximizing the energy density. An attractive property of a microemulsion electrolyte is that each component can be environmentally and biologically safe. For example, the aqueous phase only contains salt and water, and surfactants are found in many household, personal, and food products. Furthermore, some redox materials investigated in our lab are vitamins such as menadione (vitamin K3) and tocopherol (vitamin E).This talk describes the structural, mechanical, and morphological studies of surfactants' effects on perfluorinated sulfonic acid membranes. Small-angle X-ray scattering monitored the morphological changes as a function of surfactant concentration and soaking time, revealing how the surfactant penetrated and altered the polymer membrane. FTIR and NMR spectroscopy are also employed, providing insight into any polymer membrane degradation or dissolution. We demonstrate that surfactant choice is not only crucial to the stability of the microemulsion used as an electrolyte but can ultimately destroy the separator in a redox flow battery.This work was supported as part of the Breakthrough Electrolytes for Energy Storage and Systems (BEES2), an Energy Frontier Research Center funded by the U.S. Department of Energy, Office of Science, Basic Energy Sciences under Award # DE-SC0019409.

Surfactant-influenced oil–water slip and flow in nanochannels studied by molecular dynamics and theoretical modeling

This work uses molecular dynamics (MD) methods to investigate oil–water two-phase flow in hydrophilic nanochannels with surfactants adsorbed at the oil–water interface. We reveal two new discontinuous effects of nanoscale fluid flow: (i) the velocity distribution in the water layer is not a univariate function of the pressure gradient, and (ii) the apparent viscosity in the oil–water interface region is a function of surfactant concentration and pressure gradient. Based on the MD results, a layered theoretical model describing the discontinuous effects at the nanoscale is developed. The theoretical model provides quantitative two-dimensional functions for oil–water interface slip and fluid mass flux with pressure gradient and surfactant concentration. Surfactants significantly inhibit oil–water slip and reduce fluid mass flux. This study thus provides important insights into the theoretical and numerical models for shale or tight oil production predictions.

Effect of surfactants and interfacial rheology on equilibrium drop size in turbulent liquid-liquid dispersions

Surfactants are often required to stabilize liquid-liquid dispersions produced by high shear mixers. Due to the high power input, drops are deformed rapidly in the dispersion zone so the dynamic interfacial properties governed by the surfactant adsorption rate can have a significant impact on the resulting drop size. The objective of this work is to develop a fundamental link between surfactant adsorption dynamics, interfacial properties, and turbulent emulsification processes. To ensure constant bulk surfactant concentration during dispersion, equilibrium drop size for dilute dispersions produced by a batch rotor-stator mixer were studied. Silicone oils of various viscosity were dispersed in aqueous nonionic surfactant solutions. Drop size distributions (DSD) were measured via a video microscopy/automated image analysis technique. Equilibrium interfacial tension was measured via a pendant drop technique, as a function of surfactant concentration. The dynamic surface tension was similarly measured. The data were fit to the Langmuir adsorption isotherm and the long-times approximation to the Ward – Tordai equation and the adsorption parameters and surfactant diffusivities so obtained were employed, with an estimate of the drop deformation timescale, to estimate the surface dilational modulus (Esd) or Marangoni stress acting on the drop’ surface due to interfacial tension gradients. Trends observed in the measured equilibrium mean drop size and DSD are explained in terms of the interfacial and rheological properties. Below the CMC, Esd peaks and the drop size increases with bulk surfactant concentration, despite a decrease in equilibrium interfacial tension. Above the CMC, Marangoni stresses are small but the presence of the surfactant still modifies the rheology of the interface, increasing the effective viscosity of the drops. A comprehensive set of mechanistic models for drop size in turbulent flows, based on Kolmogorov-Hinze theory, was developed and modified to partially account for the effect of surfactants via an appropriately defined effective viscosity. The approach allows integration of surfactant phenomena into widely accepted correlations for drop size in surfactant free systems.

The importance of angular bending of Gemini surfactants on their encapsulation efficiency

The self–assembly of nonionic X-shaped Gemini surfactants is studied here, with the purpose of determining their encapsulation efficiency. Using the coarse-grained simulation method called dissipative particle dynamics, we perform a set of simulations of ternary water/oil/surfactant systems, fixing the oil/surfactant ratio at 1:1. Two surfactant structures are modeled and their efficiency to encapsulate monomeric oil is measured as a function of surfactant concentration. It is found that the encapsulation efficiency is better when the X-shaped surfactant has a more “stretched” structure. Additionally, it is shown that the number of oil/surfactant aggregates formed by surfactants with a relatively “open” structure is less stable as a function of the surfactant concentration. This is in contrast to the surfactants with the stretched structure, which makes the aggregates formed a better alternative as oil trappers. These results should be useful when synthesizing X-shaped Gemini surfactants for their use as thickening agents or drug carriers.

Impact of carbonate mineral heterogeneity on wettability alteration potential of surfactants

Surfactants have been widely used for enhanced oil recovery. However, the wettability alteration potential of surfactants as a function of carbonate rock mineralogy remains broadly unclear. Thus, here we investigate the effect of cationic surfactant cetyltrimethylammonium ammonium bromide (CTAB) and anionic surfactant sodium dodecyl benzene sulphonate (SDBS) surfactant on three carbonate rocks and a pure calcite mineral sample under a range of concentrations. Contact angles were measured on all these samples as a function of surfactant concentration. Furthermore, at the critical micelle concentration, advancing and receding contact angles are also measured as a function of pressure (0.1 – 20 MPa) and temperature (303 – 323 K) to reflect the behavior under subsurface conditions. To understand the interactions at the surfactant-mineral interface and its associated impact on wettability alteration, the zeta potential of surfactant-brine-rock emulsions are measured while surface chemical groups are identified by Fourier-transform infrared (FTIR) spectroscopy. The results are further supplemented by Energy-dispersive X-ray spectroscopy (EDX), X-ray diffraction analysis (XRD), and thin section analysis while the surface properties are evaluated by Atomic Force Microscopy (AFM), and Scanning Electron Microscopy (SEM) techniques. The results indicate a notable wettability alteration potential for CTAB turning the calcite surface water-wet while increasing the surfactant concentration did not necessarily yield better wettability alteration. The wettability alteration potential of CTAB is found to correlate with the calcite content of the carbonate sample i.e., a higher calcite content led to a greater reduction in contact angle. Contact angles demonstrate a slight increase with increasing pressure, while they decreased with increasing temperature. Finally, the existence of CO group (carboxylate groups) tends to make the CTAB-treated surface more hydrophilic while the surfaces treated with SDBS did not reveal any notable trend with respect to CO group. The results of this study add to our understanding of the surfactant potential for wettability alteration of carbonate and thus have implications for chemical enhanced oil recovery.

A methodology for measuring the characteristic curvature of technical-grade ethoxylated nonionic surfactants: the effects of concentration and dilution

Abstract Characterization of the behaviour of commercially available non-ionic surfactants has received considerable attention due to their efficacy in a variety of applications. The main challenge in the application of these types of surfactants is that the hydrophilicity of the surfactant varies with concentration and dilution due to the polydispersity of the ethylene oxide groups. The hydrophilicity of a surfactant can be quantified by the characteristic curvature (Cc) parameter of the hydrophilic–lipophilic difference (HLD) framework. In this work, a model based on natural logarithmic regression was developed to calculate the Cc value of commercial surfactants as a function of surfactant concentration by a fast and simple phase scan. The slope of the Cc curve and the measured Cc at a reference concentration were used to develop the model. The Cc values determined with the model agreed with the measured values from the phase scans. Furthermore, the linear mixing rule proved to be reliable for mixtures of polydisperse ethoxylated surfactants. Finally, the impact of the water-to-oil ratio on the Cc was evaluated and the implications were discussed.

Effect of 1,2-propanediol on the Critical Micelle Concentration of Decyltrimethylammonium Bromide at Temperatures from 293.15 K to 308.15 K.

It is well known that polar organic compounds, such as alcohols and polyols, exert an appreciable influence on water structure and thus have important effects on surfactant micellization. These substances are often used to modify the properties of surfactants in aqueous solutions, increasing the practical applications they have in diverse industries. In this work, the critical micelle concentration (CMC) of decyltrimethylammonium bromide (C10TAB) in water and in 1,2-propanediol aqueous solutions was determined from both sound velocity and surface tension measurements as a function of surfactant concentration in the temperature range of (293.15 to 308.15) K. The critical micelle concentration of the surfactant increases as the concentration of 1,2-propanediol becomes higher, while the effect on temperature does not show important changes within the range considered. At the selected temperatures, the standard thermodynamic parameters of micellization suggests that the addition of 1,2-propanediol makes the micellization process less favorable. Thermodynamic analysis suggests that the micelle formation of C10TAB is an entropy-driven process at the temperatures considered in this study.

Influences of short-chain alcohols, urea and temperature on aggregation behaviour of tetradecyltrimethylammonium bromide and antidiabetic drug mixture

In this investigation, the supramolecular interaction between a surfactant- tetradecyltrimethylammonium bromide (TTAB) and an antidiabetic drug metformin hydrochloride (MNH) was studied in the presence of some additives (alcohols/urea). The conductometric analysis as a function of surfactant concentration was used to assess the critical micelle concentration (CMC) of TTAB + MNH mixed system. The effect of a gradual change of temperature on CMC within a certain range (298.15–318.15 K) was monitored to assess the thermodynamic nature of micellisation process. In addition, estimation of thermodynamic parameters (, , and ) and the determination of the degree of counter ion binding (β) give insight into the relative viability of a micellisation process. The values of were negative in all the mixed solvents studied and this was dependent on the chain length of the used alcohols. The thermodynamic parameters of transfer for shifting the micelles from aq. medium to aq. alcohols media and enthalpy-entropy compensation were also computed, compared with literature values and discussed with appropriate reasoning. Several supramolecular forces, including H-bonds, dipole–dipole, ion-dipole, hydrophobic, and electrostatic interactions, were recommended for the aggregation of the TTAB + MNH system.

Ionic Liquid/Non-Ionic Surfactant Mixtures As Versatile, Non-Volatile Electrolytes: Double-Layer Capacitance and Conductivity

Self-assembly of ionic liquids (ILs) on 2D materials such as graphene oxide and MXenes facilitated by non-ionic surfactants is a promising approach being increasingly used for the fabrication of high surface area electrodes resulting in high performance supercapacitors. However, the impact that non-ionic surfactants have on double-layer formation and ionic conductivity has yet to be explored. These surfactants are not ionically conductive, have low dielectric constants and high viscosity which are expected to impact the final performance of the electrode. In this study we analyze the effect of adding two commonly used non-ionic surfactants, P123 and Triton X-100 (TX-100) to 1-ethyl-3-methylimidazolium bis(trifluoromethylsulfonyl)imide (EMImTFSI) on the double-layer capacitance formed at a glassy carbon electrode by means of electrochemical impedance spectroscopy. The results, surprisingly suggest an improvement of 75% and 116% in the double layer capacitance measured at the open circuit voltage for 40% of P123 and TX-100, respectively. We also interpret the changes in the DC potential dependence of the capacitance via the most up-to-date understanding of double-layer charging mechanisms with ionic liquids. Similar to previous literature on solvent-based diluents such as polycarbonate and acetonitrile, which cause a similar effect, the improved capacitance is attributed to the reduced Debye length resulting from an increased effective ionic charge accrued by the IL when surrounded by the low-dielectric constant surfactant.Both electrolyte series show the same reduction in ionic conductivity (from 8.5 mS/cm to 1 mS/cm) with respect to concentration regardless of the higher viscosity measured for the P123 electrolyte series. Pulsed field gradient nuclear magnetic resonance, is used to determine the diffusion coefficient for the IL as a function of surfactant concentration and allow us to calculate the effective Stokes radius which is found to shrink significantly as a function of surfactant concentration. Similar to the improved capacitance, this is caused by a reduction in ion-ion interactions and an increase in the average effective charge on each ion. These effects make the electrolyte less sensitive than expected to the increased viscosity caused by addition of the more viscous surfactant phase.The ability to improve the capacitance with non-volatile, low dielectric constant additives, without significantly sacrificing ionic conductivity, opens up an improved avenue for completely non-volatile, non-flammable electrolyte design.

Performance of CO2 Foam Huff and Puff in Tight Oil Reservoirs

The challenges associated with unconventional reservoirs are related to their intrinsic nature: extremely low porosity and permeability. Combinations of horizontal wells and multistage hydraulic fracturing techniques have been developed to overcome the production obstacles and unlock the vast amount of oil in place in such formations. However, oil production still exhibits a sharp decline within the first 2 years after the stimulation, leading to an oil recovery of less than 15%. Thus, enhanced oil recovery methods need to be investigated to further increase the production rates and the recovery. In this study, laboratory experiments and numerical simulations were conducted to evaluate the performance of the CO2 foam huff and puff process and its impacts on oil recovery in tight oil formations. More specifically, the foam half-life was measured as a function of surfactant concentration and followed by the foam drainage ratio and its rheological properties in the subsequent tests. Reservoir simulations were conducted using the lab data and the field data collected from Cardium formation. Sensitivity analyses were finally carried out to investigate the effects of controlling variables on the CO2 foam performance. Experimental results revealed that the optimal surfactant concentration was found to be 0.2%, which is the critical micelle concentration point. Simulation results show that CO2 foam huff and puff can increase the oil recovery by more than 11% compared to that of the primary production. Moreover, sensitivity analyses show that the production time, injection time, and soaking time are the main effecting parameters, while the injection rate and the incremental injection rate are less important.

Drops spreading on fluid surfaces: Transition from Laplace to Marangoni regime

Oil drops placed on surfactant laden water surface exhibit a transition from surface tension driven to surface tension gradient driven spreading as a function of surfactant concentration. Interestingly, this transition occurs at the critical micellar concentration irrespective of surfactant chemistry demonstrating a connection between fluid flows and shuttling of surfactant between the bulk and the interface.

Effect of surfactant concentration on the hydrophobicity of polydisperse alkyl ethoxylates

AbstractThe effect of ethylene oxide number (EON) polydispersity on the phase behavior of alkyl ethoxylates has been well documented in the surfactant literature. These previous studies show that polydisperse alkyl ethoxylates appear more hydrophilic as the surfactant concentration decreases or as the oil‐to‐water ratio increases. This becomes a troubling issue considering that most surfactant formulations undergo dilution during use, and they experience a wide range of water‐to‐oil volume ratios. Within the hydrophilic–lipophilic difference framework, the surfactant hydrophobicity is assessed via the sigma (σ) term (also known as the characteristic curvature or Cc). In this work, the effect of surfactant concentration on the apparent value of sigma (σapp) is evaluated as a function of surfactant concentration. The experimental observations are then explained using a bifunctional model for alkyl ethoxylates that consider the dual nature of polar oils (free alcohol and low EON ethoxymers) as surfactants and as oil components. A segregation‐based model and a partition‐based model are implemented to account for the distribution of the ethoxymers in the surfactant pseudophase and the oil phase. Combining these distribution models with the bifunctional model and a group contribution model for sigma, one can predict the σ term versus surfactant concentration for a given water/oil ratio, starting from the EON distribution of the surfactant. The practical applications of the model are discussed.

Pinch-off of a surfactant-covered jet

Abstract

Eureka Moment: An Archimedean Alternative for the Determination of cmc of Surfactants via Weight Measurements.

Critical micelle concentration (cmc) is a key parameter of generally used surfactants, and many experimental techniques like tensiometry, conductivity, spectrophotometry, fluorometry, etc. for its determination have been reported. However, these contemporary methods for cmc determination are tedious, are time-consuming, are sensitive, and require sophisticated instrumentation. Herein, we demonstrate that the cmc of the surfactants can be estimated via monitoring the variation in the apparent weight of a density bottle floating in a surfactant solution as a function of surfactant concentration. The proposed method requires the use of a simple weighing balance; a cost-affordable instrument always available in scientific laboratories. The proposed method is simple to execute and does not require any complicated data analysis procedures. As an experimental proof attached to the claim, we demonstrate the estimation of the cmcs of all types of surfactants, viz., anionic, cationic, and nonionic, through the formulated method. The results obtained in terms of cmc values of the chosen surfactants closely match those reported through the use of different standardized protocols. The formulated experimental protocol is desirable in terms of the simplicity of the protocol, accuracy, and reproducibility of the results, and cost and accessibility of the required instrument. All these attributes of the presented protocol qualify it as an appropriate substitute to the modern techniques commonly used for the cmc determination.

Volumetric, acoustic, electrochemical and spectroscopic investigation of norfloxacin–ionic surfactant interactions

Rising levels of bacterial resistance to antibiotics is a persistent and dynamic concern in the field of medicine and demand design and discovery of new and more effective antibiotics. One of the major hurdles in designing new antibiotics which should be capable of passively diffusing across biological membranes is the scarcity of knowledge regarding their biophysical interaction with these membranes. Surfactant systems have been frequently reported in the past decade as potential pseudo-membrane models to understand biophysical interactions of drugs with biological membranes at the molecular level. The present work is aimed at understanding the interaction of norfloxacin (NRF), a fluoroquinolone drug, with dodecyltrimethylammonium bromide (DTAB, a cationic surfactant) and sodium dodecyl sulfate (SDS, an anionic surfactant) at molecular level. Volumetric and acoustic studies of DTAB and SDS in buffered solutions of NRF at physiological pH (7.4) and a temperature range of 298.15 to 313.15 K were performed to calculate apparent molar volume (ɸV), isentropic compressibility (Ks), apparent molar isentropic compressibility (ɸK), partial molar volume (ɸVo), partial molar expansibility (ɸEo), specific acoustic impedance (Z), relative association (RA), intermolecular free length (Lf) and sound velocity number (U). The variation in these quantities as a function of surfactant concentration is interpreted in terms of NRF-ionic surfactant interaction using a cosphere overlap model. Cyclic voltammetry and UV–visible spectroscopy were used to calculate the partition coefficient (Kc) and binding constant (Kb) of NRF with ionic micelles. Free energies calculated from corresponding Kc and Kb values revealed the spontaneity of partitioning and binding of NRF with ionic micelles.

Effects of Surface Viscosity on Breakup of Viscous Threads.

In addition to surface tension lowering and Marangoni stresses, surfactants also induce surface rheological effects when they deform against themselves at fluid interfaces. Because surface viscosities are functions of surfactant concentration, surface rheological stresses can compete with capillary, Marangoni, and bulk stresses in surfactant-laden free surface flows with breakup. To elucidate the effects of surface rheology, we examine the breakup of a Stokes thread covered with a monolayer of insoluble surfactant when either surfactants are convected away from the space-time singularity or diffusion is dominant. Surprisingly, in both limits, surface rheological effects always enter the dominant balance of forces and alter the thread's thinning rate. Moreover, if surfactants are convected away from the singularity, we provide an analytical expression for thinning rate that explicitly depends on surface rheological parameters, providing a simple route for measuring surface viscosity.

Critical Synergistic Concentration of Binary Surfactant Mixtures

This paper presents a simple method for determination of synergism in binary surfactant mixtures. A homologous series of cationic alkyltrimethylammonium bromides (CnTAB, with n = 8, 12, 16, 18) mixed with three non-ionic surfactants (n-octanol, methyl isobutyl carbinol, tri(propylene glycol) butyl ether) was chosen as a model system. In addition to the cationic-non-ionic system, the mixture of anionic-non-ionic surfactants (sodium dodecyl sulphate and tri(propylene glycol) butyl ether) was investigated. The foam behavior of one-component solutions and binary mixtures was characterized as a function of surfactant concentration, number of carbons (n) in alkyl chain of CnTAB as well as type of surfactant. It was shown that synergism in foamability could be produced by the ionic-non-ionic systems, and the concentration below the synergism occurs, called the critical synergistic concentration (CSC), that can be easily predicted based on the surface tension data on individual components.

Aqueous Foams in the Presence of Surfactant Crystals.

Aqueous foams are used extensively in many fields and anionic surfactants are commonly used foaming agents. However, potential trouble may arise when they are utilized in hard water areas and/or at low temperatures. Anionic surfactants, like sodium dodecyl sulfate (SDS), may precipitate in the form of crystals when the concentration of divalent counterions such as Mg2+ exceeds a certain limit. In an attempt to prepare ultrastable foams containing precipitated crystals, the behavior of SDS in water was systematically investigated as a function of surfactant concentration at different concentrations of Mg(NO3)2 prior to a study of their foam properties. We quantitatively study the conversion of surfactant micelles to crystals and the redissolution of crystals into micelles. It was found that the presence of surfactant crystals reduced the initial foam volume and foam half-life but greatly improved the long-term stability of foams. Foam studies were also conducted for the supernatant and sediment isolated from crystal dispersions so that the importance of surfactant crystals to foam stability could be established. Despite the foamability of a sediment being low, an order of magnitude increase in foam half-life was related to the coverage of bubble surfaces by surfactant crystals. Both rapid cooling and ultrasonication were shown to influence the surfactant crystal shape and size with an impact on foam properties.