Concentrations Of Anionic Surfactants Research Articles

Flotation of zinc and cadmium cations in presence of manganese dioxide

The subject of this paper is the flotation (foam separation) of zinc and cadmium cations in presence of manganese dioxide precipitate. The removal of zinc cations by adsorbing particulate (particles) flotation (with Tween 80) is higher than that of cadmium ones. It increases both with the increase of the concentration of manganese dioxide precipitate, and that of the nonionic surfactant (Tween 80). The removal of zinc cations by ion flotation (with sodium soaps) is lower than that of cadmium ones. It does not change with the increase of the manganese dioxide precipitate concentration. It increases, however, with the increase of the anionic surfactant (sodium laurate and stearate) concentration. The mechanism of foam separation was discussed on the base of the interaction: (a) between the surface of the manganese dioxide precipitate and the metal cations; (b) between the surface complexes of the precipitate–metal cations and Tween 80; (c) between the metal cations and the sodium soap.

Mechanism of interaction of vincristine sulphate and rifampicin with bovine serum albumin: A spectroscopic study

The mechanism of interaction of vincristine sulphate (VS) and rifampicin (RF) with bovine serum albumin (BSA) has been studied by quenching of BSA fluorescence by RF/VS. The Stern-Volmer plot indicates the presence of a static component in the quenching mechanism. Results also show that both the tryptophan residues of BSA are accessible to VS and RF. The high magnitude of rate constant of quenching indicates that the process of energy transfer occurs by intermolecular interaction and VS/RF-binding site is in close proximity to the tryptophan residues of BSA. Binding studies in the presence of a hydrophobic probe, 8-anilino-1-naphthalene-sulphonic acid sodium salt (ANS) indicate that the VS and RF compete with ANS for hydrophobic sites on the surface of BSA. Small decreases in critical micellar concentrations (CMC) of anionic surfactants in presence of VS/ RF show that the ionic character of VS/RF also contributes to binding. The temperature dependence of the association constant is used to estimate the values of the thermodynamic parameters involved in the interaction of VS/RF with BSA and the results indicate that hydrophobic forces play a significant role in the binding. Circular dichroism studies reveal that the change in helicity of BSA are due to binding of VS/RF to BSA.

Effects of surfactants on the adsorptive removal of basic dyes from water using an organomineral sorbent—iron humate

The sorption of basic dyes (methylene blue, malachite green, rhodamine B, crystal violet) onto a nonconventional organomineral sorbent—iron humate—was examined in the presence of various kinds of surfactants. It was found that nonionic (Triton X-100) and cationic (cetyltrimethylammonium bromide) surfactants exhibited a relatively small effect on the dye sorption. Anionic surfactants (sodium dodecyl sulfate), on the other hand, affected (in most cases) dramatically the sorption of basic (cationic) dyes. Typically, the dye sorption was enhanced in the presence of low concentrations of anionic surfactants. At high surfactant concentrations, a steep decrease in the dye sorption was observed in some systems, probably due to the formation of micelles that solubilize the dye molecules and prevent their sorption. A model describing these experimental dependencies was proposed. The sorption of basic dyes onto iron humate may be described by the pseudo-second-order kinetic equation. Diffusion processes were identified as the main mechanisms controlling the rate of the dye sorption.

Chemical tracers as indicator of human fecal coliforms at storm water outfalls

Indicators to distinguish between fecal coliforms of human and animal origin were investigated in water from storm sewer outfalls to a coastal lake during wet and dry weather. The ratio of fecal coliform relative to fecal streptococci count was used as the microbiological indicator. Concentrations of human-activities originated caffeine, anionic surfactant, fluoride, and fluorescence whitening agent (FWA) were used as chemical indicators. The ratio of fecal coliform to fecal streptococci ranged from 0.2 to 3.0, during wet weather making it difficult to interpret the origin of fecal pollution. However, concentrations of caffeine, anionic surfactant, fluoride, and FWA in storm water outflow during wet weather were much higher than those in the lake water during dry weather, indicating the presence of human waste at storm water outfall. Strong correlation between fecal coliform counts and chemical parameter values further indicated the human contribution to the fecal coliform count. In addition, a strong correlation among the chemical parameters suggested that only one of them is needed as chemical tracer to detect the presence of human input.

Analysis of ecdysteroids by micellar electrokinetic chromatography with on-line preconcentration

In order to enhance the UV detection sensitivity, an application study of an on-line preconcentration technique for micellar electrokinetic chromatographic (MEKC) was carried out. The simultaneous determination of four test ecdysteroids, 20-hydroxyecdysone, ajugasterone C, polypodine B and ponasterone A has been investigated by using the normal stacking mode in MEKC with UV detection. The effects of anionic surfactant composition and concentration, the applied voltage, the pH buffer, the kind and the amount of organic solvent and the injection time on the analyte resolution were evaluated. The optimised conditions for the separation involved the use of a 50 mM borate as the running buffer containing 50 mM of a mixture of sodium dodecyl sulphate (SDS) and sodium cholate (SC) in the ratio of 1:1 together with a concentration of 10% (v/v) of 2-PrOH at pH 9.0. Hydrodynamic injection of 12 s at 50 mbar and separation voltage of 20 kV at temperature of 20 °C were employed. These conditions allowed a repeatability separation within 21 min. Concentration detection limit for the neutral analytes studied improve about an order of magnitude. The method was also applied to the determination of ecdysteroids in a real sample.

Binding of counterions by micelles of ionic surfactants

The dependence of the concentration of free counterions on the overall concentration of an ionic surfactant is analyzed in terms of the quasi-chemical theory of micellization. The degree of binding of counterions by micelles of sodium dodecyl sulfate is determined from the results of potentiometric measurements performed using a sodium-selective electrode. It is disclosed that experimental and theoretical data are in satisfactory agreement, provided that the model used allows for the association of surface-active ions in a solution, with this association reducing the average coefficient of sodium dodecyl sulfate activity in an intermicellar medium.

Large scale application of membrane bioreactor technology for the treatment and reuse of an anionic surfactant wastewater

The treatment of an anionic surfactant rich wastewater by a powerful Citrobacter braakii strain was investigated at large scale. This bacterium was inoculated into a 4.5 m 3 continuous stirred tank reactor (CSTR) without a membrane. At volumetric loading rates ranged between 0.44 and 0.96 g COD l −1 d −1, a weak C. braakii population density was observed in the reactor which results in slow anionic surfactants degradation kinetics. The augmented bacterium was diluted and replaced by protozoa and other forms of bacteria after a prolonged experience run. The CSTR was then coupled to a cross-flow ultrafiltration membrane. This allowed complete biomass recycling and partially retention of the surfactants in the reactor. C. braakii became again dominant in the medium. At volumetric loading rates of 0.6–1.5 g l −1 d −1, the anionic surfactant concentration in the permeate varied from 0 to 40 mg l −1 with a mean value of 18 mg l −1. After 2 months of running, mixed liquor volatile suspended solids (MLVSS) in the reactor increased from 0.71 to 5.92 g l −1 and the permeate-flux slightly decreased from 28.75 to 23.75 l h −1 m −2. The reclaimed water could be reused either for the washing of the material and soil, and to irrigate the parkland of the factory.

Capillary Rise Infiltration into Soils and Porous Media as Affected by an Anionic Surfactant Concentration

Capillary Rise Infiltration into Soils and Porous Media as Affected by an Anionic Surfactant Concentration

Filtration characteristics of a fibrous filter pretreated with anionic surfactants for monodisperse solid aerosols

This study elucidates the effects of using an anionic surfactant-pretreated filter as an electret filter on the aerosol penetration. Anionic surfactants (sodium oleate, SO; sodium dodecyl sulfate, SDS) were used to pretreat polypropylene fibrous filters to make them negatively charged. Various factors, including the particle size (0.05– 0.5 μ m ), the aerosol charge state (Boltzmann-equilibrium charge, neutral and singly charge), the face velocity (0.1, 0.3, 0.5 and 1.0 m / s ), the species of aerosol (sodium chloride, NaCl and aluminum oxide, Al 2 O 3 ), the relative humidity (RH 30% and 70%) and the concentration of surfactant (0.01, 0.05 and 0.08 M) were considered to evaluate their effects on the aerosol collection characteristics. Experimental results from our study demonstrate that the aerosol penetrations through anionic surfactant-pretreated filters (ASPFs) were lower than through the untreated filter. The 0.3 μ m -aerosol penetrations through an untreated, 0.01, 0.05 and 0.08 M SO-pretreated filters with Boltzmann-equilibrium charged aerosol were about 78%, 53%, 45% and 40%. The penetration of 0.3- μ m aerosol of 0.01, 0.05 and 0.08 M SDS-pretreated filters with Boltzmann-equilibrium charged aerosol were, 62%, 58% and 51%. Pretreating the filter with anionic surfactant did not change the structure of the filter and the mechanical capture force. The electric field measured by an electrofieldmeter of the ASPFs was larger than that of untreated filter obviously. These findings imply that pretreatment with anionic surfactant made the filters charged. The surface charge of the ASPFs increased with the anionic-surfactant concentration. The increase of the collection efficiency of the ASPFs is in the range of 5–30%, and that depends on the aerosol size and surfactant concentration. Comparing between the aerosol penetration through the ASPFs with singly charged aerosol and that through the untreated filter with neutral aerosol indicates that the penetration through the ASPFs with singly charged aerosol decreases by a factor of 1.3–12.5. In contrast with the penetration through the ASPFs to that through the untreated filter with neutral aerosol, the penetration reduction factor of the ASPFs is in the range of 1.1–1.9. As the results shown, the Coulombic capture force is dominant for the smaller aerosol ( < 0.1 μ m ) and the dielectrophoretic capture mechanism works at larger aerosol size ( > 0.2 μ m ) . Additionally, the penetrations through the ASPFs increased with the face velocity. ASPFs performed better when the tested aerosol had a larger dielectric constant ( k ) such as the penetration through 0.05 M SO-pretreated filter with 0.3 μ m Al 2 O 3 aerosol ( k = 9.6 ) was 47% and that with NaCl aerosol ( k = 5.9 ) was about 53%. RH has no effect on the aerosol penetration through the ASPFs.

Surfactants in Atmospheric Aerosols

The concentration and characteristics of anionic and cationic aerosol surfactants at a range of locations were determined as methylene blue active substances (MBAS) and ethyl violet active substances (EVAS) for anionic surfactants and as disulfine blue active substances (DBAS) for the cationic surfactants. Results showed that the anionic surfactants (in the pmol m(-3) range) dominated the concentration of surfactant in atmospheric aerosols. The concentration of both MBAS and EVAS is typically higher on the finer aerosol fractions. Further study on the aerosols found both MBAS and EVAS had the ability to reduce the surface tension of aqueous extracts of the aerosol. MBAS were more readily destroyed on exposure to a high intensity of UV light than were EVAS. The source of these seemingly ubiquitous compounds is not clear, but we note that anionic surfactants are easily derived from degraded or oxidized soots, especially that from diesel engines.

Estimation of critical micelle concentration of anionic surfactants with QSPR approach

The hydrophobic–hydrophilic segment geometries of 98 anionic surfactants were fully optimized and calculated by ab initio RHF/6-31G(d), quantum chemical data such as the charge density, the energy of molecular orbital and the dipole moment were obtained. The anionic surfactants employed including sodium alkyl sulfates, sodium alkyl sulfonates, sodium alkyl benzenesulfonates, and potassium alkyl carboxylates with a wide variety of hydrophobic structures. Based on one constitutional descriptor and two quantum chemical descriptors, a significant quantitative structure–property relationship (QSPR) model for the critical micelle concentration of anionic surfactants was obtained by using the multiple linear regression technique. The good correlation coefficient of R 2 (0.980) and cross-validation correlation coefficient R cv 2 (0.978) indicate the excellent capability and stability of the regression equation developed. It was found out that the total atom number ( N T) in the surfactant hydrophobic–hydrophilic segment plays a major role in the model, the dipole moment ( μ) of the surfactant segment and the max net atomic charge on C atom ( Q C-max) in the surfactant segment are also important. Nine anionic surfactants were employed to test the model developed, the calculated critical micelle concentration was consistent with the experimental one.

Synthesis of 1D Cu 2S with tailored morphology via single and mixed ionic surfactant templates

Using a simple surfactant-assisted pathway, various shapes of crystalline copper sulphide (Cu 2S) such as micro and submicron particles, nanorods and nanowires have been synthesized. This type of shape tailoring was possible by varying the molar ratio of cationic and anionic surfactants. Under appropriate condition, uniform nanowires were obtained. This was revealed from scanning and transmission electron microscopy. XRD analysis confirms the formation of monoclinic Cu 2S. The optical band gap determined from reflectance spectra was found to have values within the range of 1.22–1.24 eV. The aspect ratio of the nanorods was found to increase with the increase of the concentration of anionic surfactant.

Critical Micellization Concentration of Ionic Surfactants: Comparison of Theoretical and Experimental Results

Theoretically calculated critical micellization concentration (CMC) of an ionic surfactant and the corresponding experimental value (CMC0) are compared. The CMC values are calculated within the framework of the quasi-chemical model. The CMC0 values are determined by the extrapolation of two linear parts of a dependence of a solution property on surfactant overall concentration. These parts of the aforementioned dependences correspond to the premicellar and micellar regions. The difference between CMC and CMC0 is found to be negligible and comparable with the measurement error. Cases in which this difference must be taken into account when estimating the properties of micellar solutions are discussed. It is shown that the micellization constant Kc of surfactant molecules can be calculated from the data on CMC0.

Rapid demulsification of dense oil-in-water emulsion by low external electric field: I. Experimental evidence

Rapid demulsification of dense oil-in-water (O/W) emulsions has been found to be induced by applying a low electric field of the order of 1–10 V/cm. The demulsification simultaneously takes place over the entire space between two electrodes. Dilute O/W emulsions are demulsified only near an electrode after being condensed by electrophoresis of the droplets, which indicates that the mutual contact of oil droplets through thin water layers is necessary for the rapid demulsification. Increase of the concentration of electrolyte accelerates the demulsification, whereas increase of the concentration of an ionic surfactant retards the demulsification. O/W emulsions stabilized with a nonionic polymer surfactant are not demulsified. Water-in-oil (W/O) emulsions are not demulsified even the chemical components are the same as those of the O/W emulsion. Application of an alternating electric field with the frequency higher than 10 kHz does not cause the demulsification. All this evidence strongly suggests that the applied low electric field causes the rearrangement of surface charges on oil droplets, which results in the reduction of the height of an energy barrier for the coalescence of the droplets.

In vitro study on the interaction of mechanism of tricyclic compounds with bovine serum albumin

The mechanism of interaction of five phenothiazine drugs with bovine serum albumin has been investigated using fluorescence spectroscopy, circular dichroism and equilibrium dialysis methods. It was found that the phenothiazine ring common to all drugs makes major contribution to interaction. However, the nature of alkylamino group at position 10 influences the protein binding significantly. Binding affinities could be related to parachor values of drugs. Stern–Volmer plots indicated the presence of static component in the quenching mechanism. Results also showed that both tryptophan residues of protein are accessible to drug molecules. The high magnitude of rate constant of quenching indicated that the process of energy transfer occurs by intermolecular interaction forces and thus drug-binding site is in close proximity to tryptophan residues of BSA. Binding studies in presence of hydrophobic probe, 8-anilino-1-naphthalein-sulphonic acid showed that there is hydrophobic interaction between drugs and the probe and they do not share common sites in BSA. Fluorescence intensity data in the presence of additives showed that hydrophobic interactions play a significant role. Small decrease in critical micellar concentration of anionic surfactant, sodium dodecyl sulfate in the presence of drugs showed that the ionic character of drugs also contribute to binding. Thermodynamic parameters obtained from data at different temperatures showed that the binding of phenothiazine drugs to BSA involve hydrophobic bonds predominantly. The CD spectrum of BSA in presence of drugs shows that binding of drugs leads to change in the helicity of the protein. The binding of these drugs to BSA based on dialysis experiment has been characterized by association constant ( K) and the number of binding sites ( n).

Tl(III) initiated polymerization of methyl methacrylate in micellar phase

AbstractThe polymerization kinetics of methyl methacrylate (MMA) was studied, using Tl(III)‐cyclohexanone (CH) redox system as initiator, in the presence of emulsifier [i.e., sodium dodecyl sulfate (SDS), cetyltrimethylammonium bromide (CTAB), and thallium triacetate (TX‐100)] over a temperature range of 25–45°C. The effect of various concentrations of MMA, Tl(III), cyclohexanone, H+, and varying ionic strengths on the rate of polymerization, rate of Tl(III) consumption (−RTl), and the percentage of monomer conversion were examined in the presence of 0.015M SDS. The kinetic results of polymerization in the absence and presence of 0.015M SDS were compared in terms of overall activation energy (Ea) for the process. The viscosity‐average molecular weight (MV) of the polymers, obtained in the presence of varying concentrations of anionic surfactant (SDS), was also determined. © 2004 Wiley Periodicals, Inc. J Appl Polym Sci 92: 2480–2485, 2004

Gold Electrode Modified with a Self‐Assembled Monolayer of 11‐Amino‐1‐undecanethiol Hydrochloride for the Determination of Anionic Surfactants

ABSTRACT Effect of anionic surfactants on the cyclic voltammetric response of Fe(CN)6 3− at a gold electrode modified with self‐assembled monolayer (SAM) of 11‐amino‐1‐undecanethiol hydrochloride was examined. As the concentration of anionic surfactants increases, the currents of [Fe(CN)6]3− reduction decreases and cyclic voltammograms become irreversible. The currents of [Fe(CN)6]3− reduction depended on the concentration of anionic surfactants in the 10−6 M range.

A Comprehensive Experimental Investigation of the Methyl Methacrylate/Butyl Acrylate/Acrylic Acid Emulsion Terpolymerization

In the present study a comprehensive experimental investigation on the batch and semi‐batch emulsion terpolymerization of methyl methacrylate/butyl acrylate/acrylic acid (MMA/BuA/AA) is reported. Batch experiments were carried out in a fully automated pilot‐scale reactor system to analyze the effect of polymerization temperature, anionic surfactant and initiator concentrations on the polymerization rate, average particle size, copolymer composition and glass transition temperature of the polymer. In addition, a series of semi‐batch experiments were performed under monomer starved conditions to assess the effect of seven process variables, (e.g., concentrations of anionic, nonionic surfactants and initiator, polymerization temperature, agitation rate, impeller type and addition time of initiator/pre‐emulsion mixture) on the polymerization rate, average particle size, copolymer composition, glass transition temperature and MWD of the polymer.

Agglomerate flotation of fine oxide particles

This paper presents experimental data on using both flocculants and surfactants for aggregation and flotation of fines. The work has been performed with water suspensions of two oxides, ZnO and MgO. Conventional flotation collectors (sodium oleate (SOL), sodium dodecyl sulphate (SDS) and cetyltrimethylammonium bromide (CTAB)) were used. Commercial high molecular weight polymers (MAGNAFLOC 1440, MAGNAFLOC E-10 and MAGNAFLOC 351) were the flocculants used. Adsorption isotherms of surfactants adsorbing onto the two oxides were determined at natural pH. Adsorption density was the greatest with sodium oleate. Zeta potential measurements indicated that addition of the cationic surfactant caused a positive increase of the zeta potential. The positive zeta potential of MgO decreased with increased anionic surfactant concentration. A decrease in stability indicated that the ZnO suspension pretreated with anionic surfactants caused the formation of larger flocs when the cationic flocculant (MAGNAFLOC 1440) was added. Similar observations were obtained for a MgO suspension pretreated with anionic surfactants and reacted with the nonionic flocculant, MAGNAFLOC 351. The negative charged collector (SDS) appears to be good collector for ZnO floc flotation when hydrophobic flocs are created by the combination of SDS and either cationic or nonionic flocculants.

Surface Remobilization of Gas Bubbles in Polymer Solutions Containing Surfactants

In a previous study, Carreau et al. [ Rheol. Acta 13, 477 (1974)] did not observe a discontinuity in their graphical representation of velocity as a function of volume (0.1–10 cm 3) for air bubbles using a 0.5 wt% polyacrylamide solution in a 20/80 glycerin/water mixture. In this study, we report that such discontinuity is occurring when smaller volumes are used. Furthermore, we also show that, for concentrations of an ionic surfactant (sodium dodecyl sulfate) above the critical association concentration of the system, polymer–surfactant association can lead to possible surface remobilization and to the elimination of such discontinuity.