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:K. Mészáros Szécsényi, V. Leovac, A. Kovács, G. Pokol, and Ž. Jaćimović
thermal decomposition of Cu2L2Cl4,
is described. The influence of the central ion to ligand mole ratio on the
course of complex formation is examined in reaction of L
with copper(II) chloride. In Cu(II):L mole ratio of 1:1, in methanolic solution
the reaction yields to yellow-green Cu2L2Cl4
crystals. In the filtrate a thermodynamically more stable orange Cu2L2Cl2
copper(I) complex is forming. With a Cu(II):L
mole ratio of 1:2 only the latter compound is obtained. The composition and
the structure of the compounds have been determined on the basis of customary
methods. On the basis of FTIR spectrum of the intermediate which is forming
during the thermal decomposition of Cu2L2Cl2
a decomposition mechanism is proposed.
Authors:K. Mészáros-Szécsényi, J. Päiväsaari, M. Putkonen, L. Niinistö, and G. Pokol
The coupling of a quadrupole mass spectrometer (QMS) via a heated capillary to a commercial thermogravimetric analyser is described. The amu and temperature ranges available were up to 1000 amu and 1500°C, respectively. The system was evaluated with test compounds, yielding gaseous species in the m/z range of 17-80, and then used for the study of thermal behaviour of scandium dipivaloyl methanate or Sc(thd)3 which is discussed in detail. Sc(thd)2 appears as the major Sc-containing species with m/z=411 in the gas phase at 200-300°C.
Authors:K. Mészáros-Szécsényi, E. Ivegeš, V. Leovac, A. Kovács, G. Pokol, and Ž. Jaćimović
Complexes represented by the general formula [MCl2L2] (M(II)=Zn, Mn, Co) and complexes of [Cu3Cl6L4] and CuSO4L24H2O, CoSO4L23H2O, [ZnSO4L3] where L stands for 3-amino-5-methylpyrazole were prepared. The complexes were characterized by elemental analysis, FT-IR
spectroscopy, thermal (TG, DTG, DSC and EGA) methods and molar conductivity measurements. Except for the Zn-complexes, the
magnetic susceptibilities were also determined.
Thermal decomposition of the sulphato complexes of copper(II) and cobalt(II) and the chloro complexes of cobalt(II) and manganese(II)
resulted in well-defined intermediates. On the basis of the IR spectra and elemental analysis data of the intermediates a
decomposition scheme is proposed.