Extraction of lanthanide ions from acidic and strongly acidic media by phosphine oxide derivatives using temperature-induced phase separation

A composite for the extraction of lanthanide ions from strongly acidic media by temperature-induced phase separation was designed based on the nonionic surfactant Triton X-100 and new phosphine oxide derivatives. The dependence of the efficiency and selectivity of micellar extraction on the length of the hydrophobic substituent at the P=O group is determined by both the influence of hydrophobic substituents on the electron-donor capacity of the P=O group and the solubility of phosphine oxides in aqueous and micellar phases. The nitric acid concentration was found to influence the efficiency of extraction of lanthanide ions by phosphine oxides with different structures. An increase in the concentration of nitric acid in an aqueous medium from 0.1 to 1 mol L⁻¹ leads to a decrease in the degree of extraction by water-soluble derivatives and a substantial increase in the degree of extraction by phosphine oxides, which are soluble only in the micellar phase of Triton X-100.     

Enhanced electrochemiluminescence from Os(phen)2(dppene) (phen=1,10-phenanthroline and dppene=bis(diphenylphosphino)ethene) in the presence of Triton X-100 (polyethylene glycol tert-octylphenyl ether)

The effects of the non-ionic surfactant Triton X-100 (polyethylene glycol tert-octylphenyl ether) on the properties of Os(phen)₂(dppene)²⁺ (phen=1,10-phenanthroline and dppene=bis(diphenylphosphino)ethene) electrochemiluminescence (ECL) have been investigated. The anodic oxidation of Os(phen)₂(dppene)²⁺ produces ECL in the presence of tri-n-propylamine (TPrA) in aqueous surfactant solution. Increases in ECL efficiency (≥3-fold) and TPrA oxidation current (≥2.0-fold) have been observed in surfactant media with experiments supporting adsorption of surfactant on the electrode surface.     

Electrochemically initiated chain polymerization of pyrrole in aqueous media

The electrochemical quartz crystal microbalance has been employed to investigate the electropolymerization of pyrrole in a variety of aqueous electrolytes. In contrast to the generally accepted cation–radical coupling process for the electropolymerization of pyrrole, an electrochemically initiated chain polymerization, featuring a high polymerization rate and involving little charge transport, was found under specific conditions in the presence of ClO^?₄, BF^?₄, and PF^?₆ electrolytes. The more typical cation-radical coupling mechanism, characterized by a constant polymerization charge to mass deposited ratio, is observed in the presence of Cl^?, NO^?₃, dodecyl sulfate, copper phthalocyanine tetrasulfonate, β-cyclodextrin tetradecasulfate, and poly(styrene sulfonate). Electrochemical characterizations of polypyrrole films prepared in aqueous ClO^?₄ electrolytes reveal that the polymer formed via chain polymerization exhibits the ability to transport both cations and anions during electrochemical switching between redox states, while the polymer synthesized through cation-radical coupling is only capable of transporting a single ionic species.     

The Photostabilization of Hemoglobin in Triton X-100 Aqueous Solution and Triton X-100/n-C5H11OH/H2O Microemulsion

The influence of UV-irradiation on the interaction of hemoglobin (Hb) with Triton X-100 is investigated by UV–Vis absorption spectroscopy, fluorescence spectroscopy and freeze-fractured transmission electron microscopy. It is found that in Triton X-100/H₂O systems Hb can convert to hemichrome but heme is not present, whereas in Triton X-100/n-C₅H₁₁OH/H₂O microemulsion Hb can convert to hemichrome and then induce the heme monomer to leave the hydrophobic cavity of Hb. UV-irradiation can also convert Hb to hemichrome, and subsequently make heme to be photodegraded, in which the conversion rate depends on the structure of the surfactant aggregates. Furthermore, in order to understand the mechanism of photostabilization of Hb in Triton X-100 systems, the photostabilization of heme in the Triton X-100 aqueous solutions and Triton X-100/n-C₅H₁₁OH/H₂O microemulsions has been studied.     

Oxygen effect in the radiolysis of Triton X-100 aqueous solution

Experiments with Triton X-100 as a model surfactant were performed under steadystate conditions, using deoxygenated solutions as well as those saturated with N₂O, O₂ or N₂O/O₂ mixtures. The Triton X-100 decomposition yield was dependent on the O₂ content of the irradiated system. Oxygen promoted surfactant decomposition in aqueous solution containing only Triton X-100.     

Effect of inorganic positive ions on the adsorption of surfactant Triton X-100 at quartz/solution interface

The electrode-separated piezoelectric sensor (ESPS), an improved setup of quartz crystal microbalance (QCM), has been employed to investigate the adsorption behavior of nonionic surfactant Triton X-100 at the hydrophilic quartz-solution interface in mineralized water medium in situ, which contained CaCl2 0.01 mol·L?1, MgCl2 0.01 mol·L?1, NaCl 0.35 mol·L?1. In a large scale of surfactant concentration, the effects of Ca2 , Mg2 and Na on the adsorption isotherm and kinetics are obviously different. In aque-ous solution containing NaCl only, adsorption of Triton X-100 on quartz-solution interface is promoted, both adsorption rate and adsorption amount increase. While in mineralized water medium, multivalent positive ions Ca2 and Mg2 are firmly adsorbed on quartz-solution interface, result in the increasing of adsorption rate and adsorption amount at low concentration of surfactant and the peculiar desorption of surfactant at high concentration of Triton X-100. The results got by solution depletion method are in good agreement with which obtained by ESPS. The "bridge" and "separate" effect of inorganic positive ions on the adsorption and desorption mechanism of Triton X-100 at the quartz- solution interface is discussed with molecular dynamics simulations (MD), flame atomic absorption spectrometry (FAAS) and atomic force microscopy (AFM) methods.     

Factors Influencing Electroanalytical Measurements In Aqueous Surfactant Media

Abstract

Surfactant solutions of sodium dodecyl sulfate (SDS), cetyltrimethylammonium bromide (CTAB) and Triton X-100, have been studied for their utility as media for electroanalytical measurements. Each medium possesses a wide potential window with low background currents within which electrochemical measurements can be conducted. the potential windows at a glassy carbon electrode are +1.2 to -1.6 V for 0.1 M TEAP/SDS, 0.1 M NaCl/0.1 M SDS and 0.1 M NaCl/1.2% Triton X-100, and +0.6 to -1.6 V for 0.1 M NaCl/32 mM CTAB (V vs. Ag/AgCl (3M NaCl)). the M(II/I) redox couples of [ReCdmpe)₃]^2+/+ and [Tc(dmpe)₃]^2+/+ were used as electrochemical probes of each surfactant medium. Results are discussed In terms of the solubilization and interaction of the complexes with the micellar environment. Several factors are described which affect the general shape of the voltammograms as well as the observed values of E^o'; these include (i) the structure of the micelle as influenced by the supporting electrolyte, (ii) the electrostatic affinity of the probe complex for the micellar environment and (iii) the solubilization of each component of the redox couple in the micelle.     

Interactions between nonpolar surfaces in mixed solutions of cationic and nonionic surfactants

The interaction energy between hydrophobic SiO₂ particles in aqueous solutions of a cationic surfactant (dodecylpyridinium bromide, DDPB), a nonionic surfactant (Triton X-100, TX-100), and their mixed solutions was measured as a function of concentration. Synergism has been observed in mixed surfactant solutions: the surfactant concentration required for achieving the set interaction energy in the mixed solutions was lower than in the solutions of the individual surfactants. The molecular interaction parameters in surfactant mixtures were calculated using the Rosen model. Chain-chain interactions between nonionic and cationic surfactants were suggested as the main reason for the synergism.     

Surface Property of Nonionic Surfactant Triton X-100 in an Ionic Liquid

A common nonionic surfactant Triton X-100 was dissolved in a commercial ionic liquid (IL) 1-butyl-3-methylimidazolium tetrafluoroborate (bmimBF₄). The surface tension of the bmimBF₄ solution was decreased with increasing the content of surfactant Triton X-100, a similar phenomenon with aqueous solution systems. Dynamic surface properties of Triton X-100 in bmimBF₄ were measured. It was found that pure IL solvents need rearrangement at the air-bmimBF₄ interface during the beginning stage of absorption. Moreover, the adsorption model was found to be in accord with the diffusion-controlled adsorption mechanism, and further, the dilute bmimBF₄ solutions are close to the diffusion-controlled adsorption.     

Influence of the Structure of Nonionic Surfactants and the Length of Alkyl Substituents of Calix[4]resorcinarenes on Their Solubility, Acid–Base, and Complexation Properties

Regularities of solubilization of calix[4]resorcinarenes (H₈L) with the variable length of hydrophobic radicals (R = CH₃, C₃H₇, C₅H₁₁, C₇H₁₅, C₈H₁₇, C₉H₁₉, C₁₁H₂₃) by the micelles of nonionic surfactants Triton X-100 and Triton X-405 in aqueous solutions were studied using solubility measurements. It was found that the solubilization capacity of surfactant micelles with respect to H₈L and [H₄L]^4– depends on the extension (thickness) of their polar layers. It was shown by means of potentiometric titration that, in solutions of nonionic surfactants, the constants of the interaction between tetraanions [H₄L]^4– and tetrametylammonium ions depend on the structure and concentration of nonionic surfactants and the hydrophobicity of H₈L molecules. A change in the affinity of the [H₄L]^4– anions for protons and tetramethylammonium cations in nonionic surfactant solutions was revealed in relation to the length of substituents R and reagent concentrations.     

Formation and redox behaviour of polycarbazole prepared by electropolymerization of solid carbazole crystals immobilized on an electrode surface

Carbazole solid crystals have been mechanically attached to platinum or gold electrodes by two different methods and investigated by cyclic electrochemical quartz crystal microbalance measurements in the presence of aqueous acidic media. It was demonstrated that oxidative dimerization and polymerization can also be accomplished under such conditions. During electropolymerization, anions and water molecules enter the surface layer; however, these species leave the film after the reduction of the polymer formed. The mass changes observed in the course of the redox transformations of polycarbazole film can be explained by potential- and time-dependent sorption/desorption of H⁺ and ClO₄ ⁻ ions. The electroactivity of the polymer diminishes in more dilute acid media; however, it is recovered again in concentrated HClO₄ solutions. In more dilute acid solution the extent of the water sorption (film swelling) increases.     

AOT/Triton X-100混合反胶束体系的导电性能

采用聚乙二醇辛基苯基醚(TritonX-100)和二(2-乙基己基)琥珀酸磺酸钠(AOT)双表面活性剂,与正己烷、正己醇和水构成混合反胶束体系;研究了表面活性剂质量比、助表面活性剂含量、水油体积比和温度等因素对反胶束体系导电性能的影响,同时采用循环伏安法研究了K3Fe(CN)6/K4Fe(CN)6在该体系中的电化学行为.结果表明:由两种表面活性剂构成的反胶束体系电导率σ明显大于单一表面活性剂反胶束体系电导率;体系电导率随AOT与TritonX-100的质量比w(w=mAOT∶mTritonX-100)的变化而变化,w为0-0.4时,电导率随w增大而线性增大,之后增加趋势变缓;w=0.96时,σ达到稳定值576μS·cm-1.混合体系电导率随溶水量的增大及温度的上升而提高;而增加助表面活性剂可显著降低体系的电导率.在所研究体系中,Fe(CN)36-/Fe(CN)46-电化学反应对的氧化还原峰电位几乎不随扫描速率变化,峰电位差约为75mV,峰电流的比值约为1,氧化峰电流与扫描速率的平方根成正比,说明K3Fe(CN)6/K4Fe(CN)6在混合反胶束体系中显示出良好的氧化还原可逆性,反应由扩散步骤控制.     

Assembly properties of Triton X-100/phosphatidylcholine aggregates during liposome solubilization

The assembly properties of the nonionic surfactant Triton X-100 and phosphatidylcholine (PC) aggregates during the overall solubilization process of PC liposome were investigated. Permeability alterations were detected as a change in 5(6)-carboxyfluorescein (CF) released from the interior of vesicles and bilayer solubilization as a decrease in the static light scattered by liposome suspensions. A direct dependence was established between the bilayer/aqueous phase surfactant partition coefficients (K), the growth of vesicles and the leakage of entrapped CF in the initial interaction steps (surfactant to phospholipid molar ratioRe up to 0.2). These changes may be related to the increasing presence of surfactant molecules in the outer monolayer of vesicles. In theRe range 0.2–0.35 the coexistence of a low vesicle growth with a constant increase of CF release may be correlated with the decrease inK (increased rate of flip-flop of surfactant molecules). Furthermore, in theRe range between 0.64 and 2.0 (lytic levels) almost a linear dependence was detected between the composition of these aggregates (Re) and the decrease in both the surfactant-PC aggregate size and the static light scattered by the system. This dependence was not observed in the last solubilization steps (Re range 2.0–2.60) possibly due to the increased formation of mixed micelles in this interval. The fact that the free Triton X-100 concentration at sublytic and lytic levels showed respectively lower and similar values than its critical micelle concentration confirms that permeability alterations and solubilization were determined respectively by the action of surfactant monomer and by the formation of mixed micelles.Abbreviations PC phosphatidylcholine - PIPES piperazine-1,4 bis(2-ethanesulphonic acid) - T_X-100 Triton X-100 - CF 5(6)-carboxyflucrescein - Re enective surfactant/lipid molar ratio - Re _SAT effective surfactant/lipid molar ratio for bilayer saturation - Re _SOL enective surfactant/lipid molar ratio for bilayer solubilization - S _W surfanctant concentration in the aqueous medium - S _B surfactant concentration in the bilayers - S _T total surfactant concentration - K bilayer/aqueous phase surfactant partition coefficient - K _SAT bilayer/aqneous phase surfactant partition coefficient for bilayer saturation - K _SOL bilayer/aqueous phase surfactant partition coefficient for bilayer solubilization - PL phospholipid - TLC-FID thinlayer chromatography/flame ionization detection system - PI polydispersity index - CMC critical micellar concentration - r ² regression coefficient     

Solution properties of hydrophobically modified acrylamide-based polysulfobetaines in the presence of surfactants

Polymer–surfactant interactions in aqueous solutions of a acrylamide-based, hydrophobically modified polysulfobetaine (ADS) containing 3-[N-(2-methacryloxylethyl)-N,N-dimethylammonio]-propane sulfonate and stearyl methylacrylate, with sodium dodedyl sulfate (SDS), N-dodecyl-N,N,N-trimethylammonium bromide (DTAB), and Triton X-100 were studied using surface tension, rheology, Rayleigh light scattering, and dynamic laser light scattering techniques. The purpose of this study was to highlight the influences of the surfactant structure and the nature of the surfactant head group on the polymer–surfactant interactions. The results show that the interaction and association between ADS and surfactants are distinctly varied depending on surfactant type and surfactant concentration. SDS produced the strongest interactions with ADS, while DTAB and Triton X-100 interact with ADS to a lesser degree, which is attributed to surfactant structure and the nature of the surfactant head group. For SDS and DTAB, there are two driving forces for the complexation of the polymer and surfactants, resulting from the electrostatic interaction and the hydrophobic association. However, for the nonionic surfactant Triton X-100, only hydrophobic association predominated in the interaction between ADS and the surfactant. The mechanism and reconstruction of the polymer–surfactant complexes have been evaluated and discussed.     

Titania nanocomposite films derived by modified sol-gel process for photovoltaic application

Titania nanocomposite films were fabricated by spin-coating from sol-gel derived pastes of TiO₂ powder in titanium isopropoxide sol. The thin films were characterized for structural, optical and hydrophilic properties and evaluated as electrodes in a photoelectrochemical cell. Addition of TiO₂ powder increased film thickness, reduced transmittance, water contact angle and electrochemical impedance, and promoted photocurrent generation. Increasing Triton X-100 surfactant loading in the composite slurry influenced film texture and transmittance, and the resultant films exhibited a lower photocurrent yield but were more hydrophilic to favor charge transfer at the electrode/electrolyte interface. The aggregation of TiO₂ particles of different sizes in the composite film facilitates light-scattering and electron transport to enhance quantum efficiency. The addition of Triton X-100 surfactant influences the distribution of scattering centers to increase transparency.     

Ion and solvent transfer discrimination at a nickel hydroxide film exposed to LiOH by combined electrochemical quartz crystal microbalance (EQCM) and probe beam deflection (PBD) techniques

A combined electrochemical quartz crystal microbalance (EQCM) and probe beam deflection (PBD) instrument was used to monitor the mobile species transfers associated with the redox processes of thin (Γ100–150 nmol cm⁻²) α- and β-nickel hydroxide films exposed to aqueous LiOH solution. A comparison of the measured PBD signal with the predicted PBD profiles, calculated by temporal convolution analysis of the current and mass responses, enabled the contributions to redox switching of anion (OH⁻) and solvent (H₂O) transfers to be discriminated quantitatively. The responses from the combined instrument are reconciled in terms of H⁺ deintercalation/intercalation within the nickel hydroxide structure as OH⁻ ions enter/exit the film. Hydroxide ion movement is associated with a counterflux of water. Thin nickel hydroxide films show a gradual α→β phase transformation with continuous voltammetric cycling, especially when the films are exposed to high concentrations of electrolyte. α-Films are characterised by OH⁻ transfers that dominate the H⁺ and H₂O movements; β-films are characterised by an increased participation of water and protons to the exchange dynamics.     

An EQCM investigation of charging RuO2 thin films prepared by the polymeric precursor method

An electrochemical quartz crystal microbalance (EQCM) study of RuO₂ thin films, prepared by the sol-gel precursor method, is presented. The X-ray diffraction (XRD) analysis demonstrates that RuO₂ films were crystallized in the rutile phase and scanning electron microscopy investigations indicated the formation of a smooth surface. Cyclic voltammetry and EQCM studies were performed simultaneously in order to investigate the charging processes of the RuO₂ films in 0.1 M HClO₄. The voltammetric and mass versus potential responses present three well-defined regions associated with the RuO₂ redox couples. Based on these results and on the mass-charge relationships, the corresponding charging mechanisms are proposed. In the potential region governed by the Ru³⁺/Ru⁴⁺ redox couple, the mass-charge relation can be associated with the double-injection of protons and electrons. The other regions correspond to water release and oxyhydroxide species formation during charging.     

Monitoring formation of poly(neutral red) film by EQCM

An electrochemical quartz crystal microbalance (EQCM) is employed for monitoring the growth of poly(neutral red) films on platinum in the electrolytic solution containing 5.0 mmol dm⁻³ neutral red, 0.3 mol dm⁻³ H₂SO₄, and 0.5 mol dm⁻³ Na₂SO₄. The in situ measurement of the frequency changes of the EQCM reveals that both the adsorption/desorption of neutral red and the formation of poly(neutral red) film can be observed together with anion sorption/desorption during the redox transformation of the polymer, and that the polymerization rate of neutral red increases slowly before the 11th cycle and then increases quickly with increasing number of potential cycles. Published in Russian in Elektrokhimiya, 2007, Vol. 43, No. 3, pp. 284–289. The text was submitted by the authors in English.     

Enzymatic Resolution of Ethyl α-Hydroxyphosphinates in a Modified Reaction Environment

The enzymatic resolutions of two racemic ethyl hydroxyalkane(P-phenyl)phosphinates were performed by both esterification and hydrolysis approaches. The first reaction was performed in anhydrous diisopropyl ether with triethylamine or pyridine as additives by using lipases from three different sources (Candida cylindracea, Aspergillus niger, and Mucor javanicus). The increase in enantioselectivity was observed when NEt₃ was applied. The second reaction—lipase-catalysed hydrolysis of ethyl butyryloxyalkane(P-phenyl)phosphinates—was carried out by Candida cylindracea lipase in diisopropyl ether saturated with water or in aqueous solutions containing MgCl₂, LiCl, or Triton X-100. The usefulness of biphasic systems consisting of diisopropyl ether and water or aqueous solution of MgCl₂, LiCl, or Triton X-100 also were tested. The use of biphasic system in the presence of Triton X-100 resulted in the higher conversion of the substrates.     

Mixed micellization of gemini surfactant with nonionic surfactant in aqueous media: a fluorometric study

Herein we report on the study of the interactions between alkanediyl-α,ω-type cationic dimeric (gemini) surfactant and the nonionic Triton X-100 in aqueous medium. The critical micelle concentrations of binary mixtures were determined by fluorometric study. Using the regular solution theory for the analysis of the experimental data, the attractive nature of interactions and synergistic behavior of gemini surfactant and Triton X-100 mixture were demonstrated. The micelle aggregation number was measured using steady state fluorescence quenching method. The micropolarity, binding constant and dielectric constant of mixed systems were determined from the ratio of peak’s intensity (I ₁/I ₃) in the pyrene fluorescence emission spectrum.