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The purpose of the study was to identify and predict the optimized parameters for phosphoric acid production. This involved modeling the crystal reactor, UCEGO filter (as a detailed model of the filter is not available in Aspen Plus or other simulation software), and acid separator using Sci-Lab to develop Cape-Open models. The simulation was conducted using Aspen Plus and involved analyzing 10 different phosphates with varying qualities and fractions of P2O5 and other minerals. After a successful simulation, a sensitivity analysis was conducted by varying parameters such as capacity, filter speed, vacuum, particle size, water temperature for washing the filtration cake, flow of recycled acid and strong acid from the separator below the filter, flow of slurry to reactor 1, temperature in reactors, and flow of H2SO4, resulting in nearly one million combinations. To create an algorithm for predicting process parameters and the maximal extent of recovering H3PO4 from slurry, ANN models were developed with a determination coefficient of 99%. Multi-objective optimization was then performed using a genetic algorithm to find the most suitable parameters that would lead to a higher reaction degree (96–97%) and quantity of separated H3PO4 and lower losses of gypsum. The results indicated that it is possible to predict the influence of process parameters on the quality of produced acid and minimize losses during production. The developed model was confirmed to be viable when compared to results found in the literature.

Prvi deo doktorske disertacije sadrži uvid u procenu ekološkog uticaja proizvodnje električne i toplotne energije u Srbiji. Kao najčešći energent koristi se lignit, pa su poređeni eko-energetski uticaji lignita i rastvorenog naftniog gasa. Rastvoreni naftni gas je razmatran kao potencijalni energent u tri scenarija: • na bakljama, • u kotlovima na naftnim poljima, • u kogenerativnim postrojenjima na naftnim poljima. Ispitana je ekološka isplativost tri pomenuta scenarija kroz analizu materijalih tokova i procene uticaja na životnu sredinu pomoću LCA (life cycle assessment) metodoligije i podacima koji su prikupljeni na osnovu merenja na naftnim poljima. Koristiće se parametri koji ukazuju na uticaj globalnog zagrevanja, GWP (global warming potential) i iscrpljivanje energetskih resursa, CED (cumulative energy demand) uz osvrt na osetljivost sistema na iskorišćenje toplotne energije. Detaljna ekonomska analiza i gubici koji proističu od emisija gasova koji izazivaju efektat staklene bašte su procenjeni Maihach-ovom metodom. Metoda omogućava određivanje troškova tj. uštede nastale smanjenjem emisije CO2 i drugih gasova koji izazivaju efekat staklene bašte usled sagorevanja lignita i rastvorenog naftnog gasa u tri scenarija. Drugi deo disertacije bavi se uspostavljanjem simulacije kogenerativnih postrojenja u softveru ASPEN PLUS kako bi se stekao uvid u energetske i materijalne bilanse procesa što će omogućava precizniju procenu ukupne efikasnosti sistema. Ukupna efikasnost sistema isključivo zavisi od uspešnog iskorišćenja toplotne energije što je usko vezano za ekonomsku isplativost izgradnje postrojenja. Uspešna računarska simulacija kogenerativnih postrojenja pruža uvid u variranje procesnih parametara pomoću kojih je moguće izvršiti optimizaciju kogenerativnih postrojenja na naftnom polju u odnosu na sastav gasa. Rezultati ove doktorske disertacije daju detaljan uvid u rad kogenerativnih postrojenja, što doprinosi daljem razvoju tehnologije kogeneracije na naftnim, The first part of the doctoral dissertation contains an insight into the assessment of the environmental impact of electricity and heat production in Serbia. Lignite is used as the most common energy source, so the eco-energy effects of lignite and dissolved petroleum gas are compared. Dissolved petroleum gas was considered as a potential energy source in three scenarios: • on torches, • in boilers in oil fields, • in cogeneration plants in oil fields. The ecological viability of the three mentioned scenarios was examined through the analysis of material flows and environmental impact assessment using LCA (life cycle assessment) methodology and data collected on the basis of measurements in oil fields. Parameters indicating the impact of global warming, GWP (global warming potential) and depletion of energy resources, CED (cumulative energy demand) will be used, with reference to the sensitivity of the system to the use of thermal energy. Detailed economic analysis and losses resulting from greenhouse gas emissions were estimated by the Maihach method. The method enables the determination of costs, ie. savings resulting from reduced emissions of CO2 and other greenhouse gases due to the combustion of lignite and dissolved petroleum gas in three scenarios. The second part of the dissertation deals with the establishment of simulation of cogeneration plants in the software ASPEN PLUS in order to gain insight into the energy and material balances of the process, which allows a more accurate assessment of the overall efficiency of the system. The overall efficiency of the system depends exclusively on the successful use of thermal energy, which is closely related to the economic profitability of plant construction. Successful computer simulation of cogeneration plants provides insight into the variation of process parameters by which it is possible to optimize cogeneration plants in the oil field in relation to the gas composition. The results of this doctoral dissertat

Predmet istraživanja ove doktorske disertaciji je uticaj fizičko-hemijskih svojstava ekološki prihvatljivih mineralnih i biljnih ekstender ulja na svojstva proizvoda gume baziranih na prirodnom kaučuku, kao i na potrošnju električne energije potrebnu za namešavanje takvih proizvoda. U prvoj fazi istraživanja izvršena je karakterizacija i određivanje fizičko-hemijskih svojstava šest mineralnih i šest biljnih procesnih ulja. Sledeća faza eksperimentalnog programa obuhvatila je namešavanje ekstender ulja u različitim udelima u elastomernoj, kaučukovoj smeši. Cilj je bio da se ispita uticaj prirode i udela ekstender ulja na svojstva dobijene elastomerne smeše prirodnog kaučuka i gume, kao i potrošnju električne energije pri namešavanju kaučukove smeše. Prilikom namešavanja kaučukove smeše variran je udeo ekstender ulja u opsegu od 0 do 30 phr. Za namešavanje komponenata je korišćen laboratorijski mešač u kom je temperatura u svim zonama zagrevanja bila konstantna (90°C). Namešavanja je započinjalo uz istovremeno uključivanje ampermetra i voltmetra koji su povezani na elektromotor mešača i računar koji beleži vrednosti jačine struje i napona tokom čitavog perioda namešavanja. Na osnovu toga je izračunata utrošena snaga pri namešavanju kaučukove smeše. Svaka dobijena kaučukova smeša je pripremljena i vulkanizovana na hidrauličnoj presi, te su određena svojstva takvog uzorka (tvrdoća (Shore A), zatezna čvrstoća , prekidno izduženje , modul pri 100% izduženju, modul pri 300% izduženju, brzina vulkanizacije, vreme početka vulkanizacije kaučukove smeše, optimalno vreme vulkanizacije i razliku obrtnih momenata). Na osnovu eksperimentalno određenih i izračunatih vrednosti nezavisnih i zavisnih promenljivih statistički je analiziran uticaj sadržaja i svojstava ekstender ulja na osobine kaučukove smeše i utrošenu snagu pri namešavanju svake kaučukove smeše. Ispitivanje uticaja ekološki prihvatljivih ekstender ulja na svojstva gume u okviru ove doktorske disertacije omogućava defi, This Ph.D. thesis investigates the influence of environmentally friendly extender oil properties on natural rubber based performances and power consumption during the effective mixing phase. Six mineral and six vegetable extender oils were used for experimental program. Extender oil properties were determined using standard methods. The experiments were carried out in a broad range of the extender oil concentrations. The goal was to study the influence of nature and amount of extender oil on rubber performances and power consumption. The extender oil concentration was varied from 0 to 30 phr. The experiments were performed on a laboratory internal batch mixer. The mixing was done at constant temperature (90°C). Power consumption during the effective mixing phase was calculated from measured voltage and the current I in amps. The following rubber properties were measured: hardness (Shore A), tensile strength, elongation at break, modulus at 100% elongation, modulus at 300% elongation, curing speed index, optimum curing time, scorch time and difference between maximum and minimum torques. For each natural rubber compound with varying amounts of extender oils, the statistical analysis was conducted and experimental data were fitted. This enabled an assessment of rubber process oil properties and selection of extender oil according to industrial requirements, sustainable development and environmental management. From an engineering point of view, the results of this Ph.D. thesis are the reliable source of information for oil-petrochemical and rubber industry, enabling the selection of new extender oils and estimation of power consumption during effective mixing of rubber ingredients. Furthermore, this investigation can provide the efficient

U mnogim granama tehnike javljaju se problemi merenja protoka fluida. Merne blende, zbog svojih mnogih prednosti predstavljaju najzastupljeniji instrument za merenje protoka fluida kroz cevovode. Sa druge strane njihova upotreba povećava troškove rada industrijskih postrojenja. Jedan od ciljeva ove doktorske disertacije bio je ispitivanje novih oblika mernih blendi u cilju uštede energije pri njihovom radu. U ovoj doktorskoj disertaciji predložen je algoritam ispitivanja novih oblika mernih blendi. Takođe je konstruisana i izrađena laboratorijska aparatura za njihovo ispitivanje kao i diferncijalni "U" manometar za merenje malih razlika pritisaka. U okviru ove doktorske disertacije dizajnirana su i ispitana tri nova oblika mernih blendi. Ušteda energije je postignuta dizajnom koji smanjuje otpor merne blende kao elementa cevovoda. Novi oblici mernih blendi, kao i jedna standardnog oblika koja je poslužila kao referentna, ispitani su prema predloženom algoritmu. U prvom koraku merne blende su dizajnirane u programskom paketu Solid Works. Zatim su, prema predloženom algoritmu, ispitane pomoću računarske simulacije u programskom paketu COMSOL Multiphysics. Po dobijanju zadovoljavajućih rezultata računarske simulacije, merne blende su izrađene na 3D štampaču, FDM postupkom i ispitane na laboratorijskoj aparaturi. Rezultati laboratorijskih ispitivanja su upoređeni sa rezultatima računarske simulacije. Upoređeni rezultati računarske simulacije i laboratorijskih ispitivanja su pokazali da je računarska simulacija dobro opisivala situaciju. Rezultati laboratorijskog ispitivanja su pokazali znatan efekat uštede energije. Takođe je utvrđeno da se pomoću računarske simulacije mogu dobiti podaci na osnovu kojih se može doneti odluka da li novi oblik merne blende treba korigovati ili ima smisla pristupiti laboratorijskom ispitivanju. Algoritam ispitivanja koji je predložen u ovoj doktorskoj disertaciji se pokazao efikasnim., In many domains of technology, there are problems with the measurement of fluid flow. Orifice plates, because of their many advantages, represent the most common instrument for measuring fluid flow through pipelines. On the other hand, their use increases the operating cost of industrial plants. One of the goals of this doctoral dissertation was to test new forms of orifice plates for a reason to save energy during their work. An algorithm for testing new forms of orifice plates is proposed. Also, the laboratory equipment for testing them was designed and made, as well as a differential "U" manometer for measuring small pressure differences. As part of this doctoral dissertation are designed and tested three new forms of orifice plates. Energy-saving was achieved by a design that reduces the resistance of the orifice plate as an element of the pipeline. New forms of orifice plates, as well as a standard shape, which served as a reference, were tested according to the present algorithm. In the first step, orifice plates are designed in the Solid Works software package. Then, according to the proposed algorithm, they were tested using computer simulation in COMSOL Multiphysics software package. After achieving satisfactory results of computer simulation, orifice plates are made on a 3D printer, using the FDM process and tested in the laboratory apparatus. The results of laboratory tests were compared with the results of computer simulations. Compared results of computer simulation and laboratory testing showed that computer simulation described the situation well. The results of the laboratory test showed a significant energy-saving effect. It was also found that computer simulation can obtain data that can decide whether a new form of orifice plate must be corrected or it makes sense to access laboratory testing. The algorithm proposed in this doctoral dissertation has proven effective.

Cilj ove doktorske disertacije je da dâ doprinos u proučavanju nedovoljno poznatih fenomena koalescentne filtracije, kako bi se smanjio obim potrebnih poluindustrijskih istraživanja prilikom projektovnja filtera za neku konkretnu primenu. Svi materijali korišćeni u ovoj doktorskoj disertaciji su otpadni materijali, čija primena kao filtarskog punjenja predstavlja poseban doprinos održivom razvoju. Jedan od ciljeva ove doktorske disertacije je proučavanje istovremenog uticaja promene permeabilnosti sloja i debljine vlakana na osobine sloja, pad pritiska i efikasnost separacije dispergovanog ulja iz kontinualne vodene faze. Uticaj geometrije sloja proučavan je na slojevima homogene i heterogene geometrije po dubini. Realizovano je detaljno ispitivanje izgleda, morfologije vlakana, kao i strukture sloja, izgleda i rasporeda njegovih pora, primenom skening elektronske mikroskopije i optičke mikroskopije. U radu je dat pregled istraživanja primene vlakana različite prirode (slobodnih i međusobno povezanih, krutih i elastičnih, različite debljine te time i različite vijugavosti) i njihovih slojeva. Takođe, dat je doprinos proučavanju istovremenog uticaja promena ulazne koncentracije dispergovane faze i permeabilnosti sloja. U veći deo ostvarenih istraživanja ukjučeno je i proučavanje uticaja prirode uljne faze, pri čemu je neophodno istaći da su sva korišćena ulja mineralnog porekla. Cilj optimizacije rada koalescera bio je da se pronađu uslovi u kojima se postiže maksimalna vrednost kritične brzine uz minimalni pad pritiska., The aim of this doctoral dissertation is to contribute to the study of insufficiently known phenomena of coalescent filtration, in order to reduce the number of pilot plant experiments required for designing filters for some specific applications. All the used materials are waste materials the use of which as a filter media contributes to sustainable development. One of the goals of this doctoral dissertation is to study the simultaneous effect of changes in bed permeability and fiber thickness on bed properties, pressure drop and the efficiency of the dispersed oil separation from a continuous aqueous phase. The effect of bed geometry was studied by applying the beds of homogeneous and heterogeneous geometry in depth. A detailed examination of the appearance and morphology of the fibers, as well as the structure of the bed and the appearance and arrangement of its pores, was performed by scanning electron microscopy and optical microscopy. The doctoral dissertation gives an overview of the testing of fibers of different nature (free and interconnected, rigid and elastic, of different thickness and thus of different meandering) and their beds. The simultaneous effect of the changes in the input dispersed phase concentration and the bed permeability was also investigated. Much of the conducted research includes the study of the impact of the nature of the oil phase, and it is necessary to point out that all used oils are mineral oils. The goal of optimizing the operation of a coalescer was to find the conditions providing the maximum critical velocity value with a minimum pressure drop.

U disertaciji je ispitana mogucnost korišcenja izluženih rezanaca šecerne repe za adsorpciju jona bakra u koloni sa nepokretnim slojem. Eksperimenti su izvedeni primenom Boks-Benkenovog eksperimentalnog dizajna na tri nivoa sa tri promenljive: koncentracija napojnog rastvora (50-150 mgL-1), masa adsorbenta (8-12 g) i pH napojnog rastvora (4,0-5,0). Dobijene prevojne krive su fitovane uobicajenim empirijskim modelima, Boart-Adamsovim i modelom doza-odziv. Na osnovu uocene asimetrije prevojne krive, predložen je novi matematicki model. Novi model predlaže prevojnu krivu koja se sastoji od dva dela, koji u zbiru daju kumulativnu krivu koja dosledno pokriva uocenu asimetriju. Uzimajuci u obzir najnižu prosecnu sumu kvadrata odstupanja, SSer (3,610-3) i najvišu prosecnu vrednost koeficijenta determinacije, R2 (0,9989), novi model je pokazao najbolje fitovanje eksperimentalnih podataka, u poreenju sa uobicajeno korišcenim modelima adsorpcije u koloni. RSM i ANN modelovanje je dalje korišceno za evaluaciju procesnih parametara i optimizaciju procesa. Najznacajnija nezavisno promenljiva velicina, koja ispoljava negativan uticaj na odabrani odziv (kriticno vreme), bila je koncentracija napojnog rastvora, dok je masa adsorbenta ispoljila slabiji i pozitivan uticaj na odziv. Optimizacijom procesa metodom ANN je utvreno da se najveca vrednost kriticnog vremena (341,4 min) postiže pri sledecim uslovima: C0=50 mgL-1, ma=12 g and pH 4,53, dok metoda RSM smatra pH vrednost faktorom koji nema znacaja po odziv u ispitivanom opsegu, i postiže maksimalno kriticno vreme od 314,8 min, pri istim ostalim uslovima kao i ANN. Iskorišceni adsorbent, zasicen jonima bakra, je zatim spaljen i dobijeni pepeo je iskorišcen kao punilo u proizvodnji gume. Proizvedena su cetiri uzorka gume sa razlicitim sadržajem pepela. Pracen je proces vulkanizacije gume, odreena su mehanicka svojstva gotovog proizvoda i izvreno je poreenje dobijenih rezultata izmeu uzoraka sa i bez dodatka pepela. Rezultati su pok, The potential use of sugar beet shreds for copper ions removal from aqueous solution in a fixed-bed column was investigated. Experiments were performed using Box-Behnken experimental design on three levels and three variables: concentration of the inlet solution (50-150 mgL-1), adsorbent dosage (8-12 g) and pH of the inlet solution (4.0-5.0). The obtained breakthrough curves were fitted with two common empirical models, Bohart-Adams and dose-response. Observing the asymmetric shape of the breakthrough curves, the new mathematical model was proposed. The new model proposes the breakthrough curve composed of two parts, sum of which gives the asymmetrical S-shaped curve, accurately matching experimental data. Regarding the lowest average SSer (3.610-3) and highest average R2 (0.9989), new model exhibited the best fit comparing to the commonly used models. RSM and ANN modelling were employed for process variables evaluation and optimization. The most influential parameter exhibiting negative influence on target response (critical time) was concentration of the inlet solution, while the adsorbent dosage exhibited positive influence. Optimization procedure revealed that the highest critical time (341.4 min) was achieved at following conditions: C0=50 mgL-1, ma=12 g and pH 4.53 by ANN, while RSM considered pH as insignificant factor and obtained 314.8 min as the highest response. Discarded adsorbent, saturated with copper ions, was then incinerated and the obtained ash was used as a rubber filler. Four rubber samples containing different amounts of added ash were produced. The vulcanization process was monitored and mechanical properties was measured and compared with the samples with no ash added. The results revealed that addition of ash has no significant effect on the rubber mechanical properties. However, as the ash content increases, the activation energy of the vulcanization process increases too, which can be considered as an improvement in the cases of large-dimen

U ovoj doktorskoj disertaciji je ispitan uticaj montmorilonita i termoplastičnih segmentiranih poliuretana na kinetiku reakcija umrežavanja, strukturu i svojstva funkcionalnih hibridnih materijala na osnovu epoksidnih smola. Pripremljene su dve serije uzoraka hibridnih materijala: prva na osnovu epoksidne smole sa različitim sadržajem organski modifikovanog montmorilonita (0, 1, 3, 5 i 10 mas.%) umrežene sa umreživačem Jeffamine D-230; druga serija je sintetisana na osnovu epoksidne smole, sa različitim sadržajem (10, 15 i 20 mas.%) termoplastičnog poliuretanskog elastomera sa različitim sadržajem tvrdih segmenata (20, 25 i 30 mas.%) sintetisanih na osnovu alifatičnog polikarbonatnog diola i heksametilendiizocijanata i produživača lanca butandiola, kao i katalizatora dibutiltin dilaurata; kao i bez dodatog elastomera umrežene sa diaminom Jeffamine D-2000. Umrežavanje reaktivnih sistema sa projektovanim sirovinskim sastavom je praćeno diferencijalnom skenirajućom kalorimetrijom (DSC). Modeli izokonverzije primenjeni su da se ustanovi da li dodatak punila utiče na reakciju umrežavanja hibridnih materijala. Sintetisani materijali su analizirani dinamičkomehaničkom analizom (DMA), mikroskopijom atomskih sila (AFM), kao i TG-DSC i TG-MS metodama i određena su mehanička svojstva (zatezna čvrstoća, prekidno izduženje i tvrdoća po Šoru A). Epoksidni materijal sa 10 mas.% organski modifikovanog montmorilonita ima značajno niže vrednosti energija aktivacije za definisane stepene reagovanja, čime je potvrđen katalitički efekat gline sa slojevitom strukturom kada je prisutna u reakcionoj smeši u dovoljnoj količini. Uticaj otežane difuzije pri kraju reakcije je izraženiji u prisustvu montmorilonita, čime je pokazano da njegovo prisustvo utiče na ceo mehanizam umrežavanja. Utvrđeno je da na vrednosti G', pored udela montmorilonita, utiče i stepen dispergovanja čestica unutar polimerne matrice. Zaključeno je da dodatak punila do 3 mas. % utiče povoljno na ispitana mehanička svojst, In this thesis the influence of clay fillers and thermoplastic segmented polyurethanes on the curing kinetics, structure and properties of functional hybrid materials based on epoxy resins was assessed. Two sets of hybrid material samples were prepared. First type of samples was based on epoxy resin with a different content of organically modified montmorillonite (0, 1, 3, 5 and 10 wt. %) and crosslinking with hardener Jeffamine D-230. Second type of samples was based on epoxy resin, having different content (10, 15 and 20 wt. %) of thermoplastic segmented polyurethane with different content of hard segments (20, 25 and 30 wt. %) based on aliphatic polycarbonate macrodiols and hexamethylene diisocyanate, with chain extender 1,4-butanediol and the catalyst, dibutyltin dilaurate, and also a sample without added elastomeric polyurethane and crosslinking with hardener Jeffamine D- 2000. The curing of the hybrid materials based on epoxy resins systems were investigated by non-isothermal differential scanning calorimetry (DSC). The kinetic study by isoconversion models has been carried out using data from DSC. The synthesized materials were analyzed by dynamicmechanical analysis (DMA), atomic force microscopy (AFM) as well as TG-DSC and TG-MS methods and mechanical properties (tensile strength, elongation and hardness at Shore A) were determined. Epoxy based hybrid material with 10 wt. % of the organically modified montmorillonite has significantly lower activation energy values for the defined reaction rates, thereby confirming the catalytic effect of the clay with the layered structure when present in the reaction mixture in sufficient quantity. The diffusion effects at the end of the reaction are more pronounced in the presence of montmorillonite, which indicates that its presence affects the entire curing mechanism. It was found that G', along with montmorillonite content, is affected by the degree of particle dispersion inside the polymer matrix. It was concluded tha