Kinetics of ytterbium(III) extraction with Cyanex 272 using a constant interfacial cell with laminar flow

Studies have been made on the kinetics of ytterbium(III) with bis-(2,4,4-trimethylpentyl) phosphinic acid (Cyanex 272, HA) in n-heptane using a constant interfacial cell with laminar flow. The stiochiometry and the equilibrium constant of the extracted complex formation reaction between Yb3+ and Cyanex 272 are determined. The extraction rate is dependent of the stirring rate. This fact together with the Ea value suggests that the mass transfer process is a mixed chemical reaction-diffusion controlled at lower temperature, whereas it is entirely diffusion controlled at higher temperature. The rate equations for the ytterbium extraction with Cyanex 272 have been obtained. The rate-determining step is also made by predictions derived from interfacial reaction models, and through the approximate solutions of the flux equation, diffusion parameters and thickness of the diffusion film have been calculated.

Extraction and stripping of ytterbium (III) from H2SO4 medium by Cyanex 923

The extraction and stripping of ytterbium (III) from sulfuric acid medium using Cyanex 923 in heptane solution was investigated. The effects of extractant concentration, pH and sulfate ion as well as stripping agents, acidity and temperature on the extraction and stripping were studied. The equilibrium constants and thermodynamic parameters, such as Delta H (10.76 kJ(.)mol(-1)), Delta G (-79.26 kJ(.)mol(-1)) and Delta S (292.41 J(.)K(-1.)mol(-1)), were calculated. The extraction mechanism and the complex species extracted were determined by slope analysis and FrIR spectra. Furthermore, it was found that the extraction of Yb (III) from sulfuric acid medium by Cyanex 923 increased with pH, concentration of SO42-, HSO4-, and extractant concentration, and approximately a quantitative extraction of Yb (III) was achieved at an equilibrium pH near 3.0, and the extracted complex was YbSO4(HSO4)(.)2Cyanex923((o)).

Mass-transfer kinetics of ytterbium extraction with sec-nonylphenoxy acetic acid

The extraction kinetics of ytterbium with sec-nonylphenoxy acetic acid (CA-100) in heptane have been investigated using a constant interfacial area cell with laminar flow. The influence of stirring speed and temperature on the rate indicated that the extraction rate was controlled by the experiment conditions. The plot of interfacial area on the rate showed a linear relationship. This fact together with the low solubility in water and strong surface activity of CA-100 at heptane-water interfaces made the interface the most probable locale for the chemical reactions. The influences of extractant concentration and hydrogen ion concentration on the extraction rate were investigated, and the forward and reverse rate equations for the ytterbium extraction with CA-100 were also obtained. Based on the experimental data, the apparent forward extraction rate constant was calculated. Interfacial reaction models were proposed that agree well with the rate equations obtained from experimental data.

Synthesis and crystal structure of bis (tert-butyl-cyclopentadienyl)erbium ethoxide, (t-BuCp)(2)ErOEt

The formation of ( t-BuCp)(2)ErOEt was discussed. Its single-crystal structure was determined by X-ray diffraction. The crystal is monoclinic, P2(1)/c space group, a = 1.0191(2), b = 1.6203(5), c = 1.2118(3) nm, beta = 102. 960( 10)degrees, V = 1.9500 (nm(3)), Z = 2, D-c = 1.566 mg . m(-3), R = 0.0450, R-w = 0.1363. The complex is monomeric and solvent-free in the solid state. The erbium ion is coordinated by two tert-butyl-cyclopentadienyl rings and one oxygen atom of ethoxy group to form a seven-coordinated complex.

Extraction and separation of thorium and ytterbium with bis (2,4,4-trimethylpentyl) phosphinic acid using a hollow fiber membrane extractor

The based membrane extraction of Th4+ and Yb3+ was studied in HBTMPP-heptane using a hollow fibber membrane. The separation method of Th4+ and Yb3+ was proposed by kinetics competition. The separation operation of Th4+ and Yb3+ mixture was carried out by two successive extraction and stripping simultaneously. The concentration ratio of Th4+ to Yb3+ is 16.74 in the stripping solution. The recovery and purity of Th4+ are 71.6% and 95.74% respectively.

1.54 mu m infrared photoluminescence and electroluminescence from an erbium organic compound

Infrared emission at 1.54 mu m excited optically and electrically from an erbium organic compound tris(acetylacetonato)(1,10-phenanthroline) erbium [Er(acac)(3)(phen)] is observed. The rare-earth complex is dispersed into a polymer matrix of poly(N-vinylcarbazole) (PVK) to fabricate an electroluminescent (EL) device with an ITO/PVK:Er(acac)(3)(phen)/Al:Li/Ag structure, where ITO represents indium-tin-oxide-coated glass. The device shows infrared EL emission at 1.54 mu m, which suggests a simple and cheap method to obtain a light source for 1.54-mu m-wavelength devices in optical communications. (C) 2000 American Institute of Physics. [S0021-8979(00)00301-7].

LB multilayers and superlattice films of erbium fatty acid salts

Multilayers of Y-type bilayers of pure and mixed erbium palmitate(EP), nonadecanate(Er) and behenate(EB) on CaF2 substrates were prepared by conventional Langmuir-Blodgett (LB) method. II is demonstrated that two systems composed of alternating bilayer of different fatty acid salts are unidimensional superlattices. These LB films were characterized by means of x-ray photoelectronic Spectrometry (XPS), FTIR and x-ray diffraction (XRD) measurements.

Synthesis and crystal structure of a polymeric erbium(III)-sodium(I) coordination complex of picolinic acid N-oxide

A new Er(III)-Na(I) coordination polymer of stoichiometry [NaEr2L5(H2O)(6)(NO3)](NO3). 3.5H(2)O (HL = picolinic acid N-oxide) has been synthesized and characterized by single-crystal X-ray analysis. Crystals are triclinic, P (1) over bar with a = 9.823(2), b = 12.453(2), c = 20.643(4) Angstrom; alpha = 98.49(3), beta = 101.40(3), gamma = 108.69(3)degrees; V = 2284(1) Angstrom(3); Z = 2. Of the two independent eight-coordinate erbium(III) ions in this complex, one is surrounded by four bidentate chelating L ligands, and the other by one bidentate chelating L ligand, four aqua ligands and two anti-carboxylate oxygen atoms from two neighboring [ErL4] units. The sodium(I) ion is in a distorted octahedral environment, being coordinated by a unidentate nitrate anion, three aqua ligands and two anti-carboxylate oxygen atoms from two adjacent [ErL4] units. The complex is built from zigzag chains of syn-anti carboxylate-bridged erbium(III) moieties directed in the a direction, which are cross-linked pairwise by aqua-bridged dimeric sodium(I) units. The resulting composite polymeric chains are further connected by hydrogen bonds to form a three-dimensional network.

Quantitative structure-property relationships for colour reagents and their colour reactions with ytterbium using regression analysis and computational neural networks

In this paper, the new topological indices A(x1)-A(x3) suggested in our laboratory and molecular connectivity indices have been applied to multivariate analysis in structure-property studies. The topological indices of twenty asymmetrical phosphono bisazo derivatives of chromotropic acid have been calculated. The structure-property relationships between colour reagents and their colour reactions with ytterbium have been studied by A(x1)-A(x3) indices and molecular connectivity indices with satisfactory results. Multiple regression analysis and neural networks were employed simultaneously in this study.

STUDIES ON STRUCTURE-PROPERTY RELATIONSHIP BETWEEN COLOR REAGENTS AND SENSITIVITY OF THEIR COLOR-REACTIONS WITH YTTERBIUM BY TOPOLOGICAL INDEXES

In this paper A, topological indices and molecular connectivity inidces have been applied to multivariate analysis in structure-property studies. The topological indices of twenty asymmetrical phosphone bisazo derivatives of chromotropic acid have been calculated. The structure-property relationships between color reagents and molar absorptivity of color reactions with ytterbium have been studied by A(m) indices and molecular connectivity indices. Good results have been obtained.

STRUCTURE OF AN ERBIUM COMPLEX WITH L-PROLINE

In the structure of catena-poly[{triaqua(L-pro-line-O)erbium(III)}-bis-mu-(L-proline-O:O')-{triaqua-(L-proline-O)erbium(III)}-bis-mu-(L-proline-O:O') hexaperchlorate], each Er3+ ion is coordinated by five carboxyl O atoms from the L-proline molecules and three water molecules. Four of the SiX L-proline molecules act as bidentate bridging ligands to link the Er3+ ions through the carboxyl groups, thus producing a one-dimensional chain structure. The other two ligands coordinate unidentately to the rare-earth ions. Hydrogen bonds formed between the coordinated water molecules and between the water and unidentate proline ligand stabilize the polymeric chain.

STRUCTURE OF AN ERBIUM COORDINATION COMPOUND WITH L-PROLINE, ([ER(PRO)2(H2O)5]CL3)(N)

catena-Poly[{pentaaqua(L-proline-O)-erbium-mu-(L-proline-O:O')} trichloride], {[Er(C5H9-NO2)2(H2O)5]Cl3}n, M(r) = 594.0, monoclinic, P2(1), a = 8.294 (1), b = 10.981 (3), c = 11.934 (3) angstrom, beta = 107.04 (2)degrees, V = 1039.2 (4) angstrom3, Z = 2, D(x) = 1.90 g cm-3, lambda(Mo Kalpha) = 0.71069 angstrom, mu = 45.2 cm-1, F(000) = 586, T = 298 K, R = 0.0244 for 1711 unique reflections [I > 3 sigma(I(o))]. The crystal consists of one-dimensional chains of infinite length in which one L-proline ligand bridges two neighboring Er ions, the other L-proline ligand being monodentate.

LIFETIMES OF RYDBERG LEVELS IN THE PERTURBED 6SNP 3P2 SERIES OF YTTERBIUM-I

Using three-step laser excitation in an atomic beam and a time-resolved spectroscopy technique, we measured both the lifetimes of the Rydberg levels of Yb I belonging to the perturbed series 6nsp 3P2 and the lifetimes of the perturbing 4f(13)5d(2)6s 3P2, 1D2 levels. An expected shortening has been observed for the lifetimes of those levels which are strongly mixed with the perturbers.

STUDIES ON ORGANOLANTHANIDE COMPLEXES .40. SYNTHESIS AND X-RAY STRUCTURE OF BIS (2-METHOXYETHYLCYCLOPENTADIENYL) YTTRIUM AND YTTERBIUM TETRAHYDROBORATES

New bis (2-methoxyethylcyclopentadienyl) yttrium and ytterbium tetrahydroborates (Ln = Y, 1; Yb, 2) have been synthesized in good yield by the reaction of bis (2-methoxyethylcyclopentadienyl) lanthanide chlorides (Ln = Y, Yb) with sodium borohydride in THF at room temperature. The title complexes were characterized by elemental analyses, MS, H-1 NMR and IR spectra. The crystal structures of 1 and 2 have been determined by X-ray diffraction. 1 crystallizes from THF-n-Hexane in space group Pna2(1) with unit cell parametert: a = 1.2390(3), b = 1.1339(2), c = 1.1919 (2) nm and V = 1.6745(6) nm3 with z = 4 for D(c) = 1.39 g.cm-3.The structure was solved by direct method and refined to final R = 0.061 (for 1730 observed reflections). The Space group of 2 is Pna2(1) with unit cell parameters: a = 1.2399(6), b = 1.1371(5), c = 1.1897(2) nm and V = 1.6773(1) nm3 with z = 4 for D(c) = 1.72 g.cm-3, R = 0.038 (for 2157 observed reflections). The X ray structures and IR reveal the bidentate yttrium and ytterbium tetrahydroborate complexes with the intramolecular coordination bonds between lanthanide metal and ligand oxygen atoms.

SYNTHESIS, THERMAL-STABILITY AND X-RAY CRYSTAL-STRUCTURE OF THE BIS(CYCLOPENTADIENYL)YTTERBIUM NAPHTHOXIDE DERIVATIVE (C5H5)2YB(OC10H7)(THF)

Cp3Yb (Cp = C5H5) reacts with a-naphthol (HNP) in THF to form Cp2Yb(NP)(THF) (1), which crystallizes in the space group P2(1)/n with unit cell dimensions a = 8.084(2), b = 15.996(6), c = 15.973(7) angstrom, beta = 98.95(3), V = 2040.3 angstrom and D(calc.) = 1.69 g cm-3 for Z = 4. Least-squares refinement based on 2242 observed reflections converged to a final R value of 0.081. The average Yb-C(Cp) distance is 2.60(2) angstrom and Yb-O(THF) and Yb-O(NP) distances are 2.30(1) and 2.06(1) angstrom, respectively. The title compound loses the coordinated THF molecule readily by heating under vacuum to give dimeric [Cp2Yb(NP)]2 (2), which undergoes disproportionation to give Cp3Yb and Yb(NP)3 on heating above 230-degrees-C.