The self-hardening activity of fly ashes was investigated looking for the possibility of their chemical reactions with water without additives. A method had to be developed for separation of the structural water from the adsorbed or free one. The decomposition of the chemically bound water was measured by thermogravimetry. The‘I’ dimensionless number proved to be applicable for the quantitative characterisation of the measured data with more DTG peaks. The examined reaction depends on the chemical composition and the physical structure of the fly ashes and the time of interaction with water. The SO3 content seems important, but the characteristics of the formed compounds differ deeply from the CaSO4·2H2O. The observed and examined reaction is an important factor of the self-hardening process of fly ash deposits.
The phase diagram for the AgNO3−KNO3 system has been determined using differential scanning calorimetry (DSC). Eutectic point has been found at 391 K andXAg=0.580 mole fraction AgNO3. The DSC curves indicate the existence of an intermermediate compound (AgNO3·KNO3) in the KNO3-rich region of the phase diagram. This compound was identified in the solid phase by X-ray diffraction. The melting and the
crystallization processes were followed with the aid of a hot stage microscope, too.
Authors:F. Paulik, S. Gál, and K. Mészáros Szécsényi
A method is described for the microdistillation of liquids using quasi-isothermal quasi-isobaric thermogravimetry. The liquidus
curve determined under quasi-equilibrium conditions gives useful information about the composition and some thermal properties
of the sample. The method could be attractive for the mineral oil, lacquer, biological and organochemical industry.
Authors:K. Szécsényi, M. Arnold, K. Tomor, and F. Gaál
The thermal behavior of different fly ashes from the electrical precipitators of various pulverized carbon fuel-fired boilers
was investigated by means of simultaneous TG, DTG, DTA and EGA analysis. The carbon and sulfur contents of the samples were
determined by gastitrimetry. The compositions of the samples were examined by X-ray diffraction. The quantitative oxide analysis
of the ashes was carried out by means of a classical method.
Authors:K. Mészáros Szécsényi, T. Wadsten, A. Kovács, and G. Liptay
Manganese(II) chloride complexes with 3,4- and 3,5-lutidine have been prepared. The crystal symmetry and cell dimensions have
been calculated on the basis of powder diffraction data. The compounds were characterised also by FT-IR spectrometry. The
thermal decomposition of the complexes has been studied by thermogravimetry and DSC. By plotting densities vs. molar mass,
the diagram obtained has correspondence to similar observations in other solid metal-lutidine complex systems.
Authors:V. Leovac, E. Ivegeš, K. Szécsényi, K. Tomor, G. Pokol, and S. Gal
Solvate complexes of UO22+ andN(1), N(4)-bis(salicylidene)-S-methylisothiosemicarbazone, (H2Me-L1), of general formula [UO2(Me-L1)S] (S= H2O, MeOH, EtOH, Py, DMF and DMSO) were synthesized. The methanolic UO22+” adducts of N(1)-benzoylisopropylidene-N(4)-salicylidene-S-alkylisothiosemicarbazone, (H2R-L2,R=Me, Prn) of general formula [UO2(R-L2)· MeOH], were also prepared. Thermal decomposition of the complexes was investigated in air and argon. The complexes decompose
to α-U3O8 in air, while in argon the decomposition is not completed up to 1000 K. The temperature and the mechanism of decomposition
of the complexes are a function of the solvent belonging to the inner coordination sphere.
Authors:Z. Leka, V. Leovac, S. Lukić, T. Sabo, S. Trifunović, and K. Szécsényi
(NH4)3L, a new dithiocarbamato
derivative of iminodiacetate, has been synthesized. The coordination properties
of the ligand were tested in reactions with copper(II), nickel(II) and palladium(II)
salts in acidic solutions. Complexes with a general formula M(H2L)2
were obtained, with the coordination taking place through the sulfur atoms
of the dithiocarbamate moiety. The new compounds were characterized by elemental
analysis, UV/VIS and IR spectroscopy, thermal analysis and magnetic measurements.
In addition, the ligand was characterized by 1H-
and 13C-NMR spectroscopy and molar conductivity
measurements. The copper(II) complex is paramagnetic, while the nickel(II)
and palladium(II) compounds are diamagnetic. The thermal decomposition of
all compounds is continuous and the thermal stability of the complexes is
higher than that of the ligand, as expected.
Authors:K. Mészáros Szécsényi, T. Wadsten, B. Carson, É. Bencze, and G. Liptay
Compounds obtained by a solid–gas phase reactions between copper(II) chloride and bromide and 2,4-, 2,6- 3,4- and 3,5-lutidines
were studied using thermogravimetry, far-infrared, electronic spectroscopy and X-ray diffraction. The results were compared
with the corresponding data for the similar compounds with methylpyridines and 2,4,6-collidine. A special attention was paid
to the host-guest phenomenon, a new structural feature of transition-metal halide complexes.
Authors:K. Mészáros Szécsényi, V. Leovac, Ž. Jaćimović, V. Češljević, A. Kovács, G. Pokol, and S. Gál
We report the synthesis and the characterization (elemental analysis, FT-IR spectroscopy, thermal methods and molar conductivity
measurements) of the mixed complexes of zinc with acetate and 3-amino-5-methylpyrazole, HL1, [Zn(OAc)2(HL1)2], or 3-amino-5-phenylpyrazole, HL2 [Zn(OAc)2(HL2)2], or 4-acetyl-3-amino-5-methylpyrazole, HL3, [Zn(OAc)(L3)(HL3)]2, with isothiocyanate and HL2 [Zn(SCN)2(HL2)2], or HL3 [Zn(SCN)2(HL3)2], and with nitrate, isothiocyanate and 3,5-dimethyl-1-carboxamidinepyrazole, HL4 [Zn(NO3)(NCS)(HL4)2].
The thermal decomposition of the complexes is generally continuous resulting zinc oxide as end product,except [Zn(OAc)(L3)(HL3)]2 in which case a well-defined intermediate was observed between 570–620 K. On the basis of the IR spectra and elemental analysis
data of the intermediate a decomposition scheme is proposed.