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- Author or Editor: M. Crespi x
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Abstract
Metal complexes of calcium with 5,7-dibromo, 7-iodo and 5-chloro-7-iodo-8-hydroxyquinolate were precipitated in aqueous ammonia and acetone medium, except for the solid state compound with 5,7-dichloro-8-hydroxyquinoline which hasn"t been obtained under these conditions. The complexes obtained through the mentioned precipitation are Ca[(C9H4ONBr2)2]3H2O, Ca[(C9H5ONI)2]2H2O and Ca[(C9H4ONICl)2]2.5H2O. Their intermediate from the thermal decomposition found through TG/DTA curves in air indicated the presence of different kinds of calcium carbonates related to the reversibility and crystalline structure, depending on the original compounds. The initial compounds and the intermediate from the thermal decomposition were also characterized through IR spectra and X-ray diffraction.
Abstract
Fluoride glasses have been extensively studied due to their high transparency in the infrared wavelength. The crystallization kinetics of these systems has been studied using DTA and DSC techniques. Most of the experimental data is frequently investigated in terms of the Johnson-Mehl-Avrami (JMA) model in order to obtain kinetic parameters. In this work, DSC technique has been used to study the crystallization of fluorozirconate glass under non-isothermal conditions. It was found that JMA model was not fit to be applied directly to these systems, therefore, the method proposed by Mlek has been applied and the Šestk-Berggren (SB) model seems to be adequate to describe the crystallization process.
Abstract
PHB [poly (3-hydroxybutyrate)], post-consumer soft-drink bottles poly (ethylene terephthalate) PET (herein named PET-R) and PHBPET-R (blends of PHB and PET-R in several compositions) samples were evaluated by differential scanning calorimetry (DSC) and scanning electronic microscopy (SEM) in order to verify their thermal properties and porosity according to amounts of PET-R added the blends. The DSC curve showed that the solvents used to solve the polymer mixture cause changes in the thermal behavior of PET-R films and in PHBPET-R blends. SEM studies of the PHBPET-R blends show that with a gradual mass increase of PET-R, there are gradual increases in the porosity of the films.
Abstract
We studied the preparation of some specific adsorbers capable of isolating and concentrating actinides. Bases of the 8-hydroxyquinoline family, diphosphineamine and tribenzylamine, salted by benzohydroxamic, benzylic or phthalic acid, are able to complex actinides in different oxidation states. As a result of the presence of the benzene rings, all the compounds are easily incorporated into active charcoal to obtain adsorbers with a highly specific surface. The adsorption behaviors of uranyl U(VI) ion, thorium(IV) and Eu(III) were studied by evaluating their distribution coefficients, K d. Results show that all the prepared salts can adsorb the ions in the III and IV oxidation state from weak acid solutions, whereas uranyl ion is adsorbed mainly from weak basic solutions. The prepared compounds can be used successfully to absorb and concentrate actinides from nearly neutral solutions, such as natural waters. The 8-hydroxyquinoline salt of the benzylic anion showed the highest adsorption values and thus seems to be the most appropriate salt to use in the analysis of actinides in water.
Characterisation of lead rhodizonate as barium and radium adsorber from fresh water
I. Preparation and characterisation of lead rhodizonate
Abstract
A new adsorber for concentrating barium and radium from diluted solutions and from fresh waters was prepared. It consists of basic lead rhodizhonate, namely [Pb(OH)]2C6O6·PbC6O6·H2O, supported on activated charcoal. It was named LEHRO. Preparation conditions, solubility and barium, or radium, adsorption from solutions of different pH were investigated.
Abstract
Magnesium ion was reacted with 5,7-dibromo-, 5,7-dichloro-, 7-iodo-and 5-chloro-7-iodo-8-hydroxyquinoline, in acetone/ammonium hydroxide medium under constant stirring to obtain (I) Mg[(C9H4ONBr2)2]2H2O; (II) Mg[(C9H4ONCl2)2]3H2O; (III) Mg[(C9H5ONI)2]2H2O and (IV)Mg[(C9H4ONICl)2]2.5H2O complexes. The compounds were characterized by elemental analysis, IR spectra, ICP, TG-DTA and DSC. Through thermal decomposition residues were obtained and characterized, by X-ray diffractometry, as a mixture of hexagonal MgBr2 and cubic MgO to the (I) compound at 850C; cubic MgO to the (II), (III) and (IV) compounds at750, 800 and 700C, respectively.
Abstract
In this present work, barium ion was reacted with different ligands which are 5,7-dibromo 5,7-dichloro, 7-iodo and 5-chloro-7-iodo-8-hydroxyquinoline, in acetone/ammonium hydroxide medium under constant stirring and the obtained compounds were as follows: (I) Ba[(C9 H4 ONBr2 )2 ]⋅1.5H2 O; (II) Ba[(C9 H4 ONCl2 )(OH)]⋅1H2 O; (III) Ba[(C9 H5 ONI)2 ]⋅1H2 O and (IV) Ba[(C9 H4 ONICl)2 ]⋅5H2 O, respectively. The compounds were characterized by elemental analysis, infrared absorption spectrum (IR), inductively coupled plasma spectrometry (ICP), simultaneous thermogravimetry-differential thermal analysis (TG-DTA) and differential scanning calorimeter (DSC). The final residue of the thermal decomposition was characterized as orthorhombic BaBr2from (I); the intermediate residue, as a mixture of orthorhombic BaCO3 and BaCl2 and cubic BaO and the final residue, as a mixture of cubic and tetragonal BaO and orthorhombic BaCl2 (II); the intermediate residue, as orthorhombic BaCO3 and as a final residue, a mixture of cubic and tetragonal BaO from (III); and the intermediate residue, as a mixture of orthorhombic BaCO3 and BaCl2 and as a final residue, a mixture of cubic and tetragonal BaO and orthorhombic BaCl2 from (IV).
Abstract
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.
