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Fifty years of metallurgical production of zinc and cadmium in Serbia
No full textSrbija ima više nalazišta i aktivnih rudnika polimetaličnih ruda olova i cinka i viševekovnu tradiciju u njihovoj eksploataciji. Sa metalurškom preradom koncentrata cinka počelo se u Srbiji 1955. godine u preduzeću "Zorka", Šabac, a u kombinatu "Trepča", Kosovska Mitrovica 1967. godine. Raspad Jugoslavije, opšte društvene okolnosti i svojinska transformacija doveli su do značajnog opadanja proizvodnje od 1992. godine i do konačne obustave metalurške proizvodnje cinka 1999. godine u "Trepči" i 2002. godine u "Zorki". Tokom rada navedenih pogona, od puštanja u rad pa sve do prestanka rada bilo je više rekonstrukcija i proširenja kapaciteta u oba ova kolektiva, a normalizacija i obnova proizvodnje cinka u Srbiji nije realizovana do 2021. godine.Serbia has plenty of rich sites and active excavation mines of polymetallic ores of lead and zinc and centuries-old practice of their exploitation. In Serbia, the metallurgical processing of zinc concentrate started in 1955 at Zorka company in Šabac, while in the town of Kosovska Mitrovica, it began in 1967 at the Trepča combine. Several factors, including the fall o Yugoslaviam general societal circumstances and ownership transition, lead to a significant decline in production since 1992. It developed to the final halt of zinc's metallurgical production in 1999 at Trepča and in 2002 at Zorka. During the work-life o both production sites, since they opened till they closed, there were several reconstructions and capacity expansions, and all the while, the normalization and renewal of zinc production in Serbia hasn't been realized till 2021
Electrophoretic Deposition of Biocompatible and Bioactive Hydroxyapatite-Based Coatings on Titanium
No full textCurrent trends in biomaterials science address the issue of integrating artificial materials as orthopedic or dental implants with biological materials, e.g., patients' bone tissue. Problems arise due to the simple fact that any surface that promotes biointegration and facilitates osteointegration may also provide a good platform for the rapid growth of bacterial colonies. Infected implant surfaces easily lead to biofilm formation that poses a major healthcare concern since it could have destructive effects and ultimately endanger the patients' life. As of late, research has centered on designing coatings that would eliminate possible infection but neglected to aid bone mineralization. Other strategies yielded surfaces that could promote osseointegration but failed to prevent microbial susceptibility. Needless to say, in order to assure prolonged implant functionality, both coating functions are indispensable and should be addressed simultaneously. This review summarizes progress in designing multifunctional implant coatings that serve as carriers of antibacterial agents with the primary intention of inhibiting bacterial growth on the implant-tissue interface, while still promoting osseointegration
Electrochemical composite bioceramic coatings based on hydroxyapatite, chitosan and polyvinyl alcohol loaded with gentamicin
No full textComposite bioceramic coatings have been attracting increasing attention of the scientific
public in recent decades due to the good potential of their use for medical purposes. The
main goal of this scientific research is to show the characterization of the obtained
hydroxyapatite (HAP), chitosan (CS) and polyvinyl alcohol (PVA) bioceramic composite
coatings loaded with gentamicin (Gent), on titanium (Ti) substrate using the single-step
electrophoretic deposition process. Titanium, traditionally used for the purpose of replacing
parts of damaged bone tissue, has shown good mechanical properties and biocompatibility
through many years of orthopedic practice. Hydroxyapatite provided the HAP/CS/PVA/Gent
composite coating with osteoinductivity, while the presence of chitosan and polyvinyl
alcohol contributed to its adhesive and mild analgesic properties. The antibacterial agent
gentamicin was added to the HAP/CS/PVA composite, which ensured its direct antibacterial
effect at the implantation site. The coatings were deposited using the cathodic electrophoretic
deposition process, with the Ti plate as the cathode, at a constant voltage of 7V, in the range
of the deposition time from 5 to 12 min. To demonstrate the presumed bioactivity,
HAP/CS/PVA/Gent coatings were immersed in simulated body fluid (SBF) at 37⁰C for
periods of 7 and 14 days. Characterization of HAP/CS/PVA/Gent coatings after immersion
was performed through employment of Fourier transform infrared spectroscopy (FTIR), Xray
diffraction (XRD), and field emission scanning electron microscopy (SEM) techniques.
Antibacterial activity was tested by agar diffusion method on two bacterial strains,
Echerichia coli and Staphylococcus aureus with a positive response to both bacterial strains.
The final conclusions of this research suggest a good potential for utilization of
HAP/CS/PVA/Gent bioceramic composite coating, applied through electrophoretic
deposition process on Ti substrate, for medical purposes in the replacement and healing of
damaged bone tissue."
"Composite bioceramic coatings have been attracting increasing attention of the scientific
public in recent decades due to the good potential of their use for medical purposes. The
main goal of this scientific research is to show the characterization of the obtained
hydroxyapatite (HAP), chitosan (CS) and polyvinyl alcohol (PVA) bioceramic composite
coatings loaded with gentamicin (Gent), on titanium (Ti) substrate using the single-step
electrophoretic deposition process. Titanium, traditionally used for the purpose of replacing
parts of damaged bone tissue, has shown good mechanical properties and biocompatibility
through many years of orthopedic practice. Hydroxyapatite provided the HAP/CS/PVA/Gent
composite coating with osteoinductivity, while the presence of chitosan and polyvinyl
alcohol contributed to its adhesive and mild analgesic properties. The antibacterial agent
gentamicin was added to the HAP/CS/PVA composite, which ensured its direct antibacterial
effect at the implantation site. The coatings were deposited using the cathodic electrophoretic
deposition process, with the Ti plate as the cathode, at a constant voltage of 7V, in the range
of the deposition time from 5 to 12 min. To demonstrate the presumed bioactivity,
HAP/CS/PVA/Gent coatings were immersed in simulated body fluid (SBF) at 37⁰C for
periods of 7 and 14 days. Characterization of HAP/CS/PVA/Gent coatings after immersion
was performed through employment of Fourier transform infrared spectroscopy (FTIR), Xray
diffraction (XRD), and field emission scanning electron microscopy (SEM) techniques.
Antibacterial activity was tested by agar diffusion method on two bacterial strains,
Echerichia coli and Staphylococcus aureus with a positive response to both bacterial strains.
The final conclusions of this research suggest a good potential for utilization of
HAP/CS/PVA/Gent bioceramic composite coating, applied through electrophoretic
deposition process on Ti substrate, for medical purposes in the replacement and healing of
damaged bone tissue
Modifikovana hidročađ komine grožđa kao potencijalni adsorbens jona cinka i organskih boja
No full textU okviru ove studije hidročađ komine grožđa ispitana je kao potencijalni adsorbens jona cinka i organskih boja iz vodenih rastvora. Hidročađ pripremljena hidrotermalnom karbonizacijom (HTC) na 20°S, je naknadno alkalno modifikovana v u cilju pospešenja njene sposobnost za uklanjanje ispitivanih polutanata. Pre liminarni adsorpcioni rezultati su pokazali da modifikovana hidročađ pokazuje nešto niži procenat uklanjanja mureksida (14,2%), dok su procenti uklanjanja za cink, metil-crveno i metil-ljubičasto znatno veći (80,68%, 46,53% i 51,23%, redom). Rezultati naše studije su pokazali da komina grožđa može biti razmatrana kom prekursor za proizvodnju efikasnih adsorbenasa primenom HTC procesa.
Ključne reči: hidrotermalna karbonizacija, komina grožđa, cink, organske tretman otpadne vode.
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Sorpciona svojstva tempo - oksidovanih pamučnih lintera prema jonima olova
No full textCeluloza predstavlja jedan od najrasprostranjenijih bio-polimera. Jedinstvena hemijska
struktura kombinovana sa karakteristikama kao što su: hidrofilnost, biokompatibilnost,
biodegradabilnost, netoksičnost i reaktivnost hidroksilnih grupa, pokazuje mogućnost primene
celuloze kao bazičnog materijala za sorpcije različitih jona teških metala iz vodenih ekosistema. U
ovom radu TEMPO-oksidovani pamučni linteri (TOCoL A i B) dobijeni su suspendovanjem početnih
lintera po sistemu TEMPO/NaBr/NaClO. Za dobijanje različitih uzoraka TOCoL-a korišćene su
različite mase 2,2,6,6-tetrametilpiperidin-1-oksil radikala i natrijum-bromida. Nakon dodavanja
rastvora NaClO, održavanja pH suspenzije na 10,55, mešanja, ispiranja vodom i etanolom dobijeni
uzorci čuvani su na 5°C. Na tako modifikovanim uzorcima urađena je karakterizacija i utvrđene su
koncentracije CHO i COOH grupa za TOCoL A (0.1067 mmol/g i 0.2085 mmol/g) i TOCoL B (0.2085
mmol/g i 0.9843 mmol/g). Potom su ispitivana sorpciona svojstva uzoraka A i B prilikom uklanjanja
jona Pb2+ koncentracije 10 mg/l, pri čemu su uzorci analizirani atomskom apsorpcionom
spektroskopijom. Pokazalo se da je maksimalno uklanjanje jona Pb2+ bolje kod uzorka B – 82,1%, za
razliku od uzorka A – 19,3%. Izgled površine vlakana uzoraka pre i nakon sorpcije snimljen je
tehnikom skenirajuće elektronske mikroskopije (SEM), dok je za kvalitativnu analizu funkcionalnih
grupa i strukturnu karakterizaciju materijala koriščena metoda infracrvena spektroskopije sa
Furijeovom transformacijom (FTIR)
Postupak dobijanja ekspandirajućeg materijala sa plastifikatorima iz recikliranog poli(etilen terefatalata) (PET)
No full textSuština ovog Tehničkog rešenja odnosi se na postupak proizvodnje novog protivpožarnog materijala sa plastifikatorima iz recikliranog poli(etilen terefatalata) koji se koristi za izradu prstenova za cevi kao pasivne zaštite od širenja požara. Tehnološki postupak se sastoji iz dve faze. Faza (I) se odnosi na mešanje polivinilhlorida (PVC K70 i PVC K58), sa plastifikatorima kao što su diizononil ftalat (DINP), tri(krezil fosfati) (TKP) (smeša tri(p-krezil fosfat) (TpKP), tri(m-krezil)fosfat (TmKP), tri(o-krezil)fosfat (ToKP) ili čiste komponente), kao i plastifikatori koji su dobijeni iz recikliranog poli(etilen tereftalata) (PET) procesima depolimerizacije PET-a pomoću etilen glikola (PET/EG), propilenglikola (PET/PG) koji se takođe modifikuje pomoću anhidrida maleinske kiselime (MA) i masnih kiselina izolovanih iz sojinog ulja, PET/PG/MA/MKSU, ili samo pomoću MKSU, PET/PG/MKSU, epoksidovano sojino ulje (ESU), 1-heksadecen ili MES, MESU, MELU, MESuU ili MEKU), azodikarbonamid (ADC) i akrilatna emulzija (Ecrylic) a sredstva za ekspandiranje: ekspandirani grafit (EkG), i njegove zamene PET/PG/MA/MKSU/TA, proizvoda dobijenih modifikacijom taninske kiseline (TA) sa PET/PG/MA/MKSU ili PET/PG/MKSU uz korišćenje kiselog katalizatora (KK-SO3H), se dodaje ili u topli mešač ili tokom transporta viskozne mase u ekstruder pomoću dozera sa kontrolisanim protokom pri čemu se masa homogenizuje i profiliše u željeni oblik. Druga faza se odnosi na homogenizovanje mase u ekstruderu i to u prvoj zoni je vreme zadržavanja 30 s - 15 min na temperaturi 90 - 140 ºC, u drugoj zoni 10 s - 10 min na temperaturi 100 - 150 ºC i trećoj zoni vreme zadržavanja 1 s - 60 s na temperaturi 110 - 220 ºC pri čemu se profilisanje materijala vrši korišćenjem alata na izlazu ekstrudera u cilju dobijanja traka širine 1 - 500 mm i debljine 1-100 m
Evaluation of adsorption performance of phosphates removal using Cell-Mg hybrid adsorbent
No full textDue to the high accumulation of nutrients in water (primarily phosphates) because of increased use of fertilizers and plant protection products, it is necessary to apply various techniques for their detection, and then removal. Adsorption is one of the promising techniques to removing them. Magnetite (MG) modified cellulose membrane (Cell-MG), obtained by reaction of 3-aminosilane and subsequently with diethylenetriaminepentaacetic acid dianhydride functionalized waste Cell fibers (Cell-NH2 and Cell-DTPA, respectively), and amino-modified diatomite was used for phosphate ions removal from water. Cell-MG membrane was structurally and morphologically characterized using SEM and TEM techniques. The influences of operational parameters, i.e. pH, contact time, temperature, and the mass of adsorbent on adsorption and kinetics were studied in a batch system. The calculated capacities of 79.08 mg g-1 at 45°C for phosphate ions were obtained from non-linear Langmuir model fitting. The reusability of adsorbent and results from wastewater purification showed that Cell-MG could be used as general-purpose adsorbent. Based on the kinetic studies the adsorption process follow the pseudo second-order model. Thermodynamic parameters showed that the adsorption process is endothermic and spontaneous
Opportunities for Ni phytomining in Serbia: extraction of nickel salts from the hyperaccumulating plant Odontarrhena muralis
No full textPhytomining is a technique that aims to obtain metal(oid)s or their products using hyperaccumulating plant species that grow on substrates rich in heavy metals, but not enough to justify conventional mining. After harvesting, the biomass is combusted and the ash is used as bio-ore for the production of pure metal(oid)s or their salts. Most hyperaccumulating plants accumulate Ni, which occurs naturally in high concentrations in ultramafic soils. A large number of Ni hyperaccumulators are found in the genus Odontarrhena, which is most commonly used in phytomining studies. In order to obtain the largest amounts of Ni and the salts of the higher purity, it is necessary to choose the most suitable ash processing treatment. This study shows results of obtaining Ni salts from the ash of Odontarrhena muralis by hydrometallurgical process in the form of ammonium nickel sulfate hexahydrate, Ni(NH4)2(SO4)2x6H2O - (ANSH). Odontarrhena muralis from ultramafic sites at West Serbia accumulates Ni at concentrations of 3300 mg kg-1 and is a good candidate for the phytomining process. By biomass combustion, during which biomass weight decreases for 92.7%, ash was obtained as a suitable raw material for Ni extraction. Out of gained mass of crude ash, 11,71% was yielded as ANSH crystals.The obtained purity of ANSH was 73%, which is slightly lower compared to similar studies, but good enough to show the potential for phytomining application. By optimizing the purification process that precedes precipitation of the ANSH crystals, the purity of recovered crystals can be additionally increased, influencing the economic feasibility of the process. Moreover, by selecting appropriate agronomic measures, it is possible to obtain biomass of O. muralis with increased concentration of Ni in aboveground parts, which would increase the initial concentration of Ni in bio-ore that is entering the extraction process
Possibility of using limestone from “Pješivački do”-Danilovgrad deposit as filler in various industry branches
No full textThis paper presents results of investigations of the possibility of using “Pješivački Do”-Danilovgradlimestone as filler in various industry branches. Micronization methods, granulometric composition, oil and water absorption and degree of whiteness were investigated, and chemical and thermal analyses (DT/TG) were performed.Physico- chemical properties of this limestone classify it among high quality carbonate raw materials with high CaCO3 content of 98.65%, as well as low MgCO3 content of 0.95% and low silicate content (SiO2 0.23%). Its quality satisfies requirements of standards on using of calcium carbonate as filler in industry of paints and coatings; paper industry; rubber and PVC industry; in production of cattle feed; glass industry; production of mineral fertilizers and sugar industry. Due to the low degree of whiteness (87,6%) Pješivački Do”limestone cannot be used in pharmaceutical and cosmetics industry. Due to relatively high content of Cr (10 ppm) as heavy metal, content of S (0,19%), as well as biogenic elements P2O5 (0.030%), “Pješivački Do” limestone cannot be used in, foundry industry and metallurgy and for neutralization of acidic soils
