Stefov, Viktor
Preferred name
Stefov, Viktor
Official Name
Stefov, Viktor
Main Affiliation
Email
viktorst@pmf.ukim.mk
8 results
Now showing 1 - 8 of 8
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Item type:Publication, Preparation, Structural, Thermogravimetric and Spectroscopic Study of Magnesium Potassium Arsenate Hexahydrate(Wiley, 2014-10-23); - Some of the metrics are blocked by yourconsent settings
Item type:Publication, Thermal, spectral and microscopic studies of water-rich hydrate of the type Mg2KH(PO4)2·15H2O. Thermal transformations(Elsevier BV, 2015-11); ; Cahil, Adnan - Some of the metrics are blocked by yourconsent settings
Item type:Publication, Мultivariate analysis for rapid screening and prediction of solid-state compatibility in pharmaceutical preformulation studies-paving the road for machine learning(Society of Chemists and Technologists of Macedonia, 2024-05-19) - Some of the metrics are blocked by yourconsent settings
Item type:Publication, Thermal analysis of multi-walled carbon nanotubes material obtained by catalytic pyrolysis of polyethylene(Society of Chemists and Technologists of Macedonia, 2015-11-12); ; Bogoeva-Gaceva, Gordana<jats:p><h2>Abstract</h2><p>Chemical recycling of nonbiodegradable postconsumer polymers represents a promising route for conversion of waste plastics into feedstock for fuel, chemicals and materials production. Recently, waste plastics have been used as low cost feedstock for carbon nanotubes growth. In this work thermal behavior of multiwalled carbon nanotubes material (MWCNTs), obtained by catalytic pyrolysis of waste low-density polyethylene, has been analyzed. Following the improved protocol, developed few years ago for thermal analysis of CNTs, thermogravimetric analysis of the MWCNTs material has been performed using heating rates of 2-20 <sup>o</sup>C<sup>.</sup>min<sup>-1</sup> and curve fitting method in an attempt to quantify the complex oxidation behavior of the material. It has been shown that competitive oxidation/combustion processes greatly influence the DTG curves and the number of fitted peaks.</p></jats:p> - Some of the metrics are blocked by yourconsent settings
Item type:Publication, Upcycling of plastic waste into multi-walled carbon nanotubes as efficient organic dye adsorbent(Slovenian Chemical Society, 2025-03-03); ; Kovačič, SebastijanMulti-walled CNTs with an average diameter of about 80 nm, a length of several micrometers and surface area (SBET) of 100 m2 g-1 were obtained by pyrolysis of low-density polyethylene waste. The potential of the resulting MWCNTs material to purify water containing organic dyes was tested with Bezaktiv Blau HE-RM (BB) and Bezaktiv Rot S-3B (BR) reactive dyes. 200 mg L-1 MWCNT material was used to follow the adsorption of 30 mg L-1, 40 mg L-1, 50 mg L-1 and 60 mg L-1 BB and BR at pH 3 and a temperature of ~25 oC. The results have shown that this material has a high potential as a sorbent, and its adsorption capacity of 257 mg g-1 (for Bezaktiv Blau HE-RM) and 213 mg g-1 (for Bezaktiv Rot) is close to some commercial MWCNTs and functionalized MWCNT-based adsorbents. The adsorption process was very fast, reaching 80-90 % of the dye removal in 10-15 minutes, and the equilibrium time was reached in 40-60 minutes. The adsorption isotherm showed that the Langmuir model was more suitable than the Freundlich model for describing the adsorption properties of the pollutants. - Some of the metrics are blocked by yourconsent settings
Item type:Publication, Vibrational spectra of Cs2CaCl4·2H2O(Elsevier BV, 2011-03) - Some of the metrics are blocked by yourconsent settings
Item type:Publication, The correlation between structure and β-nucleation efficiency of Ba, Sr, Ca and Mg pimelates in isotactic polypropylene(Society of Chemists and Technologists of Macedonia, 2015-05-05); <jats:p><p>The pimelates of the earth-alkaline elements and pimelic acid have been synthesized and studied. All prepared pimelates are crystallohydrates and Ba and Sr pimelates are isotypic. The obtained compounds have been characterized using infrared spectroscopy and X-ray diffraction, and it was found that, near and above the melting temperature of polypropylene, the pimelates of Ba and Sr are crystalline, whereas the ones of Ca and Mg are amorphous. The nucleation activity of these pimelates has been studied in the process of crystallization of polypropylene in non-isothermal conditions and followed by differential scanning calorimetry (at cooling rate <em>V</em><sub>c </sub>= 1–20 K min<sup>–1</sup>). It was found that their nucleation activity, even at concentration of 0.1 %, differs considerably with regards to the cooling rate, and they induce different polymorphic composition of the polymer. The nucleation activity was mostly exhibited by Ca pimelate, and when it was used the content of the β crystalline phase (<em>U</em><sub>β</sub>) in polypropylene ranged from 0.90 to 0.94, depending on the cooling rate, compared to 0.18–0.35 when Mg pimelate was used. In the polymer crystallized by using Ba and Sr pimelate as nucleators, <em>U</em><sub>β</sub> ranged from 0.47 to 0.77. Based on the theoretical concepts for nucleation activity of solid substrates, an attempt was made to correlate the structurаl features of the synthesized pimelates with their β-nucleation activity in the process of nonisothermal crystallization of iPP.</p></jats:p> - Some of the metrics are blocked by yourconsent settings
Item type:Publication, Thermal behavior of acid phosphate salts Ca2MH7(PO4)4⋅2H2O (M = K+, NH4 +) and CaK3H(PO4)2(Elsevier, 2023-06); New knowledge about various aspects of little-known acid salts is of great scientific and practical importance in view of their potential application in different areas such as proton conductors. For the first time, the thermal behavior of three acid phosphate salts, dicalcium potassium heptahydrogen tetrakis(phosphate) dihydrate (Ca2KH7(PO4)4⋅2H2O), dicalcium ammonium heptahydrogen tetrakis(phosphate) dihydrate (Ca2(NH4)H7(PO4)4⋅2H2O) and calcium tripotassium hydrogenbis(phosphate) (CaK3H(PO4)2), has been investigated. By means of simultaneous thermogravimetry, differential thermal and mass spectrometry analyses (TG/DTA/MS) he schemes of their thermal decomposition have been proposed. The two isostructural compounds Ca2KH7(PO4)4⋅2H2O and Ca2(NH4)H7(PO4)4⋅2H2O are stable up to 90 – 95 ◦C and then undergo multiple-steps thermal decomposition process owing to dehydration of the crystallization water and dehydration-condensation. The anhydrous salt CaK3H(PO4)2 exhibits very high thermal stability up to 530 ◦C. The products of the thermal decomposition have been identified.