Browsing by Author "Gentscheva G."

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    Characterization of olive meals
    (2020-01-01) Mladenov M.; Pashev A.; Gentscheva G.
    The current communication describes results of olive meals characterization. The chemical composition in respect to nutrients (N, P, K, Ca, Mg, C), some microelements and heavy metals (Al, Co, Cu, Fe, Zn, Ni, Cd, Mn, Mo, Pb, Cr, As, Se, and Sr) is studied. FAAS, ISP-MS and ATR-FTIR spectroscopy methods are used. Parameters as moisture and contents of volatile compounds, raw oil, raw fibres, raw proteins, ash residues and insoluble ash are also examined. Adequate conclusions and recommendations in respect to olive meals utilization are advanced on the ground of the results obtained.
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    Eco-Friendly Dye Removal: Black Cumin Seed Press Cake for Toluidine Blue Adsorption
    (2025-10-01) Gentscheva G.; Vassileva P.; Tzvetkova C.; Pashev A.; Yotkovska I.; Mladenov M.; Vassilev T.
    This research investigates the potential of Seed Press Cake of Nigella sativa (SPCN) as a low-cost, eco-friendly biosorbent for the removal of the cationic dye Toluidine Blue (TB) from aqueous solutions. The physicochemical properties of the material were characterized using Fourier-transform infrared (FTIR) spectroscopy, nitrogen adsorption–desorption isotherms, and scanning electron microscopy (SEM). Adsorption performance was evaluated under varying conditions, with the process best described by the pseudo-second-order kinetic model and the Langmuir isotherm, indicating monolayer adsorption. The maximum adsorption capacity was determined to be 305 mg·g−1 at 20 °C. Thermodynamic analysis revealed that the adsorption is spontaneous, exothermic, and entropy-driven. FTIR analysis indicated that TB interacts with SPCN primarily via physical interactions, including electrostatic attraction, van der Waals forces, and hydrogen bonding, without strong chemical bonding. These findings demonstrate the high potential of black cumin seed waste as a sustainable and efficient biosorbent for dye removal in wastewater treatment.
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    Study on the physicochemical and chemical parameters of drinking and surface waters from mine area at village bov, balkan mountain, Bulgaria
    (2018-01-01) Mladenov M.; Karadjova I.; Gentscheva G.; Predoeva A.
    Water quality is influenced by natural local climate, geology and anthropogenic effects. In the present study, surface waters in hydrographic area, situated in mining region, in the vicinity of abandon copper mine, are characterized and their quality assessed from the view point of the requirements of European Water Frame Directive and Drinking Water Directive. Three sampling campaigns starting at 2012 from 16 sampling sites, in different seasons were performed in order to evaluate both natural, seasonal variations connected with water regimes and anthropogenic pressures. Chemical elements (Al, As, Ba, Cd, Cr, Co, Cu, Fe, Hg, Mn, Ni, Pb, Se, U, V, Zn and lanthanides) and physicochemical parameters (pH, conductivity, hardness, chemical oxygen demand (CODKMnO4); biological oxygen demand (BOD5); dissolved oxygen; dissolved solids; suspended matter; dry residue; chlorides; sulphates; nitrates; phosphates) were measured for characterization and evaluation of different water sources in the region. Conclusions for the further use of waters from this region as tap waters were presented and validated through the determination of much more chemical elements than these required from national legislation.