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Forecast resources of zeolithic tuffs of Serbia
No full textOur zeolite tuff deposits (Zlatokop, Igroš, Jablanica 1, Beočin, Toponica and Slanci), which were the subject of detailed research, spatially and genetically are connected to volcanic volcaniclastic rocks of marine environment of Senonian and Neogene age, as well as lake sediments of Neogene age. Zeolitic tuff deposits were formed as a product of devitrification of volcanic glass. More will be said here about the prognostic resources of our zeolite tuffs, both in relation to the registered phenomena so far, and to possible areas in terms of finding new quantities of this economically very interesting mineral raw material
Ochratoxin A and zearalenone adsorption by surfactant modified zeolite
No full textCetylpyridinium chloride (CP) was used to modify the surface of the natural zeolite and adsorption
of two mycotoxins, ochratoxin A (OCHRA) and zearalenone (ZEN) was investigated. The
organozeolites were prepared with three different levels of CP (20, 50 and 100% of zeolite’s external
cation exchange capacity) and mycotoxin adsorption experiments were done at pH 3 and 7. Results
showed that with increasing amounts of CP at the zeolitic surface, adsorption of OCHRA and ZEN
increased, as well as with increasing amounts of solid phase in suspension. Adsorption of OCHRA
was dependent of the form of OCHRA in solution while ZEN adsorption was pH independent.
Maximum adsorption was obtained with the highest level of CP present at the zeolitic surface for
both mycotoxins
Hydrothermal synthesis of hydroxyapatite on calcium-enriched natural and synthetic zeolite as a carrier
No full textThe aim of this study was to investigate the possibilities and to optimize the conditions for the synthesis of hydroxyapatite (HAP) on calcium-enriched natural and synthetic zeolites as carriers. Two synthetic zeolites were used in the paper: zeolite 4A (Na-form) and zeolite 5A (Ca-form) as well as natural zeolite - clinoptilolite from Slanci deposit in Serbia.
Clinoptilolite and zeolite 4A were enriched with calcium ions by ion exchange treatmentin order to enable the source of Ca2+in the crystallization of hydroxyapatite. Phosphorus, necessary for the crystallization of hydroxyapatite, was introduced through a solution of ammonium-hydrogenphosphate. The influence of the concentration of hydrogen phosphate ions, temperature and crystallization time of hydroxyapatite on the morphology of the zeolite surface as well as the degree of its coverage with newly formed hydroxyapatite particles was monitored in the experiments. The obtained powders were characterized by X-ray powder diffraction (XRD), thermal TG-DTG analysis, infrared spectroscopy with Fourier transformation (FTIR) and scanning electron microscopy (SEM). Based on the structural analysis, it was shown that the synthesis of hydroxyapatite did not affect on the structure of the zeolite, except in the case when a very concentrated hydrogen-phosphate solution was used. Thermal analysis showed that all obtained zeolite and HAP samples were stable up to 800 °C. Optimization of the hydrothermal crystallization process showed that temperature and time do not have a crucial influence on the synthesis of the materials (similar results were obtained at 120 °C for 20 hours and at 160 °C for 4 hours). When the concentration of the solution of ammonium hydrogen phosphate was higher, larger crystals of hydroxyapatite were obtained, but the crystal lattice of the zeolite was collapsed. SEM micrography showed that unevenly distributed hydroxyapatite crystals were formed on natural zeolite due to the presence of various impurities, while the best results were achieved using zeolite 5A, where
the surface of the zeolite is completely covered with crystals of hydroxyapatite
Composites of phillipsite-rich tuff and surfactant – their characterization and stability
No full textIn this work phillipsite-rich tuff (P) was modified by using amounts of cetylpyridinium
chloride (C) equivalent to 70% and 140% of the zeolite external cation exchange capacity
(ECEC). Accordingly, composites were denoted as PC-70 and PC-140. Prepared composites
were characterized by ATR-FTIR spectroscopy. Additionally, to test the stability of surfactant
molecules attached to the tuff surface, composites were extensively washed with distilled
water, and zeta potential of unwashed and washed samples was measured. FTIR spectra
confirmed presence of C in both composites. Zeta potential measurements showed that
composite containing surfactant in the amount below the ECEC value (PC-70) has much
higher stability and thus is a more appropriate adsorbent for potential practical application for
removal of different pollutants
Modifikovani sintetski zeolit - mordenit kao adsorbens Cu 2+ i Pb 2+ jona iz vodenih rastvora
No full textU ovom radu proučavana je primena adsorbenasa na bazi modifikovanog
sintetskog zeolita - mordenita za uklanjanje jona Cu 2+ i Pb 2+ iz vodenih rastvora. U
cilju poboljšavanja njegovih adsorpcionih svojstava zeolit je modifikovan
korišćenjem (3-aminopropil)trietoksisilana. Preliminarni rezultati pokazali su da
modifikovani mordenit postiže adsorpcioni kapacitet od 21,0 i 63,2 mg/g za Cu 2+ i
Pb 2+ , redom. Adsorpcija oba jona prati kinetiku modela pseudo-drugog reda. Ovaj
model podrazumeva hemijsku interakciju između jona metala i funkcionalnih
grupa na površini silanizovanog mordenita. Dobijeni rezultati ukazuju da je
mordenit modifikovan silanima pogodan adsorbens za potencijalno uklanjanje
jona teških metala iz otpadnih voda
Comparative analysis of Pb(ii) removal kinetics by Immobilized biowaste materials
No full textGrowing industrial activities generate huge amounts of waste biomass worldwide annually, which are, most often, improperly disposed, representing resource lost and secondary pollution sources. Many recent investigations have shown that this kind of biomass material can be reused as high quality sorbent, with certain modifications which would improve separation process. Having this in mind, we have investigated application of two biowaste materials-lignocellulosic waste of peach stones (Prunus Persica L) – IPS and invasive aquatic weed (Myriophyllum spicatum) - MsA, both immobilized in sodium alginate, as lead sorbents. For kinetic investigations, both sorbents were used to remove Pb2+ ions from synthetic solutions (batch reaction system with stirring), under defined operational parameters. Obtained data were modelled using nonlinear form of three most common kinetic models
Superabsorbents based on polymer networks and gels with the addition of nanoparticles for metal wastewater treatment
No full textU ovom radu biće prikazano dobijanje različitih adsorbenata na bazi polimernih mreža i gelova sa dodatkom nanočestica i njihova primena za prečišćavanje otpadnih voda od metala. Polimerne mreže i hidrogelovi kao adsorbenti predstavljaju novu alternativu za sistem tretmana otpadnih voda, ako se uzme u obzir da se mogu lako sintetisati sa željenim osobinama, i to od dostupnih i jeftinih sirovina. Dodatkom nanočestica u takvu polimernu
matricu nastaju nove klase multifunkcionalnih nanokompozitnih materijala, koji vrlo efikasno uklanjaju teške metale, radioaktivne elemente, boje, fenole i pesticide. U poređenju sa konvencionalnim adsorbentima, ovakvi superabsorbenti imaju niz prednosti kao što su visoki adsorpcioni kapacitet, velika brzina adsorpcije, mogućnost primene u širokom opsegu pH vrednosti, a potom i mogućnost desorpcije i ponovne upotrebe.In this paper, the preparation of various adsorbents based on polymer networks
and gels with the addition of nanoparticles and their application for metal wastewater tre atment will be shown. Polymer networks and hydrogels as adsorbents represent a new alte rnative to the wastewater treatment system, given that they can be easily synthesized with thedesired properties, from available and inexpensive raw materials. The addition of nano particles to such a polymer matrix creates new classes of multifunctional nanocomposite
materials, which very efficiently remove heavy metals, radioactive elements, dyes, phenols and pesticides. Compared to conventional adsorbents, such superabsorbents have a number of advantages such as high adsorption capacity, high adsorption rate, the possibility of application in a wide range of pH values, and then the possibility of desorption and reuse
Extraction of ammonium nickel sulfate hexahydrate by hydrometallurgical process from the hyperaccumulating plant Odontarrhena muralis - case study from Serbia
No full textPhytomining is a new promising technique that is based on using hyperaccumulating plants which biomass is utilized as a bio-ore for metal extraction. The Ni-hyperaccumulating species Odontarrhena muralis is widely distributed on ultramafic soils in Serbia, and could be a promising candidate for Ni agromining. In the present study, efficiency of a hydrometallurgical process for Ni recovery using biomass of O. muralis wild population through the synthesis of Ni salts from plant ash in the form of ammonium nickel sulfate hexahydrate, Ni(NH4)(2)(SO4)(2) 6H(2)O-(ANSH) was assessed. The average Ni content in the plant from ultramafic sites in West Serbia was up to 3.300 g kg(-1). The mass yield of ANSH crystals from the crude ash was similar to 12 % with the average purity of 73 % were obtained. By optimizing the purification process before precipitation of ANSH crystals, it is possible to obtain salt crystals of higher purity, which increases the economic profitability of this process. The results of this preliminary study on wild population of O. muralis show the increased potential for implementation of phytomining practices as an alternative way of Ni extraction on ultramafic sites in Serbia
Effect of Delamination on Physico-Chemical Properties of Kaolin
No full textTo provide the quality required for its use, raw kaolin must be subjected to certain processing procedures like delamination which is applied to the layered structure materials. The aim of this research is to determine the possibility of performing delamination in the extruder and to estimate the effects of this process on the physico-chemical properties of kaolin. The results showed that delamination can be efficiently realized in the extruder by shearing densely packed layers under the influence of friction force and added Na2CO3 electrolyte. The crystal structure of the system was thus disrupted. This was confirmed by the Hinckley index (HI) decrease and by the dilatometric characteristics changes during heating. The particle size was reduced and, furthermore, new adsorption centers were formed, which led to an increase in the total cation exchange capacity (CEC). The plasticity of kaolin decreased with the increasing delamination degree, as well as the amount of water required for plastic processing, which is favorable in drying ceramic products
Influence of Pr3+ and CO32- Ions Coupled Substitution on Structural, Optical and Antibacterial Properties of Fluorapatite Nanopowders Obtained by Precipitation
No full textCoupled substitution of fluorapatite (FAP) crystal lattice plays an important role in the engineering of optically active nanomaterials. Uniform fluorapatite nanopowders doped with praseodymium (Pr3+) and carbonate (CO32-) ions have been successfully synthesized by precipitation method under room temperature (25 degrees C). The structural, morphological, chemical and optical properties of monophase material were characterized by X-ray diffraction (XRD), Fourier Transform Infrared and Far Infrared Spectroscopy (FTIR and FIR, respectively), Scanning Electron Microscopy with Energy Dispersive Spectroscopy (SEM/EDS), Transmission Electron Microscopy (TEM) and Photoluminescence Spectroscopy (PL). Coupled substitution of FAP crystal lattice with Pr3+ and CO32- reduces the crystallite size with a constant c/a ratio of 1.72. FTIR study showed that synthesized nanopowders were AB-type CO32- substitution, and FIR study revealed new Pr-O vibrations. TEM analysis was found that synthesized nanopowders were composed of irregular spheres in the nanometer range. The fluorescence of FAP nanoparticles was in the violet-blue region of the visible part of the spectrum. When Pr3+ was doped in a lattice, the violet-blue emission becomes sharper due to reabsorption. MCR-ALS analyses of fluorescence spectra indicated the shift of the maximum to the blue color with the increase in the concentration of Pr3+ ions. Additionally, luminescent nanopowders demonstrated significant antibacterial activity against Escherichia coli. As the obtained nanoparticles showed a good absorption of ultraviolet A light and reabsorption of blue-green luminescence, they are suitable for further development of optically active nanomaterials for light filtering. Optically active PrCFAP nanopowders with antibacterial properties may be promising additives for the development of multifunctional cosmetic and health care products