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Geological characterization of zeolites from “Igros” as raw materials for use in various fields of ecology
No full textDeposit of zeolitic tuff ""Igroš"" near Brus belongs to the village Igroš, which is
administratively located in the area SO Brus and is about 3 km from the main road
Krusevac Brus.
On the part of the field test site in Igroš the ore field ""Igroš Vidojevići"",
there are two ore bodies, ""ore body I"" and ""ore body II ."" In this paper are
given the basic characteristics and presents of the results the latest research zeolitic tuff
from deposits Igroš
The influence of glass composition on the dissolution rate
No full textIn this paper the results of investigation of the polyphosphate glasses dissolution in acid solution at temperatures of 20, 30 and 37 °C were presented. The dissolution process in citric acid is complex and can be explained by hydration reaction and hydrolysis, leading to the disruption of phosphate chains which form the structure of glass. Mechanism of chemical reactivity of polyphosphate glasses, acting as slow release fertilizers in soil solutions was presented. The results of the dissolution experiments indicated that this glass can be used as an eco- fertilizer in soil remediation
Microstructure of different multicomponent shape memory alloys
No full textThe results of microstructure investigation of different ternary and quaternary shape memory alloys are presented in this paper. Investigated alloys belong to the ternary systems Cu-Al-Zn and Cu-Mn-Ni and quaternary system Ni-Cu-Fe-Mn. Testing was carried out using the light optic microscopy (LOM) and scanning electron microscopy with energy dispersive X-ray spectrometry (SEM-EDX)
Synthesis, structural characterisation and antibacterial activity of Ag+-doped fluorapatite nanomaterials prepared by neutralization method
No full textSilver doped fluorapatite nanopowders were synthesised by neutralization method, which consists of dissolving Ag2O in solution of HF and H3PO4 and addition to suspension of Ca(OH)2. The powder XRD, SEM and FTIR studies indicated the formation of a fluorapatite nanomaterials with average length of the particles is about 80 nm and a width of about 15 nm. The FTIR studies show that carbonate content in samples is very small and carbonte ions substitute both phosphate and hydroxyl groups in the crystal structure of samples, forming AB-type fluorapatite. Antibacterial studies have demonstrated that all Ag+-doped fluorapatite samples exhibit bactericidal effect against pathogens: Staphylococcus aureus, Micrococcus luteus and Kllebsiela pneumoniae. Antibacterial activity increased with the increase of Ag+ in the samples. The atomic force microscopy studies revealed extensive damage to the bacterial cell envelops in the presence of Ag+-doped fluorapatite particles which may lead to their death. The synthesized Ag+-doped fluorapatite nanomaterials are promising as antibacterial biomaterials in orthopedics and dentistry
Mechanical properties of limestone briquettes and pellets with bentonite for calcification of acid soil
No full textIn this paper are presented results obtained in investigation of the mechanical properties of limestone briquettes and pellets, with bentonite as binding agent, for calcification of acid soil. The investigated limestone was limestone dust from “Dobrilovića Brdo’’ deposits grinding plant, obtained from briquetting process in a laboratory roll briquette press (produced by Komarek, model B05), and pelletizing process in a laboratory pelletizing plate (produced by Eirich, model TR-04). Various mass fractions of bentonite as binding agent for limestone were used, while other parameters were constant for all samples. We investigated impact resistance of the obtained briquettes and pellets. Results of these investigations imply that mechanical properties of the investigated briquettes are not significantly improved when more than 5% of bentonite as binding agent is used, while the mechanical properties of the investigated pellets are significantly better when more then 5% of bentonite as binding agent is used, but in comparison with briquettes mechanical properties, pellets are much too poorer
Investigation of the application of the natural and with lead ions contaminated zeolite as an addition in portland cement
No full textIn presented paper results of the removal of lead ions from water solutions by the natural zeolite (clinoptilllite) and application of such contaminated zeolite materials as a supplement for standard additions portland cement are showed. In this investigations, the natural zeolite (clinoptilollite) with particle size 100% 43 μm was used. The experiments of lead ions adsorption showed that the maximum adsorption capacity of the natural zeolite was 66 mg Pb 2+ /g. After adsorption experiments the saturated zeolite with lead ions was used as a supplement to portland cement. Investigations of the mechanical properties of the cement with the addition, natural zeolite and zeolite saturated with lead ions showed that this material can be used as a supplement for portland cement up to 30%
Removal of lead ions from simulated and real pollutant solutions by using the natural and Fe(III)-modified zeolite
No full textThe efficiency of the natural and Fe(III)-modified zeolite for Pb2+ removal at different initial
pH (2.5, 4.2 and 5.0) was investigated. For initial pH 2.5, for all concentrations and both
adsorbents ion exchange of inorganic cations in zeolites with lead ions, together with uptake of
hydrogen occurred. For initial pH 5.0 it was determined that at lower initial concentrations of
lead ion, ion exchange occurred, while at higher initial concentrations beside these processes,
chemisorption of lead ions occurred on both adsorbents. Preliminary experiments on waste
water obtained after flotation process in facility of lead and zinc mine showed that waste water
treatment with both adsorbents reduced the content of all investigated heavy metal cations.
However, better removal was achieved with the Fe(III)-modified zeolite
Co-Mo-Cr alloys for dentistry obtained by vacuum precise casting
No full textZa proizvodnju odlivaka od kojih se izrađuju zubni implantati, ortodontski aparati i pomoćni materijali koristi se više legura Co-Cr-Mo, različitog sastava. Ovde je reč o leguri, koja pored odsustva nikla, svoje biokompatibilnosti i otpornosti na koroziju, ima odlične mehaničke karakteristike, kao što su tvrdoća, zatezna čvrstoća i žilavost. Predstavljena je tehnologija pripreme sirovina, kao i izrada same legure u vidu uzoraka-tabletica od kojih se izradjuju zubni implantati, tehnologijom preciznog livenja u vakuumu, korišćenjem metode topivih modela. Osim eksperimantalnih parametara, praćen je hemijski sastav od polaznih sirovina do gotove legure. Prikazana je mikrostruktura uzoraka u livenom stanju.There are several biocompatible Co-Cr-Mo alloy compositions, as well as technological processes suitable for obtaining the tablet samples aimed to produce dental implants and orthodontic devices. Here presented Co-Cr-Mo alloy, besides its biocompatibility, corrosion resistance, and nickel absence, is favorable for its mechanical properties, such as hardness, tensile and fatigue strength. The technology for raw materials preparation and manufacturing of a Co-Cr-Mo alloy for dental implants vacuum precise casting is presented here. Besides the technological process characteristics, there are the chemical analysis of raw materials, alloy obtaining guidelines and microstructure of as-cast samples
In vitro evaluation of the ability of beer fermentation residue containing Saccharomyces cerevisiae to bind mycotoxins
No full textIn vitro tests were performed to determine the ability of beer fermentation residue (BFR) containing Saccharomyces cerevisiae to bind aflatoxin B-1 (AFB(1)), zearalenone (ZEA), ochratoxin A (OTA) and deoxynivalenol (DON). BFR was obtained from a microbrewery, dried and ground, resulting in approximately 1.0 x 10(10) S. cerevisiae cells g(-1) BFR. Binding assays consisted of suspending BFR (100 mg) in 10 mL of buffer solution (pH 3.0 or 6.5) spiked with AFB(1), ZEA, OTA or DON (2.0 mu g ml(-1) of each mycotoxin), incubation (60 min, 25 degrees C) followed by centrifugation. The supernatants were analyzed by high performance liquid chromatography. BFR had higher binding capacity for ZEA (75.1% and 77.5% at pH 3.0 and 6.5, respectively), when compared with AFB(1), OTA and DON (less than 60% and 40% at pH 3.0 and 6.5, respectively). BFR also produced linear isotherms for ZEA at both pH values, hence indicating a potential application of industrial fermentation by-products containing yeast cells in reducing the bioavailability of ZEA in contaminated feedstuffs. However, in vivo studies are required to prove its efficacy in livestock and poultry
Can the origin of some metals in the seagrass Posidonia oceanica be determined by the indexes of metals pollutions?
No full textTo assess metal pollution, Fe, Mn, Cu, Zn, Pb, Ni, Co, As, Cd, and Hg contents in samples of the seagrass Posidonia oceanica and surface sediment, collected at eight locations along the Montenegrin coast, were determined. The metal pollution index (MPI) and metal enrichment factor (EF) were then calculated. MPI and EF were lower in sediment than in P. oceanica at the same locations. This was very evident for EF values of Hg and Cd. Based on the Pearson's correlations and EF values, it was possible to conclude that the last two metals' content in the seagrass did not originate from the crustal sources or natural weathering processes