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Mikronizirajuće mlevenje pirofilita-Parsović-Konjic (BiH)
No full textMikronizacija pirofilita je veliki tehnološko-tehnički problem, iz razloga što klasične mašine za usitnjavanje, ne mogu, svojim procesnim uslovima, da ga mikroniziraju do finog i posebno veoma finog granulometrijskog sastava, koji je neophodan za nove savremene domene industrijke primene. Iz ovih razloga, neophodno je dobro poznavanje njihovih fizičko-hemijskih, mineraloških, mehaničkih osobina, i posebno mehanizama procesa njihovog finog usitnjavanja (mikronizacije).Detaljnim istraživanjima kinetike mikronizirajućeg mlevenja pirofilita, dobijeni su elementi za određivanje efikasnosti rada vibracionih i ultra-centrifugalnih mlinova, a samim tim stečeni su uslovi za definisanje kako tehnoloških parametara mikronizacije, tako i parametara proizvoda mikronizacije. U isto vreme, na osnovu detaljne fizičko-hemijske, mineraloške i rentgenske karakterizacije mikroniziranih proizvoda pirofilita, uočene su određene fizičko-hemijske promene u njihovoj strukturi (prelaz pirofilita u amorfno stanje), što je sigurno posledica rada pomenutih mlinova
Applicability of biosorption technology in real systems
No full textBiosorption is a branch of biotechnology emerged in order to provide low cost wastewater treatment and to minimize waste disposal at the same time. It is based on ability of biological materials to bind and to concentrate various pollutants from the aqueous solutions. Main advantages of biosorption process are efficiency, simplicity and availability of biomass. As bio-adsorbents many materials with biological origin have been investigated and their biosorption capacities have been reported in numerous research papers. Although the biosorption is often presented as a promising clean up technology for more than two decades, unfortunately most of the biosorption processes are still at laboratory scale. This paper investigates the reasons of lack of practical application and commercial success of biosorbents
Potential of Equisetum ramosissimum Desf. for remediation of antimony flotation tailings: a case study
No full textA flooding event caused collapsing of the Stolice flotation tailing dam and spilling of large volumes of sludge into environment. Urgent remediation measures have not been applied due to the lack of financial resources. Remediation values for Sb, Zn, and Pb in the flotation tailing samples were exceeded 20.5, 4.2, and 1.15 times, respectively, emphasizing the need for remediation. Plants growing on mine spoils represent useful tools for environmental monitoring and soil remediation. The appearance of Equisetum ramosissimum as a dominant colonizer on the flotation tailings indicates that biological reclamation of the site is possible. Equisetum ramosissimum shows the ability to phytostabilize and immobilize available fractions of Fe, Mn, Zn, Pb, and Sb. Transfer rate of metals from roots to shoots reveals exclusion of elements from the shoots, preventing their further spreading through the food chain. The results of this study show that E. ramosissimum can be an additional tool for environmental monitoring and remediation of flotation tailings after hazardous events
Characterisation of Purified Gypsum and Insoluble Impurities Obtained from Phosphogypsum Waste
No full textIn this study, the chemical and phase composition of two samples of phosphogypsum from the waste dumps of the Industry of Chemical Products "Elixir - Prahovo" (Serbia) were examined, as well as the possibility of recrystallization of gypsum from an aqueous suspension of phosphogypsum. 'the negative effect of higher temperatures on the solubility of calcium sulfate (13.08 mmol/dm(3) at 95 degrees C vs. 15.43 mmol/dm(3) at 40 degrees C) was utilized. In several repeated cycles, calcium sulfate component was progressively dissolved in water at room temperature and then precipitated at 100 degrees C, using the same liquid phase throughout the experiment. Therefore, phosphogypsum was separated into recrystallized (purified) gypsum, insoluble residue and supernatant, and the mass balance for the experiment was calculated. Elemental, XRD and SEM-EDS analyses were performed on raw phosphogypsum, purified gypsum and insoluble residue. The whiteness of raw phosphogypsum and purified gypsum were determined and compared. The main objective of the study was to investigate the nature of insoluble impurities, in order to define and optimize the methods for their removal during a potential industrial processing of phosphogypsum
Future environmental challenges of the urban protected area Great War Island (Belgrade, Serbia) based on valuation of the pollution status and ecosystem services
No full textThe Great War Island (GWI) is an area of importance for the protection of the environment, cultural and historical heritage of Belgrade, Serbia. According to the International Union for Conservation of Nature (IUCN) this area belongs to the N category - Habitats and Other Regulated Areas. The main objectives of this paper are to evaluate the potential impacts of pollution on ecosystem services of the Great War Island and to explore different scenarios for future urban development of the Great War Island that will have implication for human well-being. The aims of this paper are set up based on the evaluation of ecosystem services of the Great War Island and assessment of the pollution status of the Great War Island. In order to evaluate pollution status of the GWI inorganic and organic composition of sediments were examined. Additionally, the content of microelements was determined in the leaves of the Salix alba L. Pollution indices indicate that all investigated sampling sites are polluted and correspond to high and very high degree of contamination. Cd and Cu show high to extremely high degree of contamination while Sb has extremely high degree of contamination. Content of As, Co, Cu, Ni and Zn in leaves of Salix alba L. is in sufficient to normal range, while content of Cd is between the sufficient and excessive values generalized for various species. Typical oil distributions of terpanes and steranes and values of the corresponding maturity parameters clearly indicated that the sediments of the GWI, in addition to native organic matter, contained oil pollutants of anthropogenic origin. GWI provides provisioning, regulating, supporting and cultural ecosystem services. In relation to ecosystem services two possible scenarios can be predicted: first - losing the status of a protected area due to urbanization; and the second - increasing the degree of protection by admission into international protection lists
Zearalenone and ochratoxin a: adsorption by kaolin modified with surfactant
No full textOctadecyldimethylbenzyl ammonium chloride (OA) was used as a surfactant for the preparation of organokaolin. The natural kaolin (from a plant for production of quartz sand in Rgotina, Serbia) was modified with a surfactant in amount equal to 90% of the kaolin cation exchange capacity (CEC). FTIR spectroscopy was used for characterization of the new product. FTIR spectra confirmed the presence of OA ions at the kaolin surface. Adsorption of mycotoxins - zearalenone (ZEN) and ochratoxin A (OCHRA) was studied by organokaolin at different amounts of adsorbent and pHs. Results showed that the presence of organic cations in the kaolin structure increased adsorption of both ZEN and OCHRA. Adsorption of the mycotoxins by organokaolin increased with increasing amounts of adsorbent and, at the lowest amount of solids in suspension, adsorption of ZEN and OCHRA was slightly higher at pH 7 and 9
Elektrohemijski sintetizovani kompoziti sa inkorporiranim antibakterijskim agensima
No full textElektrohemijske metode su korišćene za sintezu različitih kompozita namenjenih za medicinsku primenu kao antibakterijske prevlake za koštane titanske implantate ili kao visoko efikasni antibakterijski hidrogelovi za ubrzano zarastanje rana. Elektroforetskim taloženjem (EPD) u jednom koraku pri konstantnom naponu, uspešno je dobijena kompozitna prevlaka na bazi hidroksiapatita (HAP), hitozana (CS) i gentamicina (Gent) iz vodene suspenzije na titanu. Sadržaj gentamicina je kvantifikovan pomoću tečne hromatografije sa ultravioletnom (UV) detekcijom. Prevlaka HAP/CS/Gent je pokazala dobru antibakterijsku aktivnost protiv Staphylococcus aureus i Escherichia coli, što ukazuje na visok potencijal za biomedicinske primene. Biokompatibilni nanokompozitni hidrogel polivinil-alkohol/hitozan/grafen (PVA/CHI/Gr) sa nanočesticama srebra (AgNPs) dobijen je in situ elektrohemijskom sintezom u matrici nabubrelih hidrogelova PVA/CHI/Gr. Otpuštanje srebra je praćeno tokom 28 dana, a dobijeni profili ukazuju na postepeno kontrolisano otpuštanje tokom ovog perioda. Antibakterijska aktivnost prema S.aureus i E.coli je potvrđena testom u suspenziji i agar-difuzionom metodom.Electrochemical methods were used for the synthesis of various composites intended for medical use as antibacterial coatings for bone titanium implants or as highly effective antibacterial hydrogels for accelerated wound healing. Electrophoretic deposition (EPD) in a single step at the constant voltage was successfully used to obtain composite coating based on hydroxyapatite (HAP), chitosan (CS) and gentamicin (Gent) from an aqueous suspension on titanium. Gentamicin content was quantified by liquid chromatography with ultraviolet (UV) detection. HAP/CS/Gent coating exhibited good antibacterial activity against Staphylococcus aureus and Escherichia coli, indicating the high potential for biomedical applications. Biocompatible poly(vinyl alcohol)/chitosan/graphene (PVA/CHI/Gr) nanocomposite hydrogel loaded with silver nanoparticles (AgNPs) was produced by in situ electrochemical synthesis in the pre-swollen PVA/CHI/Gr hydrogel matrix. Silver release was monitored for 28 days and the obtained profiles indicate slow controlled release over chosen time period. Antibacterial activity against S.aureus and E.coli was confirmed by in suspension testing and by disc-diffusion method
Possibility and efectiveness of micro-organisms in purification of waste water, laguna and waterway
No full textThe quality of life on Earth in the future will largely depend on the amount of safe water. Any use of water from numerous sources for different purposes, leads to negative changes in its physical, chemical and biological characteristics, resulting in the formation of wastewater in many forms, as industrial, communal, agricultural or rain. This type of water should be collected, and purified using efficient and economical cost-effective technology, or otherwise pose a serious environmental problem. In order to stop this trend, a large number of countries are undertaking extensive measures and invests large resources in order to stop water pollution and return pure, unpolluted water to nature. In this paper, possible biological procedures for purification of the Ada Huja Lagoon Belgrade, using microorganisms from the genus Bacillus, are presented. The Laguna Ada Huja is the recipient of all the listed types of wastewater and as such represents a serious environmental problem. The experiment was performed in laboratory controlled conditions using two different doses of microorganisms. Measurements of essential parameters (pH value, Ammonium ion, Nitrites, Nitrates, Consumption of KMnO4. Chemical consumption of oxygen, Biochemical consumption of oxygen (BPK), Total organic carbon (TOC)) were performed for 1, 15 and 60 days from wastewater treatment. It has been found that proposed technology, a mixture of heterotrophic, aerobic and optional anaerobic microorganisms produces extracellular enzymes for increased degradation of organic compounds in aforementioned environmental conditions. The use of these microorganisms leads to a decrease of the wastewater BOD/COD content, in addition, it reduces the amount of waste suspensions, reduces the filamentous bacterial reduction of the sludge population, and improves the characteristic of deposits, and therefore wastewater meets the regulated boundaries of the outflows and discharges into the watercourses
Uticaj procesne temperature na strukturne karakteristike dobijenih hidročađi
No full textPoslednjih godina sve vecu paznju privlaci fiehnika kоја omogucava konverziju otpadne biomase u cvrst ugljenicni materijal (hidročađ) velike energetskih potencijala. ovaj proces je poznat kao hidrofiermalna karbonizacija (HTC). Konverzija sirove biomase u hidročađ se odvija na umerenim temperaturama i pritiscima, а kao procesni medijum se koristi podkriticna voda, stoga se cesto ova tehnika naziva i ""mokra"" piroliza. Na strukturu dobijenog proizvoda kfjucni uticaj imaju procesni narametri kao sto su pritisak, tеmperatura, reakciono vreme, vrsta biomase i odnos biomase i vode. Na osnovu pregleda litеrаturе se može zakljuciti da temperatura ima najveci uticaj na strukturne promene dobijenih hidročađi i stoga se izdvaja kao najbitniji parametar НТС procesa. Pokazano je da povećanjem reakcione tеmрегаturе raste degradacija biomase, pri čemu se prinos, ssadržaj isparljivih materija i ререlа u dobijenim hidročađima smanjuje. Sa druge strane, sadrzaj ugljenika, toplotna moć i energetska gustina se povećavaju. Ovo ukazuje da se variranjem temperature tokom НТС postupka mogu dobiti hidročađi sa znatno poboljšanim gorivnim karakteristikama u odnosnu na polaznu sirovinu, čime se upotrebna vrednost otpadne bгomase znacajno poboljšava. U radu su po рrvi put prezentovani rezultati НТС kоnvегziје otpadne biomase supstrata za gајеnје giјivа i upoređeni sa literaturnim podacima
Influence of Mechanical Activation of a Cordierite-Based Filler on Sedimentation Stability of Lost Foam Refractory Coatings
No full textFor the development of the Lost Foam refractory coatings with controlled rheologic properties, the influence of the mechanical activation process on the cordierite-based filler's properties change was examined. First of all, the test referred to the change offiller particles' size and shape, as well as to dispersion ability and stability of the coating suspension. Cordierite was obtained by synthesis in a solid state, out of the mass consisting of kaoline, alumina, quartz, sepiolite. For characterization purposes, the following methods were used: X-ray diffraction, differential thermal analysis, SEM and optical microscopy. Mechanical activation of filler was performed in a vibrating mill. The upper boundary of the grain size was 100% -30 x 10-6 m, the times were (min): 15; 30; 60. The new composition of Lost foam refractory coatings has been developed with a change of the coating production process, as well. These newly synthesized coatings proved to be effective in terms of a positive influence on a surface quality, structural and mechanical properties of aluminium castings. Test results may be useful to have the Lost Foam refractory coatings specified together with other process parameters used for the production of castings according to this casting method