Mixtures Of Sodium Dodecyl Sulfate Research Articles

Controlling the optimum surfactants concentrations for dispersing carbon nanofibers in aqueous solution

As a new nano-scale functional material, it is necessary to achieve a uniform distribution in the composites for gaining the CNFs’ excellent reinforcing effect. In this paper, CNFs were purified by the method of high temperature annealing treatment. Six surfactants, methylcellulose (MC), hydroxypropyl methylcellulose (HPMC), sodium dodecyl sulfate (SDS), dodecylamine (DDA), N, N-dimethyl formamide (DMF) and cetyltrimethyl ammonium bromide (CTAB) were used individually and combinatorially in a certain concentration to disperse the CNFs in aqueous solution. To achieve a good dispersion of the CNFs, a method utilizing ultrasonic processing was employed. The CNFs treated by the method of high temperature annealing treatment were characterized by differential thermal analysis (DTA) and thermogravimetry analysis (TGA), and the ultrasonication-driven dispersion of CNFs in aqueous solutions were monitored by UVvis spectroscopy and transmission electron microscopy (TEM). The experiments reveal that the method of high temperature annealing treatment purified the CNFs and the maximum achievable dispersion of CNFs corresponds to the maximum UV absorbance of the solution. All results show that the surfactants mixture of MC and SDS in a certain concentration of 0.4 and 2.0 g/L has the maximum dispersion effect on CNFs in aqueous solution, the optimum concentration ratio of MC, SDS, and CNFs was 2: 10: 1.

Changes in the shape of atomic lines of alkali metals in sonoluminescence spectra of solutions of surfactants and halogenides

The multibubble sonoluminescence spectra of aqueous solutions of sodium dodecyl sulfate, of the mixture of sodium dodecyl sulfate with lithium and potassium chlorides, and of sodium and potassium halogenides were measured near the lines of metals at an ultrasonic frequency of 20 kHz. The Na, Li, and K lines in spectra of surfactant solutions are noticeably narrower than those obtained in solutions of metal chlorides. The width of Na lines in spectra of metal fluorides, chlorides, and iodides remains constant, while that of the K line increases with increasing atomic weight of a halogen. The results are discussed in the context of the effect that the bonding strength of an atom possibly has on the formation of metal lines in sonoluminescence spectra.

Kinetic study of carbon dioxide hydrate formation in presence of silver nanoparticles and SDS

The effects of synthetized silver nanoparticles and sodium dodecyl sulfate (SDS) on carbon dioxide hydrate formation rate and storage capacity have been studied in this work. Aqueous solution of SDS with concentrations of 300 and 500ppm, suspension of silver nanoparticles with concentrations of 0.000045 and 0.00009M, and the mixture of SDS (500ppm) and silver nanoparticles (0.000045M) were tested in a 460cm3 stirred batch reactor. The experiments were conducted at temperatures (273.65 and 275.65)K and initial cell pressures (2 and 3)MPa. Our results show that SDS and silver nanoparticles do not have significant effect on decreasing the induction time and increasing the storage capacity of CO2 hydrates. However, the mixture of SDS and silver nanoparticles significantly increase the storage capacity of carbon dioxide. A diffusion-reaction kinetics model is used to predict the hydrate growth rate. Analyzing the growth rates at the start of hydrate formation show that, the addition of SDS and silver nanoparticles increases the apparent rate constant and the mixture of SDS and silver nanoparticles is most effective in enhancing the apparent rate constant.

Impact of Different Surfactants and their Mixtures on Methane‐Hydrate Formation

AbstractGas hydrates can be used as a potential means for natural gas storage. Design of a gas‐hydrate‐based unit requires accurate knowledge of hydrate‐formation kinetics especially in the presence of promoters. In this study, the effects of sodium dodecyl sulfate (SDS), hexa decyl trimethyl ammonium bromide (HTABr), polyoxy ethylene(20) cetyl ether (Brij‐58) and mixtures of SDS with HTABr and Brij‐58 have been investigated to determine their influence on the methane‐hydrate‐formation kinetics and thermodynamics. The study on the kinetics of hydrate formation is focused on the induction time and hydrate‐formation rate. It is found that induction time of hydrate formation in the presence of a promoter is reduced considerably for each test compared with a pure water test. The minimum value of the induction time is found for a mixture of SDS (500 ppm) with HTABr (700 ppm). All of the surfactants and their mixtures can be designated as hydrate‐formation promoters in the concentration ranges studied in the present work and can increase the hydrate‐formation rate. SDS at a concentration of 500 ppm is determined to be the best hydrate‐formation promoter among the surfactants tested. The percent conversion of methane to hydrate is increased in the presence of these surfactants at the end of hydrate formation. The maximum value of the conversion is observed for the 500 ppm concentration of SDS. The results demonstrate that these surfactants and their corresponding mixtures have no significant effect on the thermodynamics of methane hydrate formation.

Micellisation behaviour of mixtures of sodium dodecylsulphate and sodium lauroylsarcosinate in water

The critical micelle concentrations of binary mixtures of sodium dodecylsulphate (SDS) and sodium lauroylsarcosinate (SLAS) have been determined in water by conductivity measurements at different mole fractions for each of the components. The critical micelle concentrations were slightly lower than that predicted from ideal mixing theory indicating positive synergistic interactions in mixed micelle formation. The results of the mixed systems were analysed using the Regular Solution Theory and the approach based on the Gibbs–Duhem equation which allowed for the determination of the composition of the mixed micelle, the activity coefficients and the pair-wise molecular interaction parameter β. The β values were all negative at all mole fractions investigated, showing a slight deviation from ideality, with an average value of –0.27. The excess free energy of the mixed systems was also calculated and the values were all negative for the mixed systems studied, an indication that the mixed micelles are thermodynamically stable relative to the individual component. This thermodynamic parameter also exhibits symmetrical behaviour with respect to micellar composition suggestive of a regular solution behaviour of the mixed surfactant system.

Effects of dispersion surfactants on the properties of ceramic–carbon nanotube (CNT) nanocomposites

Gum Arabic (GA), Sodium Dodecyl Sulphate (SDS) and their mixture were used for the dispersion of multi-walled carbon nanotubes (CNTs) in an alumina matrix. A good dispersion at low loadings (0.5–1 wt%) of CNTs in alumina was achieved by an ultrasonic bath treatment. Dispersions were evaluated by UV–vis spectroscopy and agglomerate size analysis. The mixture of GA and SDS produced good dispersion as compared to GA and SDS alone. Nanocomposite powders were sintered by Spark Plasma Sintering (SPS). Microstructural, electrical and mechanical characterizations of sintered discs were carried out to evaluate the effectiveness of the different dispersants. The mixture of GA and SDS produced homogeneous and agglomerate-free CNT-alumina nanocomposites with higher electrical conductivity and indentation fracture toughness as compared to nanocomposites prepared using GA and SDS alone.

Foams stabilized by mixed cationic gemini/anionic conventional surfactants

The mixed adsorption of a cationic gemini surfactant, ethanediyl-1,2-bis(dodecyldimethylammonium bromide) (abbreviated as 12-2-12), and an anionic conventional surfactant, sodium dodecyl sulfate (SDS), was examined using surface tension measurements. The viscoelastic properties of the mixed films were investigated by dilational interfacial rheology technique. The results showed that the addition of SDS promoted the close packing of adsorbed molecules at the interface, which increased the dilational elasticity of the mixed films. The stability of the foams was determined by the half-life of foam height collapse. The foams generated by 12-2-12/SDS mixtures were more stable than that formed by pure 12-2-12. In the presence of sodium bromide, the foam stability was further enhanced and the surfactant concentration required to attain the maximum effect in stabilizing foams was greatly reduced. The high foam stability could well relate to the high elasticity of the film.

Adsorption of the Linear Poly(ethyleneimine) Precursor Poly(2-ethyl-2-oxazoline) and Sodium Dodecyl Sulfate Mixtures at the Air–Water Interface: The Impact of Modification of the Poly(ethyleneimine) Functionality

The adsorption of the polymer-surfactant mixture of poly(2-ethyl-2-oxazoline)-sodium dodecyl sulfate at the air-water interface has been studied by neutron reflectivity and surface tension. The observed patterns of adsorption more closely resemble those encountered in weakly interacting polymer-surfactant mixtures, rather than the pronounced enhancements in adsorption observed in strongly interacting polymer-surfactant mixtures, such as in the related poly(ethyleneimine)-sodium dodecyl sulfate mixtures. The adsorption was found to be strongly dependent on solution pH, polymer molecular weight, and polymer concentration. At the lower and higher molecular weights studied, there was little enhancement in the sodium dodecyl sulfate adsorption at low sodium dodecyl sulfate concentrations, whereas at the intermediate polymer molecular weights, some enhancement in the adsorption was observed. For the higher-molecular-weight polymers and at increasingly higher polymer concentrations, a significant reduction of the surfactant at the interface compared to pure sodium dodecyl sulfate occurred for sodium dodecyl sulfate concentrations between the critical aggregation concentration and the critical micellar concentration. The results illustrate the important role of modifying the functionality of poly(ethyleneimine) on surface adsorption.

Storage capacity of carbon dioxide hydrates in the presence of sodium dodecyl sulfate (SDS) and tetrahydrofuran (THF)

The storage capacity, induction time and induction temperature of CO2 hydrates were investigated on pure water, SDS solutions, THF solutions and mixtures of THF and SDS. SDS did not present significant effect on increasing storage capacity, as it is usual to methane hydrates. However, mixtures of SDS and THF presented maximum % theoretical, 121(±12)% and reduction of temperature and time for induction, due to a synergistic effect.

Phase Behavior and Molecular Thermodynamics of Coacervation in Oppositely Charged Polyelectrolyte/Surfactant Systems: A Cationic Polymer JR 400 and Anionic Surfactant SDS Mixture

Coacervation in mixtures of polyelectrolytes and surfactants with opposite charge is common in nature and is also technologically important to consumer health care products. To understand the complexation behavior of these systems better, we combine multiple experimental techniques to systematically study the polymer/surfactant binding interactions and the phase behavior of anionic sodium dodecyl sulfate (SDS) surfactant in cationic JR 400 polymer aqueous solutions. The phase-behavior study resolves a discrepancy in the literature by identifying a metastable phase between the differing redissolution phase boundaries reported in the literature for the surfactant-rich regime. Isothermal titration calorimetry analyzed within the framework of the simple Satake-Yang model identifies binding parameters for the surfactant-lean phase, whereas a calculation for polymer-bound micelles coexisting with free micelles is analyzed in the surfactant-rich redissolution regime. This analysis provides a preliminary understanding of the interactions governing the observed phase behavior. The resulting thermodynamic properties, including binding constants and the molar Gibbs free energies, enthalpies, and entropies, identify the relative importance of both hydrophobic and electrostatic interactions and provide a first approximation for the corresponding microstructures in the different phases. Our study also addresses the stability and metastability of oppositely charged polyelectrolytes and surfactant mixtures.

Semicontinuous heterophase copolymerization of vinyl acetate and butyl acrylate

AbstractVinyl acetate (VAc) and butyl acrylate (BuA) were copolymerized in heterophase by a semicontinuous process (unseeded) and compared with the seeded semicontinuous microemulsion polymerization of the same monomers. A mixture of sodium dodecyl sulfate (SDS) and poly(ethylene oxide) dodecyl ether (Brij‐35®) were used as surfactants. The effects of monomer addition rate (Ra) and surfactants concentrations (4 or 1 wt % with respect to the initial mixture of reaction) on polymer and latex properties were studied. High copolymer content latexes (24–36 wt %) with average particle diameters (Dp) from 38 to 55 nm and relatively narrow particle size distributions, high polymerization rates, weight ratios of polymer to surfactant (P/S) from 13.3 to 32.8 were obtained. The number‐average molecular weights (Mn) were between 96,000 and 188,000 g/mol. Homogeneous copolymer compositions were obtained throughout the reaction for both, seeded and unseeded processes, which is not possible by the usual batch microemulsion process. © 2012 Wiley Periodicals, Inc. J. Appl. Polym. Sci., 2013

Effect of Sodium Dodecyl Sulfate on Volumetric Properties of Methanol Ethanol n-Propanol and iso-Propanol at (298.15 - 323.15)K

The critical micelle concentration (CMC) of Sodium dodecyl sulfate (SDS) in water was determined from the conductance and viscosity measurement. The estimated value of CMC was found to be 0.0085 mol.L-1 at 29°C. The concentration of SDS in pre-micellar and postmicellar region of 0.005M and 0.01M, respectively were used for the volumetric measurements of Methanol, Ethanol, n-Propanol and iso- Propanol with SDS solutions. Densities of ternary mixtures of Methanol, Ethanol, n-Propanol and iso-Propanol with 0.005M and 0.01M aqueous SDS have been studied over the entire range of composition at 298.15- 323.15K with an interval of 5K except Methanol. Methanol system was studied at 298.15-308.15K due to its low boiling point. The values of excess molar volumes, VE for all the systems are negative over the entire range of composition, showing minima at ~ 0.45 mole fraction of Methanol, ~ 0.4 mole fraction of Ethanol, ~ 0.25 mole fraction of n-Propanol and ~ 0.3 mole fraction of iso-Propanol. All the systems are showing minima at aqueous SDS rich region. The VE values for the n-Propanol + aqueous SDS and iso-Propanol + aqueous SDS mixtures are slightly sigmoid, being negative at lower mole fractions (x2) and positive at higher x2 of Propanols. The excess properties (VE) data have been fitted by the least square method to the four parameter Redlich-Kister equation and the values of the parameter aj have been reported.DOI: http://dx.doi.org/10.3329/dujs.v60i1.10351 Dhaka Univ. J. Sci. 60(1): 129-136 2012 (January)

Effect of β-Cyclodextrin Upon the Sol-gel Transition of Methylcellulose Solutions in the Presence of Sodium Dodecyl Sulfate

The sol-gel transition temperature of methylcellulose (MC) solution in the presence of sodium dodecyl sulfate (SDS) as well as the mixtures of SDS and β-cyclodextrin (β-CD) was measured, and the effect of the two competing interactions, the hydrophobic interaction between SDS and MC and the inclusion interaction between SDS and β-CD, upon the sol-gel transition of MC solution was studied. It has been found that the inclusion interaction between SDS and β-CD is much greater than the hydrophobic interaction between SDS and MC. As a result, in the coexistence of SDS and β-CD, the sol-gel transition temperature of MC solution keeps the same value, independent of the concentration of SDS in solution on condition that the concentration of SDS is less than β-CD. Our experimental results not only suggest that the effect of SDS upon the sol-gel transition of MC solution can be screened by β-CD completely but also indicate the inclusion ratio of SDS to β-CD can be determined quantitatively by using rheological measurement. The inclusion ratio of SDS to β-CD is 1:1, which is in good agreement with the inclusion ratio of SDS to β-CD in the presence of poly(vincyl pyrrolidone) determined by the viscosity measurement but is critically different from the inclusion ratio of SDS to β-CD in the presence of the oppositely charged polyelectrolyte by using the rheological measurement, mainly due to the reason that the mechanism of the interaction between SDS and MC is critically different from the mechanism of the interaction between SDS and the oppositely charged polyelectrolyte.

Experimental Study on Dynamic Interfacial Tension with Mixture of SDS–PEG as Surfactants in a Coflowing Microfluidic Device

In this work, a coflowing microfluidic device was used to determine the influence of different mixed sodium dodecyl sulfate (SDS)-poly(ethylene glycol) (PEG) compound systems on dynamic interfacial tension and, by extension, corresponding emulsion droplet sizes. The aqueous solutions were used as the continuous phase in the microfluidic device, while octane was used as the organic dispersed phase. Combined SDS-PEG systems lower the interfacial tension more than either component can alone up to the critical aggregation concentration (CAC) of SDS. Octane droplet sizes produced in the microfluidic device using combined SDS-PEG systems were smaller than those produced using SDS alone, and a reduction in dynamic interfacial tension as determined by drop size followed a pattern similar to that observed in the static case (PEG4000 > PEG600 > PEG400 > PEG200 > PEG8000) with the exception of PEG8000. Finally, a previously formulated model relating interfacial tension to droplet size was used to estimate the dynamic interfacial tensions in the microfluidic device.

A novel method for PbS quantum dot synthesis

A novel way to synthesize cubic PbS quantum dots (QDs) with average sizes of about 3nm to 5nm is presented in the current research. A mixture of sodium dodecyl sulfate (SDS) and cetyltrimethyl ammonium bromide (CTAB) was used as stabilizing agent and ethylene diamine tetraacetic acid (EDTA) was used as dispersant in the chemical bath synthesis method. The role EDTA that plays in the fabrication of PbS QDs was also analyzed. PbS QDs could not be synthesized without EDTA even with the use of stabilizing agents SDS and CTAB. EDTA facilitates the formation of stable complex compounds with Pb2+ metal ions and prohibits the aggregation of PbS QDs.

계면활성제 거품(Foam)을 이용한 토양칼럼 내 유류 및 중금속 동시 제거 연구

Simultaneous removal of heavy metals (Cd, Pb) and diesel-fuel from a soil column was evaluated by respectively flushing with sodium dodecyl sulfate (SDS) solution, mixture of SDS and sodium iodide (SDS + NaI), and surfactant foam (SDS + NaI foam). First, this study evaluated these flushing methods to the heavy metals only-contaminated soil for removal of heavy metals from the heavy-metal only contaminated soil column. After 7 pore volume flushing of the soil column, Cd removal efficiencies from the soil were 40% by SDS solution, 50% by SDS + NaI mixture, and 60% by surfactant foam. The flushing results implied that anionic surfactant and ligand can be efficiently applied to extraction of Cd from the heavy metal contaminated soil. Furthermore, surfactant foam flushing showed an increased flushing efficiency with enhancing the contact between surfactant solution and soil. However, Pb removal efficiency by these flushing methods did not show any difference unlike those of Cd. Second, this study eventually evaluated flushing methods for simultaneous removal of heavy metals and diesel-fuel from the soil column with 7 pore volume flushing. Diesel-fuel removal efficiencies were 50% by SDS + NaI flushing and 90% by SDS + NaI foam flushing. Cd removal efficiency by the foam flushing reached to 80% which was higher than the result of the previous heavy metals onlycontaminated soil experiment. This result implied that diesel-fuel could act as a metal-solvent while it contacted to heavy metals present in the soil. This study clearly showed that surfactant foam flushing simultaneously removed heavy metals and diesel fuel from the soil column.

Selective Tellurium Nanowire‐based Sensors for Mercury(II) in Aqueous Solution

AbstractWe have developed a simple, colorimetric, and label‐free tellurium nanowire (Te NW)‐based probe for the detection of mercury ions (Hg(II)) in aqueous solution, operating on the principle of strong hybridization and galvanic replacement reaction of Te–Hg. The Te NWs (length: 920 nm; diameter: 20 nm) reacted with Hg(II) to induce dissolution and aggregation of the Te NWs. As a result, the absorption band of the Te NWs in a solution undergoes a decrease in the presence of Hg(II). Energy‐dispersive X‐ray spectroscopy and surface‐assisted laser desorption/ionization measurements demonstrated the presence of Hg on the Te NWs. The Te NW probe specifically and sensitively detected Hg(II) ions under optimal concentrations of pH, temperature, and sodium dodecyl sulfate (SDS) concentration. When using a mixture of Te NWs (3.0 nM) and SDS (5 μM) in 5 mM sodium phosphate (pH 4) at 50 °C, this sensor provides a limit of detection of 0.5 nM for Hg(II) (signal‐to‐noise ratio of 3) with high selectivity (at least 100 fold over other metal ions). Our approach abrogates the need for complicated chemosensors or sophisticated equipment. This cost‐effective sensing system allows the rapid and simple determination of the concentrations of Hg(II) ions in real samples (in this case, river, lake, and tap water samples).

Assessment of different sorbents efficiency for solid phase extraction of aquatic humic acids

Abstract In the present study, a simple procedure for the isolation by solid-phase extraction (SPE) and quantification by UV-Vis spectrometry (400 nm) of the humic acids (HAs) in the natural waters was developed. Seven different sorbents: Porapak P (polystyrene-divinylbenzene copolymer), Florisil (chemical composition: 84.0% SiO2, 15.5% MgO and 0.5% Na2SO4), Silica gel C18 (octadecyl silane), Strata X (surface modified polystyrene-divinylbenzene), Strata NH2 (silica-based trifunctional amino ligand), Strata SAX (silica-based trifunctional quaternary amine) and Strata C18-E (silica-based trifunctional C18 with hydrophobic end-capping of silanols) were tested. The HAs, adsorbed on SPE cartridges, were eluted using: NaOH (0.1 M), sodium dodecyl sulphate (SDS) (20 g L−1), and a 1:1 v/v mixture of SDS (20 g L−1) and NaOH (0.1 M). The extraction efficiency was evaluated by comparing the HAs recovery levels. The repeatability of results was estimated by the relative standard deviation (RSD). The data confirmed that Porapak P, Silica gel C18, Florisil, Strata NH2 and Strata X could be good alternatives for the traditional isolation of the aquatic HAs with XAD resin. The proposed method was applied for the determination of HAs in some waters sampled from the Western Romanian Plain. The content of HAs was correlated with the arsenic concentration and total organic carbon (TOC) level.

Extraction Separation of BSA in Aqueous Two-Phase Systems of Anionic and Cationic Surfactant Mixtures

Aqueous two-phase systems (ATPS) are formed in mixtures of sodium dodecylsulfate (SDS), cetyltrimethyl ammonium bromide (CTAB), and sodium bromide (NaBr). Two different kinds of ATPS appear when CTAB and SDS surfactants are in excess, respectively. Such ATPS may provide a new, useful partitioning system for separation of bovine serum albumin (BSA). The partitioning of BSA was studied in these systems. The results show that the partitioning is affected by the electrical property, the hydrophobicity and the structure of liquid crystal (LC), which exists in the top phase of the ATPS. BSA is extracted into the top phase with higher distribution coefficient when LC and BSA are oppositely charged. The hydrophobicity of LC, which can be improved by increasing the length of alkyl group, enhances the distribution coefficient. The hydrophobicity of lamellar LC and hexagonal LC is stronger than that of cubic LC, which causes extractive capability of the former is higher than the latter.

Electrolyte effect on adsorption and the phase transition from microstructures to nanostructures in ionic/ionic surfactants mixture

The effect of salt concentration on intermicellar interactions and aggregate structures of anionic and cationic-rich mixtures of CTAB (cetyltrimethylammonium bromide) and SDS (sodium dodecyl sulfate) were investigated with conductometry, surface tension, zeta potential, cyclic voltammetry measurements and by determining the surfactant NMR self-diffusion coefficients. The critical aggregate concentration (CAC), surface excess (Γmax), and mean molecular surface area (Amin) were determined from plots of the surface tension (γ) as a function of the log of total surfactant concentration. The electrochemical behavior of cationic–anionic (catanionic) mixed surfactant and self-assembled surfactant monomers at Pt wire electrode were studied by cyclic voltammetry (CV). A variation in the peak current versus the total concentration of surfactant allow us to evaluate the CAC and related parameters from regular solution theory along with the diffusion coefficient of the electroactive species. It was observed that, for both the planar air/aqueous interface and micellar systems, the nonideality decreased as the amount of electrolyte in the aqueous medium was increased. Finally, we investigated the variations of electrostatic, transfer and steric free energy in phase transition between mixed micelle and vesicle in the presence of electrolyte using the presented model by our groups.