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Zaštita materijala 4. 2018

IN MEMORIAM

Professor Assoc. Jozefita Marku

Our dearest and unforgettable colleague Mrs. Jozefita Marku was lecturer at the Faculty of Natural Sciences of the University of Tirana until she passed away on 25th of October 2015.

Although her academic and scientific activity was interrupted too early by a sudden incurable disease, her legacy is rich in both fields of her activity.

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IN MEMORIAM

Professor Assoc. Jozefita Marku

Naša poštovana koleginica prof. dr Jozefita Marku bila je predavač na Prirodno-matematičkom fakultetu Sveučilišta u Tirani, do 25. oktora 2015. godine. Iako je njena akademska i naučna aktivnost prerano prekinuta, njeno nasleđe je veoma bogato na oba polja aktivnosti.

Na akademskom polju, kroz predavanja koja je izvodila i drugim nastavnim aktivnostima uvek je iznosila savremena saznanja o temama o kojima je pričala. Njeni studenti su cenili njenu kompetentnost i jasnost u izlaganju predmeta, i jednako su cenili njenu posvećenost i brigu kako bi izazvala njihovu pažnju i želju da budu uključeni i da se bave naučnim radom.

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Aurel Nuro*, Elda Marku, Bledar Murtaj

Tirana University, Faculty of Natural Sciences, Chemistry Department, Tirana, Albania

Scientific paper
ISSN 0351-9465, E-ISSN 2466-2585
UDC:628.4.113.161(282)(496.5)
doi:10.5937/zasmat1804475N


Zastita Materijala 59 (4)
475 – 483 (2018)

Organochlorine pesticides and their residues in surface waters of Albania

Abstract

This study presents concentrations of organochlorine pesticides and their residues in some water ecosystems of Albania. The water samples were collected in three ports of Adriatic Sea (Ports of Vlora, Durres and Porto-Romano), in four rivers (Semani, Shkumbini, Erzeni and Mati rivers) and two main lagoons of Albania (Karavasta and Patoku lagoons). 117 water samples were analyzed for a two years period (March 2014 – April 2016). Qualitative and quantitative analyze of 31 organochlorine pesticides and their residues based on EPA 8081B Method were realized using technique of gas chromatography with electron capture detector. RTX-5 capillary column was used for separation of organochlorine compounds.

The higher concentrations of organochlorine pesticides were found for water samples of Shkumbini River, Semani River and Karavasta Lagoon because of their previous use. Residues of pesticides were in higher level than pesticides because degradation processes. Some individual pesticides were found in higher concentrations in some stations. This could be because of punctual sources or recent use for these pesticides. Organochlorine pesticides concentrations were found to be in lower levels than reported data on previous studies for the same stations.

Keywords: Organochlorine pesticides; Adriatic Sea; Albanian rivers; lagoons; water analyze; GC/ECD.

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ORGANOHLORNI PESTICIDI I NJIHOVI REZIDUALI U POVRŠINSKIM VODAMA ALBANIJE

Izvod

Ova rad istražuje koncentracije organohlornih pesticida i njihovih reziduala u nekim vodnim ekosistemima u Albaniji. Uzorci vode sakupljeni su u tri luka Jadranskog mora (Luke Vlora, Drač i Porto-Romano), u četiri reke (reke Semani, Shkumbini, Erzeni i Mati) i dve glavne lagune Albanije (lagune Karavaste i Patoku). 117 uzoraka vode analizirano je za period od dve godine (mart 2014 – april 2016). Kvalitativna i kvantitativna analiza 31 organohlornih pesticida i njihovi ostataka, na bazi EPA 8081B Metoda, su realizovani korišćenjem tehnike gasne hromatografije sa detektorom detektovanja elektrona. RTKS-5 kapilarna kolona je korišćena za razdvajanje organohlornih jedinjenja.

Veće koncentracije organohlornih pesticida pronađene su za uzorke vode reka Shkumbini i Semani i Karavasta laguna zbog njihove prethodne upotrebe. Reziduali pesticida bili su na višem nivou od pesticida jer predstavljaju ostatke procesa degradacije pesticida. Neki pojedinačni pesticidi su pronađeni u većim koncentracijama na nekim stanicama. To može biti zbog tačnih izvora ili nedavne upotrebe ovih pesticida. Utvrđene koncentracije organohlornih pesticida su na nižim nivoima od prijavljenih podataka iz prethodnih ispitivanja za iste stanice.

Ključne reči: organohlorni pesticidi; Jadransko more; Albanske reke; lagune; analiza vode; GC/ECD.

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Milanka Điporovic-Momčilović, Mlađan Popović*, Jasmina Popović, Ivana Gavrilović-Grmuša, Fadhil Hamid, Ahmad Hakky Mohamad

University of Belgrade, Faculty of Forestry, Belgrade, Serbia

 

Scientific paper
ISSN 0351-9465, E-ISSN 2466-2585
UDC:504.75:725.21/.26(497.11)
doi:10.5937/zasmat1804484D

Zastita Materijala 59 (4)
484 – 488 (2018)

Quality of the particleboards on serbian market in regard to the formaldehyde emission

Abstract

The formaldehyde potential of particleboards imported on Serbian market was evaluated in this research. The sampling and testing of particleboards were conducted in two discrete periods: first was during 2011 and the second was in the period of 2015-2016. For both periods, the samples of raw particleboards originated from three different producers. The perforator method (EN 120) was used to test the formaldehyde content in the particleboard samples. In general, the results have showed that the majority of the samples belong to the E1 class of particleboards. In addition, 19 % of the particleboards sampled in 2011 and 31 % of the boards sampled in 2015-2016 were found to have formaldehyde content below 50 % of E1 class requirements.

Keywords: particleboards, formaldehyde, emission class, perforator.

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KVALITET PLOČA IVERICA NA TRŽIŠTU SRBIJE U POGLEDU EMISIJE FORMALDEHIDA 

Izvod

U ovom radu istražen je trend kretanja emisije formaldehida iz ploča iverica uvezenih na tržište Srbije. Uzorkovanje i ispitivanje ploča iverica obavljeno je u dva vremenski odvojena perioda. Prvi period ispitivanja odvijao se tokom 2011. godine, a drugi tokom 2015-2016. godine. U oba ova perioda, uzorkovane su sirove ploče iverice, poreklom od tri različita proizvođača. Perforator metoda (EN 120) korišćena je za ispitivanje sadržaja formaldehida u uzorcima ploča. Rezultati pomenutih ispitivanja pokazali su da velika većina uzoraka pripada E1 klasi ploča iverica. Pored toga, oko 19 % ploča iverica uzorkovanih u 2011. godini i oko 31 % ploča uzorkovanih tokom perioda 2015-2016. godine imali su sadržaj formaldehida ispod 50 % od zahteva za E1 klasom.

Ključne reči: ploča iverica, formaldehid, emisiona klasa, perforator.

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Mihailo Mrdak1*, Časlav Lačnjevac2, Marko Rakin3, Nikola Bajić4

1Research and Development Center, IMTEL Communications a.d.,
Belgrade, Serbia, 2University of Belgrade, Faculty of Agriculture, Belgrade, Serbia, 3University of Belgrade, Faculty of Technology and Metallurgy, Belgrade, Serbia, 4Techno experts d.o.o – Research and Development Center, IHIS, Belgrade, Serbia

Scientific paper
ISSN 0351-9465, E-ISSN 2466-2585
UDC:669.294.86
doi:10.5937/zasmat1804489M


Zastita Materijala 59 (4)
489 – 494 (2018)

Characterization of tantalum coatings deposited using vacuum plasma spray process

Abstract

Tantalum is a very popular material for the industry as a whole because of very important characteristics such as: high melting point, significant thermal and electrical conductivity, high toughness and resistance to corrosion and good biocompatibility. Since the tantalum metal is sensitive to O, N and H gases, tantalum coating layers are deposited only using the vacuum plasma spray process (VPS), which has, in the past few years been used successfully for preparing coatings which are widely used in the preparation of metal implants.

The aim of this paper was to, at a low pressure inert gas eliminate the influence of the surrounding atmosphere on the melted Ta powder particles and produce coatings with mechanical and structural characteristics which will find application in biomedicine. For depositing the coating a commercial tantalum powder AMPERIT® 151065 grain size of 10 – 30 μm was used. The powder was deposited with a plasma F4 gun at a distance of substrates at 300 mm. The Ta coating layers were deposited with a thickness of 60 to 70 μm on steel substrates. As the plasma gas used was a mixture of Ar and He inert gases.

The microhardness of the coating was tested using the HV0.3 method and the tensile strength of the coatings bond was tested by the tensile method in accordance with the ASTM C633-1 standard. The microstructure of the coating in deposited state and after etching was studied on an optical microscope (OM) and scanning electron microscope (SEM). Etching the coating was carried out in the reagent which consisted of two parts of nitric acid, two parts hydrofluoric acid, and five parts water (2HNO3: 2HF: 5H2O). The structure of the coating consists solely of a tough α-Ta phase with a body centered cubic lattice. Tests have shown that layers of VPS – Ta coatings have the microstructure and mechanical properties which completely support the use of the coating in the process of making implants.

Keywords: tantalum coating, mechanical properties, vacuum, microhardness, phases, characteristics, strength.

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KARAKTERIZACIJA TANTAL PREVLAKE DEPONOVANE VAKUUM PLAZMA SPREJ PROCESOM

Izvod

Tantal je veoma atraktivan materijal za industriju u celini zbog veoma bitnih osobina kao što su: visoka temperatura topljenja, značajna toplotna i električna provodljivost, visoka žilavost i otpornost na koroziju i dobra biokompatibilnost. Pošto je tantal metal osetljiv na gasove O, N i H, slojevi prevlake tantala se isključivo deponuju vakuum plazma sprej procesom (VPS), koji se u poslednjih nekoliko godina uspešno koristi za izradu prevlaka koje imaju široku primenu u izradi metalnih implanata.

Cilj rada bio je da se na niskom pritisku inertnog gasa eliminiše uticaj okolne atmosfere na istopljene čestice praha Ta i proizvedu prevlake mehaničkih i strukturnih karakteristika koje će naći primenu u biomedicini. Za deponovanje prevlake koristio se komercijalni prah tantala AMPERIT® 151.065 granulacije od 10 – 30µm. Prah je deponovan sa plazma pištoljem F4 na odstojanju podloge od 300 mm. Slojevi Ta prevlaka su deponovani sa debljinom od 60 do 70µm na čeličnim podlogama. Kao plazma gas koristila se mešavina inertnih gasova Ar i He.

Mikrotvrdoća prevlake ispitana je metodom HV0.3 a zatezna čvrstoća spoja prevlake ispitana je metodom na zatezanje u skladu sa standardom ASTM C633-1. Mikrostruktura prevlake u deponovnom stanju i u stanju posle nagrizanja ispitana je na optičkom mikroskopu (OM) i na skening elektronskom mikroskopu (SEM). Nagrizanje prevlake sprovedeno je u reagensu koji se sastojao od dva dela azotne kiseline, dva dela fluorovodonične kiseline i pet delova vode (2HNO3 : 2HF : 5H2O). Struktura prevlake se isključivo sastoji od žilave α-Ta faze sa zapreminski centriranom kubnom rešetkom. Ispitivanja su pokazala da slojevi VPS – Ta prevlake imaju mikrostrukturu i mehaničke karakteristike koje u potpunosti omogućavaju primenu prevlake u procesu izrade implanata.

Ključne reči: tantal, prevlaka, mehanička svojstva, vakuum, mikrotvrdoća, faze, svojstva, čvrstoća.

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Jovana Galjak, Jelena Djokic, Srdjan Jovic*

1University of Priština, Faculty of Technical Sciences, Kosovska Mitrovica, Serbia

Scientific paper
ISSN 0351-9465, E-ISSN 2466-2585
UDC:379.844/.845
doi:10.5937/zasmat1804495G

Zastita Materijala 59 (4)
495 – 500 (2018)

Prediction of visitors’ thermal comfort in open urban areas

Abstract

Thermal sensation of visitors could be important indicator for urban spaces based on physiological, psychological and behavioural conditions of the visitors. Therefore in this article thermal comfort of the visitors in open urban spaces was investigated. For such a purpose physical data and questionnaire study were used. In order to estimate the optimal conditions in the open urban areas there is need to perform prediction of the thermal comfort and thermal comfort in the areas. The prediction results could be used for optimal arrangement in the open urban areas based on thermal comfort of the visitors. Results of three methods were compares and analysed. The methods are based on artificial intelligence principle.

Keywords: Thermal comfort; Urban square; Neural network; Microclimatic.

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PREDIKCIJA TERMALNOG KONFORA U OTVORENIM URBANIM POVRŠINAMA  

Izvod

Termalna osećajnost od strane posetilaca i turista je važan indicator za urbane površine na osnovi fizioloških, psiholoških i uslova ponašanja turista. Prema tome u ovom radu je analiziran termalni komfor posetilaca i turista u otvorednim urbanim površinama. Za tu svrhu su korišćeni fizički podaci kao anketa među turistima i posetiocima. Kako bi bili postignuti optimalni uslovi u otvorenim urbanism površinama potrebno je uraditi predikciju termalnog komfora u tim površinama. Rezultati poredikcije se mogu potom koristiti za optimalni aranžman u otvorenim urbanism površinama. Rezultati su dobijeni pomoću tri metode. Te metode su bazirane na osnovu veštačke inteligencije.

Ključne reči: termalni komfor; urbana površina; neuronska mreža; mikroklima

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Liljana Kola1*, Pranvera Lazo2

1University of Tirana, Institute of Applied Nuclear Physics, Albania, Rr. ‘Thoma Filipeu’, Qesarakë, Tirana, Albania, 2University of Tirana, Albania, Department of Chemistry, Faculty of Natural Sciences, Blv ‘Zogu I parë’, Tirana, Albania

Scientific paper
ISSN 0351-9465, E-ISSN 2466-2585
UDC:628.161.2:661.183.2
doi:10.5937/zasmat1804501K


Zastita Materijala 59 (4)
501 – 506 (2018)

Determination of SRG extra recovery degree from activated carbon used in water environment studies

Abstract

The purpose of this paper relates to determining the adsorption and recovery degree from activated carbon bags of Sulphorhodamine G Extra (SRG Extra) which can be used as fluorescent tracer in studies of aquatic environments. The effect of the activated carbon is that traces of the used dye are strongly fixed at the surface of the carbon grains. This attribute is used in different water systems studies with fluorescent tracer experiments. Carbon bags are used for the first time in our country in karst system study of Mali me Gropa (2002). Adsorbed tracer can be extracted from carbon bags under the analytical procedures. Based on measurements of SRG Extra fluorescence intensity in standard solutions and extracts we can calculate its adsorption and recovery degree from activated carbon bags. The obtained results prove that extreme low traces of SRG Extra, which cannot be detected directly in the water sample, can be determined in carbon extracts.

Keywords: Synchronous scan, Fluorescence Intensity (IF), Activated carbon, Artificial tracer, SRG Extra.

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ODREĐIVANJE SRG DODATNOG STEPENA OPORAVKA AKTIVNOG UGLJA KOJI SE  KORISTI U ISTRAŽIVANJU VODENE SREDINE 

Izvod

Svrha ovog rada se odnosi na određivanje stepena adsorpcije i oporavka  vreća sa aktivnim ugljem od Sulphorhodamine G Ekstra (SRG Extra), koji se može koristiti kao fluorescentni tragač u studijama o vodenoj sredini. Efekat aktiviranog uglja je da su tragovi korišćene boje snažno fiksirani na površini ugljeničnih zrna. Ovaj atribut se koristi u različitim studijama vodenih sistema sa fluorescentnim tragačkima u  eksperimentima.

Ugljene vrećice se prvi put koriste u našoj zemlji u studiji karst sistema za ”Mali me Gropa” (2002). Adsorbovani tragač se može izvući iz ugljenih vreća u analitičkim postupcima. Na osnovu merenja SRG Extra intenziteta fluorescencije u standardnim rastvorima i ekstraktima možemo izračunati njegov stepen adsorpcije i oporavka aktivnog uglja u kesama. Dobijeni rezultati dokazuju da ekstremno niski tragovi SRG Extra, koji se ne mogu direktno detektovati u uzorku vode, mogu biti određeni u ekstraktima ugljenika.

Ključne reči: sinhrono skeniranje, intenzitet fluorescencije (IF), aktivni ugalj, veštački tragač, ekstra  SRG.

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Luljeta Pinguli*, Xhaklina Cani, Ilirjan Malollari, Dhurata Premti

University of Tirana, Faculty of Natural Sciences, Department
of Industrial Chemistry, Blv “Zogu I”, Tirana, Albania

Scientific paper
ISSN 0351-9465, E-ISSN 2466-2585
UDC:663.42.001.7
doi:10.5937/zasmat1804507P

Zastita Materijala 59 (4)
507 – 513 (2018)

Advantages of using chlorine dioxide in brewing industry

Abstract

In a brewery it is very important to ensure hygienic conditions. Chlorine dioxide is a multispectral disinfectant that is more powerful, easier to use, and more environmentally friendly than chlorine. Usage of chlorine dioxide in a brewery has a lot of advantages because it can be used in different places for different purposes. Chlorine dioxide is able to penetrate, disrupt and destroy the biofilm where chlorine is completely ineffective. The main applications include, cleaning in place process (CIP) and sanitizing operations. It is noticed that chlorine dioxide is very effective especially when it is used as the final sanitizing rinse agent in CIP systems. The second application most important is to control biofilms found randomly on heat exchange surfaces, in pipes, lines, orifices pumps, conveyors, chains etc. In the form of spray solution can be used as a manual sanitizing agent for different surfaces such as for example, filler head assemblies during filling process. A very important application is at water filtration and distribution system disinfection. Chlorine dioxide is very effective when it is used for water disinfection both used for drinking and housekeeping. Ambient hygiene control especially in filling line is very important. Misting of chlorine dioxide solutions into air streams prevents the spread of mould and wild yeast. Chlorine dioxide is also an excellent odor neutralizer, helping to control mould and odor control. This process controls “off-tastes” in the final product. Chlorine dioxide solutions are also very effective for sanitizing and removing biofilms from the internal surfaces of transportation vessels. In order to have optimal results it is needed a careful study, because for each application the range of concentration and contact time is different. On the other hand it is very important to control his corrosive properties.

Keywords: chlorine dioxide, sanitizing agent, biofilm, corrosion.

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PREDNOSTI KORIŠĆENJA HLOR-DIOKSIDA U INDUSTRIJI PIVA

Izvod

U industriji piva je veoma važno osigurati higijenske uslove. Hlor-dioksid je multispektralno dezinfekciono sredstvo koje je moćnije, lakše za korišćenje i ekološki prihvatljivije od hlora. Upotreba hlor-dioksida pri proizvodnji piva ima puno prednosti jer se može koristiti na različitim mestima za različite namene. Hlor-dioksid može penetrirati, poremetiti i uništiti biofilm za koji je hlor potpuno neefikasan. Glavne aplikacije obuhvataju proces čišćenja u mestu (CIP) i saniranje postupka. Očigledno je da je hlor-dioksid veoma efikasan, posebno kada se koristi kao poslednje sredstvo za ispiranje u CIP sistemima.

Druga najvažnija primena je kontrola biofilmova pronađenih slučajno na površinama za razmenu toplote, u cevima, procesnim linijama, otvorima pumpi, transporterima, lancima itd. U obliku sprej rastvora može se koristiti kao sredstvo za ručno saniranje različitih površina, kao što su npr., sklopovi glave za punjenje tokom procesa punjenja.

Veoma važna primena je dezinfekcija linija filtracije vode i distribucije. Hlor-dioksid je vrlo efikasan kada se koristi za dezinfekciju vode, kako za piće, tako i u domaćinstvima. Posebno je važna kontrola higijene ambijenta, naročito u liniji za punjenje. Hlor-dioksid je, takođe, odličan neutralizator mirisa. Ovaj proces kontroliše “ukus” u finalnom proizvodu. Korišćenje hlor-dioksida je, takođe, vrlo efikasno za sanaciju i uklanjanje biofilmova sa unutrašnjih površina transportnih posuda. Da bi se postigli optimalni rezultati potrebna je pažljiva studija, jer je za svaku aplikaciju raspon koncentracije i vreme kontakta različit. Sa druge strane, veoma je važno kontrolisati njegove korozivne osobine.

Ključne reči: hlor-dioksid, sredstvo za saniranje, biofilm, korozija.

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Alexander G. Krivenko1, Roman A. Manzhos1, Mitar Lutovac2, Sonja Ketin3*

1Institute of Problems of Chemical Physics, Russian Academy of Sciences, Chernogolovka, Moscow Region, Russia, 2Union Nikola Tesla, Faculty of Management, Sremski Karlovci, Serbia, 3Faculty of Maritime Academic Studies, Belgrade, Serbia

Scientific paper
ISSN 0351-9465, E-ISSN 2466-2585
UDC:661.666.3/.4:093.3(n)
doi:10.5937/zasmat1804514K

Zastita Materijala 59 (4)
514 – 518 (2018)

Oxygen reduction reaction on covalently and noncovalently modified carbon nanowalls

Abstract

An effect of highly oriented carbon nanowalls modification on oxygen reduction reaction was studied by means of a rotating disk electrode. Namely nanowalls were modified with oxygen-containing functional groups. Moreover, an adsorption of borneol (a surfactant with two-dimensional structure) was considered. Two distinct waves are observed on voltammograms in aerated alkaline solutions that points out to the two-step process of oxygen reduction with the formation of H2O2 as intermediate. Both types of surface modification were found to affect substantially the absolute currents of the waves as well as their ratio. This effect was assumed to be caused by the topology peculiarities of carbon nanowalls that determine the electrochemical heterogeneity of the electrode surface. For initial nanowalls, the process of two-step reduction takes place on the edges of nanowalls. A parallel channel of oxygen reduction with the formation of water is assumed to be realized on the defects of basal planes at high overvoltage. In the case of noncovalent modification, borneol is adsorbed mainly on basal planes of nanowalls and blocks substantially parallel reduction channel. After covalent modification, oxygen reduction proceeds mainly through a two-step channel as a result of the increase in the number of oxygen-containing functional groups (the centers of two-step reduction) on the edges of nanowalls.

Keywords: carbon nanowalls, functionalization, adsorption, oxygen reduction reaction, rotating disk electrode.

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REAKCIJA REDUKCIJE KISEONIKA NA KOVALENTNO I NE-KOVALENTNO MODIFIKOVANE  NANOCEVI UGLJENIKA 

Izvod

Proučavan je efekat visoko-orijentisane modifikacije ugljeničnih nanovalls na reakciju redukcije kiseonika pomoću rotirajuće diskove elektrode. Naime, nanovalls su modifikovani sa funkcionalnim grupama koje sadrže kiseonik. Štaviše, razmotrena je adsorpcija borneola (surfaktant sa dvodimenzionalnom strukturom). Dva različita talasa se posmatraju na voltamogramima u aeracionim alkalnim rastvorima koja ukazuju na dvostepeni proces redukcije kiseonika uz formiranje H2O2 kao intermedijera. Utvrđeno je da oba tipa površinske modifikacije značajno utiču na apsolutne struje talasa, kao i njihov odnos. Pretpostavlja se da je ovaj efekat prouzrokovan topološkim karakteristikama nanošenja ugljenika koji određuju elektrohemijsku heterogenost površine elektrode. Za početne nanovalls, proces redukcije u dva koraka se odvija na ivicama nanovalls-a. Pretpostavlja se da se paralelni kanal redukcije kiseonika sa formiranjem vode realizuje na defektima bazalnih ravnina pri visokom prenaponskom naponu. U slučaju nekovalentne modifikacije, borneol se adsorbuje uglavnom na bazalnim ravninama nanovalls-a i blokira u suštini paralelni kanal redukcije. Nakon kovalentne modifikacije, smanjenje kiseonika ide uglavnom kroz dvostepeni kanal kao rezultat povećanja broja funkcionalnih grupa koje sadrže kiseonik (centri dvostepenog smanjenja) na ivicama nanovalls-a.

Ključne reči: ugljenične nanocevi, funkcionalizacija, adsorpcija, redukcija kiseonika, rotirajuća disk elektroda.

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Aldi Kuqo*, Ilirjana Boci, Sonila Vito, Sidorela Vishkulli

University of Tirana, Faculty of Natural Sciences, Department of Industrial Chemistry, Tirana, Albania

Scientific paper
ISSN 0351-9465, E-ISSN 2466-2585
UDC:620.16.199:666.973.2
doi:10.5937/zasmat1804519K


Zastita Materijala 59 (4)
519 – 523 (2018)

Mechanical properties of lightweight concrete composed with Posidonia Oceanica fibres

Abstract

This study aims to the preparation of lightweight concrete with lignocelulosic fibres from Posidonia Oceanica balls. PO balls can be found in large amounts along the Mediterranean shores. Based on previous scientific research, it has been found that they possess have very interesting properties such fire resistance, moisture resistance and thermal resistance and can serve as a raw material for the production of composites at a very low cost. In the current research it is attempted to examine flexural and compressive resistance of the PO fibres concrete. Results obtained from the tests indicate that PO fibres can be used as a substitute of aggregate producing lightweight concrete.

Keywords: Natural fibres, Sea grass, Posidonia Oceanica, Lightweight concrete.

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MEHANIČKE OSOBINE LAKOG BETONA SASTAVLJENOG OD POSIDONIA OCEANICA VLAKANA

Izvod

Ovaj rad ima za cilj dobijanje lakog betona sa lignoceluloznim vlaknima iz loptica Posidonia Oceanica. PO loptice se mogu naći u velikim količinama duž obale Mediterana. Na osnovu prethodnih naučnih istraživanja ustanovljeno je da ove materije imaju veoma interesantna svojstva poput otpornost na vatru, otpornost na vlagu i toplotne otpornosti i mogu poslužiti kao sirovina za proizvodnju kompozita po veoma niskoj ceni. U tekućem istraživanju pokušava se ispitati otpornost na pritisak i savojna čvrstoća PO vlakna betona. Rezultati dobijeni testovima pokazuju da se PO vlakna mogu koristiti kao zamena za agregat kojim se dobija laki beton.

Ključne reči: prirodna vlakna, morska trava, Posidonia Oceanica, lagan beton.

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Valbona Hoxha1, Kozeta Vaso2, Albana Jano1, Enkela Poro1

1Polytechnic University of Tirana, Albania, Department of Chemistry, Faculty of Mathematical Engineering and Physical Engineering, Tirana, Albania, 2University of Tirana, Albania, Department of Chemistry , Faculty of Natural Sciences, Tirana, Albana

Scientific paper
ISSN 0351-9465, E-ISSN 2466-2585
UDC:504.45:628.113.16.08(496.5)
doi:10.5937/zasmat1804524H


Zastita Materijala 59 (4)
524 – 528 (2018)

Study of physico- chemical parameters of surface waters in the Lana River, Albania

Abstract

The water quality in the Lana River has been and currently is under the influence of a number of factors. However, we emphasize that the main impact comes from anthropogenic activities, exactly pollutation from discharges of urban wastewater.

This article presents the results of the study of the physical and chemical parameters of surface waters in the Lana River. The study report discusses about the analysis of river water quality.

The water samples for this study, taken were carried out on four expeditions in the months of  May, June, July, September 2016, at five monitoring stations at: the upper part of the river flow (Lanabregas) , the middle stream of the river (New Maternity and Palace with Arrow ), and downstream of the river, (Yrshek – ex Customs and Domje).

Collection, preservation and conservation of samples was carried out in accordance with the recommended standard methods. Parameters:  temperature, electrical conductivity, pH, DO, and % DO were analyzed directly on the site using WTW Multimeter 3420 Set G apparatus. Other chemical parameters were analyzed in the Chemistry Laboratory of the Faculty of Mathematical Engineering and Physical Engineering based on recommended standard methods.

The obtained results showed high values of the quality parameters studied, and compared to international standards such as NIVA classification, UNECE, and EU standards, the Lane River waters are of very bad environmental quality.

At the conclusion of this study, we recommend, establishing a continuous monitoring system of water quality studied and strengthening the controls of urban waste-free discharge in the river.

Keywords: water pollution, Lana River, physico-chemical analysis.

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FIZIČKO-HEMIJSKI PARAMETRI POVRŠINSKIH VODA REKE LANA, ALBANIJA

Kvalitet vode u reci Lani je pod uticajem više faktora. Međutim, glavni uticaj na kvalitet vode dolazi od antropogenih aktivnosti, tačnije od zagađenja usled ispuštanja urbanih otpadnih voda.
U ovom članku prikazani su rezultati istraživanja fizičkih i hemijskih parametara površinskih voda u reci Lani. Izveštaj u radu govori o analizi kvaliteta rečne vode.

Uzorci vode za ovu studiju izvedeni su u toku četiri meseca: maj, juni, juli i septembar 2016. godine, na pet stanica za monitoring: gornji deo rečnog toka (Lanabregas), srednji tok reke (New Maternity and Palace with Arrow), i nizvodno od reke, (Yrshek – ex Customs and Domje). Sakupljanje, čuvanje i konzerviranje uzoraka vršeno je u skladu sa preporučenim standardnim metodama. Parametri: temperatura, električna provodljivost, pH, DO i %DO su analizirani direktno na lokaciji pomoću uređaja VTV Multimeter 3420 Set G. Drugi hemijski parametri analizirani su u hemijskoj laboratoriji Fakulteta za matematičko inženjerstvo i fizičko inženjerstvo, Tirana, na osnovu preporučenih standardnih metoda.

Dobijeni rezultati pokazuju visoke vrednosti ispitivanih parametara kvaliteta vode i upoređeni sa međunarodnim standardima, kao što su NIVA klasifikacija, UNECE i EU standardi, vode reke Lane su veoma lošeg kvaliteta. Na osnovu ovih ispitivanja preporučuje se uspostavljanje sistema kontinuiranog monitoringa kvaliteta vode i jača kontrola izlivanja urbanih otpadaka u reci.

Ključne reči: zagađenje voda, reka Lana, fizičko-hemijska analiza.

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Sidorela Vishkulli*, Nereida Dalanaj, Ilirjana Boci, Sonila Vito, Aldi Kuqo

University of Tirana, Department of Industrial Chemistry, Faculty of Natural Sciences, Tirana, Albania

Scientific paper
ISSN 0351-9465, E-ISSN 2466-2585
UDC: 667.622.2:669.227-492.2(n)
doi:10.5937/zasmat1804529V

Zastita Materijala 59 (4)
529 – 533 (2018)

Investigation of the efficiency of silver nanoparticles suspension in paints of indoor environment

Abstract

Over the last few decades, nanoparticles of metals have been attracted attention for the wide range of applications in various fields of industry, especially Ag nanoparticles which have been used for their biocidal properties. On the other hand painting is practiced since in ancient times for decoration, but the paint surfaces undergo damage due to natural weathering and the growth and activity of living organisms. Various types of organisms are involved in paint spoilage, such as bacteria, algae and fungi. To prevent paints from biodeterioriation are used biocide substances, which with time have caused environmental and health problems. In this experimental work we aimed to investigate the antifungal efficiency of silver nanoparticles compared to a trade biocide substance sold in our market for paints of indoor environment. A series of microbiological tests were carried out. The results obtained showed that Ag nanoparticles are effective in inhibition of fungal growth.

Keywords: paints, mycological resistance, Ag nanoparticles.

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ISTRAŽIVANJE EFIKASNOSTI SUSPENZIJE NANOČESTICA SREBRA NA BOJAMA U ZATVORENOM PROSTORU

Tokom poslednjih nekoliko decenija, nanočestice metala su privukle pažnju za široki spektar primena u različitim oblastima industrije, posebno Ag nanočestice, koje su korišćene zbog njihovih biocidnih osobina. Sa druge strane, slikarstvo se koristi još od drevnih vremena za dekoraciju, ali se površini boja nanosi šteta zbog prirodnog vremenskog uticaja, kao i rasta i aktivnosti živih organizama. Različite vrste organizama uključene su u kvarenje boje, kao što su bakterije, alge i gljivice. Da bi se sprečila biodegradacija boje, korišćene su biocidne supstance, koje su vremenom izazvale probleme životne sredine i zdravlja. U ovom eksperimentalnom radu želelo se da istraži antifungalna efikasnost srebrovih nanočestica u poređenju sa trgovinskom biocidnom supstancom koja se na tržištu prodaje za zaštitu boja u unutrašnjem okruženju. Izvršena je serija mikrobioloških testova. Dobijeni rezultati pokazuju da su Ag nanočestice efikasnije u inhibiciji rasta gljivica.

Ključne reči: boje, mikološka otpornost, Ag nanočestice.

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Jonida Canaj1*, Kozeta Vaso2

1Institute of Public Health, Department of Environment and Public Health,Tirana, Albania, 2University of Tirana, Department of Chemistry, Faculty of Natural Sciences UT,Tirana, Albania

Short Communication
ISSN 0351-9465, E-ISSN 2466-2585
UDC:504.45:628.161.2.033
doi:10.5937/zasmat1804534C


Zastita Materijala 59 (4)
534 – 538 (2018)

PAHs in drinking water and contamination source of it

Abstract

Polycyclic aromatic hydrocarbons (PAHs) are ubiquitous in the environment and are part of numerous organic contaminants that are persistent in the environment. This study was undertaken to assess the identification and concentration of 15 PAHs in drinking water in different geographic regions of Albania. Another purpose is to explain the exposure of them to human health. There are thousands of PAH compounds in the environment but in practice PAH analysis is restricted to a few compounds as: Naphthalene, Acenaphthylene, Acenaphthene, Fluorene, Phenanthrene, Anthracene, Fluoranthene, etc listed by US EPA as potentially toxic. This article describes a reproducible method according to EN ISO 17993:2003 for sample preparation and HPLC analysis of PAHs in water, fluorescence detection mode after liquid-liquid extraction for the determination of 15 selected PAH in drinking and ground water. All the results of the water samples are negative, it is not possible to detect these compounds.

Keywords: contamination, polycyclic aromatic hydrocarbons, drinking water, human health.

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PAH U PIJAĆOJ VODI I IZVORI KONTAMINACIJE

Izvod

Policiklični aromatični ugljovodonici (PAHs) su prisutni u okruženju i deo su brojnih organskih zagađivača koji su uporni u životnoj sredini. Ova studija je preduzeta da bi se procenila identifikacija i koncentracija 15 PAH u pitkoj vodi u različitim geografskim regionima Albanije. Druga svrha studije je da se objasniti njihov uticaj na ljudsko zdravlje. Postoje hiljade PAH jedinjenja u okruženju, ali u praksi PAH analiza je ograničena na nekoliko jedinjenja: Naftalen, Acenaphthilene, Acenaphene, Fluoren, Fenantren, Antracen, Fluoranten itd., koji su navedeni u US EPA kao potencijalno toksični. Ovaj članak opisuje ponovljivu metodu prema EN ISO 17993: 2003 za pripremu uzorka i HPLC analizu PAH u vodi, detekciju fluorescencije nakon ekstrakcije tečnosti i tečnosti za određivanje 15 odabranih PAH u pitkoj i podzemnoj vodi. Svi rezultati uzoraka vode su negativni, nije moguće otkriti ova jedinjenja.

Ključne reči: kontaminacija, policiklični aromatični ugljovodonici, voda za piće, zdravlje ljudi.

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Adelaida Andoni1*, Eda Delilaj1, Fatos Ylli2, Krenaida Taraj1, Arjan Korpa1, Kledi Xhaxhiu1, Armand Çomo1

1University of Tirana, Faculty of Natural Sciences, Department of Chemistry, Blv. “Zog I”, Tirana, Albania, 2University of Tirana, Institute of Applies Nuclear Physics, Tirana, Albania

Short Communication
ISSN 0351-9465, E-ISSN 2466-2585
UDC:543.51:662.613.11.13
doi:10.5937/zasmat1804539A


Zastita Materijala 59 (4)
539 – 542 (2018)

FTIR spectroscopic investigation of alkali-activated fly ash: Atest study

Abstract

Fly ash is byproduct of thermal power plants. Millions tons of fly ash is produced globally. Fly ash is disposed partly in landfills but it could also be released into the atmosphere in the past. Fly ash is composed of silica, alumina, iron oxide, magnesia and activated carbon. Due to large surface area, fly ash is very suitable for catalysis application. It is well known and well reported that fly ash can be converted into efficient adsorptive material such as zeolites. In the present work, the transformation of fly ash into zeolite was carried out by alkali activation process of alumino-silicates material. The alkali solution releases silicon and aluminum ion into solution, which form afterwards Si–OH and Al–OH groups. FTIR spectroscopy was applied to characterize fly ash chemical activation, in order to conduct a study making intensive use of infrared spectroscopy and further to provide information on chemical bond vibrations in the molecular units of fly ash. The FTIR spectrum of solid base fly ash (SBFA) after chemical activation shows a significant increase in peak intensity of the band for –OH group.

Keywords: fly ash, chemical activation, catalyst, FTIR spectroscopy.

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FTIR SPEKTROSKOPSKO ISTRAŽIVANJE ALKALNO AKTIVIRANOG PEPELA

Leteći pepeo je nusproizvod termoelektrana. Milioni tona letećeg pepela se proizvodi širom sveta. Leteći pepeo se delimično uklanja u deponije, ali bi se mogao puštati u atmosferu. Leteći pepeo čine silicijum, glinice, gvožđe oksid, magnezijum i aktivni ugalj. Zahvaljujući velikoj površini, leteći pepeo je veoma pogodan za primenu kao katalizator. Poznato je i prijavljeno je da se leteći pepeo može pretvoriti u efikasan adsorpcioni materijal, kao što su zeoliti. U sadašnjem radu, transformacija letećeg pepela u zeolit izvršena je procesom alkalne aktivacije materijala aluminijum-silikata. Alkalni rastvor daje silicijum i aluminijum jon u rastvoru, koji formiraju posle Si-OH i Al-OH grupe. FTIR spektroskopija primenjena je za karakterizaciju hemijske aktivacije letećeg pepela, kako bi se sprovela studija koja intenzivno koristi infracrvenu spektroskopiju i dalje pruža informacije o vibracijama hemijskih veza u molekularnim jedinicama pepela. FTIR spektar elektrofilterskog pepela (SBFA) nakon hemijske aktivacije pokazuje značajno povećanje intenziteta vršnog opsega za -OH grupu.

Ključne reči: leteći pepeo, hemijska aktivacija, katalizator, FTIR spektroskopija.

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