Irena Michailova

Irena Michailova
University of Chemical Technology and Metallurgy | UCTM · Department Technology of Silicates

Associate professor

About

66
Publications
29,655
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367
Citations
Citations since 2017
22 Research Items
214 Citations
201720182019202020212022202301020304050
201720182019202020212022202301020304050
201720182019202020212022202301020304050
201720182019202020212022202301020304050
Introduction
Current research interests: Mineral synthesis and characterization, crystalline structure, phase analysis, microstructure; Research of systems of practical importance; Mineralogy of industrial waste (copper slags, blast furnace slags); Utilization of industrial waste and natural resources (slag's glass-ceramic etc.); Synthesis and structural characterization of new materials for various applications (catalysts, biomaterials etc.)

Publications

Publications (66)
Article
The high temperature synthesis of glasses in the system (100‐x)(0.16Na2O/0.10CaO/0.74SiO2)/xFe2O3, x = 5 ÷ 20 mol% is reported. For Fe2O3 concentrations ≤ 15 mol%, glasses are formed while the sample with 20 mol% crystallizes during cooling the melt. X‐ray diffraction shows the crystallization of magnetite. The microstructure of the glass‐crystalli...
Article
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It is carried out an overview of current European strategic documents regulating the guidelines for transition to a green, resource-efficient and competitive economy. The main place is given to industry and power engineering. It is pointed out that the elimination of the existing problems in these branches requires the most serious concentration of...
Article
Peculiarities of mechanically assisted thermal synthesis of cuprorivaite (CaCuSi4O10) were described. For the sake of comparison, the classical thermal synthesis of the same product was performed using the same reagents. X‒ray diffraction (XRD) method was used to characterize the products obtained. Phase changes were registered as a result of the m...
Article
Lately silver has become extremely important among alloying additives used to produce glassy materials with specific tailored properties. The aim of the study is to characterize bioactive glasses belonging to the CaO–SiO2–P2O5–Ag2O system by SEM and EDX methods, as well as biocomposites based on natural rubber containing those fillers. The focus is...
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One of the important issues of the modern world is the ecological problems, which raise the issues of rational and efficient use of natural resources and the reduction of industrial waste. Materials synthesized from industrial waste are an example of producing new useful materials for various applications as well as efficient utilization of waste....
Article
Glass-ceramics with cubic BaTiO3 as a major and hexagonal BaTi1-xFexO3-δ as a second phase were prepared by crystallization at 560°C in a glass with the composition 20.1Na2O/23TiO2/23.1BaO/3Al2O3/7.6B2O3/17.4SiO2/5.8Fe2O3. X-ray photoelectron spectroscopy revealed presence of Ti⁴⁺ and Fe³⁺ ions in tetrahedral and octahedral coordination. Ba²⁺ occur...
Article
Glass ceramics from the CaO–P 2 O 5 –SiO 2 system were synthesized. They were characterized by XRD, SEM and EDX methods. It was found that they contain two crystalline [Whitlockite, Ca 3 (PO 4 ) 2 and Hydroxylapatite, Ca 5 (PO 4 ) 3 (OH)] and one residual amorphous phase. The ceramics are composed of porous aggregates of fine particles with predomi...
Chapter
Glasses are synthesized in the system Na2O/BaO/TiO2/SiO2/B2O3/Al2O3 for different Na2O/Al2O3 ratios. X-ray photoelectron spectroscopy is utilized for the estimation of the valence states of titanium and the occurrence of solely Ti4+ is observed. The presence of bonds from the type Si-O-Al, Si-O-Si and Na-O-Si is detected in the glasses and it is co...
Chapter
Barium titanate is synthesized by sol-gel and hydrothermal methods. The sol-gel technique allows the preparation of amorphous powders which are subsequently subjected to appropriate time-temperature programs and barium titanate is precipitated. The allotropic modification of the barium titanate from the obtained sol-gel powder depends on the temper...
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ABSTRACT: Metallurgical slag is known to be a significant part of solid industrial waste. Although various opportunities are being sought for their utilization, large quantities of metallurgical slags are practically landfilled. The purpose of this study is to synthesize glass ceramics based on waste copper slag. Fayalite waste is obtained after fl...
Article
A number of properties of natural rubber-based composites containing fillers of sol–gel glasses and ceramics from the CaO–SiO2–P2O5 system were investigated and compared. Its goals were to evaluate and select more suitable usages in flexible electronics, in particular as substrates and insulating layers in antennas for wireless communications. The...
Article
Bioactive glass was first synthesized by L. Hench in 1971. There are many studies on the properties of several metals and metal ions dopants used in the SiO2‐CaO‐P2O5 system of bioglasses, such as Ag, Cu, Zn, and Fe. A number of authors have carried out research related to the influence of silver oxide on the properties of bioglasses. However, publ...
Article
Here we studied the mechanically-assisted synthesis of mixed nickel-copper oxides at the temperature range of 600–1000 ◦C. Nickel and copper oxalates have been used as starting materials and the mechanical treatment has been prolonged up to 5 h using planetary ball mill. The XRD analysis shows for- mation of NiO-CuO and CuO-NiO solid solutions. As...
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The purpose of this study was to investigate the prospective use of calcareous clay in its natural state and after thermal treatment for removal of heavy metals from aquatic environment. The study included 6 natural products from clay deposits in Bulgaria, five of which were calcareous clays and the sixth one was an iron-rich clay. The structural c...
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Ceramics with chemical composition corresponding to åkermanite (2CaO.MgO.2SiO 2) was synthesized by using sol gel technique. The obtained dried gel was subjected to a two-step thermal treatment firstly at 700 °C for 2 hours and then at 1000, 1100, 1300 °C respectively for 2 hours. X-ray diffraction showed the temperature dependent structure evoluti...
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Abstract The research work presents Cu-Ni oxide catalysts, deposited on γ-Al2O3 support and thereafter calcined at various temperatures: 400 ◦C, 500 ◦C, 600 ◦C and 700 ◦C. The catalyst samples have been prepared by the impregnation method using aqueous solutions of nitrates, containing Cu and Ni. The catalysts have been characterized by means of X-...
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Bioactive composite materials were prepared by mixing 20 wt.% of silk fibroin (SF) and 80 wt.% of glassceramics from CaO-SiO2-P2O5-MgO system. In vitro bioactivity of the prepared composites was evaluated in 1.5 simulated body fluid (1.5 SBF) in static conditions. The obtained samples before and after in vitro tests were characterized by X-ray diff...
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ABSTRACT The study examines the phase composition and structure of fayalite waste (FW), as well as the changes that occur during heat treatment applied in the temperature range of 500 - 1000 °C. Differential thermal analysis, X-Ray diffraction analysis, Fourier transform infrared spectroscopy, Optical microscopy, Scanning electron microscopy and En...
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Abstract : The main purpose of the presented article is the preparation and evaluation of carbonate apatite formation on the sol-gel glasses in SiO2-CaO-P2O5-xAg2O system, where x=0, 1, 2 and 4 wt.% Ag2O, after soaking in 1.5 SBF solutions for 12 days in static conditions. The investigated samples were prepared via the polystep sol-gel method and t...
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The main objectives of the presented study is the preparation of 80BG/20G (in wt. %) composites between sol-gel glasses (BG) in the SiO2-CaOP2O5-xAg2O (x=0, 1, 2 and 4 wt. %) system and gelatin (G), after soaking in 1.5 SBF solutions for 12 days in static conditions. The structure and in vitro bioactivity of the prepared composites were examined by...
Article
Biphasic CuO–NiO solids were synthesised using mechanical activation and thermal treatment of a mixture of nickel oxalate and copper oxalate at different temperatures (400, 500, 600 and 700°C). XRD analysis identified two crystalline phases in the samples with the structures of CuO Tenorite and NiO Bunsenite, accordingly. A change in the catalytic...
Article
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The main purpose of the presented article is the preparation of novel glass-ceramics in CaO-SiO2-P2O5-MgO system and evaluation of carbonate apatite formation after soaking in TRIS-HCl buffer solution for 14 days. The investigated samples were prepared via sol-gel method and structure of the obtained samples was studied using XRD, FTIR, SEM, XPS an...
Article
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Materials with a high specific surface area (329-621 m2/g) were synthesized by modification of blast furnace slag. The process included chemical and thermal treatment. Four samples were obtained as the chemical treatment was conducted at various values of pH. ICP-OES, XRD, FTIR, SEM, BET-analysis and other methods were applied for phase and structu...
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In order to check to what extent the slag-based glass-ceramics may be used as carriers in the preparation of active supported catalysts, copper-cobalt oxide catalysts on different carriers (glass-ceramics obtained :on the basis of blast furnace slag) were studied. The catalytic activity towards the complete oxidation of carbon monoxide was evaluate...
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The ceramics in the system CaO-MgO-SiO2 has recently received a great deal of attention because they exhibit good in vitro bioactivity and have potential use as bone implants. Biphasic calcium-magnesium-silicate ceramics was prepared by a sol-gel method. The dried gel with chemical composition 3CaO.MgO.2SiO(2) was thermally treated at 1300 degrees...
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Several types of glass-ceramics in the CaO-MgO-SiO 2 system are shown to be bioactive, biocompatible and exhibiting various advantages for bone regeneration. A polyphase calcium-magnesium-silicate glass-ceramics is prepared by the sol-gel method including a two-step thermal treatment procedure aiming to investigate the effect of its phase compositi...
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The effect of autoclaving of the granulated blast furnace slag on its catalytic activity with regard to the oxidation of CO was investigated. The results show that autoclaving after chemical treatment of slag with nitric acid or nitric acid and ammonia, leads to the increase in the specific surface area, but reduces the concentration of catalytical...
Article
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The present work is devoted to the mechanically assisted thermal synthesis of copper oxide nickel oxide mixtures obtained from copper and nickel oxalate precursors and to their catalytic properties towards oxidation of CO. DTA/DTG methods are used to show the effect of the mechanical activation on the thermal decomposition of copper and nickel oxal...
Article
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The ability to create new active catalysts for complete oxidation of carbon monoxide and organic compounds on the basis of the metallurgical slag for waste gas purification was proven. The procedure for the synthesis of the catalysts includes only acid and thermal activation of the metallurgical slag, during which in addition to increasing the cata...
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In the present work Polyurethane (PU)/Bioglass (BG) composite materials were synthesized with different content of BG (10 and 20 mol.%) as filler. The 85S Bioglass was synthesized via polystep sol-gel method. The chemical composition of BG is 85SiO2-10CaO-5P2O5 (wt.%). The synthesis of PU was carried out by a two-step polyaddition reaction. The 85S...
Article
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The aim of this study is to evaluate the possibilities for improving the adsorption capacity of blast furnace slag in processes for removal of heavy metal ions from aqueous media. Three samples of slag have been prepared by heating of granulated blast furnace slag. The initial slag and thermally treated slag samples have been characterized using X-...
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A series of Polycaprolactone and Bioglass in the 85SiO 2-10CaO-5P2O 5 (mol. %) systems were synthesized at different quantity of the organic/inorganic co mponents. The 85S Bioglass was prepared via sol-gel method. It was added to the Polycaprolactone matrix at 20, 50 and 80 weight (wt.) %, respectively. In vitro bioactivity of the prepared composit...
Article
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The influence of the crystallization and the mineral composition on the adsorption properties of slag-based glass ceramics has been studied with respect to lead ions. Four slag-ceramic samples have been prepared by sintercrystallization process of pressed glass powders. All samples have been characterized by XRD, FTIR and SEM analyses and lead batc...
Article
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In this work we present the experimental results on synthesis structure and in vitro bioactivity of collagen (C)/calcium phosphate silicate (CPS)/chondroitin sulfate (ChS) composites with C/CPS ratio of 25:75 wt. % and 75:25wt. %. The synthesized composites were characterized by XRD, FTIR and SEM/EDS. XRD and FTIR before in vitro test proved that t...
Article
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The phase composition of the depositions formed in the radiation section of the waste heat boiler utilizer (RS of WHB) after injecting sulphatizing flow in the volume of the off-gases from the uptake of flash smelting furnace for copper sulphide concentrate smelting was studied. With the help of X-ray diffraction (XRD), Reflected-light microscopy a...
Article
The catalytic activity of Ca2CoSi2O7 (I) and CaCoSi2O6 (II) in oxidation reactions of CO and toluene is examined.
Article
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The main purpose of the presented article is to study the structural features and catalytic activity Of Co 2TiO 4 spinel, synthesised via sol-gel method. Two variants of the sol-gel route were used for the synthesis Of Co 2TiO 4 spinel. For comparison, spinel Zn 2TiO 4WaS also synthesised and studied. The synthesised samples were characterised usin...
Article
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A study was conducted of the adsorption capacity of slag samples obtained by crystallization of granulated blast furnace slag with and without Al 2O 3 and MgO additions in aqueous solutions of Cu (II), and a comparison was made between the original amorphous slag and the synthesized samples with main phases gehlenite and åkermanite. The purpose of...
Article
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In this work we present the experimental results on synthesis, structure evolution and in vitro bioactivity of col-lagen-silicocarnotite-chondroitin sulphate composites. The obtained samples were synthesised by mixing col-lagen (C) and silicocarnotite (S) powder with C:S ratio of 75:25 and 25:75 wt.% in the presence of chondroitin sulphate (ChS). C...
Article
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Two calcium–cobalt silicates were synthesized in which cobalt occupies different structural positions. The crystal phases belong to two main structural silicate types. In the Co-åkermanite structure (Ca2CoSi2O7), cobalt cations take tetrahedral coordination toward oxygen atoms. In the Co-pyroxene structure of CaCoSi2O6, cobalt displays octahedral c...
Article
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The aim of the present study is to examine the catalytic activity of two types of copper slag – flash smelting furnace slag (FS) and converter slag (CS). Two typical slag compositions different in chemical composition and way of production were selected, in order to clarify how these differences affect their catalytic properties. The analysis of th...
Article
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Glass-ceramics manufacturing has been considered as a very effective method for recycling and utilizing different types of industrial wastes. The purpose of this paper was to investigate the crystallization process of sintered glass-ceramics prepared from vitrified mixtures which were composed on blast furnace slag (68–80 % mass), kaolin, Al 2 O 3...
Article
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Minimization and utilization of industrial wastes as secondary raw material resources is essential to achieve sustainable technologies. This work presents the results of a study of the properties of ash resulting from combustion and industrial processes in the complex "Svilosa"in Svishtov. Using appropriate analysis and physico-chemical techniques,...
Article
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The main purpose of the paper is the evaluation of the influence of chemical composition of the gel of the synthesized 15CaO·0.5P2O5·6SiO2 glass-ceramic on the structure, crystallization behaviour and in vitro bioactivity in static conditions for different periods of time - 3, 9 and 30 days in 1.5SBF. The obtained glass-ceramic was synthesized via...
Article
Full-text available
The aim of the present study was to characterize the fayalite crystal phases in two types of copper slag – flash smelting furnace slag (FS) and converter (CS) slag, given their possible use in adsorption and catalytic processes. Two typical slag compositions different in chemical composition and way of production were selected, in order to clarify...
Article
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In this work we present experimental results about synthesis, structure evolution and in vitro bioactivity of new calcium phosphate silicate/wollastonite (CPS/W) glass-ceramics. The samples obtained were synthesized via polystep sol-gel process with different Ca/P+Si molar ratio (R). The structure of the materials obtained was studied by XRD, FTIR...
Article
Full-text available
Ceramics, with basic composition based on the CaO-SiO2-P2O5-MgO system with different Ca+ Mg/P+Si molar ratio (R), were prepared via polystep sol-gel technique. The structure of the obtained ceramic materials has been studied by XRD, FTIR spectroscopy, and SEM. X-ray diffraction showed the presence of akermanite and HA for the sample with R = 1.68...
Article
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In the present work the results of the research on the sol-gel synthesis and structure of cordierite (2MgO·2Al2O3·5SiO2), tialite (Al2O3·TiO2) and cordierite/tialite glass-ceramics as well cordierite containing 2 wt.% of Co and Co+Cu have been described and discussed. The sol-gel synthesis was carried out using different kind of precursors as follo...
Article
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The present study aims to determine the nature and origin of foreign crystal inclusions in container glass produced within the period July – November 2008. A crystal-optical method, X-ray diffraction analysis (XRD) and electron probe microanalysis (EPMA) were applied. Several types of inclusions (defects) were found and studied and characterized by...
Conference Paper
Full-text available
In the presented article the actual (2006-2009) chemical and phase composition and microstructure of the metallurgical converter copper slags have been examined. A mineralogical characterization of converter slags, using chemical analyses, X-ray diffraction (XRD), reflected light microscopy, Elecron probe Micro Analysis (EPMA), was made. The minera...
Conference Paper
Full-text available
In the presented article the actual (2006-2009) chemical, phase composition and microstructure of the metallurgical smelter copper slags have been investigated. A mineralogical characterization of flash smelting slags, using chemical analyses, X-ray diffraction (XRD), reflected light microscopy, Electron Probe Micro Analysis (EPMA), was made. The c...
Conference Paper
Full-text available
The aim of the present study is to synthesize and study calcium-cobalt silicates: Ca 2 CoSi 2 O 7 and CaCoSi 2 O 6 , which are structural analogues of akermanite and diopside minerals in the full substitution of the positions of magnesium with cobalt. The shown phases have been determined in the system CaO–CoO–SiO 2. The chosen crystal phases belon...
Article
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LaCoO3 powders are studied because they exhibit interesting electrical, magnetic and catalytic properties. In this paper, new synthesized La2O3-CoO-SiO2 powders with different quantity of silica were prepared via solgel method in aqua media, starting from metal nitrates with different chelating agents. The relation between the reaction in solution,...
Article
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A new phase in the system BaO-MnO-SiO2 obtained by a pyrosynthetic method has been investigated using selected area electron diffraction (SAED), electron probe microanalysis (EPMA), and X-ray powder diffraction. The lattice parameters and a possible space group of the phase with a general composition BaMnSiO4 were determined as follows: a=5.370(2),...
Article
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A new phase in the system BaO–MnO–SiO2 obtained by a pyrosynthetic method has been inves- tigated using electron microprobe analysis (EPMA), X-ray powder diffraction (PDA), and trans- mission electron diffraction. The lattice parameters and possible space group of the phase with a general composition BaMnSi2O6 were determined as follows: a=13.896,...
Article
Full-text available
Glasses corresponding in composition to BaMnSiO4 and BaMnSi2O6 crystalline phases synthesized previously, have been obtained in the region with low SiO2 content of the BaO-MnO-SiO2 system. The glass structures were investigated by electron spin resonance, ultraviolet-visible and infrared spectroscopy, X-ray diffraction methods, etc. The trend to a...
Article
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A new compound—Ba3MnSi2O8 in the system BaO–MnO–SiO2 was synthesized and studied by powder X-ray diffraction. The compound is hexagonal, space group—P6/mmm, a=5.67077 Å, c=7.30529 Å, Z=1, Dx=5.353. The obtained powder X-ray diffractometry (XRD) data were interpreted by the Powder Data Interpretation Package.

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