ritnms
Not a member yet
1551 research outputs found
Sort by
Definisanje uslova razdvajanja (separacije), posle mlevenja, u mineralnom sistemu pirofilita-kvarca u zasebne proizvode, ležišta „Parsović“ – Konjic (BiH)
No full textLežište pirofilitskog škriljca “Parsović” nalazi se u blizini Konjica (Federacija BiH) Republika Bosna i Hercegovina. Overene rezerve rude u ležištu se kreću na nivou od 18.000.000t, pri čemu je u ležištu konstatovano prisustvo sledećih minerala pirofilit - Al2Si4O10(OH)2 - sericit KAl2(AlSi3O10)(OH)2oko 50-55%, kvarca SiO2 od 30-35%, kalcita CaCO3 od 5-10%, dolomit CaMg(CO3)2 do 5%, kaolinit (Al2Si2O5(OH)4) u tragovima. Pre ratova devedesetih godina društveno preduzeće “Rudar”-Konjic se bavilo eksploatacijom pirofilitske rude, koja se posle postupaka pripreme koristila kao punioc u industriji papira, boja i lakova. U XXI veka je došlo do privatizacije postrojenja i ležišta i novi vlasnik A.D. Harbi sa sedištem u Sarajevu, je odlučio da unapredi postojeća tehnološka znanja i da osvoji nova i da na taj način proširi oblast primene pirofilita u različitim privrednim granama i zaštiti životne okoline. Kako pirofilit spada u grupu alumosilikata, to je A.D. Harbi po analogiji sa drugim alumo-silikatima (zeolitima, bentonitima itd..) odlučio da ispita mogućnost primene pirofilita u poljoprivredi (kao dodatka zemljištu i dodatka stočnoj hrani), u ekologiji za prečišćavanje raznih vrsta otpada i agenasa u sva tri agregatna stanja. Za ovu svrhu nepohodno je da se ruda pirofilita usitni postupcima mikronizirajućeg mlevenja, u keramičkim mlinovima sa keramičkim meljućim telima, kako ne bi došlo do kontaminacije. Prisustvo kvarca sa masenim učešćem od 30-35% u različitim klasama krupnoće u rudi pirofilita predstavlja problem za primenu ovakvog proizvoda u poljoprivredi, naročito kao potencijalnog dodatka stočnoj hrani. Naime, krupnozrni kvarc u samlevenom proizvodu, sa veoma oštrim ivicama i velikom tvrdoćom (po Mohsu oko 7) i veoma velikom hemijskom stabilnošću (ostaje nerastvoran u želudcu) svojim prisustvom u digestivnom traktu mehanički oštećuje organe za varenje pre svih creva. Osim toga zbog velike razlike u tvrdoći između pirofilita (tvrdoća po Mohsu 1-1,5) i kvarca (tvrdoća po Mohsu oko 7), prilikom mlevenja pirofilit se brzo mikronizira i prelazi u najsitnije klase, dok se kvarc u keramičkom mlinu veoma teško usitnjava i ostaje koncentrisan u krupnijim klasama. Ukoliko se ipak želi da se kvarc samelje u keramičkom mlinu na veliku finoću to bi iziskivalo veliku utrošak električne energije I veliku potrošnju meljućih tela (kugli i obloga mlina), koji bi svojim prisustvom u samlevenoj sirovini dodatno onečistili gotov proizvod - pirofilit i na taj način mu smanjili upotrebnu vrednost. Iz svih tih razloga potrebno je postupak mlevenja-kalsiranja rude pirofilita izvesti tako da se izvrši separacija-uklanjanje krupnozrnog kvarca
Mineralogy and crystallographic properties of HEU-type zeolitic tuff from the Novakovic deposit, Bosnia and Herzegovina
No full textThis paper presents mineralogical and crystallographic characterization of the zeolitic tuff from the Novakovic deposit, Republic of Bosnia and Herzegovina. The zeolitic tuff is of a whitish color composed of Ca-clinoptilolite and an amorphous phase (volcanic glass and amorphous SiO2). The zeolitic tuff was analyzed by X-ray diffraction of the polycrystalline sample (XRPD), scanning electron microscopy and energy dispersive spectroscopy (SEM/EDS), and differential thermal and thermogravimetric (DTA/DTG) methods. According to the results obtained, it can be concluded that the studied zeolitic tuff is composed of Heu-type minerals. Based on the chemical analysis, thermal treatment and XRPD analysis it was determined that this is a mineral Ca-clinoptilolite. Thermal analysis in the temperature range from 300 up to 700 degrees C showed that the examined zeolite minerals from the Nova-kovic deposit are stable up to the temperature of 600 degrees C. The crystal structure of Ca-clinoptilolite has been refined in the centrosymmetric space group C2/m (S.G. 12) with disordered distribution of Al and Si in the tetrahedral framework. The unit-cell parameters are as follows: a = 17.662 angstrom, b = 17.874 angstrom, c = 7.402 angstrom, beta = 116.32 degrees and V = 2122.73 angstrom(3). The basic structural motif is represented by four channels. Three channels are composed of eight-membered rings, and one of ten-membered rings. The ten-membered (channel A) and one eight-membered channel (B) are parallel to the crystallographic axis c, and the other eight-membered channel is parallel to the a-axis. Ca-clinoptilolite comprises approximately 90% of the studied zeolite tuff while the rest 10 % is the amorphous phase. The overall cation exchange capacity (CEC) amounts to 187 mmolM(+)/100 g, and calcium represents the most abundant cation in the studied sample. The atomic ratios of Si/Al, Na+/(Na++K+), and Ca2+/(Ca2++Mg2+) are as follows: 4.36, 0.14, and 0.55, respectively. The zeolite tuff is both thermally and structurally stable and has applications in various areas of industry and agriculture
Gentamicin-Loaded Bioactive Hydroxyapatite/Chitosan Composite Coating Electrodeposited on Titanium
No full textComposite coating of antibiotic gentamicin (Gent), natural polymer chitosan (CS), and hydroxyapatite (HAP) was successfully assessed by applying the electrophoretic deposition (EPD) technique. EPD was performed under optimized deposition conditions (5 V, 12 min) on pure titanium plates, to obtain HAP/CS and HAP/CS/Gent composite coatings in a single step from three-component aqueous suspension, with favorable antibacterial properties. Composite coatings were characterized by X-ray diffraction (XRD), field emission scanning electron microscopy, Fourier transform infrared spectroscopy, thermogravimetric analysis, and X-ray photoelectron analysis, confirming the formation of composite HAP/CS and HAP/CS/Gent coatings on the titanium surface, which is due to intermolecular hydrogen bonds. Employing the XRD technique, HAP was detected by obtaining the characteristic diffraction maximums. Good antibacterial activity of the composite coating loaded with antibiotic (HAP/CS/Gent) was confirmed against Staphylococcus aureus and Escherichia coli, pointing to the high potential for bioapplication. Introduction of gentamicin in HAP/CS/Gent coating caused very mild cytotoxicity in the tested cell lines MRC-5 and L929. MTT testing was used to evaluate cell viability, and HAP/CS was classified as noncytotoxic
Trokomponentne bioaktivne prevlake sa gentamicinom elektroforetski taložene na titanu
No full textElektroforetsko taloženje je efikasna elektrohemijska metoda za dobijanje višekomponentnih
biokeramičkih prevlaka na metalnom supstratu. Za formiranje biomaterijala za
koštane implantate, najbolji rezultati su dobijeni kod prevlaka koje predstavljaju kombinaciju
mineralne faze i polimera. U cilju dobijanja bioaktivnih prevlaka na titanu primenom
elektroforetskog taloženja, urađena je optimizacija uslova taloženja iz trokomponentne
vodene suspenzije hidroksiapatita (HAP), hitozana (CS) i antibiotika gentamicina (Gent), pri
različitim konstantnim vrednostima napona i vremena taloženja. Karakterizacija prevlaka je
izvršena primenom rendgenske difrakcione analize (XRD) i rendgenske fotoelektronske
spektroskopije (XPS). Citotoksičnost dobijenih prevlaka je ispitana MTT testom, dok je
antibakterijska aktivnost prevlake sa gentamicinom potvrđena primenom testa u suspenziji.
Na osnovu dobijenih rezultata, potvrđeno je da trokomponentna biokompatibilna prevlaka
HAP/CS/Gent ima veliki potencijal za upotrebu u biomedicini.Electrophoretic deposition is a suitable method for obtaining multicomponent bioceramic
coatings on titanium (Ti). For hard tissue implants, the best results are achieved for the
coating composed of mineral phase and a polymer. First step in producing bioactive
coatings on Ti using electrophoretic deposition process was the optimization of deposition
parameters for three-component aqueous suspension, containing hydroxyapatite (HAP),
chitosan (CS) and gentamicin (Gent), at constant values of applied voltages and different
deposition times. The coatings obtained were characterized by X-ray diffraction (XRD) and
X-ray photoelectron spectroscopy (XPS). Cytotoxicity of the coatings was evaluated by MTT
assay, and the antibacterial activity of gentamicin loaded coating was verified using test in
suspension. Based on the experimental results, the formation of a new HAP/CS/Gent
composite coating with future prospect for biomedical use was confirmed
Biokompatibilne kompozitne prevlake hidroksiapatit/hitozan sa gentamicinom na titanu taložene iz vodene suspenzije
No full textПроналазак представља нов производ, биокомпатибилне композитне превлаке хидроксиапатит/хитозан (HAP/CS) и хидроксиапатит/хитозан/гентамицин (HAP/CS/Gent) на површини титана, које су добијене поступком електрофоретског таложења из водене суспензије при константном напону.
Овај поступак представља ефикасан начин за добијање униформне превлаке уз контролу дебљине и морфологије финалног производа у коју је успешно инкорпорисан антибиотик гентамицин, а превлаке су добијене у једном ступњу, таложењем из трокомпонентне водене суспензије
Preparation and antimicrobial activity of polyethylene composite with silver-doped fluorapatite
No full textThe high-density polyethylene/silver-doped fluorapatite composite
(HDPE/AgFAP) with 1 wt% of AgFAP was produced using a twin screw
extruder. Characterization studies of XRD and TEM results showed that
AgFAP particles were drowned and partially dispersed in the polymer.
Antimicrobial study has demonstrated that composite exhibits antimicrobial
activity in vitro against the S. aureus
Influence of the basalt structure and properties on development the cavitation damage
No full textThis paper analyzes the formation of cavitation damages depending on the technology of fabrication, structure and properties of basalt from the Vrelo-Kopaonik deposit. The methodology for monitoring the level of damage caused by cavitation and estimation the material life span base on parameters was developed: change in the mass loss, measurement the degradation level of the sample surface, dynamics of the formation of pits, changes in their average area surface, determination the line profile. A change in the surface morphology with the test time was followed by a scanning electron microscopy. The level of surface degradation of samples was quantified using the image analysis. The results indicate that the cast basalt has a high degree of cavitation resistance
The influence of process temperature on structural characteristics of the obtained hydrochars
No full textIn recent years, a technique for conversion of waste biomass into solid carbon material (hydrochar) with high energy potential, become very attractive. This process is known as hidrothermal carbonization (HTC). The conversion of raw biomass into the hydrochars is called "wet" pyrolysis since conversion take place at moderate 1 temperatures and pressures, while subcritical water is used as the process medium. Major influences on the structure of the obtained product have different process parameters such as pressure, temperature, reaction time, biomass type and biomass and water ratio. Based on the literature review, it can be concluded that the temperature has the greatest influence on the structural changes of the obtained hydrochars and therefore stands out as the most important parameter of the HTC process. It has been shown that increasing of reaction temperature increases the degradation of biomass, thus the yield, ash and volatile content in the resulting hydrochars is reduced. On the other hand, the carbon content, fuel properties and energy density are increased. This suggests that temperature variation during the HTC process provides hydrochars with improved fuel characteristics in relation to the feedstock, whereby the utilization value of waste biomass was significantly improved. This is the first report of HTC conversion of waste substrates for mushrooms cultivation and comparison of obtained results with literature data
Natural and Modified Zeolite-Alginate Composites. Application for Removal of Heavy Metal Cations from Contaminated Water Solutions
No full textIn present paper, the influence of the initial pH and concentration of Pb2+ on its adsorption by the natural (NZA) and Fe(III)-modified zeolite-alginate beads (FeA) was studied. Results showed that modification of the starting materials have a positive effect on their adsorption capacities (102 and 136 mg/g for the NZA and FeA, respectively). After encapsulation, the mechanism of lead adsorption by both adsorbents was changed and ion exchange dominates. The best adsorption was achieved for initial pH > 3.8. Cation exchange capacity, structural properties, and hydrophobicity of samples were also determined, and the presence of the alginate has no significant influence on investigated properties of samples. Experiments on wastewater from tailings of lead and zinc mine Grot, Serbia, showed that after treatment with both adsorbents, the content of the most abundant heavy metals (Pb, Zn, Hg, and Mn) significantly decreased
Applying multi-criteria analysis for preliminary assessment of the properties of alginate immobilized Myriophyllum spicatum in lake water samples
No full textThe preliminary assessment of the properties of alginate immobilized aquatic weed Myriophyllum spicatum beads-MsAlg in a multi-element system of nine Serbian lakes water samples was done. Herein, the results obtained in the biosorption experiment with MsAlg contents of twenty-two elements analysed by inductively coupled plasma-optical emission spectrometry, biosorption capacity, element removal efficiency, total hardness (TH) and quality index of water (WQI) are presented. Scanning electron microscopy with energy dispersive X-ray spectroscopy was used for the characterization of M. spicatum and its beads. The study showed that aluminium, magnesium and strontium were adsorbed by MsAlg in the water samples from all examined lakes; barium and iron in the water samples from six lakes. The overall average efficiency of MsAlg in biosorption of elements was in the following order: Al > Ba > Sr > Fe > Mg (58.6, 51.7, 48.2, 23.9 and 17.7%, respectively). The increase of TH and WQI values after the biosorption was noticed in all studied lake water samples. The most significant correlations for pH were regarding the contents of B, Mg and Ca, whereas WQI was highly correlated to the contents of B and Mg, and pH. The complexity of the obtained data was explained by Cluster Analysis and Principal Component Analysis, which showed good discrimination capabilities between the water samples taken from different locations. Considering that the invasive M. spicatum is natural, widespread and that its immobilization is cheap and eco-friendly, presented findings could be helpful in further assessment of MsAlg beads for its potential use as biofilter