Zaštita materijala 2010

BROJ 1

M.CENOUI¹, I. HIMER¹, R. TOUIR¹, M. EBN TOUHAMI¹ A. DERMAJ¹, N. HAJJAJI¹, H. EL KAFSSAOUI²

Scientific paper[PDF]
UDC:620.197.3:669.12/.13

Synergistic influence of molybdate ions on the inhibition of corrosion and scale of ordinary steel in cooling water system by new organic compound

This work was carried out to study the inhibition of corrosion of ordinary steel in cooling water system solution by a multi-component. The inhibitive formulation was composed of 2- (2-thio-dodecyl-5-methyl-1,3,4-triazol)yl acetic acid (TDMTAA) associated with molybdate ions. The obtained results lead that TDMTAA inhibits the corrosion of ordinary steel in the considered medium. The corresponding inhibition efficiency increases by increasing of inhibitor concentration and also by addition of molybdate ions. The Values of the synergism parameter (S_θ) indicate the fact that the enhanced inhibition efficiency in the presence of molybdate ions is only due to synergism and there is a definite contribution from the inhibitor molecule, which are adsorbed by coulombic interaction on the metal surface, where molybdate ions are already adsorbed and thus reduce the corrosion rate. The inhibition efficiency of mixture increases by increasing of temperature, pH and immersion time and leads a maximum of 99%.

Keywords: Corrosion and inhibition, TDMTAA, Molybdate, Synergistic, Polarization curves, Ordinary steel, Cooling water system.

 

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NOREEN ANTONY¹, H. BENITA SHERINE², SUSAI RAJENDRAN³

Scientific paper[PDF]
UDC:620.197.3:669.146.97

Investigation of the inhibiting effect of nano film by sodium meta silicate- Zn²⁺ system on the corrosion of carbon steel in neutral chloride solution

 

The inhibition of corrosion of carbon steel in 120 ppm chloride solution by Sodium meta silicate (SMS) in the presence and absence of Zn²⁺ ions is studied. The tests performed to measure the efficiencies of these substances reveal that 150 ppm of SMS and 75 ppm of Zn²⁺ gives 82 % inhibition efficiency. Scanning probe microscopic analysis and AC impedance show the formation of thin film on the surface of the metal. FTIR spectroscopy suggests that the film is formed by iron –inhibitor complex and Zn (OH)₂. Potentiodynamic studies reveal that the inhibitor system is of mixed type controlling the cathodic processes predominantly. An attempt was made to explain the mechanism based on the above studies.

Key words: Corrosion of carbon steel, sodium meta silicate, zinc ions, chloride solution

 

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ORCE SPASOVSKI¹, TRAJCE MITEV¹ ,MARINKO EFTIMOV², DIMITAR PETROV²

Scientific paper [PDF]
UDC:504.75.054/.055:663.646(497.17)

The influence of the exploatation of the gas CO₂ and mineralwater from vicinity “Popojci” village Dolno Orizari – Bitola on the living environment

The pollution of the underground water, concerning their easy injurance is the most important problem that the civilization is facing, present days. The protection of the surface and underground water, soil, the air is most important thing, which in the present civilization is left to be done and to release pure resources of clean drinking water for the next generations. 

Normally, every additional motive power on this space from Pelagonian basin should be expected to bring micro and macro changes of the living environment, which can arose multiple consequences first of all in the harmless of the underground water.
It should be mentioned that every drop of dirt that falls on the surface of the soil will migrate in the depth of the soil.
In this paper, gained results from the research and the quality of the mineral water and the gas CO2 are described, as well as the way of the exploitation of the mineral water and the influence of the exploitation on the living environment.

Key words: underground mineral water, gas CO2, Popojci, Dolno Orizari, living environment, pollution.

 

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SANJA G. ERAKOVIĆ¹, VLADIMIR V. PANIĆ² ,BOJAN M. JOKIĆ¹, SANJA I. STEVANOVIĆ², VESNA B. MIŠKOVIĆ-STANKOVIĆ¹

Originalni naučni rad [PDF]
UDC:669.295.864-492

Prevlake hidroksiapatita na nanotubama oksida titana

Cilj ovog rada je dobijanje nanotubularnog TiO2 sloja na titanu postupkom anodizacije i ispitivanje parametara elektroforetskog taloženja prevlaka hidroksiapatita (HAP) na formiranom međusloju nanotubularnog TiO2. Pokazano je da anodizacija titana u elektrolitu koji sadrži fluoridne jone omogućava formiranje nanotuba TiO2 na površini titana. Površina titana modifikovana nanotubama TiO2 je korišćena kao podloga za kataforetsko taloženje prevlaka hidroksiapatita iz etanolske suspenzije. Kisela sredina za anodizaciju titana omogućava dobijanje kraćih nanotuba koje su se pokazale kao bolja podloga za nanošenje HAP prevlaka. Nakon anodizacije, titanske pločice su termički tretirane da bi se dobila definisanija struktura nanotubularnog TiO2 sloja. Kataforetskim taloženjem dobijene su dobro prianjajuće i kompaktne HAP prevlake na termički tretiranim i netretiranim anodiziranim uzorcima. Rezultati pokazuju da pri vremenima taloženja dužim od 45 min dolazi do smanjenja adhezije prevlake hidroksiapatita.

Ključne reči: anodizacija, nanotube TiO2, elektroforetsko taloženje, prevlake, hidroksiapatit

 

Hydroxyapatite coatings on TiO2 nanotubes

The aim of this work was to obtain nanotubular TiO2 layer by anodization of titanium substrate, and to prepare hydroxyapatite (HAP) coatings by electrophoretic deposition over nanotubular TiO2 layer. The presence of fluoride ion in the electrolyte for anodization causes the formation of TiO2 nanotubes. The Ti surface modified with TiO2 nanotubes was used for fabrication of HAP coatings by electrophoretic deposition. Acidic medium provides formation of short nanotubes which are more suitable for deposition of HAP coatings. Ti plates were thermally treated after anodization in order to gain more defined structure of nanotubular TiO2 layer. Compact HAP coatings with good adhesion were produced by electrophoretic deposition on thermally treated and untreated anodized specimens. The results showed that coating mass increases with deposition time, but prolongation of the deposition time causes the decrease of HAP coating adhesion.

Key words: anodization, TiO2 nanotubes, electrophoretic deposition, coatings, hydroxyapatite

 

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ANTO S. GAJIĆ¹, MILORAD V. TOMIĆ², LJUBICA J. PAVLOVIĆ³, MIOMIR G. PAVLOVIĆ²

Originalni naučni rad [PDF]
UDC:620.193.2:620.48

Kvalitet vode kao jedan od mogućih uzročnika korozije u termoenergetskim postrojenjima

Oštećenja i njima izazvani otkazi termoenergetskih postrojenja u velikom broju su izazvani usled neadekvatnog kvaliteta napojne vode, usled čega se odvijaju različiti tipovi korozionih procesa. Voda je dobar rastvarač i u svom hemijskom sastavu sadrži i veliki broj primesa koje joj daju veoma složen hemijski sastav. Upravo zbog toga sirova voda pruža mogućnost odvijanja niza kompleksnih i različitih korozionih procesa. Zbog toga je vodu, kao osnovni fluid u termoenergetskim postrojenjima, potrebno podvrgnuti adekvatnoj pripremi kako bi se korozioni procesi sveli na minimum i mogli kon­trolisati. Neophodno je u svakom pojedinačnom slučaju odrediti delujući mehanizam korozije i uzroč­nike koji ga izazivaju. U radu su prikazani osnovni uzroci koji dovde do korozije termoenergetskih postrojenja. Da bi se ostvario visok nivo pouzdanosti rada termoelektrana i postigao njihov očekivani radni vek mora se obezbediti visok kvalitet vode, s obzirom na njen značaj za pojavu korozije.

Ključne reči: kvalitet vode, korozija, kotao, para, termoenergetsko postrojenje, kamenac, kotlovski mulj, koagulacija, taloženje

 

Water quality as one of the possible causative agents of Corrosion in THERMAL power plants

Damage and cancellations of thermal power plants in large numbers are caused due to an unadequate quality of feed water, which occur due to different types of corrosion processes. Water is a good solvent and its chemical composition contains a large number of ingridients which provide its very complex chemical composition. That is the reason why raw water provides possibilities of complex and different corrosion processes. Since water is a basic fluid in power plants, it needs adequate preparation in order to minimize corrosion processes and to control them. It is necessary in each particular case to determine the acting mechanism of corrosion and sources that cause it. This paper presents the basic causes that lead to corrosion in thermal power plants. To achieve a high level of reliability of power plants and achieve their expected lifetime it is necessary to provide high quality water, due to its importance for the occurrence of corrosion.

Key words: water quality, corrosion, boiler, steam, thermal power plants, scale, boiler sludge, coagulation, deposition

 

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BISENIJA PETROVIĆ¹, VOJKA GARDIĆ²

Pregledni rad [PDF]
UDC:669.586.5.004.8

Razvoj tehnologije reciklaže metala iz opasnog otpada pogona za toplo cinkovanje

U galvanskom postupku toplog cinkovanja dolazi do stvaranja novog proizvoda od čelika zaštićenog od korozije prevlakom cinka, a  uz to dolazi do pojave pet vrsta nus proizvoda: cink šljake, cink pepela, cinkove pare, otpadnih rastvora i otpadnih voda. Rešavanjem otpadnih rastvora i otpadnih voda nastaju muljevi, kao dodatni nus proizvodi. Svi navedeni nus proizvodi pripadaju otpadu i to uglavnom opasnom otpadu. Upravljanje ovom vrstom otpada složen je i delikatan posao. Regeneracija i reciklaža navedenih otpada su veoma poželjni obzirom da sadrže značajne količine metala, na prvom mestu cinka. U ovom radu su prikazani pravci razvoja tehnologije reciklaže metala iz opasnog otpada.

Ključne reči: regeneracija, reciklaža, toplo cinkovanje, opasni otpad, cink

THE DEVELOPMENT OF TECHNOLOGY METAL RECOVERY FROM HAZARDOUS WASTE IN HOT DIP GALVANIZING PLANTS

In hot-dip galvanizing plants to carry out new product of steel with zinc coating for corrosion protection, but and five type of byproducts are formed: zinc dross, zinc ash, zinc fumes, spent solutions and waste waters. The sludges as byproducts to begin after treatments of waste water and spent solutions. All prezented byproducts belongs to wastes and mainly to hazardous wastes. The management of this type waste are a complicated and delicated work. The regeneration and recycling of prezented waste are desirable. In this work are presented development trend of recovery technology metal from hazardous waste.

Key wods: regeneration, recycling, hot dip galvanizing, hazardous waste, zinc

 

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SLAĐANA ALAGIĆ, SNEŽANA UROŠEVIĆ

Pregledni rad [PDF]
UDC:620.197.6/.7:614.841.33

Organobromni usporivači gorenja – supstance nepoželjne za zaštitu materijala od dejstva vatre

Iako se proizvodnja i potrošnja organobromnih jedinjenja kao usporivača gorenja (Brominated Flame Retardants, BFRs) veoma razlikuju u različitim delovima sveta, ove supstance predstavljaju glavne industrijske hemikalije čija je upotreba dramatično porasla tokom poslednjih 30 godina. Organobromni usporivači gorenja se koriste u preveniranju procesa gorenja kod različitih materijala (širok spektar polimera u odeći, nameštaju, elektronici, vozilima i kompjuterima), gde pokazuju direktnu i očiglednu korist. Međutim, saznanja o njihovoj postojanosti, bioakumulaciji i potencijalnoj toksičnosti za životinje i ljude dovela su do povećanja zabrinutosti kod stručne i naučne javnosti. Tokom poslednjih 20 godina, mnoge studije su bile sprovedene kako bi se definisalo kako i gde ove hemikalije ulaze u životnu sredinu, kao i šta se sa njima dešava kada jednom u nju i dospeju. Iako još uvek postoje neslaganja po ovim pitanjima, kao i oko njihovih toksikoloških svojstava, ekoloških rizika, kao i rizika po ljudsko zdravlje, dve klase BFRs: polibromovani difenil-etri (PBDEs) i polibromovani bifenili (PBB), jesu supstance koje su danas zabranjene za upotrebu u mnogim zemljama sveta. Srbija takođe pokazuje nastojanje da uspostavi ograničenja usklađena sa Evropskim zakonima. Pažnja istraživača danas, usmerena je u pravcu potrage za novim materijalima koji bi trebali uspešno da zamene BFRs. Najbolji rezultati postižu se sa nano-materijalima.

Ključne reči: Organobromni usporivači gorenja, zaštita od požara, životna sredina, zakonodavstvo

 

BROMINATED FLAME RETARDANTS – UNWELCOME MATERIALS IN FIRE PROTECTION

Even thoght the production and the use patterns of bromi­nated flame retardants (BFRs) are very different in various parts of the world, these substances represent major industrial chemicals whose use has increased dramatically over the past 30 years. BFRs are used to pre­vent burning in various materials (wide variety of polymers in clothing and furniture, to electronics, vehicles and computers) and thus can have a direct and obvi­ous benefit. However, knowledges of their persistence, bioaccumu­lation, and potential for toxicity, both in ani­mals and in humans are raised concerns among experts and scientists. Over the past 20 years, many studies have been conducted to define how and where these chemicals are being released into the environment, and what is happening to them once they enter the environment. Even thought there is still some disagreements about these issues, and also about their toxicological properties, human health risks and ecological risks, two classes of BFRs: polybrominated diphenyl ethers (PBDEs) and polybrominated biphenyls (PBBs) are banned chemicals in many countries of the World now. Serbia also shows intention to establish restrictions harmonized with European law. Researchers attention today is on the new kind of materials which can replace BFRs successfuly. The best results are with nanomaterials.

Key words: Brominated Flame Retardants, fire protection, environment, legislation

 

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SIMON BASTL, MATJAŽ PEČAR

Stručni rad [PDF]
UDC:669.586.5

Opis postupka toplog cinkovanja

Počeci toplog cinkovanja, kao postupak anti­korozivne  zaštite proizvoda od gvožđa i čelika potiču iz 16. i 17. veka, kada prvi put nailazimo na trgovanje cinkom u Kini i Severnoj Indiji. Tada počinje da se koristi izraz  »korozija«. Godine 1742 Francuz Maloun pronalazi postupak u kome gvožđe umače u rastopljeni cink i tako ga štiti prvlakom od cinka. Postupak toplog cinkovanja patentirao je 1837. god. Sorel.

Nakon godine 1840 počinju da rastu prve cinkare u Francuskoj, Engleskoj i Nemačkoj. Kod toplog cinkovanja se površinsko očišćeni čelični elemenat potapa u rastopljeni cink i tako nastaje pocinkovana prevlaka, koja ima izuzetne antikorozivne karak­teristike.

 

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BROJ 2

 

KOZETA VASO,¹ ,  MEVLUDE DEMA,¹, JOZEFITA MARKU ²

Scientific paper [PDF]
UDC:620.197.6:665.32

Improvement of the physico-chemical characteristics of sunflower oil through thermo-chemical processing and its use in the anticorrosive paints 

Sunflower oil, soya oil and maize oil are semi drying oils but they cannot be used in the paint industry without being processed first. There are different methods to process these oils in order to improve their physico-chemical characteristics. This article deals with the transforming process of the sunflower oil into PENTOLS. This consists in treating the sunflower oil with pentamaleinat in order to increase the number of the double bounds to the molecule of the triglyceride. Changing the stereo chemical structure of the molecule enables this oil to become drying, obtaining the characteristics of the linseed oil. Linseed oil is widely used in industry of the film forming substances making up to 25% at same paint recipes. Linseed oil is part of group of oils called drying oils a characteristic which gives it the priority in usage due to the great number of its double bonds. Recently there is a shortage of linseed oil in global scale. The sunflower treated with 7% pentamaleinat was used as a replacement of the polymerized linseed oil at the anticorrosive paints.

 

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JOZEFITA MARKU¹, KOZETA VASO²

Scientific paper [PDF]
UDC:620.196 :666.943.022

Optimization of copper slag waste content in blended cement production

Some industrial wastes such as blast furnace slag, fly ash, silica fume, by-product gypsum and nonferrous metal slag can be used as raw material and blending components in the cement industry. The amount of any waste used in this way depends on many factors such as the chemical and mineralogical composition of the waste itself and of the Portland cement, the size and shape of their particles, the amount of glassy phase in them, etc. Commonly, the proportions of Portland cement and its partial substitutes are developed by trial and error.
Based on theoretical considerations proposed by the field researchers, this study deals with the determination of the proportions of copper slag and Portland cement in the blended cement, having the objective of adding just enough of copper slag to consume all the excess calcium hydroxide produced during the hydration of the Portland cement. In terms of the cement chemistry ternary phase diagram, this means finding the intersection between the line connecting the cement composition and the slag composition and the boundary line of calcium hydroxide stability field.
A copper slag (waste of Lac, Albania Copper Plant) and Portland cement (produced in Fushe-Kruja,Albania Cement Factory) are used as specific constituents in the binary mixes of blended cement experimented in this work. In addition to the pozzolanic tests of mixes, with various content of copper slag determined according to ternary phase diagram, the mechanical strength tests of mortars produced with these binary mixes are carried out, too.
Key words: copper slag, partial constituent, ternary phase diagram, calcium hydroxide stability field

 

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Dr. LULJETA XHAGOLLI¹; Msc. ENTELA PINGULI²; ELIBJONDA GJERGJNDREAJ³

Scientific paper [PDF]
UDC:628.312.2 :663.48(496.5)

Minimization of waste waters discharges from albanian breweries

The objective of this paper is to provide information on identification of potential generated waste waters from Albanian breweries and to develop a strategy for minimization of their discharges. Pollution prevention waste water strategy consist on continuous examination of the operations at a facility with the goal of minimizing all types of waste waters.
Pollution prevention and control of waste waters is based on Best Management Practices (BMPs) which emphasize the source control of all waste waters generated at a facility through relatively inexpensive adjustments to process or operating procedures. This plan seeks to integrate environmental benefits and economic impact without any influence in product quality and industrial safety. Optimization of water consume through conservation and recycling is the best technique to fulfill this goal. The inefficient use of water as a raw material in a brewery can have environmental impacts. Therefore, minimization of waste water should not only include the improved management and control of water discharges, but also an optimization of process water input.

Key words: Waste water, discharge, water consume, Best Management Practices.

 

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KOZETA VASO, MEVLUDE DEMA

Scientific paper [PDF]
UDC:620.197.6:665.941.1

Preparation of the anticorrosive paints with long oil alkyd resins modified with maleic anhydride and phthalic anhydride

Long oil modified alkyd resins have a wide usage as film forming substances with protection characteristics at anticorrosive paints.
Alkyd resins have replaced the basic components of the anticorrosive paints, which formerly were produced through thermo-chemical processing of colophon products with polymerized vegetable oils. Until the year 2000 the colophon half products used in our country have been calcium rosinat, lead rosinat, esterified colophon with glycerin or pentaerythritol, phenol formaldehyde-modified resin with colophon etc.
In the present paper we report the usage of maleic anhydride as a partial replacement of phthalic anhydride in long oil modified alkyd resins. The usages of maleic anhydride as a partial replacement of phthalic anhydride at these resins as well as at the vegetable oils improve the characteristics of the film of paint, such as its hardness and its resistance against atmospheric and corrosive agents. Maleic anhydride influences also in the condensation time of alkyd resins. Usually, the maleic anhydride is added before the phthalic anhydride, because it links with the double bonds of the radicals of vegetable oils, raising the stereo chemical structure and helps to achieve, in a short time, the proper viscosity of the resin. Experiments have shown that the optimal quantity of maleic anhydride for achieving the desirable results is 2%.

 

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JELENA PJEŠ I!, DRAGAN RADONJI!, DARKO VUKSANOVI!, LJUBODRAG SAMARDŽI!

Originalni naučni rad [PDF]
UDC:620.197.4:669.715’5

Ispitivanje ponašanja protektorskih legura na bazi sistema Al-Zn u rastvorima hlorida razli itih koncentracija

Predmet istraživanja u ovom radu je bilo ispitivanje korozionih karakteristika legura na bazi sistema Al-Zn u sintetičkim vodenim rastvorima hlorida (0,51M; 0,051M i 0,0051M) na sobnoj temperaturi. Kompletna koroziona istraživanja račena su na savremenom sistemu za ubrzana istraživanja (potenciostat-galvanostat PAR model 273). Takođe, vršena su ispitivanja hemijskog sastava i mikrostrukture sintetisanih legura.
Eksperimentalnim istraživanjima, upotrebom navedenih metoda, određene su vrijednosti korozionog potencijala, polarizacionog otpora, gustine struje korozije i vrijednosti potencijala pri gustini struje koja je jednaka nuli, a snimljene su i potenciodinamičke krive protektorskih legura aluminijuma.

 

EXAMINATION OF BEHAVIOUR OF THE PROTECTORS ALLOYS BASED ON Al-Zn SYSTEM IN CHLORIDE SOLUTIONS OF DIFFERENT CONCENTRATION

The subject of this work was investigation of corrosion characteristics of aluminum alloys based on system Al-Zn in synthetic chloride solutions (0,51M; 0,051M and 0,0051M) at room temperature. Complete corrosion investigations were conducted on modern accelerated system for corrosion investigation (potentiostat-galvanostat PAR model 273). Also, we have examined chemical composition and microstructure of synthesized alloys.
Values of corrosion potential, polarization resistance, corrosion current density were determined using fore mentioned methods, and values of potential with current density equal to zero, and potentiodynamic curves of aluminum protector alloys were recorded.

 

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FEHIM KORA¹, SEAD ĆATIĆ², MERZUK CACAN3 SANJIN GUTI³, SAFIJA ISLAMOVI³

Originalni naučni rad [PDF]
UDC:620.93.4:615.461

Tačkasta korozija ortopedskog implantata u fiziološkim rastvorima

Tipični oblici korozionog napada na implantate su tačkasta, galvanska i treting korozija. Ljudsko tijelo je jedna veoma agresivna vodena i slana koroziona sredina.
Tačkasta korozija ortopedskog implantata na bazi nehrđajuđeg čelika u fiziološkim uslovima ispitivana je cikličnom voltametrijom. Korišteni su rastvori 0,9% NaCl i Hankov rastvor. Mjerenjem je utvrđeno da je implantat podložniji ta!kastoj koroziji u 0,9% rastvoru NaCl nego u Hankovom rastvoru. Za simuliranje efekata biomolekula koje prenose jone kroz organizam korišten je rastvor EDTA. LSV metodom je ispitivan uticaj kompleksirajkućih agenasa na stabilnost pasivnog sloja. Uočeno je da se dodatkom rastvora EDTA u koncentraciji već od 10 mmol/L dobije približno konstantna vrijednost potencijala oksidacije. Otpornost pasivnog sloja manja je u 0,9% rastvoru NaCl nego u Hankovom rastvoru. Dodatkom rastvora EDTA stabilizira se pasivni sloj, dobiju se veće vrijednosti korozionih potencijala.

Ključne riječi: ortopedski implantat, ta!kasta korozija, fiziološki rastvori

 

INVESTIGATION OF PITTING CORROSION ON ORTHOPEDIC IMPLANT IN PHYSIOLOGICAL SOLUTIONS

Typical forms of corrosive thrusts on implants are pitting, galvanic and treting corrosion. The human body is a very aggressive aquatic and salty medium. Pitting corrosion of the orthopedic implant made by stainless steel in physiological conditions are investigated by cyclic voltammetry method. In the mentioned investigation 0,9% NaCl and Hank’s solutions are used.  It was confirmed that sample tends to pitting corrosion in 0,9% NaCl solutions more than in Hank’s one. In order to simulate effects in which biomolecules transfers ions as a complex within human body solution of EDTA is used. By LSV method we explore influence of complex compounds on stability of passive layer. It was observed that addition of solution of EDTA exceeding concentration of 10 mmol/L leads to constant value of potential of oxidation.
We detect that resistance of the passive layer was less in 0,9% NaCl solution than in Hank’s solution. We can conclude that with addition of some amount of EDTA solution we can obtain stabilized passive layer and as consuqense one can observe a higher values of corrosive potential.

Key words: orthopedic implant, pitting corrosion, physiological solution

 

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M. M. BU KO¹, M. V. TOMIĆ², M. V. STOJANOVIĆ³ M. G. PAVLOVIĆ⁴, J. B. BAJAT¹

Originalni naučni rad [PDF]
UDC:620.197.5:669.38’74.058

Elektrohemijsko taloženje i koroziona stabilnost prevlaka Zn-Mn legura

Izučavan je uticaj vrste rastvora za taloženje na iskorišćenje struje prilikom elektrohemijskog taloženja Zn-Mn legura. Legure su taložene na čeliku iz hloridnog, sulfatnog i pirofosfatnog rastvora različitim gustinama struje. Ispitivan je uticaj gustine struje taloženja na izgled prevlaka legura, kao i njihovu korozionu stabilnost. Pokazano je da najveću korozionu stabilnost imaju legure dobijene taloženjem iz hloridnog rastvora gustinom struje od 2 A dm^-2.

Ključne reči: Elektrohemijsko taloženje legura, Zn-Mn legure, morfologija, koroziona svojstva

 

THE ELECTROCHEMICAL DEPOSITION AND CORROSION STABILITY OF Zn-Mn ALLOY COATINGS

The influence of the type of the deposition solution on the current efficiency during electrodeposition of Zn-Mn alloys was examined. The Zn-Mn alloys were deposited on steel from chloride, sulphate and pyrophosphate plating baths at different current densities. The influence of deposition current density on the appearance of alloy coatings, as well as their corrosion stability, was examined. It was shown that Zn-Mn alloys with the best corrosion properties, among all investigated in this work, were obtained from chloride plating bath at 2 A dm^-2.

Key words: Electrodeposition, Zn-Mn alloys, morphology, corrosion properties

 

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M. M. ANTONIJEVIC^* , M. B. RADOVANOVIC

Review paper [PDF]
UDC:620.193.6.7:669.38

Methods for Characterization of Protective Films on the Copper Surface – A Review

Formation of protective film on the copper surface and characterization of metal surface was the major subject of interest. In this paper was presented resolution in this field. Also, in paper was pay attention on methods which were used in investigation especially in the previous few years. According to the summarized results, described methods gave useful information about formation of protective film, which can block the dissolution of copper and its effectiveness, afterwards about strength of the bonds between atoms, corrosion inhibition mechanism, surface structure and adsorbed species on the metal surface. Inhibitors were mostly chemisorbed on the copper surface through different bond while presence of different group had influence on the inhibitor efficiency. Also, different types of bonds on the copper surface in the solution with different inhibitors were noticed.

Key words: corrosion inhibitors, EIS, XPS, FT-IR, SERS

 

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BROJ 3

 

A.S.FOUDA, G.Y.ELEWADY, M.G. SALAMA

Scientific paper [PDF]
UDC:620.173:669.75’782

Corrosion inhibition of aluminum-silicon alloy in H2SO4 solution using some thiophene derivatives

Inhibition of corrosion of Al-Si alloy by some thiophene derivatives in 0.5M H2SO4 was investigated by potentiodynamic polarization and electrochemical impedance spectroscopy (EIS) techniques. Polarization studies were carried out at different temperatures and showed that the investigated compounds are anodic inhibitors. The effect of temperature on corrosion inhibition has been studied and thermodynamic activation and adsorption parameters were calculated and discussed. Electrochemical impedance was used to investigate the mechanism of corrosion inhibition. The inhibition occurs through adsorption of the investigated compounds on the alloy surface without modifying the mechanism of corrosion process. The experimental data fit both of Temkin and kinetic-thermodynamic isotherm. A clear correlation was found between corrosion inhibition efficiency and theoretical parameters obtained by PM3 semiempirical method. The experimental results are supported by the theoretical data.

Keywords: Thiophene derivatives; corrosion inhibition; Al-Si alloy; H2SO4, quantum chemical calculations.

 

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A.LEEMA ROSE^a, FELICIA RAJAMMAL SELVA RANI^a A. PETER PASCAL REGIS b, SUSAI RAJENDRANc,d, A. KRISHNAVENI^e

Scientific paper [PDF]
UDC:620.197.3

Influence of biocides on corrosion inhibition efficiencies of mono sodium glutamate – Zn²⁺ system

The inhibition efficiencies and biocidal efficiencies of the biocides in the presence and absence of the mono sodium glutamate(MSG)- Zn²⁺ system in river(namely, Cauvery in Trichy, Tamilnadu, India) water and have been assessed. The inhibition efficiencies of MSG-Zn ²⁺system in the presence and absence of the biocides namely cetyl pyridinium chloride (CPC), benzyl trimethyl ammonium chloride (BTAC), and dodecyl benzene sulphonate (DBS) and the biocidal studies of biocides in the presence and absence of inhibitor system are studied. Among the three biocides, BTAC is found to be a very good inhibitor, which controls the corrosion of carbon steel in river (Cauvery) water. On comparing the biocidal efficiency of the biocides CPC is found to be the best among the three biocides which controls the growth of microbes in river water as well as a very good inhibitor which works in concurrence with the MSG-Zn²⁺ system in controlling the corrosion in river water.

Key words: Corrosion inhibition, carbon steel, river water, synergistic effect., biocide

 

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S. RAJENDRAN^1,2*, P. CHITRADEVI¹, S. JOHNMARY³,A. KRISHNAVENI⁴, S.KANCHANA⁵, LYDIA CHRISTY⁵, R. NAGALAKSHMI⁷, B. NARAYANASAMY⁸

Scientific paper [PDF]
UDC:620.197.3

Corrosion behaviour of SS 316 L in artificial saliva in presence of electral

Corrosion resistance of three metals namely, SS 316L, mild steel (MS) and mild steel coated with zinc (MS-Zn) has been evaluated in artificial saliva in the absence and presence of electral. Potentiodynamic polarization study and AC impedance spectra have been used to investigate the corrosion behaviour these metals. The order of corrosion resistance of metals in artificial saliva, in the absence and also in the presence of electral was SS 316L > MS > MS-Zn.

Keywords: Artificial saliva, corrosion, metals, electral, dentistry, oral hygiene

 

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JOZEFITA MARKU

Scientific paper [PDF]
UDC:666.972.16

The incorporation of fly ash as suplementary cementing material in concrete

Fly ash is a residue derived from the combustion of coal in furnaces of thermal power plant. The characteristics of fly ashes vary according to the combustion operation system as well as the coal composition. When fly ashes are used as partial replacement of Portland cement they alter the properties of the mortar or concrete. In this study, under scanning microscopic examination (SEM) as well as X-ray powder diffraction and other analyses, are investigated the characteristics of two fly ashes (imported by Fushe Kruja Cement Factory from Germany and Macedonia), such as the particles size and shape, the chemical and mineralogical composition and their content of glass and crystalline phase. In addition are investigated the effects of each fly ashes on fresh and hardened mortars properties, using Portland cement produced in Fushë-Kruja Cement Factory, in Albania. The investigated characteristics of ashes are confronted with tested properties of concretes produced with them and it is concluded that the better quality of the concrete produced by adding the ash from Germany is due to the composition and the content of glassy phase as well as the spherical form of particles in that fly ash.

Keywords: fly ash, Portland cement, microscopic examination, glass and crystalline phase, etc.

 

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ENTELA PINGULI¹, LULJETA XHAGOLLI² 

Scientific paper [PDF]
UDC:628.316.7

Alginate treatement of yeast slurry discharges a simple and eco-friendly method in minimisation of organic pollution of brewery waste waters

The brewing process requires a significant amount of water and produces wastewater with high biochemical oxygen demand and suspended solid content. Brewery wastes are extremely variable due to variation in production activity by season, by day of the week and by the time of day.
Organic and inorganic adsorbents are used in treatment of water and industrial effluents. Polymeric flocculants, natural as well as synthetic, because of their natural inertness to pH changes, low dosage requirements, and ease of handling, have become popular in water and wastewater treatment. In this paper alginates have been used in water purification and yeast immobilization. The main advantages are related with faster processing, lower content of insoluble solids, and a much smaller sludge volume. Alginates are a useful option since they have no adverse impact on human or environmental health.

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DUŠAN D. STANOJEVIĆ¹, MILOŠ B. RAJKOVIĆ², DRAGAN V. TOŠKOVIĆ¹, MIRJANA ANTONIJEVIĆ-NIKOLIĆ³

Originalni naučni rad [PDF]
UDC:669.536.1

Industrijska prerada mesingane šljake u hidrometalurgiji cinka

U radu su predstavljeni rezultati ispitivanja mogućnosti recikliranja cinka iz industrijske otpadne šljake koja nastaje u proizvodnji mesinga. Ovaj sekundar sadrži oko 50% cinka, 10% bakra i manje količine gvožđa, olova, kadmijuma i hlorida, a cilj istraživanja je bio da se ispita mogućnosat efikasne reciklaže cinka u okviru postojećeg industrijskog hidrometalurškog procesa proizvodnje cinka, u fabrici u Šapcu. Prethodnim laboratorijskim istraživanjem valorizacije šljake luženjem u otpadnom elektrolitu (sumporno-kiselom rastvoru iz hidrometalurške proizvodnje cinka) dokazano je da se dostiže izluživanje cinka od oko 95% i bakra oko 47%. Dobijeni rastvor ima pogodan sastav pa se može direktno uključiti u postojeći hidrometalurški proces proizvodnje cinka. Industrijskim eksperimentom luženja mesingane šljake povrđeni su ostvareni laboratorijski rezultati, a na bazi materijalnog bilansa zasnovanom na industrijskom eksperimentu dokazana je visoka efikasnost i ekonomska opravdanost ovakvog postupka.

Ključne reči: cink, bakar, mesingana šljaka, industrijska hidrometalurška valorizacija

 

INDUSTRIAL TREATMENT OF BRASS SLAG IN ZINC HYDROMETALLURGY

This paper presents the results of investigating the possibilities of zinc recycling out of industrial waste slag, which is formed during the brass production. This secondary contains approximately 50% of zinc, 10% of copper and less amounts of iron, lead, cadmium and chloride, with the aim to examine the possibility of efficient zinc recycling as a part of existing industrial hydrometallurgical process of zinc production, in the plant in Šabac. Previous laboratory investigations of slag valorization by leaching in waste electrolyte (sulphur-acid solution from hydrometallurgical zinc production) proved that leaching efficiency of, approximately, 95% of zinc and 47% of copper, could be reached. The obtained solution has a suitable content so it can be directly included in the already existing hydrometallurgical process of zinc production, with bigger control of chloride content. By industrial experiment of leaching brass slag, laboratory results were confirmed, and on the basis of materials balance established in industrial experiment, high efficiency and economic justification of this treatment was proved.

Key words: zinc, copper, brass slag, industrial hydrometallurgical valorization

 

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VLASTIMIR RADONJANIN¹, MIRJANA MALEŠEV¹,SNEŽANA MARINKOVIĆ²

Originalni naučni rad [PDF]
UDC:669.972.16

Mogućnosti primene starog betona kao nove vrste agregata u savremenom građevinarstvu

Karakteristika dvadesetog veka, sa aspekta građevinarstva, je intenzivna gradnja, pri čemu se nije dovoljno vodilo računa o očuvanju prirodnih resursa i o uticajima objekata na životnu sredinu u svim fazama eksploatacionog veka, zaključno sa rušenjem objekata i deponovanjem građevinskog otpada. Zbog toga je krajem dvadesetog veka otpad postao jedan od najvećih ekoloških problema u većini zemalja sveta. Kao održivo rešenje za probleme građevinskog otpada i iscrpljivanje nalazišta prirodnog agregata, prihvaćen je postupak recikliranja, u prvom redu “starog” betona. U prvom delu radu prikazani su tehnološki postupci za dobijanje recikliranog agregata od otpadnog betona, osnovna svojstva agregata dobijenog usitnjavanjem “starog” betona i svojstva betona na bazi recikliranog agregata. U drugom delu rada ukratko su prikazani rezultati sopstvenih komparativnih ispitivanja svojstava obi čnih i samougrađujućih betona sa prirodnim i sa recikliranim krupnim agregatom. Zaključeno je da se korišćenjem kvalitetnog čistog recikliranog agregata mogu dobiti betoni koji imaju zadovoljavajuće performanse koje se bitnije ne razlikuju od performansi betona sa prirodnim agregatom.

 

 

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BROJ 4

 

NEBOJŠA D. NIKOLIĆ

Review paper [PDF]
UDC:620197.5

Fundamental aspects of copper electrodeposition in the hydrogen co-deposition range

This a review paper considering fundamental aspects of copper electrodeposition at high overpotentials where parallel to copper electrodeposition, hydrogen evolution reaction occurs. The two types of copper deposits are formed in the hydrogen co-deposition range: (a) the open and porous structures denoted as the honeycomb-like ones, and (b) powdered deposits. Phenomenology of the formation of the honeycomb-like structure, as well as factors affecting the formation of this type of structure are described in detail. The increase of the specific surface area of the honeycomb-like structure by the application of the periodically changing regimes of electrolysis, such as pulsating overpotential (PO) regime is considered. Correlation between the shape of copper powder particles and the quantity of evolved hydrogen by which they are formed was also presented.

 

REZIME

 

Ovo je pregledni rad koji razmatra fundamentalne aspekte elektrohemijskog taloženja bakra na visokim prenapetostima gde paralelno procesu elektrohemijskog taloženja bakra se odigrava reakcija izdvajanja vodonika. Dva tipa taloga bakra su formirana u oblasti ko- depozicije vodonika: (a) otvorene i porozne strukture ozna čene kao strukture pčelinjeg saća, i (b) praškasti talozi. Fenomenologija formiranja strukture pčelinjeg saća, kao i faktori koji utiču na formiranje ovog tipa strukture su detaljno opisani. Povećanje specifične površine strukture pčelinjeg saća primenom periodično promenljivih režima elektrolize, kao što je režim pulsirajuće prenapetosti (PP), je razmatran. Uzajamna veza između oblika čestica praha i količine vodonika izdvojene tokom njihovog formiranja je takođe predstavljena.

 

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A. S. FOUDA, G. Y. ELEWADY, A. EL-ASKALANY, K. SHALABI

Scientific paper [PDF]
UDC:620.197.3:669.717

Inhibition of aluminum corrosion in hydrochloric acid media by three Schiff base compounds

 

The corrosion behavior of aluminum in 0.5 M HCl solution in the absence and presence of (E)-3,6-dibromo-2-((4-methoxyphenylimino)methyl)phenol(I),(E)-3,6-dibromo-2-((4-chlorophenylimino) methyl) phenol (II) and (E)-4-(3,6-dibromo-2-hydroxybenzylideneamino)benzoic acid(III)was investigated using potentio-dynamic polarization, electrochemical impedance spectroscopy (EIS) and electrochemical frequency modulation (EFM) techniques. The inhibitive action of the investigated compounds was discussed in terms of blocking the electrode surface by adsorption of the molecules through the active centers contained in their structures. The adsorption of these derivatives on aluminum surface is consistent with Freundlich adsorption isotherm. The effect of temperature on the rate of corrosion in the absence and presence of these compounds were also studied. Physical adsorption mechanism is proposed from the calculated thermodynamic parameters for all investigated compounds. Quantum chemical parameters such as the highest occupied molecular orbital energy (E_HOMO), the lowest unoccupied molecular orbital energy (E_LUMO), energy gap ( E), dipole moment (µ), electronegativity (χ), chemical potential (P_i), global hardness ( ) and softness (σ), were calculated. Quantum chemical studies indicate that the inhibition potentials of these compounds correlate well with E_HOMO, E, , σ, P_i, χand N. A good correlation was found between the theoretical data and the experimental results.

Key words: Aluminum, corrosion, HCl, quantum chemical calculation, PM3, Schiff bases.

 

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A.LEEMA ROSE¹, A. PETER PASCAL REGIS ², SUSAI RAJENDRAN^3,4, FELICIA RAJAMMAL, SELVA RANI¹, A KRISHNAVENI⁵

Scientific paper [PDF]
UDC:620.197.3:664.14

Synergistic effect of Fructose and Zn²⁺ in controlling corrosion of carbon steel

The inhibition efficiency of fructose (FR)-Zn²⁺ system in controlling corrosion of carbon steel in an aqueous environment has been evaluated by mass- loss method. The synergistic effect is noticed between fructose and Zn²⁺.The formulation consisting of 125 ppm of fructose and 50 ppm of Zn ²⁺shows 84% inhibition efficiency(IE).At lower and higher pH value IE decreases. Polarisation study reveals that FR-Zn²⁺ system functions as a mixed inhibitor. AC impedance spectra reveal that a protective film is formed on the metal surface.FTIR spectra, UV absorbtion spectra and SEM studies have been used to investigate into the nature of the thin protective film formed on the metal surface.A suitable mechanism of corrosion inhibition is proposed based on the results obtained from mass loss study and surface analysis technique.

Key words: Corrosion inhibition, carbon steel, river water, synergistic effect

 

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B. SHYAMALA DEVI¹, S. JOHN MARY², S. RAJENDRAN^3*, N. MANIMARAN⁴, P. RENGAN⁴,J.JAYASUNDARI⁵, M. MANNIVANNAN⁶

Scientific paper [PDF]
UDC:504.45.058:546.49

Removal of mercury by biosorption onto sphaeroplea algae

To curtail mercury pollution problem, adsorbent based on Sphaeroplea algal biomass were tried for the removal of mercury ion from aqueous solution. Dried and powdered biomass were activated with acid (1N HNO₃), alkali (1N NaOH) and washed thoroughly and dried in oven. The effect of initial concentration, pH and contact time was studied in batch experiments. The percentage removal of mercury decreased with increase in initial concentration, due to the limited number of available active sites on the surface of natural and acid treated algae to accommodate higher concentration of mercury ions. The effect of the pH indicated that the percentage removal increases with decrease in pH. At pH 7 the maximum removal of 60% of mercury is achieved in natural and 85% in acid treated algae. The percentage removal of mercury increases with increase in contact time and availability of active sites. The maximum removal of mercury at pH 7 shows that 240 mts is sufficient to remove above 85% of mercury

Keywords: Removal of mercury, Sphaeroplea algae, biosorption, water pollution, heavy metals

 

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J. WILSON SAHAYARAJ¹, SUSAI RAJENDRAN^2*, T.S. MUTHU MEGALA², A. JOHN AMALRAJ³

Scientific paper [PDF]
UDC:620.197.3:669.14

 

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DRAGAN UGRINOV¹, ALEKSANDER STOJANOV²

Stručni rad [PDF]
UDC:504.53.062.4:633.453

Bioremedijacija u tretmanu zagađenog zemljišta

Ovaj rad opisuje primenu bioremedijacije, uslove za njeno odvijanje kao i ograničavajuće fakto-re.Bioremedijacija je u suštini proces koji predstavlja sposobnost mikroorganizama da razlažu različite opasne materije, i ima rastuću ključnu ulogu u prečišćavanju zagađenog zemljišta i podzemnih voda. Ovi procesi dobijaju svoje mesto zahvaljujući kapacitetu enzimskog metabolizma mikroorganizama da transformišu organske zagađivače u polutante i manje opasna jedinjenja. Ali,ne treba zaboraviti da ovu metodu nije moguće primeniti u svakom slu čaju. Među raspoloživim opcijama za prečišćavanje zagađenog zemljišta, bioremedijacija je najbolja zato što najmanje remeti životnu sredinu i sa ekonomske tačke gledišta-manje košta.

Ključne reči: zemljište, zagađenje, bioremedijacija, mikroorganizmi

 

INFLUENCE THE CYCLES OF CONCENTRATION ON OPERATION OF COOLING SYSTEM