J. RADOŠEVIĆ1), J. MALINA2), N. DOLIĆ2), P. LJUMOVIĆ1), S. SLAVICA – MATEŠIĆ3)
Scientific paper UDC:620.197.3
Susceptibility to corrosion of welded AlMgSi alloy EN AW 6060
In this paper electrochemical studies on welding joints of commercial extruded Al-alloy EN AW 6060 have been performed in order to evaluate corrosion behavior in solution of 3.5 mass.% NaCl. Potentiodynamic techniques like Tafel polarization and cyclic anodic polarization were employed in order to monitor the general corrosion resistance and pitting susceptibility. Results have shown that weld zone has cathodic character compared to the base alloy, so that passive corrosion current is higher, while pitting potential Epit and repassivation potential Erp are lower for specimens made from welded AlMgSi coupons. Key words: Corrosion of welded AlMgSi alloy EN AW-6060; Chloride medium. More >>>
Sklonost koroziji zavarene AlMgSi legure EN AW 6060
U ovom članku provedena su elektrokemijska ispitivanja na zavarenim spojevima komercijalne, ekstrudirane Al-legure EN AW-6060 u cilju procjene korozijskog ponašanja u otopini s 3.5% – tnim masenim udjelom NaCl. Potenciodinamičke tehnike poput Tafel polarizacije i cikličke anodne polarizacije primijenjene su u cilju promatranja otpornosti na opću koroziju i sklonosti pojavi pitinga. Rezultati su pokazali da zona zavara ima katodni karakter u usporedbi s osnovnom legurom tako da je struja pasivacije veća, dok su piting potencijal Epit i repasivacijski potencijal Erp niži za uzorke izrađene iz zavarenih AlMgSi pločica. Ključne riječi: Korozija zavarene AlMgSi legure EN AW-6060; Kloridni medij Dalje >>>
LJILJANA RAŠKOVIĆ1, DUŠICA SAMARDŽIĆ2 ,BRATISLAV MILOŠEVIĆ2
Originalni naučni rad UDC:620.197.6
Vodorazredivi dvokomponentni poliuretanski premazi u zaštiti naoružanja i vojne opreme
Vodorazredivi dvokomponentni poliuretanski premazi predstavljaju najnoviju tehnologiju u idustriji boja i lakova. Ekološki su prihvaljivi, jer se za proizvodnju i primenu u premazima koristi voda umesto organskih rastvarača. Poznato je, da se u industrijski razvijenim zemljama, ova tehnologija dokazala u zaštiti automobila, aviona, energetskih i drugih industrijskih postrojenja. U tom cilju istraživane su mogućnosti da se ova tehnologija primeni u zaštiti naoružanja i vojne opreme. U ovom radu urađen je nov komponentni sastav premaza i modifikovan tehnološki postupak izrade, kako bi se ostvarili osnovni zahtevi antikorozionih i maskirnih svojstava u vodorazredivim dvokomponentnim poliuretanskim premazima. Premazi, razvijeni po novoj tehnologiji maskirnih boja (zelena svetla, braon i crna) ispitivani su po standardima odbrane SORS 1564/03 i SORS 8655/11. Pored standardnog ispitivanja, izvršeno je i ispitivanje zaštitnih sistema sa čisto vodorazredivim bojama i konbinovanih zaštitnih sistema sa vodorazredivim i bojama na bazi organskih rastvarača. Dobijeni rezultati ukazuju da su Vodorazredive dvokomponentne poliuretanske pokrivne maskirne boje zadovoljile zahteve kvaliteta pokrivne boje, namenjene za antikorozionu i maskirnu zaštitu naoružanja i vojne opreme.Rezultati ispitivanja zaštitnih sistema, pokazali su da ispitivani sistemi poseduju zadovoljavajući nivo kvaliteta fizičko- mehaničkih karakteristika, hemijske postojanosti i zaštitne sposobnosti. Rezultati ispitivanja konbinovanih sistema ukazuju na dobru kompatibilnost ispitivanih vodorazredivih boja i boja na bazi organskih rastvarača. Ključne reči: Vodorazredivi dvokomponentni poliuretani, umrežavanje, maskirni pigmenti, refleksija. Dalje >>>
Waterborn two-pack urethane coatings for protection of weapon and military equipment
Waterborn two-pack urethane coatings represent innovative technology in paints and coatings industry. Since the water is replacing volatile organic solvents in production and application processes, their ecological acceptance is unquestionable. It is well known that this technology is approved as superior for corrosion protection in energetic and industrial plants as well as in automotive and aircraft industries of developed countries. With such idea, the possibility of application of this technology for protection of military equipment has been investigated. In work presented in this paper, the new component formulation was designed and technology parameters were modified in manner to confirme the predefined requests for anticorrosive and camouflage properties of waterborne two-pack urethane coatings. Coatings developed according to approved scheme of camouflage painting (light green, brown and black) were submitted to laboratory testing according to military standards SORS 1564/03 and SORS 8655/11. Besides the standardized testing of single coatings, the protective properties of complex, hybrid coatings systems, composed with both, waterborne and conventional paints, were tested. Results implicate that waterborne two-pack urethane finish coatings satisfy the quality requests for finish coatings for anticorrosion and camouflage protection of military equipment. Results of protective paint systems composed of waterborne coatings show their satisfactory level of physical-mechanical properties, chemical stability and protective ability. Test results of hybrid systems, combined of, waterborne and conventional paints approve their good compatibility,
Key words: waterborn two-pack urethane, camouflage pigments, spectral reflectance refleksija More >>>
DRITAN PRIFTI1, MARJOLA PRIFTI2
Scientific paper UDC:666.5:553.6
Tuffs and kaolins areas evaluation for use as pozzolanic materials
Various tuffs and kaolin’s were evaluated for use in cement as pozzolanic additives. These materials were analyzed for chemical and mineralogical composition, reactive Si content and also were used for the production and testing of blended cements. The JOMEN tuffs, that seem to exist in significant reserves, already appear to be problematic due to their low reactive SiO2 content. The kaolin samples that were studied included those from the KORTHPULA, VIG and DEJAI areas. The search for suitable tuffs materials is now focused on the JOMEN area. The KORTHPULA kaolin had a high reactive silica content and could be considered as a potential pozzolanic additive. About the kaolins, the above conclusions were based on spot surface samples; the suitability of the kaolins as pozzolanic additives will need to be verified based on samples of core drilling that is planned for the near future. Key words: tuff, kaolin, pozzolanic additives, cement. More >>>
TUFOVI I KAOLINI IZ RAZLIČITIH OBLASTI ZA UPOTREBU KAO POCOLANSKI MATERIJALI
Razni tufovi i kaolini bili su razmatrani za upotrebu u cementnoj industriji kao pocolanski aditivi. Ovi materijali su analizirani na hemijski i mineraloški sastav, sadržaj reaktivnog Si, a takođe, su korišćeni za proizvodnju i testiranje raznih mešavina cementa. Tufovi iz JOMENSKE oblasti, koji postoje u značajnim rezervama, problematični su zbog niskog sadržaja reaktivnog SiO2. Uzorci kaolina, koji su proučavani, uzeti su iz oblasti KORTHPULA, VIG i DEJAI. Potraga za odgovarajućim tuf- materijalima je sada fokusirana na JOMEN oblasti. Kaolin iz KORTHPULA ima visok sadržaj reaktivnog Si i može se smatrati kao potencijalni pocolanski aditiv. Navedeni zaključci o podobnosti kaolina, kao pocolanskog aditiva iz ovih oblasti, na osnovu uzoraka sa površine zemljišta, moraće da se verifikuju na osnovu uzoraka uzetih sa većih dubina, koji su planirani za blisku budućnost.
Ključne reči: tuf, kaolin, pocolanski aditiv, cement. Dalje >>>
MARIO NIKOLA MUŽEK* , JELICA ZELIĆ
Scientific paper UDC:628.44:504.3.054
The effect of alkali activator on the development of mechanical properties of fly ash based geopolymer
The alkali activation of fly ash is a physical-chemical process of mixing fly ash with alkaline activators in order to produce materials with high mechanical properties – geopolymers. Three types of geopolymers were synthesized. The same fly ash was used in all the samples, but the alkali activator has been changed: water glass (sample A), sodium hydroxide (sample B) and combination of water glass and sodium hydroxide (sample C). After preparation, all samples were thermally cured in the laboratory oven at the temperature of 85 °C for 24 hours. Mechanical strengths were measured after 3, 7 and 28 days, and during that period of 28 days all the samples were hermetically sealed and stored at room temperature. The results obtained indicate that, geopolymer, synthesized by mixing fly ash with the combination of water glass and sodium hydroxide as alkaline activator, developed the highest compressive strengths during all period of interest, about 21.23 MPa at the age of 3 days and 21.28 MPa at the age of 7 days, which then reached 22.52 MPa after 28 days of curing at room temperature. Key words: geopolymers, alkali activator, compressive strengths. More >>>
Uticaj alkalnog aktivatora na razvoj mehaničkih karakteristika letećeg pepela na geopolimer
Alkalna aktivacija letećeg pepela predstavlja fizikalno-kemijski proces miješanja letećeg pepela sa alkalnim aktivatorima kako bi se proizveo materijal visokih mehaničkih čvrstoća – geopolimer. Sintetizirane su tri vrste geopolimera. Kod svih sinteza koristio se isti leteći pepeo, dok se mijenjala samo vrsta alkalnog aktivatora: vodeno staklo (uzorak A), natrijev hidroksid (uzorak B) i kombinacija vodenog stakla i natrijevog hidroksida (uzorak C). Nakon sinteze, svi uzorci su podvrgnuti toplinskoj obradi u trajanju od 24 sata u laboratorijskoj peći na temperaturi od 85 °C. Mehaničke čvrstoće su testirane nakon 3, 7 i 28 dana njegovanja. U tom periodu od 28 dana svi uzorci su hermetički njegovani pri sobnoj temperaturi. Geopolimer sintetiziran miješanjem letećeg pepela sa kombinacijom vodenog stakla i natrijevog hidroksida, kao alkalnog aktivatora, je razvio najviše mehaničke čvrstoće tijekom cijelog perioda ispitivanja: 21.23. MPa nakon 3 dana, 21.28 MPa nakon 7 dana i, konačno, 22.52 MPa nakon 28 dana njegovanja pri sobnoj temperaturi.
Ključne riječi: geopolimeri, alkalni aktivator, mehaničke čvrstoće. Dalje >>>
IRINA FIERASCU1, ROMULUS DIMA2, RADU CLAUDIU FIERASCU3
Scientific paper UDC:620.197.2 :729
Natural extracts for solving the issue of biodeterioration of the artefacts
The biodeterioration of the artefacts is a worldwide problem. Each culture’s cultural heritage is practically an act of identity; the way it is preserved is an important indicator of the degree of civilization of that community.All the artefacts (organic, inorganic or mixed) are exposed to various environmental conditions (temperature, pH, humidity, aerobic or anaerobic conditions, etc) that can lead to mould growth. The growth of microorganisms on the artefacts deteriorates theme in various ways (crusts, patina, staining, discoloration, mechanical damage, fouling, soiling, etc.) and leads to tremendous economic and aesthetic loss. The fungal species found in the environment that contaminates objects (Aspergillus, Penicillium, Cladosporium, Aureobasidium, Mucor, etc.) are commonly referred to as environmental mould.The aim of this investigation is the valorification of some natural selective extracts from plants native in Romania (Allium ursinum and Paeonia peregrina var. romanica) with antifungal properties for biological decontaminations of artefacts.
Key words: natural extracts, artefacts, biodeterioration. More >>>
Prirodni ekstrakti za rešavanje pitanja biostarenja predmeta
Biostarenje predmeta je svetski problem. Kulturno nasleđe svake kulture je praktično čin identiteta; način na koji je sačuvano je važan pokazatelj stepena civilizacije te zajednice.Svi predmeti (organski, neorganski ili mešoviti) su izloženi različitim uslovima dejstva sredine (temperatura, pH, vlaga, aerobni ili anaerobni uslovi, itd) koji mogu dovesti do rasta buđi. Rast mikroorganizama na predmetima pogoršava ovu pojavu na razne načine (koru, patina, bojenja, diskoloracija, mehanička oštećenja, zaprljanosti, oraštaji, itd), i dovodi do ogromnog ekonomskog i estetskog gubitka. Specijalne vrste gljiva pronađene u sredinama koje kontaminira objekte (Aspergillus, Penicillium, Cladosporium, Aureobasidium, Mucor, etc.) se obično naziva ekološki kalup. Cilj ovog istraživanja je valorifikacija nekih prirodnih ekstrakata iz biljaka poreklom iz Rumunije (Allium ursinum and Paeonia peregrina var. romanica) sa antigljivičnim svojstvima biološke decontaminacije predmeta. Ključne reči: prirodni ekstrakti, predmeti, biostarenje. Dalje >>>
BORISLAV MALINOVIĆ1, JOVO MANDIĆ1, MIOMIR PAVLOVIĆ2, MILORAD TOMIĆ2
Originalni naučni rad UDC :628.16:504.4.054
Smanjenje HPK-vrijednosti otpadnih voda anodnom oksidacijom u industriji poludisperzija i disperzija
Otpadne vode industrije poludisperzija i disperzija (boja) sadrže znatne količine suspendovanih neorganskih i organskih čestica (pigmenti, punila i razni dodaci). U radu je opisana upotreba anodne oksidacije kao jedan od mogućih postupaka za eliminaciju organskih i neorganskih materija u otpadnim vodama kroz direktno oduzimanje elektrona na anodi ili indirektno obrazovanjem aktivnog kiseonika, odnosno OH–radikala. Korištene su čelične i aluminijumske elektrode, a efikasnost uklanjanja HPK-vrijednosti se povećava sa vremenom elektrolize i primjenom aluminijumske elektrode uz povećanje provodljivosti rastvora dodatkom H2SO4. Ključne riječi: anodna oksidacija, HPK-vrijednost, poludisperzija, disperzija, otpadne vode. Dalje >>>
REDUCTION OF COD-VALUE OF WASTEWATER BY ANODIC OXIDATION IN INDUSTRY OF SEMI-DISPERSION AND DISPERSION
Wastewater industry semi-dispersion and dispersion (dye) contain considerable amounts of suspended inorganic and organic particles (pigments, fillers or additives). This paper describes the use of anodic oxidation as one of the possible procedures for the elimination of organic and inorganic substances in wastewater by directly electrochemically take electrons on the anode, or indirectly, forming of active oxygen or OH-radicals. Were used steel and aluminum electrodes and removal efficiency of COD-value increases with time of electrolysis and using aluminum electrodes with increasing conductivity of solution addition H2SO4.
Key words: anodic oxidation, COD-value, semi-dispersion, dispersion, waste water. More >>>
MIODRAG SMELCEROVIC, NOVICA DJORDJEVIC, DRAGAN DJORDJEVIC
Scientific paper UDC:628.44:504.3.054
Kinetics of reactive dyes adsorption on the bottom ashes
The aim of this paper is to present the adsorption kinetics of a typical textile reactive dye on the bottom waste ash, which can lead to valuable data related to the possibility of wider application, for example with purification of the dyed waste waters. Sorption kinetics, which describes the rate of adsorption of pollutants (dye), is one of the most important characteristic that defines the efficiency of sorption and the ability to use the adsorbent in controlling water pollution. In order to investigate the mechanism of adsorption of reactive dyes from the textile industry on the bottom ashes from city heating station by coal combustion, some characteristic constants of sorption are determined using Lagergren’s equation for the pseudo-first and pseudo-second order. United, kinetic models of pseudo-first order and pseudo-second order can provide a simple but satisfactory explanation of the adsorption process for a reactive dye. Key words: adsorption, ashes, kinetics, Lagergren’s equation, reactive dye. More >>>
KINETIKA ADSORPCIJE REAKTIVNE BOJE NA KOTLOVSKOM PEPELU
Cilj ovog rada je da predstavi kinetiku adsorpcije tipične reaktivne boje za tekstil na kotlovskom otpadnom pepelu, što može dovesti do dragocenih podataka koji se odnose na mogućnost šire primene, na primer, za prečišćavanje obojenih otpadnih voda. Kinetika sorpcije, koja opisuje brzinu adsorpcije zagađivača (boja) je jedna od najvažnijih karakteristika koja definiše efikasnost sorpcije i mogućnost korišćenja adsorbenta u kontroli zagađenja voda. U cilju istraživanja mehanizma adsorpcije reaktivne boje iz tekstilne industrije na kotlovski pepeo dobijen posle sagorevanja uglja iz gradske toplane, određene su karakteristične konstante sorpcije korišćenjem Lagergren-ove jednačine za pseudo-prvi i pseudo-drugi red. Zajedno, kinetički modeli pseudo-prvog i pseudo-drugog reda mogu obezbediti jednostavno ali zadovoljavajuće objašnjenje procesa adsorpcije reaktivne boje. Ključne reči: adsorpcija, pepeo, kinetika, Lagergren-ova jednačina, reaktivna boja. Dalje >>>
SREĆKO MANASIJEVIĆ1, SRĐAN MARKOVIĆ2 , RADOMIR RADIŠA1
Originalni naučni rad UDC:621.437
Primena novih tehnologija u cilju poboljšanja eksploatacionih svojstava klipova sus motora od aluminijumskih legura
U ovom radu prezentovana je primena novih tehnologija u cilju poboljšanja eksploatacionih svojstava klipova SUS motora izrađenih od aluminijumskih legura. Savremeni razvoj SUS motora, posebno u slučaju sportskih automobila, nameće potrebu za postizanjem maksimalne snage, što pak ekstremno povećava opterećenje pojedinih delova klipa. Pokazalo se da tvrdoća i otpornost na habanje, inače svojstveni legurama aluminijuma, na ovako visokim temperaturama i ekstremnim eksploatacionim uslovima, nisu zadovoljavajuće. Ideja je da se najopterećeniji delovi klipa zaštite kompozitima sa aluminijumskom matricom, što što bi predstavljalo rešenje ovog problema. Cilj ovog rada je da izvrši pregled postignutih rezulata istraživanja u ovoj oblasti. Ključne reči: aluminijumske klipne legure, kompozitni materijali. Dalje >>>
APPLICATION OF NEW TECHNOLOGIES TO IMPROVE THE EXPLOITATION PROPERTIES OF COMBUSTION ENGINE PISTONS OF ALUMINIUM ALLOYS
This paper presents the application of new technologies in order to improve the exploitation properties of pistons for combustion engines made of aluminum alloy. Modern development of internal combustion engines, especially in the case of sports cars, imposed by the need to achieve maximum power, which in turn extremely increases the load on the individual parts of the piston. It has been shown that the hardness and wear resistance, otherwise inherent in aluminum alloys, for such high temperatures and extreme service conditions are not satisfactory. The idea is to protect the most burdened parts piston with aluminum matrix composites, which would be a solution to this problem. The aim of this paper is to review the research results achieved in this area. Key words: aluminum piston alloys, composite materials. More >>>
MIROLJUB TRIFUNOVIC1, NOVICA GRUJIC2, Originalni naučni rad
BRANISLAV NEDELJKOVIC3 UDC:621.8
Kompoziti sa matricom na bazi legure CuZn37 za izradu frikcionih elemenata
U radu su prikazani rezultati ispitivanja triboloških i mehaničkih osobina laboratorijskog kompozita sa matricom na bazi legure CuZn37 (MS 63) ojačanom česticama čeličnog praha propisanih karakteristika – hemijskog sastava, granulacije i koncetracije. Dobijeni rezultati ukazuju da je ideja o projektovanoj vrsti kompozita interesantna i da treba nastaviti rad na pronalaženju optimalne kombinacije metalmatričnog komnpozita (MMK), koji bi mogao da se koristi za izradu frikcionih elemenata poboljšanih triboloških i mehaničkuh karakteristika. Ključne reči: kompozit, ingot metalurgija, frikcioni elementi, tribološka svojstva, mehanička svojstva. Dalje >>>
COMPOSITE WITH A MATRIX-BASED ALLOYS CuZn37 FOR MAKING FRICTION ELEMENTS
This paper presents results obtained by testing tribological and mechanical properties of laboratory composite consisting of matrix based on CuZn37 (MS 63) alloy reinforced by steel powder particles with prescribed characteristics – chemical composition, granulation and concentration. Obtained results imply that the idea about such a composite is interesting and that efforts towards finding the optimal combination of metal matrix composite (MMC), which could be used for production of friction elements characterized by improved tribological and mechanical properties, should be continued. Key words: composite, ingot metallurgy, friction elements, tribological properties, mechanical properties. More >>>
ŽIVČE ŠARKOĆEVIĆ1, MIODRAG ARSIĆ2, Originalni naučni rad
MARKO RAKIN3, BOJAN MEĐO3, MILAN MIŠIĆ1 UDC:620.197.7:622.24
Otpornost na koroziju zavarenih cevi u naftnim bušotinama
Čelične cevi u naftnim i gasnim bušotinama su kontinuirano izložene procesu korozije potpomognutom povišenim temperaturama i pritiscima, koji vladaju u unutrašnjosti cevi. Korozija može da dovede do značajnog smanjenja mehaničkih osobina čelika i zavarenog spoja što može pod nepovoljnim uslovima predstavljati uvod u lom cevi i to brže ukoliko su naprezanja veća. Otkazi zavarenih cevi u naftnim i gasnim bušotinama, nastali usled grešaka u izradi cevi i/ili njihovog oštećenja u eksploataciji, pored uticaja na pouzdanost i bezbednost u radu imaju i ekološki uticaj na okolinu, odnosno na kvalitet zemlje, vode i vazduha. Zaštitne zavarene cevi u naftnim bušotinama spadaju u visoko odgovorne konstrukcije koje su osetljive na koroziju. Zato je bitno poznavati preostalu čvrstoću cevi u slučaju pojave korozionog oštećenja. U radu su prikazani rezultati ispitivanja nivoa oštećenja čelika API J55, korišćenog za izradu zaštitnih cevi visokofrekventnim kontaktnim postupkom zavarivanja (VF). Ispitivana cev je povučena iz eksploatacije nakon približno 70 000 radnih sati (8 godina) u naftnoj bušotini. Eksperimentalna ispitivanja su izvršena na zaštitnim zavarenim cevima iz eksploatacije koje su zatvorene torisferičnim dancima, sa mehaničkom obradom simuluranim korozionim oštećenjima na spoljašnjoj površini cevi. Za određivanja otpornosti zaštitnih zavarenih cevi prema oštećenju izvršeno je merenje deformacija i izračunati su glavni normalni naponi. Primenom postupka ASME B31G, modifikovanog ASME B31G, izračunati su maksimalni pritisci oštećenih cevi. Ključne reči: zaštitne cevi, koroziono oštećenje, maksimalno dozvoljeni pritisak, visokofrekventno kontaktno zavarivanje. Dalje >>>
CORROSION RESISTANCE OF WELDED PIPE IN OIL WELLS
Steel pipes in oil and gas wells are continuously exposed to the process of corrosion-assisted elevated temperatures and pressures prevailing in the interior of the tube. Corrosion can lead to significant reduction of mechanical properties of steels and welded joints which may under unfavorable conditions, lead to breaking of pipes even faster if the stresses are higher. Failures of welded pipes in oil and gas wells, caused by errors in the preparation of tubes and / or their damage in service, in addition to the impact on the reliability and safety in the work and have environmental impacts on the environment and the quality of land, water and air. Protection of welded pipes in oil wells belong to the highly responsible structures that are susceptible to corrosion. It is therefore important to know the remaining strength of pipe in the event of corrosion damage. This paper presents the results of testing of damage API J55 steel, used for the production of protective high-frequency pipe welding contact (VF). Investigated tube was withdrawn from service after about 70 000 operating hours (8 years) in the oil rig. Experiments were performed on the protective welded pipes from service by the closed torispherical head, the mechanical treatment simulated by the corrosive damage to the outer surface of the tube. For determining the resistance of welded pipes to damage were measured and calculated deformations are the main normal stresses. The application of the ASME B31G, modified ASME B31G, calculate the maximum pressures of damaged pipes. Key words: casing pipes, corrosion defect, maximum allowed pressure, high frequency contact welding. More >>>
SUZANA ĐORĐEVIC1, STANA KOVAČEVIĆ2, Originalni naučni rad
LJUBIŠA NIKOLIĆ1, DRAGAN ĐORĐEVIĆ1 UDC:620.197.7
Zaštita pamučne pređe od naprezanja impregniranjem modifikovanim skrobom
Rad se bavi primenom modifikovanog skroba u zaštiti pamučne pređe od naprezanja koja se javljaju u toku procesa tkanja. Modifikovani skrob je kalem kopolimer dobijen od hidrolizovanog krompirovog skroba i akrilamida. FTIR spektri hidrolizovanog i kalemljenog skroba, svojim karakterističnim trakama apsorcije potvrđuju da je kalemljenje monomera uspešno obavljeno. Molarne mase istraživanih uzoraka hidrolizata i kopolimera pokazuju različitost i veće variranje, opseg 1×102 do 2×107 g/mol. Rezultati impregniranja pokazuju da obrađena pređa ima veću jačinu (čvrstoća) i slabije izduženje. Kalemljeni hidrolizovani skrob, kao sredstvo za zaštitu pamučne pređe, daje bolje rezultate nego nekalemljeni, naročito u pogledu ravnomernosti nanosa, mehaničkih pokazatelja pređe i lakšeg uklanjanja u naknadnom procesu pranja. Ključne reči: skrob, akrilamid, kalemljenje, impregniranje, pređa. Dalje >>>
Cotton yarns Protecting from tension by impregnation of modified starch
The paper deals with the application of modified starch in cotton yarns protecting from stresses that occur during the process of weaving. Modified starch is the graft copolymer obtained from hydrolyzed potato starch and acrylamide. FTIR spectra of the grafted and hydrolyzed starch, its characteristic absorption bands confirm that the grafting monomer successfully. Molecular weight of the investigated samples and hydrolyzed copolymers show greater variation and diversity, the range is 1×102 to 2×107 g/mol. The results show that the impregnation processed yarn has higher strength and lower elongation. Grafted hydrolyzed starch, as a means for the protection of cotton yarn, gives better results than ungrafted, especially in terms of uniformity of deposits, mechanical parameters of the yarn and easier to remove in the subsequent washing process. Key words: starch, acrylamide, grafting, impregnation, yarn. More >>>
VLADISLAV MATKOVIĆ, MIROSLAV SOKIĆ, Originalni naučni rad
BRANISLAV MARKOVIĆ UDC:620.284:628.16
Recikliranje opasnog otpada na bazi nikla iz industrije biljnih ulja
U radu su prikazani rezultati reciklaže opasnog otpada na bazi nikla koji nastaje u procesu hidrogenovanja ulja. Kataloizatori na bazi nikla se koriste za selektivno hidrogenovanje biljnih ulja visoke aktivnosti. Istrošeni katalizatori na bazi nikla su svrstani u kategoriju H11 opasnih materija, koji se nakon završenog procesa, trenutno deponuju na prostoru generatora i na taj način predstavljaju potencijalnu opasnost po životnu sredinu. Eksperimentalnim istraživanjima definisani su optimalni uslovi (temperatura, vreme, odnos Č:T) tehnološkog postupka reciklaže istrošenih katalizatora. Izdvajanjem nikla u obliku nikl-sulfata opasan otpad prelazi u kategoriju neopasnog, a dobijeni proizvod ima komercijalnu vrednost. Stepen iskorišćenja nikla je veći od 95%. Ključne reči: opasan otpad, istrošeni katalizatori, recikliranje nikla. Dalje >>>
Recycling of nickel based hazardous waste from the plant oils industry
The results obtained during the recycling of spent nickel based catalysts that generate in the oil hydrogenation process are presented. Nickel based catalysts are used for selective hydrogenation of the highly active plants oils. The used catalysts are classified in the H11 category of hazardous materials; they are deposited on the site and are potentially dangerous to the environment. Laboratory experimental research defined optimal conditions (temperature, time and solid-liquid ratio) and technological process of catalists recycling. Hazardous waste is being converted to the category of non-hazardous, and extracted nickel as nickel-sulphate represents commercial product. The degree of recovery of nickel is higher than 95%.
Key words: hazardous waste, used catalysts, nickel recycling. More >>>
VIOLETA D. MITIĆ1*. VESNA P. STANKOV- Originalni naučni rad
JOVANOVIĆ1, MARIJA D. ILIĆ1, SNEŽANA UDC:614.841:504.7.055
Č. JOVANOVIĆ1, SNEŽANA D. NIKOLIĆ-MANDIĆ2
Uticaj požara na sadržaj teških metala u biljkama i zemljištu
Požar koji se u leto 2007 godine desio na planini Vidlič u Srbiji opustošio je velike prostore pod sitnim rastinjem i šumom. Cilj ovog istraživanja bilo je ispitivanje uticaja požara na sadržaj teških metala u biljkama Aegopodium podagraria Hypericum perforatum i Chelidonium majus koje pripadaju familijama Apiaceae, Hypericaceae i Papaveraceae. Takođe, ispitivan je i sadržaj teških metala u uzorcima zemljišta na kojima su biljke rasle godinu dana nakon požara. Kao kontrolni materijal korišćeni su uzorci biljaka i zemljišta sa lokaliteta u neposrednoj blizini koji nije bio izložen dejstvu vatre. Sadržaj metala određivan je u ekstraktibilnoj, biodostupnoj i frakciji pseudototalnih katjona. Može se zaključiti da je sadržaj teških metala (Pb, Cd, Cu i Zn) najveći u frakciji pseudototalnih katjona, a najmanji u frakciji biodostupnih katjona. Koncentracije svih određivanih teških metala u svim frakcijama su uvek veće za uzorke zemljišta koja su bila izložena dejstvu požara osim u slučaju sadržaja cinka i bakra u esktraktibilnoj frakciji zemljišta biljaka A. podagraria i H. perfortum. Podzemni delovi svih ispitivanih biljaka koje su rasle na oba lokaliteta sadrže veću koncentraciju olova u odnosu na nadzemni deo. Sadržaj cinka je veći u uzorcima biljaka nego u uzorcima tla na kojem su biljke rasle. Nadzemni delovi sve tri ispitivane biljke sadrže nešto više bakra u odnosu na odgovarajuće podzemne delove biljaka. Podzemni delovi sve tri biljke sa lokaliteta koji nije bio izložen dejstvu vatre sadrže veće količine kadmijuma u odnosu na biljke sa lokaliteta koji je pretrpeo požar.
Ključne reči: metali u zemljištu, metali u biljkama, požar, Aegopodium podagraria, Hypericum perforatum, Chelidonium majus. Dalje >>>
Impact of the wild fire on the content of lead, zinc, copper and cadmium in soil and plant material
Wild fire occurred in the summer 2007 on the Vidlic Mountain (Serbia) overspreading a huge area of meadows and forests. The aim of the study was to investigate the effect of wild fire on the content of heavy metals in plants Aegopodium podagraria, Hypericum perforatum and Chelidonium majus belonging to the families Apiaceae, Hypericaceae and Papaveraceae. Also, we examined the content of heavy metals in soil samples on which the test plants grow a year after fire. As control samples was investigated by the appropriate plant material and soil from the site in the immediate vicinity that was not affected by the fire. Metal content in the soil was determined in the fractions of extractible, bioavailable and pseudo total cations. The content of all examined heavy metals (Pb, Cd, Cu and Zn) is the biggest in pseudo total cations fractions and the lowest in bioavailable cations fractions. The exception is the land on which the plant A. Podagraria grows, because the content of copper and zinc was the largest in the fraction of extractable cations. The concentration of heavy metals in all fractions was always higher in soil samples that were exposed to the fire, except in the extractible metal cations fractions of A. podagraria and H. perforatum. Lead is characterized by the highest concentration in the soil of all three plant species. The lead content was much greater in pseudo total cations fractions. The underground parts of plants that were grown on both locations have a higher concentration of lead in relation to the above-ground portion. The content of zinc was higher in the plant samples than in samples of soil where the plants are grown. Above-ground parts of all three examined plants contain more copper than the corresponding underground parts of the plant. The underground parts of examined plants from location that were not exposed to the fire have higher levels of cadmium than plants from the localities which suffered from the fire.
Key words: heavy metals in soil, heavy metals in plants, wildfire, Aegopodium podagraria, Hypericum perforatum, Chelidonium majus. More >>>
LJILJANA AVRAMOVIĆ*, MILE BUGARIN*, Originalni naučni rad
ZORAN STEVANOVIĆ*, LJUBIŠA OBRADOVIĆ*, UDC:628.16:622
MARKO JONOVIĆ**, RADOJKA JONOVIĆ*,
RADMILA MARKOVIĆ*
Uticaj rudničkog otpada iz RTB Bor na okolne vodotokove
Tokom više od jednog veka rudarenja u opštini Bor, različitim rudarskim i metalurškim aktivnostima, degradirano je više hiljada hektara šuma i oranica. Procenjuje se, da je do danas u Boru i okolini otkopano preko 200 miliona tona rude i oko 500 miliona tona raskrivke, pri čemu je proizvedeno oko 195 miliona tona flotacijske jalovine. Odloženi rudnički otpad od momenta odlaganja pa nadalje, pod uticajem atmosferilija predstavlja trajan izvor kiselih voda koje sa sobom nose rastvorene teške metale i zagađuju okolno zemljište, površinske vodotokove kao i podzemne vode. Zbog kontinualnog pojavljivanja kiselih rastvora javlja se konstantan negativan uticaja na površinske i podzemne vodotokove kao i na njihovo priobalje. Predmet rada je analiza stvarnog stanja ugroženih lokacija i njihova kategorizacija prema stepenu kontaminacije štetnim elementima.
Ključne reči:rudnički otpad, vodotokovi, jalovina. Dalje >>>
THE INFLUENCE OF THE DEPOSITED MINING WASTE FROM RTB BOR ON THE SURROUNDING WATERWAYS
For more than a century of mining in the municipality of Bor, various mining and metallurgical activities, degradation of thousands of hectares of forests and fields. It is estimated that up to now in Bor and its surroundings have been excavated over 200 million tons of ore and 500 million tonnes of overburden, where he produced about 195 million tons of tailings. Deferred mining waste disposal from the moment onwards, under the influence of environmental factors is an ongoing source of acid waters carry dissolved heavy metals and pollute the surrounding soil, surface water and groundwater. Due to the continuous occurrence of acid solutions appears constant negative impact on surface and ground water flows as well as their watersheds. The paper analyzes the actual state of endangered locations and their categorization according to the degree of contamination of harmful elements.
Key words: mining waste, waterways, tailings. More >>>
VELJKO ĐUKIĆ Stručni rad
UDC:351.777.613:691
Mogućnosti upravljanja građevinskim otpadom u Republici Srpskoj
Rad se zasniva na zadacima uspostavljanja sistema kontrolisanog upravljanja građevinskim otpadom uz evidenciju količina, vrsta i sastava građevinskog otpada, izbjegavanju prevenciji nastajanja, smanjivanju količina koje se odlažu, reciklaži, te donošenju zakonskih obaveza i propisa o prikupljanju i zbrinjavanju građevinskog otpada u toku izgradnje, renoviranja ili rušenja građevina.
Ključne riječi: građevinski otpad, zaštita životne sredine, reciklaža. Dalje >>>
CONSTRUCTION WASTE MANAGEMENT POSSIBILITY IN REPUBLIC OF SRPSKA
The work is based on the task of establishing a system of controlled management of construction waste to the record of the amount, type and composition of construction waste, avoidance of preventing waste, reducing the amount to be disposed of, recycling, and making the legislation and regulations on the collection and disposal of construction waste during the construction, renovation or demolition of buildings.
Key words: construction waste, environmental protection, recycling. More >>>
