Irena Markovska

Irena Markovska
Bourgas "Prof. Assen Zlatarov" University · Silicate Technology

Professor

About

159
Publications
46,181
Reads
How we measure 'reads'
A 'read' is counted each time someone views a publication summary (such as the title, abstract, and list of authors), clicks on a figure, or views or downloads the full-text. Learn more
476
Citations
Introduction
Irena Georgieva Markovska currently works in prof. Assen Zlatarov University, Bugras, Bulgaria (Silicate Technology Department). Areas of scientific interest: synthesis of graphene, synthesis of ceramic pigments; synthesis of corundum ceramic materials; obtaining of wear resistant ceramic materials and composite materials; development of ceramic composites; utilisation of waste materials, obtaining of glass and class- ceramics, obtaining of ceramic fractal systems
Additional affiliations
January 1998 - present
Bourgas "Prof. Assen Zlatarov" University
Position
  • Professor

Publications

Publications (159)
Article
Full-text available
Garnet ceramic pigments were synthesized by the method of solid-phase sintering. The starting materials are pure oxides: CaO, SiO2.nH2O. The following elements have been added as chromophores: V, Fe dnd Cr. For this purpose, the following raw materials were used: NH4VO3, Fe2O3 and K2Gr2O7. The pigments were synthesized at a final firing temperature...
Article
Full-text available
This study presents kinetics of oxidation of copper pyro-metallurgical iron silicate (fayalite) slag, studied by TG-DTA, XRD and SEM-EDS analyses. The result from the analysis in the paper will be used for developing a method for oxidation of copper slag using fluid bad technology. For this purpose, oxidation kinetics are investigated with differen...
Article
Full-text available
Abstract. The object of the present study is investigation of possibility of obtaining zircon ceramic pigments by utilising a widespread bio-waste – rice husk. Rice husk ash was used as a source of SiO2. The preparation of high temperature ceramic pigments using colourless stable crystal carcasses turns out to be quite suitable method in the case o...
Article
Full-text available
Background This paper proposes a technology for the production of monolayer graphene by an easy, accessible, and non-toxic method. Methods For the preparation of graphene, a combination of chemical and physical (ultrasonic) treatment of the original graphite precursor (purity >99%) was applied. The precursor of graphite is placed in a beaker with...
Article
Full-text available
The aim of paper the synthesis of new garnet ceramic pigments. The blend preparedwas ground in a ball mill and subjected to heat treatment. Green ceramic pigments were synthesized at 800°C-1200°C. The optimal temperature for the synthesis and the most appropriate mineralizer were defined. The phases established by X-ray diffraction and infrared spe...
Article
Full-text available
The sol-gel synthesis of BaTiO 3 powder was performed using a modified Pechini method. In sol gel synthesis, the conditions are significantly milder than in direct solid phase synthesis. The sol-gel synthesis was performed using BaCl 2 and TiCl 3 as starting materials. The synthesis temperature was 850°C with termal soaking of 2 hours. Finely dispe...
Article
Full-text available
Zirconium ceramic pigments with basic zircon phase-ZrO2.SiO2 were synthesized by solid phase sintering of pure oxides: ZrO2, SiO2.nH2O, and the following elements were added as colorants: V, Fe, Cr, Co and Mn. NH4Cl was used as a mineralizer. The pigments were synthesized at three final firing temperatures: 1000, 1100 and 1200 ° C. The color charac...
Article
Full-text available
A technology for synthesis of barium titanate ceramics with high dielectric constant is proposed. In present work a sol-gel method was used for BaTiO3 synthesis. Different mixtures have been studied and the technological regimes for obtaining a quality ceramic structure with high dielectric constant have been optimized. This ceramics could find app...
Article
Full-text available
Graphene is an amazing material, with many potential applications, that continues to impress scientists around the world with its structure and composition. Graphene also opens up many possibilities in electronics. One of the areas for which graphene is studied and developed is to be used in the supercapacitor's manufacture. Graphene is known as th...
Article
Full-text available
This work focuses on the syntheses of willemite ceramic pigments doped with cobalt and nickel ions (Co ²⁺ , Ni ²⁺ ). The pigments were prepared by the sol−gel process. The phase formation has been studied by X - ray diffraction analysis. The results showed that phase composition depends on sintering temperature, isothermal retention period as well...
Article
Full-text available
In recent years the interest of using of foam glass produced from glass microspheres in various fields of industry has been increased. In the present work the samples of foam glass were synthesized. As raw materials two types of factory glass microspheres (Sigma-Aldrich) were used, respectively with a diameter of fraction of 212-300 μm (50-70 US si...
Article
Full-text available
Synthesis of fractal materials from wollastonite ceramics: Amorphous CaSiO 3 powders were prepared through a chemical precipitation method and β-CaSiO 3 ceramics were fabricated. The ceramic samples were sintered at 1300°C for 60min. The wollastonite ceramic powders were characterized mainly by X-ray diffraction, thermal analysis and FTIR studies....
Article
Full-text available
In this study the adsorption of Cu (II) ions from aqueous solutions on synthetic zeolite NaA was evaluated. The effect of solution temperature and the determination of the kinetic parameters of adsorption of Cu(II) from aqueous solution on zeolite NaA is important in understanding the adsorption mechanism. Variables of the system include adsorption...
Article
Full-text available
The crystallization kinetics and phase transformation of SiO 2 .Al 2 O 3 .0,56P 2 O 5 .1,8CaO.0,56CaF 2 glass have been investigated using differential thermal analysis (DTA), x-ray diffraction (XRD), and scanning electron microscopy (SEM). Glass samples were obtained by melting the glass mixture at 1450 0 С/120 min. in platinum crucibles. The mixt...
Conference Paper
Full-text available
A prototype model of an emulsion separator was designed and manufactured. Generally, it is a cylinder filled with different fractal modules. The emulsion was fed into the reactor by a peristaltic pump through an inlet placed at the boundary between the two phases. For hydrodynamic design and sizing of the reactor the assumptions of the theory of fi...
Article
Full-text available
The present research focus on the processing of mullite-based ceramics from oil refinery industrial wastes and by-products of agricultural industry and on the investigating of silane modified surface of ceramics. Two waste products were used as initial material-waste aluminum oxide and waste rice husk. The burning-out additives used were waste rise...
Article
Full-text available
One Possibility for utilization of waste soot: The paper represents one useful possibility for salvage of waste soot. After forming the salvage by decomposition of hydrocarbons the soot particle size are 9 to 600 microns great. This size is not appropriate for use in the industry. The paper describes the next stages of treatment of the soot, so tha...
Article
Full-text available
Study of properties of composite materials reinforced with glass fibers and microspheres in an organic matrix: Developed composites based organic matrix. As of raw materials used polyester resin-matrix, glass beads-as a secondary phase and glass fiber-reinforced components. The introduction of the glass microspheres in the polyester matrix leads to...
Article
Full-text available
81-Влияние на някои фактори върху разделянето на емулсия от типа вода-масло. Част I. Изследване на омокрящата способност на някои течности И. Марковска, Н. Зайтцев, Б. Богданов, Д. Георгиев, Я. Христов Influence of some factors on the separation of an emulsion of oil-water type. Part I. Investigation on the wet ability of some liquids: This work de...
Article
Full-text available
87-Влияние на някои фактори върху разделянето на емулсия от типа вода-масло. Част II. Разделяне в реактор с пълнеж от целулоза и памук И. Марковска, Н. Зайтцев, Б. Богданов, Д. Георгиев, Я. Христов Influence of some factors on the separation of an emulsion of oil-water type. Part II. Separation in a reactor filled with cellulose and cotton: In the...
Article
Full-text available
btaining of lightweight geopolymer using ash from thermal power plants: A lightweight inorganic polymer is obtained using ash from thermal power plants, metakaolinite and lightweight aggregate. This inorganic material is activated using small amounts of sodium hydroxide and sodium silicate solution. Processing parameters and various curing conditio...
Article
Full-text available
Porous material of phosphate-based geopolymer : The aim of the present work is obtaining of porous geopolymer, synthesized from metakaolin, α-Al 2 O 3 , Al powder and phosphoric acid at 85 °C for 4 h. The α-Al 2 O 3 obtaining from waste alumina. The Al powder served as a foaming agent to control porosity, pore size and pore distribution producing a...
Article
Full-text available
A Pseudo second-order kinetic model for the sorption of Cu(II) ions in aqueous solutions of Zeolite NaA: In this study, the sorption of Cu(II) ions in aqueous solutions of Zeolite NaA by performing batch kinetic sorption experiments. The equilibrium kinetic data were analyzed using the pseudo-second-order kinetic model. A comparison was made of the...
Article
Full-text available
Dielectric material is an important part of condenser components. The present work reports the synthesis of high porosity dielectric ceramics with a main phase of mullite. Burned rice husk ash was used as a pore-forming agent. γ-Al2O3, technological waste from the petrochemical industry, was used as the basic material. Additive of 3% TiO 2 was adde...
Article
Full-text available
This paper proposes a technology for the production of monolayer graphene (from 1 to 5 layers) by an easy, accessible and non-toxic method. For the preparation of graphene, a combination of chemical and physical (ultrasonic) treatment of the original graphite precursor (>99%) was applied. During the treatment with dilute sulfuric acid, the Vanderva...
Article
Full-text available
Synthesis and study of spinel ceramic pigments in the system CoO.ZnO.Al2O3: The aim of paper the synthesis of new spinel ceramic pigments. The blend preparedwas ground in a ball mill and subjected to heat treatment. Spinel ceramic pigments were synthesized at 800°C-1200°C. The optimal temperature for the synthesis and the most appropriate mineraliz...
Article
Full-text available
The synthesis of ferrum-willemite ceramic pigments in the system xFeO(2-x)ZnOSiO 2 (where x=0.125-1.00) was investigated in this work. The results of colorimetric measurements (in the system CIEL * a * b *) showed that the concentration of iron(II) oxide in the composition of 0.25 mol is sufficient for preparation of ceramic pigments of red-brown...
Article
Full-text available
The present work proposes a technology for obtaining of graphene and its deposition as nanolayer onto aluminium substrate. The essence of the technology is the deposition of nano-graphene coating onto the electrically conductive part of the electrode by generation of high-voltage discharge between the main metal layer and the carbon electrode. For...
Conference Paper
Full-text available
The aim of the present paper is to study the possibilities to synthesize willemite ceramic pigments with respect to their possible use as pigments in the silicate industry. The preparation of high temperature ceramic pigments using colorless stable crystal carcasses turns out to be quite a suitable method in order to its colored by introducing diff...
Conference Paper
Full-text available
This work focuses on the syntheses of colored willemite ceramic pigments. The pigments were prepared by solid phase sintering technology. The paper reports experiments carried out on the synthesis of willemite pigments doped with ions of transition elements as well as iron, manganese and vanadium. The sintering temperatures were between 900 and 1 2...
Article
Full-text available
The possibility of synthesizing manganese-willemite ceramic pigments in the system xMnO · (2 – x)ZnO · SiO2 (x = 0.125; 0.250; 0.375; 0.500; 0.625; 0.750; 0.875 and 1.00) was studied. Manganese-willemite ceramic pigments were synthesized at 800 – 1200°C. The obtained pigments were investigated by means of x-ray phase analysis, electron paramagnetic...
Article
Full-text available
This study shows the possibility to synthesis ceramic pigments via solid-state high temperature sintering. The preparation of high temperature ceramic pigments using colourless stable crystal carcasses turns out to be quite suitable method in the case of ZrSiO 4 and their colouring by introducing different chromophores. The paper reports for experi...
Article
Full-text available
This study shows the possibility to synthesisze ceramic pigments via solid-state high temperature sintering. Willemite ceramic pigments, doped with Co and Ni as well as Fe-Zn spinel ceramic pigments were synthesized. The starting materials used for the synthesis are CoO, ZnO, CoO, Fe 2 O 3 , NiO and SiO 2 obtained from bio waste-rice husk ash. The...
Article
Full-text available
In this study willemite ceramic pigments, doped with Ni were synthesized. The optimal parameters of the synthesis process have been determined. The willemite is a mineral (zinc silicate) with formula Zn 2 SiO 4. For the production of willemite ceramic pigments in the system NiO-ZnO-SiO 2 we have used the following main materials: ZnO, NiO and SiO 2...
Article
It is believed that graphene is a next-generation conducting material with the potential to be used for obtaining of electrodes for supercapacitors. The object of the present study is investigation of possibility of obtain low cost and ecofriendly graphene and study of its properties as material for supercapacitor electrodes. A combination of chemi...
Article
Full-text available
The purpose of this study is to present one of the possible methods for assessing the roughness of ceramics surface based on its digital image. A porous ceramic materials for filtration purpose having open porosities up to 65.84 % are synthesized. X-ray analysis carried out shows that the ceramics main phases refer to corundum, gelenite and calcium...
Article
Full-text available
Porous ceramics were synthesized with open porosities of up to 65.84 %. The porosity was achieved mainly by thermal dissociation of CaCO 3 and graphite burning. The main phases observed in the compositions of the highest porosity were as follows: corundum, gelenite and calcium-aluminate. The values of the coefficient of fractal dimension (D) of the...
Preprint
Full-text available
CITATIONS 0 READS 2 4 authors, including: Some of the authors of this publication are also working on these related projects: Contract № DO-02-192 /2008 "Elaborating of compositions, installation and technology for obtaining porous silicate materials from local natural materials and waste products" View project Contract № DDVU 02-106 /2010, subject...
Article
Full-text available
The present research focus on the processing of mullite-based ceramics from oil refinery industrial wastes and by-products of agricultural industry and on the investigating of silane modified surface of ceramics. Two waste products were used as initial material-waste aluminum oxide and waste rice husk. The burning-out additives used were waste rise...
Article
Full-text available
Stainless steel Metal Matrix Composites with SiC and TiC content, particularly applicable for high wear resistant applications, are to be discussed in the present paper: Metal composite materials (including composites with metal matrix-Metal-matrix composites /MMCs/) with carbide containing mixture on the surface layer are particularly suited in th...
Article
Full-text available
The present paper deals with problems related to the possibilities to use fractal systems to solve some important scientific and practical problems connected with filtering and separation of aqueous phases from organic ones. For this purpose a special separator have been designed. The reactor was filled with a porous material with fractal dimension...
Article
Full-text available
The present paper reports the removal of Cd(II) and Zn(II) ions using synthetic Zeolit NaA. The adsorption capacity of the sorbent (Zeolite NaA) strongly depends on simultaneous or not simultaneous (concurrent) presence of Cd(II) and Zn(II) in the sorbate. When Cd(II) and Zn(II) are present simultaneously (concurrently) in the sorbate, Zn(II) ions...
Article
Full-text available
New design of a grid for preparation of high density granules with enhanced mechanical strength by granulation of dispersed materials is suggested. A method for hydrodynamic dimensioning of the grid depending on granulation conditions, hydrodynamic regime of the operation, dispersity and physicochemical characteristics of the materials to be granul...
Article
Full-text available
A newly designed gas-distributor for granulation of powdery materials in equilibrated fluidized bed and a system for collecting the granules prepared are suggested. The aim of these designs is to solve the problems arising by the granulation of powdery materials in fluidized bed devices. The gas-distributor and the collection system proved to be re...
Article
Full-text available
In the present paper the possibility of wastewater's purification with natural zeolite of the clinoptilolite type was examined. The waste water from industrial companies was polluted whit COD, BOD5 and fats. The zeolite used was produced from the field in Beli Plast, NorthEast Rodopi Mountain. In the experiment described, zeolite has subjected to m...
Article
Full-text available
The demand of alternative building materials and their quality is now responsible task in which it is necessary to resolve problems related to technological, environmental and economic considerations. The object of this work is to obtain a calcium silicate material for the needs of the construction. The purpose is limited to development of appropri...
Article
Full-text available
Preparation and synthesis of gold nanoparticles with small size and suitable stability is very important and applicable particularly in engineering, medicine and biology. In this study gold nanoparticles were synthesized by a reduction of tetrachloroaurate ions (AuCl 4-) in aqueous medium using sodium citrate. The size and shape of gold nanoparticl...
Article
Full-text available
The aim of the present paper is to select suitable filtering material which would be effective for the separation of the aqueous petroleum emulsion. Furthermore, the paper discusses the principles and conditions for separation using filtering materials of different natures. During the experiments, the influences of several factors on the degree of...
Article
Full-text available
Article
Full-text available
The purpose of this study is to present one of the possible methods for assessing the roughness of ceramics surface based on its digital image. A porous ceramic materials for filtration purpose having open porosities up to 65.84 % are synthesized. X-ray analysis carried out shows that the ceramics main phases refer to corundum, gelenite and calcium...
Article
Full-text available
Porous ceramics were synthesized with open porosities of up to 65.84 %. The porosity was achieved mainly by thermal dissociation of CaCO 3 and graphite burning. The main phases observed in the compositions of the highest porosity were as follows: corundum, gelenite and calcium-aluminate. The values of the coefficient of fractal dimension (D) of the...
Article
Full-text available
Zinc silicate α-willemite (Zn 2 SiO 4) is an orthosilicate with rhombohedral symmetry. Cobalt doped willemite is a pigment with application in high-temperature ceramics and glaze production. A full series of cobalt containing wil-lemite ceramic pigments with composition xCoO. (2-x)ZnO. SiO 2 , where x = 0.125, 0.250, 0.375, 0.50, 0.625, 0,75, 0.875...
Conference Paper
Full-text available
In the paper application of the InterCriteria analysis approach to real dataset with instances of hourly averaged responses from an array of 5 metal oxide chemical sensors embedded in an air quality chemical multisensor device [29, 30] is represented. The InterCriteria analysis is a new method that can be used for multicriteria decision making. The...
Article
Full-text available
In the paper application of the InterCriteria analysis approach to real dataset with instances of hourly averaged responses from an array of 5 metal oxide chemical sensors embedded in an air quality chemical multisensor device [29, 30] is represented. The InterCriteria analysis is a new method that can be used for multicriteria decision making. The...
Article
Full-text available
The order of selective adsorption of seven of the most widely distributed heavy metal ions in waste waters by natural clinoptilolite and synthetic one of type L was studied. The studied ions were iron, zinc, manganese, lead, cadmium, copper and nickel. The study was aimed to determine the possibility for efficient practical application of the two z...
Conference Paper
Full-text available
Article
Full-text available
In this study the adsorption of Cu (II) ions from aqueous solutions on synthetic zeolite NaA was evaluated. The effect of solution temperature and the determination of the kinetic parameters of adsorption of Cu(II) from aqueous solution on zeolite NaA is important in understanding the adsorption mechanism. Variables of the system include adsorption...