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Preparation and characterization of chrome doped sphene pigments prepared via precursor mechanochemical activation
No full textMechanical activation of precursors has been used for the preparation of Cr-doped sphene ceramic pigments (CaTi1-yCrySiO5). Ceramic material has been prepared from a powder mixture of CaCO3, TiO2, SiO2 and Cr(NO3)center dot 9H(2)O using vibro-milling for homogenization and activation of precursors. The mechanochemical process initially yielded amorphous powders, which on further calcination, crystallized to yield Cr-doped sphene ceramic pigment. Phase evolution in CaTi1-yCrySiO5 composition with thermal treatment was investigated by X-ray powder diffraction (XRPD). Texture properties and particle size distribution were analyzed by scanning electron microscopy (SEM) and laser diffraction, respectively. UV/Vis reflectance spectra are used to determinate the behavior of the chromium ion. The color efficiency of pigments was evaluated by colorimetric analysis (CIE L * a * b system). Photoluminescence measurements were also performed
Biomass as a significant source of energy in the municipality of Majdanpek
No full textBiomasa, kao obnovljivi izvor energije, može se konvertovati u energiju na tri načina: termalnom konverzijom, hemijskom konverzijom i biohemijskom konverzijom. U ovom radu se razmatra konverzija biomase koja potiče od šumskih resursa, odnosno od drvnih peleta. Rezultati pokazuju da ovaj način konverzije energije može biti značajan izvor termalne energije, posebno u oblastima bogatim šumama, kao što je na primer područje Opštine Majdanpek. Toplota proizvedena iz drvnih peleta mogla bi čak da zameni konvencionalni proces dobijanja toplote zasnovan na sagorevanju goriva kao što je, na primer, ugalj.Biomass, as a renewable energy source, can be converted to energy in three ways: thermal conversion, chemical conversion and biochemical conversion. In this paper, we consider conversion of biomass that originates from forest resources - wood pellets. The results have shown that this type of energy conversion can be a significant source of the thermal energy, especially in areas rich in forests, such as the municipality of Majdanpek. Heat produced from the wood pellets could even replace a conventional process of heat production based on the combustion of fuels such as, for instance, coal
In vitro and in vivo efficacy of a hydrated sodium calcium aluminosilicate to bind and reduce aflatoxin residues in tissues of broiler chicks fed aflatoxin B-1
No full textThe aim of this study was to determine the binding capacity of a hydrated sodium calcium aluminosilicate (HSCAS) for aflatoxin B-1 (AFB(1)), and the efficacy of the HSCAS to reduce the concentrations of residual AFB(1) and its metabolites in the liver and kidney of broilers fed AFB(1). One hundred 1-d-old male broilers (Ross 708) were maintained in chick batteries and allowed ad libitum access to feed and water. A completely randomized design was used with 5 replicate pens of 5 chicks assigned to each of 4 dietary treatments from hatch to 21 d. Dietary treatments included the following: A) basal diet (BD), with no HSCAS or AFB(1), B) BD supplemented with 0.5% HSCAS only, C) BD supplemented with 2.5 mg of AFB(1)/kg of feed, and D) BD supplemented with 2.5 mg of AFB(1)/kg of feed and 0.5% HSCAS. On d 21, 5 chicks from each treatment were anesthetized with carbon dioxide, killed by cervical dislocation, and samples of liver and kidney were collected for analysis of AFB(1) residues. The percentage of AFB(1) bound for each concentration of adsorbent (100, 10, 1, 0.5, 0.25, and 0.05 mg/10 mL) was 100, 91.1, 81.8, 75.4, 40.1, and 8.8%, respectively. Concentrations of aflatoxin residues (AFB(1), aflatoxicol, aflatoxins B-2 and G(1)) were lower (P LT 0.05) in livers and kidneys of birds fed AFB(1) plus HSCAS (diet D), when compared with birds fed AFB(1) alone (diet C). However, histopathology data from the in vivo study indicated that HSCAS did not prevent lesions associated with aflatoxicosis. The decrease in the bioavailability of AFB(1) caused by the HSCAS reduced aflatoxin residues in liver and kidney, but not enough to completely prevent the toxic effects of AFB(1) in broilers
Sulfate content in atmospheric precipitation in unsettled region Kamenicki Vis
No full textSvakako jedan od još uvek aktuelnih problema u svetu, koji se javlja kao posledica prekomernog zagađivanja životne sredine, je i pojava kiselih kiša. Prekomerne emisije kiselih oksida iz procesa sagorevanja fosilnih goriva i metalske industrije, kao što su SO2 i NOx, su jedni od glavnih uzročnika ove pojave. U cilju da se skrene pažnja na ovaj još uvek aktuelan problem, i sagleda trenutno stanje, analizirana je promena sadržaja sulfata u atmosferskim padavinama u nenaseljenoj, ruralnoj oblasti u toku višegodišnjeg perioda. U ovom radu dat je pregled rezultata praćenja sadržaja sulfata u atmosferskim padavinama uzorkovanim na GAW/EMEP stanici 'Kamenički Vis'. Pregledom je obuhvaćen period od 2000. do 2010. godine, a prikazane su srednje godišnje vrednosti koncentracija sulfata u padavinama. Dobijeni podaci su prodiskutovani u svetlu prosečnog sadržaja sulfata u padavinama u Evropi, prekograničnog doprinosa i ukupnih nacionalnih emisija sumpornih oksida u Evropi i Srbiji.Acid rain is still one of the important and current issues arising from excessive anthropogenic pollution of the environment. Excessive emissions of acidic oxides, such as SO2 and NOx, coming from industrial combustion processes and metal industry are one of the main causes of this phenomenon. In order to highlight this issue and reflect on current status, annual change of sulfate content in atmospheric precipitation collected over ten year period in rural, unsettled area was analyzed. In this paper an overview of data collected during monitoring of sulfate content in atmospheric precipitation on GAW/EMEP station Kamenicki Vis is given. Ten year period, from 2000 to 2010, is covered and annual arithmetic mean sulfate concentrations are presented. Obtained data is also discussed in scope of European average levels of sulfate content in precipitation, trans-boundary deposition and total national emissions of sulfur oxides in Europe and Serbia
Quality of zeolit from Vranjska banja deposit according to size classes
No full textObavljena su ispitivanja kvaliteta polaznog uzorka i kvaliteta pojedinih klasa krupnoće na uzorku prirodnog zeolita iz ležišta Zlatokop (okolina Vranjske Banje, Srbija). Cilj ispitivanja je bio da se utvrdi homogenost kvaliteta zeolita u pogledu klasa krupnoće i da li se odvajanjem neke klase lošijeg kvaliteta može izdvojiti klasa sa višim sadržajem osnovnog minerala - klinoptilolita. Karakterizacija polaznog zeolita, kao i određenih klasa krupnoće je urađena određivanjem hemijskog sastava, sadržaja oksida CaO+MgO+Na2O+K2O kao i kapaciteta katjonske izmene (KKI) kao i korišćenjem XRD analize. Dobijeni rezultati su ukazali da sve analizirane klase krupnoće (-2+0,8; -0,8+0,6; -0,6+0,4; -0,4+0,1; -0,1+0; -0,3+0,63; -0,63+0 i -0,43+0 mm) imaju dobar kvalitet. Najveće vrednosti kapaciteta katjonske izmene (KKI) imaju klase -0,043+0mm (166,5 meq/100 g) i -0,063+0 mm (158,8 meq/100 g). Rezultati su ukazali da nešto bolji kvalitet zeolita se može postići kada se ove klase izdvajaju prosejavanjem iz polaznog uzorka nego kada se iste dobiju mlevenjem polaznog uzorka na tu finoću.This paper presents the results of investigations of the quality of the natural zeolite as well as the quality of specific particle size classes of the natural zeolite. The aim of the investigations was to determine if the different classes possess different qualities. The starting material used in experiments was the natural zeolite from the Zlatokop deposit (Vranjska Banja, Serbia). The classes -0.2+0.8 mm; -0.8+0.6 mm; -0.6+0.4 mm; -0.4+0.1 mm were obtained by wet sieving of the natural zeolite. Grinding processes of the natural zeolite gave classes -0.3+0.63 mm; -0.63+0 mm; -0,43+0 mm. Chemical composition, mineralogical XRPD and cation exchange capacities (CEC) were analyzed for the starting sample and the obtained particle size classes. It was determined that all particle size classes possess similar qualities. The highest cation exchange capacity was observed in classes -0.043+0 mm (166.5 meq/100 g) and -0.063+0 mm (158.8 meq/100 g)
Preparation of glass-ceramic in Li2O-Al2O3-GeO2-P2O5 system
No full textThe results of preparation and structural characterization of glass-ceramics from the system Li2O-Al2O3-GeO2-P2O5 are shown in this paper. The crystallization behaviour of the selected glass was examined under non-isothermal and isothermal crystallization conditions. DTA, XRD and SEM methods were employed for analyses. It was confirmed that this glass crystallizes by the volume crystallization mechanism. The results also showed that the glass crystallize by primary crystallization. As a primary phase the LiGe2(PO4)3 is formed and the traces of GeO2 as a secondary one is present. The crystallization process occurred at a high homogeneous nucleation rate and the spherical morphology of crystal growth. By applying the Kissinger relation the activation energy of crystal growth Ea = 462 kJ/mol was determined
Procedures for processing of copper secondary raw materials
No full textTehnološki postupci prerade sekundarnih sirovina bakra uključuju dva osnovna stupnja: pripremu bakarnih otpadaka i njihovu dalju metaluršku preradu. Za pripremu bakarnih otpadaka koriste se različiti postupci u zavisnosti od vrste i kvaliteta sekundarne sirovine. Priprema bakarnih provodnika obuhvata rezanje, drobljenje, vazdušnu separaciju i prosejavanje sa ciljem odvajanja bakra od izolacije. Masingana šljaka se melje, a potom odvaja metalna od oksidne faze. Pripreme strugotine uključuje sortiranje, prosejavanje, odmašćivanje, magnetnu separaciju i briketiranje. Proces pripreme elektronskog otpada je složeniji i sastoji se od drobljenja, soriranja, magnetne separacije, kalcinacije, sagorevanja, usitnjavanja i uzorkovanja. Sve operacije pripreme utiču na kvalitet metalurške prerade, odnosno na kvalitet proizvoda.The technological procedures for copper secondary raw materials processing include two basic stages: pretreatment of the copper waste and its further metallurgical processing. For copper waste pretreatment technology, there are different applied procedures depending on the type of raw material. Scrap of copper cables and wires preparation includes cutting, crushing, air separation and sieving; with the aim of separating the copper from the electrical insulation. The brass slag is grinded, followed by separation metal from oxide components. Chips preparation includes sorting, sieving, degreasing, magnetic separation, and briquetting. The process of electronic scrap preparing is more complex and consists of crushing, sorting, magnetic separation, calcination, combustion, shredding, and sampling. All operations of pretreatment are influencing the quality of metallurgical processing
Potentiostatic oxidation of AgCu50 alloy in alkaline solution in the presence of chlorides
No full textSEM and EDS analyses of AgCu50 alloy were performed after potentiostatic oxidation in an alkaline solution in the presence or absence of chloride ions. Oxidation in pure alkaline solution was favoured on the portion where a eutectic mixture was present on the surface. There was an essential difference between SEM images obtained in pure alkaline solution and in the presence of chloride, when voluminous deposits covering the whole eutectic area and expanding towards the middle of primary crystals appeared. EDS analysis confirmed that both oxides and chlorides of silver form in parallel. Chlorides disturb the protective performance of copper oxides
Kinetic investigation of silver sulfide phase transformations
No full textThe results of kinetic investigation of silver sulfide (Ag2S) phase transformations-monoclinic (alpha) to body-centered-cubic (beta) and body-centered-cubic to face-centered-cubic (gamma) crystal form - are presented in this paper. Measured data obtained by thermal analysis under non-isothermal conditions were used for kinetic analysis. The activation energy for investigated phase transformation process was determined according to the methods by Kissinger and Ozawa
In vitro evaluation of the efficacy of peach stones as mycotoxin binders
No full textRad opisuje in vitro model za procenu sposobnosti koštice breskve (nemodifikovane i modifikovane), pripremljene u Institutu za tehnologiju nuklearnih i drugih mineralnih sirovina u Beogradu, da adsorbuje različite mikotoksine. Koštice breskve su nabavljene od 'Vino Župe' iz Aleksandrovca, kompanije gde su odložene kao otpadni materijal njihove Fabrike sokova. Nakon odgovarajuće pripreme, u ispitivanju su korišćene dve vrste čestica koštice breskve: jedna nemodifikovana (PS) i druga dobijena kiselinskom modifikacijom (MPS). In vitro metodom je testirana adsorpcija šest mikotoksina: aflatoksina B1 (AFL), ohratoksina A (OTA), deoksinivalenola (DON), zearalenona (ZON), di-acetokiscirpenola (DAS) i T-2 toksina. Za eksperimenate adsorpcije korišćeni su sirovi ekstrakti mikotoksina proizvedeni u Odeljenju za mikrobiologiju Bio-ekološkog centra u Zrenjaninu. Sposobnost čestica nemodifikovane i modifikovane koštice breskve za vezivanje mikotoksina je ocenjivana u elektrolitu 0,1 M K2HPO4 čija je pH vrednost podešena na 3,0 odnosno 7,0. Maseni odnos pojedinačnih mikotoksina i uzoraka koštice breskve je bio 1:5000. Eksperimentalne smeše su inkubirane 1 sat na rotacionoj tresilici (185 o/min) na sobnoj temperaturi (22-25ºC). Posle inkubacije, ekstrakcija neadsorbovanih mikotoksina iz filtrata eksperimentalnih smeša su izvršene organskim rastvaračima, a njihova kvantifikacija metodom tankoslojne hromatografije.The paper describes in vitro model for the evaluation of ability of peach shell (unmodified and modified), prepared at the Institute for Technology of Nuclear and Other Mineral Raw Materials, Belgrade, to adsorb different mycotoxins. Peach stones were obtained from 'Vino Župa' Company from Aleksandrovac, where they have been disposed of as by-products from their Juice Factory. After proper preparation, two sorts of peach shell particles were used: one as unmodified peach shell particles (PS) and another one obtained by acid modification, denoted as MPS. Adsorption of six mycotoxins: aflatoxin B1 (AFL), ochratoxin A (OTA), deoxynivalenol (DON), zearalenone (ZON), diacetoxyscirpenol (DAS) and T-2 toxin by PS and MPS was tested in vitro. Crude extracts of mycotoxins, produced at the Department of Microbiology of Bio-ecological Center, Zrenjanin, were used for adsorption experiments. The ability of binding mycotoxins was evaluated in the electrolyte 0.1 M K2HPO4, which pH value was adjusted to 3.0 and 7.0, respectively. Mass ratio of individual mycotoxin and peach shell samples was 1:5000. The experimental mixtures were incubated for 1 hour on a rotary shaker (185 rpm) at room temperature (22-25ºC). After incubation, the extractions of non-adsorbed mycotoxins from the filtrates were performed with organic solvents, and their quantification was done by thin-layer chromatography (TLC)