Search results for "mole fraction"
showing 10 items of 62 documents
Using 1-Ethyl-3-methylimidazolium Trifluoromethanesulfonate as an Entrainer for the Extractive Distillation of Ethanol + Water Mixtures
2009
Isobaric vapor−liquid equilibria (VLE) for the ethanol + water + [emim][triflate] ternary system have been obtained at 100 kPa using a recirculating still. The ethanol + water binary system was also obtained. Furthermore, data were simulated with the Mock’s electrolyte nonrandom two-liquid (NRTL) model, using the solvent−solvent interaction parameters obtained from VLE data of the ethanol + water system and taking the solvent−ionic liquid (IL) interaction parameters for the other binary systems from previous works. The agreement between experimental and calculated data is very good, showing the predictive capacity of the model. The addition of [emim][triflate] produces the disappearance of …
Coupled Semiconductor Systems for Photocatalysis. Preparation and Characterization of Polycrystalline Mixed WO3/WS2 Powders
1999
Mixed WO3/WS2 powders were prepared by oxidation of WS2. The physical properties of the samples were characterized by X-ray diffraction, diffuse reflectance spectroscopy, and scanning electron microscopy; they were strongly dependent upon the time and temperature of oxidation. The chemical state and the elemental distribution of the sample surface were investigated by X-ray photoelectron spectroscopy. The photocatalytic results have showed that the aqueous suspensions of the mixed WO3/WS2 systems have significantly higher activities than pure WS2 and WO3 for the photodegradation of phenol. The enhanced performance can be related to the presence of heterojunctions WO3/WS2 on the single parti…
Vapor–liquid equilibrium of binary mixtures of trichloroethylene with 1-pentanol, 2-methyl-1-butanol and 3-methyl-1-butanol at 100 kPa
1999
Abstract Isobaric vapor–liquid equilibria (VLE) have been obtained for the systems trichloroethylene+1-pentanol, trichloroethylene+2-methyl-1-butanol and trichloroethylene+3-methyl-1-butanol at 100 kPa using a dynamic still. The experimental error in temperature is ±0.1 K, in pressure ±0.1 kPa, and in the liquid and vapor mole fraction ±0.001. The three systems satisfy the point-to-point thermodynamic consistency test. All the systems show positive deviations from ideality. The data have been correlated with the Margules, van Laar, Wilson, NRTL and UNIQUAC equations.
Spin crossover in iron(II) tris(2-(2′-pyridyl)benzimidazole) complex monitored by variable temperature methods: synchrotron powder diffraction, DSC, …
2003
Abstract The thermal expansion of the spin crossover system [Fe(pybzim) 3 ](ClO 4 ) 2 · H 2 O (pybzim=2-(2 ′ -pyridyl)benzimidazole) has been determined from powder X-ray data between 50 and 250 K; the wavelength of the synchrotron source was 1.21888(1) A. The unit cell parameters of the triclinic crystal system were a =12.091 A, b =12.225 A, c =14.083 A, α =77.70°, β =80.35°, γ =74.35°, and V =1944.9 A 3 at 250 K. In addition to the linear thermal expansion of the unit cell volume, an extra expansion due to the low-spin (LS) to high-spin (HS) transition is observed. The V ( T ) function shows a sudden increase comparable with the step in the effective magnetic moment at the transition reg…
Kinetics of Complex Formation between DNA and Cationically Charged Cylindrical Brush Polymers Observed by Stopped Flow Light Scattering
2009
The complex formation of pUC19 DNA and a cylindrical brush polymer with quaternized poly(vinyl pyridinium) side chains is investigated by stopped flow light scattering (LS). In highly dilute solutions up to two kinetic processes are observable, depending on the mole fraction of anionic charges, x(anion) . For x(anion) 0.4-0.5 only one kinetic process was identified leading to the largest complexes at x(anion) = 0.4 well below charge stoichiometry. For 0.2 < x(anion) < 0.4 two kinetic growth processes were identified: The initially formed complexes on the time scale of a few hundred milliseconds keep growing by an unusual fractal growth process until after several minutes they become stab…
Structural phase transitions coupled with prominent dielectric anomalies and dielectric relaxation in [(CH3)3NH]2[KCo(CN)6] and mixed [(CH3)3NH]2[KFe…
2020
The crystals of pure [(CH3)3NH]2[KFe(CN)6] (TrMAFe) and [(CH3)3NH]2[KCo(CN)6] (TrMACo) as well as their mixed crystals (TrMAFexCo1−x), with different ratios of x = 0, 0.12, 0.18, 0.49, 0.56, 0.73, 0.81, 1.0, have been grown from aqueous solutions. The structure of TrMACo has been determined at 360 K to be cubic (Fmm). In phase II (100 K), the TrMACo crystal is monoclinic (C2/c). The thermal stability of the pure and mixed crystals has been determined by using both DTA and TGA. Based on the DSC results, we have found a single phase transition (PT) for both pure and mixed crystals. The Fe(III) concentration was estimated by using the SEM technique. We have found a linear relationship between …
Square wave voltammetric determination of the redox state of a reversibly oxidized/reduced depolarizer in solution and in solid state
2012
Abstract Square wave voltammetric measurements allows for determining the composition of system containing a reversibly reducible/oxidable electroactive species in two oxidation states. The method is based on recording the ratio of reverse to forward peak currents. That ratio can be correlated with the molar fraction of the oxidized (or reduced) form of the depolarizer. The method was compared with cyclic voltammetric methods suggested in literature and it was tested using Fe ( CN ) 6 3 - / Fe ( CN ) 6 4 - in solution phase. Application to solid state systems is illustrated by the dehydroindigo/indigo couple in synthetic Maya Blue-type specimens prepared from indigo plus different clays whe…
Variable-temperature X-ray crystal structure determinations of {Fe[tren(6-Mepy)3]}(ClO4)2and {Zn[tren(6-Mepy)3]}(ClO4)2compounds: correlation of the …
2007
Variable-temperature X-ray crystal structure determinations (80–330 K) on compounds {Fe[tren(6-Mepy)3]}(ClO4)2(1-Fe) {tren(6-Mepy)3is tris[3-aza-4-(6-methyl-2-pyridyl)but-3-enyl]amine} and {Zn[tren(6-Mepy)3]}(ClO4)2(1-Zn) {tren(6-Mepy)3is tris[3-aza-4-(6-methyl-2-pyridyl)but-3-enyl]amine} were carried out together with a detailed analysis of the unit-cell volume and parameters in the spin transition region for (1-Fe). Both compounds crystallize in the monoclinic system and retained the space groupP21/cat all measured temperatures. The Fe and Zn atoms are surrounded by six N atoms belonging to imine groups and pyridine groups of the trifurcated ligand, adopting a pseudo-octahedral symmetry. …
Rate-retarding effects of mixed anionic/non-ionic micelles on the alkaline hydrolysis of the chloropentamminocobalt(III) complex
2006
Abstract Rate data for the alkaline hydrolysis of the chloropentaamminecobalt(III) cation in the presence of mixed micelles composed of (i) anionic sodium decylsulphate (SDeS) and non-ionic dodecylpenta(oxyethylene glycol) monoether (C 12 E 5 ) surfactants and (ii) anionic sodium perfluorooctanoate (SPFO) and non-ionic C 12 E 5 surfactants has been obtained at T 298 K and constant electrolyte concentration 0.08 mol dm −3 ([NaOH] = 0.01 mol dm −3 , [NaClO 4 ] = 0.07 mol dm −3 ) over a wide range of total surfactant concentration ( C t ) and anionic mole fraction ( χ ). The critical micelle concentrations (c.m.c.s) of the mixed micelles have been determined over the entire χ range by means of…
Optical method for predicting the composition of self-assembled monolayers of mixed thiols on surfaces coated with silver nanoparticles.
2012
With a simple optical method, based on UV-vis absorption spectra on glass slides, it is possible to predict the composition of self-assembled monolayers of mixed thiols, grafted on monolayers of silver nanoparticles. Glass slides are modified with the layer-by-layer technique, first forming a monolayer of mercaptopropyltrimethoxysilane, then grafting a monolayer of silver nanoparticles on it. These surfaces are further coated by single or mixed thiol monolayers, by dipping the slides in toluene solutions of the chosen thiols. Exchange constants are calculated for the competitive deposition between the colorless 1-dodecanethiol or PEG5000 thiol and BDP-SH, with the latter being a thiol-beari…