Zaštita materijala 3. 2017

 

 

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Tilia leafs as eco-friendly corrosion inhibitor for mild steel in aqueous solutions

Abstract

Tilia Leafs extract activity as a green corrosion inhibitor (environmental friendly) for mild steel in 1M HCl has been tested using weight loss, potentiodynamic polarization, electrochemical impedance spectroscopy (EIS). The obtained results show that Tilia Leafs extract is an excellent corrosion inhibitor. The inhibition efficiency increases with increasing the temperature from 25 to 45^oC, reaching a maximum value of 79 % at the highest concentration of 300 ppm at the temperature of 45^oC. Polarization measurements demonstrate that the Tilia Leafs extract acts as a mixed type inhibitor. Nyquist plot illustrates that on increasing Tilia Leafs extract concentration, the charge transfer increases and the double layer capacitance decreases. The adsorption of Tilia Leafs extract on mild steel obeys Temkin adsorption isotherm.

Keywords: Mild steel, HCl, Corrosion inhibition, Tilia Leafs extract, EIS.

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TILIA LEAFS KAO EKOLOŠKI INHIBITOR KOROZIJE ZA MEKI  ČELIK U VODENIM RASTVORIMA

Izvod

Aktivnost ekstrakcije Tilia Leafa kao zelenog inhibitora korozije (ekološki prihvatljiv) za meki čelik u 1M HCl testirana je korišćenjem gubitka težine, potentiodinamičke polarizacije i elektrohemijske impedansne spektroskopije (EIS). Dobijeni rezultati pokazuju da je Tilia Leafs ekstrakt odličan inhibitor korozije. Efikasnost inhibicije povećava se s povećanjem temperature od 25⁰C do 45⁰C, dostižući maksimalnu vrednost od 79% pri najvećoj koncentraciji inhibitora od 300 ppm na temperaturi od 45⁰C. Merenja polarizacije pokazuju da ekstrakt Tilia Leafs deluje kao inhibitor mešovitog tipa. Nikuist-a kriva ilustruje da pri povećanju koncentracije ekstrakta Tilia Leafs prenos naelektrisanja raste i smanjuje se kapacitivnost dvostrukog sloja. Adsorpcija ekstrakta Tilia Leafs na mekom čeliku ponaša se po Temkinovoj izotermi adsorpcije.

Ključne reči: meki čelik, HCl, inhibitori korozije, Tilia Leafs ekstrakt, EIS.

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Uticaj obrade enzimima na antimikrobna svojstva pletenina bojenih ekstraktima lekovitih biljaka

Izvod

U ovom radu je istraživan uticaj upotrebe različitih vrsta predtretmana (vodonik-peroksidom i enzimima) na antimikrobna svojstva pletenina bojenih alkoholnim ekstraktom biljke Achillea millefolium L. Za istraživanja su korištene tri pamučne pletenine različitih konstrukcijskih karakteristika i površinskih masa. Bojenje pletenina metanolskim ekstraktom biljke Achillea millefolium konc. 25 mg/mL rađeno je koristeći metodu iscrpljenja kupatila uz naknadnu obradu alginatom. Antimikrobno dejstvo pletenina obrađenih ekstraktima biljke Achillea millefolium L. na bakterije Staphylococcus aureus i Escherichia coli određivano je metodom paralelnih linija (AATCC TM 147).

Pored ispitivanja antimikrobnih svojstava određivan je gubitak mase predtretiranih pletenina, sposobnost zadržavanja vode i razlika boje predtretiranih i bojenih pletenina, a sve u zavisnosti od vrste primijenjene predobrade pletenina.

Ustanovljeno je da pletenine, nakon bojenja metanolskim ekstraktom biljke Achillea millefolium  konc. 25 mg/mL uz naknadnu obradu alginatom, koje su prethodno tretirane enzimima pokazuju bolje antimikrobno dejstvo na bakteriju Escherichia coli u odnosu na pletenine tretirane H₂O₂.

Ključne riječi: bojenje, enzimi, ekstrakti biljaka, antimikrobna svojstva.

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THE INFLUNCE OF ENZYMATIC TREATMENT ON ANTIMICROBIAL PROPERTIES OF KNITTED FABRICS DYED WITH PLANT EXTRACTS

Abstract

In this paper the influence of different types of pretreatment (hydrogen peroxide and enzymes) on antimicrobial properties of knitted fabrics dyed with plant extracts of Achillea millefolium L. was examined. Three different cotton fabrics with different constructional characteristics and surface masses were used.

Knitted fabrics were treated with methanolic plant extract (concentration 25 mg/mL) by using bath exhaustion method and subsequently treated with alginate. Antimicrobial properties of knitted fabrics treated with plant extract of Achillea millefolium L. on Escherichia coli, Staphylococcus aureus by using parallel streaking method (AATCC TM 147) were tested.

In addition to antimicrobial properties testing, the mass loss of pretreated knitted fabrics, water retention value and color difference of pretreated and dyed knitted fabrics were also tested, depending on the type of applied pretreatment of knitted fabrics.

It was found that the enzymatically treated knitted fabrics dyed with methanolic extract of the plant Achillea millefolium L. (concentration 25 mg/mL) and subsequently treated with alginate had better antimicrobial activity against Escherichia coli, compared to knitted fabrics treated with H₂O₂.

Keywords: dyeing, enzymes, plant extracts, antimicrobial properties.

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Uticaj viskoznosti dispergovane faze na koalescentnu filtraciju

Izvod

Zauljene vode neminovan su pratilac u svim granama procesne industrije:  preradi nafte, proizvodnji nafte, petrohemijskih, farmaceustkih i drugih hemijskih proizvoda, u prehrambenoj, kao i u metaloprerađivačkoj industriji, servisima za održavanje vozila i na brodovima. Zbog široke primene koalescera za tretman zauljenih voda i složenosti fenomena, projektovanju odgovarajućih koalescentnih filtera specifičnih karakteristika predhode opsežna poluindustrijska istraživanja. U različitim granama procesne industrije, potrebno je izvršiti separaciju dispergovane uljne faze različite prirode, pri čemu je viskoznost jedna od bitnih osobina koja utiče na separaciju. Pored toga geometrija sloja može da promeni uticaj viskoznosti. Cilj ovog rada je da ispita uticaj viskoznosti dispergovane uljne faze primenom sloja vlakana dva otpadna polimera različite permeabilnosti na efikasnost koalescentne filtracije. U ovom radu dati su rezultati ispitivanja tri različite model emulzije dobijene dispergovanjem uljne faze: domaća nafta A, njena frakcija A4 i namešani poluproizvod P1 u vodi za piće. Eksperimenti su vršeni u opsegu peremabilnosti sloja od 0,18·10^-9  do 5,389·10^-9  m². Koriščeni su otpadni polietilenteraftalat BA1 i otpadni polipropilen, PP. Opseg brzina u ogledu bio je od 19 do 70 m/h. U slučaju kada viskoznost disperzne faze varira od 10 do 168 mPa s, filtarsko punjenje u koalesceru treba da bude od materijala BA1, a permeabilnost sloja niska. Dok je punjenje PP pogodno za korišćenje u slučaju viših viskoznosti disprezne faze preko 80mPa s kada je neophodno da sloj bude visoke permeabilnosti jer se u tim okolnostima postiže veća radna brzina. Cilj je naći uslove u kojima se realizuje veća radna brzina pošto se time smanjuje dimenzija uređaja.

Ključne riječi: koalescentna filtracija, zauljene vode, viskoznost uljne faze, naftno polje.

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THE EFFECT OF VISCOSITY OF DISPERSED PHASE ON COALESCENT FILTRATION

Abstract

Oily water is formed in: oil production and refining, petrochemical, pharmaceutical, chemical and food production, metal processing as well as in services for vehicles and ship maintenance. Due to the wide application of coalescence filtration for the treatment of different kind of oily water and complexity of the phenomenon, the design of appropriate coalescer with specific characteristics precede extensive semi-industrial research. In process industry, it is necessary to separate the dispersed oil phase of different nature, and the viscosity is one of the important characteristics affecting the separation. The aim of this study is to investigate the viscosity influence of the dispersed oil phase on the coalescence filtration efficiency using two waste polymer fiber beds over different bed permeabilities. Three different model emulsions obtained by dispersing the oil phase: domestic oil – A, fractions of domestic oil – A4, mixed intermediate product – P1 in drinking water were investigated. Experiments were carried out for bed permeability range from 0.18∙10^-9 to 5.389∙10^-9 m². Waste polyethylene terephthalate – BA1 and waste polypropylene – PP were used. The velocity was kept in the range from 19 to 70 m/h. In the case where the viscosity of the dispersed phase ranges from 10 to 168 mPa s, the bed filter in the coalescer should be BA1 material with low bed permeability. While in the case of higher viscosity, above 80mPa s, the bed filter in the coalescer should be PP material with high bed permeability because in these circumstances greater operating velocity of 55 m/h is achieved resulting in the reduction of the coalescer dimensions.

Keywords: coalescence filtration, oily water, viscosity of the oily phase, oil field.

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Uticaj jačine struje zavarivanja na otpornost prema piting koroziji zavarenog spoja nerđajućeg čelika X5CrNi18-10

Izvod

Ispitan je uticaj jačine struje zavarivanja na otpornost prema piting koroziji zavarenog spoja austenitnog nerđajućeg čelika X5CrNi18-10. Zavarivanje  austenitnog nerđajućeg čelika je izvršeno primenom tri različite jačine struje (110 A, 130 A i 150 A). Ispitivanja otpornosti prema piting koroziji su izvršena elektrohemijskom potenciodinamičkom metodom na osnovnom metalu, u zoni uticaja toplote (ZUT) i u metalu šava zavarenog spoja. Vrednosti pokazatelja piting korozije za osnovni metal su bliske vrednostima odgovarajućih pokazatelja za metal šava, nezavisno od primenjene jačine struje pri zavarivanju. Vrednosti pokazatelja piting korozije u ZUT-u su manje od vrednosti odgovarajućih pokazatelja za osnovni metal i metal šava. To je posledica delimičnog izdvajanja hrom-karbida po granicama zrna i obrazovanja hromom osiromašenih oblasti uz granicu zrna u ZUT-u. ZUT formiran pri jačini struje zavarivanja od 150 A pokazuje najmanju otpornost prema piting koroziji, što se može objasniti najvećim osiromašenjem prigraničnih oblasti zrna hromom pri ovoj jačini struje zavarivanja. Tada je i sklonost ZUT-a prema interkristalnoj koroziji najveća. Povećanjem stepena senzibilizacije ZUT-a prema interkristalnoj koroziji vrednost potencijala metastabilnog pitinga se linearno smanjuje, što znači da se smanjuje otpornost ZUT-a prema piting koroziji.

Ključne reči: nerđajući čelici, zavareni spoj, piting korozija, metode ispitivanja.

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INFLUENCE OF WELDING CURRENT INTENSITY ON PITTING CORROSION RESISTANCE IN WELDED JOINT OF STAINLESS STEEL X5CrNi18-10

Abstract

The effect of welding current on the pitting corrosion resistance in the welded joint of austenitic stainless steel X5CrNi18-10 was tested. Welding was carried out using three different current intensity (110 A, 130 A and 150 A). Testing of pitting corrosion resistance was performed by electrochemical potentiodynamic method on the base metal, in the heat affected zone (HAZ) and in the weld metal. Values of pitting corrosion resistance indicators for the base metal are similar to values of the indicators for the weld metal, regardless of the applied welding current. The values of indicators for pitting corrosion resistance in the HAZ are less than the values of these indicators for the base metal and for the weld metal. This is caused by the precipitation of chromium carbides at grain boundaries and by partial formation of chromium depleted areas along the grain boundaries in the HAZ. HAZ that was formed at welding current of 150 A shows the smallest pitting corrosion resistance. This can be explained by the largest depletion in chromium of grain boundary areas at welding current of 150 A. The sensitization degree in the HAZ to intergranular corrosion is also the greatest, in this case. With increase of the sensitization degree to intergranular corrosion the value of metastable pitting potential linearly decreases, which means that pitting corrosion resistance in the HAZ is reduced.

Keywords: stainless steels, welded joint, pitting corrosion, test methods.

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Pyrolysis and gasification in the process of sewage sludge treatment

Abstract

Pyrolysis and gasification represent a thermo-chemical process of solid mass conversion and the products obtained are: liquidity (pyrolytic oil), gases and coke residue. In modern society, there is a growing need for the use of ecological systems and renewable energy sources. As a potential and renewable energy resource we can consider sewage sludge. Sewage sludge is mostly disposed of in nature, while a very small part of the treats. Due to the non-adequate treatment of sewage sludge there is a high risk of impacts of harmful substances on humans and animals. Apart from the fact that the sewage sludge can be a major energy potential, thermal treatment allows to solve the problem of disposal of sewage sludge in nature and environmental pollution. Utilizing the sewage sludge as an energy source would generate large fossil fuels, neutralize sewage sludge landfills and reduce the risk of developing and spreading the disease due to the presence of harmful substances.

Keywords: gasification, sewage sludge, pyrolysis, thermal processes.

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PIROLIZA I GASIFIKACIJA U PROCESU TRETMANA KANALIZACIONOG MULJA

Izvod

Piroliza i gasifikacija predstavljaju termohemijski proces konverzije čvrste mase, a dobijeni proizvodi su: tečnost (pirolitičko ulje), gasovi i koks kao čvrsti ostatak. U modernom društvu se sve više javlja potreba za primenom ekoloških sistema i obnovljivih izvora energije. Kao potencijalni i obnovljivi energetski resurs možemo smatrati kanalizacioni mulj. Kanalizacioni mulj se pretežno odlaže u prirodu, dok se veoma mali deo tretira. Zbog neadekvatnog tretmana kanalizacionog mulja postoji veliki rizik od uticaja štetnih materija na čoveka i životinje. Osim što kanalizacioni mulj može predstavljati veliki energetski potencijal, termički tretman omogućava da se reši problem odlaganja kanalizacionog mulja u prirodu i zagađenje životne sredine. Iskorišćenjem kanalizacionog mulja kao energenta ostvarile bi se velike uštede fosilnog goriva, neutralisala bi se odlagališta kanalizacionog mulja i smanjio bi se rizik od nastanka i širenja bolesti usled prisustva štetnih materija.

Ključne riječi: gasifikacija, kanalizacioni mulj, piroliza, termički procesi.

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Antimikrobno dejstvo aktivnog ugljeničnog materijala dobijenog hidrotermalnom karbonizacijom fruktoze

Izvod

Aktivni ugljenik ima jedinstvena hemijska i fizička svojstva, što je veliki potencijal za antimikrobnu aktivnost ovih materijala. Aktivni ugljenični materijal je dobijen na temperaturi od 260 ^oC, hidrotermalnom karbonizacijom fruktoze u prisustvu fosforne kiseline. Rezultujući ugljenični materijal karakterisan je pomoću: merenja izotermi adsorpcije/desorpcije tečnog azota, skanirajućom elektronskom mikroskopijom i Fourier-ovom transformacijskom infracrvenom spektroskopijom. Dobijeni materijal se ispitivao kao antimikrobni agens primenom LB agar testa na mikrobe kože. Dobijeni aktivni ugljenični materijal ima specifičnu površinu od 932 m²/g. Poseduje kiseonične funkcionalne grupe na površini materijala i pokazao se kao jako dobar antimikrobni agens. Koncentracija aktivnog ugljeničnog materijala značajno utiče na antimikrobne efekte.

Ključne reči: hidrotermalna karbonizacija, fruktoza, aktivni ugljen, antimikrobni efekat.

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ANTIMICROBIAL EFFECT OF ACTIVE CARBONACEOUS MATERIAL OBTAINED BY HYDROTHERMAL CARBONIZATION OF FRUCTOSE

Abstract

Activated carbons due to their antimicrobial effect have been used in medicine for a long period of time. The active carbon material is obtained at a temperature of 260 ° C, by hydrothermal carbonization of fructose in the presence of phosphoric acid. The resulting carbonaceous materials were characterized by: nitrogen adsorption/desorption isotherms measurements, by scanning electron microscope and Fourier transform infrared spectroscopy. The resulting material was examined as an antimicrobial agent by using LB agar assay on skin microbes. The obtained active carbon material has a specific surface area of 932 m²/g. The presence of oxygen functional groups on the material surface was observed and material was proved to be a very good antimicrobial agent. The concentration of activated carbon strongly affects antimicrobial effects.

Keywords: hydrothermal carbonization, fructose, active carbon, antimicrobial effect.

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Efikasnost primene tehnike stabilizacije/solidifikacije na jalovinu iz Rudnika Bor

Izvod

Odlaganje jalovine koja nastaje prilikom prerarde rude iz rudnika Bor, predstavlja veoma veliki problem za životnu sredinu usled visokog stepena zagađenja jalovine teškim metalom, u ovom slučaju bakrom. Zbog toga je neophodno jalovinu podvrgnuti određenim tretmanima remedijacije. U ovom radu vršeno je ispitivanje procesa izluživanja bakra i efikasnost tretmana jalovine rudnika Bor koja je stabilizovana/solidifikovana primenom gline i letećeg pepela kao imobilizacionih agenasa. Urađena je karakterizacija jalovine pomoću semi-dinamičkog testa izluživanja u rezervoaru – ANS 16.1. Svi imobilizacioni agensi u tretmanu jalovine su se pokazali dosta uspešno.Tretirani otpad se može smatrati prihvatljivim za odlaganje, a može se razmotriti i njegova „kontrolisana upotreba“.

Ključne reči: jalovina, bakar, solidifikacija/stabilizacija, glina, leteći pepeo.

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EFFICIENCY OF APPLICATION THE SOLIDIFICATION/STABILIZATION TECHNIQUE ON MINE TAILINGS FROM THE BOR

Abstract

Disposal of mine tailings which appears during the mining activity from Bor mine, represents enormously large environmental problem, because mine tailings is highly polluted by heavy metal, in this case by copper. Therefore it is necessary to expose mine tallings to certain treatments of remediation. In this work main object of the study was to show the leaching of metals and treatment efficiency of mine tailings from Bor that was stabilized/solidified by applying clay and fly ash as an immobilization agents. Characterization was preformed using semi-dynamic leaching test ANS 16.1. All immobilization agents in the treatment of copper were quite successful in the stabilization/solidification of mine tailings. Treated waste can be considered acceptable for disposal, and even considered for “controlled utilization”.

Keywords: mine tailing, copper, clay, stabilization/solidification, fly ash

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Proučavanje lipofilnosti i toksičnosti derivata azo boja

Izvod

Azo boje imaju širok spektar primene u različitim granama industrije, a dospevanjem u vodene ekosisteme se mogu ponašati kao polutanti. Prvi korak u predviđanju eventualnih toksičnih efekata jedinjenja u životnoj sredini obuhvata procenu njegove lipofilnosti. Lipofilnost je za odab­rane derivate azo boja ispitivana primenom tankoslojne hromatografije na obrnutim fazama (RPTLC_18F254s) u t-butanolu i N,N-dimetilformamidu, kao i korišćenjem odgovarajućih softverskih paketa.

Primenom metodom linearne regresije je uspostavljena zavisnost između hromatografskih parametara (R_M⁰ i m) i vrednosti podeonog koeficijenta, log P kao standardnog merila lipofilnosti. Proučavana je i zavisnost između hromatografskih parametara (R_M⁰ i m) i softverski dobijenih vrednosti efektivne koncentracije, EC₅₀, kao merila akutne toksičnosti, ispitivanih derivata azo boja za različite test organizme. Dobijeni rezultati ukazuju da se hromatografski parametri, R_M⁰ i m, mogu pouzdano primenjivati za opisivanje lipofilnosti (procenu toksičnih efekata) proučavanih derivata azo boja.

Ključne reči: azo boje, lipofilnost, RPTLC, log P, toksičnost.

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EXAMINATION OF LIPOPHILICITY AND TOXICITY OF AZO DYES DERIVATIVES

Abstract

Azo dyes, in addition to showing a wide range of applications in various industries, after releasing into aquatic ecosystems can act as pollutants. The first step in the prediction of possible toxic effects of compounds in the environment includes the estimation of its lipophilicity. Lipophilicity of selected derivatives of azo dyes was examined by thin layer chromatography on a reversed phase (RPTLC18F254s) in t-butanol and N,N-dimethylformamide, as well as by applying appropriate software packages.

Relationship between lipophilicity chromatographic parameters (RM0 and m) and values of partition coefficient, log P, as standard measure of lipophilicity was established applying linear regression analysis. Also, relationship between chromatographic parameters (RM0 and m) and computational values of effective concentration, EC50, as a measure of acute toxicity of investigated derivatives for different test organisms was studied. Obtained results show that chromatographic parameters (RM0 and m) could be successfully used for describing lipophilicity (estimation of toxic effects) of examined derivatives of azo dyes.

Keywords: azo dyes, lipophilicity, RPTLC, log P, toxicity.

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Biodegradable polymers suitable for tissue engineering and drug delivery systems

Abstract

Biodegradable polymers for medical and pharmaceutical application have been in the focus of scientific interest in the last two decades. Among the others, features like biocompatibility, supportive cell proliferation and biodegradation are considered as crucial in the fabrication of scaffolds in tissue engineering and controlled drug delivery systems. Polymers based on polyesters, polyethers, polyan­hy­drides, poly(ether esters), poly(ortho esters), poly(amino acids) are very significant for the application in medicine and pharmaceutics. Porous polymer matrices in tissue engineering encourage the growth of cells, at the same time allowing the exchange of nutrients and residuals. Drug delivery systems, where biological agent is dispersed / dissolved in the polymer matrix, act as reservoirs, while drug carriers are those systems where the active substance and matrix are chemically bonded. Of particular interest to many researchers are the systems in which degradation profile of polymer matrix is crucial in the determination of the rate by which the medicament is released. Biodegradable nanosized systems as devices of controlled release or selected targeting of active component attract significant attention.

This paper provides a brief outline of biodegradable polymers, the properties important for their application in medicine, with particular interest in their hydrolytic degradation, and at the same time, it will serve as a basis for further research in this area.

Keywords: biodegradable polymers, tissue engineering, drug delivery systems.

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BIORAZGRADLJIVI POLIMERI POGODNI ZA INŽENJERSTVO TKIVA I SISTEMA ZA DOSTAVU LEKOVA

Izvod

Biorazgradivi polimeri za medicinsku i farmaceutsku primenu su u fokusu naučnog interesovanja u poslednje dve decenije. Između ostalih karakteristika, osobine poput biokompatibilnosti, podržavanje proliferacije ćelija i biorazgradljivost smatraju se kao ključne u izradu podloga u inženjerstvu tkiva i sistema za kontroliranu dostavu lekova. Polimeri na bazi poliestera, polietera, polianhidrida, poli(etar estera), poli(orto estera), poli(amino kiselina) su veoma značajni za primenu u medicini i farmaciji. Porozne polimerne matrice u inženjeringu tkiva podstiču rast ćelija, omogućavajući istovremenu razmenu nutrijenata i metabolita. Sistemi za dostavu lekarstava, gde je aktivna komponenta dispergovana / rastvorena u polimernoj matrici, imaju ulogu rezervoara, dok nosioci lekova su sistemi u kojima je aktivna supstanca vezana hemijski za polimernu matricu. Poseban interes mnogih istraživača privlače sistemi u kojima degradacija polimernih matrica je krucijalna u određivanju brzine kojom se lek oslobađa. Biorazgradljivi sistemi sa nanodimen­zijama, koji imaju ulogu uređaja za kontolirano oslobođenje ili selektivno nasočivanje aktivne komponente privlače značajnu pažnju.

Ovaj rad predstavlja kratki pregled biorazgradljivh polimera, njihova svojstva značajna za primenu u medicini, sa posebnim naglaskom na njihovu hidrolitičku degradaciju, što bi poslužilo kako osnova za dalja istraživanja u ovom području.

Ključne reči: biorazgradljivi polimeri, inženjering tkiva, sistemi za dostavu lekova.

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Azotne jonske grupe i jedinjenja prisutna u vodi za piće na teritoriji Severno-bačkog okruga

IZVOD

Rezultati ispitivanja vode za piće u pogledu prisustva azotnih jonskih grupa i jedinjenja na teritoriji Severno-bačkog upravnog okruga u periodu 2013-2015. godine u malom procentu beleže odstupanja od dozvoljenih vrednosti.

Na teritoriji Grada Subotice dokazana je statistička značajnost u pogledu prisustva amonijaka u uzorcima vode. Najmanji procenat neispravnosti karakteriše 2014, a najveći 2015. godina. Za seoski vodovod na teritoriji Grada Subotice karakteristične su manje razlike posmatrano po godinama, koje nemaju statističku značajnost, ali je situacija znatno lošija u odnosu na gradski vodovod (više od 40% uzoraka). Ovako visok procenat neispravnosti može se objasniti postojanjem većeg broja sela bez mogućnosti organizovanog vodosnabdevanja stanovništva, te korišćenjem vode iz nedovoljno kontrolisanih sopstvenih bunara.

Gradski vodovod Opštine Bačka Topola u pogledu neispravnosti uzoraka u smislu prisustva amonijaka je iznad dozvoljenih vrednosti, i karakteriše ga odstupanja i statistički značajna razlika. Za razliku od gradskog vodovoda bačko-topolske opštine gde je najmanje neispravnih uzoraka zabeleženo 2013. godine, za seoski vodovod najveći broj neispravnih uzoraka upravo je u 2013. godini, a najmanji u 2014. godini.

Teritoriju Opštine Mali Iđoš karakteriše veoma mali broj neispravnih uzoraka pijaće vode po pitanju prisustva amonijaka. Za sve tri posmatrane godine, nije bilo većih variranja u pogledu neispravnosti, te ni statistički značajne razlike po godinama.

Posmatrano po opštinama, uočena je statistički značajna razlika u broju neispravnih uzoraka za sve tri godine. Klimatska situacija i količina padavina u toku 2014. godine je, kao i na većoj teritoriji Republike Srbije, bila neuobičajena i na teritoriji Grada Subotica. Premašen je dugogodišnji prosek u količini padavina, što je rezultiralo najnižom koncentracijom amonijaka u gradskom vodovodu. Takođe, najmanji procenat prekoračenja graničnih vrednosti amonijaka u vodi za piće u Opštini Bačka Topola, u seoskom vodovodu, zabeležen je 2014. godine.

Ključne reči: voda za piće, Severno-bački okrug, nitrati, nitriti.

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NITROGENOUS IONIC GROUPS AND COMPOUNDS PRESENT IN DRINKING WATER ON THE TERRITORY OF NORTH-BAČKA DISTRICT

Abstract

In the territory of North-Bačka administrative district examination of drinking water regarding nitrogenous ionic groups and compounds during the period from 2013 to 2015 show was a slight deviation of comparing to the allowed ones.

Statistical significance for the presence of ammonia in water samples was proven in samples taken from water supply of Subotica city. The lowest percentage of faulty samples was found in a year 2014 and the largest in a year 2015. Rural water supply of the Subotica city is characterized by minor differences observed in a time, with no statistical significance. However, comparing with the city water supply, the situation is much worse (in more than 40% of samples). Such a high percentage of faulty samples can be explained with existence of a huge number of non-organized water supplies in villages, as well as because of the using water from an insufficiently controlled private wells.

Regarding the faulty samples, the water supply of the Bačka Topola municipality has the level of ammonia above the permitted, with deviations and statistically significant difference. Unlike the water supply of the Bačka Topola municipality, which has the lowest number of faulty samples recorded in 2013, in the rural water supply the number of faulty samples was the biggest in 2013 and the lowest in 2014.

The territory of Mali Idjos municipality is characterized with a very small number of a faulty samples of drinking water regarding the presence of ammonia. For all three analyzed years, there were no major variations regarding faulty samples and no statistically significant differences.

Observed by municipalities, there is a statistically significant difference in the number of faulty samples for all three years. Climate situation and the amount of rainfall during the 2014 was unusual in the Subotica city, as also at the larger territory of the Republic of Serbia. Long-term average in rainfall was exceeded, resulting with the lowest concentration of ammonia in the city water supply. Also, the lowest percentage of exceeding the limit value of ammonia in drinking water was recorded in 2014, in the rural water supply of the Bačka Topola municipality.

Keywords: drinking water, North-Bačka area, nitrate, nitrite

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The influence of molecular weights on the calcium salts absorption of polyacrylic based materials

Abstract

Most of the industries use water as medium for heating, cooling and also washing of the equipment and facing problems caused by hard water which consist of carbonate and sulfate salts which remain on the walls of reactors and pipes. For this reason, different water softeners are used, with ability to absorb metallic ions and prevent agglomeration of salts on surfaces. Polymeric materials, especially polycarboxylates, can be used to prevent this problem. In this work the influence of molecular weight and molecular composition of poly(acrylic acid–co–maleic acid) carboxylate copolymer on the calcium salts absorption was investigated. Copolymers were prepared by radical polymerization in water-borne system using potassium persulfate as initiator and iron ions (Fe²⁺) as chain length regulator. Molecular structures of obtained polymers were analyzed by FTIR method, and confirmed copolymer structure of resulted polymers. Average molecular weights and degree of polydispersity were determined by GPC. From the results of molecular weights determination it can be concluded that increasing of Fe²⁺ content leads to decreasing of the molecular weights of copolymers. Presence of ordered structures was confirmed using X-ray diffraction method (XRD). Dispersing capacity results of obtained copolymers have showed that with decreasing of molecular weights of copolymers calcium carbonate dispersing capacity (CCDC) decreased.

Keywords: poly(acrylic acid-co-maleic acid), metal ions absorption, polycarboxylates.

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UTICAJ MOLEKULSKE MASE POLIAKRILNIH MATERIJALA NA SVOJSTVA ABSORPCIJE KALCIJUMOVIH SOLI 

Izvod

Većina industrijskih postrojenja koristi vodu kao medijum za grejanje, hlađenje i pranje opreme i suočava se sa problemima izazvanim tvrdom vodom koja sadrži karbonatne i sulfatne soli koje zaostaju na zidovima reaktora i cevi. Iz ovog razloga, koriste se različiti omekšivači vode, sa sposobnošću da apsorbuju jone metala i onemoguće aglomeraciju soli na površinama. Polimerni materijali, posebno polikarboksilati, mogu se koristiti za sprečavanje ovih problema. U ovom radu je ispitivan uticaj molekulske mase i molekulskog sastava poli(akrilna kiselina – ko – maleinska kiselina) karboksilatnih kopolimera na apsorpciju kalcijumovih soli. Kopolimeri su sintetisani postupkom radikalne polimerizacije u vodenom rastvoru korišćenjem kalijum-persulfata kao inicijatora i jona gvožđa (Fe²⁺) kao regulatora dužine lanaca. Molekulske strukture dobijenih polimera analizirane su FT-IR metodom i potvrđeno je da je dobijeni polimer kopolimerne strukture. Srednja molekulska masa i stepen polidisperznosti uzoraka određeni su GPC metodom. Rezultati merenja molekulskih masa pokazuju da sa povećanjem udela Fe²⁺ jona opada molekulska masa kopolimera. Prisustvo uređene strukture potvrđeno je korišćenjem difrakcije X-zraka. Rezultati ispitivanja kapaciteta dispergovanja dobijenih kopolimera pokazali su da se sa smanjenjem molekulske mase smanjuje kapacitet dispergovanja soli kalcijum-karbonata.

Ključne reči: poli(akrilna kiselina – ko – maleinska kiselina), apsorpcija metalnih jona, polikarboksilati.

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Dekolorizacija obojene otpadne vode pomoću sorbenta napravljenog od prirodnih celuloznih vlakana

Izvod

Ovaj rad se bavi zaštitom okoline od emisije obojene otpadne vode tekstilne industrije. Radi se o obezbojavanju uz pomoć sorbenta dobijenog od prirodnih celuloznih otpadnih vlakana pamuka i konoplje. Uklanjanje reaktivne boje sorbentom iz vodenog rastvora ispitivano je pod različitim uslovima. Utvrđeno je da adsorpcija zavisi od vremena kontaktiranja, početne koncentracije boje i pH rastvora. Korišćeni sorbent je relativno fino rasuti materijal sa heterogenim poroznim česticama, razuđenog oblika i forme, dimenzija ispod 0,7 mm. Prema rezultatima kvantitativnog sastava sorbenta zaključuje se da dominira ugljenik, količina ugljenika 67,26 %. Maksimum stepena uklanjanja boje dešava pri pH 2-3 (68,5 %). Adsorbovana količine boje na sorbentu sa vremenom raste sa povećanjem početne koncentracije. Izotermni modeli, Langmuir i Freundlich, vrlo dobro opisiju uklanjanje reaktivne boje iz vodenog rastvora uz pomoć sorbenta (koeficijenti determinacija = ili > 0,9), uz činjenicu da se prednost daje nelinearnom modelu Freundlich-a koji najbolje opisuje eksperimentalne podatke.

Ključne riječi: pamučna vlakna, konopljina vlakna, reaktivna boja, sorbent, obezbojavanje, Langmuir, Freundlich.

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Optičke posebnosti različitih molekulskih kristalnih nanofilmova

Izvod

Primenom ranije formiranog modela molekulskih nanofilm kristalnih struktura u ovom radu teorijski su istražene i izučene promene optičkih osobina usled prisustva različitih granica ultratankih uzoraka. Pomoću nađenog zakona disperzije eksitona i teorije odziva sistema na spoljašnju perturbaciju, određena je relativna dinamička permitivnost kao i optičke osobine (refraktancija, apsorbancija, reflektancija i transparencija) ovih ultratankih dielektričnih filmova. Rezultati su pokazali da granični parametri diktiraju izmenu prelamanja, pojavu diskretne transparencije i apsorpcije, kao i da menjaju položaj i broj apsorpcionih pikova.

Ključne reči: tanki film, eksitoni, Grinove funkcije, permitivnost, prelamanje, apsorpcija, transparencija.

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OPTICAL PECULIARITIES OF VARIOUS MOLECULAR CRYSTALLINE NANOFILMS

Abstract

By applying the previously established model of molecular nanofilm crystalline structures, in this paper we theoretically investigated and studied changes in optical properties due to the presence of boundaries of ultrathin film samples. With founded exciton dispersion law and theory of system’s response to an external perturbation, the relative dynamic permitivity and the optical properties (absorption, refraction, reflection and transparency indices) of these ultrathin dielectric films were determined. The results have shown that boundary perturbation parameters could change refraction, appearance of discrete transparency and absorption as well as that could change position and number of absorption peaks.

Keywords: Thin film, excitons, Green’s functions, permitivity, refraction, absorption, transparency.

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Organic pollutants in water samples of Vjosa river – Albania

Abstract

The findings reported here belong to a study on determination of organochlorine pesticides, their residues, polychlorinated biphenyls, polyaromatic hydrocarbons and BTEX  concentrations in water samples of Vjosa River (Albanian part). The Vjosa River in Albania is one of Europe’s last living wild rivers. Water samples were taken in 12 stations starting from Sarandoporo (Leskovik, Kolonje) to Vjosa river mouth (Adriatic Sea), in March 2017. Organochlorine compounds and PCB markers were extracted using liquid-liquid technique using n-hexane as extracting solvent. PAHs were extracted also using liquid-liquid technique using dichloromethane as extracting solvent. After extraction the  organic  phase was dried with Na₂SO₄ anhidrous,  for removing water. A Florisil column was used for the sample clean-up. After the concentration to 1 ml, the samples were injected in Varian 450 GC equiped with ECD and FID detectors. BTEX were extracted using HS/SME technique with PDMS fiber. Found data shown persistent levels of pesticides and their metabolites in water samples because their previous use. PCBs, PAHs and BTEX were found also for all samples. Their presence could be because of anthropogenic and automobilist impact in waters of Vjosa River. The found levels for organic pollutants in waters of Vjosa River were lower than reported levels for other ecosystems in Albania.

Keywords: Vjosa River, organochlorine pesticides, PCB, PAH, BTEX, water samples, GC/ECD/FID

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ORGANSKI ZAGAĐIVAČI U UZORCIMA VODE REKE VJOSA – ALBANIJA

Izvod

Ispitivanja koja su u ovom radu prikazana pripadaju studiji o određivanju organohlornih pesticida, njihovih ostataka, polihloriranih bifenila, aromatičnih ugljovodonika i koncentracija BTEKS u uzorcima vode reke Vjosa (albanski dio). Reka Vjosa u Albaniji je jedna od poslednjih živih divljih reka u Evropi. Uzorci vode uzeti su na 12 mesta počevši od Sarandopora (Leskovik, Kolonje) do ulivanja reke Vjosa u Jadransko more, u mesecu martu 2017. godine. Organohloridna jedinjenja i PCB markeri su ekstrahovani tečnom-tečnom tehnikom, koristeći n-heksan kao ekstrakcioni rastvarač. PAH uzorci su ekstrahovani koristeći tehniku tečno-tečno, koristeći dihlormetan kao ekstrakcioni rastvarač. Nakon ekstrakcije organska faza je osušena sa Na₂S0₄ anhidrovanim, za uklanjanje vode. Za čišćenje uzorka korišćena je kolona Florisil. Nakon koncentrisanja do 1 ml, uzorci su injektirani u Varian 450 GC, opremljenim ECD i FID detektorima. BTEKS su ekstrahovani korišćenjem tehnike HS / SME sa PDMS vlaknom. Dobijeni podaci pokazuju razne koncentracije pesticida i njihovih metabolita u uzorcima vode zbog njihove prethodne upotrebe. PCB, PAH i BTEKS su pronađeni u svim uzorcima vode. Njihovo prisustvo može biti zbog antropogenih uticaja i uticaja saobraćaja na vodu reke Vjosa. Utvrđeni nivoi organskih zagađujućih materija u vodama reke Vjosa bili su niži od prijavljenih koncentracija za druge ekosisteme u Albaniji.

Ključne reči: reka Vjosa, organohlorni pesticidi, PCB, PAH, BTEKS, uzorci vode, GC/ECD/FID.

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Preparation of sustainable asphalt pavements using polyethylene terephthalate waste as a modifier

Abstract

Industrial development and contemporary life style led to spread a large amounts of non-biodegradable plastic waste. This paper aims to study the effects of recycling polyethylene terephthalate (PET) plastic waste which is a type of disposable plastic packaging waste as an asphalt modifier, to create a sustainable asphalt pavement and improving the rheological properties and temperature susceptibility. PET waste was blended with asphalt cement in three percentages (0.5%, 0.75%, and 1.0%) by mass of asphalt cement. The performance of modified asphalt samples have been studied and compared with an unmodified asphalt binder. The penetration, softening point and ductility were carried out to evaluate the influence of adding waste PET to asphalt on binder characteristics, binder stiffness at different temperatures also studied and all markedly improved. The results show that adding PETW has a significant effect on the rheological behavior and binder stiffness in high temperatures. This study indicate that waste PET has enhance asphalt properties to minimize the paving costs and reduce solid waste environmental problems.

Keywords: asphalt; moifier; polyethylene terephthalate waste; physical properties.

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Kvantifikovanje oblika nanočestica: segmentacija i mera izduženosti

Izvod

Uticaj oblika nanočestica na magnetna svojstva nanočestičnih materijala je često istican, ali nije mnogo proučavan u literaturi. U cilju boljeg razumevanja magnentih svojstava nanomaterijala veoma važan korak je merenje oblika korišćenjem deskriptora oblika. Kao jedan od najčešćih deskriptora korišćena je mera izduženosti nanočestica, dok su eksperimentalni rezultati dobijeni korišćenjem TEM slika nanočestica hematita. U cilju analize oblika slike su podvrgnute segmentaciji čime su dobijene izolovane nanočestice, a zatim je izmerena izduženost izdvojenih nanočestica. Mera izduženosti ε(S) koja je predložena i korišćena u eksperimentu daje intuitivno očekivane rezultate. Nasuprot tome, ukazano je na to da kao i svi drugi desriptori oblika i mera ε(S) pored nesumnjivih prednosti ima i određene nedostatke. Stoga se predlaže korišćenje više različitih deskriptora što obezbeđuje bolju i precizniju karakterizaciju oblika nanočestica čime se mogu izbeći nedostaci koje pojedini deskriptori imaju.

Ključne reči: Analiza oblika, nanočestice, izduženost, deskriptori oblika, segmentacija.

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QUANTIFYING THE SHAPE OF NANOPARTICLES: SEGMENTATION AND ELONGATION MEASURE

Abstract

The influence of the shape of nanoparticles on the magnetic properties of nanoparticle materials is often mentioned, but is not much studied in literature. In order to better understand the magnetic properties of nanomaterials a very important step is to measure shapes using the shape descriptors. As one of the most common descriptors, the elongation measure of nanoparticles was used, while experimental results were obtained using TEM images of hematite. With the goal of shape analysis the images were segmented to produce isolated nanoparticles and after that the elongation of separated nanoparticles was measured. The elongation measure ε(S) proposed and used in the experiment gives intuitively expected results. On the opposite, it has been pointed out that, like all other shape descriptors ε(S), besides the undoubted advantages, there are certain disadvantages. Therefore, it is proposed to use several different descriptors, which provide better and more precise characterization of nanoparticles, which can avoid the flaws that some descriptors have.

Keywords: Shape analysis, nanoparticles, elongation, shape descriptors, segmentation.

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Uredništvo/Editorial

Ispravka

Proizvodnja vodonika gasifikacijom biomase, Zastita Materijala 58 (2),
228 – 234  (2017), doi:10.5937/ZasMat1702228J

Milovan Jotanović, Vladan Mićić*, Stefan Pavlović

Univerzitet u Istočnom Sarajevu, Tehnološki fakultet Zvornik, Zvornik, BiH

 

U ovom radu su uočene dve greške u tekstu objavljenog rada.

1. Prva greška se odnosi na zamenu reference broj 3 koja je pogrešno bila upisana od strane autora:

Prethodna referenca:

[3] D.E.Cole (2007) Issues facing the Auto industry: Alternative Fuels, Technologies and Policies ACP Meeting Eagle Crest Conference Center, 20, p.2007.

Nova referenca:

[3]  M.Martin, I.E.grosman (2010) Energy optimization of hydrogen production from biomass, Computers and chemical engineering, 35(9), 1798-1806.

 

2. Druga greška je pogrešna kategorizacija rad.

Stoji: Naučni rad

Treba da bude: Pregledni rad.

Ova greška je nastala u toku tehničke pripreme rada za objavljivanje i primećena je od strane autora.

Uredništvo časopisa se zahvaljuje autorima na uočenim greškama u radu.

 

Correction

Hydrogen production by biomass gasification, Zastita Materijala 58 (2),
228 – 234  (2017), doi:10.5937/ZasMat1702228J

Milovan Jotanović, Vladan Mićić*, Stefan Pavlović

Univerzitet u Istočnom Sarajevu, Tehnološki fakultet Zvornik, Zvornik, BiH

 

Two errors were noted in the text of the published paper.

1. The first error relates to the replacement of reference number 3 which was incorrectly typed by the authors:

Previous Reference:

[3] D.E.Cole (2007) Issues facing the Auto industry: Alternative Fuels, Technologies and Policies ACP Meeting Eagle Crest Conference Center, 20, p.2007.

New Reference:

[3]  M.Martin, I.E.grosman (2010) Energy optimization of hydrogen production from biomass, Computers and chemical engineering, 35(9), 1798-1806.

 

2. The second error is the wrong categorization of the paper.

It says: Scientific paper
It should be: Review paper.

This error occurred during the technical preparation of publication paper and was noticed by the authors.

The editorial staff of the journal thanks the authors on the observed mistakes in their paper.