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Zaštita materijala 1. 2012


Review paper [PDF]

Formation of carcinogenic substances during heating of foods

The formation of some selected carcinogens during cooking is associated with some certain types of foods. The heterocyclic amines are mainly found in meat and fish that are cooked at temperatures above 150°. Acrylamide is formed in foods containing asparagine and reducing sugars which are present in potatoes, cereals and similar products. The formation of acrylamide needs high temperatures similar to the HCAs which are occurring during baking, frying, and roasting. In contrast to the other two types of substances 5-hydroxymethyl-2-furfural is formed at lower temperatures and even during storage from carbohydrates in presence of amino acids or from fructose by direct dehydration. Since all these compounds are by-products of the aroma forming reactions it is difficult to find ways to reduce the content in foods without changing the characteristics of the food products. A proper selection of the raw materials and well controlled cooking/processing procedures in combination with a reduced uptake of some highly contaminated foods can give us a possibility to reduce the exposure.

Key words: carcinogenic substances, contaminated foods, heating


Formation of carcinogenic substances during heating of foods

The formation of some selected carcinogens during cooking is associated with some certain types of foods. The heterocyclic amines are mainly found in meat and fish that are cooked at temperatures above 150°. Acrylamide is formed in foods containing asparagine and reducing sugars which are present in potatoes, cereals and similar products. The formation of acrylamide needs high temperatures similar to the HCAs which are occurring during baking, frying, and roasting. In contrast to the other two types of substances 5-hydroxymethyl-2-furfural is formed at lower temperatures and even during storage from carbohydrates in presence of amino acids or from fructose by direct dehydration. Since all these compounds are by-products of the aroma forming reactions it is difficult to find ways to reduce the content in foods without changing the characteristics of the food products. A proper selection of the raw materials and well controlled cooking/processing procedures in combination with a reduced uptake of some highly contaminated foods can give us a possibility to reduce the exposure.

Key words: carcinogenic substances, contaminated foods, heating




Scientific paper [PDF]

Sodium tungstate – Zn2+  as corrosion inhibitor for carbon steel

The inhibition efficiency of a sodium bisulphite (SBS) in combination with a bivalent cation like Zn2+ in controlling corrosion of carbon steel was investigated by weight – loss method. A formulation consisting of Zn2+, sodium tungstate, ST, and SBS can be used as a potent inhibitor to prevent the corrosion attack to carbon steel in neutral aqueous media. The ternary system ST (20ppm), Zn2+ (50ppm) and SBS (10ppm) is effective and has 95% I.E. The protective film consists of Zn(OH)2 and complexes of Fe2+ / Fe3+ and Zn2+ with SBS and ST. These complexes formation are confirmed by UV-Visible, FTIR and atomic force microscopic (AFM) spectra. The surface morphology of the protective film on the metal surface is also characterized by AFM.

Key words:- Corrosion inhibition, carbon steel, sodium tungstate, sodium bisulphite, Zn2+, UV-visible and FTIR spectra, atomic force microscopy, mechanism.


Натријум волфрамат–Zn2+ као корозиони инхибитор за угљенични челик

Ефикасност инхибиције натријум-бисулфитом (SBS) у комбинацији са двовалентним катјоном као што је Zn2+ у контроли корозије угљеничног челика истражена је методом губитка масе. Формулација која се састоји од Zn2+, натријум-волфрамата, ST, и SBS може да се користи као снажан инхибитор у спречавању корозије угљеничног челика у неутралној воденој средини. Тернарни систем ST (20 ppm), Zn2+ (50 ppm) и SBS (10 ppm) је ефикасан и има инхибирајућу ефикасност од 95%. Заштитни филм се састоји од Zn(OH)2 и комплекса Fe2+/Fe 3+ и Zn2+ са SBS и ST. Формирање ових комплекса је потврђено UV-Visible, FTIR и AFM спектрима. Морфо­логија заштитног филма на металној површини је окарактерисана применом микроскопије засноване на међуатомским силама (AFM).

Кључне речи: Инхибиција корозије, угљенични челик, натријум-волфрамат, натријум-бисулфит, Zn2+, UV-Visible и FTIR спектри, микроскопија заснована на међуатомским силама, механизам.




Scientific paper [PDF]
UDC :620.197.3 :669.715

Inhibition of Al-Mg alloy in hydrochloric acid using schiff bases as corrosion inhibitors

The effect of some new synthesized Schiff bases namely o-Chloroaniline-N-(p-methoxy benzylidene) and p-Chloroaniline-N-(p-methoxy benzylidene) on the corrosion of Al-Mg alloy in 2 M HCl was investigated. The investigation involved weight loss, galvanostatic polarization and EIS measurements. The inhibition efficiency increased with increase in inhibitor concentration but decreased with increase in temperature. Schiff bases are found to adsorb on the metal surface according to the Langmuir isotherm. Thermodynamic parameters and activation energy were calculated to elaborate the mechanism of inhibition. The results of polarization method show that these Schiff bases act as mixed type, but the cathode is more preferentially polarized.

Key words : Aluminium, EIS, Polarization, Weight loss, Acid inhibition



Утицај неких ново синтетизованих Шифових база типа о-хлороанилин-N-(p-метокси бензилиден) и p -хлороанилин-N-(p-метокси бензилиден) на корозију Al-Mg легуре у 2 M HCl је био истражен. Истраживање је обухватило одређивање губитка тежине, галваностатска поларизациона мерења и мерење методом електрохемијске импедансне спектроскопије. Ефикасност инхибиције се повећавала са повећањем концентрације инхибитора али се смањивала са повећањем температуре. Нађено је да су се Шифове базе адсорбовале на металној површини према Ленгмировој изотерми. Термодинамички параметри и активациона енергија су били срачунати да елаборирају механизам инхибиције. Резултати поларизационих мерења показују да ове Шифове базе делују као мешовити тип, али катода је првенствено поларизована.

Кључне речи: алуминијум, електрохемијска импедансна спектроскопија, поларизација, губитак тежине, инхибиција



Scientific paper [PDF]

Study of inhibition properties of some thiazole derivatives against copper corrosion

The inhibitor efficiency of some thiazole derivatives against copper corrosion in acidic sulfate solution were investigated using polarization and electrochemical impedance spectroscopy (EIS) methods.  Protection efficiency of  four organic molecules: 5-benzylidene-2,4-dioxotetrahydro-1,3-thiazole (5-BDT), 5-(4¢-isopropylbenzylidene)-2,4-dioxotetrahydro-1,3-thiazole (5-IPBDT), 5-(3¢-thenylidene)-2,4-dioxotetrahydro-1,3-thiazole (5-TDT) and 5-(3¢,4¢-dimetoxybenzylidene)-2,4-dioxotetrahydro-1,3-thiazole (5-MBDT) were investigated on copper electrode in 0.1moldm–3 Na2SO4 solution at pH=2.95. Polarization measurements indicates that all investigated thiazole derivatives could reduces the cathodic reaction rate on copper electrode surface in 0.1 mol dm–3 acidic Na2SO4 solution. In investigation range concentration 0.01mmoldm-3 has the best inhibitor efficiency in case of all investigated thiazole. The best protection is obtained in presence of 5-IPBDT derivatives. EIS results showed that investigated thiazole derivatives formed a film on copper surface which was able to protect copper against corrosion in acidic media. 5-IPBDT derivative only formed closely packed inhibitor film, which is able to protect copper surface during the time.

Key words: inhibitors, corrosion, copper, properties


Ispitivanje inhibitorskih svojstva derivata tiazola na koroziju bakra

Ispitivana je inhibitorska efikasnost odabranih derivata tiazola u odnosu na koroziju bakra u kiseloj sredini snimanjem polarizacionih krivi i impedansnim merenjima. Određivana je zaštitna sposobnost sledećih organskim molekula: 5-benziliden-2,4-dioksotetrahidro-1,3-tiazol (5-BDT), 5-(4¢-izopropil­benziliden)-2,4-dioksotetrahidro-1,3-tiazol (5-IPBDT), 5-(3¢-teniliden)-2,4-dioksotetrahidro-1,3-tiazol (5-TDT) i 5-(3¢,4¢-dimetoksibenziliden)-2,4-dioksotetrahidro-1,3-tiazol (5-MBDT) u 0,1mol/dm–3  rast­voru Na2SO4 pri pH=2,95. Polarizaciona merenja ukazuju da svi ispitivani derivati tiazola smanjuju brzinu redukcije kiseonika, delujući kao katodni inhibitori korozije bakra kiselom u 0,1mol dm–3 rastvoru Na2SO4. U ispitivanom opsegu, koncentracija od 0,01 mmoldm-3 ima najveću inhibitorsku efikasnost kod svih ispitivanih derivata. Najbolja zaštita uočena je kod 5-IPBDT derivata. Merenja impedanse pokazuju da ispitivana jedinjenja formiraju film na površini bakarne elektrode koji je sposoban da štiti bakar od korozije u kiseloj sredini. 5-IPBDT derivat jedino formira dovoljno kompaktan film, koji može da štiti bakar od korozije u dužem vremenskom periodu.

Ključne reči: inhibitori, korozija, bakar, svojstva


Originalni naučni rad [PDF]

Istraživanje korozionih i elektrohemijskih karakteristika nemodifikovanih AlZnSnGaIn legura u rastvorima NaCl

U ovom radu su prikazani rezultati nemodifikovanih AlZnSnGaIn legura, dobijenih u laboratoriji za Livarstvo MTF-a Podgorica. Pomenuti uzorci su ispitivani na savremenoj PAR opremi u realnim rastvorima NaCl, bez prethodnog uvođenja azota ili drugih gasova. Savremenim metodama određene su vrijednosti: Rp, jcorr, ecorr, e(j=0), kao i katodne i anodne polarizacione krive za nemodifikovane AlZnSnGaIn legure. Istraživanja su rađena u rastvorima NaCl koncentracija od 5,1*10-4 do 1,02 mol/dm3.

Ključne reči: korozija, nemodifikovane legure, polarizacione krive


Investigation of corrosion and electrochemical characteristics of AlZnSnGaIn unmodified alloys in NaCl solutions

This paper presents the results of unmodified AlZnSnGaIn alloys, obtained in the Laboratory for casting in Faculty of Metallurgy and Technology – Podgorica. The aforementioned samples were analyzed at the modem PAR equipment in real solutions of NaCl, without the introduction of other gases. Modern methods were determined: polarization resistance, corrosion current density, corrosion potential, e(j=0), and cathodic and anodic polarization curves for unmodified AlZnSnGaIn alloy. Investigations were carried out in solutions of sodium chloride concentration of 5,1·10-4 to 1,02 mol/dm3.

Key words: corrosion, unmodified alloys, polarization curves



Originalni naučni rad [PDF]

Fotoelektrohemiska ispitivanja tankih filmova formiranih na Nb elektrodama u alakalnim rastvorima

Fotoelektrohemijska istraživanja tankih pasivnih i anodnih filmova izvodjena su na Nb elektrodi u rastvoru 2 M KOH. Pokazano je da formirani pasivni filmovi imaju poluprovodničke osobine čija širina zabranjene zone iznosi 3.26 eV. Sa povećanjem napona do 10 V povećava se debljina anodnih filmova a opada širina zabranjene zone. U području napona od 10 V do 30 V debljina anodnih filmova i dalje raste dok širina zabranjene zone poprima konstantnu vrednost od 3.06 eV.

Ključne reči: fotosinteza, pasivni i anodni  filmovi, zabranjene zone, poluprovodnici



Photo electrochemical investigations of thin passive and anodic films on Nb electrodes in 2 M KOH have been performed. It was shown that the formed passive films have semi-conducting properties with band gap energy of 3.26 eV. By increasing the film thickness of anodic films decrease the value of band gap energy and for films formed from 10 V to 30 V this energy has a constant value of 3.06 eV.

Key words: Photosynthesis, the anodic passive films, band gap, semiconductors



Originalni naučni rad [PDF]

Uporedna svojstva uretan-alkidnih i vodorazredivih premaza za površinsku obradu drveta u eksterijeru

Zaštita drveta u eksterijeru, kao što su okviri prozora i vrata, može se vršiti primenom različitih sistema premaza. Najviše u upotrebi su konvencionalni isparavajući premazi – na bazi rastvarača (alkidni, modifikovani alkidi itd.). Poslednjih godina, zbog normativno restriktivne emisije organskih rastvarača, trend razvoja premaza dovodi do smanjenja isparljivih organskih komponenti. Smanjuje se prisustvo organskih rastvarača ili zamenjuju ekološki bezbednijim rastvaračima, kao što su voda ili alifatični rastvarači. Premazi na bazi vode su u stalnom razvoju. Pored smanjene emisije rastvarača premazi na bazi vode imaju i mnoge druge prednosti, kao i neke nedostatke, u poređenju sa klasičnim premazima sa rastvaračima. U ovom radu se analiziraju i upoređuju karakteristike vodorazredivog premaza na bazi akrilne disperzije sa modofikovanim uretan-alkidnim premazom.

Ključne reči: drvo, eksterijer, površinska zaštita, uretan-alkidni premazi, vodorazredivi premazi, UV zračenje, adhezija, upijanje vode, propustljivost vodene pare



The protection of wood elements in the exterior use, such as window frames and doors, can be performed with various type of coatings. The most diffused in use are conventional coatings – solvent-based (alkyd, modified alkyds etc.). Last years, because of the restrictive normative regarding the solvent emission, the trend of coatings development leads to the reduction of volatile organic components. Organic solvents are reduced or substituted by environmentally safer solvents such as water or aliphatic solvents. Water based coatings are in constant development. Besides the reduced solvent emission, water based coatings have many other advantages, as well as some disadvantages in comparison with classic, solvent type of coatings. In this paper, the characteristics of water based (acrylic dispersions) and urethan modified alkyd coatings are analysed and compared.

Key words: wood, exterior, surface protection, urethane-alkyd coatings, water based coatings, UV-radiation, adhesion, water penetration , water vapour permeability



Originalni naučni rad [PDF]

Korozija i zaštita rashladnog sistema

Korozija u rashladnim sistemima je spontan,složen hemijski proces na koji utiču fizički i hemijski faktori. Javlja se u nekoliko oblika, a najpodmuklija je piting korozija. Mada različite materije se mogu koristiti kao inhibitori korozije, najviše efekta u zaštitu od korozije rashladnih sistemima imaju fosfonati, posebno sinergistički blendirani fosfonati i polimeri „all organic“. U Termoelektrani Ugljevik se fosfonati koriste nekoliko godina i u ovom radu će se komentarisati iskustva njihove primjene.

Ključne riječi: korozija , inhibitori, rashladni system


Corrosion and protection of cooling system

Corrosion in cooling systems is a spontaneous chemical complex process influenced by physical and chemical factors. It occurs in several forms, and most insidious is pitting corrosion. Although different materials can be used as corrosion inhibitors, the most effect in the corrosion protection of cooling systems are phosphonates, especially synergistic coupled phosphonates and polymers “all organic”.  The power plant Ugljevik phosphonates used for several years and this paper will comment on the experience of their application.

Key words: corrosion, inhibitors, cooling system



Scientific paper [PDF]

Arsenic removal through coagulation and flocculation from contaminated water in Macedonia

Arsenic removal from contaminated water from Kozuf mountain region in R. Macedonia was examined through application of processes of coagulation and flocculation with ferric ions in this work. The experimental results have shown that arsenic-borne coagulates produced by coagulation with ferric ions were filterable, so filtration (filter paper as filter medium) was needed to remove the coagulates from water. The coagulation followed by conventional filtration achieved a very high arsenic removal rate (over 90%) from contaminated arsenic water (0.4 mg/l arsenic concentration), producing cleaned water with the residual arsenic concentration of 0.02 mg/l. In the process of arsenic removal, a zero residual arsenic concentration was achieved through appropriate adjustment of pH value. The results of the research have established the relations between the added flocculants, the contact time, and the pH change and it has been found that in certain cases efficiency for arsenic removal of 100% can be achieved.

Key words: coagulant, flocculent, arsenic, contact time, pH



Uklanjanje arsena iz zagadjene vode iz planinskog regiona Kozuf u R. Makedoniji je ispitan u ovom radu primenom procesa koagulacije i flokulacija sa feri jonima. Eksperimentalni rezultati su pokazali da se arsen zgrušava pri koagulacije sa feri jonima, tako da je potrebno izvršiti filtraciju vode i očistiti je od koagulanata. zgrušava. Konvencionalna filtracijom koagulanata ostvario se veoma visok stepen uklanjanja arsena (preko 90%) od kontaminiranog arsena u voda (0,4 mg / l, koncentracija arsena), i proizvedena je očišćena voda sa rezidualnom koncentracijom arsena od 0,02 mg / l. U daljem  procesu uklanjanja arsena, nula rezidualna koncentracija arsena je ostvaren kroz odgovarajuće podešavanje pH vrednosti vode. Rezultati istraživanja su uspostavili odnos između dodatka flokulanta i vreme kontakta, kao i promene pH, pri čemu je uočeno da u nekim slučajevima može se postići efikasnost za uklanjanje arsena od 100%.

Ključne reči: koagulanti, flokulanti, arsen, kontaktno vreme, pH




Scientific paper [PDF]

The possibility of bioactive coatings obtaining by electrophoretic deposition of HAp on the steel implants


Surgical metallic implants are usually made of stainless steel, titanium- and cobalt/chromium- based alloys which have superior structural and mechanical properties, and are corrosion resistant. Nevertheless, they are susceptible to local corrosion in the human body, releasing metal ions into the nearby body tissue and fluids. Keeping the advantage of their mechanical properties, their biocompatibility can be achieved through deposition the bioinert or even bioactive coating onto their surface. Hydroxyapatite is known by its bioactive behavior, originating from its chemical identity with human bones. The electrophoretic deposition is rather old technique used here with a novel nanostructured hydroxyapatite powder to obtain uniform and dense hydroxyapatite coatings, to overcome the restrictions of previously used high temperature coating techniques and to overcome the complex geometry metallic substrate problems. The coating of nanosized hydroxyapatite was electrophoretically deposited on blasted surface of stainless steel 316LVM samples at constant voltage, for different deposition times and subsequently sintered in argon atmosphere at 1000 oC. The HAp powder thermal stability was initially assessed using DTA-TG analyses over the temperature range of 23oC-1000oC. The microstructure characterization of the coating was accomplished using SEM, and phase composition was determined by XRD.

Key words: hydroxyapatite, 316LVM stainless steel, EPD, coatings


Mogućnost dobijanja bioaktivnih prevlaka elektroforetskim deponovanjem hidroksiapatita na čelične implantate

Metalni implantati za ortopedsku hirurgiju izrađuju se najčešće od nerđajućeg čelika, legura na bazi titana, kobalta ili hroma, koje imaju odlične konstrukcione i mehaničke osobine i otporne su na koroziju. Ipak, ovakvi implantati poldožni su lokalnoj koroziji u ljudskom telu jer je zapaženo prisustvo njihovih metalnih jona u okolnim tkivima i telesnim tečnostima. Da bi se iskoristila prednost njihovih mehaničkih karakteristika, a postigla biokompatibilnost, moguće je na njihovu površinu naneti bioinertnu ili čak bioaktivnu prevlaku. Hidroksiapatit je poznat po svom bioaktivnom ponašanju, koje duguje hemijskoj istovetnosti sa ljudskim kostima. Elektroforetska deopzicija je relativno stara tehnika, koja je ovde primenjena uz upotrebu novog materijala – nanostrukturnog hidroksiapatita, kako bi se dobile ravnomerne i kompaktne hidroksi­apatitne prevlake i tako prevazišla ograničenja prethodno korišćenih visokotemperaturnih tehnika nanošenja prevlaka i problemi sa složenim oblikom metalnog supstrata. Prevlake nanostrukturnog hidroksiapatita eletroforetski su deponovane na peskiranu površinu uzoraka od nerđajućeg čelika 316LVM, pri konstantnom naponu, za različito vreme deponovanja, a zatim su sinte­rovane u atmosferi argona na 1000oC. Toplotna stabilnost HAp praha prvo je ocenjena DTA/TG analizom u temperaturnom intervalu 23oC-1000oC. Za mikrostrukturnu karakterizaciju prevlake korišćen je SEM, a za određivanje faznog sastava XRD analiza.

Ključne reči: hidroksiapatit, nerđajući čelik, EPD, prevlake




Stručni rad [PDF]

Uticaj upotrebe komprimovanog vazduha pri izvođenju bunara na rezultate fizičko-hemijskih analiza vode

Za potrebe bušenja ili kvalitetne razrade i ispiranja pijezometara i bunara, često se koristi kompri­movani vazduh. Ovim radom se ukazuje na to, da se rastvoreni kiseonik, ubačen u podzemne vode, može zadržati na velikom prostoru i dugo vremena nakon toga. To objektivno može uticati na rezultate ispitivanja fizičko-hemijskog sastava uzoraka podzemne vode, uzetih tokom prvog testiranja bunara. U radu su prezentovani rezultati ispitivanja ovog uticaja, u akviferu neogene starosti u Stanarima kod Doboja i u aluvijalnoj izdani u Kozluku kod Zvornika, Republika Srpska, korelacijom rezultata ispitivanja odmah nakon izvedbe bunara i kasnije u toku njegovog korišćenja. Kako bi se u budućnosti eliminisao ovaj problem, u radu su date preporuke za promjenu uobičajene procedure hidrogeoloških istraživanja, da se sagleda efekat aeracije vode u akviferu, tokom razrade bunara.

Ključne riječi: podzemne vode, gvožđe, mangan, amonijak, razrada bunara



The compressed air is often used for purpose of drilling or quality developing and flushing the piesometers and water wells.  This paper suggests, that the dissolved oxygen, which is injected in groundwater, can retain in a large area for a long time after the performing and cleaning of the piezometers and water wells, which objectively, might have an affect on the the testing results of physical and chemical composition of groundwater samples when we test water wells in the first time. The paper presents results of testing that influence, in the Neogene aquifer in the Stanari settlement, near of city of Doboj, and in the alluvial aquifer in the Kozluk village near city of Zvornik, by correlation of test results immediately after the performing of water wells and later, during their usage. In order to eliminate this problem in the future, this paper offers proposals, cchange of the usual procedure of hydrogeological research. It will bi possible to examine the effect of aeration of groundwater in the aquifer, during the performing of the wells.

Key words: groundwater, iron, manganese, ammonia, development of water wells



Strucni rad [PDF]
UDC :620.197.5:621.355.002.58

Regulacija rada i nadgledanje stanica za katodnu zaštitu

Efikasan način zaštite od korozije metalnih konstrukcija, opreme i uređaja koje se instaliraju u zemlji ili vodi je primena katodne zaštite. Katodna zaštita se izvodi dovođenjem odgovarajućeg negativnog potencijala na štićenu konstrukciju, u odnosu na tlo. Katodnom polarizacijom metalne konstrukcije u elektrolitičkoj sredini smanjuje se ili potpuno zaustavlja proces korozije. Izvori jednosmerne struje su instalirani u ormarima – stanicama katodne zaštite. Predmet katodne zaštite su najčešće ukopani rezervoari, vodovodi, gasovodi, naftovodi, kablovi, uzemljivači i sl., koji se prostiru na velikim površinama, tako da su i stanice katodne zaštite dosta razuđene. Problem nadzora i upravljama stanicama katodne zaštite rešava se najčešće primenom digitalnih radio uređaja ili GPRS/GSM komunikacijom. Na ovaj način stanice su povezane sa dispečerskim centrom u kome se vrši kontinualno praćenje parametara katodne zaštite i optimizacija režima rada samih stanica.

Ključne reči: katodna zaštita, izvor jednosmerne struje, prenos podataka, radio, GPRS/GSM



An effective way to of protection against corrosion of metal structures, equipment and devices that are installed in the ground or water is the application of cathodic protection. Cathodic protection is performed by bringing an appropriate negative potential in the construction of manned, to the ground. Cathodic polarization of metal constructions in the electrolytic environment reduces or completely stops the corrosion process. DC sources are installed in racks – cathodic protection stations. The subject of cathodic protection is usually buried reservoirs, water mains, gas lines, oil pipelines, cables, grounding and the like., which are spread over large areas, so that both the cathodic protection station quite jagged. The problem of monitoring and control the cathodic protection stations is usually solved using digital radio or GPRS/GSM communication. In this way cells are connected to the dispatch center where it is continuously monitoring the parameters of cathodic protection and optimization mode stations themselves.

Key words: cathodic protection, DC source, data transmission, radio, GPRS/GSM