↑ Return to Izdanja 2015 godine

Zaštita Materijala 2. 2015

The advantages of modified air plasma jet method in the process of deposition of hydroxyapatite coatings on the titanium surface

 VUKOMAN JOKANOVIĆ1, MIROLJUB VILOTIJEVIĆ1,
BOŽANA ČOLOVIĆ1, VESNA VUJAČIĆ2, REBEKA RUDOLF3,4

1University of Belgrade, Vinča Institute of Nuclear Sciences, Belgrade, Serbia, 2University of Belgrade,Institute of Chemistry, Technology and Metallurgy, Belgrade, 3University of Maribor, Faculty of Mechanical Engineering, Maribor, Slovenia, 4Zlatarna Celje d.d., Celje, Slovenia

ABSTRACT

The advantages of modified plasma jet construction and its main characteristics were investigated in the process of the hydroxyapatite (CHA) deposition on the surface of titanium substrate. Calculation of the CHA particles velocity and residence time inside of plasma torch PJ-100 were made. The depth of CHA coating, its morphology and its bond with the titanium substrate were investigated. Special care was paid to the extraordinary coating adhesion properties. All the obtained results showed that this plasma jet installation and process of deposition are very promising for obtaining satisfying coatings on the implants for hips, knees and teeth.

Keywords: hydroxyapatite coatings, air plasma jet, titanium substrate, orthopedic application

More >>>

 

Prednosti modifikovane vazdusne plazma mlaz metode u procesu talozenja hidroksiapatitnih premaza na povrsini titanijuma

IZVOD

U radu su istraživane prednosti modifikovanog uređaja za plazma sprejovanje u mlazu, uslovljene specifičnim karakteristikama plazma uređaja, u procesu depozcije kalcijum hidroksiapatita (CHA) na površini titanijum supstrata. Određena je brzina CHA čestica i vreme njihovog boravka u plazma torusu PJ-100 uređaja. Dubina prevlake CHA, njena morfologija i adhezivna veza sa titanijumskom podlogom, posebno su ispitivani. Izuzetna pažnja je posvećena adhezivnim osobinama ovih prevlaka, koje su bolje od svih dosada publikovanih u svetskoj literature. Svi dobijeni rezultati pokazali su da ovako modifikovana plazma instalacija i proces depozicije su veoma obećavajući za dobijanje vrlo kvalitetnih prevlaka na titanovim implantima za kukove, kolena i zube.

Ključne reči: hidroksiapatit premazi, vazdusna plazma mlaz, titanijum podloga, ortopedska aplikacija.

Dalje >>>

 


 

Some considerations related to quantum electronics, acoustics and science of material based
on experiment and theory

MILESA SREĆKOVIĆ1, STANKO OSTOJIĆ2, BRANKA KALUĐEROVIĆ3, ZORAN FIDANOVSKI4, ZORAN LATINOVIĆ1, SANJA JEVTIĆ5, ĐURĐE MILANOVIĆ6

1University of Belgrade,Faculty of Electrical Engineering, Belgrade, 2University of Belgrade, Faculty of Technology and Metallurgy, Belgrade,
3University of Belgrade, Institute Vinča, Materials Sci. Dpt., Belgrade, 4Faculty for Computer, Engineering and Informatics, Belgrade, 5Railway Technical
School, 6Megatrend University, Belgrade, Serbia

ABSTRACT

The coupling of some fundamental sciences and issues arising from it are considered in this paper. The transport and optical characteristics belong to nowadays problems of material science. Some measurements and their interpretations for chosen condensed materials are considered. Various processes, which include directly optical and acoustic processes, are measured for solid and liquid materials. After obtained principal issues of measurement, coupling with them is performed. Principal links include dielectric, resistive, optical and acoustical performances. Nonlinear optical contribution up to optical-laser breakdown can be evaluated from linear data. Micellar laser scattering cover transient effects and is one of the topics in many sciences (including biology and ecology).

Keywords: laser, scattering, micelle, sound, ecology, transport performances, diffusion.

More >>>

 

NEKA RAZMATRANJA ODNOSA KVANTNE ELEKTRONIKE, AKUSTIKE I NAUKE O MATERIJALU
BAZIRANE NA EKSPERIMENTU I TEORIJI

IZVOD

Sprezanje nekih fundamentalnih nauka i mogući izlazi koji proističu se razmatraju u ovom radu. Savremeni problemi nauke o materijalima su vezani za transportne i optičke karakteristike. Neka me­renja i njihove interpretacije za izabrane materijale kondenzovanog stanja su razmotreni. Razni procesi, koji uključuju direktne optičke i akustične procese su mereni za materijale čvrstog i tečnog stanja. Prema osnovnim rezultatima merenja, razmotreno je dalje sprezanje. Glavne veze uključuju dielektrične, otporne, optičke i akustične osobine. Nelinearni optički doprinosi, koji dovode do optičkog-laserskog proboja, može se oceniti iz linearnih podataka. Rasejanje laserskih snopova na micelama pokriva i prelazne procese i jedna je od aktuelnih oblasti u mnogim naukama (uključujući biologiju i ekologiju).

Ključne riječi: rasejanje, laser, micele, brzina zvuka, ekologija, transportne osobine, difuzija.

Dalje >>>

 


Priprema otpadnih ulja u proizvodnji biodizela radi smanjenja sadržaja slobodnih masnih kiselina

NATAŠA ĐURIŠIĆ-MLADENOVIĆ,
ZLATICA PREDOJEVIĆ, BILJANA ŠKRBIĆ

Univerzitet u Novom Sadu, Tehnološki fakultet, Novi Sad, Srbija

IZVOD

Biodizel predstavlja obnovljivo biorazgradivo gorivo, koje se smatra efikasnom alternativom fosilnom dizel gorivu. Proizvodi se prvenstveno od ulja gajenih biljaka, što utiče na njegovu visoku cenu i nekonkurentnost na tržištu u odnosu na dizel gorivo. Zbog toga, jeftine, nejestive sirovine, tzv. sirovine 2. generacije, imaju značajan potencijal u proizvodnji biodizela. U radu je predstavljen potencijal otpadnih biljnih ulja kao sirovina za biodizel, kao i negativan uticaj povećanog sadržaja slobodnih masnih kiselina (SMK) u njima na proizvodnju biodizela konvencionalnim postupcima. Analizirani su postupci smanjenja sadržaja SMK; poseban osvrt je dat na kiselo katalizovanu esterifikaciju, uzi pregled istraživanja u kojima se koristi sumporna kiselina.

Ključne reči: biodizel, otpadna ulja,slobodne masne kiseline, esterifikacija, sumporna kiselina

Dalje >>>

 

PRETREATMENT OF WASTE OILS WITH HIGH FREE FATTY
ACIDS CONTENT FOR BIODIESEL PRODUCTION

ABSTRACT

Biodiesel is considered a promising renewable biofuel alternative to petroleum-based diesel fuel, because of its biodegradability and non-toxicity. Generally, it is produced from the vegetable, edible oils obtained from the cultivated crops; the expenses of such raw materials are the major contributor to the cost of biodiesel production resulting in a biofuel that is uncompetitive with diesel. Therefore, low-cost non-edible lipid feedstocks (so-called the 2nd generation feedstocks) have a great potential in competetive and sustainable production of biodiesel. This paper presents a potential of waste oils as raw materials for biodiesel production, explaining the problems of the elevated contents of free fatty acids (FFAs) in such oils in the conventional production process with an alkaline catalyst. Among the methods for pretreatment of feedstocks with high FFAs content, the paper gives a brief overview of the acid pre-esterification, reviewing the studies that have investigated application of sulphuric acid as the most common acid catalyst.

Key words: biodiesel, waste oil, free fatty acids, esterification, sulphuric acid

More >>>

 


 

Lead concentration in soil inside the area of former
battery
production factory, Berat, Albania

MIRELA ALUSHLLARI, NIKOLLA CIVICI

University of Tirana, Institute of Applied Nuclear Physics,Tirana, Albania

ABSTRACT

Lead is a trace element in the earth’s crust, but it is not essential element. Lead poisoning is an important environmental pollutant that can have life-long adverse health effects. Lead is widely used in industry for building construction, lead-acid batteries, bullets, shot, etc. The current study reports the determination of lead concentration in surface and profile soil samples, inside the territory of former Factory Production of Batteries, Uznove, Berat, Albania. We have collected a total of 10 soil samples. The representative soil samples were analyzed using atomic absorption spectrometry for their lead content. The concentration of lead in soil samples are compared with the Maximum Contaminant Levels (MCL) specified by the Directive 86/278/EEC. Also, from results obtained we have calculated Hazardous Quoted (HQ). HQ in representative surface soil samples was 3.78–18.88 times higher than normal value. Concentration of lead in profile of soils tends to decrease. The level of lead in the profile soil samples, in the depth of 80-90 cm has decreased about 2-50 times compared to the concentration of lead in surface soil samples.

Keywords: lead, surface and profile soil samples, Atomic Absorption Spectrometry (AAS).

More >>>

 

Ispitivanje koncentracije olova u zemljištu u krugu
bivse fabrike za proizvodnju baterija

IZVOD

Olovo je element u tragovima u zemljinoj kori, ali nije bitan elemenat. Olovo je važan zagađivač životne sredine, koji može imati trajne štetne posledice po zdravlje. Olovo ima široku primenu u industriji za izgradnju objekata, olovnih baterija, itd. Izvršena su određivanja koncentracije olova u površinskim i profil zemljištu uzoraka, unutar teritorije bivše fabrike za proizvodnju baterija, Uznove, Berat, Albanija.

Uzeto je ukupno 10 uzoraka zemljišta. Reprezentativni uzorci zemljišta su analizirani korišćenjem atomske apsorpcione spektrometrije na olovo.  Koncentracije olova u uzorcima zemljišta su u poređenju sa maksimalnim nivoima zagađenosti vazduha (MCL) utvrđeni Direktivom 86/278 / EEC. Takođe, za dobijene rezultate  izračunati su indeksi HQ. HQ indeks u površinskim uzorcima tla je 3.78-18.88 puta veći od normalne vrednosti. Koncentracija olova u profilu zemljišta ima tendenciju da se smanjuje.  Koncentracija olova u uzorcima zemljišta u profilu, u dubini od 80-90 cm je smanjena za 2-50 puta u odnosu na koncentracije olova u površinskim uzorcima zemljišta.

Ključne reči: olovo, površina i profil tla, zagađenje sredine, atomska apsorpciona spektrometrija (AAS).

Dalje >>>

 


Structural properties of carbon microspheres obtained
by hydrothermal treatment of fructose

SANJA KRSTIC1, BRANKA KALUĐEROVIC1,
VLADIMIR DODEVSKI1, ANDJELKA Z. BJELAJAC2

1University of Belgrade, Institute of Nuclear Sciences, Laboratory for Material Science,  Belgrade, 2University of Belgrade, Faculty of Technology and Metallurgy,  Belgrade, Serbia

ABSTRACT

A carbon-rich solid product has been synthesized by hydrothermal treatment from fructose with HNO3 at temperature of 140°C. The concentration of the precursor was changed in order to investigate how its change influences formation of carbon microspheres. pH value for every sample was the same, i.e. 1. The formation of the carbon rich solid through the hydrothermal carbonization of fructose is the consequence of dehydration reactions. Obtained carbon material is made of spherical micrometer-sized particles with the diameter in the 1-6 µm range, which can be modulated by modifying the concentration of fructose in solution. The best results are obtained with smaller concentrations of fructose. Spherical particles have more regular shape and they are less agglomerated. The structure and surface chemical properties of obtained material were characterized by scanning electron microscopy (SEM), Fourier-transform infrared (FTIR) spectra and elemental analysis.

Keywords: carbon microspheres; hydrothermal synthesis; fructose.

More >>>

 

Strukturne osobine mikrosfera ugljenika dobijenih hidrotermičkim tretmanom fruktoze

IZVOD

Čvrsti proizvod bogat ugljenikom je sintetizovan hidrotermičkim tretmanom fruktoze sa HNO3 na temperaturi od 140 °C. Koncentracija prekursora bila je menjana da bi se istražilo kako njegova promena utiče na formiranje mikrosfere atoma. pH vrednost za svaki uzorak bila je isti 1. Formiranje čvrstog proizvoda bogatog ugljenikom preko hidrotermičke karbonizacije fruktoze posledica je dehidracionih reakcija. Dobijeni ugljeni materijal izrađen je od sfernih čestica veličine prečnika od 1 do 6 µm, koji se može modulisati promenom koncentracije fruktoze u rastvoru. Najbolji rezultati se dobijaju sa manjim koncentracijama fruktoze. Sferne čestice imaju više pravilan oblik i oni su manje aglomerisane. Strukture i površinske hemijske osobine dobijenog materijala su sagledavane skeniranjem elektronskim mikroskopom (SEM) , FTIR-om i spektralnim i elementarnim analizama.

Ključne reči:  ugljene mikrosfere, hidrotermalna sinteza, fruktoza.

Dalje >>>

 


 

Reflectivity from electrochemically protected Nb surfaces

IRENA MICKOVA

University “ Ss. Cyril and Methodius”, Faculty of Technology and
metallurgy,  Skopje, Republic of Macedonia

ABSTRACT

Corrosion resistance of fine mechanically polished and electro-polished Nb surfaces were tested by elliposmetric measurements the reflectivity at various angle of incidence. The same measurements were also repeated on electro-polished Nb surface anodically oxidized in 1M H2SO4 during 30 s in the potential/voltage range from 0 to 100 V. From the minimum value of measured reflectivity parallel to plane of incidence, the Brewster angle for each investigated sample was determined. The simultaneous measurements of corrosion parameters Brewster angle have shown that the values of Brewster’s angle should be used for fast testing the quality of protected metal surfaces.

Keywords: niobium, anodic oxide films, ellipsometry, Brewster’s angle.

More >>>

 

REFLEKTIVNOST ELEKTROHEMIJSKI ZAŠTIĆENIH Nb POVRŠINA

IZVOD

Koroziona otpornost fino mehanički poliranih i elektropoliranih Nb površina testirana je pomoću elipsometriskih merenja reflektivnosti kod različitih upadnih uglova incidentnog zraka. Ista merenja bila su ponovljena i kod elektropoliranih Nb površina anodno oksidiranih u 1 M H2SO4 u vremenu od 30 s za potencijalno/naponsko područje od 0 do 100 V. Od minimalne vrednosti merene reflektivnosti, koja je paralelna upadnoj ravni, odredjivan je Brewsterov ugao za svaki ispitivani primerak. Simultana merenja korozionih parametara i Brewsterovog ugla pokazala su da vrednosti Brewsterovih ugla mogu da se koriste za brzo testiranje kvaliteta zatićenih metalnih površina.

Ključne reči: niobijum, film anodnog oksida, elipsometrija, Brewsterov ugao.

Dalje >>>

 


 

 

Materials with potentially bioactive properties –
preparation and characterization of electrospun
poly(vinyl alcohol)/beeswax fiber web

MARGARITA NEZNAKOMOVA1, NIKOLAY TODOROV2

1Technical University of Sofia, Mechanical Technology Faculty, 2Technical University of Sofia, Faculty of power engineering, Sofia, Bulgaria

ABSTRACT

Currently is observed a great interest in the use of bioactive natural products for modification and functionalization of fibers to produce antimicrobial protective medical textiles. One of the areas is related to the ability to obtain electrospun nanofibers with potential bioactive properties. The aim of this study was to produce and characterize nanofibers from an aqueous solution of poly (vinyl alcohol (PVA) and beeswax (BW). To investigate the possibility of obtaining nanofibers with addition of beeswax is done in two forms – as solution and micro emulsion. Beeswax has a rich chemical composition, a mixture of proteins, vitamins, trace elements, esters, fatty acids, carbohydrates, lipids.  Itself smoothies and moisturizes the skin, helps in the treatment recovery of burned skin, slows aging and has antibacterial activity.

The fibers were produced in laboratory conditions with single nozzle spin-draw device.  The nanofibers are based on 9% PVA solution and 2% (by weight) beeswax as additive. Аs a pad for the electrospun nanofibers has been used thermobonded medical nonwoven textile.  The structure of the nanofiber layers is investigated by scanning electron microscope (SEM) and atom force microscope (AFM). The fabrication of poly (vinyl alcohol) non-woven materials by electrospinning of polymer solutions, containing various concentrations of cationic, anionic amphoteric and nonionic surfactants is a complicated process. The type of additive which is used for the functionalization of the fibers changes an electroconductivity, surface tension, viscosity, therefore rheological method for controlling the process was used. The properties of the electrospun materials like air permeability, water vapor permeability, mass and thickness are examined as well. The average diameters of the produced bicomponent fibers were in the range 100-420 nm. Water-resistant nanofibrous materials were obtained by thermal crosslinking at 100 oCfor 12 h. Fourier transformed infrared spectroscopy (FTIR) showed that PVA/BW nanofibers are present in a stable form.

A further project employs to examine the received bilayer material to determine their biological activity and their potential use as plasters for regeneration of skin injuries.

Keyword: PVA/BW, nanofibers, produce, characterize, water-resistant, FTIR, biological activity

More >>>

 

Materijali sa potencijalno bioaktivnim svojstvima –
Sinteza i karakterizacija nanovlakana
poli (vinil alkohol ) / pčelinji vosak

IZVOD

Trenutno je primetno veliko interesovanje za korišćenje biološki aktivnih prirodnih proizvoda za modifikaciju i funkcionalizaciju vlakana za proizvodnju antimikrobnog zaštitnog medicinskog tekstila. Jedna od oblasti odnosi se na mogućnost dobijanja elektrospun nanovlakana sa potencijalnim bioaktivnim svojstvima. Cilj ove studije bio je proizvodnja i karakterizacija nanovlakana sa vodenim rastvorom od poli ( vinil alkohol (PVA ) i pčelinjim voskom (BV).  Da bi se ispitala mogućnost dobijanja nanovlakana, dodatak pčelinjeg voska vršio se u dva oblika – kao rastvor i mikroemulzija. Vosak ima bogat hemijski sastav, smešu proteina, vitamina, mikroelemenata, estra, masne kiseline, ugljene hidrate, lipide. Sam vosak vlaži kožu, pomaže u oporavku i lečenju spaljene kože, usporava starenje i ima antibakterijsko dejstvo .

Vlakna su proizvedena u laboratorijskim uslovima sa jednom mlaznicom spin-drav uređaja. Nanovlakna se tretiraju sa 9 % PVA rastvorom i 2 % (po težini) voska kao aditiv. Kao tampon za elektrospun nanovlakna  koristi se termofiksirani medicinski netkani tekstil. Struktura nanofiber slojeva je ispitivana elektronskim mikroskopom – SEM i AFM.  Izrada poli (vinil alkohola ) netkanih podmetača od elektrospin polimernih rešenja, koja sadrže različite koncentracije katjonskih, anjonskih, amfoterni i nejonskih surfaktanata je komplikovan proces. Vrsta aditiva koja služi za funkcionalizaciju vlakana primenjuje se za elektroprovodnost, površinski pritisak i viskozitet, te je stoga korišćena reološka metoda za kontrolu procesa. Svojstva elektrospun materijala, kao što su propustljivost vazduha, propustljivost vodene pare, masa i debljina, su se pokazala kao dobra. Prosečni prečnici proizvedenih vlakna su bili u opsegu 100-420 nm. Vodootporni nanofiber podmetači su dobijeni termalnim postupkom na 100oC  tokom 12 h. Ispitivanja pomoću FTIR  pokazala su da PVA / BV nanovlakna su prisutna u stabilnom obliku.

Dalja istraživanja će se obavljati da se ispita pripremljeni dvoslojni materijal i da se odredi njihova biološka aktivnost i potencijalna upotreba kao malterijala za regeneraciju kože posle povreda.

Ključne reči: PVA/BW, nanofiber, proizvodnja, karakterizacija, vodootporan, biološka aktivnost.

Dalje >>>

 


Co-Mo-Cr alloys for dentistry obtained
by vacuum precise casting

ZVONKO GULIŠIJA, ALEKSANDRA PATARIĆ, MARIJA MIHAILOVIĆ

Institute for Technology of Nuclear and Other Mineral Raw Materials, Belgrade, Serbia

ABSTRACT

There are several biocompatible Co-Cr-Mo alloy compositions, as well as technological processes suitable for obtaining the tablet samples aimed to produce dental implants and orthodontic devices. Here presented Co-Cr-Mo alloy, besides its biocompatibility, corrosion resistance, and nickel absence, is favorable for its mechanical properties, such as hardness, tensile and fatigue strength.

The technology for raw materials preparation and manufacturing of a Co-Cr-Mo alloy for dental implants vacuum precise casting is presented here. Besides the technological process characteristics, there are the chemical analysis of raw materials, alloy obtaining guidelines and microstructure of as-cast samples.

Key words: Co-Cr-Mo alloy, dental implants, vacuum casting.

More >>>

 

LEGURE Co-Mo-Cr ZA PRIMENU U STOMATOLOGIJI
DOBIJENE PRECIZNIM LIVENJEM U VAKUUMU

IZVOD

Za proizvodnju odlivaka od kojih se izrađuju zubni implantati, ortodontski aparati i pomoćni mate­rijali koristi se više legura Co-Cr-Mo, različitog sastava. Ovde je reč o leguri, koja pored odsustva nikla, svoje biokompatibilnosti i otpornosti na koroziju, ima odlične mehaničke karakteristike, kao što su tvrdoća, zatezna čvrstoća i žilavost.

Predstavljena je tehnologija pripreme sirovina, kao i izrada same legure u vidu uzoraka-tabletica od kojih se izradjuju zubni implantati, tehnologijom preciznog livenja u vakuumu, korišćenjem metode topivih modela. Osim eksperimantalnih parametara, praćen je hemijski sastav od polaznih sirovina do gotove legure. Prikazana je mikrostruktura uzoraka u livenom stanju.

Ključne reči: Co-Cr-Mo legura, dentalni implantati, livenje u vakuumu

Dalje >>>

 


 

Adsorption kinetic models of heavy metal ions on granular activated carbon

ALEKSANDRA PORJAZOSKA KUJUNDZISKI,
LILJANA MARKOVSKA, VERKA MESHKO

International Balkan University, Faculty of Engineering, Skopje, Republic of Macedonia

ABSTRACT

Adsorption is considered as one of the most effective and cost efficient methods in water effluents purification. Frequently used adsorbent for heavy metals removal is activated carbon. The adsorption of lead ions from wastewater model solutions on activated carbon has been studied by a batch adsorber. Experiments were performed at constant temperature, while the concentration of lead ions in the solutions has been varied.

Using the MatLab software the parameters for the Langmuir and Freundlich adsorption isotherms were determined. The experimental data obeys the Langmuir isotherm, and the maximum sorption capacity determined was 17.09 mg g-1. The impact of the quantity of activated carbon and the initial concentration of lead ion on adsorption kinetics has been studied. The kinetics models for the first, pseudo-first, second and pseudo-second-order reaction were fitted to the experimentally obtained data by MatLab software. Data obtained by the kinetics study of Pb2+ adsorption on activated carbon, might be useful in the selection of the most probable mechanism of the adsorption process. It has been shown that the pseudo-second-order model explains the experimental data the best.

Key words: adsorption, lead sorption, adsorption isotherms, kinetics

More >>>

 

KINETIČKI MODELI ADSORPCIJE TEŠKIH METALA GRANULIRANIM
AKTIVNIM UGLJEM

IZVOD

Adsorpcija je jedna od najefikasnijih i najekonomičnijih metoda u pročišćavanju otpadnih voda, pri tom granulirani aktivni ugalj je jedan od najkorišćenjijih adsorbensa za teške metale. U ovom je radu ispitivan uticaj količine aktivnog uglja i početne koncentracije olova u rastvoru na kinetiku adsorpcije, pri konstantnoj temperaturi, koristeći šaržni adsrober. Parametri Langmuir-ove i Freundlich-ove adsorpcione izoterme, kao i kinetički modeli za prvi, drugi, pseudo-prvi i pseudo-drugi red reakcije su određeni kompjuterskim programom MatLab. Pokazalo se da su Langmuir-ova izoterma i model pseudo-drugog reda pogodniji ako se u obzir uzme celo eksperimentalno područje. Maksimalni kapacitet sorpcije je 17.09 mg g-1.

Ključne reči: adsorpcija, sorpcija olova, adsorpcione izoterme, kinetika

Dalje >>>

 


 

Korozione karakteristike trojne legure ZnNiCo elektrohemijski istaložene korišćenjem različitih anoda

SAŠA MIĆIN1, SANJA MARTINEZ2, BORISLAV N. MALINOVIĆ3,
VEDRANA GROZDANIĆ4,ZORAN JANKOVIĆ5

1Ekvator, Banja Luka, R.Srpska, BiH, 2Sveučilište u Zagrebu, Fakultet kemijskog inženjerstva i tehnologije, Zagreb, Hrvatska, 3Univerzitet u Banja Luci, Tehnološki fakultet, Banja Luka, R.Srpska, BiH, 4Istarska razvojna agencija IDA d.o.o., Centar za istraživanje materijala Istarske županije – METRIS, Pula, Hrvatska, 5Viz Zaštita,  Banja Luka, R.Srpska, BiH

IZVOD

Vršena su ispitivanja korozionih karakteristika elektrohemijski istaloženih metalnih prevlaka trojne legure ZnNiCo korištenjem različitih anoda prilikom taloženja. Analiza korozionih karakteristika je vršena pomoću polarografske metode i spektroskopije elektrohemijske impedance. Zbog različitih vrijednosti prenapona izdvajanja kiseonika, svaka od anoda daje različit napon ćelije koji raste redosljedom MMO<Ti/Pt<BDD. Polarografska ispitivanja pokazala su najmanju brzinu korozije (88 µm/ god) prevlake istaložene korištenjem Ti/Pt anode, dok su brzine korozije za preostale dvije prevlake približno dvostruko veće. Mjerenja impedancije pokazuju dvije vremenske konstante koje se mogu  pripisati dielektričnim svojstvima sloja korozionih produkata i prevlake. Otpor oba sloja približno je dvostruko veći za prevlaku istaloženu korištenjem Ti/Pt anode.

Ključne riječi : trojna legura ZnNiCo, korozione karakteristike, anoda

Dalje >>>

 

Corrosion characteristics of ZnNiCo ternary alloy
electrochemically deposited by using different anodes

 

ABSTRACT

Corrosion characteristics, of ZnNiCo ternary alloy metallic coatings electrochemically deposited by using different anode shave been investigated. Analysis of corrosion characteristics was performed by using the polarographic methods and electrochemical impedance spectroscopy.Due to different values of oxygen overvoltage, each anode gives different cell voltage that increases in the order of MMO<Ti/Pt<BDD. Polarigraphic measurements showed the lowest corrosion rate (88 mm/year) of the coating deposited using Ti/Pt anode, while the corrosion rate for the remaining two coatings is approximately twice as large. The impedance measurements have shown two time constants that can be attributed to the dielectric properties of the layer of corrosion products at the coating surface and the coating layer itself. In concordance with polarigraphic measurements the resistance of both layers is approximately twice higher for the coating obtained using Ti/Pt anode.

Keywords: ternary alloy ZnNiCo, corrosion characteristics, anode.

More >>>

 


 

Investigation of phenol adsorption on macroporous
polymeric adsorbents

LJUBIŠA M. IGNJATOVIĆ1, ALEKSANDRA M.TASIĆ1,
IVANA D. SREDOVIĆ IGNJATOVIĆ2,
ALEKSANDRA B. NASTASOVIĆ3

1University of Belgrade, Faculty of Physical Chemistry, Belgrade, 2University of Belgrade, Faculty of Agriculture, Zemun, 3University of Belgrade, Institute of Chemistry, Technology and Metallurgy,  Belgrade, Serbia

 

ABSTRACT

This work reports results on phenol adsorption from aqueous solution by porous copolymers based on glycidyl methacrylate: two samples of macroporous crosslinked poly(glycidyl metha­crylate-co-ethylene glycol dimethacrylate), were synthetized by suspension copolymerisation with ethylene glycol dimethacrylate. In addition, the two copolymer samples were functionalized with ethylene diamine. The amounts of adsorbed phenol were presented in the form of adsorptions isotherms, which were interpreted using Langmuir, Freundlich and Sips’ equations. The first was found to express high level of agreement with experimental data. Phenol adsorption indicate the homogeneous distribution of active sites present on the investigated polymers. It was found that adsorption of phenol on copolymers is fast and depends on the presence of amino groups and on the pore size. From the obtained results, it was possible to distinguish macroporous polymer as a material which possesses the capacity for adsorption of phenol comparable to that of activated carbon.

Keywords: phenol, adsorption, macroporous polymers, kinetics, capacity

More >>>

 

ISPITIVANJE ADSORPCIJE FENOLA NA MAKROPOROZNIM
POLIMERNIM ADSORBENSIMA

IZVOD

Ovaj rad se bavi proučavanjem adsorpcije fenola iz vodenih rastvora na kopolimerima različitih poroznih karakteristika i polarnosti. Korišćeni adsorbensi se baziraju na glicidil metakrilatu: dva uzorka makroporoznog poli(glicidil metakrilat-co-etilen glikol dimethakrilat) su  sintetisani suspenzionom kopolimerizacijom sa etilen glikol dimetakrilatom. Dodatno, dva kopolimera su  funkcionalizovani sa etilen diaminom. Količina adsorbovanog fenola je predstavljena u vidu adsorpcionih izotermi, koje su interpretirane korišćenjem Langmuir-ove, Freundlich-ove i Sips-ove jednačine: prva od ovih daje visok nivo slaganja sa eksperimentalnim podacima. Adsorpcija fenola ukazuje na homogenu raspodelu aktivnih mesta prisutnih u ispitivanim polimernim sistemima. Rezultati dobijeni u ovom istraživanju pokazuju da adsorpcija fenola na ispitivanim kopolimerima zavisi od prisustva amino grupa i od veličine pora. Adsorpcija fenola iz vodenih rastvora je brza u slučaju svih korišćenih adsorbenasa. Na osnovu dobivenih rezultata, može se zaključiti da su makroporozni polimeri materijali čije je adsorpcioni kapacitet za fenol uporediv sa onim koji ima aktivni ugalj.

Ključne reči: fenol, adsorpcija, makroporozni polimeri, kinetika, kapacitet

Dalje >>>

 


Održiva konverzija otpadne biomase primenom postupka
hidrotermalne karbonizacije

JELENA T. PETROVIĆ1, MARIJA L. MIHAJLOVIĆ1, MIRJANA D. STOJANOVIĆ1,
MARIJA R. STANOJEVIĆ1, MARIJA S. PETROVIĆ1, JELENA V. MILOJKOVIĆ1, ČASLAV M. LAČNJEVAC2

1Institut za tehnologiju nuklearnih i drugih mineralnih sirovina ITNMS, Beograd,   2Univerzitet u Beogradu, Poljoprivredni fakultet, Zemun, Srbija

IZVOD

Hidrotermalna karbonizacija predstavlja postupak prevođenja vlažnog organskog materijala primenom povišene temperature i pritiska u hidročađ, proizvod sličan uglju. Dobijena hidročađ, u zavisnosti od prirode biomase, može biti upotrebljena kao zamena za fosilni ugalj, adsorbent različitih polutanata, dodatak za poboljšanje plodnosti zemljišta i dr. Ovaj rad pruža uvid u osnovne reakcione mehanizme, kao i uticaj procesnih parametara na dobijanje hidročađi. Takođe, istaknut je značaj i prednost postupka hidrotermalne karbonizacije otpadne biomase u odnosu na tradicionalne metode konverzije, kao i aktuelne primene dobijenih proizvoda.

Ključne reči: hidrotermalna karbonizacija, hidročađ, biomasa, gorivo

Dalje >>>

 

Sustainable conversion of waste biomass using hydrothermal carbonization method

ABSTRACT

Hydrothermal carbonization represents a process for converting a wet organic material at elevated temperature and pressure in hydrochar, coal-like product. The resulting hydrochar, depending on the nature of biomass, can be used as a substitute for fossil coal, adsorbent of various pollutants, soil fertility supplement and others. This paper provides insight into the reaction mechanisms, as well as the influence of process parameters. It also highlighted the importance and advantage of the process of hydrothermal carbonization of biomass compared to traditional methods of conversion, as well as the actual implementation of the product.

Keywords: hydrothermal carbonization, hydrochar, biomass, fuel.

More >>>

 


 

 

Ispitivanja kvaliteta vode za piće iz individualnih bunara
u selu Dubravica u Braničevskom okrugu

MILOŠ B. RAJKOVIĆ1, MIRJANA STOJANOVIĆ2, SLAĐANA MILOJKOVIĆ3

1Univerzitet u Beobradu, Poljoprivredni fakultet, Beobrad, 2Institut za tehnologiju nuklearnih i drugih mineralnih sirovina, Beograd, 3Zavod za zaštitu zdravlja, Požarevac, Srbija

IZVOD

Kvalitet vode za piće: fizičko-hemijska i mikrobiološka ispravnost iz individualnih bunara iz sela Dubravica proverena  je metodama preporučenim Pravilnikom o higijenskoj ispravnosti vode za piće. Sadržaj teških metala u vodi za piće utvrdjen je metodom indirektnog određivanja na osnovu kamenca istaloženog na grejaču kućnog bojlera. Dobijeni kamenac ispitivan je skenirajućom elektronskom mikroskopijom (SEM), rendgenskom difrakcionom analizom (RDA) i metodom termogravimetrijske (TG) i diferencijalne termičke analize (DTA). Fizičko-hemijska i mikrobiološka ispitivanja ukazala su na potpunu zdravstvenu ispravnost vode za piće. Rezultati sadržaja teških metala pokazali su da je indirektna metoda preciznija i pouzdanija, jer može detektovati koncentracije teških metala (u ispitivanim uzorcima Cd i Pb) koji se nalaze ispod praga detekcije klasičnim metodama analize vode. Ovo je veoma bitno jer se na taj način prati njihovo unošenje u dužem vremenskom periodu i mogu se preduprediti eventualne posledice po zdravlje ljudi.Sadržaj urana je ispod zakonom dozvoljene vrednosti, dok metoda frakcione ekstrakcije ukazuje na njegovo antropogeno poreklo.

Ključne reči: kvalitet vode za piće, individualni bunari, Braničevski okrug.

Dalje >>>

Investigation of drinking water quality from the individual wells from the Dubravica village in Braničevo district

 

ABSTRACT

The water quality of drinking water: physico-chemical and microbiological safety of the individual wells from the Dubravica village was investigated with the methods recommended by Regulations of hygienic quality of drinking water. The method of indirect determinations was used for testing the content of heavy metals in drinking water based on the scale sedimented on the house water heater. The scale was examinated  with scanning electron microscropy (SEM), X-ray diffraction analysis (XRD) and the method of thermogravimetric (TG) and differential thermal analysis (DTA). Physico-chemical and microbiological examinations have shown that the drinking water from individual wells are completely safe for use.  The results of heavy metals contents showed that the indirect method is more precise and more reliable because it can detect the concentration of heavy metals (in the examined samples of Cd and Pb) that are below the threshold of detection by classical methods of water analysis.This is very important because, in this way, the use of heavy metals is monitored in long period of time and it can prevent potential effects on human health. The uranium content is below the allowed value prescribed by law, but the method of fractional extraction points to its anthropogenic origin.

Keywords:  drinking water quality, individual wells, Braničevo district

More >>>

 


 

Primena eksergijske analize u reciklažnim tokovima

BRANISLAV MARKOVIĆ1, MIROSLAV SOKIĆ1, ILIJA ILIĆ2, VASO MANOJLOVIĆ1, ZVONKO GULIŠIJA1, DRAGANA ŽIVKOVIĆ3, NADA ŠTRBAC3

1Institut za tehnologiju nuklearnih i drugih mineralnih sirovina, Beograd, 2Univerzitet u Beogradu,Tehnološko-metalurški fakultet, Beograd, 3Univerzitet u Beogradu,Tehnički fakultet u Boru, Bor, Srbija

IZVOD

Materijali za recikliranje uvek sadrže izvestan stepen nečistoća. Prisustvo nečistoća tj. kontaminacija u reciklažnim tokovima izaziva promenu u izvornom sastavu materijala za reciklažu. Usled toga, kvalitet materijala može se smanjivati u svakom narednom koraku reciklaže. Pored toga, resursi nižeg kvaliteta proizvedeni su iz resursnih tokova koji su u izvornom obliku imali viši kvalitet. Ovakvi gubici kvaliteta ne mogu da se mere masenim bilansima, isto kao što se degradacija kvaliteta ne može prikazati samo merenjem mase. Za proračun svih gubitaka prouzrokovanih reciklažnom kontaminacijom, svi dalji procesi reciklaže potrebni da bi se materijali vratili nazad u resursne cikluse moraju biti uključeni. U ovom radu prikazan je metod za izračunavanje eksergijskog sadržaja i eksergijskog gubitka metalnih rastvora u toku iskorišćnja i reciklaže. Gubici pripisani reciklaži ili tačnije materijalni gubici, gubici usled kontaminacije drugim metalima i posledično potreba za razblaživanjem, mogu se koristiti kao indikatori gubitka kvaliteta materijala i efikasnosti korišćenja resursa u proizvodnim sistemima. Dakle, ovde je eksergija predložena kao mera efikasnosti korišćenja resursa. U radu su proračuni eksergijskih gubitaka tokom reciklaže prikazani na primeru aluminijumskog otpada.

Ključne reči: eksergija, gubici, reciklažna kontaminacija, degradacija kvaliteta, efikasnost resursa

Dalje >>>

 

APPLICATION OF EXERGY ANALYSIS IN RECYCLING STREAMS

ABSTRACT

Materials for recycling always contain a certain degree of contamination. The presence of impurities i.e. contamination in the recycling streams causes a change in the composition of the original materials to recycle. As a result, the quality of materials can be reduced in each successive step of recycling. In addition, the resources of lower quality are produced from the resource flows which had a higher quality in their original form. This kind losses of quality cannot be measured by mass balance, as well as the quality degradation not only can display measurements of mass. For the calculation of all losses caused by recycling contaminations, all further recycling processes required to return the materials back into resource cycles must be included. The method for calculating the exergy content and exergy losses of metal solutions during recovery and recycling is presented in this paper. The losses attributed to recycling, namely the material losses, the contamination losses with other metals, and the consequent need for dilution can be used as indicators of the quality loss of materials and of the efficiency of resource use in product systems. Therefore, exergy is proposed here as a measure of the efficiency of resources use. This paper presents calculations of exergy losses during recycling shown in the case of aluminum waste.

Keywords: exergy, losses; recycling contamination; quality degradation, resource efficiency.

More >>>

 


 

Razvoj hidrauličnih fluida za tešku mehanizaciju

MARICA DUGIĆ1, PERO DUGIĆ1, BRANKA DUGIĆ KOJIĆ1,

ZORAN PETROVIĆ2, VLADAN MIĆIĆ2

1Rafinerija ulja Modriča, Modriča, 2Univerzitet u Istocnom Sarajevu, Tehnološki fakultet  Zvornik, Zvornik, R.Srpska, BiH 

IZVOD

Za hidraulične fluide usvojene su brojne klasifikacije i specifikacije koje su izradile organizacije za standardizaciju, čiji zahtjevi definišu kvalitetne nivoe i utvrđene metode za njihovo ispitivanje. Zahtjeve za kvalitet hidrauličnih ulja definišu i konstruktori i proizvođači hidraulične opreme (OEM – Original Equipment Manufacturer). Razvoj specifikacija hidrauličnih ulja,  u ovom slučaju namijenjenih za tešku mehanizaciju, odvijao se u skladu sa promjenama u konstrukciji opreme kod hidrauličnih sistema, posebno pumpi, materijala za crijeva i filtere i promjene zapremine rezervoara za hidraulične fluide. U radu je prikazan trend rasta zahtjeva za kvalitet hidrauličnih ulja za tešku mehanizaciju i promjene u sastavu fluida i njihovih  funkcionalnih karakteristika.

Ključne riječi: klasifikacije, specifikacije, hidraulični fluidi

Dalje >>>

 

DEVELOPMENT OF HYDRAULIC FLUID FOR HEAVY MACHINERY

ABSTRACT

Various classifications and specifications for hydraulic fluids are prescribed, that were developed by standardization organizations, whose demands define quality levels and appointed methods for its testing. Hydraulic fluids quality demands are defined by constructors and manufacturers of hydraulic equipment (OEM – Original Equipment Manufacturer).Development of specifications for hydraulic oils, in this case aimed for heavy machinery, are in accordance with changes in equipment construction for hydraulic systems, especially pumps, hoses and filters materials and changes in reservoir volume for hydraulic fluids. In this paper we presented the rise in demands trends for heavy machinery hydraulic oils quality, shown through changes in fluid composition and its functional characteristics.

Key words: classifications, specifications, hydraulic fluids

More >>>

 


 

Application of permeable materials for CBRN protective equipment

RADOVAN KARKALIĆ1, VESELIN MASLAK2,
ALEKSANDAR NIKOLIĆ2, MIRJANA KOSTIĆ3, DALIBOR
JOVANOVIĆ4, ŽELJKO SENIĆ5, ZLATE VELIČKOVIĆ5

1University of Defense, Military academy, Belgrade, 2University of Belgrade, Innovation Center, Faculty of Chemistry, Belgrade, 3University of Belgrade, Faculty of Technology and Metallurgy, Belgrade, 4Technical Test Center, Belgrade, 5Military Technical Institute, Belgrade, 6University of Defense,Military academy, Belgrade, Serbia

ABSTRACT

The new concept of chemical, biological, radiological and nuclear combat clothing offers the opportunity of substantial cost savings by eliminating the need for additional, CBRN overgarments, whose high weight and poor breathability may cause a physiological overload of the soldier. These specific clothing made of filtrosorption material has been designed for modern soldier, increasing his efficiency and reducing total costs. Textile materials embedded in the suit have excellent physical and mechanical properties, air and moisture permeability after climatic treatment and practical usage. During testing of chemical protective overgarment’s physiologic suitability the ergometric indicators were determined.

Key words: chemical protection, CBRN clothing, SaratogaTM material, activated charcoal, physiologic suitability

More >>>

 

PRIMENA FILTROSORPCIONIH MATERIJALA ZA NHB ZAŠTITNU OPREMU

IZVOD

Novi koncept NHB zaštitne odeće pruža mogućnost velike uštede, eliminišući potrebu za primenu dodatnih NHB zaštitnih sredstava, čija velika masa i loša propustljivost vazduha mogu dovesti do fizioloških preopterećenja vojnika. Ova specijalna zaštitna odeća, izrađena od filtrosorpcionih materijala, je dizajnirana za savremenog vojnika, što mu povećava efikasnost i redukuje ukupne troškove proizvodnje zaštitne odeće. Tekstilni materijali koji su ugrađeni u ovu odeću poseduju dobra fizičko-mehanička svojstava, propustljivi su za vazduh i vodenu paru nakon klimatskih tretmana i tokom praktične upotrebe. Tokom ispitivanja zaštitnih svojstava i karakteristika fiziološke podobnosti određeni su i neki ergometrijski indikatori.

Ključne reči: hemijska zaštita, NHB zaštitna odeća, SaratogaTM materijal, aktivni ugalj, fiziološka podobnost.

Dalje >>>