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.     

Effects of cationic micelles on fluorescence of indole and indolecarboxylic acids. Analytical determinations

The effect of cationic micelles of benzyldimethylhexadecylammonium chloride and hexadecyltrimethylammonium bromide on the fluorescence spectra of indole and its carboxylic derivatives were determined. The larger solute-micelle binding constants were provided by benzyldimethylhexadecylammonium chloride, ranging from 0.10·10⁵ and 2.15·10⁵ M ^–1 for indole-5-carboxylic and indole-2-carboxylic acid, respectively. The determination of indole-4-carboxylic acid with a detection limit of 1.0 ng ml^–1, in the presence of the 3-and 5-substituted derivatives, shows the analytical potential of the synchronous spectrofluorimetry combined with the enhancement effects caused by micellar media.     

Extraction by reversed micelles of triton N-42 for the spectrophotometric determination of cetyltrimethylammonium bromide

Micellar preconcentration of 1 : 2 associates of Bromophenol Blue with cetyltrimethylammonium bromide is proposed to improve the procedure for the spectrophotometric determination of cationic surfactants. The preconcentration procedure involves quantitative extraction by reversed micelles of Triton N-42 in decane followed by the decomposition of the micellar solution with chloroform. The loss of 10^–7–10^–5 M cetyltrimethylammonium bromide in 5–100-fold preconcentration was not supported by the added-found method (RSD = 3–5%). The determination limit for cetyltrimethylammonium bromide is 2 × 10^–7 M.Translated from Zhurnal Analiticheskoi Khimii, Vol. 60, No. 1, 2005, pp. 17–21.Original Russian Text Copyright © 2005 by Demidova, Bulavchenko.     

Determination of propazine by differential pulse polarography in micellar and emulsified media

An electroanalytical study of the herbicide propazine's reduction process in micellar solutions and oil-in-water emulsions is reported. The anionic surfactant sodium pentanesulphonate was chosen as the most suitable. The differential pulse polarograms of micellar solutions had two reduction peaks below pH 2.0, whereas only one peak was obtained above pH 2.O. Ethyl acetate was chosen as the organic solvent to form propazine emulsions. Unlike in micellar solutions, the DPP polarograms of propazine emulsions showed only one peak even at pH < 2.0, suggesting that propazine hydrolysis was hindered in the emulsified medium. The limiting current is diffusion-controlled and the electrode process is irreversible. Propazine can be determined by differential pulse polarography over the 1.0 × 10^–1 – 1.0 × 10^–1moll^–1 and 1.0 × 10^–15 – 4.0 × 10^–1 moll^–1 concentration ranges and the limit of detection was 2.8 × 10^–1 moll^–1. Of the potential interferents simazine, methoprotryne and terbutryn (alls-triazines), thiram (a dithiocarbamate), dinoseb (nitrophenolic), and heptachlor (chlorinated cyclo-diene herbicide), only the first two were significant (10% error for equimolar concentrations). The method was applied to the determination of propazine in spiked drinking water. At a concentration level of 2.0 × 10^–1 moll^–1 a recovery of 94 ± 6% was obtained, after tenfold concentration on Sep-Pak.     

Excess Thermal Expansion Factors of Polar Mixtures and Aqueous Solutions

Excess thermal expansion factor of non-polar mixtures is the order of 10^–6 K^–1 and within an experimental error. On the other hand, those of polar mixtures and aqueous solutions are very large and the order of 10^–5 K^–1, up to the order of 10^–4 K^–1 in an extreme case. The excess thermal expansion factors express well the excesses of entropy volume cross fluctuation and enthalpy volume cross fluctuation estimated from thermal expansion factor and molar volume. Those of aqueous solutions are, however, reduced by small molar volume of water.This revised version was published online in November 2005 with corrections to the Cover Date.     

Determination of Enalapril by Stripping Voltammetry at a Mercury Film Electrode

A procedure was developed for determining 4.0 × 10^–6 to 2.6 × 10^–3 M enalapril in model solutions and blood serum by anodic stripping voltammetry at a mercury film electrode.__________Translated from Zhurnal Analiticheskoi Khimii, Vol. 60, No. 5, 2005, pp. 495–498.Original Russian Text Copyright © 2005 by Gusakova, Ivanovskaya.     

Potentiometric investigations of some catechol derivatives of scandium

The equilibrium reactions of scandium(III) with some triprotic catechol derivatives (H₃L) were studied. The selected ligands that are 2,3-dihydroxybenzoic acid (2,3-DHBA), 3,4-dihydroxybenzoic acid (3,4-DHBA), 3.4-dihydroxyhydrocinnamic acid (3,4-DHHCA), and 3,4-dihydroxyphenylacetic acid (3,4-DHPA) were investigated in aqueous solution by means of potentiometry in 0.1 M ionic medium at 25°C. The stability constants are reported for the ScL and ScL(H₂L)^– mononuclear complexes. 2,3-DHBA can bind to Sc³⁺ ion strongly and the salicylate mode (COO^–, O^–) is effective over the acidic pH range. But in higher pH range, 3,4-DHBA, 3,4-DHHCA, and 3,4-DHPA act more efficiently through catecholate groups (O^–, O^–).Translated from Koordinatsionnaya Khimiya, Vol. 31, No. 3, 2005, pp. 229–233.Original Russian Text Copyright © 2005 by Türkel, Özer.This revised version was published online in April 2005 with a corrected cover date.This revised version was published online in April 2005 with a corrected cover date.     

Determination of trace europium(III) based on a new fluorescence enhancement system of europium(III) with N,N′-<Emphasis Type="Italic">bis</Emphasis>-(4-N-aminothiourea-2-amylidene)-4,4′-diaminodiphenyl sulfone by EDTA or alumin in N,N-dimethylformamide

A new bis-Schiff base ligand, N,N-bis-(4-N-aminothiourea-2-amylidene)-4,4-diaminodiphenyl sulfone (ARADS), was synthesized. The solutions of its complex with Eu³⁺ in DMF can emit the intrinsic fluorescence of Eu³⁺. The fluorescence intensity of the complex was enhanced 20–30-fold in the presence of EDTA (or alum). The influence of seven kinds of solvents (DMF, CH₃CN, THF, acetone, CH₃OH, C₂H₅OH, and DMSO) on the intensity of fluorescence was studied. The results showed that the Eu³⁺-ARADS-EDTA (or alum) system emits its strongest fluorescence in DMF. Thus, the system can be used to develop a new method for the determination of europium(III). The excitation and emission wavelengths are 395 and 615 nm, respectively. Under optimal conditions, the fluorescence intensities vary linearly with the concentration of Eu³⁺ in the range 6.0 × 10^–10–5.2 × 10^–5 mol/L, with a detection limit of 5.0 × 10^–10 mol/L. The interference from some rare earth metals and other inorganic ions are described. The method is a selective, sensitive, rapid, and simple analytical procedure for the determination of europium(III) in high-purity yttrium oxide and synthetic samples. The mechanism of fluorescence enhancement was also studied.__________From Zhurnal Analiticheskoi Khimii, Vol. 60, No. 4, 2005, pp. 372–377.Original English Text Copyright © 2005 by Tianlin Yang, Wenwu Qin, and Weisheng Liu.The article was submitted by the authors in English.     

A new procedure for the spectrophotometric determination of nitrogen(II) oxide in solutions

A new simple and reliable procedure was developed for the spectrophotometric determination of nitrogen(II) oxide. The procedure is based on the determination of excess oxygen after its reaction with NO. Alkaline solutions of thiourea dioxide were used for the determination of oxygen. It was found that the decomposition of an alkaline solution of thiourea dioxide under aerobic conditions is accompanied by the formation of dithionite, and its concentration is proportional to the concentration of oxygen in the solution. The absorbance of the resulting dithionite was measured at 315 nm. The solutions obeyed Beers law at oxygen concentrations of 1 × 10^–5–1.5 × 10^–3 M. The analytical range for NO was 1 × 10^–5–1.5 × 10^–3 M. The proposed procedure was also used for the determination of nitrogen(II) oxide in aqueous-ethanolic solutions.Translated from Zhurnal Analiticheskoi Khimii, Vol. 60, No. 1, 2005, pp. 27–29.Original Russian Text Copyright © 2005 by Pukhovskaya, Guseva, Makarov, Naidenko.     

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.     

Influence of Micelles of Different Types of Surfactant on the Mechanism of Diphenylamine Oxidation with Potassium Persulfate

Data on diphenylamine oxidation with potassium persulfate in aqueous-organic micellar solutions of different surfactants are generalized. The general effects of different surfactants are explained by the fact that different parts of micelles influence particular steps of multistep chemical reactions. This approach will enable one to control the formation rates of the intermediate or final product by making use of reaction specificity.__________Translated from Kinetika i Kataliz, Vol. 46, No. 3, 2005, pp. 390–393.Original Russian Text Copyright © 2005 by Gevorkyan.     

Spectrophotometric study of thiocyanato complexation of cobalt(II) and nickel(II) ions in micellar solutions of a nonionic surfactant triton X-100

Complexation of cobalt(II) and nickel(II) with thiocyanate ions has been studied by precise spectrophotometry in aqueous and micellar solutions of a nonionic surfactant Triton X-100 of varying concentrations (20–100 mmol-dm^–3). With regard to cobalt(II), the formation of [Co(NCS)]⁺, [Co(NCS)₂], and [Co(NCS)₄]^2– was established. The formation constant of [Co(NCS)₄]^2–, is increased with increasing concentration of the surfactant, suggesting that the [Co(NCS)₄]^2– complex is formed in micelles. In contrast, the formation constants of [Co(NCS)]⁺ and [Co(NCS)₂] are remained practically unchanged. On the other hand, with nickel(II), the formation of sole [Ni(NCS)]⁺ and [Ni(NCS)₂] was established in both aqueous and micellar solutions examined, their formation constants being also remained unchanged. Interestingly, no higher complex was confirmed in the nickel(II) system, unlike cobalt(II). The unusual affinity of the [Co(NCS)₄]^2– complex with micelles will be discussed from thermodynamic and structural points of view.     

Studies on ZnS Nanoparticles Prepared in Aqueous Sodium Dodecylsulphate (SDS) Micellar Medium

ZnS, a large band gap material, is useful in electro-luminescence and optoelectronic devices. We herein report a method for preparation of nanosized ZnS particles in micellar medium of anionic surfactant sodium dodecylsulphate. The optical properties of the prepared ZnS nanoparticles have been studied by absorption and fluorescence methods. Electron microscopic characterization has evidenced triangular particles, an uncommon observation in the synthesis of nanomaterials. PVC membrane containing nano ZnS dispersions has been prepared and its response as Zn²⁺ ion-selective membrane has been reported.__________From Kolloidnyi Zhurnal, Vol. 67, No. 4, 2005, pp. 494–499.Original English Text Copyright © 2005 by Debolina Mitra, Indranil Chakraborty, Satya P. Moulik.The text was submitted by the authors in English.     

The size of sodium dodecyl sulfate micelles in the presence ofn-alcohols as determined by fluorescence quenching measurements

The steady-state fluorescence quenching technique was used to investigate the effect of the presence of a series of alcohol homologues of mid-sized straight chain on the size of mixed micelles of sodium dodecyl sulfate (SDS). We used pyrene at concentration of ca. 10^–6M, where only its monomer exhibits any fluorescence, as fluorescent probe, and cetylpiridinium chloride at concentrations in the range (1–9)×10^–5 M as quencher. This technique allows one to determine the micellar aggregation number. The number of alcohol molecules per micelle was calculated from reported values for the micelle-water partition coefficient. On the assumption of spherical micelles, their hydrophobic radii was then calculated. The hypothesis that micelle size is determined by the available surface area per charged headgroup is discussed in the light of the results obtained.     

The Effect of Aggregation in Aqueous Aerosil Dispersions on Their Structure and Mechanical Properties

The dynamics of the structure disintegration in the A-175 aerosil dispersions in water and sodium dodecylbenzenesulfonate (SDBS) aqueous solutions was studied by the rotational viscometry. The aqueous dispersions of aerosil were found to be characterized by a high degree of aggregation. At the volume content of the dispersed phase = 0.063–0.082, the flow of the dispersions is described in terms of the theory of highly aggregated systems. The effect of SDBS on the flow behavior of aerosil dispersions is complex. There is a range of SDBS concentrations (C = 2.87 × 10^–6–1.44 × 10^–5 mol/l) where it has a noticeable structuring effect. Aerosil dispersions in micellar SDBS solutions (C > 3.0 × 10^–3 mol/l) demonstrated the behavior of slightly structured systems characterized by the quasi-Newtonian flow.     

Spectral properties of carbocyanine dyes in solutions of reverse AOT micelles

Spectral and luminescence studies of an anionic carbocyanine dye in solutions of reverse AOT micelles have shown that the dye in micelle pools can occur only in the form of the trans-monomer; although aggregated forms of the dye including J aggregates can be present in micellar solution, they all are localized in the organic phase, not micellar pools.Translated from Khimiya Vysokikh Energii, Vol. 39, No. 1, 2005, pp. 21–25.Original Russian Text Copyright © 2005 by Brichkin, Kurandina, Nikolaeva, Razumov.     

Extraction-Coulometric Determination of Copper as Copper(II) 8-Hydroxyquinolinate

Conditions were selected for the coulometric determination of copper(II) by titrating copper(II) 8-hydroxyquinolinate extracted to chloroform with electrochemically generated bromine. The procedure was tested on model solutions and samples of surface waters. The detection limit is 5 × 10^–7 M at a generation current and time of 1 × 10^–3 A and 10 s, respectively.__________Translated from Zhurnal Analiticheskoi Khimii, Vol. 60, No. 5, 2005, pp. 504–506.Original Russian Text Copyright © 2005 by Shlyamina, Morozova, Anisimova, Budnikov.     

Solubility, Acid–Base and Complexation Properties of Calix[4]resorcinarene in Aqueous Solutions of Nonionic Surfactants

Solubility and acid–base properties of calix[4]resorcinarene (H₈L) in aqueous solutions of nonionic surfactants Triton X-100, Triton X-405, and Brij-35, as well as isopropanol were studied by pH-potentiometry. The dependence of the amount of a nonionic surfactant necessary to dissolve H₈L on the length of ethylene oxide chain was found. The dissociation constants of macrocycle for the first four steps are low sensitive to the medium nature (micellar or water–alcohol solutions). Complexation ability of the [H_{8 – n} L] ^n– anions with respect to tetramethyl- and tetraethylammonium, N-methylpyridinium, and [Co(En)₂(C₂O₄)]⁺ cations was studied by pH-potentiometry. A noticeable increase in the selectivity of guest–host binding was found on going from aqueous or water–alcohol to micellar solutions.     

Formation of rodlike micelles of dimethyloleylamine oxide in aqueous solutions: effects of addition of HCl and NaCl on the micelle size and the intermicellar interaction

Angular dependence of light scattering has been measured for aqueous solutions of dimethyloleylamine oxide in the presence of HCl and NaCl. In micellar solutions more concentrated than 0.1×10^–2 g cm^–3, rodlike micelles are dominantly formed, and their properties are strongly reflected in the characteristics of the solutions. The aggregation number, radius of gyration and even flexibility of the rodlike micelles increase with the addition of HCl as well as NaCl. The increase of HCl concentration up to 10^–3 N makes the aggregation number of rodlike micelles as large as 58,000, when 0.01 M NaCl is present. The large micelle size would be stabilized by the dehydration of the amine oxide group and the hydrogen bonding between nonprotonated and protonated molecules in a micelle.In aqueous solutions without HCl and NaCl or in their presence at very low concentrations, the light scattering is subject to the effects of both external and internal interferences. The effect of external interference can be separated from the effect of internal interference by applying the Zernike-Prins equation to the observed angular dependence of light scattering. Then the second virial coefficient and the pair interaction potential of rodlike micelles can be derived by means of certain approximate methods. The addition of HCl to 10^–3 N makes both repulsive and attractive forces stronger and the resulting potential well deeper, but the addition of NaCl depresses such an effect of HCl considerably.