Studia Universitatis Babeș-Bolyai Chemia

Permanent URI for this collectionhttp://dspace:4000/handle/123456789/2

ISSN (print): 1224-7154; ISSN (online): 2065-9520; ISSN-L: 1224-7154

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Author: search.filters.author.Thomas DIPPONG

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    INFLUENCE OF THE Ni/Mg RATIO ON THE COLOUR OF SPINEL PIGMENTS PREPARED BY A MODIFIED SOL – GEL METHOD
    (STUDIA UBB CHEMIA. Published by Babeş-Bolyai University, 2017-03-30) Firuța GOGA; Roxana DUDRIC; Liliana BIZO; Alexandra AVRAM; Alexandru-Horațiu MARINCAȘ; Csaba VARHELY Jr.; Thomas DIPPONG
    This paper focuses on the synthesis and analysis of some spinel-structured, ceramic pigment nanopowders (Mg(1-x)NiₓAl₂O₄) using a modified sol – gel method. This study emphasizes the influence of the Ni/Mg ratio and that of the thermal treatment on the properties of the obtained powders. The behavior of the dried gels during calcination was studied by differential thermal analysis. The formation of the spinel structure after calcination was analyzed using x-ray diffraction. The colour of the powders was characterized by UV – VIS spectroscopy, determining the absorption spectra. In addition, the trichromatic coordinates were determined, and the corresponding pigment positions were fixed on the chromaticity diagram.
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    SEASONAL EVOLUTION AND DEPTH VARIABILITY OF HEAVY METAL CONCENTRATIONS IN THE WATER OF FIRIZA-STRÎMTORI LAKE, NW OF ROMANIA
    (STUDIA UBB CHEMIA. Published by Babeş-Bolyai University, 2017-03-30) Thomas DIPPONG; Cristina MIHALI; Firuța GOGA; Elena CICAL
    The paper follows the spatial variability and seasonal evolution of the heavy metal content of the Firiza-Strîmtori Reservoir that is the main source of drinking water for Baia Mare city located in the northwestern part of Romania. Water samples were collected from 10 sampling points located along the median line of the lake at different depths (at surface, at 5 m, 10 m, 15 m and 20 m). The experiments were carried out in the winter, spring, summer and autumn of 2015. We determined the concentration – depth profiles, both for the heavy metals iron (Fe), manganese (Mn), zinc (Zn), copper (Cu), cadmium (Cd), lead (Pb) and also for sodium (Na), potassium (K), calcium (Ca) and magnesium (Mg). We determined the concentrations of heavy metals by atomic absorption spectrometry. We found that concentrations of heavy metals increase with depth. Generally, the concentrations of heavy metals are within the legal limits for the water used as drinking water sources. Mathematical models with high correlation coefficients were obtained in the case of heavy metal concentrations depending on depth and also for the seasonality of heavy metals upload.
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