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Abstract  

Copper forms of synthetic zeolite ZSM5 containing ethylenediamine (en) were characterised by methods of thermal analyses - TG, DTA and DTG in the temperature range 20-1000C, in air and in argon atmosphere. Mass spectroscopy was used for the study of the released gas products of thermal decomposition. The results of thermal analyses of three Cu(en)xZSM5 zeolitic products with different composition (x depends on the mode of preparation) checked their different thermal properties. The main part of the decomposition process occurs at considerably higher temperatures than the boiling point of ethylenediamine of all three products, it proves strong bond and irreversibility of en-zeolite interaction. According to the results of the mass spectroscopy method the decomposition process in inert atmosphere is characterised by the development of a large spectrum of products with atomic mass from 28 to 178 atomic mass units, and there is a correlation between the mode of sample preparation and the spectrum of the released products.

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Abstract  

Three interesting new compounds formed as a result of phenols-iodine redox reactions were investigated by mass spectral fragmentation (MS) and thermal analyses (TA) as well as some other physicochemical methods as microanalysis and infra-red spectroscopy to elucidate their structures. The characterization of the compounds was satisfactorily achieved by using the above analytical tools and their proposed general formulae, were found to be C24H15O8I (PC-IO 3 ), C24H14O12 I2 (PG-IO 3 ) and C12H8O6I2 (PG-IO 4 ).The fragmentation pathways of PC-IO 3 , PG-IO 3 and PG-IO 4 have been examined using electron ionization (EI) mass spectrometry in comparison with thermal analyses (TG and DTA). Both decomposition modes were investigated, and the fragmentation pathways were suggested. The combined application of mass spectrometry and thermogravimetry (MS and TG) in the analysis of the products allowed the characterization of the fragmentation pathway in MS.The major pathway in both techniques of PC-IO 3 is due to the loss of CHO followed by CH3I+2H2O. It is due to the loss of 2H2O followed by the loss of 2CH3I for PG-IO 3 . While for PG-IO 3 it is related to the loss of 2H2O followed by loss of 2CH3I molecule stepwise. Different stabilities for initial products and some fragments are discussed.

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Journal of Radioanalytical and Nuclear Chemistry
Authors: M. Olguin, M. Solache-Rios, D. Acosta, P. Bosch, and S. Bulbulian

Abstract  

The capacity of bentonite and purified bentonite to remove UO 2 2+ ions from aqueous solutions has been investigated. The UO 2 2+ uptake in these clays was determined for 0.2 and 0.002M uranyl nitrate solutions. It was found that under these conditions (0.2M) the maximum UO 2 2+ uptake was 1.010±0.070 meq UO 2 2+ /g of bentonite and 0.787±0.020 meq UO 2 2+ /g of purified bentonite. In purified bentonite UO 2 2+ sorption is irreversible up to 50 hours as no desorption was observed. Such is not the case in the natural bentonite. X-ray diffraction, thermal analyses, and transmission electron microscopy were used to characterize the solids. The uranium content was determined by neutron activation analysis.

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Abstract  

Two tris(oxouranium)-substituted Keggin and Dawson sandwich-type tungstophosphate heteropolyanions Na12[(UO)3(H2O)6(PW9O34)2]·21 H2O (1) and Na18[(UO)3(H2O)6(P2W15O56)2]·27 H2O (2) have been prepared by reaction of uranium sulphate with [PW9O34]9− and [P2W15O56]12−, respectively, in aqueous media at 4.7 pH. The products were characterized by elemental and thermal analyses, IR, UV-Vis spectroscopy and magnetical susceptibility. The results of these studies suggest that the compounds obtained from Keggin and Dawson trilacunary anions are 2∶3 sandwich-type complexes and both exhibit a square antiprismatic stereochemistry for uranium(IV) with retention of polyoxometallate parent structure.

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Abstract  

In this paper, novel results on the blue thermally stimulated luminescence (TSL) emission of ulexite (NaCaB5O6(OH)65H2O) have been studied. The four maxima appearing at 60, 110, 200 and 240C on the TSL glow curves of this borate could be respectively associated to: (i) the first dehydration (NaCaB5O6(OH)65H2O→NaCaB5O6(OH)63H2O), (ii) the creation-annihilation of the three-hydrated phase, (iii) the Na-coordinated chains dehydroxylation and the starting point of the alkali self-diffusion through the lattice and (iv) the amorphisation of the lattice. These results are fairly well correlated with the differential thermal analyses (DTA), in situ thermal observations under environmental scanning electron microscope (TESEM) and thermal X-ray diffraction (TXRD) techniques.

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Abstract  

The aim of this paper is to define the characteristics of crystalline phase ETS-10 obtained from gel with dodecyltrimethylammonium bromide, as an organic template. ETS-10 zeolites has been synthesised under hydrothermal conditions from gels of composition 5Na2O–3KF–TiO2–6.4HCl– xC12TMAB –7.45SiO2–197.5H2O (where x=0.0, 0.25, 0.55, 1.0 and 1.5) with dodecyltrimethylammonium bromide. The crystalline phases synthesised with organic salt have an exothermal peak at ca. 360°C, due to the degradation of organic entrapped in the porous structure. Physical-chemical properties of C12TMAB -ETS-10 are studied by XRD, SEM and thermal analyses.

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Abstract  

Mn(II), Co(II), Ni(II) and Cu(II) chelates with3-phenyl-4-(p-methoxyphenylazo)-5-pyrazolone have been synthesized and were characterized by elemental and thermal analyses as well as by IR, UV-VIS, 1HNMR, conductometric and magnetic measurements. The first stage in the thermal decomposition process of these complexes shows the presence of water of hydration, the second denotes the removal of the coordinated water molecules. The final decomposition products were found to be the respective metal oxides. The data of the investigated complexes suggest octahedral geometry with respect to Co(II) 1:1, tetrahedral for Ni(II) 1:1and 2:3; square planar for Cu(II) 1:1 and 2:3; the complexes with no coordinated water molecules (2:3) Co(II) and Mn(II) complexes are tetrahedral.

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Abstract

New complexes of type [Cu(L1)2(OH2)]·4H2O (1), [Cu(L2)(OH2)]·0.5H2O (2) and [Cu3(L3)2(OH2)3]·0.5H2O (3) were synthesized by [1 + 1], [1 + 2] and [1 + 3], respectively, template condensation of 2,4,6-triamino-1,3,5-triazine and salicylic aldehyde in the presence of copper(II). The features of complexes have been established from microanalytical, IR and UV–Vis data. The thermal analyses have evidenced the thermal intervals of stability and also the accompanying thermodynamic effects. Processes as water elimination and oxidative degradation of the organic ligands were observed. After water elimination, complexes revealed a similar thermal behaviour. The final product of decomposition was copper(II) oxide as powder X-ray diffraction indicated.

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Abstract  

New complexes:Zn(Hsalox)(ox), Zn(Hsalox)(NHPh), Zn(Hsalox)(Hsal) and Zn(Hsalox)2(1,2-diMeim) have been synthesised as a result of a reaction of Zn(salox) and Zn(Hsalox)2 (where: salox 2–=OC6H4CHNO2–, Hsalox =OC6H4CHNOH) with 8-hydroxyquinoline (Hox), o-aminophenol (NH2Ph), o-hydroxybenzoic acid (H2Sal) and 1,2-dimethylimidazole (1,2-diMeim). Chemical, X-ray and thermal analyses of the complexes and their sinters have been carried out. Thermal decomposition pathways have been postulated for the complexes. The mixtures about not definite composition have been obtained as a result of a reaction of zinc(o-hydroxybenzaldoximates) with imidazole(Him) and 4-methylimidazole (4-MeHim).

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Abstract  

M2UO2(C2O4)2nH2O compounds (M=K, Rb and Cs)have been prepared and characterized by chemical and thermal analyses as well as by X-ray diffraction and infrared spectroscopy. X-ray powder data show that the compounds belong to an orthorhombic system. Thermal and infrared studies show that the compounds decompose to M2UO4 through the formation of alkali metal carbonate and UO2 as intermediates. K2UO2(C2O4)2⋅3H2O, and Rb2UO2(C2O4)2⋅2H2O gave K2UO4, Rb2UO4 at 700 and 600C respectively, while in the case of Cs2UO2(C2O4)2⋅2H2O, the intermediate products of decomposition reacted to yield Cs2U4O13 at 1000C.

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