Europium(III) was extracted by bis(2-ethylhexyl)phosphoric acid (HDEHP) and 8-hydroxyquinoline (HQ) in dodecane from aqueous perchlorate media of constant ionic strength (0.1M; H+, NaClO4). Slope analysis of the data indicate that three molecules of HDEHP or HQ are attached to Eu3+. Extraction constants were obtained at different temperatures. The data were used to calculate the thermodynamic parameters (G, H and S) for the extraction process in the two systems. When using mixtures of crown ethers with HDEHP no synergism was observed.
Proton-ligand stability constants for some iodo and nitro derivatives of 8-hydroxyquinoline were determined by Calvin Bjerrum potantiometric method. The stability constants of the corresponding chelates with UO2 (II), Th(IV) and Co(III) were studied potentiometrically at 25 °C by applying Irving-Rossotti computing method. The complexes of the nitro-substituted ligands were less stable than the corresponding complexes of the unsubstituted ligands. The stability constants of metal-ligands depend on the ionic radii and ionic charge of metals and also they decrease with steric repulsions of the nitro groups.
Radiometric titrations are reported based on the formation of poorly soluble chelate complexes of 8-hydroxyquinoline and its
derivatives with calcium ions. Calcium chloride reagent solution labelled with45Ca was used for the titrations. The slightly alkaline medium used in the titrations made complete the solution of the substances
and the formation of chelate complexes. The appropriate conditions of the titrations of the various compounds have been determined.
The radiometric titrations were carried out in an apparatus suitable for the detection of soft β-emitting isotopes.
The complexes formed by photosubstitution of pyrazine (Pz) in octacyanomolybdate(IV) and -tungstate(IV) with 8-hydroxyquinoline have been assigned the formulae [Mo(CN)2(OH)2(Pz)2(OX)] and [W(CN)2(OH)2(Pz)2(OX)·1.5H2O]. Coordination of Pz as an unidentate ligand by donating a lone pair of electron from nitrogen is shown by an absorption peak between 8–11 µ. Mechanism for the thermal decomposition of the complexes has been given. The formation of tungsten metal as residue in case of II has been confirmed by XRD analysis. The kinetic and thermodynamic parameters like activation energy (Ea), pre-exponential factor (A) and entropy of activation (
S#) were calculated employing different integral methods of Doyle, Coats and Redfern and Arrhenius.
H for each stage of decomposition was obtained from DSC.
The extraction behavior of octahedral and tetrahedral cobalt(II) complexes from aqueous nitrate medium was studied in the
system 8-hydroxyquinoline (HOX) and dibenzo-18-crown-6 (Db 18C6) or dibenzylamine (DBA) in chloroform at different temperatures
to evaluate the thermodynamic functions as well as the equilibrium constants of each reaction. The stoichiometry of the extracted
organic phase species were established to be Co(OX)2·Db18C6 for the octahedral cobalt and Co(OX)2·DBA for the tetrahedral cobalt.
Neutron Activation Analysis is a sensitive technique for the determination of more than seventy elements at the trace concentrations.
The NAA analysis of biological and environmental matrices suffers from interferences caused by the presence of high concentrations
of activated salts in these matrices. The high gamma-ray activities of these activated salts mask the low gamma-ray activities
of short half-lived isotopes (e.g.,66Cu,56Mn,28Al and52V) necessitating the rapid separation of trace metals from high concentrations of salts. Poly-5-vinyl-8-hydroxyquinoline has
been used to develop a new method to rapidly and quantitatively precipitate aluminum, copper, vanadium and manganese from
neutron-activated biological and environmental matrices.
Crystalline PbTiO3 was obtained through the thermal decomposition of 8-hydroxyquinolinate of lead(II) and that of titanium(IV), which was monitored
by TG/DTG/DTA under different atmospheric conditions and with varying heating rates. The compound was prepared from adding
8-hydroxyquinoline solution in the solution of metallic ions Pb(II):Ti(IV) (1:1) under constant stirring at 3C, having the
pH adjusted to 10. The results of these investigations show that different thermal behavior related to the precursor occurred
and also the consequent formation of residues which have different crystallinities. No carbonate residues from the thermal
decomposition could be determined by XRD and IR. Only PbTiO3 was observed and confirmed by DSC at 470C, temperature lower than the tetragonal-cubic transition.
Extraction of U/VI/ by mixtures of 8-hydroxy quinoline /Oxine/ and neutral donors was studied from 0.1M NaCl at a pH 4.5. The presence of a neutral donor enhanced the extraction of U/VI/ and the species responsible for synergism was established to be 11 adduct UO2Ox2S. From the data, the equilibrium constants for the adduct formation reaction were calculated and was found to be the lowest with TBP and the highest with TOPO.
A new method has been developed for the separation and determination of low-level activity of strontium-90 through its daughter product yttrium-90 from natural water. Yttrium was separated and isolated from 1001 water at pH 5.5–5.7 by 8-quinolinol substituted silica gel. The yttrium was eluted with hydrochloric acid and precipitated with ammonium oxalate. The precipitate of yttrium oxalate was counted with a low-background beta-counter. The recovery of yttrium-90 is (64±4)% (n=5).