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Geochemical distribution of selected elements in flotation tailings and soils/sediments from the dam spill at the abandoned antimony mine Stolice, Serbia
No full textMaterials held within mine tailings pose a serious risk to the environment in cases of tailings dam failure. Collapse of the tailing dam at the Stolice antimony mine in West Serbia caused a spilling of tailing slurry into the nearby river watersheds. Medium-term effects of As, Pb, Sb, Zn, and Cd from the tailings material that remained in the flooded zone 3 years after the initial exposure were evaluated. Mobility of these elements was determined by analyzing their distribution between exchangeable, reducible, oxidizable, and residual phases. Results indicate that Fe-Mn oxides represent important sinks for As, Cd, Pb, and Sb. Multivariate statistical analysis revealed that concentrations of the analyzed elements were related to sand-sized fractions, as they tended to adsorb or co-precipitate as coatings on larger particles (particularly feldspar and quartz) upon the change of redox conditions. Assessment of the most relevant physico-chemical factors, metal(loid) concentration, and mobility can be used as tool to characterize the degree of contamination of impacted sites. Percentage of sand-sized particles, content of investigated metal(loid)s, and their amount in the reducible fractions are factors determining the best remediation techniques for the area impacted by tailing spill
Application of the Flotation Tailings as an Alternative Material for an Acid Mine Drainage Remediation: A Case Study of the Extremely Acidic Lake Robule (Serbia)
No full textFlotation tailings rich in carbonate minerals from the tailings deposit of the copper mine Majdanpek (Serbia) were applied for neutralization of the water taken from the extremely acidic Lake Robule (Bor, Serbia). Tests conducted in Erlenmeyer flasks showed that after neutralization of the lake water to pH 7, over 99% of aluminum (Al), iron (Fe), and copper (Cu) precipitated, as well as 92% of Zn and 98% of Pb. In order to remove residual Mn and Ag, the water was further treated with NaOH. After treatment with NaOH, all concentrations of the metals in the lake water samples were below discharge limits for municipal wastewater according to the national legislation of the Republic of Serbia. The results of this work suggest that mining waste could be used for active neutralization of the acid mine drainage. The use of the mining waste instead of lime could reduce the costs of the active treatment of the acid mine drainage
Assessing the Bioactivity of Gentamicin-Preloaded Hydroxyapatite/Chitosan Composite Coating on Titanium Substrate
No full textThe electrophoretic deposition process (EPD) was utilized to produce bioactive hydroxyapatite/chitosan (HAP/CS) and hydroxyapatite/chitosan/gentamicin (HAP/CS/Gent) coatings on titanium. The bioactivity of newly synthesized composite coatings was investigated in the simulated body fluid (SBF) and examined by X-ray diffraction, Fourier transform infrared spectroscopy, and field emission scanning electron microscopy. The obtained results revealed carbonate-substituted hydroxyapatite after immersion in SBF, emphasizing the similarity of the biomimetically grown HAP with the naturally occurring apatite in the bone. The formation of biomimetic HAP was confirmed by electrochemical impedance spectroscopy and polarization measurements, through the decrease in corrosion current density and coating capacitance values after 28-day immersion in SBF. The osseointegration ability was further validated by measuring the alkaline phosphatase activity (ALP) indicating the favorable osseopromotive properties of deposited coatings (significant increase in ALP levels for both HAP/CS (3.206 U mL(-1)) and HAP/CS/Gent (4.039 U mL(-1)) coatings, compared to the control (0.900 U mL(-1))). Drug-release kinetics was investigated in deionized water at 37 degrees C by high-performance liquid chromatography coupled with mass spectrometry. Release profiles revealed the beneficial "burst-release effect" (similar to 21% of gentamicin released in the first 48 h) as a potentially promising solution against the biofilm formation in the initial period. When tested against human and mice fibroblast cells (MRC-5 and L929), both composite coatings showed a noncytotoxic effect (viability >85%), providing a promising basis for further medical application trials
The chemical characterization of peach kernels (Prunus persica L.)
No full textIstrazivanjima u okviru ove doktorske disertacije na osnovu sadrţaja pojedinih fitohemikalija izvršena je hemijska karakterizacija semena 25 sorti/genotipova breskve razliĉitog genetiĉkog i geografskog porekla gajenih pod istim klimatskim uslovima na teritoriji Srbije u okviru kolekcije oglednog dobra „Radmilovac‖ Poljoprivrednog fakulteta Univerziteta u Beogradu. U cilju utvrĊivanja sliĉnosti i razlika izmeĊu pojedinih genotipova breskve, kao i odreĊivanja potencijalnih biomarkera njihovog genetiĉkog i geografskog porekla, istraţivanja su obuhvatila analizu varijabilnosti standradnih sorti (poreklom iz SAD i Italije), perspektivnih hibrida (nastalih ukrštanjem standardnih sorti) i nekoliko genotipova vinogradarske breskve kao autohtone sorte iz Srbije. Osim podele po poreklu, ispitivani genotipovi breskve razlikovali su se i po vremenu sazrevanja ploda. Gasna hromatografija sa plameno-jonizacionim detektorom (Gas Chromatography with Flame Ionization Detector, GC-FID) korišćena je za odreĊivanje sastava masnih kiselina u uzorcima semena breskve. Bez obzira na razliĉitost izmeĊu genotipova, ulje semena breskve ima sliĉan sastav masnih kiselina koji se najvećim delom sastoji od nezasićenih masnih kiselina, oleinske i linolne kiseline. Razlika izmeĊu sorti/genotipova breskve se ogleda samo u razlici u procentualnim koncentracijama najzastupljenijih masnih kiselina. Ulje semena breskve ima nizak ukupni sadrţaj zasićenih masnih kiselina, manji od 15%, i to uglavnom sadrţi palmitinsku i stearinsku kiselinu. Fenolni profil semena breskve odreĊen je ultra-visokoefikasnom teĉnom hromatografijom spregnutom sa hibridnim masenim spektrometrom (Ultra High-Perfomance Liquid Chromatography coupled with a hybrid mass spectrometer - Linear Trap Quadrupole and OrbiTrap mass analyzer, UHPLC-LTQ OrbiTrap MS/MS). U uzorcima semena breskve detektovane su razliĉite klase fenolnih jedinjenja i nekoliko organskih kiselina sa manjim brojem C-atoma. Od fenolnih jedinjenja semena breskve u najvećoj koliĉini sadrţe katehin i šest fenolnih kiselina: protokatehuinsku, p-hidroksibenzoevu, p-hidroksifenilsirćetnu, hlorogenu, p-kumarinsku i ferulinsku kiselinu. Kvantifikacija saharida izvršena je upotrebom visoko-efikasne anjonske hromatografije sa elektrohemijskom detekcijom (High-Performance Anion Exchange Chromatography with Pulsed Amperometric Detection, HPAEC-PAD...The investigations in scope of this doctoral dissertation were based on the content of a several phytochemicals and it comprised chemical characterization of kernels of 25 peach cultivars/genotypes differing in genetic and geographical origin cultivated under the same climatic conditions in the territory of Serbia within a collection of the „Radmilovac‖ Experimental Station of the University of Belgrade - Faculty of Agriculture. In order to determine the similarities and differences between the individual cultivars/genotypes of the peach, as well as to identify potential biomarkers of their genetic and geographical origin, the research included an analysis of the variability of standard cultivars (originating in the USA and Italy), promising hybrids (created by standard cultivars cross-breeding) and several vineyard peach genotypes as autochthonous cultivars from Serbia. Except from this division, the examined genotypes of the peach differed according to the ripening time. Gas chromatography with flame ionization detector (GC-FID) was used to determine the composition of fatty acids in samples of the peach kernels. Regardless of the difference between genotypes, the peach kernel oil has the similar fatty acid composition, which the most consists of unsaturated fatty acids, oleic and linoleic acids. Variation between varieties/genotypes of peach is only seen in the difference in the percentage concentrations of the most abundant fatty acids. The kernel oil has a low total saturated fatty acid content less than 15%, which is mainly composed of palmitic and stearic acids. The phenolic profile of peach kernels was determined by ultra-high-perfomance liquid chromatography coupled with a hybrid mass spectrometer (UHPLC-LTQ OrbiTrap MS/MS). In samples of peach kernels, different classes of phenolic substances and several organic acids with small number of C atoms were detected. Among phenolic compounds, the most abundant in peach seeds were catechin and six phenolic acids: protocatechuic, p-hydroxybenzoic, p-hydroxyphenylacetic, chlorogenic, p-coumaric and ferulic acids. The quantification of saccharides was perfomed using high-performance anion exchange chromatography with pulsed amperometric detection (HPAEC-PAD)..
Investigation of potentially toxic elements in urban sediments in Belgrade, Serbia
No full textConcentrations of 10 potentially toxic trace elements were measured in soil samples collected from 18 sites in urban areas of Belgrade, the capital and the largest city in Serbia. Samples were analysed in order to assess the extent of soil contamination and to distinguish natural and anthropogenic input. The results demonstrated a general Zn, Pb, and Cd enrichment in surface samples, hence, after comparison with guidelines, it has been determined that there is a potential risk for human health. In the surface and buried samples, traces of cooper were detected. The highest concentrations of Cr (121 +/- 12.3 mg/kg) and Ni (94.9 +/- 12.6 mg/kg) were found at a sediment depth of 2 m and should be ascribed to geogenic sources. The results of HCA and PCA analysis supported a natural origin of Co, Cu, Mn, Cr, and Ni, while Cd, Zn, and Pb originated from anthropogenic inputs. Based on the pollution indices, Cd made the most dominant contribution, posing a high contamination risk in the studied area. Results of Nemerow pollution index (PIN) and potential ecological risk index (PER) demonstrated that pollution by heavy metals in sediments on several sites is moderately intense
Svojstva PVC-a i plastičnih materijala i značaj njihove reciklaže
No full textHaving in mind increasing of environmental pollution, serious attention is being paid to plastic waste
recycling to reduce environmental pollution. This paper presents the basic properties of polyvinyl
chloride (PVC), its use and PVC waste treatment methods. PVC waste can be treated in 3 ways: by
recycling, incineration and landfilling. The use of new and modern technologies in plastics waste
recycling can reduce the level of toxic substances emission that adversely affects the environment.Imajući u vidu da se životna sredina sve više zagađuje, danas se ozbiljna pažnje posvećuje reciklaži
kojom se može iskoristiti plastični otpad i time ujedno smanjiti zagađivanje okoline. U radu su
prikazane osnovna svojstva polivinil-hlorida (PVC), njegova upotreba kao i načini tretiranja PVC
otpada. PVC otpad se može tretirati na 3 načina: reciklažom, spaljivanjem i skladištenjem u
deponijama. Korišćenjem novih i savremenih tehnologija u procesu reciklaže otpadne plastike
smanjuje se nivo oslobađanja toksičnih materija koje negativno utiču na životnu sredinu
Surfactant modified natural zeolites as adsorbents for contaminants of emerging concern: Non-Steroidal Anti-Inflammatory drugs
No full textIn this study, composites of two zeolite-rich rocks were modified with cationic surfactants cetylpyridinium chloride (containing one hydrophobic tail) and Arquad® 2HT-75 (having two hydrophobic tails) and tested for the adsorption of contaminants of emerging concern – diclofenac, ibuprofen, naproxen, and ketoprofen.
Modifying a clinoptilolite- and phillipsite-rich tuffs with different amounts of selected surfactants resulted in the preparation of composites with monolayer or bilayer of each surfactant at zeolitic surfaces. Starting materials and prepared composites were characterized by ATR–FTIR and STA coupled with EGA. The point of the zero charge was determined for starting materials and composites, providing the information of materials surface properties and their buffering capacities. Zeta potential measurements confirmed that the negative charge of the natural zeolites was compensated and close to zero when surfactants formed monolayers at the zeolitic surface or reversed to positive when bilayers of surfactants are present at the zeolitic surface. Extensive washing of the composites and repeated zeta potential measurements have shown that surfactants were unstable at the zeolite surface, especially in bilayer formation. However, composites with bilayers prepared using the two-tailed surfactant Arquad® 2HT-75 had excellent stability. These results suggested that SMNZs could be tailored for safe applications for water treatment purposes.
The capabilities of the prepared sorbents to adsorb four drugs were estimated by the determination of adsorption isotherms and kinetic runs. Maximum adsorption capacities, obtained from the Langmuir model, were in the range from 1-35 mg/g, where the best results were achieved with composites containing bilayers of surfactants at the zeolitic surfaces. Physicochemical properties (pKa and log Kow) of investigated drugs helped explain the mechanism of their adsorption by SMNZs. Between the two used zeolite-rich tuffs, composites prepared using clinoptilolite-rich tuff had the better performance. As far as the two surfactants are considered, composites with cetylpyridinium chloride gave better results. Using the best performing adsorbent, drug adsorption isotherms were conducted in the natural water collected from Grindstone creek (Columbia, Missouri, USA) to have a more realistic system.
Consequently, a slight decrease in diclofenac and ibuprofen adsorption was observed, while adsorption of NAP and KET was quite similar. Kinetic runs were performed in distilled water as well as in the presence of inorganic ions (sulfates and bicarbonates), and these interfering agents have caused an adsorption decrease for bilayer composites. For comparison reasons, kinetic runs for each drug were performed using activated carbon under similar experimental conditions. ATR-FTIR analysis and zeta potential measurements were performed on composites after adsorption of drugs, confirming the presence of drugs at zeolitic surfaces without any change of structures of composites
Effect of corn straw pretreatment on efficiency of biogas production process: Computer simulation
No full textAnaerobic digestion is a natural process of organic material degradation by
different kinds of microorganisms in the absence of oxygen. This process is used for
industrial purpose to manage waste streams or to produce biogas. It gives a major
contribution in reduction of harmful effects of organic waste disposal to the environment.
The aim of agricultural waste pretreatment in biogas production is to decrease the
retention time, improve utilization of raw material and improve the overall productivity
and energy efficiency of the production process. In this paper the effects of combined
chemical and mechanical pretreatment of corn straw biomass on biogas yield during
anaerobic digestion of the feedstock were analyzed. The impact of pretreatment and
process parameters in biogas production was analyzed by process simulation using the
software SuperPro Designer. Using this tool a decrease of degradation time with an
increase in biogas yield was shown
Review of the past, present, and future of the hydrometallurgical production of nickel and cobalt from lateritic ores
No full textLaterite ores are becoming the most important global source of nickel and cobalt. Pyrometallurgical processing of the laterites is still a dominant technology, but the share of nickel and cobalt produced by the application of various hydrometallurgical technologies is increasing. Hydrometallurgy is a less energy-demanding process, resulting in lower operational costs and environmental impacts. This review covers past technologies for hydrometallurgical processing of nickel and cobalt (Caron), current technologies (high-pressure acid leaching, atmospheric leaching, heap leaching), developing technologies (Direct nickel, Neomet) as well as prospective biotechnologies (Ferredox process)
Atmospheric leaching of copper from oxide-sulfide ore using sulfuric acid
No full textVisoka fleksibilnost, ekonomičnost i ekološka prihvatljivost hidrometalurških operacija nude mogućnost za selektivno dobijanje metala u ranim fazama tehnološkog procesa. To omogućava primenu hidrometalurških operacija u preradi ruda koje, zbog kompleksnog sastava ili niskog sadržaja metala, nisu pogodne za pirometalurški tretman. Nasuprot sulfidnim mineralima, za luženje oksidnih ruda nije potrebno prisustvo oksidansa. U ovom radu prikazani su rezultati ispitivanja uticaja temperature na stepen izluženja bakra iz piritno-halkopiritnog koncentrata rastvorom sumporne kiseline pri atmosferskom pritisku. Na osnovu dobijenih rezultata utvrđeno je da povećanje temperature luženja značajno doprinosi povećanju efikasnosti izluženja pri čemu nakon 6 sati luženja na 40°C postignuta efikasnost je iznosila 90,6%.High flexibility of hydrometallurgical operations as well as economic and environmental acceptability, offer the opportunity to selectively obtain metals in the early stages of the processing. This enables the application of hydrometallurgical operations in processing of ores which, due to their complex composition or low copper content, are not suitable for pyrometallurgical treatment. In contrast to sulfide minerals, leaching of oxide ores does not requires presence of oxidizing agent. This paper presents the results of influence of temperature on the leaching degree of copper from pyritechalcopyrite concentrate by sulfuric acid solution at atmospheric pressure. According to the obtained results, it was found that an increase in the leaching temperature significantly contributes to the increase in the leaching efficiency, where after 6 hours of leaching at 40°C achieved efficiency was 90.6%