ZORAN ČAJKA2
Vernadsky Institute of Geochemistry and Analytical Chemistry, Moscow, Russia, University ALFA, Belgrade, Serbia, University Singidunum, FEFA, Belgrade, Serbia
UDC:504.75.05:711.4
doi:10.5937/ZasMat1503251E
Zastita Materijala 56 (3)
251 – 260 (2015)
A city as an urban taxon of the biosphere and a problem of waste
Absract
A number of environmental characteristics of the city as a special biospheric urbanized taxon, including important issues of inventory collection, recycling and the development of closed technological systems are analyzed in this article. Improving solid waste management is one of the most effective ways to strengthen overall municipal management and is usually an important condition for other, more complicated, municipal services. Solid waste is unavoidably linked to urbanization and overall economic development. Today, more than 50 percent of the world’s population lives in cities, and the rate of urbanization is on the rise. By 2050, as many people will live in cities as the population of the whole world in 2000. This will certainly add various challenges to waste disposal. Citizens, corporations, and cities will likely need to assume more responsibility for waste generation and disposal, especially in the area of product design and waste separation.
Keywords: city, garbage, eco system, urbanized taxon, pollution, wastes.
Grad kao urbana klasifikacija biosfere i problem otpada
Izvod
U ovom radu su analizirane ekološke karakteristike grada kao posebno urbanizovane biosfere, uključujući važna pitanja u vezi sa reciklažom i razvojem zatvorenih tehnoloških sistema. Unapređenje upravljanja čvrstim otpadom jedan je od najefikasnijih načina za jačanje sveukupnog gradskog upravljanja i ono predstavlja važan uslov za ostale komplikovanije gradske usluge. Čvrsti otpad je neminovno povezan sa urbanizacijom i sveukupnim ekonomskim razvojem. Danas više od 50% ljudi živi u gradovima i nivo urabanizacije sve više raste. Do 2050. godine više ljudi će živeti u gradovima nego celokupno stanovništvo u svetu u 2000. godini. Ovo će svakako predstavljati dodatne izazove za odlaganje otpada. Stanovništvo, kompanije i gradovi će morati da preuzmu veću odgovornost za stvaranje i odlaganje otpada, posebno u oblasti dizajna proizvoda i odvajanja otpada.
Kjučne reči: grad, đubre, ekosistem, urbanizovana biosfera, zagađenje, otpad.
ROMAN SOWA1,2, ANDRZEJ KOWAL1, ELZBIETA ROGA1, SEBASTIAN ARABASZ3, ANDRZEJ DZIEDZIC4, IRENA DUL5, MAGDALENA PARLINSKA-WOJTAN1
1Facility for Electron Microscopy & Sample Preparation, 2Centre for Microelectronics and Nanotechnology, Department of Mathematics and Natural Sciences, University of Rzeszow, Rzeszow, Poland, 2MTU Aero Engines Polska, Jasionka, Poland, 3Labsoft SA, Warszawa, Poland, 4Centre for Innovation & Knowledge Transfer, University of Rzeszow, Poland, 5WSK PZL-Rzeszow S.A. Rzeszow, Poland
UDC:620.181:669.18-156
doi:10.5937/ZasMat1503261S
Zastita Materijala 56 (3)
261 – 268 (2015)
Influence of double solution treatment on hardness in 17-4 PH steel
Abstract
The investigated material is a corrosion-resistant, Cu precipitation hardened steel 17-4PH, which undergoes a macroscopic contraction, as a result of applying the following heat treatment: double solution treatment at 1028°C for 1 h (condition A), ageing at 540°C for 4 h (condition H1025). The second solution treatment at 1028°C was found to eliminate the retained austenite, being the evidence of a completely finished martensitic transformation. Indeed, the only phase identified in all samples was fcc lath martensite exhibiting a parallel striped structure. Unfortunately, this additional heat-treatment operation leads likewise to significant and irregular grain growth, which consequently causes a drop in material hardness. In addition to the martensitic phase, in the unaged samples, a δ-ferrite phase could be identified by TEM and electron diffraction, which is favorable for ductility and toughness of the material. In all samples, non-coherent fcc-NbC precipitates identified by electron diffraction and EDX mapping having sizes up to 70 nm were found.
Keywords: steel 17-4PH, retained austenite reduction, Cu precipitation hardening, δ-ferrite, NbC precipitates, TEM.
Uticaj dvostrukog tretmana rastvorom na tvrdoću 17-4pH čelika
Izvod
Istraživan je materijal na korozionu otpornost, taloženjem Cu na kaljeni čelik 17-4PH, koja prolazi kroz makroskopsku kontrakciju, kao rezultat primene sledećih tretmana toplotom: dupli tretman rastvorom na 1028°C tokom 1h (uslov A), starenje na 540°C u toku 4h (uslov H1025). Drugim tretmanom rastvorom na 1028°C, utvrđeno je da se eliminiše zaostala austenitna struktura, što kao dokaz imam potpunu martenzitnu transformaciju. Zaista, identifikovana je u svim uzorcima samo faza martenzitne paralelne prugaste strukture. Nažalost, ovaj dodatni toplotni tretman dovodi do značajnog, isto tako i nepravilnog rasta zrna, što posledično dovodi do smanjenja tvrdoće materijala. Pored martenzitne faze, koja nije ostarila na uzorcima, faza δ-ferita može se prepoznati po TEM i elektronskoj difrakciji, što pogoduje duktilnosti i žilavosti materijala. U svim uzorcima, ne-koherentna fcc-NbC precipitacija prepoznaje se po elektronskoj difrakciji i EDX mapiranju zrna do veličine 70mm, koja su pronađena.
Ključne reči: čelik 17-4PH, smanjenje austenitne redukcije, Cu vezivanje, δ-ferit, NbC taloženje, TEM.
1University of Belgrade, Institute of Chemistry, Technology and Metallurgy-Center for Microelectronic Technologies, Belgrade, Serbia, 2University of Belgrade, Faculty of Technology and Metallurgy, Belgrade, Serbia
Indentation behaviour of „soft film on hard substrate“ composite system type
Absract
This investigation has been carried out in order to analyse and compare the hardness response of different composite systems of the same type, named „soft film on hard substrate“ composite system. Composite systems of mono- and multilayered electrodeposited Ni and Cu thin films on (100) and (111)-oriented monocrystalline Si wafers and 100 µm-thick electrodeposited Ni film as the substrates were fabricated.
The indentation behaviour of these composite structures was characterized using Berkovich nanohardness and Vickers microhardness testing.
The measured hardness is so-called „composite hardness“, because the substrate participates in the plastic deformation during the indentation process. The contribution of the substrate to the measured hardness starts at indentation depths of the order of 0.07- 0.2 times the film thickness.
Dependence of nanohardness and microhardness values on electrodeposition process conditions, substrate and film microstructure, total film thickness, layer thickness and Ni/Cu layer thickness ratio for different composite systems ratio was investigated. Composite hardness model of Chicot-Lesage (C-L) was chosen and applied to experimental data in order to determine absolute film hardness.
Keywords: composite hardness, nanohardness, vickers microhardness, hardness model, Ni/Cu electrodeposition, Ni/Cu multilayers
Ponašanje kompozitnih sistema tipa ”mek film na tvrdom supstratu” na testu utiskivanja
Izvod
Ovo istraživanje je izvršeno u cilju analize i upoređivanja odziva različitih kompozitnih sistema koji pripadaju istom tipu sistema nazvanom „mek film na tvrdom supstratu“, pri merenju tvrdoće. Formirani su kompozitni sistemi elektrodepozicijom jedno- i višeslojnih Ni i Cu tankih filmova na (100) i (111)-orijentisanim monokristalnim Si pločicama i 100-µm debelom elektrodeponovanom Ni filmu kao supstratima.
Ponašanje ovih kompozitnih struktura pri utiskivanju je okarakterisano merenjem nanotvrdoće po Berkoviču i mikrotvrdoće po Vikersu.
Izmerena vrednost mikrotvrdoće se naziva „kompozitnom tvrdoćom“ jer prilikom testiranja utiskivanjem dolazi i do plastične deformacije supstrata. Doprinos deformacije supstrata izmerenoj tvrdoći počinje na dubinama utiskivanja koje su reda 0.07-0.2 puta manje od debljine filma.
Istraživana je zavisnost vrednosti nanotvrdoće i mikrotvrdoće od procesnih parametera elektrodepozicije, mikrostrukture supstrata i filmova, ukupne debljine filma, debljine pojedinačnog sloja u filmu i odnosa debljina Ni/Cu pojedinačnih slojeva u filmu za različite kompozitne sisteme. Radi određivanja apsolutne tvrdoće filma u sistemu, odabran je i na eksperimentalne rezultate primenjen model kompozitne tvrdoće Šiko-Lezaž (C-L).
Ključne reči: kompozitna tvrdoća, nanotvrdoća, vikersova mikrotvrdoća, model tvrdoće, Ni/Cu elektrodepozicija, Ni/Cu višeslojni filmovi.
1Prirodno-matematički fakultet, Departman za hemiju, biohemiju i zaštitu životne sredine, Univerzitet u Novom Sadu, Novi Sad, 2Tehnološko-metalurški fakultet, Univerzitet u Beogradu, Beograd, Srbija
Proučavanje fizičko-hemijskih svojstava novosintetisanih derivata uracila
Izvod
Derivati uracila predstavljaju potencijalno biološki aktivna jedinjenja, pa je ispitivanje njihovih fizičko-hemijskih svojstava veoma značajno za njihovu dalju primenu. U ovom radu je ispitana serija novosintetisanih derivata uracila primenom spektrofotometrijske metode. Apsorpcioni spektri su snimljeni u sedamnaest rastvarača različitih svojstava. Uticaj rastvarača na apsorpcione spektre tumačen je primenom Kamlet-Taft-ovog solvatohromnog modela. Dominantnost i vrste interakcija koje se javljaju između ispitivanih derivata i rastvarača analizirane su metodom višestruke linearne korelacije dobijenih vrednosti položaja apsorpcionih maksimuma i Hansen-ovih parametara rastvarača. Pored uticaja rastvarača, tumačen je i uticaj supstituenta prisutnog u molekulu na apsorpcione spektre pomoću Hammett-ove jednačine.
Ključne reči: derivati uracila, solvatohromizam, uticaj supstituenta, spektrofotometrija, korelaciona analiza
Studyng of physicochemical properties of newly synthesized uracil derivatives
Absract
Uracil derivatives are potentially biologically active compounds, so the investigation of their physical and chemical properties is very important for their further application. In this work a series of newly synthesized derivatives of uracile was investigated by applying the spectrophotometric method. The absorption spectra were recorded in seventeen solvents with different properties. The effect of solvent was interpreted by Kamlet-Taft solvatochromic model. The dominance and the types of interactions that occur between the investigated derivatives and solvent were interpreted by applying the multiple linear correlation obtained values of absorption maxima and Hansen’s solvent parameters. In addition to the effect of solvent, the influence of substituents in the molecule on absorption spectra was studied by applying Hammett equation.
Keywords: uracil derivatives, solvatochromism, effect of substituents, spectrophotometry, correlation analysis
1University of Novi Sad, Faculty of Sciences, Department for Chemistry, Biochemistry and Environmental Protection, Novi Sad, Serbia, 2University of East Sarajevo, Faculty of Technology, Zvornik, Republic of Srpska
UDC:531.452(n)
doi:10.5937/ZasMat1503289T
Zastita Materijala 56 (3)
289 – 296 (2015)
Potential application of nanomaterials in the treatment of contaminated sediment
Abstract
In the conducted research nano zero valent iron has been used as the immobilization agent in the remediation treatment of dredged sediment, as well as the treatment that is performed on-site (in-situ). Study aims to find a better understanding of the behavior of metals in sediments and to determine their potential mobility, bioavailability and potential toxicity based on sequential extraction procedures. In order to evaluate the extraction potential of toxic metals and the effectiveness of the treatment applied, three single-step leaching tests were performed. When applying nanomaterial, as the immobilization agent in sediment treatment, using two remediation options (ex – situ and in – situ), high stability of the metals is achieved in treated sediment.
Keywords: kaolinite and bentonite coated nZVI, ex-situ and in-situ remediation, sediment.
Potencijalna primena nanomaterijala u tretmanu kontaminiranog sedimenta
Izvod
U sprovedenom istraživanju je korišćeno nаno, nulа vаlentno, gvožđe kao imobilizacioni agens u tretmanu sedimenta, kаko pri remedijаciji izmuljenog sedimentа, tаko i pri tretmаnu koji se vrši nа sаmoj lokаciji (in-situ). Studija ima za cilj da pronađe bolje razumevanje ponašanja metala u sedimentu i da utvrdi njihovu potencijalnu mobilnost, biodostupnost i potencijalnu toksičnost na osnovu sekvencijalne ekstrakcione procedure. Da bi se procenio potencijal izluživanja toksičnih metala i efikasnost postupka koji se primenjuje, izvedena su tri testa izluživanja u jednom koraku. Primenom nanomaterijala, kao imobilizacionog agensa u tretmanu sedimenta pomoću dve opcije remedijacije (ex-situ i in-situ), postignuta je visoka stabilnost metala u tretiranom sedimentu.
Ključne reči: kaolinit i bentonit stabilizovano nZVI, ex-situ i in-situ remedijacija, sediment.
DRAGANA MEDIĆ, MILAN ANTONIJEVIĆ,
SNEŽANA MILIĆ, MILE DIMITRIJEVIĆ
Tehnički fakultet u Boru, Univerzitet u Beogradu, Bor, Srbija
UDC:620.193.4:669.35
doi:10.5937/ZasMat1503297M
Zastita Materijala 56 (3)
297 – 303 (2015)
Amino kiseline kao inhibitori korozije bakra u 0.05M HCl
Izvod
Povećana zabrinutost stručne i naučne javnosti za očuvanje životne sredine, dovela je do sve veće upotrebe ekološki prihvatljivih inhibitora za zaštitu metala od korozije. U ovom radu ispitivana je mogućnost zaštite bakra od agresivne hlorovodonične kiseline, korišćenjem amino kiselina kao „zelenih inhibitora“. Ispitivane su inhibitorske osobine različitih koncentracija cisteina, metionina i alanina na bakarnoj elektrodi u 0.05M rastvoru hlorovodonične kiseline i to korišćenjem metoda kao što su: merenje potencijala otvorenog kola, linearna voltametrija i ciklična voltametrija. Nađeno je da najbolja inhibitorska svojstva pokazuje cistein pri koncentraciji od 1·10-2mol/dm3.
Ključne reči: amino kiseline, bakar, hlorovodonična kiselina.
Amino acids as copper corrsion inhibitors in 0.05M HCl
Abstract
Increased concern of professional and scientific community for the environment has led to the increased utilization of environmentally friendly inhibitors for the protection of metals from corrosion. This paper investigates the possibility of using various amino acids as “green” corrosion inhibitors for copper in 0.05 M HCl solution. The inhibitory properties of various concentrations of cysteine, methionine and alanine in 0.05 M hydrochloric acid solution on copper electrode have been evaluated, using the following methods: measuring open circuit potential (OCP), linear scan voltammetry (LSV) and cyclic voltammetric techniques (CVs). It has been established that cysteine (1·10-2M) has the best inhibitory potential.
Keywords: amino acids, copper, hydrochloric acid.
DRAGANA GRUJIĆ1, АLEKSANDAR SAVIĆ1, LJILJANA TOPALIĆ-TRIVUNOVIĆ1, SVJETLANA JANJIĆ1, MAJA ČIČA1, MLADEN STANČIĆ1, MARIJA GORJANC2
1Univerzitet u Banjoj Luci, Tehnološki fakultet, Banja Luka, Republika Srpska B&H,
2Univerza v Ljubljani, Naravoslovnotehniška fakulteta, Ljubljana, Slovenija
UDC:677.027.423:687.31/.36
doi:10.5937/ZasMat1503304G
Zastita Materijala 56 (3)
304 – 314 (2015)
Uticaj upotrebe močila kod bojenja biljnim ekstraktima na stepen obojenja pletenina
Izvod
U ovom radu je istraživan uticaj upotrebe močila kod bojenja pletenina, bez i sa prethodnom obradom plazmom, ekstraktima biljke Achillea millefolium L. na stepen obojenja. Za istraživanja su korištene tri pletenine od prirodnih vlakana (100 % pamuk, 100 % bambus, 50 % pamuk/50 % bambus), istih konstrukcijskih karakteristika i približno iste površinske mase. Bojenje pletenina ekstraktima biljke Achillea millefolium L. rađeno je na dva načina, koristeći metodu iscrpljenja kupatila, bez i uz dodatak močila 3% KNaC4H4O6 · 4H2O. Stepen obojenja, različito obrađenih pletenina, ocjenjivan je na osnovu stereomikroskopskih snimaka i CIELAB metodom. Pored ispitivanja stepena obojenja utvrđivano je antimikrobno dejstvo pletenina obrađenih ekstraktima biljke Achillea millefolium L. na bakterije Escherichia coli i Staphylococcus aureus i kvasac Candida albicans koristeći metodu paralelnih linija (AATCC TM 147).
Ustanovljeno je da se kod bojenja pletenina vodenim ekstraktom biljke Achillea millefolium L. uz dodatak 3% KNaC4H4O6 · 4H2O povećava postojanost obojenja nakon pranja u odnosu na pletenine bojene bez dodatka močila. Rezultati ispitivanja antimikrobnog dejstva pletenina obrađenih vodenim ekstraktom su pokazali da je došlo do povećanja antimikrobnog dejstva nakon pranja kod svih ispitivanih pletenina, s obzirom na bakteriju Escherichia coli, koja se ubraja u grupu rezistentnih bakterija.
Ključne riječi: pletenine, bojenje, ekstrakti biljaka, antimikrobna svojstva, plazma
The influence of mordant usage in dyeing of knitted fabrics with plant extracts on its degree of coloration
Absract
In this paper was examined the influence of mordant usage in dyeing of knitted fabrics with plant extracts, with or without plasma pretreatment, on its degree of coloration. Three different fabrics were used (100% cotton, 100% bamboo and 50% cotton/50% bamboo) with same constructional characteristics and roughly with the same surface mass. Knitted fabrics were treated with aqueous plant extract of Achillea millefolium L., by using bath exhaustion method, and with or without 3% KNaC4H4O6 · 4H2O. The degree of coloration of differently treated knitted fabrics was evaluated with CIELAB method and with stereomicroscop.
Antimicrobial properties of knitted fabrics with plant extract of Achillea millefolium L. were tested on Escherichia coli, Staphylococcus aureus and Candida albicans by using parallel streaking method (AATCC TM 147).
It was found that the dyeing of knitted fabrics with aqueous extract of the plant Achillea millefolium L. with addition of KNaC4H4O6 · 4H2O caused an increasement of the color fastness after washing compared to knitted fabric dyed without addition of KNaC4H4O6 · 4H2O. It was also found that the processing with plant extract had a positive impact on Escherichia coli, bacteria known as resistant,but only for knitted fabrics after washing.
Keywords: knitted fabrics, dyeing, plant extracts, antimicrobial properties, plasma treatment.
BILJANA BOBIĆ1, NIKOLA BAJIĆ2, ALEKSANDAR JEGDIĆ, MAJA STEVANOVIĆ, BORE JEGDIĆ1
1NU Institut za hemiju, tehnologiju i metalurgiju, Univerzitet u Beogradu, Beograd, 2Razvojno istraživački centar IHIS, Zemun, Srbija
UDC:620.194.4
doi:10.5937/ZasMat1503315B
Zastita Materijala 56 (3)
315 – 319 (2015)
Određivanje brzine korozije metala šava u zavarenom spoju pomoću elektrohemijskih tehnika
Izvod
Za određivanje brzine korozije osnovnog metala i metala šava u zavarenom spoju primenjene su elektrohemijske tehnike: linearna polarizaciona otpornost, voltametrija sa linearnom promenom potencijala i elektrohemijska impedansna spektroskopija. Uzorci za ispitivanje dobijeni su elektrolučnim zavarivanjem čeličnog kotlovskog lima, uz upotrebu obloženih bazičnih elektroda. Pri zavarivanju je korišćena fabrička elektroda i elektrode koje su proizvedene u laboratorijskim uslovima (tanko obložena i debelo obložena bazična elektroda). Utvrđeno je da je brzina korozije metala šava veća od brzine korozije osnovnog metala. Brzina korozije metala šava dobijenog pomoću tanko obložene elektrode je manja od brzine korozje metala šava dobijenog pomoću debelo obložene i fabričke elektrode. Vrednosti za brzinu korozije, određene različitim elektrohemijskim tehnikama, su u saglasnosti.
Ključne reči: zavareni spoj, korozija, brzina korozije, elektrohemijske metode.
Determination of the weld metal corrosion rate using electrochemical techniques
Absract
To determine corrosion rate of the base metal and weld metal were applied electrochemical techniques: linear polarization resistance, linear sweep voltammetry and electrochemical impedance spectroscopy. The samples were obtained by arc welding steel boiler plate using coated basic electrode. Factory electrode and electrodes, which are produced in the laboratory thinly and thick coated basic electrodes, were used for welding. It was found that the corrosion rate of the weld metal was greater than the corrosion rate of the base metal. The corrosion rate of weld metal obtained by thinly coated electrodes is less than the corrosion rate of weld metal obtained by thick coated basic and factory-coated electrodes. The corrosion rates, determined by different electrochemical techniques are in agreement.
Keywords: welded joint, corrosion, corrosion rate, electrochemical methods.
1Institut za tehnologiju nuklearnih i drugih mineralnih sirovina, Beograd, 2Univerzitet u Beogradu, Poljoprivredni fakultet, Beograd, Srbija
UDC:581.111:634.21
doi:10.5937/ZasMat1503321S
Zastita Materijala 56 (3)
321 – 328 (2015)
Uticaj hemijske modifikacije na adsorpcione karakteristike biosorbenta na bazi koštica kajsija
Izvod
U radu je ispitan uticaj hemijske modifikacije, primenom NaOH, na strukturne promene lignoceluloznog ostatka koštica kajsije (KK) i na adsorpcioni kapacitet biomaterijala prema jonima bakra. Biomaterijal pre i posle hemijskog tretman ispitan je skenirajućom elektronskom mikroskopijom (SEM) i Furijeovom transformacionom infracrvenom spektroskopijom (FTIR). SEM je pokazao da nakon hemijskog tretmana struktura materijala je rapavija kao posledica uklanjanja voska, masti i ostalih nečistoća i pristupačnija molekulima vode i jonima bakra. FTIR analiza je pokazala da pik koji se kod prirodnog materijala javlja na 1735 cm-1 (ukazuje na valencionu vibraciju –C=O veze, koja potiče od karboksilnih grupa ili estra ili voskova i masti) kod modifikovanog materijala je značajno redukovan. Određivanjem tačke nultog potencijala utvrđeno je da je posle modifikacije došlo do promene naelektrisanja površine materijala (pHpzc kod KK je 4,9 a kod KKM je 6,0).
Kao posledica tretmana, promene koje su se dogodile uslovile su pet puta veči adsorpcioni kapacit kod modifikovanog (10,8 mg/g) u odnosu na prirodni biomaterijal (2,5 mg/g).
Ključne reči: lignocelulozni materijali, koštice kajsije, biosorpcija, bakar, hemijska modifikacija
Effect of chemical treatment on adsorption characteristics of apricot stone biosorbent
Abstract
This paper deals with investigation of alkali treatment effect on structural changes of apricot stones lingo-cellulosic residue (KK) and on adsorption capacity based on adsorption of Cu(II) ions from wastewater. Characterization of natural and alkali treated biomaterial were done by FT-IR and SEM. SEM micrographs showed that the removal of the surface impurities after treatment, improves the surface roughness of KK thus opening more hydroxyl groups and other reactive functional groups on the surface. FT-IR spectrum showed that the peak at 1735 cm-1 from of untreated KK, which is assigned to aromatic carbonyl or carboxyl C=O stretching of carboxylic acids or their esters, was reduced after treatment. After treatment change of point of zero charge value of modified biomaterial was evident: from pHPzc=4.9 (KK) to pHPzc=6.0 (KKM). Overall, the changes made by alkali treatment of KK, resulted in five times higher adsorption capacity.
Keywords: lingocellulosic material, apricots, biosorption, copper, chemical modification
1University of Belgrade, Innovation Centre of Faculty of Mechanical Engineering, Belgrade, Serbia, 2University of East Sarajevo, Faculty of Technology, Zvornik, Republic of Srpska, 3Academy of Sciences and Arts of Republic of Srpska, Banja Luka, B&H
UDC:620.92(n)
doi:10.5937/ZasMat1503329H
Zastita Materijala 56 (3)
329 – 334 (2015)
Nanomaterials and nanotechnology for sustainable energy
Abstract
The use of nanotechnology to develop a suite of sustainable energy production schemes is one of the most important scientific challenges of the 21st century. The challenge is to design, to synthesize, and to characterize new functional nanomaterials with controllable sizes, shapes, and/or structures.
Nanotechnology is generating a lot of attention these days and therefore building great expectations not only in the academic community but also among investors, the governments, and industry. This paper, explores some of the possible implementations of nanotechnology for new and improved methods of energy conversion, considering a need for this to be done without compromising our environment. Its unique capability to fabricate new structures at atomic scale has already produced novel materials and devices with great potential applications in a wide number of fields. Focus is given to important role of nanomaterials, preparation and characterization some of nanomaterials important for sustainable energy, dye sensitized solar cels and hydrogen production technology.
Key words: solar energy, energy conversion, dye sensitized solar cels, hydrogen
Nanomaterijali i nanotehnologije za proizvodnju održive energije
Izvod
Upotreba nanotehnologija u cilju razvijanja načina proizvodnje održive energije je jedan od najznačajnijih izazova 21 veka. Izazov je dizajnirati, sintetizovati i izvršiti karakterizaciju novih funkcionalnih nanomaterijala kontrolisanih veličina, oblika i/ili struktura. Nanotehnologija danas privlači punu pažnju ne samo akademske zajednice, već i investitora, vlada i privrede a radi izgradnje i ostvarivanja velikih očekivanja.
Ovaj rad istražuje moguću primenu nanotehnologija za nove i unaprijeđene metode pretvaranja energije, uvažavajući potrebe naše sredine. Njihova je jedinstvenost u tome što imaju mogućnost da fabrikuju nove structure na atomskom nivou, kao što su već proizvedeni novi materijali i uređaji sa mogućnošću visoko potencijalne primene u mnogo oblasti. Fokus je na bitnoj ulozi nanomaterijala, pripremi i karakterizaciji nekih nanomaterijala za proizvodnju održive energije, tankoslojnih solarnih ćelija u tehnologiji proizvodnje energije vodonikom.
Ključne riječi: solarna energija, konverzija energije, tankoslojne solarne ćelije, vodonik
SANJA Ž. GRBAVČIĆ1, DUŠAN Ž. MIJIN2, ZORICA D. KNEŽEVIĆ-JUGOVIĆ2
1University of Belgrade, Innovation Center of Faculty of Technology and Metallurgy, Belgrade, Serbia, 2University of Belgrade, Faculty of Technology and Metallurgy, Belgrade, Serbia
UDC:635.11:664.039
doi:10.5937/ZasMat1503335S
Zastita Materijala 56 (3)
335 – 339 (2015)
Immobilization of peroxidase from fresh horseradish extract for anthraquinone dye decolorization
Abstract
Synthetic dyes are used in all sectors of industry and represent a serious ecological problem. By the presence, anthraquinone dyes are right after the azo dyes. Unlike azo, anthraquinone dyes are considerably harder to degrade due to the presence of coupled aromatic rings in their structure. Horseradish peroxidase (HRP) proved to be an efficient and ecologically acceptable solution for synthetic dyes decolorization. For that reason, feasibility of peroxidase from fresh horseradish extract application in anthraquinone dye decolorization was the object of this research. Unpurified peroxidase (1.5 mg mL-1), was immobilized onto fumed silica by adsorption. In order to optimize the decolorization of anthraquinone dye Acid Violet 109 (AV 109) 0.1 IU of obtained immobilized HRP was applied in a batch reactor. Under the optimal conditions (pH 4.0, dye concentration 30 mg L-1, hydrogen peroxide concentration 0.1 mM) 55.1 % of initial dye concentration was decolorized, within 30 min. In addition, compared to free enzyme, immobilized HRP showed higher resistance towards inhibitory influence of the dye and hydrogen peroxide.
Keywords: horseradish peroxidase, immobilization, dye, wastewater.
Imobilizacija peroksidaze iz svežeg ekstrakta rena i primena u dekolorizaciji antrahinonskih boja
Izvod
Sintetičke boje se primenjuju u gotovo svim granama u industriji i predstavljaju ozbiljan ekološki problem. Po zastupljenosti, antrahinonske boje se nalaze na drugom mestu, odmah posle azo boja. Za razliku od azo boja, antrahinonske boje se zbog prisustva kondenzovanih aromatičnih prstenova teže razgrađuju. Peroksidaza iz rena se pokazala kao efikasno i ekološki prihvatljivo rešenje za dekolorizaciju sintetičkih boja. Iz tog razloga je predmet ovog rada mogućnost primene neprečišćene peroksidaze iz svežeg ekstrakta rena u dekolorizaciji antrahinonskih boja. Neprečišćena peroksidaza (1.5 mg mL-1) imobilisana je adsorpcijom na silikatne čestice. 0.1 IU dobijene imobilisane peroksidaze je upotrebljena u cilju optimizacije dekolorizacije antrahinonske boje AV 109 u šaržnom reaktoru. Pod optimizovanim uslovima (pH 4.0, koncentracija boje 30 mg L-1, koncentracija vodonik-peroksida 0.1 mM, vreme kontakta 40 minuta), 55.1 % ispitivane boje je uklonjeno. Pored toga, imobilizacijom je značajno umanjen inhibitorni uticaj boje i peroksida na peroksidazu.
Ključne reči: peroksidaza iz rena, imobilizacija, boje, otpadna voda.
SAŠA ZELJKOVIĆ1, JELENA PENAVIN ŠKUNDRIĆ1, DIJANA JELIĆ2, SLAVICA SLADOJEVIĆ3, LJUBICA VASILJEVIĆ4
1University of Banja Luka, Faculty of Science and Mathematics, Banja Luka, Bosnia and Herzegovina.
2University of Banja Luka, Medical Faculty – Pharmacy department, Banja Luka, Bosnia and Herzegovina,
3University of Banja Luka, Faculty of Technology, Banja Luka, Bosnia and Herzegovina,
4University of East Sarajevo, Faculty of Technology Zvornik, Zvonik, Bosnia and Herzegovina
UDC:628.316.13
doi:10.5937/ZasMat1503340Z
Zastita Materijala 56 (3)
340 – 344 (2015)
Interaction of hexavalent chromium and BSCF perovskite in water solutions
Abstract
In this study, interaction of BSCF perovskite and hexavalent chromium in the aqueous solution was followed to provide additional useful insight in chemistry and behavior of this material.
Adsorption experiments were carried out systematically by batch experiments to investigate the influence of contact time, temperature and initial concentration of metal ions. The adsorption data obtained were described by the Freundlich and Langmuir adsorption isotherm model.
Thermodynamic study of hexavalent chromium adsorption on BSCF perovskite showed that the spontaneous adsorption process will be favored at higher temperatures (from 343 K) depending on the chromium concentration in water.
Keywords: BSCF, perovskite, adsorption, chromium.
Interakcija heksavalentnog hroma i BSCF perovskita u vodenoj sredini
Izvod
U ovoj studiji je praćena interakcija BSCF perovskita i heksavalentnog hroma u vodenoj sredini kako bi se obezbijedile korisne informacije o hemizmu i ponašanju ovog materijala.
Eksperimenti adsorpcije su izvedeni sistematično i u serijama kako bi se ispitali uticaji dužine kontakta, temperature i inicijalne koncentracije metalnih jona. Podaci su opisani Freundlichovim i Langmuirovim adsorpcionim modelom.
Termodinamička studija adsorpcije heksavalentnog hroma na BSCF perovskitu pokazala je da je spontani proces adsorpcije favorizovan pri višim temperaturama (od 343K) zavisno od koncentracije hroma u vodenoj sredini.
Ključne riječi: BSCF, perovskit, adsorpcija, hrom.
GORDANA TOPLIČIĆ-ĆURČIĆ, DUŠAN GRDIĆ, NENAD RISTIĆ, ZORAN GRDIĆ
University of Nis, Faculty of Civil Engineering and Architecture, Nis, Serbia
UDC:666.94.4:693.75
doi:10.5937/ZasMat1503345T
Zastita Materijala 56 (3)
345 – 353 (2015)
Properties, materials and durability of rolled compacted concrete for pavements
Absract
Roller-Compacted Concrete (RCC) consists of an engineered mixture of dense-graded aggregates, cement and water. This zeroslump concrete mixture, when placed with an asphalt paver and compacted to high density, provides a high-strength, durable pavement structure. RCC uses no forms, requires no conventional finishing, and needs no dowels or reinforcing steel, making it an economical choice. The low water-cement ratio (usually ranging from 0.30 to 0.40) provides for very high strengths. Common design unconfined compressive strengths for pavements are in the range of 35 to 55 MPa. With the low water-cement ratio there is less paste in the concrete matrix, so there is no bleed water and less shrinkage than in conventional PCC.In the past 30 years it has gained acceptance as a strong and durable pavement material that can withstand heavy loads and severe climates with little required maintenance.
Keywords: roller-compacted concrete, pavement, properties, materials, durability.
Svojstva, materijali i trajnost valjanog betona za kolovoz
Izvod
Valjani beton (RCC) je projektovana betonska mešavina koja se sastoji od zbijenog separisanog agregata, cementa i vode. Ova betonska mešavina čija je vrednost sleganja nula, prilikom ugrađivanja sa asfaltnim finišerom i kada je sabijena do velike gustine, daje veoma čvrstu i trajnu kolovoznu konstrukciju. Za RCC se ne koriste oplate, nije potrebna konvencionalna završna obrada i ne koriste se dilatacione razdelnice ili armaturni čelik, što ga čini ekonomičnim. Mala vrednost vodocementnog faktora (obično se kreće od 0,30 do ,0,40) obezbeđuje veliku čvrstoću. Uobičajene projektovane vrednosti čvrstoće pri pritisku nalaze se u opsegu od 35 do 55 N/mm2. Zbog male vrednosti vodocementnog faktora i manje količine paste u betonskoj matrici, ne dolazi do „krvarenja“ betona, osim toga, skupljanje je manje nego kod konvencionalnih betona od portland cementa. U proteklih 30 godina, prihvaćen je kao jak i trajan kolovozni materijal koji može da izdrži velika opterećenja i oštru klimu uz malo potrebnog održavanja.
Ključne reči: valjani beton, kolovoz, svojstva, materijali, trajnost.
VLADAN MIĆIĆ21University of Kosovska Mitrovica, Faculty of technical science, Kosovska Mitrovica, Serbia
2University of East Sarajevo, Faculty of Technology, Zvornik, Republic of Srpska, B&H
UDC:65.012.261.001.26
doi:10.5937/ZasMat1503354P
Zastita Materijala 56 (3)
354 – 366 (2015)
Optimization of dimension of weldment locus by method of geometric programming
Abstract
This paper, on the example of a typical loaded welded assembly, made optimization of its dimensions in terms of the cost of welding. In such an elaboration the mathematical optimization model with limitation functions has also been presented and it should be taken into account in the process of designing by the technologist and designer.
To solve the presented problem the method of geometric programming was proposed that has in detail been elaborated in the paper in the form of an algorithm suitable for the application. In this way the optimization or primary task was reduced to a dual task through a proper function, which is much easier to solve.
The method has been illustrated on a practical computational example with a different number of limitation functions. It is shown that in case of a lower degree of complexity the solution can be reached by maximizing the corresponding dual function by means of mathematical analysis. In case of a higher degree of complexity, it is necessary to use some of the methods of non-linear programming. In this case the solution of the problem is simplified due to the minimization of a linear equation.
Keywords: Alphabetic loaded welded structures , the mathematical model of optimization, the cost function , feature limitations , geometric programming, positive polynomials, dual function.
Optimizacija dimenzija opterećenog zavarenog sklopa metodom geometrijskog programiranja
Izvod
U radu je na primeru jednog karakterističnog opterećenog zavarenog sklopa izvršena optimizacija njegovih dimenzija sa aspekta troškova zavarivanja. Pri ovome, postavljen je matematički model optimizacije sa finkcijama ograničenja koje pri projektovanju moraju uzeti u obzir tehnolog i konstruktor.
Za rešavanje postavljenog problema, predložen je metod geometrijskog programiranja koji je detaljno razrađen u radu u obliku algoritma pogodnog za primenu.Na taj način optimizacioni ili primarni zadatak, sveo se na dualni zadatak preko odgovarajuće funkcije, koji se znatno lakše rešava.
Metod je ilustrovan na jednom računskom praktičnom primeru sa različitim brojem funkcija ograničenja. Pokazano je da se za slučaj manjeg stepena složenosti do rešenja može doći maksimizacijom odgovarajuće dualne funkcije primenom matematičke analize. Za slučaj većeg stepena složenosti, neophodna je primena neke od metoda nelinearnog programiranja. U ovom slučaju rešenje problema je pojednostavljeno zbog svođenja linerane jednačine.
Ključne riječi: zavarene strukture po abecednom redosledu, matematički model optimizacije, funkcija troškova, karakteristična ograničenja, geometrijsko programiranje, pozitivni polinomi, dvostruka funkcija.
2Visoka tehnološka škola strukovnih studija, Sabac, Srbija
Distribucija kobalta u procesu hidrometalurške proizvodnje cinka
Izvod
Hidrometalurška proizvodnja cinka zasnovana je na preradi sulfidnih koncentrata koji, pored cinka, sadrže i veliki broj drugih metala, koji su redovni pratioci cinka u njegovim rudama. Najčešće to su olovo, bakar, kadmijum, kobalt, nikal, antimon i neki drugi, a sadržaj ovih metala varira u zavisnosti od porekla rude. Mogućnost eksploatacije kobalta prisutnog u sulfidnim koncentratima cinka zavisi od konkretnih sadržaja u sirovini i od toga na koji se način ovaj metal distribuira u okviru procesa, tj. da li se, gde, i u kojoj meri koncentriše. U radu je na bazi sistematskog analitičkog praćenja kobalta u rastvorima i talozima iz procesa utvrđena distribucija kobalta u hidrometalurškom procesu proizvodnje cinka. Konstatovano je da se glavna količina prisutnog kobalta sakuplja u jednom od otpadnih talogu iz proizvodnje kadmijuma, i da se u ovom talogu sadržaj kobalta kreće oko 0,85%, dok su sadržaji kobalta u drugum rastvorima i talozima neuporedivo manji. Sa ovim sadržajima kobalta, talog od prečišćavanja kobalta, koji nastane u toku godine u hidrometalurškom procesu proizvodnje cinka u fabrici u Šapcu, predstavlja komercijalno značajan resurs kobalta.
Ključne reči: hidrometalurška proizvodnja cinka, distribucija kobalta
Cobalt distribution in the process of hydrometallurgical zinc production
Abstract
Hydrometallurgical zinc production is based on processing sulphide concentrates which, beside zinc, contain a large number of other regular accompanied metals in zinc ores. Those are, usually, lead, cadmium, cobalt, nickel, antimony and some other, and the content of these metals vary depending on ore origin. The possibility of cobalt exploitation presented in sulphide zinc concentrates depends on specific contents in raw material, as well as the way this metal is distributed during the process, i.e. if it is concentrated, where and to which extent. In this paper, based on systematic analytical cobalt monitoring in solutions and precipitates,cobalt distribution in the process of hydrometallurgical zinc production is determined. It was stated that the main quantity of presented cobalt is collected in the treated cobalt precipitate out of cadmium production, that the precipitate contains about 0,85% of cobalt, while the contents of cobalt in other solutions and precipitates are uncomparable less. With these cobalt contents, the precipitate from cobalt treatment that is obtained in the course of the year in the process of hydrometallurgical zinc production in the factory in Šabac means commercially significant cobalt resource.
Keywords: hydrometallurgical zinc production, cobalt distribution.
ZORICA KOVAČEVIĆ3, DRAGAN GUSKOVIĆ4 1PERIĆ&PERIĆ&Co. d.o.o., Požarevac, Srbija,
2Visoka tehnička škola strukovnih studija, Beograd, Srbija, 3Institut za ispitivanje materijala, Beograd, Srbija, 4Univerzitet u Beogradu, Tehnički fakultet u Boru, Bor, Srbija
UDC:620.187:669.215
doi:10.5937/ZasMat1503373P
Zastita Materijala 56 (3)
373 – 377 (2015)
Skenirajuća elektronska mikroskopija legure zlata Au585Ag90Cu264Zn61 za proizvodnju nakita
Izvod
Legure zlata ,,585”,koje se koriste za proizvodnju nakita mogu da budu tro-, četvoro-, peto-, i više komponentne legure. Sve ove legure su u osnovi Au-Ag-Cu, sa konstantnom količinom zlata, shodno važećim zakonskim propisima, od 58,5 mas.%Au, dok ostale komponenete zavise od drugih potreba: čvrstoća, plastičnost, boja, specijalni efekti, itd. Ispitivanje je rađeno sa legurama žute boje (Au-Ag-Cu-Zn) i bele boje (Au-Ag-Cu-Zn-Pd), shodno potrebama i zahtevima tržišta u okruženju, gde je i rađeno ispitivanje, tj. u Republici Srbiji.
Starenjem kod legura plemenitih metala, posebno kod legura plemenitih metala sa komponentama koje kristališu po površ.c.k. rešetki, u određenim uslovima predhodne obrade, kao i temperature i vremena starenja, dolazi do termodinamički stabilnog stanja legure, a pritom i do pojave fenomena povećanja tvrdoće i čvrstoće proizvoda.
Ispitivanje strukture proizvoda, kao i promene nastale unutar strukture samog materijala obavlja se različitim mehaničkim i metalografskim metodama. Jedna od najboljih metoda sagledavanja promena u strukturi materijala je ispitivanje skenirajućim elektronskim mikroskopom.
U radu će biti prikazani rezultati ispitivanja legure Au585Ag90Cu264Zn61 – ,,žuto zlato”, skenirajućim elektronskim mikroskopom – SEM. Pored strukture materijala, biće prikazana i hemijska mikroanaliza, dobijena pomoću uređaja – detektora za energo disperzionu spektroskopiju – EDS, pomoću koje se može odrediti distribucija i raspored elementa u jednom kristalnom zrnu.
Ključne reči: legura zlata 585/1000, otvrdnjavanje starenjem, SEM, EDS, mikrostruktura, distribucija elemenata, kristalizacija;
Scaning electron microscopy of gold alloy Au585Ag90Cu264Zn61 for jewel production
Abstract
Gold alloys “585” that are used for production of jewelry can be three-, four-, five- and more component alloys. All these alloys are with Au-Ag-Cu base, with constant amount of gold, according to applicable legislation, of 58.5 mass.% Au, while the other components depend on other needs: hardness, plasticity, color, special effects, etc. The investigation was conducted with alloys of yellow color (Au-Ag-Cu-Zn) and of white color (Au-Ag-Cu-Zn-Pd), according to needs and demands of market environment, where the investigation took place, and that is in The Republic of Serbia.
With age-hardening in alloys of noble metals, especially in alloys of noble metals with components that crystallize with f.c.c. lattice in certain conditions of previous treatment, as well as temperature and period of ageing, a thermodynamic stabile state of alloy appears, and also a phenomena of hardness and strength of product.
The examination of structure of the product, as well as of changes inside the structure of material itself is performed by different mechanic and metallographic methods. One of better methods of overview of changes inside the material structure is examination by scanning electronic microscope – SEM. Beside the structure of material, chemical analysis obtained using the device – detector for energy dispersive spectroscopy – EDS, by which distribution and disposition of elements in one chrismal grain can be determined.
Keywords: gold alloy 585/1000, age-hardening, SEM, EDS, microstructure, distribution of elements, crystallization.
