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The synthesis of fatty acid methyl esters (FAME), i.e. biodiesel, in the methanolysis of triglycerides (TG) in the presence of solid catalyst was studied. Heterogeneous catalyst was synthesized by mechanochemical treatment of CaO and ZnO powder mixture with the addition of water required for the formation of corresponding mixed hydroxides, CaZn2(OH)6·2H2O, followed by calcination at 700 °C in air to obtain CaO∙ZnO composite powder. After detailed characterization CaO∙ZnO catalyst was used in methanolysis of refined sunflower as well as used vegetable oil (UVO) in the batch conditions. Influence of temperature, agitation speed, catalyst amount and methanol to oil molar ratio on the rate of reaction was analyzed in order to determine parameters that completely define the rate of methanolysis and indicate the basic resistances on which it depends. It was revealed that the rate of the process depends on the two resistances – mass transfer of triglycerides to the catalyst surface and chemical reaction on the catalyst surface, which are defined as reciprocal value of , the overall triglyceride volumetric mass transfer coefficient and , the effective pseudo-first order reaction rate constant. These kinetic parameters actually determine the value of the apparent reaction rate constant, , which changes with the progression of the methanolysis process, i.e. with the change of triglyceride conversion. The rate of the process is thus described with the simple kinetic model of irreversible pseudo-first order reaction with the variable apparent rate constant, which takes into account both the triglycerides mass transfer and chemical reaction between TG and methanol. The overall volumetric mass transfer coefficient, , was found to depend on interfacial area between the oil and methanol, and can be presented as the function of TG conversion. This assumption is based on the observed effect that when critical conversion of TG is achieved, after formation of small amounts of MG, DG and FAME, the mass transfer rate starts to be higher than the rate of chemical reaction on the catalyst surface. Then the chemical reaction starts to control the overall process rate... U ovoj disertaciji ispitivana je sinteza metil estara masnih kiselina (MEMK), odnosno biodizela u reakciji metanolize triglicerida (TG) u prisustvu čvrstog katalizatora. Sinteza katalizatora izvršena je mehanohemijskim putem polazeći od CaO i ZnO prahova uz dodatak vode, kako bi se dobio prekursor CaZn2(OH)6·2H2O, koji se ţarenjem na 700 °C prevodi u smešu oksida CaO∙ZnO. Nakon detaljne karakterizacije, CaO∙ZnO katalizator korišćen je u reakciji metanolize rafinisanog suncokretovog i korišćenog biljnog ulja (KBU) koja je izvedena u šarţnim uslovima. U cilju odreĎivanja parametara koji u potpunosti definišu brzinu metanolize i ukazuju na osnovne otpore od kojih ona zavisi, analiziran je uticaj temperature, molarnog odnosa metanol:ulje, mase katalizatora i intenziteta mešanja na brzinu procesa. UtvrĎeno je da brzina procesa zavisi od otpora prenosu mase TG do površine katalizatora i otpora hemijskoj reakciji na površini katalizatora, koji su definisani kao recipročna vrednost ukupnog zapreminskog koeficijenta prenosa mase, , i konstante brzine reakcije pseudo prvog reda, . Ovi kinetički parametri odreĎuju vrednost prividne konstante brzine koja se menja sa napredovanjem procesa metanolize, odnosno sa promenom stepena konverzije TG. Brzina procesa je na taj način opisana kinetičkim modelom nepovratne reakcije prvog reda sa promenljivom prividnom konstantom brzine koja uzima u obzir i prenos mase TG i brzinu hemijske reakcije izmeĎu TG i metanola. UtvrĎeno je da ukupan zapreminski koeficijent prenosa mase, , zavisi od specifične meĎufazne površine, kao i da se moţe predstaviti kao funkcija stepena konverzije TG. Ova pretpostavka se bazira na uočenom efektu da se dostizanjem odreĎene kritične konverzije TG nakon stvaranja prvih količina monoglicerida (MG), diglicerida (DG) i MEMK, brzina prenosa mase znatnije uvećava i postaje veća od brzine hemijske reakcije na površini katalizatora. Tada reakcija na površini katalizatora počinje da kontroliše brzinu ukupnog procesa...

Glavni problem za širu primenu metil estara masnih kiselina (biodizela) je njihova visoka cena proizvodnje. Proizvodna cena biodizela bi mogla da se smanji kako smanjenjem cene sirovina (biljnih ulja, životinjskih masti, korišćenih ulja) tako i primenom efikasnijih tehnologija za njegovu proizvodnju. Da bi se tehnologija sinteze biodizela, koja se danas najviše primenjuje u industrijskim uslovima, poboljšala ili eventualno predložila nova, neophodno je da se sam reakcioni sistem jasno definiše. U ovom radu je analizirana sinteza u natkritičnim uslovima, definisana fazna ravnoteža sistema triglicerida i metanola, kao i njihovih proizvoda, metil estara, diglicerida, monoglicerida i glicerola. Metodom doprinosa grupa izračunati su kritični parametri i na osnovu eksperimentalnih podataka rastvorljivosti triglicerida u metanolu u natkritičnim uslovima i njihovom regresijom na više temperature i pritiske, definisan je termodinamički model, koji najbolje opisuje ponašanje analiziranog sistema. Simulacijom u programskom paketu ASPENplus analizirano je ponašanje ovako kompleksnog sistema, ravnoteža i broj faza tokom reakcije metanolize. U zavisnosti od reakcionih uslova, pritiska i temperature, kao i molskog odnosa metanol – ulje, predloženi su kinetički modeli i određeni kinetički parametri reakcije metanolize triglicerida u subkritičnim i natkritičnim uslovima. Ovako definisani kinetički modeli su potvrdili postojanje promene faza, odnosno broja faza u reakcionom sistemu u zavisnosti od temperature i pritiska. Sa definisanim termodinamičkim parametrima i kinetičkim modelom, izvršena je simulacija procesa natkritične proizvodnje biodizela i ovaj postupak sinteze upoređen sa homogeno katalizovanom metanolizom triglicerida. Dobijeni rezultati ukazuju da je proizvodnja biodizela u natkritičnim uslovima konkurentna i realno primenljiva u industrijskim uslovima. Na osnovu detaljne analize i simulacije procesa ukazani su nedostaci postojeće klasične tehnologije zasnovane na primeni alkalnog katalizatora. Takođe, ukazano je da če se buduća industrijska proizvodnja biodizela zasnivati na primeni heterogenog katalizatora. The main obstacle for wider application of biodiesel is its relatively high cost. This is still the truth, although the price gap between petroleum based diesel fuel and biodiesel is narrowing due to the recent increase of crude oil prices. The overall cost of biodiesel fuel could be reduced either by the reduction of raw material cost (vegetable oil, animal fat, used vegetable oil) or by the application of more efficient processing technology. For the further development of biodiesel production technology or application of some advance and new technology, it is necessary clearly defined the reaction system. In this study it was detailed defined the phase equilibria for the system triglycerides and methanol as well as for their products (methyl esters, diglycerides, monoglycerides and glycerol). It was calculated the new value for the critical parameters based on group contribution method. Regression of experimental data for solubility of triglycerides in methanol in subcritical conditions and simulation to higher temperature and pressure, it was define the thermodynamic model which truly describe such system (RK-Aspen equation of state). Simulation with ASPENplus software it was defined the behavior of such complex system during the reaction of methanolysis of triglycerides. The phase content and phase transition was clearly described, also. Kinetic model and kinetic parameters of methanolysis reaction in subcritical and supercritical conditions are proposed in dependenc of temperature and pressure and methanol to oil molar ratio. Such defined the kinetic model was matched and have explanation with the phase equilibria of analyzed system (the number of phases for subcritical and supercritical conditions for reaction). Furthermore, with defined therodinamic and kinetic data, it was performed the process design for the supercritical production of biodiesel. The obtained results are comperd with design’s data for the clasicaly production of biodiesel (alkali homgenious catalysed reaction). There are compared by process parameter and process unit as well as by energy consumption. The obtained result of such analyses showed that biodiesel production at supercritical methanol represents the competitive technology for biodiesel production, and not only competitive with classical one (homogeneous alkali catalysed alcoholysis) but even less energetic required, what have influence on biodiesel price. Based on this design it was pointed the unsufficiences of classic biodiesel technologu as well as their solutions. The end of this study is focused on determination the best route for reducing the energy consumption in biodiesel production at supercritical condition. It was shown that future technology must be mainly based on use of heterogeneous catalyst at moderate pressure and temperature as well as at optimal molar ratio of methanol and oil.

Cilj ove doktorske disertacije je postavljanjematematičkog modela složenog trofaznog reakcionogsistem za epoksidovanje sojinog ulja in situ formiranompersirćetnom kiselinom iz sirćetne kiseline i vodonikperoksida u prisustvu jonoizmenjivačke smole kaokatalizatora. Model uzima u obzir koncentracijereaktanata i produkata u vodenoj i uljnoj fazi. Poredosnovnih reakcija stvaranja persirćetne kiseline iepoksida, model obuhvata i sporednu reakciju otvaranjaepoksi prstena sa sirćetnom kiselinom. Za modelovanjereakcije formiranja persirćetne kiseline na površinikatalizatora primenjeni su Langmuir-Hinshelwood-Hougen-Watson i Rideal-Eley postulati. Postavljenitrofazni model predstavlja sistem običnih diferencijalnihjednačina prvog reda koji opisuje promenu broja molovakomponenata i funkcionalnih grupa sa vremenomizvođenja procesa epoksidovanja, i sadrži više parametararazvrstanih na kinetičke, termodinamičke i parametre kojise odnose na prenos mase. Parametri modela zavise oduslova izvođenja epoksidovanja i to svi od temperature, aneki i od sastava i inteziteta mešanja.Za konstantu hemijske ravnoteže reakcije nastajanjapersirćetne kiseline je izvedena semiteorijska zavisnostod temperature koja daje vrednosti istog reda veličine iistog smera promene sa temperaturom kao i većinapodataka objavljenih u literaturi.Za izračunavanje koeficijenta raspodele sirćetne kiselineizmeđu uljne i vodene faze potrebno je odrediti zavisnostkonstante fazne ravnoteže tečno-tečno sirćetne kiseline odsastava i temperature. Utvrđeno je da je UNIFAC modelgrupnih doprinosa za koeficijente aktivnosti nepogodanza predskazivanje ravnoteže tečno-tečno. Eksperimentalnipodaci za ovu konstantu ravnoteže su uspešno korelisaniUNIQUAC modelom za koeficijente aktivnosti.Parametri reparametrizovane Arrheniusove zavisnostikonstanti brzina reakcija i konstanti sorpcije učesnikareakcije stvaranja persirćetne kiseline od temperatureodređeni su simultano sa parametrima koji se odnose naprenos mase i sa odnosom koeficijenata raspodelepersirćetne i sirćetne kiseline između uljne i vodene faze,fitovanjem eksperimentalnih podataka epoksidovanjasojinog ulja, tj. minimizacijom sume kvadrata odstupanjaračunskih od eksperimentalno određenih vrednosti jodnogbroja i sadržaja epoksi kiseonika tokom epoksidovanja.Fitovanje je uspešno izvedeno primenom metodeMarquardta, dok su pomenute računske vrednostidobijene numeričkom integracijom sistemadiferencijalnih jednačina modela primenom Runge-Kuttametode IV reda., The objective of this doctoral thesis was development ofmathematical model for complex three-phase reactionsystem for soybean oil epoxidation with peracetic acidformed in situ from acetic acid and hydrogen peroxide in apresence of an ion exchange resin as catalyst. The localconcentrations of components in water and oil phases wereintroduced into the model. In addition to reactions of theperacetic acid and epoxy compound formation, modelconsiders the side reaction of epoxy ring cleavage withacetic acid. Approximate modeling of peracetic acidformation was based on Langmuir-Hinshelwood-Hougen-Watson and Rideal-Eley postulates. Established threephasemodel is a system of ordinary first order differentialequations which describes change of components andfunctional groups amounts with reaction time. Besideskinetic parameters, model comprises the thermodynamicones as well as parameters of mass transfer between the oiland water phase. All model parameters are dependent ontemperature and some additionally on composition andintensity of stirring.A semitheoretical temperature dependency of chemicalequilibrium constant for peracetic acid formation wasestablished. The order of magnitude and temperature trendof the calculated chemical equilibrium constant are inagreement with the most data given in a literature.For calculation of partition coefficient for acetic acidbetween oil and water phase, temperature and compositiondependency of liquid-liquid equilibrium constant for aceticacid is necessary. It was found that UNIFAC model ofgroup contribution was non-applicable for the predictionof the equilibrium constant. The experimental data for theequilibrium constant were, however, successfully fitted byUNIQUAC model.Temperature dependencies of the reaction rate constantsand sorption constants of reactants and products inperacetic acid formation reaction are expressed byreparameterized Arrhenius equation. The parameters ofsuch equation were determined simultaneously with masstransfer parameters and ratio of peracetic acid and aceticacid partition coefficients between oil and water phase byfitting the experimental data i.e. by minimization of leastsum of squares of deviation between the calculated andexperimentally determined iodine value and epoxy oxygencontent . Marquardt method was successfully used to fitthe experimental data. A fourth-ordered Runge-Kuttamethod was applied for integrating the system ofdifferential equations of the model.

U ovoj doktorskoj disertaciji ispitivani su kinetika hidrodestilacije, prinos, sastav i frakcionisanje etarskog ulja ploda kleke (Juniperus communis L.) ubrane na Šar planini, Mokroj gori, Rogozni i Kopaoniku. Određeni su prinos, sastav i fizičko-hemijske osobine etarskih ulja i razvijen dvoparametarski model kinetike hidrodestilacije etarskog ulja iz ploda kleke. Model je zasnovan na pretpostavci da se u početnoj fazi etarsko ulje sa površine čestica biljnog materijala, ili blizu nje, brzo „ispira“ („brza“ hidrodestilacija), iza koje sledi difuzija etarskog ulja iz unutašnjosti čestica biljnog materijala prema njihovoj spoljnoj površini („spora“ hidrodestilacija). Pokazano je vrlo dobro slaganje razvijenog modela sa eksperimentalnim podacima u fazi „spore“ hidrodestilacije, kao i odstupanje u fazi „brze“ hidrodestilacije. Model je potvrđen u slučaju hidrodestilacije etarskog ulja ne samo ploda kleke, već i drugih biljnih vrsta. Razvijeni dvoparametarski model se podudara sa troparametarskim fenomenološkim modelom u fazi „spore“ hidrodestilacije, za razliku od jednoparametarskih modela zasnovanih na nestacionarnoj difuziji i kinetici prvog reda, koji nisu pogodni za opisivanje kinetike hidrodestilacije etarskog ulja ploda kleke. U cilju praćenja promene sastava etarskog ulja u toku hidrodestilacije izdvojene su frakcije i GC-MS analizom ispitan njihov sastav. Utvrđeno je da se sastav etarskog ulja značajno menja u toku procesa. U prvim frakcijama dominiraju lako isparljive komponente: α-pinen, sabinen, mircen i limonen, a u frakcijama na kraju teško isparljive: izokariofilen, humulen, germakren D i germakren B. Zbog neuporedivo veće vrednosti komponenata i njihovih frakcija od etarskog ulja, proces frakcionisanja je izveden u toku hidrodestilacije sa ugrađenom rektifikacionom kolonom od 36 teorijskih podova. Istovremenom hidrodestilacijom i rektifikacijom dobijene su dve frakcije: prva, u kojoj dominiraju lako isparljive komponente od α-pinena do 1-terpinen-4-ola i druga, koja pretežno sadrži teško isparljive komponente: izokariofilen, humulen, germakren D i germakren B. Etarsko ulje dobijeno hidrodestilacijom, separacijom je razdvojeno u više frakcija šaržnom rektifikacijom u vakuumu u koloni sa 36 teorijskih podova (8 kPa, odnosno 60 mm Hg; i 3,4 kPa, odnosno 25 mm Hg). Izdvojene su frakcije sa čistim α-pinenom (>99,8 %) kao i frakcije u kojima dominiraju α-pinen, sabinen, mircen i limonen. Etarsko ulje i karakteristične frakcije sa čistim α-pinenom, i α-pinenom i sabinenom pokazale su antimikrobne aktivnosti na neke vrste bakterija, gljiva i plesni. Najširu zonu inhibicije pokazala je frakcija sa čistim α-pinenom, a najužu etarsko ulje. Proces šaržne vakuum rektifikacije etarskog ulja kleke je analiziran i definisan korišćenjem programskog paketa ASPEN Plus. Proračun koncentracija lako isparljivih komponenata (α-pinen, sabinen, mircen i limonen) u frakcijama izvršen je na osnovu predviđanja napona para tih komponenata preko Antoine-ove jednačine. Pokazalo se vrlo dobro slaganje proračunatih i eksperimentalno dobijenih koncentracija, kao i procesnih parametara, kao što su tokovi u koloni i refluksni odnos. Takođe, proračunom pri različitim refluksnim odnosima, određena je potrošnja energije pri šaržnoj vakuum rektifikaciji na osnovu koje je napravljena procena da za optimalnu separaciju etarskog ulja treba koristiti kolonu od 25 teorijskih podova pri refluksnom odnosu 7 ili većem. The kinetics of hydrodistillation, as well as the yield, the composition, the physico-chemical properties and the fractionation of essential oil from juniper (Juniperus communis L.) berries collected at the Šara, Mokra gora, Rogozna and Kopaonik montains were studied. The yield, the composition and the physico-chemical properties of the essential oils were determined. A two parameter model of the essential oil hydrodistillation kinetics was developed, which was based on the assumption that in the initial process stage, the essential oil from the exteranal surface of plant berries, or close to it, was „washed out“ very fast („fast“ hydrodistillation) followed by the diffusion of essential oil through berries toward the external surface („slow“ hydrodistillation). A good agreement between the model and the experimental data was found only in the stage of „slow“ hydrodistillation. The model was also proved for the hydrodistillation of essential oils from different parts of various plants. Derived model was shown to fit very well the experimental data during the whole hydrodistillation process, while the simpler one-parameter models based on the unsteady-state diffusion and the first-order kinetics were not applicable. Several fractions of an essential oil were collected during the hydrodistillation process and their compostion was determined by GC-MS. The first fractions contained mainly easily-volatile constituents such as α-pinene, sabinene, myrcene and limonene, while the fractions collected during the final phase of the hydrodistillation contained heavily-volatile components such as isocaryophyllene, humulene, germacrene D and germacrene B. To get the compounds and the fractions more valuable than the original essential oil, hydrodistiilation and fractionation were simultaneously carried out using rectification column having 36 theoretical plates. By this, so called simultaneous hydrodistiilation and rectification, two fractions were obtained: one having easily-volatile compounds (from α-pinene to 1-terpinee-4-ol), and the other containing heavily-volatile compounds (isocaryophyllene, humulene, germacrene D i germacrene B). The essential oil obtained by classical hydrodistillation was fractionated in the rectification column with 36 theoretical plates under vacuum (8 kPa or 60 mm Hg; and, 3,4 kPa or 25 mm Hg). In this way, the fractions containing pure α-pinene (>99.8 %) and the fractions rich in α-pinene, sabinene, myrcene and limonene were obtained. The essential oil and the characteristic fractions showed antimicrobial activity against some bacteria, yeast and fungi, the most active being the fraction containing pure α-pinene. The process of batch rectification of the essential oil under vacuum was simulated using the ASPEN Plus softwere package. The concentrations of easily volatile constituents (α-pinene, sabinene, myrcene and limonene) in the fractions were calculated using the Antoin’s equation to estimate the vapor pressure of individual components. A good agreement between the calculated and experimental concentrations as well as the process parameters such as flow rates through the column and the reflux ratio were shown. Also, the energy consumption in the vacuum rectification process was calculated at different reflux ratios. Based on these data, it was determined that the optimum column should have 25 theoretical plates and should operate at the reflux ratio of 7 or higher for desired separation of essential oil.

Tema ove doktorske disertacije je ispitivanje bubrenja biljnog materijala pod uticajem natkritičnog ugljenik(IV)-oksida, kao i efekata koje bubrenje ima na proces natkritične ekstrakcije (NKE). Na rezultate eksperimenata u kojima je praćena kinetika procesa NKE primenjen je matematički model na nivou sekrecione strukture i model Sovove, kako bi se promene do kojih dolazi usled bubrenja biljnog materijala kvantitativno izrazile preko parametara modela. Ispitano je bubrenje glandularnih trihoma biljaka familije Lamiaceae, bubrenje hmelja u vidu mlevenih čestica biljnog materijala i industrijskih granulata, i bubrenje čestica korena odoljena i rizoma đumbira. Ispitivanja su vođena u pravcu optimizacije procesa NKE u odnosu na potrošnju natkritičnog fluida i energije. Za proces NKE etarskih ulja iz glandularnih trihoma razvijen je kompleksan matematički model koji uključuje raspodelu vremena pucanja glandularnih trihoma, koji opisuje proces NKE sa znatno većom tačnošću u odnosu na postojeće matematičke modele. Za ekstrakciju na višim pritiscima definisan je optimalan predtretman biljnog materijala kojim se postižu značajne uštede natkritičnog fluida. U slučaju bubrenja hmelja razmatrani su fenomeni prenosa mase u šišaricama i granulatima hmelja izloženim natkritičnom fluidu na različitim uslovima. Rezultati su objasnili pojave koje se dešavaju na industrijskom nivou, a pre svega nepoželjno očvršćavanje ekstrakcione pogače. Parametri procesa (koeficijenti difuzije kroz čvrstu fazu) opisani su primenom matematičkih modela na eksperimentalne rezultate. U slučaju bubrenja korena odoljena i rizoma đumbira, izborom optimalnog predtretmana ostvarene su značajne uštede natkritičnog fluida. Parametri procesa (koeficijenti prenosa mase kroz čvrstu fazu) opisani su primenom matematičkih modela na eksperimentaln rezultate. The subject of this disertation is the swelling of plant material under the influence of supercritical carbon dioxide, as well as the effects of swelling on the process of supercritical fluid extraction (SFE). The results of experiments on the kinetics of the SFE processes were modeled using a mathematical model on the micro-scale and the Sovova’s model, which quantitatively express, through the parameters of the model, the changes that occur due to the swelling of plant material. The swelling of glandular trichomes of plants of the Lamiaceae family, swelling of hop in the form of ground particles of plant material and industrial granulates, and swelling of the particles of valerian root and rhizome of ginger were observed. The tests were conducted in order to examine the possibility of optimization the SFE process in respect to the consumption of supercritical fluids and energy. For the process of SFE of essential oils from glandular trichomes, a complex mathematical model which includes the cracking time distribution for glandular trichomes was developed. The new model describes the process of SFE with significantly higher accuracy than the existing mathematical models. For extraction at higher pressures the optimal pretreatment of plant material is defined with the goal to achieve significant savings of supercritical fluid. In the case of swelling of hops, the mass transport phenomena in granulates and cones exposed to supercritical fluid in various conditions were considered. The results explained phenomena that occur on industrial scale, especially undesirable hardening of the extraction cake. Process parameters (diffusion coefficients in the solid phase) are described by applying mathematical models to experimental results. In the case of swelling of valerian root and rhizome of ginger, significant savings of supercritical fluid consumption were achieved by choosing the optimal treatment. Process parameters (coefficients of mass transfer through the solid phase) are described by applying mathematical models to experimental results.

Cilј оvоg rаdа biо је оdrеđivаnjе аntiоksidаtivnе аktivnоsti frаkciја ruzmаrinа (Rosmarinus officinalis), žаlfiје (Salvia officinalis), timiјаnа (Thymus vulgaris) i izоpа (Hyssop officinalis), kао i hеmiјskа аnаlizа izоlоvаnih frаkciја. Аntiоksidаtivnе frаkciје su izоlоvаnе primеnоm frаkciоnе еkstrаkciје sа nаtkritičnim uglјеnik(IV)-оksidоm nа pritisku оd 35 MPa i tеmpеrаturi оd 100°C. Zа оdrеđivаnjе аntiоksidаtivnе аktivnоsti izоlоvаnih frаkciја primеnjivаnа је еlеktrоn spin rеzоnаntnа (ESR) spеktrоskоpiја. Dеfinisаnjе аntiоksidаtivnе аktivnоsti dаtih frаkciја vršilо sе mеrеnjеm njihоvе spоsоbnоsti dа "hvаtајu" 1,1-difеnil-2-pikrilhidrаzil rаdikаlе (DPPH) i hidrоksil rаdikаlе. Оdrеđivаnjе spоsоbnоsti аntiоksidаtivnih frаkciја dа inhibirајu lipidnu pеrоksidаciјu vršilо sе mеrеnjеm pеrоksidnоg brоја u suncоkrеtоvоm ulјu prеmа stаndаrdnоm pоstupku ISO 3960:1977. Аntiоksidаtivnа аktivnоst еkstrаkаtа upоrеđivаnа је sа аktivnоšću butilоvаnоg hidrоksiаnizоlа (BHA) i kоmеrciјаlnоg ruzmаrinskоg еkstrаktа Flavor' Plus™. Hеmiјskа аnаlizа pоmоću HPLC-DAD/ESI-ToF-MS bilа је usmеrеnа nа kvаntitаtivnо оdrеđivаnjе kаrnоsоlа i kаrnоsоlnе kisеlinе, kојi prеdstаvlјајu јеdinjеnjа zа kоја sе vеruје dа pоsеduјu nајvеću аntiоksidаtivnu аktivnоst u ispitivаnim frаkciјаmа. U tоm cilјu kоristili su sе čisti stаndаrdi оvih јеdinjеnjа dоk је idеntifikаciја оstаlih јеdinjеnjа bilа tеntаtivnа. Nа оsnоvu DPPH rаdikаl mеtоdе rеdоslеd оd nајјаčе dо nајslаbiје аntiоksidаtivnе аktivnоsti biо је: BHA, еkstrаkt timiјаnа, Flavor' Plus™, ekstrakt ruzmarina, ekstrakt žalfije i ekstrakt izopa, dok je pri hidroksil radikal metodi redosled bio: Flavor' Plus™, еkstrаkt žаlfiје, еkstrаkt ruzmаrinа, еkstrаkt izоpа, BHA i еkstrаkt timiјаnа. Svi ispitivаni еkstrаkti pоkаzаli su sе kао inhibitоri lipidnе pеrоksidаciје suncоkrеtоvоg ulја. Nајbоlјu аntiоksidаtivnu аktivnоst mеđu ispitivаnim еkstrаktimа pоkаzао је еkstrаkt ruzmаrinа. Nа оsnоvu vrеdnоsti pеrоksidnоg brоја аntiоksidаtivnа аktivnоst ispitivаnih bilјnih еkstrаkаtа pоslе 12 h čuvаnjа nа 98°C bila је slеdеćа: еkstrаkt ruzmаrinа > BHA > еkstrаkt žаlfiје > Flavor' Plus™ > еkstrаkt timiјаnа > еkstrаkt izоpа. Rеzultаti su pоkаzаli dа аntiоksidаtivnе frаkciје iz ruzmаrinа i žаlfiје imајu nајvеći sаdržај fеnоlnih ditеrpеnа i dа prеdstаvlјајu vаžаn izvоr zа prоizvоdnju i primеnu u prеhrаmbеnој industriјi nutritivnih suplеmеnаtа, kоmpоnеnаtа funkciоnаlnе hrаnе ili аntiоksidаnаsа. The aim of the present work was to determine the antioxidatnt activity of fractions from rosemary (Rosmarinus officinalis), sage (Salvia officinalis), thyme (Thymus vulgaris) and hyssop (Hyssop officinalis), and chemical analysis of obtained fractions. In order to isolate antioxidant fractions method of fractional supercritical extraction with carbon dioxide at 35 MPa and 100°C was applied. Antioxidant activity of obtained extracts was determined by measuring their ability to scavenge 1,1-diphenyl-2-picrylhydrazyl (DPPH) free radical and hydroxyl radical using electron spin resonance (ESR) spectroscopy. The protective effect of added SFE extracts on the oxidative stability of sunflower oil was followed by determination of its peroxide value (PV) by the official method ISO 3960:1977 during storage at 98°C. The antioxidant activity of the extracts was compared to the activity of butylated hydroxyanisole (BHA) and commercial rosemary extract Flavor' Plus™. Chemical analysis of obtained antioxidant extracts was performed using HPLC-DAD/ESI-ToF-MS. Carnosol and carnosic acid, among the main antioxidant compounds present in examinated extracts, were quantified with regard to pure standard. Identification of the other compounds was tentative. It was shown that in DPPH radical assay the order from the strongest to the weakest antioxidant activity was: BHA, thyme extract, Flavor' Plus™, rosemary and sage extracts, and hyssop extract, while in hydroxyl radical assay order was: Flavor' Plus™, sage extract, rosemary extract, hyssop extract, BHA and thyme extract. All investigating extracts were effective on retarding lipid oxidation of sunflower oil. Among them, rosemary extract exhibited the best antioxidative activity. On the basis of peroxide value assay, antioxidant activity of the investigated plant extracts after 12 h of storage at 98°C followed the order: rosemary extract > BHA > sage extract > Flavor' Plus™ > thyme extract > hyssop extract. Results of the present study demonstrate the positive effects of adding antioxidant fractions from rosemary and sage on retarding lipid oxidation of sunflower oil. This investigation showed that antioxidant fraction from rosemary and sage had the highest amounts of phenolic diterpenes, indicating their potential use in food industry as nutritional supplements, functional food components or food antioxidants.

The subject of this disertation is the swelling of plant material under the influence of supercritical carbon dioxide, as well as the effects of swelling on the process of supercritical fluid extraction (SFE). The results of experiments on the kinetics of the SFE processes were modeled using a mathematical model on the micro-scale and the Sovova’s model, which quantitatively express, through the parameters of the model, the changes that occur due to the swelling of plant material. The swelling of glandular trichomes of plants of the Lamiaceae family, swelling of hop in the form of ground particles of plant material and industrial granulates, and swelling of the particles of valerian root and rhizome of ginger were observed. The tests were conducted in order to examine the possibility of optimization the SFE process in respect to the consumption of supercritical fluids and energy. For the process of SFE of essential oils from glandular trichomes, a complex mathematical model which includes the cracking time distribution for glandular trichomes was developed. The new model describes the process of SFE with significantly higher accuracy than the existing mathematical models. For extraction at higher pressures the optimal pretreatment of plant material is defined with the goal to achieve significant savings of supercritical fluid. In the case of swelling of hops, the mass transport phenomena in granulates and cones exposed to supercritical fluid in various conditions were considered. The results explained phenomena that occur on industrial scale, especially undesirable hardening of the extraction cake. Process parameters (diffusion coefficients in the solid phase) are described by applying mathematical models to experimental results. In the case of swelling of valerian root and rhizome of ginger, significant savings of supercritical fluid consumption were achieved by choosing the optimal treatment. Process parameters (coefficients of mass transfer through the solid phase) are described by applying mathematical models to experimental results. Tema ove doktorske disertacije je ispitivanje bubrenja biljnog materijala pod uticajem natkritičnog ugljenik(IV)-oksida, kao i efekata koje bubrenje ima na proces natkritične ekstrakcije (NKE). Na rezultate eksperimenata u kojima je praćena kinetika procesa NKE primenjen je matematički model na nivou sekrecione strukture i model Sovove, kako bi se promene do kojih dolazi usled bubrenja biljnog materijala kvantitativno izrazile preko parametara modela. Ispitano je bubrenje glandularnih trihoma biljaka familije Lamiaceae, bubrenje hmelja u vidu mlevenih čestica biljnog materijala i industrijskih granulata, i bubrenje čestica korena odoljena i rizoma đumbira. Ispitivanja su vođena u pravcu optimizacije procesa NKE u odnosu na potrošnju natkritičnog fluida i energije. Za proces NKE etarskih ulja iz glandularnih trihoma razvijen je kompleksan matematički model koji uključuje raspodelu vremena pucanja glandularnih trihoma, koji opisuje proces NKE sa znatno većom tačnošću u odnosu na postojeće matematičke modele. Za ekstrakciju na višim pritiscima definisan je optimalan predtretman biljnog materijala kojim se postižu značajne uštede natkritičnog fluida. U slučaju bubrenja hmelja razmatrani su fenomeni prenosa mase u šišaricama i granulatima hmelja izloženim natkritičnom fluidu na različitim uslovima. Rezultati su objasnili pojave koje se dešavaju na industrijskom nivou, a pre svega nepoželjno očvršćavanje ekstrakcione pogače. Parametri procesa (koeficijenti difuzije kroz čvrstu fazu) opisani su primenom matematičkih modela na eksperimentalne rezultate. U slučaju bubrenja korena odoljena i rizoma đumbira, izborom optimalnog predtretmana ostvarene su značajne uštede natkritičnog fluida. Parametri procesa (koeficijenti prenosa mase kroz čvrstu fazu) opisani su primenom matematičkih modela na eksperimentaln rezultate.

U radu su prikazani eksperimentalni rezultati natkritične ekstrakcije etarskog ulja bobicakleke (Juniperus communis L.) i ulja iz semena uljane tikve golice (Cucurbita pepo L.). Ispitan je uticaj pritiska, temperature, stepena usitnjenosti čestica i protoka natkritičnogugljendioksida na promenu prinosa ulja sa vremenom. U cilju poređenja, usitnjeno seme uljane tikve ekstrahovano je i u ekstraktoru većih dimenzija, NOVA-SWISS, Highpressure extraction plant, kao i heksanom i petroletrom u ekstraktoru tipa Sokslet.Praćena je i promena kvaliteta ekstrakata sa vremenom: u etarskom ulju kleke, GC-FID i GC-MS metodama, određen je relativni sadržaj 50 terpenskih jedinjenja i sve komponente ulja su svrstane u 5 osnovnih grupa (monoterpene, seskviterpene, oksidovane monoterpene, oksidovane seskviterpene i ostale komponente). U tikvinom ulju ekstrahovanom natkritičnim ugljendioksidom određen je masnokiselinski sastav GC-MS analizom, sadržaj tokoferola HPLC analizom, sterola i skvalena GC-MS metodom. Određeni su uslovi koji favorizuju ekstrakciju ispitanih jedinjenja za obe sirovine. Dat je dateljan prikaz matematičkih modela koji se koriste za opisivanje natkritične ekstrakcije etarskih ulja i masnih ulja, počevši od najopštijeg modela koji uključuje diferencijalne bilanse mase za rastvorak u masi natkritičnog fluida, u fluidu unutar pora čestica usitnjenog matrijala i u čvrstoj fazi, koji se uvođenjem određenih pretpostavki pojednostavljuje i svodi na modele koji su izabrani da budu ispitani u okviru ovoga rada. Ispitani su modeli kreireni po analogiji sa hlađenjem vrele kugle u masi fluida, tj. modeli tipa jedne sfere i to: Model jedne sfere-1 (MJS-1), koji pored uticaja koeficijenta efektivne difuzije ulja u materijalu na brzinu prenosa mase uzima u obzir uticaj koeficijenta prenosa mase kroz film natkritičnog fluida oko čestice, pri čemu je njegova vrednost procenjena preko postojećih korelacija; MJS-1 (2 par), u kome je spoljašnji koeficijent prenosa mase uzet kao drugi prilagodljiv parametar modela; MJS-2, gde je koeficijent efektivne difuzije jedini prilagođeni parametar, Model karakterističnog vremena i prošireni model klipnog toka koji je predložila Sovová. Za modelovanje natkritične ekstrakcije ulja semena tikve korišćen je i kombinovani model Honga i sar. Softverskim paketima Mathcad 2001 Professional i Solver dodatka unutar Microsoft Excel 2003, određeni su parametri ispitanih modela u cilju najboljeg slaganja modela sa ekperimentalnim podacima. Za obe ispitane sirovine, među ispitanim modelima, izabrani su modeli koji najbolje opisuju njihovu ekstrakciju natkritičnim ugljendioksidom. Prošireni model klipnog toka koji je predložila Sovová pokazao se podjednako dobrim za modelovanje natkritične ekstrakcije obe sirovine i nešto bolji od ostalih primenjenih modela., This study provides results of supercritical carbon dioxide (SCCO2) extraction of juniper berries (Juniperus communis L.) and pumpkin seeds (Cucurbita pepo L. convar.citrullina) in a laboratorysupercritical fluid extraction apparatus. The influenceof pressure, temperature, particle size and carbon dioxide flow on the extraction kinetics of pumpkin seed oil and juniper berry essential oil was studied. Ground pumpkin seeds were also extracted with supercritical carbon dioxide in NOVA-SWISS, High Pressure Extraction Plant, and with hexane and petroleum ether in a laboratory Soxhlet extractor. This work was also aimed to investigate the evolution of the composition of juniper fruit supercritical CO2 extracts with time, at different extraction pressures and to emphasize the most favorable condition for the extraction of different terpene hydrocarbon groups, reporting the qualitative differences among extracts collected during successive extraction time periods. Juniper berry extracts were analyzed by capillary gas chromatography, using flame ionization (GC-FID) and mass spectrometric detection (GC-MS). More than 200 constituents were detected in the extracts and the contents of 50 compounds were reported in the work. Dependence of the percentage yields of monoterpene, sesquiterpene, oxygenated monoterpene and oxygenated sesquiterpene hydrocarbon groups on extraction time was investigated and conditions that favored the yielding of each terpene groups were emphasized. GC-MS analysis of FAME, prepared by transesterification of pumpkin seed oil with KOH in methanol, was performed. Fatty acid compositions of supercritical CO2 pumpkin seed extract fractions collected in successive time intervals over the course of the extraction were determined. The same fractions were analyzed by high pressure liquid chromatography (HPLC), using diode-array detector (DAD) in order to determine a- and g-tocopherol contents. Sterol and squalene contents were determined by GC-MS analysis, as well. Conditions that favored the yielding of tocopherols, squalene and sterols were emphasized. A general mass transfer model and its simlifications were analysed. Extraction curves were evaluated by “hot sphere” mathematical models SSM-1 (Single Sphere Model 1 – in which the external mass transfer coefficient also influences the extraction profile and film mass transfer coefficients were estimated by the correlations), SSM-1 (2 par) (film mass transfer coefficient is used as the second adjustable parameter), SSM-2 (only effective diffusivity influence is considered), Characteristic time model and by the extended Lack’s plug-flow model given by Sovová. A combined model of Hong et al. was also fitted to the experimental data for pumpkin seed oil SCCO2extractions. Relative merits of the models are demonstrated. Good agreement between the extended Lack’s plug-flow model and the experimental measurements was obtained.

The main obstacle for wider application of biodiesel is its relatively high cost. This is still the truth, although the price gap between petroleum based diesel fuel and biodiesel is narrowing due to the recent increase of crude oil prices. The overall cost of biodiesel fuel could be reduced either by the reduction of raw material cost (vegetable oil, animal fat, used vegetable oil) or by the application of more efficient processing technology. For the further development of biodiesel production technology or application of some advance and new technology, it is necessary clearly defined the reaction system. In this study it was detailed defined the phase equilibria for the system triglycerides and methanol as well as for their products (methyl esters, diglycerides, monoglycerides and glycerol). It was calculated the new value for the critical parameters based on group contribution method. Regression of experimental data for solubility of triglycerides in methanol in subcritical conditions and simulation to higher temperature and pressure, it was define the thermodynamic model which truly describe such system (RK-Aspen equation of state). Simulation with ASPENplus software it was defined the behavior of such complex system during the reaction of methanolysis of triglycerides. The phase content and phase transition was clearly described, also. Kinetic model and kinetic parameters of methanolysis reaction in subcritical and supercritical conditions are proposed in dependenc of temperature and pressure and methanol to oil molar ratio. Such defined the kinetic model was matched and have explanation with the phase equilibria of analyzed system (the number of phases for subcritical and supercritical conditions for reaction). Furthermore, with defined therodinamic and kinetic data, it was performed the process design for the supercritical production of biodiesel. The obtained results are comperd with design’s data for the clasicaly production of biodiesel (alkali homgenious catalysed reaction). There are compared by process parameter and process unit as well as by energy consumption. The obtained result of such analyses showed that biodiesel production at supercritical methanol represents the competitive technology for biodiesel production, and not only competitive with classical one (homogeneous alkali catalysed alcoholysis) but even less energetic required, what have influence on biodiesel price. Based on this design it was pointed the unsufficiences of classic biodiesel technologu as well as their solutions. The end of this study is focused on determination the best route for reducing the energy consumption in biodiesel production at supercritical condition. It was shown that future technology must be mainly based on use of heterogeneous catalyst at moderate pressure and temperature as well as at optimal molar ratio of methanol and oil. Glavni problem za širu primenu metil estara masnih kiselina (biodizela) je njihova visoka cena proizvodnje. Proizvodna cena biodizela bi mogla da se smanji kako smanjenjem cene sirovina (biljnih ulja, životinjskih masti, korišćenih ulja) tako i primenom efikasnijih tehnologija za njegovu proizvodnju. Da bi se tehnologija sinteze biodizela, koja se danas najviše primenjuje u industrijskim uslovima, poboljšala ili eventualno predložila nova, neophodno je da se sam reakcioni sistem jasno definiše. U ovom radu je analizirana sinteza u natkritičnim uslovima, definisana fazna ravnoteža sistema triglicerida i metanola, kao i njihovih proizvoda, metil estara, diglicerida, monoglicerida i glicerola. Metodom doprinosa grupa izračunati su kritični parametri i na osnovu eksperimentalnih podataka rastvorljivosti triglicerida u metanolu u natkritičnim uslovima i njihovom regresijom na više temperature i pritiske, definisan je termodinamički model, koji najbolje opisuje ponašanje analiziranog sistema. Simulacijom u programskom paketu ASPENplus analizirano je ponašanje ovako kompleksnog sistema, ravnoteža i broj faza tokom reakcije metanolize. U zavisnosti od reakcionih uslova, pritiska i temperature, kao i molskog odnosa metanol – ulje, predloženi su kinetički modeli i određeni kinetički parametri reakcije metanolize triglicerida u subkritičnim i natkritičnim uslovima. Ovako definisani kinetički modeli su potvrdili postojanje promene faza, odnosno broja faza u reakcionom sistemu u zavisnosti od temperature i pritiska. Sa definisanim termodinamičkim parametrima i kinetičkim modelom, izvršena je simulacija procesa natkritične proizvodnje biodizela i ovaj postupak sinteze upoređen sa homogeno katalizovanom metanolizom triglicerida. Dobijeni rezultati ukazuju da je proizvodnja biodizela u natkritičnim uslovima konkurentna i realno primenljiva u industrijskim uslovima. Na osnovu detaljne analize i simulacije procesa ukazani su nedostaci postojeće klasične tehnologije zasnovane na primeni alkalnog katalizatora. Takođe, ukazano je da če se buduća industrijska proizvodnja biodizela zasnivati na primeni heterogenog katalizatora.

U ovom radu proučavani su višekomponentni katalitički sistemi u kojima su aktivna komponenta (metalni Ni) i pogodni metali (Mg, Ag i Cu) naneseni na pripremljeni nosač (aktivirani dijatomit), kao i njihova primena u svojstvu katalizatora u procesu parcijalne hidrogenizacije jestivih biljnih ulja. Polazni materijal korišćen za sintezu nosača katalizatora predstavljao je sirovi dijatomit domaćeg porekla (ležište dijatomita Baroševac, istočni deo Kolubarskog ugljenog basena). Modifikacijom svojstava sirovog dijatomita hemijskom i termičkom obradom dobijen je nosač katalizatora sa visokim sadržajem silicijum dioksida. Ispitivanja teksturalnih svojstava i granulometrijskog sastava su pokazala da dijatomitni nosač ima makroporoznu strukturu i povoljan granulometrijski sastav, odgovarajući za dobijanje nikl katalizatora koji se koriste u procesima parcijalne hidrogenizacije biljnih ulja. Izvršena je sinteza nekoliko uzoraka katalizatora precipitacijom jedinjenja nikla i odgovarajućih metala iz vodenih rastvora njihovih nitratnih soli na pripremljeni dijatomitni nosač korišćenjem natrijum karbonata (PDI katalizatori) i uree (DPU katalizatori) u svojstvu precipitanta. Obavljeni su obimni eksperimenti koji su obuhvatili ispitivanja uticaja uslova sinteze prekursora PDI- i DPUNi/ D katalizatora na stepen redukcije. Proučavanjem uticaja SiO2/Ni molskog odnosa i brzine zagrevanja na stepen redukcije prekursora PDI-Ni/D katalizatora utvrđeno je da manji SiO2/Ni m.o. i manje brzine zagrevanja povećavaju stepen redukcije. Ispitivanja uticaja DP vremena na stepen redukcije prekursora DPU-Ni/D katalizatora su pokazala da kraća DP vremena omogućavaju veći stepen redukcije. Fizičko-hemijska svojstva prekursora PDI- i DPU-Ni/D katalizatora okarakterisana su primenom sledećih metoda: (1) standardna kvantitativna hemijska analiza; (2) rendgenostrukturna (XRD) i infracrvena (IR) spektroskopija; (3) Hg-porozimetrija i N2-fizisorpcija; (4) temperaturno-programirana redukcija (TPR); (5) H2-hemisorpcija; (6) skenirajuća elektronska mikroskopija (SEM) i energo disperziona spektroskopija (EDS); (7) difuziono-refleksiona spektroskopija ultravioletne i vidljive oblasti (DR UV-Vis); i (8) fotoelektronska spektroskopija X-zraka (XPS). Rezultati rendgenostrukturnih (XRD) ispitivanja neredukovanih prekursora PDI- i DPU-Ni/D katalizatora su pokazali da se pored Ni2+ faze baznog nikl karbonata (PDI-Ni/D prekursori) i turbostratičnog nikl hidroksida (DPU-Ni/D prekursori) u prekursorima nalaze i Ni hidrosilikati nastali interakcijom aktivnog metala i nosača. Analizom XRD difraktograma redukovano-pasiviziranih prekursora, kao i in situ XRD-H2 difraktograma određene su veličine kristalita aktivnog metalnog nikla i metala modifikatora (Ag). Utvrđeno je da su veličine kristalita nikla manje od veličine kristalita srebra. Rezultati ispitivanja neredukovanih prekursora Ni/D katalizatora infracrvenom spektroskopijom (IR) su potvrdili prisustvo Ni2+ faza baznog karbonata i hidrosilikata i ukazali da je distribucija obrazovane Ni2+ faze više usmerena prema Ni hidrosilikatima nego prema baznom Ni karbonatu (PDI-Ni/D prekursori). Pokazano je da kod DPU-Ni/D prekursora priroda DP Ni2+ faze zavisi od DP vremena. Rezultati ispitivanja porozne strukture neredukovanih prekursora katalizatora metodom Hg-porozimetrije su pokazali da su ukupna intruziona zapremina pora, zapremina makropora, srednji prečnik pora i ukupna poroznost prekursora manji nego kod dijatomitnog nosača usled popunjavanja pora nosača metalnim solima aktivnog metala i odgovarajućih metala modifikatora. Utvrđeno je da sa porastom sadržaja srebra dolazi do povećanja zapremine makropora... Multicomponent catalytic systems consisting of active component (metallic Ni) and appropriate metals (Mg, Ag, Cu) deposited onto a prepared support (activated diatomite) were investigated, as well as their application as catalysts in the process of partial hydrogenation of edible oils. Starting material used for the synthesis of the catalyst support was raw diatomite from domestic sources (Baroševac diatomite deposit, eastern zone of the Kolubara coal basin). Raw diatomite properties were modified through chemical and thermal treatment resulting in a catalyst support with high silicon oxide content. Investigation of the textural properties and granulometric composition showed that the obtained catalyst support has macroporous structure and convenient granulometric composition appropriate for the obtention of Ni containing catalysts for the partial hydrogenation of vegetable oils. Synthesis of several catalyst samples was performed by the precipitation of Ni compounds and appropriate metals from aqueous solutions of their nitrate salts onto the prepared diatomite support, using sodium carbonate (PDI catalysts) and urea (DPU catalysts) as precipitants. Thorough experiments were carried out in order to investigate the influence of the PDI- and DPU-Ni/D catalyst precursor synthesis conditions on the degree of reduction. Investigation of the influence of the SiO2/Ni molar ratio and heating rate on the degree of reduction of the PDI-Ni/D catalyst precursor showed that lower SiO2/Ni molar ratio and lower heating rate increase the reduction degree. Investigation of the dependence of the degree of reduction on the DP time indicated that shorter DP times enable higher reduction degree. Physico - chemical characterization of the PDI- and DPU-Ni/D catalyst precursors was performed using the following methods: (1) standard quantitative chemical analysis; (2) X-ray diffraction (XRD) and infrared (IR) spectroscopy; (3) Hg-porosimetry and N2-physisorption (4) temperature-programmed reduction (TPR); (5) H2-chemisorption; (6) scanning electron microscopy (SEM) and energy dispersed spectroscopy (EDS); (7) diffuse reflectance UV-Vis spectroscopy (DR UV-Vis); and (8) X-ray photoelectron spectroscopy (XPS). Results of the XRD analysis of non-reduced PDI- and DPU-Ni/D catalyst precursors showed that, beside Ni2+ phases in the form of basic nickel carbonate (PDI-Ni/D precursors) and turbostratic nickel hydroxide (DPU-Ni/D precursors), there are also Ni hydrosilicates, originating in the interaction between the active metal and catalyst support. Analysis of XRD diffractograms of the reduced and passivated precursors and in situ XRD-H2 diffractograms was used for the size determination of metallic nickel and modifier metal (Ag) crystallites. Results of the investigation of non-reduced precursors of the Ni/D catalysts using IR spectroscopy confirmed the presence of Ni2+ phases of basic carbonate and hydrosilicates and indicated that the Ni hydrosilicate phase prevail comparing to that of Ni carbonate (PDI-Ni/D precursors). It was shown that in the DPU-Ni/D catalyst precursors the nature of Ni2+ phase depends on the DP time...

In this paper, the influence of liquid and gas flow rates, vibration intensity, and solid phase volume fraction on the axial mixing of the liquid phase in axial direction of reciprocating plate columns with different geometry (columns RPC1 and RPC2: inner column diameter 2.54 and 9.2 cm, working height 173 and 86 cm, number of perforated plates 65 and 15, and fractional free area 51 and 45.4 %, respectively) was investigated. The tap water flowing down (superficial velocity: up to 0.9 cm/s), air (superficial velocity to 1.5 cm/s) and the polypropylene spheres (diameter 8.3 mm, density 890 kg/m3, ratio up to 8.43 %) were used as the liquid, gas and solid phase, respectively. To study the axial dispersion (axial mixing) the resident-time distribution function was used, which was determined by the pulse input method with sorbic acid used as a tracer (tracer concentration was measured at the column outlet).

U ovom radu je ispitivano dobijanje neravnotežnin struktura u metalima mehanohemijskim tretmanom. Strukturne i termijske karakteristike prahova mehanohemijski tretiranih različito vreme mlevenja su ispitivane rendgenskom strukturnom analizom, diferencijalnom skanirajućom kalorimetrijom, diferencijalnom termijskom analizom, kao i skanirajućom i transmisionom elektronskom mikroskopijom. Eksperimentalni rezultati su diskutovani sa kinetičkog i termodinamičkog stanovišta. Mehanohemijski tretmani, tj. mehaničko legiranje smeša čistih prahova aluminijuma i molibdena različitih početnih sastava (Al-0, 3, 10, 17, 20, 27, 50, 75 i 100 at.%Mo) su rađeni u horizontalnom kugličnom mlinu. U svim sličajevima mlevenje proizvodi nanokristalnu i/ili amorfnu strukturu. Tokom naknadnog termijskog tretmana, ovakvi metastabilni proizvodi lako reaguju obrazujući intermetalna jedinjenja: Al12Mo, Al5Mo, Al4Mo, AlgMo3 i AlMo3. Smesa prahova nikla i molibdena (Ni-50 at.%Mo) je mlevena u različitim tipovima mlinova. Mehaničkim legiranjem u horizontalnom kuglicnom mlinu dobija se amorfna faza. U planetarnom i vibracionom mlinu, zbog veće energije mlevenja, dobija se neuređeno intermetalno jedinjenje. Mehanohemijska reakcija amortizacije u oba ispitivana sistema je slična i odvija se u četiri stupnja: (i) obrazovanje veoma finog kompozitnog praha, (ii) obrazovanje čvrstog rastvora Al(Mo) ili Ni(Mo), (iii) transformacija presićenog čvrstog rastvora u amorfnu fazu i (iv) postepeno rastvaranje zaostalih kristalita molibdena u amorfnoj matrici. In this study the formation of non-equilibrium structures in metals by mechanochemical treatment has been investigated. The structural and thermal properties of powders mechanochemically treated for various milling times have been studied by X-ray diffraction, differential scanning calorimetry, differential thermal analysis, as well as scanning and transmission electron microscopy. The experimental results were discussed from kinetic and thermodynamic point of view. Mechanochemical treatment, i.e. mechanical alloying of mixture of aluminium and molybdenum powders of various starting compositions (Al-O, 3, 10, 17, 20, 27, 50, 75 and 100 at.%Mo) was performed in a horizontal ball mill. In all cases milling produced nanocrystalline or/and amorphous structures. During subsequent heat treatment such metastable products easily react leading to the formation of intermetallic phases: Al12Mo, Al5Mo, Al4Mo, Al8Mo3 and AlMo3. Mixture of nickel and molybdenum powders (Ni-50 at.%Mo) was treated in various types of mills. Mechanical alloying in the horizontal ball mill yields an amorphous phase while in planetary and vibrating ball mill a disordered intermetallic compound was produced as a result of greater milling energies. The formation of amorphous phase in both systems is similar and occurs in four stages: (i) formation of very fine composite powders, (ii) formation of solid solution either Al(Mo) or Ni(Mo), (iii) collapse of supersaturated solid solution into the amorphous phase and (iv) gradual dissolution of residual molybdenum crystallites into the amorphous matrix.