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Agroindustrial waste as an adsorbent for removing copper ions from solution
No full textZahvaljujući lakoj dostupnosti, niskoj ceni i velikoj efikasnosti, biomaterijali se sve intenzivnije ispituju kao mogući materijali za uklanjanje teških metala iz otpadnih voda. Agroindustrijski otpad je lignocelulozni materijalu čijem sastavu dominiraju celuloza, lignin i hemiceluloza, te upravo zahvaljujući prisustvu njihovih raznovrsnih funkcionalnih grupa omogućeno je vezivanje jona metala i na taj način njegovo uklanjanje iz voda. Ispitivanja, rađena na oklasku kukuruza i na košticama kajsija i breskvi (otpadna biomasa iz fabrike za preradu sokova) su pokazala da su ovi biomaterijali pogodni za uklanjanje jona bakra iz vodenog rastvora. Parametri koji su ispitivani su uticaj pH vrednosti rastvora, količina biosorbenta, veličina čestica, kontaktno vreme. Operativni uslovi pod kojima su rađeni eksperimenti su: koncentracija jona bakra C=50mg/l; odnos čvrste i tečne faze M/V=20g/l; vreme kontakta t=120 min.Due to availability, high efficiency and low costs, in last few decades, biomaterials are the in focus of research, as a potential material for removing of heavy metals from waste water. Agroindustrial waste consists of cellulose, lignin and hemicellulose. Thanks to appropriate chemical active groups within their structure they are capable of sequestering anions from aqueous solutions. Experiments showed that corn cob and fruit stones (waste biomass from Juice Factory) can be used for removal of copper ions from aqueous solutions. The influence of pH solution, effect of biosorbent granulation, effect of M/V ratio, effect of contact time on biosorption process, has been analyzed. Operation conditions were: concentration of copper ions in solutions 50 mg/l, M/V ration 20 g/l, and contact time 120 minute
The possibilities of atmospheric plasma-spraying application to obtain hydroxyapatite coatings on the stainless steel samples
No full textHidroksiapatitna (HAp) prevlaka je atmosferskim (APS) plazma-sprej postupkom naneta na metalne uzorke napravljene od 316LVM čelika, namenjenog za izradu implantata u ortopedskoj hirurgiji. Razvoj savremenih ortopedskih implantata podrazumeva da se na podlogu od bioinertnih legura nanosi bioaktivna HAp prevlaka. Sintetički HAp je hemijski sličan onom koji čini mineralnu građu kostiju i zuba. Zahvaljujući dobrim bioaktivnim svojstvima hidroksiapatitnih prevlaka moguće je obrazovanje stabilne veze između koštanog tkiva i implantata. U radu je prikazana mogućnost primene APS postupka za dobijanje stabilnih HAp prevlaka na uzorcima od nerđajućeg čelika 316LVM. Praćena je mikrostruktura i poroznost prevlake metodom optičke mikroskopije i skenirajuće elektronske mikroskopije. Ca/P odnos je određen EDS analizom.For decades, the standard metallic materials for hip implants, besides the 316LVM stainless steel, were titanium- and cobalt/chromium-based alloys. Although bioinert, due to their corrosion resistance, they are not biocompatible. Contemporary surgical implants are no longer made solely from bioinert metals anymore, but with deposited bioactive hydroxyapatite (HAp) coatings. Hydroxyapatite is chemically identical with the mineral constituent of bones and teeth, which, besides its biocompatibility, provides bioactivity as well. The HAp limitations are, however, weak tensile strength and low fatigue resistance for long term loadings, if used alone. This is the reason for HAp to be deposited onto the surgical implant, and to enable its bioactivity, which means intergrowth with bones, and therefore the long-lasting and mechanical stable non-cemented prosthesis. This is important predominantly because of the need for such prostheses for younger population and a better life quality. There are several contemporary techniques that have been used for deposition of these coatings onto the metal implant. The possibilities of atmospheric plasma-spraying for obtaining stable HAp coatings on 316LVM stainless steel, ordinarily used as a standard material for hip implants production, are presented in this paper. The coatings of a commercially available hydroxyapatite powder were plasma-sprayed onto specimens of medical grade 316LVM stainless steel under various operating conditions. Optical microscopy was used for microstructure and porosity characterization, while the coating morphology and Ca/P ratio were analyzed using an SEM equipped with EDX. The coating microstructure varied from a porous to a glassy structure, depending on the operating conditions and coating thickness. Coating porosity was determined to be at the lower required limit requested for the bone-coating intergrowth possibility, but nevertheless adhesion measurements showed good results. The Ca/P ratio was determined for both as-deposited coatings and after ageing in distilled water for various time and temperature combination
Efficient phytoremediation of uranium mine tailings by tobacco
No full textThis investigation shows that tobacco plant roots and leaves accumulate 60 times more uranium than previously reported. Phytoremediation is a convenient technique to clean up polluted soils using herbaceous plants and trees. Increasing research aims to identify novel plant species that accumulate toxic metals. Tobacco plant (Nicotiana tabacum L.) is a promising cultivar for phytoremediation because tobacco is fast growing and easily propagated. Here, we study phytoremediation of uranium by two tobacco varieties Virginia and Burley, bred in natural conditions. Plants were grown on uranium mine tailings with an average uranium content of 15.3 mg kg(-1). Each shoot sample was cross-sectioned into five uniform groups of leaves and stem segments. Results show a substantial variance in uranium uptake according to the section elderliness and origin of the plant parts. The highest concentrations of uranium values recorded in leaves of Burleys and Virginias nearest root shoot sections were 4.18 and 3.50 mg kg(-1), respectively. These values are 60 times higher rates than those previously published for leaves of cultivars grown under similar conditions. Taking into account the level of soil contamination, the content of accumulated uranium demonstrates uranium hyperaccumulatory properties of tobacco plant and its potential utilization in phytoremediation of uranium-contaminated mediums
Hg-bearing sphalerite from the Rujevac polymetallic ore deposit, Podrinje Metallogenic District, Serbia: Compositional variations and zoning
No full textRujevac is a low-temperature hydrothermal polymetallic Sb(As)-Pb-Zn vein-type ore deposit, hosted in volcanogenic-sedimentary zone situated in Rujevac-Crvene Stene-Brezovica Diabase-Chert Formation (DCF) of the Podrinje Metallogenic District (PMD), Serbia. The mineralogical composition of the deposit consists of sulfides (stibnite, sphalerite, pyrite, arsenopyrite, galena, realgar and orpiment), sulfosalts (zinkenite, plagionite, robinsonite, twinnite and gratonite), native arsenic, Sb-oxides (valentinite, senarmontite and kermesite), and gangue minerals (quartz, calcite and dolomite). Minerals containing mercury as a major element have not been detected. According to optical features, sphalerite belongs to the cleophane, low Fe content variety (yellowish to colorless). Electron Probe Micro-Analyses (EPMA) of sphalerite revealed wide compositional variations. The Hg content in sphalerite varies between 0.30 and 6.47 wt%. The range of other minor elements (Fe and Cd) is highly variable; Mn, Sn, Ge, In, Tl, and As were analyzed, but not detected. Hg-rich zones occur as narrow lamellae and are related to the crystallographic directions of sphalerite. The average values of the EPMA results gave the crystallochemical formula of this sphalerite (Zn-0.981, Fe-0.007, Cd-0.007, Hg-0.008)(Sigma 1.003)S-0.997. Strong negative correlations have been determined between Sigma Fe + Cd + Hg vs. Zn, and Hg vs. Zn, while these are absent between all other analyzed elements
Possible uses of zeolites in environmental and remediation technologies
No full textOvaj rad ukazuje na moguće pravce upotrebe prirodnih mineralnih sirovina - zeolita, u tehnologijama vezanim za zaštiti i očuvanju životne sredine. Zeoliti su tektoalumosilikati u kojima (Si,Al)4O4 tetraedri izgrađuju kostur ili skelet, stvarajući šupljine u kojima se nalaze veliki katjoni i molekuli vode, koji imaju značajan stepen pokretljivosti što dopušta katjonsku izmenjivost i reverzibilnu dehidrataciju, što je jedno od najvažnijih svojstava zeolita, na kome se i zasniva njegova višestruka primena. Ovi minerali bez prethodne modifikacije se koriste za uklanjanje metala, amonijaka i drugih katjonskih zagađivača iz vode, vazduha i zemljišta. Ispitivanja efikasnosti adsorpcije Pb, Cu, Zn iz otpadnih voda rađena su na prirodnom klinoptilolitu i klinoptilolitu prethodno prevedenom u Na-oblik. Rezultati pokazuju da je visok stepen adsorpcije Pb postignut na oba ispitana mineralna adsorbenta (99%), dok je adsorpcija Cu i Zn efikasnija na Na-klinoptilolitu, i za Cu iznosi 95%, a za Zn 96%. Zeoliti takođe mogu imati značajnu ulogu u uklanjanju amonijum jona iz kontaminiranih voda. Ispitivanja pokazuju da se umanjenje koncentracije amonijum jona kreće od oko 74% do čak 98% u zavisnosti od količine dodatog adsorbenta. U vodama u kojima je prisutan uglavnom amonijačni jon kao zagađivač, zeoliti se nakon upotrebe mogu koristiti za proizvodnju amonijačnih đubriva. Kontrolisanim procesom modifikacije organskim površinski aktivnim supstancama, dobijaju se modifikovani alumosilikatni minerali koji imaju veću efikasnost adsorpcije, kako prema slabije polarnim organskim zagađivačima, tako i prema neorganskim anjonima. Izmenjivi katjoni na površini minerala mogu biti zamenjeni velikim dugolančanim molekulima kvaternarnih amina, pri čemu se dobijaju pogodni adsorbenti za fenol, benzen, ksilen, toluen i druge organske kontaminente. Osim značajne uloge u prečišćavanju voda, u poslednje vreme se dosta govori i o upotrebi zeolita u adsorpciji gasovitih polutanata. Vršena su istraživanja uklanjanje NOx iz industrijskih gasnih tokova upotrebom zeolita aktiviranog amonijumovim jonima. Proces se zasniva na tome da joni amonijuma vezani za mikroporozne alumosilikate redukuju NOx u N2 na temperaturama manjim od 373 K u suvim uslovima. Različiti autori su uporedo ispitivali adsorpciju isparljivih organskih jedinjenja na zeolitu i aktivnom uglju, i istaknuta je prednost zeolita u odnosu na aktivni ugalj u svim aspektima osim u ceni. Na osnovu svega prikazanog, a dat je samo deo širokog spektra moguće primene ovih minerala, može se konstatovati da zeoliti zaista predstavljaju prirodne resurse izuzetnih sposobnosti, i da će dalja ispitivanja njihove upotreba doprineti održivoj budućnosti, s obzirom na trenutnu i projektovanu sliku stanja životne sredine.This article points out some possible applications and uses of natural mineral raw materials - zeolites in environmental and remediation technologies. Zeolites are tecto-alumosilicates, in which (Si, Al)4O4 thetraeders form skeleton structures with voids which large cations and water molecules can enter. Within the zeolite structure they remain highly movable which allows cation-exchange and reversible dehydratation. This is one of the main properties of zeolites on which their multiple use is based on. These minerals are often used without any prior modification for removal of metal ions, ammonia and other cationic water, soil and air pollutants. Determinations of adsorption efficiencies for Pb, Cu, Zn from wastewaters were performed with natural clinoptilolite, and modified clinoptilolite in Na-form. Results show high degree of adsorption for Pb on both analyzed mineral adsorbents (99%), while adsorption of Cu and Zn is much more efficient on Na-clinoptilolite and equals 95% for Cu and 96% for Zn. Zeolites can also have significant role in wastewater treatment for ammonia removal processes. Studies show reductions in ammonia concentration (removal efficiency) from 74 to even 98%, depending on quantity of added adsorbent. Furthermore spent adsorbent from treatment processes, where mainly ammonia is present as a pollutant, can be used for production of ammonia fertilizers. Through controlled process of modification with organic surfactants, modified alumosilicate minerals with higher adsorption affinity towards weak polar organic pollutants as well as inorganic anions are obtained. Exchangeable cations on the surface of the mineral can be substituted with large long-chained molecules of quaternary amines and efficient adsorbents for phenol, xylene, toluene, and other organic pollutants are produced. Besides significant role in wastewater treatment processes, lots of potential uses in adsorption of gaseous pollutants are investigated lately. Use of ammonia activated zeolites in NOx removal processes from industrial flue gases, is an example of such research activities. NOx is reduced to N2 on temperatures less than 373 K in dry conditions by the ammonia ions bonded to the microporous alumosilicates. Different authors have analyzed and compared adsorption of volatile organic pollutants on zeolite and charcoal. Results of these studies favor zeolite in all aspects apart from the price. With all mentioned above it is safe to say that zeolites are natural materials with outstanding properties and that further investigations of their use could be beneficial to sustainable future regarding current and projected state of the environment
Influence of active components addition to mould mixture on the castings surface
No full textOd vrste i kvaliteta kalupne mešavine odnosno njenog ponašanja u dodiru sa stopljenim metalom u realnim uslovima najviše zavise intenzitet, i uopšte razvoj, pojedinih procesa na graničnoj površini dodira metal-kalup. Značajno mesto u odigravanju procesa međusobnog delovanja livačkih kalupa i tečnog metala pored hemijskog, mineralnog sastava peska, vrste vezivnog sredstva imaju i dodaci kalupnim mešavinama. Ovi dodaci, tj aktivne komponente, uslovljavaju određene promene na povišenim temperaturama u samoj mešavini kao i njeno reagovanje sa površinskim slojem tečnog metala. Cilj ispitivanja je bio da se vidi u kolikoj meri sastav kalupne mešavine sa i bez dodatih-aktivnih komponenata utiče na površinu odlivaka.The intensity, and overall development of individual process on the metal-mould interface depend on the type and quality of mould mixture or its behavior in contact with the melted metal in real conditions. Important role in interaction between foundry moulds and liquid metals, in addition to chemical and mineral composition of sand, and a type of binding material, play also additives for mould mixtures. These additives, i.e. active components, provided some changes at elevated temperatures inside the mixture, as well as its reaction with the surface layer of liquid metal. The aim of this investigation was to determine how the composition of the mould mixture with and without active components affect the surface of castings
Mechanical activation of talc in high-energy speed rotary mechanoactivator
No full textThis paper presents the results of research on mechanical activation of raw talc in a high-energy speed rotary mechanoactivator. The results of research on effect of mechanically activated talc on the degree of recovery Fe2O3 by hydrometallurgical method are also presented. The process and mechanism of mechanical activation in this type of mechanoactivator were achieved by impact. The variable parameters of the inechanoactivator operation were: rate of rotor revolutions (n(0) = 10,000 and n(0) = 20,000 rpm), circle sieve mesh (80, 120, 200 and 500 mu m) and the current intensity. The following parameters of the dry mechanical activation process were studied: mechanical activation time, rotor speed, mechanoactivator capacity and specific energy consumption. The mechanically activated powder was examined by application of differential thermal and thermogravimetric analyses, analysis of the degree of mechanical activation and the specific surface area as well. According to the obtained results, the highest rate of mechanical activation was obtained with a nominal mechanoactivator load. The degree of mechanical activation increases with increasing the rate of rotor revolution, circle sieve mesh size and with the increasing mechanoactivator load. It was shown that high-grade talc concentrate with low content of Fe2O3 can be obtained by physical-chemical process. A new approach for obtaining high-grade talc concentrate was achieved trough mechanically activated talc effect on the degree of recovery of Fe2O3 by hydrometallurgical process
A step toward the novel environmental friendly fertilizer
No full textFosfatna ruda se danas u Evropi i svetu svrstava u red strateških sirovina i prirodni resurs u značajnom deficitu. Srbija se takođe poslednjih godina suočava sa ozbiljnim problemima u oblasti smanjenja proizvodnih kapaciteta mineralnih đubriva, njihove potrošnje i primene, kao i odsustva precizne zakonske regulative u pogledu njihovog kvaliteta. Sve gore napomenuto rezultiralo je smanjenjem prinosa i kvaliteta gajenih kultura i odsustva konkurentnosti u izvozu. Upotreba prirodnih fosfata kao mineralnih đubriva je poznata u praksi kao ekonomski isplativija i ekološki podobnija nego primena industrijskih fosfornih đubriva ali sa ograničenom primenom isključivo na kiselim tipovima zemljišta. Naše istraživanje bazira se na dizajniranju funkcionalnog materijala nastalog u sinergističkoj sprezi zeolita sa sirovim fosfatom koji treba da doprinese većoj mobilnosti fosfatnih jona, u svim zemljišnim uslovima i širokom opsegu pH. U tu svrhu ispitivan je uticaj zeolita i zeolita modifikovanog amonijumovim jonom na rastvorljivost prirodnog fosfata, apatita. Utvrdili smo da prisustvo zeolita povećava rastvorljivost apatita. Površinska modifikacija zeolita amonijum sulfatom dodatno uvećava konduktivnost dobijenog rastvora i podstiče fosfomobilizaciju. Dobijeni rezultati govore u prilog upotrebe modifikovanog zeolita kao aditiva prirodnoj fosfatnoj rudi u cilju povećenja njene rastvorljivosti i efikasnije primene.Nowadays worldwide, phosphate ores ranked as one of the strategically most important raw materials and a natural resource in a significant deficit. Recently, Serbia also faced with serious problems of reducing production capacities of mineral fertilizers, their decreased consumption and application and the lack of precise legislation in terms of its quality. All of the above mentioned, resulted in reducing yields and cultivated crops quality and the absence of competitiveness in exports. Using natural phosphate fertilizers is from previously known as an economically profitable and ecologically more suited than the application of industrial phosphorus fertilizers, but limited solely to the acidic types of soil. Results of our experiment indicate that the presence of zeolite increases the solubility of phosphate ore in various soil conditions and a wide pH range. The addition of zeolites to the rock phosphate in a solution facilitate release of phosphorus in the first 24 h for about 60%. Furthermore, addition of modified NH4-zeolite notably increases conductivity of obtained solutions and promotes release of P for about 150%, for the same time. Obtained results speak in favor of use NH4- zeolite as an additive to the phosphate ore with the aim to reach its higher solubility and efficient implementation
Lithotamnian limestone from the deposit 'Dobrilovići' in flue gas desulphurization by wet process
No full textU ovom radu su dati rezultati ispitivanja litotamnijskog krečnjaka iz ležišta 'Dobrilovići', za upotrebu u odsumporavanju dimnih gasova mokrim postupkom. Prema uslovima tehnološkog postupka, ODG krečnjak treba da ispuni određene kriterijume da bi mogao da se koristi u tu svrhu. Imajući u vidu te kriterijume, u ovom radu su ispitivani hemijski sastav, nasipna masa, granulometrijski sastav i Bondov radni indeks. Rezultati ovih ispitivanja su pokazali da krečnjak ležišta 'Dobrilovići' prema svojim fizičko-hemijskim karakteristikama potpuno odgovara za upotrebu u procesu odsumporavanja dimnih gasova u termoelektranama, kao i za dobijanje praškastog (rasutog) gipsa.This paper presents the results of investigation lithotamnian limestone from the 'Dobrilovići' deposit for the use in flue gas desulphurization by wet process. According to the technological process conditions, FGD limestone should fulfill the certain criteria in order to be used for that purpose. In respect to those criteria, this paper investigates the chemical composition, bulk density, grain-size distribution and Bond work index (kWh/t). The results of these investigations have showed that limestone from 'Dobrilovići' deposits, according to its physicochemical properties, is completely suitable for the flue gas desulphurization process in thermal power plants, as well as for disposable gypsum obtaining
Investigation the possibility of application the microorganisms in copper recovery from waste mineral materials
No full textMikrobiološko luženje predstavlja u svetu priznat metod za izdvajanja korisnih komponenti iz siromašnih ruda i sekundarnih sirovina. Prednost mikrobiološkog luženja mineralnih sirovina predstavlja malo ulaganje, odnosno ekonomska opravdanostog luženja, vrlo jednostavna primena i pogodnost ovakvog luženja sa aspekta zaštite životne sredine. U ovom radu je ispitivanja mogućnost mikrobiološkog luženje bakra iz jalovine (raskrivke starog kopa u Boru) u laboratorijskim uslovima, korišćenjem kulture Acidithiobacillus ferrooxidans. Izveden je eksperiment luženja u erlenmajerima uz mućkanje. Eksperiment je trajao tri nedelje, na prosečnoj temperaturi od 280C. Procenat izluženog bakra na kraju eksperimenta je iznosio 34%. Dobijeni rezultati bi trebalo da posluže kao osnova za ponovno uvođenje ove, u svetu prihvaćene tehnologije u eksploataciji mineralnih sirovina, u cilju dobijanja korisnih komponenata iz siromašnih ruda kao i za remedijaciju kontaminiranog zemljišta.Microbiological leaching is a widely accepted method for the extraction of useful components from low-grade ores and secondary mineral row materials. The main advantages of this process are low investment, simple operation and its environmentally friendly property. The object of this paper was to examine the possibility of microbiological leaching of copper from ore dump by Acidithiobacillus ferrooxidans. Leaching experiments were performed by the shake flask testing technique at 280C, during three-week period. The percentage of the copper leached at the end of this experiment was 34 %. The obtained results should serve as a basis for reuse this widely accepted technology for exploitation of mineral row materials in order to obtain useful components from poor ores, as well as for the remediation of contaminated soils