ELECTRODEPOSITED, Ni-BASED, NON-NOBLE METAL COATINGS AS CATHODES FOR HYDROGEN EVOLUTION IN CHLOR-ALKALI ELECTROLYSIS
Vladimir Jović1, Uroš Č. Lačnjevac1, Borka M. Jović1, Nedeljko V. Krstajić2
1University of Belgrade, Institute for Multidisciplinary Research, Belgrade, 2University of Belgrade, Faculty of Technology and Metallurgy, Belgrade, Serbia
ABSRACT
The hydrogen evolution reaction (HER) has been investigated on two types of electrodeposited, Ni-based, non-noble metal coatings: composite coatings with inclusion of MoO 2 particles and electrodeposited NiSn alloy coatings, in order to find suitable replacement for noble metal coatings (commercial De Nora’s Ni-RuO 2 electrode (DN)), as cathodes for industrial application in the zero-gap membrane cell for chlor-alkali electrolysis. Some samples of both types of cathodes showed better catalytic activity for the HER than the DN electrode under the conditions of industrial applications: 32 mass % NaOH at 90 o C and j = -0.3 A cm -2 . Since lower overvoltage for the HER is not the only criteria for successful application in industrial electrolysis, service life test (SLT), simulating long time operation of cathodes, has been applied for both types of cathodes. It has also been shown that certain samples of both types of cathodes could be promising replacement for the commercial DN electrode since they showed better performance during the SLT.
Keywords: Hydrogen evolution, Ni-MoO 2 composite coatings, NiSn ally coatings, service life test
ELEKTROHEMIJSKI ISTALOŽENE PREVLAKE NA BAZI Ni I NEPLEMENITIH METALA
KAO KATODE ZA IZDVAJANJE VODONIKA U HLOR-ALKALNOJ ELEKTROLIZI
IZVOD
Reakcija izdvajanja vodonika ispitivana je na dva tipa prevlaka od neplemenitih metala dobijenih elektrohemijskim taloženjem: kompozitne prevlake sa uključkom MoO 2 čestica i prevlake od NiSn legura. Cilj rada je bio dobijanje katoda koje bi mogle da zamene postojeće katode na bazi plemenitih metala (komercijalne Ni-RuO 2 katode, proizvođač De Nora Industrija) u industrijskom procesu hlor-alkalne elektrolize. Neki uzorci oba tipa katoda pokazali su bolju katalitičku aktivnost za reakciju izdvajanja vodonika od komercijalne katode u uslovima industrijske primene: 32 mas. % NaOH, 90 o C i j = -0.3 A cm -2 .
Imajući u vidu da bolja katalitička aktivnost za reakciju izdvajanja vodonika nije jedini kriterijum za uspešnu primenu u industrijskoj elektrolizi, ispitivan je vek trajanja oba tipa katoda, definisan određenom procedurom. Pokazano je takođe da neki uzorci oba tipa katoda mogu naći primenu u industrijskom postupku hlor-alkalne elektrolize, jer su pokazali bolje osobine od komercijalne katode pri ispitivanju veka trajanja katoda.
Ključne reči: izdvajanje vodonika, kompozitne Ni-MoO 2 prevlake, prevlake od NiSn legura, vek trajanja katoda
Organoclay-Polymer Nanocomposites
Darko LJubic1, Marina Stamenovic2, Chad Smithson1,
Maja Nujkic3, Jelena Petrovic4, Slavisa Putic4
1McMaster University, Department of Chemical Engineering,
Hamilton, ON, Canada, 2College of Vocational Studies Belgrade Polytechnic,
Belgrade, Serbia, 3University of Belgrade, Technical Faculty in Bor,
Bor, Serbia, 4University of Belgrade, Faculty of Technology and
Metallurgy, Belgrade, Serbia
ABSTRACT
The properties of polymer nanocomposites exceed the properties of common composite materials due to the nanoscale size and morphology of the fillers used.Particulate fillersare commonly used in polymers forimproved mechanical and thermal properties, as well as modified electrical properties and cost reduction. Organically modified layered clays,such asmontmorillonite, are among the most widely used fillers for the improvement of polymer matrices. Presented in this review are some of the most studied clay nanocomposites including clay-polyolefin, clay-polyester and clay-thermoplastic polyurethanenanocomposites. Additionally, the properties of clay-biopolymers nanocomposites will also be discussed.
Key words: organically modified clays, montmorillonite, polymers,nanocomposites, properties
ORGANOGLINA – POLIMERNI NANOKOMPOZITI
IZVOD
Svojstva polimernih nanokompozita prevazilaze svojstva uobičajenih kompozitnih materijala zbog nano-dimenzija i morfologije upotrebljenih punioca. Čestični punioci se uglavnom koriste u cilju poboljšnja mehaničkih i toplotnih svojstava polimera, kao i za modifikovanje električnih svojstava polimerne matrice i smanjenja cene koštanja. Organski modifikovane slojevite gline, kao što je montmorilonit, su između ostalih, najzastupljeniji punioci u upotrebi za poboljšanje svojstava polimernih matrica. Ovim preglednim radom biće prikazani najznačajniji i najviše proučavani glina-polimerni nanokompoziti, kao što su glina-poliolefini, glina-poliestar i glina-termoplastični poliuretan nanokompoziti. Takođe, svojstva biopolimer-glina nanokompozita biće predstavljena i razmatrana u radu.
Ključne reči: organski modifikovane gline, montmorilonit, polimeri, nanokompoziti, svojstva
RENEWABLE ENERGY RESOURCES IN SERBIA AND RUSSIA
Larisa Jovanovic1, Vadim Ermakov2, Zoran Čajka3
1ALFA University, Belgrade, Serbia, 2V.I. Vernadsky Institute of Geochemistry and Analytical Chemistry of the Russian Academy of
Sciences, Moscow, Russia, 3Singidunum University, FEFA, Belgrade, Serbia
ABSTRACT
Energy Policy of the Republic of Serbia and Russia is entirely based on the principles of sustainable development and the Kyoto Protocol. This paper reviews in details the characteristics of energy policy in Serbia and Russia and provides examples of certain kinds of energy. Serbia and Russia are rich in renewable energy resources.The explorations of mineral and thermal mineral water sources carried out in Serbia have shown high quality mineral waters that can be used for medical purposes. Mineral and thermal mineral sources in health resorts, in Serbia, represent natural resources with large possibilities for the development of tourism, health tourism, agriculture and other economic activities. Special attention should be directed to the needed multidisciplinary research projects for the purpose of the relevant criteria necessary for usage of every thermal mineral water. Intensive exploitation of the renewable resources must become one of the important aims of economic development in Serbia.
Keywords: renewable energy sources, biomass, biofuel, wind energy, tidal energy, geothermal energy, Republic of Serbia, Russian Federation
OBNOVLJIVI ENERGETSKI RESURSI U SRBIJI I RUSIJI
IZVOD
Energetska politika Republike Srbije i Ruske Federacije je u potpunosti zasnovana na principima održivog razvoja i Kjoto protokola. Ovaj rad analizira specifičnosti energetske politike u Srbiji i Rusiji i daje primere određenih vrsta energija. Srbija i Rusija bogate su obnovljivim energetskim resursima. Istraživanja mineralnih i termomineralnih voda sprovedena u Srbiji pokazuju visok kvalitet mineralnih voda koje su mogu primeniti u medicinske svrhe. Mineralni i termomineralni banjski izvori u Srbiji predstavljaju prirodne resurse sa velikim mogućnostima u razvoju turizma, poljoprivrede i ekonomije. Posebna pažnja mora se usmeriti na multidiscciplinarna istraživanja u cilju prikupljanja relevantnih podataka potrebnih za upotrebu svake vrste termomineralnih voda. Intenzivna eksploatacija obnovljivih resursa mora postati jedan od važnih ciljeva privrednog razvoja Srbije.
Ključne reči: izvori obnovljive energije, biomasa, biogorivo, energija vetra, energija vode, geotermalna energija, Republika Srbija, Ruska Federacija.
OPTICAL PROPERTIES OF GOLD ALLOY 585 MONITORED THROUGH AMPLITUDE DIMINUTIONS AT ANNEALED AND COLD ROLLED STRIPS WITH LOW DEFORMATIONS
Radiša Perić1 , Zoran Karastojković2, Milan Jovanović3, Milesa Srećković4, Zoran Janjušević5, Radosav Gajić3
1Perić&Perić, d.o.o., Požarevac, 2Technical Colege, Bеlgarde,
3University of Belgrade,Institute for Physics, Zemun-Belgrade, 4University
of Belgrade,Electrotechnical Faculty, Beograd,
5Institute of Nuclear and Other Mineral Raw Materials, Bеоgrad, Serbia
ABSTRACT
The optical properties are determined and presented in an adequate references for common pure noble metals (Au, Ag, Cu, etc.) but not for almost their alloys. This was a reason for investigation of specific optical properties amplitude diminutions at gold alloy of 585 finess, as an often used alloy in jewelry. This alloy for jewel making in practice usually is composed from three – or four metals. The jewels, as their nature need, ordinary must possess pretty high level of brilliance. Variuos metals will produce changes in optical properties of an alloy, indeed. Here are represented some ellipsometric measuring of tg(ψ) for annealed and cold rolled strips from golden alloy 585. Cold rolling is provided by height reduction of 10, 20 and 30%. Typical microstructures at annealed and cold rolled (30%) deformation were shown.
Key words: 585 gold alloy, ellipsometry, tg(ψ) values, microstructures of strips
OPTIČKE OSOBINE LEGURE ZLATA 585 PRAĆENE KROZ SKRAĆENJE AMPLITUDE U ŽARENIM I HLADNO VALJANIM TRAKAMA SA MALIM DEFORMACIJAMA
IZVOD
Optičke osobine su određene i prisutne u odgovarajućoj literaturi za uobičajene čiste plemenite metale (Au, Ag, Cu i dr.) ali ne i za većinu njihovih legura. To je bio razlog za ispitivanjem specifičnih optičkih osobina kao kašwewe amplitude u leguri zlata finoće 585, kao jedne često korišćene legure u zlatarstvu. Ova legura za izradu nakita u praksi se izrađuje sa tri- ili četiri metala.
Nakit, kako to njegova priroda zahteva, obično mora da poseduje prilično visok nivo sjajnosti. Različiti metali će, svakako, proizvesti promene u optičkim osobinama legure. Za praćenje ovih osobina su izvršena merenja pomeranja amplitude tg(ψ) svetlosti u opsegu talasnih dužina 300-800nm. Ovde su predstavljena neka elipsometrijska merenja tg(ψ) za odžarene i hladno valjane trake od legure zlata 585. Hladno valjane trake su izvedene sa redukcijama 10, 20 i 30%. Prikazane su tipične mikrostrukture za žareno i hladnovaljano stanje.
Ključne reči: legura zlata 585, elipsometrija, vrednosti tg(ψ), mikrostruktura traka
SUKCESIVNA APSORPCIJA I REFRAKCIJA KOD ULTRATANKIH MOLEKULSKIH NANOFILMOVA
Dragana Rodić1, Blanka Škipina2, Jovan P. Šetrajčić1
1Univerzitet u Novom Sadu, Prirodno-matematički fakultet, Departman za fiziku, Novi Sad, Srbija, 2Univerzitet u Banja Luci, Tehnološki
fakultet, Banja Luka, Republika Srpska – BiH
IZVOD
U radu su na osnovu formiranog modela nanofilm kristalnih struktura teorijski istraživane i izučavane promjene optičkih osobina usled prisustva granica kod simetričnih ultratankih filmova. Ispitani su uticaji pet graničnih parametara na pojavu lokalizovanih eksitonskih stanja, kao i na njihovu povezanost sa efektima diskretizacije i selekcije rezonantne apsorpcije prisutnog elektromagnetnog zračenja. Analitičko-numeričkim proračunom, nađen je energetski spektar eksitona i njihova prostorna distribucija duž ose ograničenja (po slojevima). Određena je relativna permitivnost ovih ultratankih dielektričnih filmova i analiziran uticaj graničnih parametara na pojavu diskretne, tj. selektivne apsorpcije.
Ključne riječi: nanofilm, eksitoni, permitivnost, apsorpcija.
SUCCESSIVE ABSORPTION AND REFRACTION
OF ULTRATHIN MOLECULAR NANO-FILMS
ABSTRACT
Based on the formed model of nanofilm crystal structures, changes of optical properties due to the presence of borders for the case of symmetrical ultrathin films are theoretically investigated in this paper. Influence of five border parameters on the occurrence of localized exciton states is examined, as well as their relation with the effects of discretization and selection of resonant absorption of present electromagnetic radiation. Used combined analytical-numerical calculation to find the allowed energy states of excitons and their spatial distribution (per layers) along the axis perpendicular to surface planes. We determined permittivity for the observed models of these ultrathin dielectric films and explored the influence of boundary parameters on the occurrence of discrete and selective absorption.
Key words: nano-films, excitons, permittivity, absorption.
MULTIVARIJANTNA STATISTIČKA ANALIZA PARAMETARA KVALITETA
POVRŠINSKIH VODA U VOJVODINI
Borko Matijević, Đenđi Vaštag, Milena Bečelić-Tomin,
Suzana Apostolov, Božo Dalmacija
Univerzitet u Novom Sadu, Prirodno-matematički fakultet, Departman za hemiju, biohemiju i zaštitu životne sredine, Novi Sad, Srbija
IZVOD
Praćenje hemijskih i fizičko-hemijskih parametara (monitoring) površinskih voda predstavlja veoma značajan faktor u kontroli kvaliteta i upravljanju vodama. Kvalitet površinskih voda uglavnom je određen atmosferskim uticajem (prirodni proces) i ispuštanjem industrijskih i komunalnih otpadnih voda u vodna tela (antropogeni proces). Primenom različitih statističkih metoda (multivarijalna statistička analiza) može se u znatnoj meri redukovati obimnost raspoloživih podataka dobijenih monitoringom, a samim tim i ispravna interpretacija dobijenih rezultata o kvalitetu i ekološkom statusu voda. U ovom radu su primenom multivarijalne statističke analize (klaster analiza, faktor analiza i analiza glavnih komponenti) obrađeni rezultati analiza površinskih voda na teritoriji AP Vojvodine u toku 2011. godine. Na osnovu dobijenih rezultata statističke analize mogu se identifikovati glavni faktori koji imaju uticaj na ekološki status i ekološki potencijal vodnih tela i unaprediti postojeća mreža monitoringa.
Ključne reči: kvalitet voda, klaster analiza, analiza glavnih komponenti, faktor analiza
MULTIVARIATE STATISTICAL ANALYSIS OF PARAMETERS OF SURFACE WATER QUALITY IN VOJVODINA
ABSTRACT
Monitoring of chemical and physical-chemical parameters of surface water is a very important factor in the quality control and management. Surface water quality is largely determined by atmospherics (natural process) and the discharge of industrial and municipal waste water (anthropogenic process). By applying different statistical methods (multivariate statistical analysis) can significantly reduce the bulkiness of the available data obtained by monitoring, and therefore the correct interpretation of the results of the quality and the ecological status of water. In this paper, using multivariate statistical analysis (cluster analysis, factor analysis and principal components analysis) processed the results of the analysis of surface water in AP Vojvodina during the 2011 year. Based on the results of statistical analysis it could by identified the main factors that have an impact on the ecological status and ecological potential of water flows. In this way it can improve the existing monitoring network.
Key words: Water quality, Cluster analysis, Principal components analysis, Factor analysis
THE IMPACT OF SURFACE PREPARATION OF WOOD ON THE ADHESION OF CERTAIN TYPES OF COATINGS
Milan Jaić1, Tanja Palija1, Milan Đorđević2
1University of Belgrade, Faculty of Forestry, Belgrade, Serbia,
2Odincovskij lakokrasochnij zavod, Helios group, Odincovo, Russia
ABSTRACT
In order to achieve an enhancement of adhesion of specific type of coating to the surface of beech wood (Fagus Sylvatica L.), the optimum substrate preparation system was determined regarding the specific coating formulation. The results showed that lower values of surface roughness parameters can be obtained by the sanding process than by the planning process. These lower values of surface roughness enable higher adhesion of a 2K acrylic-isocyanate coating. In cases where coating is performed with a 1K waterborne coating, higher values of adhesion were observed on the surfaces with higher surface roughness. Direct correlation between surface roughness and adhesion of a 2K polyurethane coating was not found. The adhesion between a 1K waterborne coating and the wood substrate is primarily based on a mechanical bonding (entanglement), while the adhesion of a 2K acrylic-isocyanate coating is primarily based on the other bonding mechanisms.
Keywords: Fagus Sylvatica L., sanding, planing, surface roughness, coating formulation, adhesion
UTICAJ POSTUPKA PRIPREME POVRŠINE DRVETA NA ADHEZIJU ODREĐENIH
VRSTA PREMAZA
porastom adhezije 2K akril – izocijanatog premaza. Kada je lakiranje vršeno primenom 1K vodorazredivog premaza, više vrednosti adhezije su zabeležene na površinama sa većom hrapavosti podloge. Direktna veza između hrapavosti podloge i adhezije 2K poliuretanskog premaza nije pronađena. Mehanizam adhezije između 1K vodorazredivog premaza i podloge drveta je prvenstveno zasnovan na mehaničkom vezivanju, dok je adhezija 2K akril – izocijanatog premaza i drveta zasnovana na drugim mehanizmima vezivanja.
MAGNETIC BEHAVIOUR OF HYBRID MAGNETIC COMPOSITE MATERIALS
Jasna Stajić-Trošić1, Aleksandar Grujić1, Mirko Z. Stijepović1,2,
Dragutin Nedeljković1, Aleksandar Stajčić1, Tomáš Žák3
1University of Belgrade, Institute of Chemistry, Technology
and Metallurgy, Belgrade, Serbia, 2University at Qatar, Department of Chemical
Engineering, Texas A&M, Doha, Qatar, 3Institute of Physics
of Materials AS CR, Brno, Czech Republic
ABSTRACT
Polymer bonded magnets are contemporary materials with a very large range of applications. The objective of this study is to assess how different content of Nd-Fe-B and/or barium ferrite particles affect on magnetic and morphological properties of bonded composite materials. Interactions between employed magnetic powders and interactions between magnetic powders and polymer binder are considered. For examination of the magnetic behavior Vibrating Sample Magnetometer (VSM) is used. Different shape and size of obtained hysteresis loops are used for comparison and prediction of polymer bonded materials properties.
Keywords: bonded magnets, Nd-Fe-B, composite materials, VSM
MAGNETNO PONAŠANJE HIBRIDNIH MAGNETNIH KOMPOZITNIH MATERIJALA
IZVOD
Polimerom vezani magneti predstavljaju savremene materijale sa veoma širokim spektrom primene. Cilj ovog rada je da se analizira i prikaže kako različiti udeli čestica Nd-Fe-B i/ili barijum ferita utiču na magnetna i morfološka svojstva bonded kompozitnih materijala. Razmatrane su interakcije između primenjenih magnetnih prahova različitog tipa i interakcije između magnetnih prahova i polimerne matrice. Za merenje magnetnih svojstava kompozita korišćen je vibracioni magnetometar (VSM). Različiti oblici i veličine dobijenih histerezisnih petlji su poređeni i analizirani u cilju predviđanja magnetnog ponašanja kompozita.
Ključne reči: Bonded magneti, Nd-Fe-B, Kompozitni materijali, VSM
KORELACIONO-REGRESIONA ANALIZA MODELIRANE PROSTORNE RASPODELE REZIDUALA HLORA U VODOVODNOJ MREŽI
Željka Ostojić1, Dušan Prodanović2, Sanja Marčetić1
1Hidroprojekat saobraćaj, Beograd, 2Univerziteta u Beogradu, Građevinski fakultet , Beograd, Srbija
IZVOD
Rezidual hlora tj. koncentracija slobodnog hlora sposobnog da vrši dezinfekciju u pitkoj vodi je važan parametar kvaliteta pitke vode, koji govori prvenstveno o njenoj bakteriološkoj ispravnosti. Sa druge strane, prisustvo slobodnog hlora je preduslov za formiranje trihalometana (THM-a). Sa ovog stanovišta razumljiv je zahtev o kvalitetu isporučene vode da ona treba da bude minimalno hlorisana, a bezbedna za piće. Prema brojnim rezultatima modeliranja i eksperimentalnih istraživanja u distributivnim mrežama, prostorna raspodela reziduala hlora je u tesnoj korelaciji sa dinamikom potrošnje, temperaturom vode, početnom dozom hlora i sadržajem organske materije u vodi. U radu su prikazani neki od načina za predviđanje sadržaja reziduala hlora i THM-a u vodovodnim mrežama. Posebna pažnja je posvećena njihovoj prostornoj promenljivosti u slučaju promene početne koncentracije hlora. Za izvođenje računskog primera je korišćen EPANET i postojeća vodovodna mreža naselja Petrovac na Mlavi.
Ključne reči: kvalitet isporučene vode,rezidual hlora, trihalometani
CORRELATION-REGRESSION ANALYSIS OF MODELLED CHLORINE RESIDUAL’S SPATIAL VARIABILITY IN WATER SUPPLY NETWORK
ABSTRACT
Residual chlorine ex. concentration of free chlorine disinfection able to carry disinfection in drinking water is an important parameter of drinking water, primarily talking about its bacteriological safety. On the other hand, the presence of free chlorine is a prerequisite for the Trihalomethane’s (THM) formation. From this point of view the water quality request for minimum chlorinated and safe potable water is understandable. In numerable modeling and experimental research the spatial diversity of chlorine residual was found to correlate with the daily consumption schedule, the water temperature, the initial dose of chlorine and organic matter content in the water. This paper presents some of the possibilities in predicting the content of residual chlorine and THM in water distribution networks. Special attention is paid to the spatial variability of residual chlorine and THM’s to a change in the initial concentration of chlorine. Results are presented using existing water supplying network of the settlement Petrovac na Mlavi using EPANET simulation software.
Keywords: quality of delivered water, residual chlorine, trihalomethanes
EFFICIENT USE OF ENERGY AND RESOURCE THROUGH CONSERVATION AND RECOVERY IN BREWERIES
Luljeta Xhagolli, Jozefita Marku
1University of Tirana, Faculty of Natural Sciences, Department of Industrial Chemistry, Tirana, Albania
ABSTRACT
Breweries are relatively large scale plants and highly energy consuming industry. Basically, beer production is divided to three processes, Brewing, Fermentation and Packaging. Brewing requires high heat consumption, particularly the wort kettle consumes one third (1/3) of steam consumption of entire plant. Fermentation with maturation process consumes large cooling energy by refrigeration system. This process consumes 60 to 70% of entire cooling capacity. Packaging process also consumes a lot of heat energy (steam). In general, steam consumption of packaging process is 70 to 80% compared to brewing process for steam consumption.
Efficient use of energy consist on conservation and recovery. Energy conservation, reduce the amount of pollution created in the production or use of energy (e.g., CO2, NOX, SO2, ash, etc.). From the other hand pollution prevention measures reduce the energy requirements for waste handling and treatment, as a result a reduction in energy consumption is an important consideration in lowering the operational cost.
There are several methods of energy recovery that can be considered by breweries to reduce energy consumption; however, most are expensive and should only be considered once measures for reducing energy consumption have been made first. The recovery of vapors condensate represent a major saving in energy consumption for a brewery. Utilization of CO2 and NH3 energy during transformation from liquid in gaseous form, is also a well known procedure in water cooling for compressors towers.
Key Words: Energy, conservation, recovery, synergy, heat, steam, cooling energy.
EFIKASNO KORIŠĆENJE ENERGIJE I RESURSA KROZ OČUVANJE
I OPORAVAK U PIVARAMA
IZVOD
Pivare su zgrade relativno velikih razmera i visoko energetski potrošači u industrija. U suštini, proizvodnja piva je podeljena na tri procesa: vrenje, fermentacija i pakovanje. Vrenje piva zahteva veliku potrošnju toplote, naročito za zagrevanje vode troši se trećina (1/3) potrošnje celog postrojenja. Fermentacija sa procesom sazrevanja troši veliku energiju za hlađenje rashladnog sistema. Ovaj proces troši 60 do 70% od celokupnog kapaciteta hlađenja. U procesu pakovanja, takođe, troši se mnogo toplotne energije (pare). U principu, potrošnja pare u procesu pakovanja je 70 do 80% u odnosu na potrošnju pare u procesu vrenja.
Efikasno korišćenje energije sastoji se u konzervaciji i oporavku. Očuvanje energije, kroz smanjenje količine zagađenja, kreiran je u proizvodnji ili korišćenju energije (npr., CO2, NOk, SO2, pepela,itd).
Od drugih mera zaštite za smanjenje energetskih potreba, rukovanje i tretman otpadom igraju važan faktor u smanjivanju operativnih troškova u proizvodnji.
Postoji nekoliko metoda za dobijanje energija koje se mogu koristiti u pivarama za smanjenje potrošnje energije; međutim, većina ovih metoda za dobijanje energija su skupi i treba posmatrati samo one koji dovode do smanjenja potrošnje energije. Oporavak isparenja kondenzata predstavlja veliku uštedu u potrošnji energije za pivare. Korišćenje energije tokom transformacije CO2 i NH3 iz tečnosti u gasovitom obliku kompresorskim kulama je, takođe, dobro poznat postupak.
Ključne reči: energija, konzervacija, oporavak, sinergija, toplota, para, energija za hlađenje.
ELEKTROKRISTALIZACIJA DENDRITA SREBRA
Evica R. Ivanović1, Nebojša D. Nikolić2
1Univerzitet u Beogradu, Poljoprivredni fakultet, Beograd-Zemun, 2Univerzitet u
Beogradu, IHTM-Institut za elektrohemiju, Beograd, Srbija
IZVOD
Morfologija elektrohemijski istaloženih dendrita srebra analizirana je tehnikom skenirajuće elektronske mikroskopije (SEM). Na osnovu morfoloških proučavanja predložena je struktura i mehanizam rasta dendrita. Dendrit srebra je dvojnikovani kristal sa {11} ravni dvojnikovanja i pravcima rasta <112>. Mehanizam rasta predstavlja kombinaciju tri procesa: a) rast ravni dvojnikovanja preko sistema uvučenih ivica, b) klizanje ravni dvojnikovanja i c) rast slojeva na završnim (111) pljosnima.
Ključne reči: dendrit, srebro, elektrohemijsko taloženje, skenirajuća elektronska mikroskopija (SEM)
ELECTROCRYStALLIZATION OF SILVER DENDRITES
ABSTRACT
Morphology of electrodeposited silver dendrites was investigated by scanning electron microscope (SEM). On the basis of morphological analysis, the structures and mechanism of growth were proposed. Silver dendrite is twin crystal with {111} twinning plane and direction of growth <112>. Mechanism of growth represents combinations of three steps: a) growth by propagation of twin planes, b) slip of twin planes and c) layer growth on the final (111) faces.
Key words: dendrite, silver, electrodeposition, scanning electron microscope (SEM)
PHOSPHOMONOESTERASE ACTIVITY UNDER DIFFERENT
MICROBIOLOGICAL SOIL PROPERTIES
Snežana Đorđević1, Dragana Stanojević2, Željko Dolijanović1,
Snežana Oljača1, Violeta Mandić3
1University of Belgrade,Faculty of Agriculture, Zemun-Belgrade, Serbia,
2Biounik d.o.o., Research and Development Center,
Šimanovci-Belgrade, 3Department of Ecology and Animal
feed, Institute for Animal Husbandry, Belgrade-Zemun, Serbia
ABSTRACT
In the present work, effects of microbiological soil properties and phosphomonoesterase activity are presented. The abundances of ammonificators, fungi, actinomycetes, Azotobacter sp., cellulolytic microorganisms, microorganisms that solubilize organic and inorganic P compounds bound to Al, Fe and Ca, have been determined by the dilution method with application of selective nutrient mediums. The first five axes explaines 86% of the total variance. The first axis explains 34.6% of variance and it appears to reflect the processes of microbiological mineralization and immobilization of phosphorus. The second axis explains 25.9% of variance and reflects microbial activity and organic matter accumulation, N biomasses, Azotobacter sp. abundance and acid and alkaline PME activities. Phosphomonoesterase activity in soil depend primarily on soil organic matter and biological factors and can be used as a parameter of plants` uptake of phosphorus, especially in conditions of its low concentration in soil.
Key words: microorganisms, soil, microbial biomass
AKTIVNOST FOSFOMONOESTERAZE U ZAVISNOSTI OD MIKROBIOLOŠKIH SVOJSTAVA ZEMLJIŠTA
IZVOD
U ovom radu ispitivan je uticaj mikrobioloskih svojstava zemljista i aktivnosti fosfomonoestreaze. Brojnost azotofiksatora, gljiva, aktinomiceta, Azotobacter sp., celulolitičkih mikroorganizama, mikroorganizma koji razlazu organske i neorganske jedinjenja vezana za P, Al, Fe i Ca, utvrđene su postupkom razređivanja s primenom selektivnih hranjivih medija. Prvih pet osa objasnjava 86% ukupne varijanse. Prva osa objašnjava 34, 6% varijanse, a odražava procese mikrobiološke mineralizacije i imobilizacije fosfora. Druga osa objašnjava 25, 9% varijanse i odražava mikrobiološku aktivnost i nakupljanje organske materije, N biomase, brojnost Azotobacter sp. i aktivnosti kisele i alkalne fosfomonoesteraze.
Fosfomonoesterazna djelovanja u tlu primarno zavise od organske materije i bioloških faktora i može se koristiti kao parametar biljnog usvajanja fosfora, naročito u uslovima njegove niske koncentracije u tlu.
Ključne reči: mikroorganizmi, zemljište, mikrobiološka biomasa
ADSORPTION OF ARSENITES AND ARSENATES FROM AQUEOUS SOLUTIONS BY APPLICATION OF MODIFIED NATURAL INORGANIC MATERIALS – A KINETIC STUDY
Zoran Bozhinovski1, Kiril Lisichkov2, Mirko Marinkovski2, Stefan Kuvendziev2, Dejan Dimitrovski2, Kostadin Nikolovski2
1“Water Supply and Sewage”, Public Enterprise, Center for Sanitary Control, Skopje,
2University “Ss. Cyril and Methodius”, Faculty of Technology and Metallurgy, Skopje, R. Macedonia
ABSTRACT
Two commercially available adsorbents, white tuff from Strmos region and a material with a commercial name Zeofit obtained from Palanka region, were investigated as possible raw materials for adsorption of arsenites and arsenates from aqueous solutions. These raw materials were modified through chemical insertion of iron within the basic material structure and ionic substitution of calcium and magnesium ions with sodium ions in order to improve the sorptive and ion-exchange properties of studied raw materials. Obtained results from the experimental study of the adsorption of arsenic ions from simulated aqueous solutions suggest that the Zeofit material produced better results than the white tuff material, which showed satisfactory adsorption efficiency only at lower arsenic ions concentrations. Drinking water from the water supply system in Skopje was used for preparation of the studied arsenic ions solutions. Performed kinetic study and resulting kinetic models for both materials, generated a kinetic model of first order for the white tuff material, whereas the Zeofit material adsorption kinetics indicated a pseudo-second order.
Keywords: adsorption, adsorbent modification, modeling, kinetic study
ADSORPCIJA ARSENITA I ARSENATA IZ VODENIH RASTVORA PRIMENOM MODIFIKOVANIH PRIRODNIH NEORGANSKIH MATERIJALA – KINETIČKA STUDIJA
IZVOD
Dva komercijalno dostupna adsorbenta, beli tuf iz regiona Strmoš i materijala sa komercijalnim imenom Zeofit dobijenim iz regiona Palanke, ispitivani su kao moguća sirovina za adsorpciju arsenita i arsenata iz vodenih rastvora. Ove sirovine su modifikovane hemijskim ubacivanjem gvožđa u osnovnu strukturu materijala i jonskom izmenom kalcijuma i magnezijuma sa natrijum jona u cilju poboljšanja sorpcione i jonoizmenjivačke osobine ispitivanog materijala. Dobijeni rezultati eksperimentalnog istraživanja za adsorpciju arsenovih jona iz modelnih vodenih rastvora sugerišu da Zeofit pokazuje bolje rezultate od materijala beli tuf, koji je pokazao zadovoljavajuće rezultate samo pri nižim koncentracijama arsena. Izvršena kinetička studija za oba materijala daju kinetički model iz prvog reda za materijal beli tuf, dok za Zeofitom dobija se kinetički model iz pseudo – drugog reda.
Ključne reči: adsorpcija, modificiranje adsorbenta, modelovanje, kinetička studija
DEPOZICIJA (SUVA) ZAGAĐUJUĆIH MATERIJA U PODRUČJU SEMBERIJE
Bosiljka Stojanović1, Jovan Đuković2, Miladin Drobnjak3
1RiTE Ugljevik, R. Srpska, 2Univerzitet Istočno Sarajevo,Tehnološki
fakultet Zvornik, Zvornik, R.Srpska, 3Pateting, Beograd, Srbija
IZVOD
Zagađujuće materije emitovane u atmosferi se ponovo deponuju na zemljinu površinu kao suva ili mokra depozicija. Suve depozicije se procjenjuju modeliranjem.U ovom radu je procjenjena suva depozcija gasova SO2, NOx i jona NH4+, NO3–, SO4-2, Na+, Mg+2 i Ca+2 u januaru i julu 2013. u Bijeljini i izračunat potencijal zakiseljavanja preko suve depozicije kiselih gasova i jona (PAI(suva)).
Ključne riječi : suva depozicija, zagađujeće materije, imisije,zakiseljavanje
DEPOSITION (DRY) OF POLLUTANTS IN THE AREA SEMBERIJA
ABSTRACT
Pollutants emitted into the atmosphere is again deposited on the ground as wet or dry deposition.Dry depositions are astimated by modeling.In this paper is estimated dry depositions of gases NOx and ions NH4+, NO3–, SO4-2, Na+, Mg+2 i Ca+2 in January and i July 2013th Iin Bijeljina, and then is calculated potential of acidification by dry deposition of acid gases and ions (PAI(dry)).
Key words : dry deposition, pollutants, imission, acidification
