Mise en évidence d'un nouvel acide tungstique en solution. Filiations avec d'autres polytungstates

1977 ◽  
Vol 55 (21) ◽  
pp. 3758-3762 ◽  
Author(s):  
Jean Lemerle ◽  
Jean Lefebvre
Keyword(s):  
Solid State ◽  
Ion Exchange ◽  
Aqueous Solutions ◽  
Room Temperature ◽  
Tungstic Acid ◽  
Pure Acid ◽  
X Ray ◽  
Reduced Forms

A new tungstic acid has been prepared in aqueous solutions by ion exchange. At room temperature gelation occurs in solutions in a few hours, and 3 or 4 days after, the yellow oxide WO3 precipitates. In aqueous solutions, this acid is formed by tetramers of W6O192− units, which give a gel after association. X-ray analyses of tungstic acid in the solid state demonstrate the absence of crystallinity. In hydroorganic medium, tungstic acid is stabilized in solution, but exists in equilibrium with the Y tungstic and hexatungstic (Fuchs) anions. The condensation of the Y acid and one of its reduced forms is discussed. The pure acid forms of hexatungstic (Fuchs) and Y ions are obtained in solutions and in the solid state.

Effectiveness of Calcium Deficiency in Nanosized Hydroxyapatite for Removal of Fe(II), Cu(II), Ni(II) and Cr(VI) Ions from Aqueous Solutions

2019 ◽  
Vol 56 ◽  
pp. 17-27
Author(s):  
Van Dat Doan ◽  
Van Thuan Le ◽  
Hoang Sinh Le ◽  
Dinh Hien Ta ◽  
Hoai Thuong Nguyen
Keyword(s):  
Electron Microscopy ◽  
Ion Exchange ◽  
Aqueous Solutions ◽  
Calcium Deficiency ◽  
Exchange Mechanism ◽  
Precipitation Method ◽  
X Ray ◽  
Transmission Electron ◽  
Bet Method ◽  
Langmuir Isotherm Model

In this work, nanosized calcium deficient hydroxyapatite (nCDHA) was synthesized by the precipitation method, and then utilized as an adsorbent for removal of Fe (II), Cu (II), Ni (II) and Cr (VI) ions from aqueous solutions after characterizing it by various techniques as scanning electron microscopy (SEM), transmission electron microscopy (TEM), Fourier-transform infrared spectroscopy (FTIR), X-ray diffraction (XRD), energy-dispersive X-ray spectroscopy (EDX) and BET method. A possible structure of synthesized nCDHA was proposed. The adsorption study indicated that the adsorption equilibrium is well fitted with Langmuir isotherm model with the maximum adsorption capacities followed the order of Fe (II) > Cu (II) > Ni (II) > Cr (VI) with the values of 137.23, 128.02, 83.19 and 2.92 mg/g, respectively. The ion-exchange mechanism was dominant for the adsorption of metal ions onto nCDHA at initial metal concentrations lower than 0.01 mol/L. Along with the ion-exchange mechanism, there was an additional precipitation occurred on the surface of nCDHA in the case of Fe (II) and Cu (II) at initial concentrations higher than 0.01 mol/L.

Structural characterization of two K2SnX(PO4)3 (X=Fe,Yb) with langbeinite structure

2006 ◽  
Vol 21 (3) ◽  
pp. 214-219 ◽  
Author(s):  
Abderrahim Aatiq ◽  
Btissame Haggouch ◽  
Rachid Bakri ◽  
Youssef Lakhdar ◽  
Ismael Saadoune
Keyword(s):  
Solid State ◽  
Powder Diffraction ◽  
Room Temperature ◽  
Cell Parameter ◽  
Rietveld Analysis ◽  
Conventional Solid State Reaction ◽  
X Ray ◽  
Octahedral Sites ◽  
Parameter Values

Structures of two K2SnX(PO4)3(X=Fe,Yb) phosphates, obtained by conventional solid state reaction techniques at 950 °C, were determined at room temperature by X-ray powder diffraction using Rietveld analysis. The two materials exhibit the langbeinite-type structure (P213 space group, Z=4). Cubic unit cell parameter values are: a=9.9217(4) Å and a=10.1583(4) Å for K2SnFe(PO4)3 and K2SnYb(PO4)3, respectively. Structural refinements show that the two crystallographically independent octahedral sites (of symmetry 3) have a mixed Sn∕X (X=Fe,Yb) population although ordering is stronger in the Yb phase than in the Fe phase.

Spektralreines Bis(phthalocyaninato)protactinium(IV) / Spectroscopically Pure Bis(phthalocyaninato)protactinium(IV)

1980 ◽  
Vol 35 (5) ◽  
pp. 564-567 ◽  
Author(s):  
Franz Lux ◽  
Oskar F. Beck ◽  
Heinz Krauß ◽  
David Brown ◽  
Tze C. Tso
Keyword(s):  
Solid State ◽  
Temperature Profile ◽  
Powder Diffraction ◽  
Phthalic Acid ◽  
Room Temperature ◽  
X Ray ◽  
Derivative Spectroscopy ◽  
Solid State Spectrum

Abstract Spectroscopically pure PaPc2 has been prepared by reaction between PaI4 · 4 CH3CN and o-phthalic acid dinitrile in 1-chloronaphthalene followed by sublimation at 5 · 10-3 Pa in a temperature profile with three clearly defined zones (520 °C/350 °C/room temperature). This procedure gives a product almost completely free of H2Pc impurity which is known to have been present in previously reported complexes of the type AnPc2. Thus, the trace of H2Pc in the substance could only be detected by derivative spectroscopy. X-ray powder diffraction shows the compound to be isostructural with ThPc2 and UPc2. The ligand spectrum is typical of AnPc2 complexes, f-f Bands observed in a solid state spectrum provide additional proof that the compound is PaIV Pc2.

Synthesis of Li0.6Zn1.2PO4 and its Selectivity to Li+ Exchange

2012 ◽  
Vol 442 ◽  
pp. 54-57
Author(s):  
Heng Li
Keyword(s):  
Solid State ◽  
Ion Exchange ◽  
Chemical Analysis ◽  
Surface Adsorption ◽  
Insertion Reaction ◽  
Spinel Type ◽  
X Ray ◽  
Crystallization Method ◽  
Treated Sample ◽  
Saturation Capacity

The ion-exchanger Li0.6Zn1.2PO4of spinel type was prepared by a solid state reaction crystallization method. The extraction/insertion reaction with this material was investigated by X-ray, saturation capacity of exchange, and Kd measurement. The experimental results have proved that the acid-treated sample has a capacity of exchange 2.4mmol•g-1for Li+in the solution, The chemical analysis showed that the Li+extraction/insertion progressed mainly by ion-exchange mechanism and surface adsorption.

scholarly journals Structure and electric properties of cerium substituted SrBi1.8Ce0.2Nb2O9 and SrBi1.8Ce0.2Ta2O9 ceramics

2016 ◽  
Vol 10 (3) ◽  
pp. 183-188 ◽  
Author(s):  
Mohamed Afqir ◽  
Amina Tachafine ◽  
Didier Fasquelle ◽  
Mohamed Elaatmani ◽  
Jean-Claude Carru ◽  
...  
Keyword(s):  
Dielectric Constant ◽  
Solid State ◽  
Room Temperature ◽  
Single Phase ◽  
Solid State Reaction Method ◽  
X Ray Diffraction ◽  
Reaction Method ◽  
X Ray ◽  
Lcr Meter ◽  
Curie Temperature Tc

SrBi1.8Ce0.2Nb2O9 (SBCN) and SrBi1.8Ce0.2Ta2O9 (SBCT) powders were prepared via solid-state reaction method. X-ray diffraction analysis reveals that the SBCN and SBCT powders have the single phase orthorhom-bic Aurivillius structure at room temperature. The contribution of Raman scattering and FTIR spectroscopy of these samples were relatively smooth and resemble each other. The calcined powders were uniaxially pressed and sintered at 1250?C for 8 h to obtaine dense ceramics. Dielectric constant, loss tangent and AC conductivity of the sintered Ce-doped SrBi2Nb2O9 and SrBi2Ta2O9 ceramics were measured by LCR meter. The Ce-doped SBN (SBCN) ceramics have a higher Curie temperature (TC) and dielectric constant at TC (380?C and ?? ~3510) compared to the Ce-doped SBT (SBCT) ceramics (330?C and ?? ~115) when measured at 100Hz. However, the Ce-doped SBT (SBCT) ceramics have lower conductivity and dielectric loss.

Crystallochemistry and structural studies of two newly CaSb0.50Fe1.50(PO4)3 and Ca0.50SbFe(PO4)3 Nasicon phases

2006 ◽  
Vol 21 (1) ◽  
pp. 45-51 ◽  
Author(s):  
Abderrahim Aatiq ◽  
My Rachid Tigha ◽  
Rabia Hassine ◽  
Ismael Saadoune
Keyword(s):  
Solid State ◽  
Room Temperature ◽  
Rietveld Analysis ◽  
Structural Studies ◽  
Hexagonal Cell ◽  
Conventional Solid State Reaction ◽  
Space Group ◽  
X Ray ◽  
Cell Parameters ◽  
Crystallographic Structures

Crystallographic structures of two new orthophosphates Ca0.50SbFe(PO4)3 and CaSb0.50Fe1.50(PO4)3 obtained by conventional solid state reaction techniques at 900 °C, were determined at room temperature from X-ray powder diffraction using Rietveld analysis. The two compounds belong to the Nasicon structural family. The space group is R3 for Ca0.50SbFe(PO4)3 and R3c for CaSb0.50Fe1.50(PO4)3. Hexagonal cell parameters for Ca0.50SbFe(PO4)3 and CaSb0.50Fe1.50(PO4)3 are: a=8.257(1) Å, c=22.276(2) Å, and a=8.514(1) Å, c=21.871(2) Å, respectively. Ca2+ and vacancies in {[Ca0.50]3a[◻0.50]3b}M1SbFe(PO4)3 are ordered within the two positions, 3a and 3b, of M1 sites. Structure refinements show also a quasi-ordered distribution of Sb5+ and Fe3+ ions within the Nasicon framework. Thus, in {[Ca0.50]3a[◻0.50]3b}M1SbFe(PO4)3, each Ca(3a)O6 octahedron shares two faces with two Fe3+O6 octahedra and each vacancy (◻(3b)O6) site is located between two Sb5+O6 octahedra. In [Ca]M1Sb0.50Fe1.50(PO4)3 compound (R3c space group), all M1 sites are occupied by Ca2+ and the Sb5+ and Fe3+ ions are randomly distributed within the Nasicon framework.

Structural Study of an Acyclic Diterpene From Eremophila Species

1996 ◽  
Vol 49 (6) ◽  
pp. 701 ◽  
Author(s):  
YM Syah ◽  
EL Ghisalberti ◽  
BW Skelton ◽  
AH White
Keyword(s):  
Solid State ◽  
Single Crystal ◽  
Structural Study ◽  
Room Temperature ◽  
State Structure ◽  
Solid State Structure ◽  
X Ray

The solid-state structure of the semicarbazone derivative (3) of the aldehyde diacid (1), an acyclic diterpene isolated from Eremophila species, has been determined by a single-crystal room-temperature X-ray study. Crystals of (3) are triclinic, Pī , a 14.642(7), b 14.371(6), c 12.823(6) Ǻ, α 76.59(4), β 66.09(4), γ 72.97(4)°, Z = 4; R was 0.052 for 2265 independent 'observed' (I > 3σ(I)) diffractometer reflections.

Synthesis and conformational studies of 9-benzyloxy-18-substituted [3.3]metacyclophanes

2015 ◽  
Vol 93 (11) ◽  
pp. 1161-1168 ◽  
Author(s):  
M. Monarul Islam ◽  
Tomiyasu Hirotsugu ◽  
Taisuke Matsumoto ◽  
Junji Tanaka ◽  
Takehiko Yamato
Keyword(s):  
Solid State ◽  
Intramolecular Cyclization ◽  
Acid Treatment ◽  
Room Temperature ◽  
Coupling Reaction ◽  
Chair Conformation ◽  
Cyclization Reaction ◽  
Conformational Studies ◽  
X Ray ◽  
H Nmr

A series of syn-[3.3]metacyclophanes (MCPs) containing internal substituted benzyloxy group have been synthesized by the modified TosMIC coupling reaction followed by acid treatment and Wolff–Kishner reduction. anti-Mono- and di-benzyloxy[3.3]MCPs are synthesized by O-benzylation of the corresponding hydroxy[3.3]MCPs, which are obtained by demethylation of methoxy[3.3]MCPs with BBr3 at room temperature. An interesting and intriguing result was obtained when syn-6,15-di-tert-butyl-9-methoxy-18-methyl[3.3]MCP-2,11-dione was treated with TMSI to afford the formation of a dihydrobenzofuran ring by a nucleophilic intramolecular cyclization reaction. The 1H NMR and X-ray analysis of 6a confirms that it adopts a syn (chair–chair) conformation in both solution and solid state.

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