Zaštita Materijala 2. 2020

 

Tools for optimizing the operating conditions of waste-to-energy plant

Abstract

The efficient use of energy and resources is important from the point of environmental responsibility, but at the same time, it can be an opportunity towards obtaining economic value. Waste-to-energy (WtE) plants have the dual objective first to reduce the amount of waste sent to landfills, and second to generate electricity, heat and biogas. Tracking the flows of energy and materials within WtE system could be convenient optimization tool for waste treatment process. Through modeling and simulation of complex operating systems, it is manageable to present the actual operation states and conditions, and in case of modified operation conditions, possible treatment results. To achieve better operating performances chosen models can analyze, adjust and improve the WtE process in accordance to desired parameters. This paper gives an insight of some of the most adequate tools for modeling of WtE plants.

Keywords: Waste-to-energy, tools, optimization.

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Alati za optimizaciju radnih uslova postrojenja za energetsko iskorišćenje otpada  

Izvod

Efikasno korišćenje energije i resursa važno je sa stanovišta odgovornosti za životnu sredinu, ali istovremeno treba imati u potencijalnu ekonomsku dobit. Postrojenja za proizvodnju energije iz otpada (eng. Waste-to-Energy, WtE) imaju dvostruki cilj, da smanje količinu otpada koja se šalje na deponije, kao i da omoguće proizvodnju električne energije, toplote i biogasa. Praćenje protoka energije i materijala unutar ovih postrojenja, može da predstavlja praktičan alat za optimizaciju tretmana otpada. Pomoću modeliranja i simulacije složenih operativnih sistema, moguće je prikazati stvarna radna stanja i uslove procesa, a u slučaju izmenjenih uslova rada i moguće rezultate tretmana. U cilju postizanja boljih operativnih performansi, odabrani modeli mogu vršiti analizu, mogu prilagoditi i poboljšati proces dobijanja generisanja energije iz otpada u skladu sa željenim parametrima. Ovaj rad daje uvid u neke od najprikladnijih alata za modeliranje postrojenja za dobijanje energije iz otpada.

Ključne riječi: Energija iz otpada, alati, optimizacija.

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Space-time propagation of  air pollution from dot source-quasi 1D model 

Abstract

The problem of pollution – especially air pollution in big cities, has arisen with rapid technological development. This paper analyzes the propagation of air pollution originating from periodical dot sources. Pollution will be is examined as a quasi-one-dimensional directed from the source, in case when diffusion processes, absorption and airflow occur. The partial differential equation describing all given processes is solved numerically for the adopted real parameters of the mentioned processes. The time change of the concentration of air pollution with distance from its source was determined.

Keywords: Air-pollution, periodical dot source, quasi 1D propagation, diffusion processes, absorption, airflow, space-time distribution

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Prostorno-vremensko prostiranje aerozagađanja iz tačkastog izvora – KVAZI 1D  MODEL 

Izvod

Problem zagađenja – posebno vazduha u velikim gradovima, nastao je naglim tehnološkim razvojem. U radu je analizirano prostiranje zagađenja vazduha koji potiče iz periodičnih tačkastih izvora. Zagađenje se razmatra kao kvazi jedno-dimenziono usmereno od izvora, za slučaj kada nastaju difuzijski procesi, apsorpcija i protok vazduha. Parcijalna diferencijalna jednačina koja opisuje sve date procese numerički se rešava za usvojene realne parametre pomenutih procesa. Određena je vremenska promena koncentracije aero-zagađenja sa udaljenjem od njenog izvora.

Ključne reči: Aero-zagađenje, periodični tačkasti izvor, kvazi 1D prostiranje, difuzioni procesi, apsorpcija, protok vazduha, prostorno-vremenska distribucija.

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Characterization of NiAl layers deposited by atmospheric plasma spray (APS)

Abstract

In this paper analyzed were the mechanical properties and microstructure of the Ni30Al coating layers deposited using atmospheric plasma spray (APS). For deposition of the coating applied was a composite Ni30wt.% Al powder, manufactured by mechanical alloying of granulation below – 180 µm. The coatings mechanical properties were analyzed by microhardness measuring with the HV_0.3 method and the bond strength by tension method. For the analysis of the microstructure of the coating layers applied was the method of light and scanning electron microscopy (SEM). Microhardness tests showed that the coating has a wide range of measured values ​​which indicate a heterogeneous multiphase lamellar microstructure of the coating, which was confirmed by metallographic examination of the layers. The multi-phase lamellar microstructure consisted of the initial solid α-Al, g-Ni solutions, formed solid b-NiAl and NiAl martensite solutions, intermetallic compounds g’-Ni₃Al and Ni₂Al₃ and the oxide g-Al₂O₃ phase formed by oxidation of molten Al particles. Based on these tests given was an evaluation of the quality of the coating. The results of the experiment showed that the technological process of production of composite powders significantly affects the mechanical properties and structure of the coating layers.

Keywords: atmospheric plasma spray (APS), microstructure, Ni30wt.% Al, microhardness, bond strength.

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Karakterizacija   NiAl  slojeva deponovanih atmosferskim plazma sprejom (APS)

Izvod

U ovom radu analizirane su mehaničke osobine i mikrostruktura slojeva prevlake Ni30Al deponovane atmosferskim plazma sprejom (APS). Za depoziciju prevlake primenjen je kompozitni prah Ni30tež.%Al proizveden mehaničkim legiranjem granulacije ispod – 180 µm. Mehaničke karakteristike prevlake analizirane su merenjem mikrotvrdoće metodom HV_0.3 i čvrstoće spoja metodom na zatezanje. Za analizu mikrostrukture slojeva prevlake primenjena je metoda svetlosne i skening elektronske mikroskopije (SEM). Ispitivanja mikrotvrdoće su pokazala da prevlaka ima širok opseg izmerenih vrednosti koje ukazuju na višefaznu heterogenu lamelarnu mikrostrukturu prevlake, koja je potvrđena metalografskaim ispitivanjem slojeva. Višefazna lamelarna mikrostruktura se sastojala od polaznih čvrstih rastvora α-Al, g-Ni, formiranih čvrstih rastvora b-NiAl i NiAl martenzita, intermetalnih jedinjenja g’-Ni₃Al i Ni₂Al₃ i oksidne faze g-Al₂O₃ nastale oksidacijim istopljenih čestica Al. Na osnovu sprovedenih ispitivanja dala se ocena kvaliteta prevlake. Rezultati eksperimenta su pokazali da tehnološki postupak proizvodnje kompozitnih prahova bitno utiče na mehaničke karakteristike i strukturu slojeva prevlake.

Kljućne reči: atmosferski plazma sprej (APS), mikrostruktura, Ni30tež.%Al, mikrotvrdoća, čvrstoća spoja.

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Immobilization of heavy metal ions Zn²⁺, Ni²⁺, Pb²⁺ and Cu²⁺ in the structure of cement-based materials

Abstract

Natural zeolite and bentonite were utilized as mineral additives in the mix-design of environmentally safe cement-based building materials. The adsorptive abilities of these two clayey raw materials, i.e. their affinity to immobilize heavy metal ions Zn²⁺, Ni²⁺, Pb²⁺ and Cu²⁺ were investigated. Single- and multi-solutions of Zn²⁺, Ni²⁺, Pb²⁺ and Cu²⁺ were prepared for the experiment. The obtained results were submitted to analysis via pseudo-first and pseudo-second order kinetic models. Langmuir and Freundlich isotherms were analyzed. Bentonite exhibited better adsorption affinity than zeolite towards all four investigated cations. As a proof, a leaching test was conducted on seven different cement binders with different mineral additives (fly ash, zeolite, bentonite). The leachates obtained on the samples of cement with addition of fly ash and clay (either zeolite or bentonite) contained lower concentrations of Zn²⁺, Ni²⁺, Pb²⁺ and Cu²⁺ ions than leachates obtained on the samples of cement binder with fly ash solely as a result of adsorption and hydration mechanisms that immobilized heavy metals within cementitious composites.

Keywords: Ion-exchange; Kinetics; Clayey adsorbents; Leaching control; Cement.

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Imobilizacija teških metalnih jona  Zn²⁺, Ni²⁺, Pb²⁺ I Cu²⁺ u strukturi materijala na bazi cementa  

Izvod

Prirodni zeolit i bentonit korišćeni su kao mineralni dodaci u mešavinskom dizajnu ekološki sigurnih građevinskih materijala na bazi cementa. Ispitane su adsorptivne sposobnosti ove dve glinene sirovine, tj. njihov afinitet da imobiliziraju jone teških metala Zn²⁺, Ni²⁺, Pb²⁺ i Cu²⁺. Za eksperiment su pripremljeni pojedinačni i multi-rastvori Zn²⁺, Ni²⁺, Pb²⁺ i Cu²⁺. Dobijeni rezultati su analizirani pomoću kinetičkih modela pseudo prvog i pseudo drugog reda. Analizirane su izoterme Langmuira i Freundlicha. Bentonit je pokazao bolji adsorpcioni afinitet od zeolita prema sva četiri ispitivana katjona. Kao dokaz, ispitano je ispitivanje ispiranja na sedam različitih veziva za cement sa različitim mineralnim dodacima (leteći pepeo, zeolit, bentonit). Eluati dobijeni na uzorcima cementa sa dodatkom letećeg pepela i gline (bilo zeolita ili bentonita) sadržavale su niže koncentracije jona Zn²⁺, Ni²⁺, Pb²⁺ i Cu²⁺ u odnosu na eluat dobijen na uzorcima cementnog veziva sa letećim pepelom. Razlog za dobijanje ovakvih rezultata su adsorpcioni i hidratacioni mehanizmi koji imobiliziraju teške metale u cementnim kompozitima.

Ključne reči: Jon-razmena; kinetika; glineni adsorbenti; izluživanje; cement.

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Review: Investigation of the electrochemical properties of beta blockers and ACE inhibitors by cyclic voltammetry

Anstract

Hypertension is the most common cardiovascular disease in developed and developing countries, affecting about 20-30% of the adult population. It is an independent risk factor for cardiovascular disease and is associated with an increased incidence of stroke and coronary heart disease. Several types of antihypertensive drugs are used worldwide to control risk factors. Perindorpil is one of the medicines used to treat high blood pressure, heart failure or stable coronary artery disease. Metoprolol is a cardioselective beta1-adrenergic receptor blocker in the heart. They block the effect of adrenaline and noradrenaline on beta-adrenergic receptors in the body. Previous scientific research in the field of electrochemistry has enabled the development of sensitive, reliable and cheaper instruments that have significant contributions in the field of drug development and analysis. Cyclic voltammetry examines the activity of the drug itself, the effect of concentrations as well as the influence of different scan rates. We conclude that with an increase in the concentration of both Perindopril and Metoprolol, an increase in the current peak in the area of reduction is observed.

Keywords: Beta blocker, ACE inhibitor, cyclic voltammetry.

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Pregled: Ispitivanje elektrohemijskih osobina beta blokatora i  ACE inhibitora metodom ciklične voltametrije 

Izvod

Hipertenzija je najčešća kardiovaskularna bolest u razvijenim zemljama i u zemljama u razvoju koja utiče na oko 20-30% odrasle populacije. Riječ je o nezavisnom faktoru rizika za kardiovaskularne bolesti i povezan je sa povećanom učestalosti moždanog  udara i koronarne bolesti srca. Da bi se kontrolisali faktori rizika u svijetu se koristi nekoliko vrsta antihipertenzivnih lijekova. Perindopril je jedan od lijekova koji se koristi za liječenje visokog krvnog pritiska, srčane insuficijencije ili stabilne bolesti koronarne arterije. Metoprolol je kardioselektivni blokator beta1-adrenergičnih receptora u srcu. Oni blokiraju dejstvo adrenalina i noradrenalina na beta adrenergične receptore u tijelu. Dosadašnja naučna istraživanja iz oblasti elektrohemije omogućila su razvoj osjetljivih, pouzdanih i jeftinijih instrumenata koji imaju značajan doprinos u oblasti razvoja lijekova i analize. Cikličnom voltametrijom ispitujemo samu aktivnost lijeka, uticaj koncentracija kao i uticaj različitih brzina skeniranja. Došli smo do zaključka da se sa povećanjem koncentracije i Perindoprila i Metoprolola, uočava povećanje strujnog pika u oblasti redukcije.

Ključne riječi: Beta blokator, ACE inhibitor, ciklična voltametrija.

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Corrosion behaviour of stainless steel EN 1.4301 in acid media in presence of PBTCA inhibitor

Abstract

In this study, corrosion behaviour of stainless steel in 0.5 M and 1 M hydrochloric acid was examined. Also, commercial corrosion inhibitor which contain 2-phosphonobutane-1,2,4-tricarboxylic acid (PBTCA) is examined as potential inhibitor for stainless steel EN 1.4301 in 0.5 M hydrochloric acid. For experimental research it was used DC-technique (Tafel extrapolation, linear polarization method and potentiodynamic polarization). The obtained results show that the inhibitor is effective in mentioned acid environment and the protection efficiency depends primarily on the concentration of the inhibitor. Based on the obtained results this inhibitor has moderate inhibition efficiency, since the highest efficacy was achieved E_i = 55.7%. According to the corrosion mechanism the inhibitor is behaved as a mixed inhibitor.

Keywords: Corrosion rate, protection efficiency, DC-technique.

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Koroziono ponašanje nerđajućeg čelika  EN 1.4301 u kiseloj sredini u prisustvu PBTCA  inhibitora

Izvod

U ovom radu ispitano je koroziono ponašanje nerđajućeg čelika u 0,5M i 1M hlorovodičnoj kiselini. Takođe, ispitan je komercijalni inhibitor korozije koji sadrži 2-fosfonobutan-1,2,4-trikarboksilnu kiselinu (PBTCA) kao potencijalni inhibitor korozije nerđajućeg čelika EN 1.4301 u 0,5M hlorovodičnoj kiselini. Za eksperimentalna istraživanja korištena je DC tehnika (Tafelova ekstrapolacija, metoda linearne polarizacije i potenciodinamička polarizacija). Dobijeni rezultati pokazuju da je inhibitor efikasan u navedenom kiselom mediju, a efikasnost zaštite prvenstveno zavisi od koncentracije inhibitora. Na osnovu dobijenih rezultata, inhibitor pokazuje inhibicijsku efikasnost, budući da najveća postignuta efikasnost iznosi E_i = 55,7%. Prema mehanizmu djelovanja inhibitor se ponaša kao mješoviti inhibitor.

Ključne riječi: brzina korozije, efikasnost zaštite, DC-tehnika.

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The influence of cupric ions on the corrosion behavior CuZn-42 brass in presence of corrosion inhibitors in acidic medium

Abstract

In this work we are presented our results of investigations of corrosion behavior of CuZn-42 brass in acid sulphate solution, in presence of corrosion inhibitors and cupric ions. Based on the recorded anodic polarisation curves, it was concluded that with increased concentrations of cupric ions, the values of corrosion current densities also increase. The effect of corrosion inhibitors on the corrosion behaviour of brass is analyzed in the work and it is concluded that the concentration of inhibitors is 10^-2% shows inhibition effect.

Keywords: brass, deformation, cupric ion, corrosion, polarisation.

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Uticaj kupri jona na koroziono ponašanje mesinga   CuZn-42  u prisustvu inhibitora korozije u kiseloj sredini 

Izvod

U ovom radu dati su rezultati istraživanja korozionog ponašanja mesinga CuZn-42 u kiseloj sredini, u prisustvu inhibitora korozije i kupri jona. Na osnovu snimljenih anodnih polarizacionih krivi, zaključeno je da se sa povećanjem koncentracije kupri jona povećavaju i vrednosti gustina korozionih struja. U radu je analiziran i uticaj inhibitora korozije na koroziono ponašanje ispitivanog mesinga i zaključeno je da koncentracija inhibitora 10^-2% ima uticaj na smanjenje brzine korozije.

Kljućne reči: mesing, deformacija, bakar(II)-jon, korozija, polarizacija.

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New standards and regulations on formaldehyde emission from wood-based composite panels

Abstract

The urea-formaldehyde (UF) adhesive is still most important adhesive system in the production of interior grade particleboards and medium density fibreboards (MDF). However, the furniture and interior fitments, incorporating these products, present one of the sources of formaldehyde emission into the indoor air. The recognition of formaldehyde as a substance that presents the risk for a human health had a strong impact on wood-based panels industry, as it came under constrains by the number of national and international regulations. Hence, this paper presents the overview of standards and regulations that define formaldehyde emission limits for wood-based panels today, and of a special interest for a wood-based panels market in the Republic of Serbia. The paper also gives an overview on a possible methods and procedures for the production of wood-based panels with low or no formaldehyde emission.

Keywords: wood-based panels, UF adhesive, formaldehyde, emission standards.

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Savremeni standardi i propisi o emisiji formaldehida iz kompozitnih ploča drveta   

Izvod

Urea-formaldehidni (UF) adheziv je još uvek jedan od najvažnijih adhezivnih sistema u proizvodnji ploča iverica i ploča vlaknatica srednje gustine (MDF). Međutim, nameštaj i elementi enterijera koji sadrže ove proizvode predstavljaju jedan od izvora emisije formaldehida u unutrašnjem prostoru. Prepoznavanje formaldehida kao supstance štetne po zdravlje čoveka imalo je snažan uticaj na sektor proizvodnje ploča na bazi drveta, pošto su se ovi proizvodi našli pod ograničenjima od strane brojnih nacionalnih i međunarodnih regulativa. Shodno tome, ovaj rad predstavlja pregled standarda i regulativa koji danas definišu emisione granice za ploče na bazi drveta, a od značaja su za tržište ovih ploča u Republici Srbiji. Ovde se, takođe, daje i kratak pregled metoda i procedura u proizvodnji ploča na bazi drveta sa veoma niskom ili bez emisije formaldehida.

Ključne reči: ploče na bazi drveta, UF adheziv, formaldehid, standardi emisije

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