Concentrations Of Anionic Surfactants Research Articles

Size Regulation and Photoluminescence Properties of <i>β</i>-Ga<sub>2</sub>O<sub>3</sub> Nanomaterials

Gallium oxide (Ga<sub>2</sub>O<sub>3</sub>) nanomaterials have great potential in the fields of ultraviolet transparent electrodes, high-temperature gas sensors, solar blind ultraviolet detectors and power devices, while achieving Ga<sub>2</sub>O<sub>3</sub> nanomaterials with high crystalline quality and controllable size and morphology still remains challenge. Herein, size-controllable Gallium oxide hydroxide (GaOOH) nanorods, nanorod bundles, and spindles were prepared by hydrothermal method. After high temperature calcination, GaOOH nanomaterials were successfully transformed into higher-quality single-crystal β-Ga<sub>2</sub>O<sub>3</sub> nanomaterials which well retained the morphological characteristics of the pristine GaOOH.With the help of X-ray diffraction (XRD), Raman scattering spectroscopy (Raman) and field emission scanning electron microscope (FE-SEM), we systematically studied the influence of the pH value and the concentration of anionic surfactants in the precursor solution on the crystal structure and surface morphology of GaOOH and β-Ga<sub>2</sub>O<sub>3</sub> nanomaterials, and explored the different growth mechanism of GaOOH nanomaterials under different conditions. Simultaneously, room temperature photoluminescence (PL) tests revealed that β-Ga<sub>2</sub>O<sub>3</sub> nanomaterials with different morphologies exhibit typical broad blue-green emission and sharp red emission, which are closely related to the existence of intrinsic defects in nanomaterials.The above research results provide valuable information for the controllable preparation of high-quality β-Ga<sub>2</sub>O<sub>3</sub> nanomaterials.

Structure, rheological and responsive properties of a new mixed viscoelastic surfactant system

A new viscoelastic surfactant system based on a mixture of cationic (n-dodecylpyridinium chloride) and anionic (potassium oleate) surfactants was prepared. The effect of the concentration of cationic surfactant at constant concentration of anionic surfactant on the structure and rheological properties was investigated. A transition from spherical to cylindrical micelles was observed upon increasing content of cationic surfactant. SANS data revealed that the cylindrical micelles have an elliptical cross-section with a major axis close to double length of oleate tail and minor axis close to the double length of n-dodecyl tail suggesting that the both surfactants are segregated in some way within the micelles. The local segregation of surfactants was confirmed by 1H NMR NOESY data. The rheological data show that the viscosity goes through maximum with increasing content of cationic surfactant, which is due to the growth of micelles in length (before the maximum) and their branching (after the maximum). A maximum viscosity was found at a molar ratio between cationic and anionic surfactants equal to 0.3. The mixed surfactant system was shown to be responsive to hydrocarbons, since added n-decane induced a decrease of viscosity by 5 orders of magnitude as a result of transformation of long cylindrical micelles into ellipsoidal microemulsion droplets as was evidenced by SANS.

Occurrence, fate and environmental risk of anionic surfactants, bisphenol A, perfluorinated compounds and personal care products in sludge stabilization treatments

In this work, twenty-three endocrine disrupting compounds have been monitored in sludge from different stages of four sludge stabilization treatments (anaerobic digestion, aerobic digestion, composting and anaerobic stabilization ponds). Their occurrence and fate in sludge stabilization plants and their potential environmental risk in treated sludge and in treated sludge-amended soils have been evaluated. Monitored compounds were six perfluoroalkyl compounds (PFC), four anionic surfactants (sodium alkylsulfates), a plasticiser (bisphenol A (BPA)), four preservatives (parabens), six UV-filters (benzophenones) and two biocides (triclosan and triclocarban). Only two of the UV-filters were not detected in any of the 141 analysed samples. Anionic surfactants (mean concentrations up to 1673 ng/g dry matter (dm) for the sum of surfactants) were the compounds at the highest concentration levels followed by biocides (up to 512 ng/g dm) and UV-filters (up to 662 ng/g dm). The concentrations of anionic surfactants, preservatives and UV-filters decreased 78, 25 and 80%, respectively, after anaerobic digestion. The concentration of perfluorinated carboxylic acids only decreased after composting (80% reduction) whereas biocides and BPA were not affected by any of the studied treatments. Environmental risks (risk quotients > 1) were obtained for all compounds, except for triclocarban and sodium octadecylsulfate, in treated sludge. In treated sludge-amended soils, risk quotients were lower than 1 for all compounds except for triclosan.

Dependence of Surface Tension on Surface Concentration in Ionic Surfactant Solutions and Influences of Supporting Electrolyte Therein

Abstract It has been well-known that the addition of electrolytes causes the ionic surfactant solution to have a lower surface tension by stimulating the surface adsorption. When the surface concentration of an ionic surfactant remains constant, the solution with supporting electrolyte in the bulk displays a lower surface tension than a solution without electrolyte. From the surface perspective we investigate the dependence of the surface tension of a solution upon the surface concentration of ionic surfactant and the influences of the supporting electrolyte therein, by means of thermodynamics and molecular dynamics simulation. The derived thermodynamic formula and simulation results predict, that at a given surface concentration the supporting electrolyte can change the orientation of the ionic surfactant, which results in a lower surface tension. The conclusions can be useful for the investigation to the surface structure of ionic surfactant solutions and the effects of supporting electrolyte.

Biodegradation of anionic surfactants in the bioremediation of oil-polluted soil

Surfactants are applied as emulsifiers or solubilizers by treatment of polluted soil. Theproblem of secondary pollution has arisen as result of the surfactant-enhanced remediation ofa polluted soil contaminated with hydrophobic organic compounds. Several studies haveshown that the surfactants are biodegradable in aerobic conditions and the biodegradabilitydepended on the chemical properties and concentration of surfactant. A study of the leachingof surfactants from the soil is important, as it is difficult to identify the reason for thereduction of concentration of pollutants in the soil: is it degradation or leaching? Theexperiments were carried out with a fine sandy soil in column tests and CaCO3 was added toincrease soil pH. The soil was treated twice with the bioremediation agent SR-100. The soilpH, the concentrations of anionic surfactant and petroleum hydrocarbons at the differentdepths of soil were determined. The microbial activity of soil fractions was evaluated byrespirometer. The concentration of surfactants was determined colorimetrically as MethyleneBlue active substances (MBAS). The concentration of anionic surfactants decreased in theupper layer of the columns, but it increased in the lower layers. It indicated the leaching ofthe anionic surfactants from soil during experiments of 60 days. The amounts of residualsurfactants were lower in the samples of polluted soil in comparison with unpolluted soil. Thesamples of lower soil fractions had higher microbial activity in comparison with upperfractions. Soil pH was measured as pHH20, pHKcl and pHcac12 instead of the pH of soilsolution, because soil was too dry. The pH of fine sandy soil was 5.8 and during theexperiment the value of pH increased in the lower layer of soil till pHH20 = 7.5.

Norm descriptors for predicting the hydrophile-lipophile balance (HLB) and critical micelle concentration (CMC) of anionic surfactants

The hydrophile-lipophile balance (HLB) and critical micelle concentration (CMC) are vitally important indexes to measure the performance of surfactants quantitatively. Herein, based on the concept of norm index, new norm descriptors were proposed for describing the HLB and CMC of anionic surfactants, and two QSPR models were built to calculate the two values. Results showed that the norm descriptors-based models could give satisfactory prediction effect for the HLB and CMC of anionic surfactants with the R2 of 0.9983 for HLB and R2 of 0.9130 for CMC. The satisfactory results of several validations demonstrated that these models were stable, reliable and had a very good predictive ability. Moreover, for anionic surfactants without experimental values, the predicted HLB of 19 anionic surfactants and predicted CMC of 101 anionic surfactants were respectively calculated using the proposed models. The above results indicated that the norm index was suitable for evaluating the HLB and CMC.

Effect of Ion Pairs on Nonlinear Optical Properties of Crystal Violet: Surfactants, Nano-droplets, and In Vitro Culture Conditions

Crystal violet (CV) has nonlinear optical (NLO) properties that make it suitable for photodynamic therapy. In this respect, Z-scan technique is applied to find the influence of surfactants and nano-droplets on NLO properties of CV. Nonlinear absorption coefficient and nonlinear refractive index can be further determined. The NLO parameters are also enhanced by the increase in anionic surfactant concentrations, while they remain constant with the rise in cationic ones. Moreover, the NLO parameters are extremely improved in dye-doped water droplets prepared with anionic surfactant and a continuous phase of low-polarity oils. It has been demonstrated that the interaction of ion pairs can change linear optical and NLO properties of CV that in turn can change the charge density distribution. To study the behavior of dye during in vitro culture conditions, the effect of cell culture media and fetal bovine serum on NLO properties of CV was examined.

Ionic-surfactant-mediated electro-dewetting for digital microfluidics.

The ability to manipulate droplets on a substrate using electric signals1-known as digital microfluidics-is used in optical2,3, biomedical4,5, thermal6 and electronic7 applications and has led to commercially available liquid lenses8 and diagnostics kits9,10. Such electrical actuation is mainly achieved by electrowetting, with droplets attracted towards and spreading on a conductive substrate in response to an applied voltage. To ensure strong and practical actuation, the substrate is covered with a dielectric layer and a hydrophobic topcoatfor electrowetting-on-dielectric (EWOD)11-13; this increases the actuation voltage (to about 100 volts) and can compromise reliability owing to dielectric breakdown14, electric charging15 and biofouling16. Here we demonstrate droplet manipulation that uses electrical signals to induce the liquid to dewet, rather than wet, a hydrophilic conductive substrate without the need for added layers. In this electrodewetting mechanism, which is phenomenologically opposite to electrowetting, the liquid-substrate interaction is not controlleddirectlyby electric field but instead by field-induced attachment and detachment of ionic surfactants to the substrate. We show that this actuation mechanism can perform all the basic fluidic operations of digital microfluidics using water on doped silicon wafers in air, with only ±2.5 voltsof driving voltage, a few microamperes of current and about 0.015 times the critical micelle concentration of an ionic surfactant. The system can also handle common buffers and organic solvents, promising a simple and reliable microfluidic platform for a broad range of applications.

Anionic Surfactants and Traffic Related Emission from an Urban Area of Perak, Malaysia.

Anionic surfactants are one of the pollutants derived from particulate matter (PM) and adversely affect the health of living organisms. In this study, the compositions of surfactants extracted from PM and vehicle soot collected in an urban area were investigated. A high-volume air sampler was used to collect PM sample at urban area based on coarse (> 1.5µm) and fine (< 1.5µm) mode particles. Meanwhile, the vehicle soot was collected randomly from the exhaust pipe of various types of diesel and petrol vehicles using a soft brush during dry days. The concentration of anionic surfactants, such as Methylene Blue Active Substances (MBAS), was determined by the colorimetric method using UV-Vis Spectrophotometer. Morphological properties of the PM and exhaust soot sample was studied using field-emission scanning electron microscope. Results revealed that the MBAS concentration was dominated by fine mode particles (6.03 ± 3.97µmolg-1), whereas heavy-duty vehicles, such as buses, demonstrated the highest surfactant concentration with an average value of 0.340 ± 0.180µmolg-1. The structure of collected PM for all samples mostly appeared to be an irregular shape with the size range of ultrafine particles (0.05-0.2µm). The emission of surfactants from diesel and petrol vehicles, especially at urban areas, should be a major concern, because they could negatively affect human health and the environment.

Distribution of Surfactants in the Sea Surface Microlayer and Sub-surface Water in the Melaka River Estuary.

This study determines the levels of surfactants at 12 stations located in the Melaka River Estuary. This river estuary is located within a tourism area of Melaka Historical City. The concentrations of anionic and cationic surfactants in the sea surface microlayer (SML) and sub-surface water (SSW) were determined by using two colorimetric methods, methylene blue active substances (MBASs) and disulphine blue active substances (DBASs), respectively. The results showed that cationic surfactants as DBAS (ranging between 0.19 and 0.25μmolL-1) dominated the concentrations of surfactants in SML. The enrichment factor (Ef) between MBAS and DBAS in the SML and SSW ranged between 1.0 and 2.0, and 1.0 to 1.4, respectively. There was no significant correlation (p > 0.05) between MBAS and DBAS for both SML and SSW. Nevertheless, there were strong correlations (p < 0.05) between both MBAS and DBAS in the SML and SSW. The results showed the potential contribution of degradation processes of organic substances microorganisms in SSW towards the concentrations of surfactants in SML. Compared to previous studies, tourism-related activities may influence the concentrations of surfactants, especially DBAS, in this river estuary.

Determination of the critical micelle concentration by absorbance and fluorescence techniques using fluorescein probe

We reported a unique and sensitive probe (fluorescein) for determination the critical micelle concentration(CMC) of ionic surfactants based on both fluorescence and absorbance properties of probe in micellar solution. We found that the spectral properties (fluorescence and absorbance) of fluorescein are affected by different types of surfactants. For this purpose spectrophotometric technique using fluorescein as probe to determine the critical micelle concentration of cationic, anionic and zwitterionic surfactants. The critical micelle concentrations of surfactants were determined from the sigmoidal shaped plots or inflection points. The obtained CMC values were in good agreement with the values obtained with conductivity measurements or with literature values.

Effect of Charge and Dielectric Constant on Linear and Nonlinear Optical Properties of Two Dyes

The enhancement of nonlinear optical properties of dye with surfactant can be applied in photodynamic therapy and medicine. The nonlinear optical properties of alizarin red S and rhodamine B mixed with cationic and anionic surfactant are studied by Z-scan technique. The nonlinear absorption coefficient values of cationic dye (rhodamine B) in aqueous solution are reduced with the increase of anionic surfactant concentration, while the nonlinear absorption coefficient values are enhanced by the interaction between anionic dye (alizarin red S) with anionic surfactant. The nonlinear refractive index (n2) of cationic and anionic dye is reduced with an increase of surfactant concentration. The nonlinear absorption coefficient values of a rhodamine B-doped droplet is reduced by the increase of cationic surfactant in the water droplet. In general, the nonlinear absorption coefficient values are reduced with an increase of dye solubility, and the value of n2 is reduced with an increase of dye solubility in solution. The fluorescence intensity is higher when dye and surfactant have the same charge. This effect can be due to the increase of solubility of cationic (anionic) dye with an increase of anionic (cationic) surfactant in the solution. The reduction of nonlinear absorption coefficient values with an increase of droplet size can be due to the change of rhodamine B solubility in microemulsion.

Potential for anaerobic treatment of wastewater from pet bottle washing in a fluidized bed reactor

This study evaluated the potential of anaerobic treatment of wastewater from washing polyterephthalate ethylene (PET) bottles sent to recycling (WWPR) in a fluidized bed reactor. The reactor had a total volume of 2.16 L and was fed with the WWPR diluted in a nutritional medium operated with a hydraulic retention time (HRT) of 24 h and maintained at a temperature of 33 ± 2 °C. Coarse sand was used as a support material for the immobilization of biomass in the reactor. The potential of the anaerobic system was evaluated as a result of the progressive increase in chemical oxygen demand (COD) and anionic surfactants, both from the WWPR. The biomass was subjected to an immobilization and adaptation process over 10 days, and after this period, concentrations of anionic surfactants were added. The maximum COD load removed was 2.6 ± 0.43 kg/m³d, which represented a removal of 64 ± 8%. The maximum surfactant removal was 0.063 ± 0.001 kg/m³d for an initial concentration of 15 mg/L. The fluidized bed reactor was stable and robust in relation to the applied load of organic matter; however, surfactant removal was inhibited at initial concentrations above 30 mg/L.

Wettability Alteration of Carbonate Reservoir Cores—Laboratory Evaluation Using Complementary Techniques

Summary The objective of this paper was to assess the applicability of relatively low-salinity brine and different surfactants for enhanced oil recovery (EOR) in carbonate reservoirs in the Middle East. Phase behavior, interfacial tension (IFT), contact angle, spontaneous imbibition, and ζ-potential experiments were performed. The experimental work flow included a phase-behavior study followed by IFT, contact-angle measurements, spontaneous-imbibition measurements, and ζ-potential measurements at varying salinities and surfactant concentrations. Contact-angle-measurement results indicated that surfactant solutions, in addition to lowering IFT, tend to change the core wettability from oil-wet or neutral-wet to more water-wet. Furthermore, the best results were achieved by adding an anionic surfactant. Moreover, spontaneous imbibition and ζ-potential measurements provided additional supporting data that diluted seawater (DSW), in a dilute anionic or nonionic surfactant solution, alters the wettability of carbonates to a favorable wetting state for improving oil recovery. This research presents a set of diverse experimental data that confirms adding low concentrations of anionic and nonionic surfactants to DSW improves oil recovery from carbonate reservoirs.

Assessment on overall efficiency of urban greywater treatment by vermifiltration in hot climate: enhanced pollutants removal

ABSTRACT Vermifiltration technology using Eudrilus Eugeniae could be an alternative low-cost option for the treatment of urban greywater, which is highly polluted with high concentrations of surfactants, sodium and cooking oil. In this study, the effects of these pollutants on performance of a vermifiltration system was tested over a period of 6 to 8 weeks by enriching raw greywater with various concentrations of anionic surfactants (0, 15, 45 and 135 mg/L), sodium (0, 1, 2 and 4 g/L) and refined palm cooking oil (0, 250 and 500 mg/L). The vermifilter system was made of gravel, sand and sawdust layers from the bottom to the top, on which 200 earthworms were added. The greywater used in this study was previously used for dishwashing and laundry by an urban poor household. The greywater quality was compared with the effluent to evaluate the system performance. BOD5, COD, TSS and E. coli removal efficiencies ranged from 93% to 98%, 68% to 93%, 88% to 96% and 1.4-3 ULog, respectively, which are within the range of efficiencies reported in the literature. High proportion of surfactants (95–99%) and oil (84–89%) were removed but sodium was not removed. Instead, an increase in sodium concentrations was observed in the filter over the experimental period. Statistical analysis shows that BOD5, COD, TSS and E. coli removal efficiencies were independent of surfactants, cooking oil and sodium concentrations (p < .05). Thus, short term or accidental exposure of the vermifilter to high concentrations of these three pollutants did not have significant effect on the system performance.

Study of Pollution by Anionic Surfactants and Orthophosphates in M’koa Lake (Jacqueville, Côte d’Ivoire)

This study aims to assess the pollution of the surface water from M’koa Lake by both anionic surfactants and orthophosphates, and to identify the sources of pollution by these compounds. Three sampling campaigns were conducted at different seasons at six (6) sampling stations, identified in M'koa Lake by taking into account potential sources of pollution. The measurement of anionic surfactant concentrations was performed by the methylene blue colorimetric method, and the determination of orthophosphates was performed by the vanadomolybdophosphoric acid colorimetric method. In addition, the samples were analyzed in order to find six physico-chemical parameters of surface water quality which are temperature, pH, electrical conductivity, turbidity, oxygen saturation, transparency. The determination of these parameters were made according to both the French AFNOR standard and the methods described by Rodier. The obtained average concentrations of anionic surfactants in the water of M’koa Lake range from 0.23 ± 0.04 mg.L-1 to 1.43 ± 0.68 mg.L-1. Concerning orthophosphates’ content they range from 0.12 ± 0.05 mg.L-1 to 0.17 ± 0.04 mg.L-1. These results indicate that M’koa Lake is subjected to pollution both by anionic surfactants and pollutant enriched by orthophosphate. And, the presence of orthophosphates in lake waters was not due solely to detergents. Washing stations, Berge 1 and 2, and M’koa hotel have the highest levels of anionic surfactants. Also, turbidity and transparency values indicate water quality deterioration of M’koa Lake favoured by the presence of phytoplankton corresponding to the eutrophication of the water of the studied Lake.

Comparison of Electrophoretic Methods for Determination of Critical Micelle Concentration of Anionic Alkylsulfate Surfactants in Water/Organic Environment

The methods for determination of critical micelle concentration of anionic surfactants using capillary electrophoresis instrumentation were compared in this work. We have focused on the determination of critical micelle concentration of homological series of n-alkyl sulfates using four different methods: the electrical current-based method, and method using migration times, retention factors and effective mobilities of n-alkylbenzenes as probe molecules. We have studied the effects of operation conditions (capillary dimensions, applied voltage) and composition of probe samples on the values of critical micelle concentration. The values of critical micelle concentration determined in water and in 25 mmol L−1 borate buffer pH 8.5 without and with addition of 20% (v/v) of acetonitrile ranged from 60 mmol L−1 for sodium nonyl sulfate to 6.1 mmol L−1 for sodium tridecyl sulfate, with higher values for electrolyte containing acetonitrile. The concentration and solvent of probe molecules have significant effect on the determined value of critical micelle concentration. We have studied in detail critical micelle concentration of sodium dodecyl sulfate in mixtures with low concentration of acetonitrile up to the 6% (v/v). In this region, higher uncertainty of determination of critical micelle concentration was experienced.

Sorption of triclosan by carbon nanotubes in dispersion: The importance of dispersing properties using different surfactants

The production of carbon nanotubes (CNTs) increased rapidly due to the superior properties and was suggested to be the potential sorbents for environmental remediation. CNTs tend to form aggregates, thus CNTs dispersion was commonly produced by sonication with surfactant in industry for better application. In the present study, a novel passive sampling method was used to systematically study sorption of triclosan to CNTs dispersion to give a better understanding on their interactions especially with the presence of surface-active substances. With the increase of anionic surfactant concentration (SDBS or SDS), sorption of triclosan was gradually suppressed. CNTs dispersed by nonionic surfactant TX-100 increased or decreased sorption at different TX-100 and triclosan concentration. Little amount of cationic surfactant CTAB(1 mg/L) could sharply decrease triclosan sorption to CNTs but with larger CTAB concentration, sorption was continually increased. Sorption isotherms of triclosan to CNTs dispersion with 40 mg/L and 100 mg/L surfactant fitted well with Toth model show the existence of double competition in the sorption process. Different from the adsorption mechanism of previously aggregated CNTs and compounds. Sorption data combined with comprehensive characterization of CNTs dispersion and theoretical analysis, three effects referring to charge, dispersion and competition were proposed. Sorption coefficient was linearly correlated with the characterization parameters. Surface charge, dispersion status and surfactant concentration play the important role on triclosan sorption in CNTs dispersion in the presence of anionic, cationic and nonionic surfactant, respectively. The results provide basic supports on application of CNTs in remediation area and exploring the fate of both CNTs dispersion and pollutants.

Specific formation of hydrophobic aggregates of ionic thermoresponsive polymers with oppositely charged ionic surfactants under extremely dilute conditions

Cationic and anionic thermoresponsive polymers were synthesized and the formation of their hydrophobic aggregates with ionic surfactants was studied at extremely low polymer concentrations. Alongside the hydrophobic interactions, electrostatic interactions between the ionic groups of the polymers and surfactants played a major role in the formation of the hydrophobic aggregates. In the absence of an ionic surfactant, extremely dilute (i.e., 0.01 wt %) polymer solutions did not become turbid, even when they were heated above the phase-transition temperature. However, above the phase-transition temperature, the polymer solutions became turbid upon the addition of a specific concentration of an ionic surfactant with the opposite charge. In contrast, no increase in the turbidity was observed when an ionic surfactant with the same charge was added to the solution, regardless of the concentration of the ionic surfactant. Even below the phase-transition temperature, the application of a fluorescent probe that responded to the hydrophobicity of its environment revealed that the ionic thermoresponsive polymers formed a hydrophobic environment with oppositely charged surfactants owing to the electrostatic and hydrophobic interactions, even though hydrophobic precipitates were not observed. Thus, the electrostatic interactions between polymers and surfactants played crucial roles in the formation of hydrophobic aggregates under extremely low concentration of the polymers as well as the hydrophobic interactions did.

Surfactant Partitioning in Nanoemulsions.

Using a fractionated silicone oil-in-water nanoemulsion (NEM), which has a high ratio of surface area-to-volume, we investigate surfactant partitioning between the bulk continuous phase and the adsorbed interfacial phase. By adjusting the droplet volume fraction of this fractionated NEM and by using gravimetric and electrical conductivity methods, we measure the bulk and the surface concentrations of an ionic surfactant (sodium dodecyl sulfate, SDS), thereby obtaining a raw adsorption isotherm of SDS on the interfaces of the nanodroplets. To overcome significant uncertainties in the total surface area of this nanoemulsion, we have also measured the macroscopic interfacial tension (IFT) of silicone oil in contact with aqueous SDS solutions using the du Noüy ring method. We then scale the surface concentration of this raw isotherm using an appropriate Gibbs derivative based on the IFT measurement, yielding an adjusted isotherm. We show that this adjusted isotherm can be described using a simple Langmuir equation. In addition, we show that a significant and non-negligible percentage of surfactant typically partitions to nanodroplet interfaces after high-flow-rate emulsification (HFRE) has transformed a microscale premix emulsion into a NEM. We develop a model for predicting the final bulk surfactant concentration after HFRE given the initial bulk surfactant concentration before HFRE. We show that this model can be used to predict trends for surfactant partitioning in polydisperse nanoemulsions after HFRE.