Maja Kokunešoski

Vinča Institute of Nuclear Sciences | VIN · Department of Physical Chemistry

Porous silica ceramics were obtained at low forming pressure and low sintering temperature by using diatomaceous earth as a silica source and boric acid as an inexpensive additive. The starting raw material, diatomite from surface coal mine Kolubara, Serbia, was purified from organic and inorganic impurities by using heat and chemical treatment. Bo...

Intention of this work was to obtain porous silicon dioxide ceramics by using boric acid as an inexpensive additive at low forming pressure and low sintering temperature. Starting raw material, smectite clay from surface coal mine Kolubara, Serbia, was purified from organic and inorganic impurities by using heat and chemical treatment. Boric acid w...

Ordered mesoporous silica SBA-15 materials were synthesized using Pluronic P123 (non-ionic triblock copolymer, EO20PO70O20) as a template, under acidic conditions and different heating temperatures and time of the reaction solution. These materials were characterized by nitrogen adsorption–desorption measurements, Fourier-transformed infrared spect...

Porous silica ceramics were obtained at low forming pressure (40–80 MPa) and low sintering temperature (850–1300 °C) for 4 h in air. Boric acid was used as a low-cost additive, in the amount of 2 wt%. Relatively high porosities of nearly 40 and 65% are obtained for the samples of clay and diatomite pressed at 40 MPa, and sintered at 1000 °C, respec...

Influence of iron on the crystallization mechanism of mullite obtained from the hybrid gels and doped with different concentrations of iron was examined. DTA analysis showed that iron addition had a beneficial effect on the mullite formation leading to the temperature decreasing as the amount of iron increased. X-ray diffraction and M?ssbauer spect...

In this paper, the effects of the addition of silicon nitride seeds on the phase composition, particle size, and shape of silicon nitride powders obtained by carbothermal reduction-nitridation were studied. Environmentally friendly natural raw material, diatomaceous earth, was used as a Si precursor. Three different carbon sources were used: activa...

Effect of methyl methacrylate (MMA) as a binder and heating treatment were investigated to improve green alumina compacts machinability. Properties of green compacts and their corresponding sintered samples prepared with and without MMA were compared. Investigation of green and sintered properties was performed on samples compacted at applied press...

In present study FeAl-LDH@SiO2 adsorbent was used for phosphate and arsenate removal from aqueous solutions. Silica, obtained from rice husks, was used as a substrate for the deposition of FeAl based layered double hydroxides (FeAl-LDH) particles. Synthesis of FeAl-LDH, obtained at Fe/Al molar ratio of 3:1, was performed via co-precipitation and co...

The textile industry is one of the largest water-consuming industries in the world. The wastewater generated by the textile industry is a major source of pollution, containing mostly dyes, but also detergents, and heavy metals. Since dyes can have a negative impact on the environment, human and aquatic life, it is really important to find proper so...

Diatomite (diatomaceous earth) and clay minerals deposits from the mining basin Kolubara, Serbia, are natural materials with high economic potential in many fields. As received and treated materials, diatomite and clay were characterized using X-ray diffraction, mercury intrusion porosimetry, particle size distribution, scanning electron microscopy...

The study of an effect of iron doping on the structural, microstructural and mechanical properties of sintered iron-doped mullite is presented. The results of phase composition, performed in detail by Mössbauer spectroscopy and XRD analysis, revealed that all added iron was inside the mullite lattice forming the single phase up to 12% by weight of...

Macroporous silica ceramic was obtained using clay and diatomite. Boric acid as a low-cost additive in the amount of 1 wt% was used. These porous materials were obtained at low forming pressure (40-80 MPa) and lower sintering temperature (850-1300 ºC) for 4h in air. The influence of boric acid, forming pressure, and sintering temperature on the mic...

Co-Mo carbides were prepared by impregnation with aqueous solution of metal salts and sucrose into ordered mesoporous SBA-15 silica template using carbothermal hydrogen reduction. Bimetallic Co-Mo carbide obtained by using carbothermal hydrogen reduction of Co-Mo precursors is formed when the Co-Mo molar ratio is 1.0. The obtained samples were char...

Mesoporous silica SBA-15 materials of high specific surface area (~700 m2 g−1) were synthesized by using block copolymer Pluronic P123 as template and tetraethoxysilane as silica source. The obtained materials were characterized by XRD, nitrogen adsorption - desorption measurements, SEM, EDS and AFM analysis. It was found that small modifications o...

Starting raw materials, clay and diatomite, from coal mine Kolubara, Serbia were purified using heat and chemical treatment. Porous silica ceramics were obtained at low forming pressure (40-80 MPa) and low sintering temperature (1000-1300 ºC) in air. Boric acid as a low-cost additive was used. Sintered samples have average pore size diameters rangi...

Amorphous iron (III) oxide was obtained from clay, using ammonium hydroxide as a precipitating agent. Influence of freeze drying under vacuum, as a drying method, on particle size, chemical composition, and crystallinity of obtained iron (III) oxide powder was investigated. After freeze drying, precipitate was annealed in air at 500 °C and 900 °C....

In this paper we present the results of applying the new approach for calculating coincidence summing effects. The application of analytical approaches to coincidence summing effects makes it possible to predict all summation peaks that occur in the spectrum. Accordingly, based on the value of the peak area in the spectrum and knowledge of probabil...

The kinetics of the oxygen reduction reaction (ORR) greatly influences the performance and the costs of electrodes in fuel cells. Commercial platinum based electrocatalysts exhibit the highest performance, but also increase the cost of the fuel cells. On the other hand, carbon based platinum catalyst support is subject to oxidation, which causes ag...

In this work, the reliability of image analysis for the numerical evaluation of Basic Red 46 (BR 46) dye adsorption process was studied. The image analysis was carried out on dye adsorbed onto SBA-15 mesoporous silica, by use of Image-Pro Plus software. Pixel-specific calibration curves were derived and used to obtain dye concentration from the thr...

In this work, a new method for the quantification of methyl violet cationic dye sorption onto SBA-15 mesoporous silica was developed. This method related the intensity of coloration of SBA-15 samples (after reached equilibrium sorption) within dye concentration in aqueous solution using Image-Pro Plus software. The sorption process of methyl violet...

The most promising method for obtaining a large variety of non-oxide products having important technical uses is carbothermal-reduction reaction (CRR). By using this procedure, SiC and ZrC/SiC powders are obtained from diatomaceous earth and zircon powder. In this way the synthesized powders are obtained at a relatively low temperature due to good...

Diatomite from surface coal mine Kolubara, Serbia, was used as a silica source. Diatomite was purified from organic and inorganic impurities by using heat and chemical treatment. Boric acid was used as binding and sintering aid up to 2 wt%. Powder was compacted by different pressures up to 80 MPa and sintered at diferent temperature from 850, to 13...

The aim of this work was to obtain porous silicon dioxide ceramics by using boric acid as an inexpensive additive at low forming pressure and low sintering temperature. Starting raw materials, clay and diatomaceous earth from surface coal mine Kolubara, Serbia, were purified from organic and inorganic impurities by using heat and chemical treatment...

Lipase from Candida rugosa was immobilised by adsorption onto laboratory prepared supports, silica SBA-15 and zirconia. The adsorption process was studied as a function of pH in terms of percent of adsorbed lipase, enzyme activity and zeta potential of support and enzyme. Several analytical approaches such as laser Doppler electrophoresis, Fourier...

Porous ceramic based on silicon dioxide was prepared using inexpensive method and starting raw materials, diatomaceous earth (surface coal mine Kolubara, Serbia). Boric acid was used as binding and sintering aid. Content of boric acid was varied up to 1 wt%. Diatomite was purified using heat treatment (600 ºC, 2 h) and aqueous solution of HCl (weig...

The new porous carbon materials were obtained by templating procedure using mesoporous silica (SBA-15) as template. The ordered mesoporous silica materials were synthesized by using Pluronic P123 (non-ionic triblock copolymer, EO20PO70O20). SBA-15/cryogel carbon composites were obtained by sol–gel polycondenzation of resorcinol and formaldehyde in...

The ordered mesoporous silica SBA-15 was synthesized and used as a template for obtaining mesoporous carbon replicas. Adsorptive removal of pesticide 2,4-dichlorophenoxyacetic acid (2,4-D) from aqueous solutions onto two carbon replicas was investigated. Batch adsorption experiments varied in initial adsorptive concentration, contacting times, solu...

The ordered mesoporous silica SBA-15 materials were synthesized using Pluronic P123 (non-ionic triblock copolymer, EO20PO70O20), under acidic conditions. SBA-15/carbon cryogel composites were obtained by sol–gel polycondensation of resorcinol and formaldehyde followed by freeze drying, and subsequent pyrolysis, in the presence of different amounts...

Nanometric size (Ba, Yb) doped ceria powders with fluorite-type structure were obtained by applying self-propagating room temperature methods. Tailored composition was: Ce 0.95−x Ba 0.05 Yb x O 2−δ with fixed amount of Ba − 0.05 and varying Yb content "x" from 0.05 to 0.2. Powder properties such as crystallite and particle size and lattice paramete...

A novel method for synthesis of carbon cryogel/zeolite composites was obtained. Method considers forming of carbon cryogel from the sol-gel polycondenzation of resorcinol and formaldehyde, followed by freeze drying, and subsequent pyrolysis in presence of different amount of zeolite. Characterization of composite materials by nitrogen adsorption sh...

SBA-15/carbon cryogel composites were obtained by the sol-gel polycondenzation of resorcinol and formaldehyde, in the presence of different amount of SBA-15, followed by freeze drying, and subsequent pyrolysis. Ordered mesoporous silica SBA-15 materials were synthesized by using Pluronic P123 (non-ionic triblock copolymer, EO20PO70O20) as a templat...

Ordered mesoporous silica SBA-15 materials were synthesized by using Pluronic P123 (non-ionic triblock copolymer, EO20PO70EO20) as a template, under acidic condition. These materials were characterized by nitrogen adsorption-desorption measurements, scanning electron microscopy (SEM), X-ray diffraction (XRD) and thermo-gravimetric analysis (TGA). I...