Search results for " solution"
showing 10 items of 3084 documents
Cu-Exchanged CHA-Type Zeolite from Organic Template-Free Synthesis: An Effective Catalyst for NH3-SCR
2020
A Cu-containing CHA-type zeolite was prepared via aqueous ion exchange of the CHA zeolite from organic template-free synthesis. The thus-obtained template-free Cu-CHA showed the best catalytic perf...
Energetics of Water−Dodecyl Surfactant−Macrocyclic Compound Ternary Systems
1996
Enthalpies of dilution and osmotic coefficients of sodium dodecyl sulfate (NaDS) and dodecyltrimethylammonium bromide (DTAB) in water + 18-crown-6 ether (CR) and water + β-cyclodextrin (CD) at a fixed cosolvent concentration were measured at 298 and 310 K, respectively, as functions of the surfactant concentration (mS). Enthalpies of transfer ΔH (W → W + S) of CR (0.03 m) from water to NaDS and DTAB aqueous solutions as functions of mS were also determined at 298 K. From the enthalpies of dilution the apparent (LΦ,S) and partial (L2,S) molar relative enthalpies of both surfactants were calculated. Despite CR forms inclusion complexes with the anionic surfactant only, the L2,S vs mS profiles…
Solution properties of polyelectrolytes—V. Viscometric study of mixed polyanions in pure water
1990
Abstract A viscometric study of sodium polystyrene sulphonate (NaPSS) and sodium poly( l -glutamate) (NaPLG) in salt-free water has been carried out as a function of the total concentration, cm, and the concentration of one polyelectrolyte at fixed concentration of the other. The influences of the molecular weight and concentration are considered in order to establish the degree of compatibility. For the first time, an equation is proposed to define the reduced viscosity of the NaPSS + NaPLG mixture in water. The viscometric interaction parameter, Bm, taking into account the electrostatic and thermodynamic interactions between both polyions, is defined as a geometrical mean of the contribut…
The titanium–iron–antimony ternary system and the crystal and electronic structure of the interstitial compound Ti5FeSb2
2003
Abstract Phase equilibria were established in the Ti–Fe–Sb ternary system below the TiSb2–FeSb section at 1070 K; the Sb–TiSb2–FeSb region was studied at 870 K. Investigation of the phase relations was based on X-ray diffraction experiments on arc-melted bulk alloys, which were annealed up to 350 h. Four ternary compounds were observed: TiFe1−xSb (0.64≤x≤0.70; defect TiNiSi-type), Ti1.18Fe0.57Sb (partially and statistically filled Ni2In-type), Ti1+xFeSb (−0.20≤x≤0.27; transformation from defect AlLiSi-type to the defect MnCu2Al-type), and new Ti5FexSb3−x (0.45≤x≤1.00; W5Si3-type). An extended solid solution up to about 10 at.% antimony was observed for the Laves phase Ti(Fe1−xSbx)2−y. Ti3Sb…
Predictability of properties of ternary systems solvent/solvent/polymer from interaction parameters of the binary systems—III. Analysis of binary pot…
1990
Abstract The assumption that the ternary parameter, g τ , and its derivative with respect to polymer concentration, ( ∂g τ / ∂φ 3 ) μ 1 , φ 3 → 0 , can be described by three binary interaction parameters, g o i 3 ( i = 1, 2) and g 12 , implies that these must be independent functions. This feature has been demonstrated by using g o i 3 values obtained from A/B/polymer(P) and C/D/P ternary polymer systems to predict the ternary properties, namely preferential solvation (λ), second virial coefficient ( A 2 ) and intrinsic viscosity ([η]), of a A/C/P ternary system. Two distinct polymers, polystyrene(PS) and poly(dimethylsiloxane)(PDMS), have been utilized in three solvent mixtures, benzene(BZ…
Islands of Immiscibility for Solutions of Compatible Polymers in a Common Solvent: Experiment and Theory
2009
Experimentally obtained islands of immiscibility are reported for the systems PS/PVME/THF at 20 °C and for PS/PVME/CH at 55 °C (PS: polystyrene, PVME: poly(vinyl methyl ether), THF: tetrahydrofuran, CH: cyclohexane). THF is a good solvent and CH is a marginal solvent for both polymers. In the case of THF, information on the Flory−Huggins interaction parameters of the three binary subsystems suffices for a qualitative prediction of the phase behavior of the ternary system. Quantitative agreement can be achieved by means of composition-independent ternary interaction parameters. For the marginal solvent CH, the exclusive use of binary interaction parameters wrongly predicts complete miscibili…
Evaluation of thermodynamic parameters for blends of polyethersulfone and poly(methyl methacrylate) or polystyrene in dimethylformamide
1998
Liquid-liquid phase separation phenomena have been investigated for a ternary system containing two polymers and a solvent. Namely, dimethylformamide (DMF)/polyethersulfone (PES)/poly(methyl methacrylate) (PMMA) and DMF/PES/Polystyrene (PS). The composition of the three components in the two phases in equilibrium has been determined by size exclusion chromatographic (s.e.c.) analysis. The lattice-based mean-field theory, first developed by Flory and Huggins, has been modified to adequately describe these systems. In this respect, we have assumed that the parameters depend on the polymer concentration, and we have included a ternary parameter. The phase equilibrium compositions have been use…
Thermodynamics of pseudo-ternary systems as a tool to predict the morphologies of cellulose acetate/polystyrene blends cast from tetrahydrofuran solu…
2003
Abstract The demixing behavior of the ternary system THF/CA/PS (tetrahydrofuran/cellulose acetate/polystyrene) was investigated at 25 °C. Cloud point measurements show that the system exhibits a large miscibility gap caused by the incompatibility of CA and PS. Both ends of the experimentally determined tie lines are located inside the two-phase area of the phase diagram. By means of the measured critical composition of the ternary system and the Flory–Huggins interaction parameters published for two of the binary subsystems ( χ CA/THF =0.442 and χ PS/THF =0.475) the polymer/polymer interaction parameter was adjusted (directly minimizing the Gibbs energy) to χ CA/PS =0.057. These thermodynam…
Capillary electrophoretic and nuclear magnetic resonance studies of interactions between halophenols and ionic liquid or tetraalkylammonium cations.
2003
Aqueous capillary electrophoretic studies were performed to investigate interactions between halophenols and 1-ethyl-3-methylimidazolium tetrafluoroborate or tetraethylammonium tetrafluoroborate electrolytes. In both cases, increased halogen size correlated with increased affinity for the electrolyte cation. For isomers, the ortho substituted isomer exhibited higher affinity than the para isomer. Irreproducible CE results for analyte pairs in the presence of the ionic liquid stimulated investigations of the interactions between halophenols as well as with the cations of the electrolyte. These interactions were explored by proton and fluorine one-dimensional NMR. The NMR results indicated di…
Synthesis and Characterization of Iron-Doped ZrSiO4 Solid Solutions from Gels
2011
The mechanism of formation and the structural features of tetragonal Fe–ZrO2-amorphous silica composites and particulated Fe-doped ZrSiO4 solid solutions were studied. A series of specimens with compositions Fex–ZrSiO4, 0 ≤ x ≤ 0.10 were prepared by sol–gel techniques and thermally annealed over the range of temperature between 400°C and 1600°C. Results confirmed the formation of tetragonal Fe–ZrO2 solid solution as first crystalline phase on the whole process leading to Fe-doped ZrSiO4 solid solution. The annealing temperature for the preparation of Fe-containing ZrSiO4 solid solutions was dependent on the nominal amount of iron. The Fex–ZrSiO4 solid solutions, with 0.02 < x < 0.08, were a…