Solubility of Ethane,Propane, and Butane in Aqueous Solutions of Sodium Dodecyl Sulfate

The solubility of ethane, propane, and butane under standard conditions in aqueous micellar solutions of sodium dodecyl sulfate with the salt concentration from 0. 025 to 0. 3 M was studied. The methylene group increment of the Gibbs energy of solubilization in the systems hydrocarbons (C₂–C₄)-sodium dodecyl sulfate was calculated; its value, −3.7 kJ mol⁻¹, is close to that in solutions with addition of 0.1 M NaCl. The thermodynamic cycle of methylene group increments of the Gibbs energies of solution of hydrocarbons in water and micellar solutions of surfactants is discussed.__________Translated from Zhurnal Obshchei Khimii, Vol. 75, No. 1, 2005, pp. 36–38.Original Russian Text Copyright © 2005 by Mirgorod.     

Metal Ion Buffer Systems for Ionometry in Water-Ethanol Mixtures and Micellar Medium of Sodium Dodecyl Sulfate

The concentration dissociation constants of nitrilotriacetic acid and the concentration stability constants of Cd(II) complexes with the nitrilotriacetic acid anion in water-ethanol mixtures and of Cu(II) and Cd(II) complexes with o-phenanthroline and 2,2′-bipyridine in micellar solutions of sodium dodecyl sulfate were determined potentiometrically. Based on the concentration constants determined, Cd²⁺ and Cu²⁺ buffer solutions were developed for calibration of a Cd²⁺-selective electrode in water-ethanol mixtures and Cd²⁺ and Cu²⁺-selective electrodes in micellar solutions of sodium dodecyl sulfate within the ranges pCu 9.7–13.5 and pCd 7.5–11.8.__________Translated from Zhurnal Prikladnoi Khimii, Vol. 78, No. 2, 2005, pp. 273–278.Original Russian Text Copyright © 2005 by Chernysheva, Loginova, Bazilyanskaya.     

Thermodynamics of inclusion complex formation of β-cyclodextrin with a variety of surfactants differing in the nature of headgroup

The inclusion complexation of β-cyclodextrin with various surfactants, possessing the same alkyl chain length but differing in the hydrophilic headgroup, was investigated by isothermal titration microcalorimetry. Sodium dodecyl sulfate, sodium dodecyl sulfonate, dodecyltrimethylammonium bromide and dodecyl(dimethyl)amine oxide were investigated. The major aim of this study was to elucidate the effects of temperature and the nature of the headgroup on the complex formation. Thermometric titrations were effected between the temperatures (288 and 348) K. The results provided the stoichiometry, the equilibrium constant and the reaction enthalpy of complexation. Changes in Gibbs energy, entropy and van’t Hoff enthalpy were additionally calculated.     

Condensation of <Emphasis Type="Italic">p</Emphasis>-Dimethylaminocinnamaldehyde with Aniline and Substituted Anilines in Micellar Media

Optimal conditions were found for the reactions of aniline and its hydroxy-, carboxy-, methyl-, and nitro-substituted derivatives with p-dimethylaminocinnamaldehyde in the presence of sodium dodecyl sulfate micelles in the pH range 1–6. A correlation was revealed between the optimal pH value pK _a of aromatic amines. The reaction in the model system aniline-p-dimethylaminocinnamaldehyde-sodium dodecyl sulfate in micelles formed by anionic surfactants is accelerated more than 1000-fold due to increased concentration of the reactive species in sodium dodecyl sulfate micelles.__________Translated from Zhurnal Obshchei Khimii, Vol. 75, No. 2, 2005, pp. 288–294.Original Russian Text Copyright © 2005 by Doronin, Chernova, Gusakova.     

Investigation of the state of 8-hydroxyquinoline in aqueous sodium dodecyl sulfate solutions

The influence of sodium dodecyl sulfate on the dissociation of protonated 8-hydroxyquinoline in aqueous solutions is investigated by potentiometric titration at 293 K. The constants of direct binding of 8-hydroxyquinoline with the monomers and micelles of sodium dodecyl sulfate are determined by the computer simulation of the most probable processes. The role of electrostatic and hydrophobic interactions in the studied system is discussed.__________Translated from Kolloidnyi Zhurnal, Vol. 67, No. 2, 2005, pp. 231–234.Original Russian Text Copyright © 2005 by Ramenskaya, Vladimirova.     

Solvatochromic studies of interactions between surfactants and poly(N-substituted acrylamide)s

Interactions between poly(N-substituted acrylamide)s and surfactants, such as sodium dodecyl sulfate (SDoS) and sodium decyl sulfate (SDeS), in aqueous solutions were investigated using a solvatochromic probe. The polymers used were poly(N,N-dimethylacrylamide) (PDMA), poly(N-isopropylacrylamide) (PIPA), poly(N-acryloylpyrrolidine) (PAPR), and poly(vinylpyrrolidone) (PVPy) for comparison. They were labeled with pyridinium dicyanomethylide chromophore as a solvatochromic probe, and the changes in the microenvironment polarity of the polymer upon association with surfactant micelles were investigated by monitoring the λ_max in the absorption spectra of the probe molecule. It was found that the Gibbs free energy of micelle stabilization by polymer complexation for SDoS is 7.6, 4.1, and 2.2 kJ mol⁻¹, and for SDeS 5.1, 2.9, and 0.8 kJ mol⁻¹ with PIPA, PAPR, and PDMA, respectively. These results indicate that the complexation between polymer and surfactant is influenced not only by the alkyl-chain length of the surfactant, but also by the polymer side groups.     

Effects of Cs and Na ions on the interfacial properties of dodecyl sulfate solutions

The competitive binding of counterions to anionic dodecyl sulfate ions in aqueous solutions of cesium dodecyl sulfate (CsDS) and sodium dodecyl sulfate (SDS) mixtures, which significantly influences the critical micelle concentration (cmc) and surface (or interfacial) tension of surfactant solutions, was investigated. The cmc and degree of counterion binding were obtained through electrical conductivity measurements. The curve of cmc versus the mole fraction of CsDS in the surfactant mixture was simulated by Rubingh's equations, which enabled us to estimate the interaction parameter in micelles (W _R) based on the regular solution approximation. The curve-fitting exhibited a slightly negative value (W _R=−0.1), indicating that the mixing (SDS+CsDS) enhances micelle formation owing to a greater interaction between surfactant molecules and counterions than in pure systems (SDS). On going from SDS, SDS:CsDS(75:25), SDS:CsDS(50:50), SDS:CsDS(25:75) to CsDS, interfacial tension at the hexadecane/surfactant-solution interface showed a negative deviation from the mixing rule (interaction parameter in adsorbed film W _A=−0.38), indicating the replacement of Na⁺ bound to anionic dodecyl sulfate by Cs⁺ ions owing to the stronger interaction between the Cs⁺ and the dodecyl sulfate ions. Droplet sizes of emulsion formed with hexadecane and aqueous dodecyl sulfate solutions were investigated using the light scattering spectrophotometer. The higher binding capacity of Cs⁺, having a smaller hydrated ionic size than Na⁺, also resulted in a negative deviation in emulsion droplet size in mixed systems. Received: 10 May 2000/Accepted: 11 August 2000     

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.__________Translated from Kolloidnyi Zhurnal, Vol. 67, No. 2, 2005, pp. 213–217.Original Russian Text Copyright © 2005 by Podchasskaya, Usyarov.     

Analysis of neutral and sialylatedN-liked oligosaccharides by micellar electrokinetic capillary chromatography with addition of a divalent cation

Summary Micellar electrokinetic capillary chromatography (MECC) has been investigated as an alternative mode of analyzing oligosaccharides released from glycoproteins. The influence on the separation of experimental parameters such as the concentrations of surfactant and electrolyte and the addition of divalent cations was examined. Solubilization, of neutral oligosaccharides by micelles was demonstrated whereas for the sialylated oligosaccharides the electrophoretic mobility remained the predominant factor. The addition of Mg⁺⁺ to sodium dodecyl sulfate (SDS)solutions provided an effective means of enhancing the selectivioty of the separation through both an increase of the time window and the differential complexation of carbohydrate with this divalent cation.     

Interactions between a surfactant and cavitand in water blur distinctions between host and guest

The complexation of a water-soluble cavitand and sodium dodecyl sulfate micelles is studied using NMR diffusion ordered spectroscopy.     

Effect of a Weak Electrolyte on the Critical Micellar Concentration of Sodium Dodecyl Sulfate

The critical micellar concentration of sodium dodecyl sulfate is strongly altered bytris(hydroxy-methyl)methylammonium ions. The effect of buffer solutions containing this weak electrolyte as the counterion source has been studied using various concentrations of the acid–base system as well as modifying the pH. Results show that counterion concentrations ranging from 0 to 340 × 10⁻³M induce an appreciable diminution of the critical micellar concentration from 8 to 0.7 × 10⁻³M. The analysis of data suggests that the critical micellar concentration of sodium dodecyl sulfate depends on the concentration of weak electrolytes in a way very similar to that of strong electrolytes.     

Complexation of plutonium(IV) with sulfate at variable temperatures

The complexation of plutonium(IV) with sulfate at variable temperatures has been investigated by solvent extraction method. A NaBrO₃ solution was used as holding oxidant to maintain the plutonium(IV) oxidation state throughout the experiments. The distribution ratio of Pu(IV) between the organic and aqueous phases was found to decrease as the concentrations of sulfate were increased. Stability constants of the 1:1 and 1:2 Pu(IV)-HSO₄ ⁻ complexes, dominant in the aqueous phase, were calculated from the effect of [HSO₄ ⁻] on the distribution ratio. The enthalpy and entropy of complexation were calculated from the stability constants at different temperatures using the Van’t Hoff equation.     

Formation of chitosan—surfactant complexes in aqueous-alcohol media

Russian Chemical Bulletin - The complexation of chitosan and anionic surfactant, sodium dodecyl sulfate (DDS), in aqueous-alcohol media with a variable content of an organic cosolvent (methanol,...     

Analysis of salicylic acid based on the fluorescence enhancement of the As(III)-salicylic acid system

A new, simple and sensitive spectrofluorimetric method for the determination of salicylic acid (λ_ex = 315 nm, λ_em = 408 nm) using As(III) as a sensitizing reagent has been investigated by measuring the increase of fluorescence intensity of salicylic acid due to the complexation of As(III)-salicylic acid in presence of sodium dodecyl sulfate (SDS) 10⁻³ M. Under optimum conditions, a significant relationship was obtained between the fluorescence intensity and salicylic acid concentration. A linear calibration curve was obtained in the range 13.8-13812 μg l⁻¹ with product-moment correlation coefficient (R) 0.99985 and detection limit 4.2 μg l⁻¹. The R.S.D. is 2.35% (n = 5).The method was applied successfully to the determination of salicylic acid in human serum.     

Study of Six Polycyclic Aromatic Hydrocarbons by Chemical Deoxygenation Microemulsion-Stabilized Room Temperature Phosphorimetry

Six polycyclic aromatic hydrocarbons (PAHs) are studied by chemical deoxygenation microemulsion-stabilized room temperature phosphorimetry with sodium sulfite as an oxygen scavenger and thallous nitrate as a heavy atom perturber in sodium dodecyl sulfate medium. Several factors influencing room temperature phosphorescence such as the concentration of sodium dodecyl sulfate, the heavy atom concentration, the pH, and the concentration of sodium sulfite are discussed and the quenching effect of NO₂⁻on room temperature phosphorimetry of PAHs was compared in the microemulsion and micelle media.     

Synthesis of Monodisperse Polystyrene Particles in the Presence of Sodium Dodecyl Sulfate and Carboxyl-containing Initiator

Emulsion polymerization of styrene in the presence of an anionic surfactant, sodium dodecyl sulfate, in a concentration close to the critical micellization concentration, was studied, as influenced by the pH of the initial reaction mixture and the content of the carboxyl-containing azoinitiator.__________Translated from Zhurnal Prikladnoi Khimii, Vol. 78, No. 6, 2005, pp. 1029–1033.Original Russian Text Copyright © 2005 by Men’shikova, Evseeva, Shabsel’s, Balanina, Sirotkin, Ivanchev.     

Evaluation of the stability constants of uranyl association complexes with chloride, fluoride, bromide, and sulfate anions in solutions of constant ionic strength

Use of ascorbic acid as an indicator for the determination of the classical formation constants of uranyl association complexes with some ligand anions is studied in solutions of 0.05 ionic strength. The results enable the establishment of a sequence of complexation for the anions investigated vis., fluoride, chloride, bromide, and sulfate. This is as follows in order of decreasing complexing power on uranium: F⁻ > SO₄²⁻ > Cl⁻ > Br⁻. The validity of using the indirect ascorbate method for the determination of classical equilibrium constants is established for the uranyl sulfate complex by comparison of the K values with those obtained by the direct spectrophotometric procedure using the continuous variation method. Both procedures indicate the formation of a 1:1 uranyl sulfate complex.     

Electrochemical surface plasmon resonance investigation of dodecyl sulfate adsorption to electroactive self-assembled monolayers via ion-pairing interactions

The redox-induced assembly of amphiphilic molecules and macromolecules at electrode surfaces is a potentially attractive means of electrochemically modulating the organization of materials and nanostructures on solid substrates via ion-pairing interactions or charge-transfer complexation. In this regard, we have investigated the potential-induced adsorption and aggregation of dodecyl sulfate, a common anionic surfactant, at a ferrocenylundecanethiolate (FcC11SAu) self-assembled monolayer (SAM)/aqueous solution interface by electrochemical surface plasmon resonance (ESPR) spectroscopy. The surfactant anions adsorb onto the electroactive SAM by specific ion-pairing interactions with the oxidized ferricinium species. The ferricinium charge density (QFc+) obtained by cyclic voltammetry and surface coverage measured by SPR indicate that the dodecyl sulfate forms an interdigitated monolayer, where half of the surfactant molecules have their sulfate headgroups paired to the surface and half have their headgroups exposed to the aqueous solution. The surface coverage of dodecyl sulfate was found to depend on both the ferricinium surface concentration and the surfactant aggregation state in solution. A maximum coverage of dodecyl sulfate on the ferricinium surface is obtained below the critical micelle concentration (cmc), in contrast to dodecyl sulfate adsorption to SAM surfaces of static positive charge. This marked difference in adsorption behavior is attributed to the dynamic generation of ferricinium by potential cycling and the specific nature of the ion-pairing interactions versus pure electrostatic ones. The results presented point to a new way of organizing molecules via electrical stimulus.     

Spectrophotometric and calorimetric studies of Np(V) complexation with sulfate at 10–70°c

Sulfate, one of the inorganic constituents in the groundwater of nuclear waste repository, could affect the migration of radioactive materials by forming complexes. Spectrophotometric and microcalorimetric titrations were performed to identify the Np(V)/sulfate complex and determine the equilibrium constants and enthalpy of complexation at 10–70°C. Results show that the complexation of Np(V) with sulfate is weak but slightly enhanced by the increase in temperature. The complexation is endothermic and becomes more endothermic with the increase in temperature. The enhanced complexation at elevated temperatures is due to the increasingly larger entropy of complexation that exceeds the increase in enthalpy, indicating that the complexation of Np(V) with sulfate is entropy-driven.     

Physicochemical Properties of Aqueous Solutions of Binary Mixtures of Lignin Derivatives and Sodium Dodecyl Sulfate

Physicochemical properties of aqueous solutions of binary mixtures of lignosulfonates and sodium dodecyl sulfate were studied. Introduction of sodium dodecyl sulfate into solutions of high-molecular-mass lignosulfonates at certain ratios causes macrophase separation of the systems with the formation of loose precipitates. A synergistic effect of a decrease in the surface tension is observed in the mixed solutions. This effect increases with increasing lignosulfonate molecular mass and temperature. The revealed relationships are caused by hydrophobic interactions of hydrocarbon radicals of sodium dodecyl sulfate with hydrophobic segments of lignosulfonate polymer chains with the formation of micellar associates. Aqueous solutions of binary mixtures of lignosulfonates (с_LS ≥ 0.2 g dm^–3) and sodium dodecyl sulfate (с_DSNa ≥ 0.08 g dm^–3) can be recommended for use as surfactant formulations for high-temperature autoclave leaching of polymetal ores.