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Experimental investigation of gas-liquid mass transfer of ozone in water, in bubble column with two-fluid nozzle gas distributor (BKDM), under different operating conditions, is presented in this work. The main objective was to determine the ozone volumetric mass transfer coefficient, kL a, in calm uniform section of the column, under different values of gas and liquid flow rates. Obtained values of these coefficients were compared with the values in countercurrent bubble column. The critical liquid flowrate, when gas hold up reaches its maximum, was experimentally determined. It was shown that the maximum value of the ozone volumetric mass transfer coefficient is obtained just when liquid flowrate is at its critical value. U ovom radu prikazani su rezultati eksperimentalnih ispitivanja prenosa mase gas-tečnost pri ozonizaciji vode u barbotažnoj koloni sa dvofluidnom mlaznicom (BKDM) pod različitim operativnim uslovima. Cilj ovih ispitivanja bio je određivanje vrednosti zapreminskog koeficijenta prenosa mase ozona u vodi, kLa, u mirnoj zoni kolone, pri različitim protocima gasne i tečne faze. U radu je dato i poređenje kLa u BKDM sa vrednostima kLa u klasičnoj protivstrujnoj barbotažnoj koloni sa poroznom pločom tj. fritom. Eksperimentalno je određena vrednost kritičnog protoka tečnosti, pri kojem sadržaj gasa u disperziji, u mirnoj zoni kolone, dostiže svoju maksimalnu vrednost. Rezultati su pokazali da se pri kritičnom protoku tečnosti dobija maksimalna vrednost zapreminskog koeficijenta prenosa mase ozona u vodi.

In this paper substance transfer phenomena in the multistage reactive system were investigated.Substance transfer between liquid and gas phases in a distillation packed column with reactionesterification was examined. Efficiency of substance transfer were examined by HTU-Height of transferunits and volumetric substance transfer coefficients. The esterification reaction of the ethanol andacetic acid was examined. Based on derived mathematical model the total height of transfer units andindividual height of transfer units for the liquid and gas phases were determined. The investigation wasperformed by computer simulation and experiments. Several correlation models for HTU/NTU andsubstance transfer coefficients were studied. The correlations for component transfer were derived inquaternary systems ethanol-ethyl acetate-acetic acid -water.

In this paper substance transfer rate in the multistage system was investigated. Substance transfer between liquid and gas phases in a distillation packed column with packing was examined. Substance and heat transfer rate were examined and substance transfer coefficients were determined. Efficiency of substance transfer were examined by height of transfer units and volumetric substance transfer coefficients. Based on derived mathematical model the total height of transfer units and individual height of transfer units for the liquid and gas phases were determined. The investigation was performed by computer simulation and experiments. Several correlation models for height of transfer units and substance transfer coefficients were studied.

The Cu2+ sorption onto HAP was investigated as a function of time, in the concentration range 5·10-4 - 5·10-3 mol/dm3. The experimentally obtained kinetic data were fitted with the intraparticle diffusion model. The correlation coefficients were low considering the overall reaction period. However, q versus t0.5 plots could be divided into three segments, out of which the second linear segment can be attributed to the intraparticle diffusion. Intraparticle diffusion rate constants (ki) increased from 3.57·10-3 to 7.80·10-3 mmol/g min0.5 with the increase of the initial Cu2+ concentration. As the lines did not pass through the origin it was concluded that intrapaticle diffusion is not the only rate-controlling step. Physical chemistry 2008 : 9th international conference on fundamental and applied aspects of physical chemistry; Belgrade (Serbia); 24-28 September 2008

Sistemi koji obuhvataju interakcije fluid-čestice nalaze široku primenu u različitim procesima. Jedan od najšire primenjenih sistema fluid-čestice u industriji je fluidizovani sloj čestica. Sistemi sa fluidizovanim slojem čestica primenjuju se u različitim granama industrije kao što su: separacija i klasifikacija čestica, adsorpcija, jonska izmena, katalitički kreking, operacijama u hidrometalurgiji, operacijama prerade otpadnih voda. Periodično ispiranje peščanih filtera je jedna od najšire primenjenih sistema fluidizovanog sloja čestica sa tečnošću. U okviru ovog rada primenjene su različite metode za karakterizaciju veličine i oblika nesferičnih polidisperznih smeša kvarcnog peska. Na osnovu dobijenih rezultata predložene su korelacione jednačine za određivanje ekvivalentnih prečnika čestica i faktora oblika. Za određivanje sferičnosti korišćenje su različite metode: metoda na osnovu eksperimentalnog određivanja pada pritiska u pakovanom sloju čestica i metoda bazirana na određivanju brzine taloženja nesferičnih čestica. Karakterizacija čestica peska razdvojenih po visini fluidizovanog sloja tokom fluidizacije polidisperzne smeše vršena je korišćenjem softverskog paketa SigmaScan (Image Analysis). U programu Sigma Scan obrađene su skenirane slike čestica upoređivanjem sa prethodno zadatim referentnim sistemom. Na osnovu obrade skenirane slike, kao izlazni podaci dobijaju se karakteristične veličine snimljenih čestica: veličina čestica (projektovani prečnik), faktor oblika čestica (odnosno dvodimenzione projekcije čestica), projektovana površina čestica, zapremina čestica, kao i broj snimljenih čestica. Na osnovu ovih podataka formirane su krive frakcione i kumulativne raspodele veličina čestica peska pre i tokom fluidizacije na osnovu čega se dobija jasna slika o segregacije čestica do koje dolazi tokom fluidizacije. Razdvajanje slojeva tokom fluidizacije izvršeno je hidrauličkom klasifikacijom materijala. Pokazano je da se raspodela veličine čestica frakcija peska približno pokorava normalnom zakonu raspodele, koji može da se opiše Gaus-ovom jednačinom. Analizom raspodele veličine čestica sa vrha i sa dna sloja određeno je da će do segregacije čestica po veličini doći kada je odnos većih i manjih čestica u populaciji dR=dv/dm>1.5... The systems involving fluid-particle interaction are widely used in different industrial processes. One of the most widespread fluid-particle systems is fluidized bed of particles. Fluidized beds are used in many applications, such as solids separation and classification, adsorption, ion exchange, catalytic cracking, hydrometallurgical operations, wastewater treatment etc. The periodic back-washing of down flow granular filters, especially sand filters is one of the widest uses of liquid fluidized beds . Different methods for particle characterization were applied to the polydisperse sets of particles of quartz filtration sand in order to derive the correlations between equivalent diameters, sphericity and 2D shape factor. For the determination of sphericity using different methods, the following characteristics of the particles were experimentally determined: pressure drop of the packed bed of particles, terminal velocity of the particles and porosity at minimal fluidization. The sphericities obtained were critically evaluated and the best method for particle characterization was proposed. Size distribution of sand particles for fractions obtained by sieving follows approximately modified normal (Gaussian) distribution with respect to the projected particle diameter, while the shape factor decreases linearly with the increase in the projected particle diameter. Expansion of sand particles during fluidization follows Richardson-Zaki relationship. Intercept velocity, i.e. extrapolated value of fluid superficial velocity at =1 on the plot log(U) vs. log(), agree quite well with the experientaly determined mean free settling velocity of the cloud of about 30 randomly selected particles. During fluidization the beds were hydraulicaly separated into 10 subfractions which were subsequently analyzed. The results indicate that the bed is partially segregated for the fraction dp=0.75-1.25 mm during the fluidization at overall bed expansion of 35% since the smallest particles were concentrated at the top, while the largest particles were concentrated in the bottom zone. In the remaining part of the bed (about 80% of the total mass) the particles are well mixed. Similar experiments were performed with sand mixtures dp=1.60-2.00 mm, dp=1.40-2.00 mm, dp=1.166-2.00 mm...

Predmet ove doktorske disertacije proističe iz aktuelne problematike inženjerstva koštanog tkiva, vezane za procese osteointegracije, implantiranja, kao i rešavanja problema inflamacije na mestima ugradnje implanata. Prvi deo disertacije posvećen je problemima vezanim za biokompatibilnost i osteointegraciju materijala koji se koriste kao implanti u inženjerstvu koštanog tkiva. S tim u vezi, ispitivano je formiranje bioaktivnih prevlaka kalcijum hidroksiapatita (HAP) na površini dve vrste potencijalnih implanata: metalnih i keramičkih, biomimičnom metodom. Ova metoda je pogodna jer omogućava dobijanje HAP-a sličnih strukturnih i morfoloških karakteristika kao prirodna kost. Zasnovana je na korišćenju rastvora sličnog jonskog sastava kao krvna plazma (poznatih kao simulirajući telesni fluidi-STF) pa su i uslovi nukleacije HAP-a slični uslovima nukleacije u biološkim sistemima. Površina metala (nerđajući čelik) prethodno je aktivirana nabacivanjem tankog sloja silicijum dioksida, sa ugrađenim OH grupama koje služe kao aktivni centri heterogene nukleacije apatita. Keramički supstrat- porozni HAP tretiran je u biomimičnom medijumu u cilju unapređenja nanotopologije unutratrašnjih zidova poroznog nosača koja je optimalna za rast i aktivaciju ćelija koštanog tkiva. Tri različita polimera (PLGA, celuloza i alginat) korišćena su za funkcionalizaciju zidova poroznog nosača radi njegovog dodatnog nanodizajniranja i povećanja njegove aktivnosti na površini. STF, kao i STF kombinovan sa serumom iz fetusa govečeta i Iglovim medijumom korišćeni su kao bioaktivni tečni medijumi u kojima se odvija biomimična nukleacija apatita. Analizom faza formiranih u biomimičnom medijumu, metodom difrakcije X-zraka, potvrđeno je da je HAP formiran na površini svih uzoraka. Infracrvenom spektroskopijom je utvrđeno da se radi o HAP-u blago promenjene stehiometrije. Mikroskopija atomskih sila ukazala je na mehanizam nukleacije, dok je skenirajuća elektronska mikroskopija ukazala na morfologiju nukleirane faze. Merenjem mase, uz korekcije zapremine urađene BET metodom, pokazano je da debljina filma nukleiranog I HAP-a zavisi od vremena boravka uzoraka u biomimičnom medijumu, kao i od vrste izabranog biomimičnog medijuma. Ispitana je i bioprihvatljivost ovih materijala u in vitro i in vivo uslovima, pri čemu su dobijeni veoma dobri rezultati. U drugom delu disertacije pažnja je usmerena ka iznalaženju rešenja za probleme učestalih inflamacija koje se javljaju prilikom ugradnje implanata, kao i za tretiranje oboljenja koštanog tkiva na lokalnom nivou, kontrolisanim otpuštanjem leka na obolelo mesto. Cilj je da se razvije takav implantni materijal koji će imati odgovarajuće osobine osteokondukcije i osteoindukcije i istovremeno oslobađati biološki aktivne molekule na međupovršinu živog tkiva i implanta. Veliki potencijal za takvu primenu pokazao je hidroksiapatit koji je jedan od najzastupljenijih materijala u inženjerstvu koštanog tkiva, zbog čega je i izabran kao model-sistem za ispitivanje kinetike otpuštanja antibiotika koji se koriste za lečenje infekcija koštanog tkiva. Antibiotici su inkapsulirani u dva različita sistema: u polimer koji je zatim deponovan na porozni apatitni nosač i u tablete dobijene kompresijom praškastog apatita. Pored apatitnih nosača, kreiran je i nosač za kontrolisano otpuštanje lekova na bazi SiO2, i to metodom sprej sušenja koja omogućava dobijanje SiO2 čestica složenog strukturnog dizajna uz istovremenu imobilizaciju leka na česticama. Zatim je praćena brzina otpuštanja antibiotika iz ovih sistema. Utvrđeno je da pogodno dizajnirani porozni nosači mogu zadržati lek dovoljno dugo vremena da bi se kontrolisao proces lokalne inflamacije. The subject of this PhD thesis is derived from current problems of bone tissue engineering, related to processes of osteointegration, implantation and resolution of the problems arising from the implantation site inflammation. The first part of the thesis examines problems of biocompatibility and osteointegration of materials used as implants in bone tissue engineering. Thus, the formation of bioactive coatings of calcium hydroxyapatite (CHA) on two potential types of implants, metal and ceramic, using biomimetic method, was investigated. This method is appropriate because it enables formation of CHA with similar structural and morphological properties of a natural bone. It is based on the use of the solution of similar ionic composition as human plasma (they are known as simulated body fluids- SBF) and the conditions of CHA nucleation are similar to the conditions found in biological systems. The metal surface (stainless steel) was previously activated by spraying with the thin silica film, with OH groups that act as active centers of heterogeneous nucleation of apatite. Ceramic substrate- porous CHA scaffold was treated in biomimetic medium in order to improve nanotopology of scaffold inner walls, optimal for growth and activation of bone tissue cells. Three different polymers (PLGA, cellulose and alginate) were used for the functionalization of the scaffold walls in order to achieve its additional nanodesigning and increase of its surface activity. SBF, as well as the SBF combined with fetal calf serum and Eagle’s minimal essential medium, were used as bioactive liquid medium, where biomimetic nucleation of apatite occurs. The analysis of the phases formed in the biomimetic medium, using X ray diffraction method, confirmed that CHA was formed on the surface of all samples. Infrared spectroscopy showed that this is CHA of slightly shifted stoichiometry. Atomic force microscopy pointed the mechanism of nucleation, while scanning electron microscopy showed the morphology of nucleated phases. Mass measurements, with volume corrections made using the BET method, showed that the thickness of nucleated CHA film depends on the aging time of samples in SBF and the type of selected III IV biomimetic medium. Also, bio-acceptability of these materials was investigated in vitro and in vivo and very good results were obtained. The second part of the thesis focuses on resolving the problem of frequent inflammation that occurs during implantation, as well as the problem of local treatment of bone tissue diseases, using controlled drug delivery to the affected area. The goal is to develop such an implant material that will have required osteoinductive and osteoconductive properties and simultaneously release biologically active molecules at the interface of living tissue and the implant. Hydroxyapatite, as the one of the most common materials in bone tissue engineering, showed a great potential for this applications, and therefore it was chosen as a model system to study release kinetics of antibiotics that are used in treatments of bone tissue infections. Antibiotics were encapsulated in two different systems: in the polymer that was later incorporated in CHA scaffold and tablets obtained by compression of apatite powder. Besides apatite carriers, carrier for controlled drug delivery based on SiO2 was also created, using the spray drying method that allows obtaining the SiO2 particles of complex structural design with simultaneous drug immobilization on these particles. Afterwards, the release rate of antibiotics from these systems was measured. It was concluded that suitably designed porous carriers can sustain a drug long enough to control the process of local inflammation.

Predmet rada ove doktorske disertacije je bio ispitivanje sorpcije Cu (II)- jona sintetičkim HAP-om i prirodnim sorbentima zeolitom, glinom i dijatomitom, u cilju definisanja ravnoteže i kinetike procesa pri različitim uslovima. Fizičko-hemijska karakterizacija je pokazala da se sintetički HAP sastoji od čistog nestehiometrijskog, kalcijum deficitarnog, kalcijum-hidroksiapatita, zeolit od klinoptilolita, dok je glina kompozit ilita, kaolinita i montmorilonita. Glavna faza u dijatomitu je amorfni silicijum-dioksid. Takođe, HAP i zeolit su okarakterisani kao mezoporozni sorbenti specifičnih površina 58 m2/g i 23 m2/g, redom, dok su se glina i dijatomit pokazali neporozni, nižih specifičnih površina od 8 m2/g i 5 m2/g. Definisana je pHPZC koja iznosi 6,6 za HAP, glinu i dijatomit, dok je kod zeolita nešto viša i iznosi 7,5. Dobijene vrednosti pHPZC HAP-a, gline i zeolita su u dobroj saglasnosti sa literaturom, dok pHPZC dijatomita do sada nije objavljena. Ispitivanjem uticaja inicijalne pH vrednosti rastvora na ravnotežu, pokazano je da se finalne pH vrednosti razlikuju u zavisnosti od ispitivanog sorbenta. Generalno, ravnotežne pH vrednosti najviše rastu sa porastom inicijalnih pH rastvora u oblasti 2 - 4. Oblast platoa, u kome su finalne pH vrednosti nezavisne od inicijalnih i koja ukazuje na puferska svojstva sorbenata, zavisi od vrste sorbenta i koncentracije jona metala u rastvoru. Dalje povećanje polaznih pH prouzrokuje porast i finalnih. Krive zavisnosti sorbovane količine od inicijalnih pH su istog oblika kao i krive pH finalno-pH inicijalno, što se objašnjava povećanom rastvorljivoću sorbenata ili njihovih komponenti i kompeticijom Cu(II) i H+ jona u jako kiselim rastvorima. Porast finalnih pH iznad 6 dovodi do precipitacije bakar – hidroksida što rezultira 100% uklanjanjem jona metala iz rastvora. Maksimalni sorpcioni kapaciteti prema Cu(II)- jonima, na sobnoj temperaturi, opadaju u nizu: HAP (0,585 mmol/g) > zeolit (0,128 mmol/g) > glina (0,098 mmol/g) > dijatomit (0,047 mmol/g). U datim eksperimentima je utvrđen pad pH vrednosti rastvora u odnosu na početnu, što ukazuje na postojanje mehanizma specifične sorpcije, koji je najdominantniji tokom sorpcije na dijatomitu. Za vezivanje jona metala ispitivanim materijalima, odgovoran je i mehanizam jonske izmene, gde se Cu(II)- joni izmenjuju sa Ca2+ jonima sa površine HAP-a, odnosno sa jonima Na+, K+, Ca2+, Mg2+ sa površine prirodnih sorbenata. Stabilnost sistema sorbent/jon metala je ispitana u kiselom rastvoru za izluživanje i zavisi od vrste sorbenta, kao i prethodno sorbovane količine Cu(II)- jona. Sa porastom sorbovane količine na uzorcima HAP-a i dijatomejske zemlje, raste i procenat desorbovane količine, dok desorpcija sa zeolita i gline pokazuje suprotan trend - u kiseloj sredini su stabilniji uzorci sa većom sorbovanom količinom jona metala. Ako posmatramo desorbovanu količinu izraženu u mmol/g ili mg/g, ona je veća na uzorcima koji su više zasićeni, nezavisno od vrste sorbenta. Kinetika procesa je ispitana u različitim šaržnim sistemima. Prvi sistem su pojedinačne šarže sa mešanjem na horizontalnom šejkeru, gde je proces sorpcije ispitan u funkciji od početne koncentracije Cu(II)- jona na svim ispitanim sorbentima. Drugi šaržni sistem je sud sa mešalicom u kom je ispitana kinetika procesa sorpcije HAP-om i zeolitom u funkciji od koncentracije sorbata, mase sorbenta, brzine mešanja, a za zeolit i od granulacije sorbenta. Pokazano je da je sorpcija glinom i dijatomitom, kao neporoznim sorbentima, limitirana otporom u filmu fluida. Nasuprot tome, difuzija u filmu fluida tokom sorpcije na šejkeru HAP-om i zeolitom je značajna na početku procesa, tokom prvih 15 minuta. Vrednosti zapreminskog koeficijenta prenosa mase su izračunate Boyd-ovim modelom. Dobijene vrednosti kf·a su nezavisne od početne koncentracije Cu(II)- jona u rastvoru i variraju oko srednje vrednosti 0,046 1/min za HAP, 0,023 1/min za zeolit, 0,017 1/min za glinu i 0,031 1/min za dijatomit. Iz prethodno navedenog proizilazi da je kf·a kod neporoznih sorbenata funkcija veličine čestica, tj. najveći je za najsitnije čestice jer je i specifična površina veća. Primenom jednačina za difuziju u porama, pokazano je da efektivne difuzivnosti blago opadaju sa porastom c0 za sorpciju HAP-om, dok za sorpciju zeolitom Deff nije funkcija c0. Zavisnost Deff od c0 i nezavisnost kfa od c0 kod HAP-a može se objasniti suprotnostrujnom difuzijom odlazećih katjona sa površine sorbenta, kao i elektrostatičkim odbijanjem istoimenih naelektrisanja koji su zanemarljivi u masi fluida, ali se ne mogu zanemariti u unutrašnjosti pora. Analizom rezultata sorpcije HAP-om u sudu sa mešanjem, dobijeno je da kf·a za prvih 10 minuta procesa ne zavisi od mase sorbenta i brzine mešanja, a blago opada sa porastom početne koncentracije metala u rastvoru, što je najverovatnije uslovljeno postojanjem otpora difuzije u porama. Nasuprot tome, kf·a izračunat za zeolit ne zavisi od mase sorbenta, kao ni početne koncentracije, ali raste sa porastom brzine mešanja i padom veličine čestica sorbenta. Efektivne difuzivnosti i kod HAP-a i kod zeolita ne zavise od mase sorbenta, kao ni brzine mešanja. Deff opada sa porastom c0 usled postojanja suprotnostrujne difuzije u porama, a raste sa porastom veličine čestica. Kao krajnji zaključak, može se izvesti da je za procese sorpcije HAP-om i zeolitom na šejkeru u prvih 15 minuta limitirajući otpor u filmu fluida, a zatim difuzija u porama sorbenta, pri čemu se dešava sorpcija u mezoporama. Takođe, šejker ne obezbeđuje dovoljno efikasno mešanje, te su vrednosti kfa i Deff značajno niže od vrednosti dobijenih za sud sa mešanjem. Sorpcija HAP-om u sudu sa mešanjem je limitirana samo difuzijom u porama jer se difuzija u filmu fluida i zasićenje površine dešava skoro trenutno. Tokom sorpcije zeolitom u sudu sa mešanjem, prvih 10 minuta procesa značajan je otpor u filmu, a nakon toga otpor u porama sorbenta. The subject of the work presented in this dissertation was to investigate the sorption of Cu (II)- ions onto synthetic hydroxyapatite (HAP)-and natural sorbents: zeolite, clay and diatomite, in order to define process equilibrium and kinetics under different conditions. Physico-chemical characterization showed that synthetic HAP was consisted of pure non-stoichiometric, calcium deficient, calcium hydroxyapatite, zeolite of clinoptilolite, while clay was the composite of illite, kaolinite and montmorillonite. The main phase of diatomite was amorphous silicon dioxide. Also, HAP and zeolite were characterized as a mesoporous sorbents with specific surface areas of 58 m2 / g and 23 m2 / g, respectively, while the clay and diatomite were non-porous, with low specific surface areas of 8 m2/g and 5 m2 / g. pHPZC of 6.6 was defined for HAP, clay and diatomite, while higher value of 7.5 was obtained for zeolite. Obtained results for pHPZC for HAP, clay and zeolite are in good agrement with literature, while pHPZC of diatomite has not been published. The investigation of influence of initial solution pH in the range of 2 - 10 on equilibrium showed that the final pH values varied depending on the tested sorbent. In general, final pH values increased the most in pH range 2 – 4. Areas of the plateau, where the final pH values were independent on the initial pH indicating the buffering properties of sorbents, were dependent on the sorbent and the concentration of metal ions in solution. Further increase of initial pH caused increase of final pH values. The plots of sorbed amounts vs. initial pH were of the same shape as plots pH final vs. pH initial, which can be explained with higher solubility of sorbents and their components and competition between Cu(II) and H+ ions in the strong acidic media. The final pH increase above 6 caused copper hydroxide precipitation and 100 % removal of metal ions from solution. The maximal sorption capacities at room temperature decreased in the order: HAP (0,585 mmol/g) > zeolite (0,128 mmol/g) > clay (0,098 mmol/g) > diatomite (0,047 mmol/g). In these experiments pH drop was observed, signifying the existence of specific cation sorption mechanism which was the most dominant during the sorption onto diatomite. Also, ion-exchange mechanism between Cu(II)- ions and Ca2+ ions from HAP surface was responsible for metal bonding, as well as ion-exchange with Na+, K+, Ca2+, Mg2+ from surfaces of natural mineral sorbents. The stability of system sorbent/ metal was investigated in acidic leaching solution and it was dependant on sorbent type, as well as on the previously loaded amounts. With increase of loaded metal amounts onto HAP and diatomite, the percentages of desorption also increased, while the opposite was observed for desorption from zeolite and clay- the samples with higher loadings were more stable in the acidic media. The desorbed amounts expressed in mmol/g or mg/g were higher for the more saturated samples, independent of sorbent type. The process kinetics was investigated as a function of initial metal concentration in batch system, on horizontal shaker. It was shown that the sorption onto non-porous sorbents, clay and diatomite was limited with diffusion film resistance. Contrary, the film diffusion was significant only during the first 15 minutes of process onto HAP and zeolite. The values of volumetric mass transfer coefficient kf·a were calculated using Boyd model. The values of kf·a were independent on initial concentration, and varied around averaged value of: 0,046 1/min for HAP, 0,023 1/min for zeolite, 0,017 1/min for clay and 0,031 1/min for diatomite. According to this it can be concluded that kf·a was a function of particle size for nonporous sorbents, i.e. it was highest for the smallest particles because specific surface area was higher. The obtained values for kf·a decreased in the order: HAP>diatomite>zeolite>clay, but probably this order would be different if the zeolite particles were smaller, where value for kf·a onto zeolite would be higher. Using pore diffusion models, it was shown that the effective diffusivities slightly decreased with c0 increase, while for sorption onto zeolite Deff was independent on c0. Dependence of Deff on c0 and independence of kfa on c0 can be explained by counter diffusion of cations released from sorbent surface, as well as with electrostatic repulsion of positive charged particles. These phenomena can be neglected in the fluid mass, but not inside the pores. From the analysis of results obtained for sorption onto HAP in the agitated vessel, it was observed that kf·a calculated for the first 10 minutes of the process was independent on sorbent mass and agitation speed, but slightly decreased with initial metal concentration increase, which was probably caused by the existence of pore diffusion resistance. Contrary, kf·a calculated for zeolite was independent on metal concentration and sorbent mass, but increased with agitation speed increase and particle size decrease. Effective diffusivities for sorption onto HAP and zeolite were independent on sorbent mass and agitation speed. Deff decreased with c0 increase because of counter diffusion inside the pores, but increased with particle size increase. Finally, it can be concluded that for the first 15 minutes of the sorption onto HAP and zeolite using shaker, the limiting step was film diffusion, and after that the pore diffusion, where sorption occurred inside the mesopores. Also, the mixing using shaker was not good enough, thus the obtained values for kfa and Deff were significantly lower than the values obtained for the sorption in the agitated vessel. The sorption onto HAP in the agitated vessel was limited only by pore diffusion because the film diffusion and surface saturation occurred almost instantaneously. The sorption onto zeolite in agitated vessel was governed by film diffusion during the first 10 minutes, whereas after that by diffusion inside the pores.

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.

U ovom radu izučavani su mehanizmi sorpcije teških metala korišćenjem dve forme minerala apatita: sintetičkog hidroksiapatita (HAP) i prirodnog apatita iz ležišta Lisina kod Bosilegrada (LA). Karakterizacija materijala je izvršena korišćenjem metode difrakcije x-zraka. Utvrđeno je da je sintetički apatit (HAP) čist hidroksiapatit molekulske formule Ca10(PO4)6(OH)2, dok je prirodni apatit (LA) smeša minerala kvarca, muskovita i fluorapatita. Mehanizmi sorpcije izučavani su korišćenjem teorijskog modela stabilnosti čvrste faze, kao i eksperimentalnim proučavanjem sorpcije olova iz vodenog rastvora. Teorijski matematički model stabilnosti čvrste faze baziran je na izračunavanju jon-jon interakcionih potencijala. Ovaj model upotrebljen je za procenu stabilnosti čvrste faze nastale reakcijom zagađujućih materija sa prirodnim i sintetičkim apatitom. Primenjeni model omogućava preliminarni izbor najpogodnijeg aditiva za imobilizaciju teških metala u zagađenom zemljištu ili podzemnim vodama sa stanovišta stabilnosti novonastale čvrste faze. Detaljno su razmotreni sledeći sistemi: Cd/HAP, Pb/HAP, Pb/prirodni apatiti i As/HAP. Na osnovu prikazanih rezultata predloženi su dominantni mehanizmi u procesima sorpcije zagađujućih materija u ispitivanim sistemima. U radu su izvršena eksperimentalna ispitivanja i modelovanje kinetike sorpcije olova iz vodenih rastvora korišćenjem prirodnog i sintetičkog apatita na tri temperature. Za modelovanje eksperimentalnih podataka korišćeni su kinetički modeli pseudo-prvog i pseudo-drugog reda. Utvrđeno je da model pseudo-drugog reda dobro opisuje kinetiku sorpcije olova u oba ispitivana sistema. Takođe su izvršena eksperimentalna ispitivanja adsorpcionih izotermi olova na hidroksiapatitu i prirodnom apatitu. Za analizu sorpcionih podataka korišćeno je pet modela adsorpcionih izotermi. Na osnovu primene ANOVA statističke analize utvrđeno je da Freundlich-ova adsorpciona izoterma najbolje opisuje eksperimentalne podatke u oba sistema. Analiza svih dobijenih rezultata ukazuje na mogućnost primene prirodnog apatita iz ležišta Lisina, kao jeftine polazne sirovine, za remedijaciju zemljišta i podzemnih voda zagađenih teškim metalima. In this work, the mechanisms of heavy metal sorption by two forms of mineral apatite were studied. The materials used include synthetic hydroxyapatite (HAP) and natural apatite from Lisina ore deposit (LA). The materials were characterized by x-ray diffraction. It was shown that synthetic apatite is pure hydroxyapatite, with molecular formula Ca10(PO4)6(OH)2, while natural apatite is a mixture of three minerals: quartz, muscovite and fluorapatite. The mechanisms were investigated using theoretical model of the solid matrix/impurity system stability as well as by experimental investigations of dissolved Pb sorption by HAP and LA. The theoretical model of the solid matrix/impurity system stability is based on ion-ion interaction potential calculation. This model was used to estimate the stability of the solid phase obtained by the reaction of heavy metals with synthetic and natural apatite. The applied model can be used for pre-selection of the most suitable amendment for heavy metal immobilization in polluted soils and ground water, based on the stability of the newly formed solid phase. The following systems were investigated in detail: Cd/HAP, Pb/HAP, Pb/natural apatites and As/HAP. Based on the results obtained, the dominant mechanisms involved in reactions in the investigated systems were suggested. In this work, experimental investigations and modeling of the kinetics of Pb sorption by natural and synthetic apatites were carried out at three temperatures. Two kinetic models were used: pseudo-first and pseudo-second order model. It was concluded that pseudo-second order model describes the kinetics of the processes in both systems best. Experimental investigations of the sorption isotherms were also carried out. Five sorption isotherms were used to model the experimental results. Using ANOVA statistical analysis it was concluded that Freundlich isotherm model described both systems with the greatest accuracy. Based on the analysis of all the results obtained, it can be concluded that natural apatite from Lisina ore deposit is a promising material for heavy metal remediation in polluted soils and ground water.

In this work, the mechanisms of heavy metal sorption by two forms of mineral apatite were studied. The materials used include synthetic hydroxyapatite (HAP) and natural apatite from Lisina ore deposit (LA). The materials were characterized by x-ray diffraction. It was shown that synthetic apatite is pure hydroxyapatite, with molecular formula Ca10(PO4)6(OH)2, while natural apatite is a mixture of three minerals: quartz, muscovite and fluorapatite. The mechanisms were investigated using theoretical model of the solid matrix/impurity system stability as well as by experimental investigations of dissolved Pb sorption by HAP and LA. The theoretical model of the solid matrix/impurity system stability is based on ion-ion interaction potential calculation. This model was used to estimate the stability of the solid phase obtained by the reaction of heavy metals with synthetic and natural apatite. The applied model can be used for pre-selection of the most suitable amendment for heavy metal immobilization in polluted soils and ground water, based on the stability of the newly formed solid phase. The following systems were investigated in detail: Cd/HAP, Pb/HAP, Pb/natural apatites and As/HAP. Based on the results obtained, the dominant mechanisms involved in reactions in the investigated systems were suggested. In this work, experimental investigations and modeling of the kinetics of Pb sorption by natural and synthetic apatites were carried out at three temperatures. Two kinetic models were used: pseudo-first and pseudo-second order model. It was concluded that pseudo-second order model describes the kinetics of the processes in both systems best. Experimental investigations of the sorption isotherms were also carried out. Five sorption isotherms were used to model the experimental results. Using ANOVA statistical analysis it was concluded that Freundlich isotherm model described both systems with the greatest accuracy. Based on the analysis of all the results obtained, it can be concluded that natural apatite from Lisina ore deposit is a promising material for heavy metal remediation in polluted soils and ground water. U ovom radu izučavani su mehanizmi sorpcije teških metala korišćenjem dve forme minerala apatita: sintetičkog hidroksiapatita (HAP) i prirodnog apatita iz ležišta Lisina kod Bosilegrada (LA). Karakterizacija materijala je izvršena korišćenjem metode difrakcije x-zraka. Utvrđeno je da je sintetički apatit (HAP) čist hidroksiapatit molekulske formule Ca10(PO4)6(OH)2, dok je prirodni apatit (LA) smeša minerala kvarca, muskovita i fluorapatita. Mehanizmi sorpcije izučavani su korišćenjem teorijskog modela stabilnosti čvrste faze, kao i eksperimentalnim proučavanjem sorpcije olova iz vodenog rastvora. Teorijski matematički model stabilnosti čvrste faze baziran je na izračunavanju jon-jon interakcionih potencijala. Ovaj model upotrebljen je za procenu stabilnosti čvrste faze nastale reakcijom zagađujućih materija sa prirodnim i sintetičkim apatitom. Primenjeni model omogućava preliminarni izbor najpogodnijeg aditiva za imobilizaciju teških metala u zagađenom zemljištu ili podzemnim vodama sa stanovišta stabilnosti novonastale čvrste faze. Detaljno su razmotreni sledeći sistemi: Cd/HAP, Pb/HAP, Pb/prirodni apatiti i As/HAP. Na osnovu prikazanih rezultata predloženi su dominantni mehanizmi u procesima sorpcije zagađujućih materija u ispitivanim sistemima. U radu su izvršena eksperimentalna ispitivanja i modelovanje kinetike sorpcije olova iz vodenih rastvora korišćenjem prirodnog i sintetičkog apatita na tri temperature. Za modelovanje eksperimentalnih podataka korišćeni su kinetički modeli pseudo-prvog i pseudo-drugog reda. Utvrđeno je da model pseudo-drugog reda dobro opisuje kinetiku sorpcije olova u oba ispitivana sistema. Takođe su izvršena eksperimentalna ispitivanja adsorpcionih izotermi olova na hidroksiapatitu i prirodnom apatitu. Za analizu sorpcionih podataka korišćeno je pet modela adsorpcionih izotermi. Na osnovu primene ANOVA statističke analize utvrđeno je da Freundlich-ova adsorpciona izoterma najbolje opisuje eksperimentalne podatke u oba sistema. Analiza svih dobijenih rezultata ukazuje na mogućnost primene prirodnog apatita iz ležišta Lisina, kao jeftine polazne sirovine, za remedijaciju zemljišta i podzemnih voda zagađenih teškim metalima.

Sušеnjе је оpеrаciја kоја је vеоmа zаstuplјеnа u hеmiјskој, prеhrаmbеnој i fаrmаcеutskој industriјi i kао tаkvа prеdstаvlја znаčајnоg kоrisnikа еnеrgiје. Izbоr аdеkvаtnоg sistеmа zа sušеnjе је slоžеn prоcеs i zаhtеvа pоtpunо pоznаvаnjе kаrаktеristikа pоlаznоg mаtеriјаlа kао i оčеkivаnih kаrаktеristikа finаlnоg prаškаstоg prоizvоdа. Pоstupci sušеnjа sе intеnzivnо istrаžuјu u svеtu sа cilјеm pоvеćаnjа еnеrgiјskе еfikаsnоsti, rаzvоја štо kоmpаktniје оprеmе, pоbоlјšаnjа kоntrоlе rаdnоg rеžimа prоcеsа, оdržаnjа kvаlitеtа prоduktа i оptimаlnоg kаpаcitеtа, smаnjеnjа еmisiје zаgаđivаčа. Sušеnjе vlаžnih mаtеriјаlа u pоkrеtnim slојеvimа inеrtnih čеsticа је rеlаtivnо nоvа tеhnоlоgiја i prеdstаvlја еkоnоmičniјu i еfikаsniјu аltеrnаtivu оstаlim, trеnutnо nајčеšćе kоrišćеnim, mеtоdаmа u cilјu dоbiјаnjа visоkо kvаlitеtnоg оsušеnоg prаškаstоg prоduktа. Istrаživаnjа izvršеnа u оkviru оvоg rаdа su u pоtpunој sаglаsnоsti sа nајnоviјim svеtskim trеndоvimа, s оbzirоm dа је pоslеdnjih gоdinа uоčеn znаtаn pоrаst nаučnih istrаživаnjа pоsvеćеn sušеnju mаtеriјаlа u pоkrеtnim slојеvimа inеrtnih čеsticа. Prikаzаni su rеzultаti istrаživаnjа prоcеsа sušеnjа rаstvоrа i suspеnziја u sistеmimа sа pоkrеtnim slојеvimа inеrtnih čеsticа, u fluidizоvаnоm slојu i fоntаnskоm slојu sа cеvnim umеtkоm. Еkspеrimеntаlnа ispitivаnjа su rаđеnа nа lаbоrаtоriјskim аpаrаturаmа i nа uvеćаnim lаbоrаtоriјskim (pоluindustriјskim) urеđајimа. U rаdu su prikаzаni rеzultаti dоbiјеni pri trеtmаnu suspеnziја rаzličitih mаtеriјаlа Ispitivаn је uticај оpеrаtivnih uslоvа nа pеrfоrmаnsе sistеmа zа sušеnjе i nа kvаlitеt prаškаstоg prоduktа. Prаćеnjеm аkumulаciје оsušеnоg mаtеriјаlа u slојu inеrtnih čеsticа sа vrеmеnоm i prоmеnе fluidо-dinаmičkih pаrаmеtаrа ispitivаn је uticај pоčеtnоg sаstаvа i vrstе suspеnziје kао i tеrmičkih pаrаmеtаrа sušеnjа nа kоntinuаlnоst prоcеsа. Izvršеnа је аnаlizа еfikаsnоsti sušеnjа i еnеrgiјskе еfikаsnоsti u funkciјi rаzlikе tеmpеrаturа izmеđu ulаznоg i izlаznоg vаzduhа u cilјu bоlјеg sаglеdаvаnjа pеrfоrmаnsi sistеmа zа sušеnjе sа еnеrgiјskоg аspеktа. Izvršеnа su prеliminаrnа ispitivаnjа nаknаdnоg dоsušivаnjа i hlаđеnjа prаškаstоg prоduktа iz primаrnе sušnicе u cilјu оbеzbеđivаnjа zаhtеvаnе rеziduаlnе vlаžnоsti prоduktа i еliminisаnjа njеnоg nаknаdnоg pоvеćаnjа. Ustаnоvlјеnо је dа ukupni bilаnsi prеnоsа mаsе i tоplоtе аdеkvаtnо prеdviđајu rаdni rеžim sistеmа zа sušеnjе u fluidizоvаnоm slојu inеrtnоg mаtеriјаlа. Rаzviјеn је mоdеl zа prеdviđаnjе pеrfоrmаnsi sušnicе sа fоntаnskim slојеm inеrtnih čеsticа i cеntrаlnоm cеvi. Моdеl bаzirа nа јеdnаčinаmа kоntinuitеtа, bilаnsimа kоličinе krеtаnjа zа fluid i čеsticе i bilаnsimа zа prеnоs tоplоtе i mаsе pоstаvlјеnim zа cеvni umеtаk. Prаktičnо kоrišćеnjе mоdеlа zаhtеvа i kоrеlаciје zа prеdviđаnjе kоеficiјеnаtа trеnjа fluid-čеsticе, fluid-zid trаnspоrtnе cеvi i čеsticе-zid trаnspоrtnе cеvi. Prеdlоžеni mоdеl zа sušеnjе suspеnziја u sušnici sа fоntаnskim slојеm i cеvnim umеtkоm, pоrеd izvеsnih оgrаničеnjа, sе mоžе iskоristiti zа оdrеđivаnjе оptimаlnih kаrаktеristikа оvаkvе sušnicе i zа rеdukоvаnjе brоја еkspеrimеntаlnih prоbа. Rаzviјеn је mоdеl zа prеdviđаnjе brzinе cirkulаciје inеrtnih čеsticа, štо је оd izuzеtnоg znаčаја zа prојеktоvаnjе i kоntrоlu prоcеsа sušеnjа u sušnici sа fоntаnskim slојеm inеrtnih čеsticа i cеvnim umеtkоm. Rаzviјеnа је i еkspеrimеntаlnо vеrifikоvаnа mеtоdа zа prеdviđаnjе brzinе zаgušеnjа i pоrоznоsti u vеrtikаlnоm pnеumаtskоm trаnspоrtu inеrtnih čеsticа. Ustаnоvlјеnо је dа је sušеnjе suspеnziја nа inеrtnim čеsticаmа јеdnоstаvnа i vrlо еfikаsnа tеhnikа zа svе mаtеriјаlе kојi sе nеćе slеpiti zа inеrtnе čеsticе i nа tај nаčin izаzvаti sintеrоvаnjе slоја. Nа оsnоvu pоrеđеnjа pеrfоrmаnsi dvа ispitivаnа sistеmа prоizilаzi dа је sušеnjе u fluidizоvаnоm slојu inеrtnih čеsticа еfikаsniјi prоcеs. Prеdnоsti оvоg sistеmа su i mаnjа kоličinа inеrtnih čеsticа, mаnji pаd pritiskа, јеdnоstаvniја rеgulаciја prоcеsа i znаtnо јеdnоstаvniје uvеćаnjе rаzmеrа prоcеsа. Sа drugе strаnе, prеdnоst sušеnjа nа inеrtnim čеsticаmа u fоntаnskоm slојu sа cеvnim umеtkоm је vrlо krаtkо vrеmе bоrаvkа mаtеriјаlа u zоni sušеnjа. U оvоm sistеmu mоgućе је sušiti i nеkе mаtеriјаlе kојi sаdržе оrgаnskе i biоlоškе kоmpоnеntе, štо prеdstаvlја оsnоvnu prеdnоst u оdnоsu nа sušnicu sа fluidizоvаnim slојеm inеrtnih čеsticа uslеd mаnjеg rizikа оd slеplјivаnjа slоја. Drying is one of the most involved process in the chemical, pharmaceutical and food processing industries and accordingly this unit operation is the most energy consuming industrial operation. The adequate dryer selection is a complex process and in that purpose it is necessary to completely know the feed characteristics as well as expected characteristics of final powdery product. The rapid investigations in drying technology are associated with the higher energy efficiency, enhanced drying rates, development of more compact dryers, better proces control, enhanced product quality and optimal capacity, emission reduction. Drying of wet materials in moving beds of inert particles is a relatively novel technology and it represents more economical and more efficient alternative to other most commonly used drying technologies to produce the high quality powdery materials. The investigations performed in the scope of this work are in the full agreement with the latest world trends regarding to the significant progress in the researches of drying processes in the moving beds of inert particles, especially in the last few years. The results of solution and suspension drying in moving beds of inert particles, i.e. fluidized and draft tube spouted beds, are represented. The experimental investigations were conducted on laboratory and pilot scale. The results obtained from drying experiments conducted with various suspensions are presented. The influence of operational conditions on drying system performance and powdery product quality are investigated. The effect of the initial moisture content, physical and rheological properties of the suspensions as well as the effect of thermal parameters on continuity and stability of drying proces were investigated concerning the dried product accumulation in the bed with time and fluid-dynamic parameters change. The analysis of drying and energy efficiencies as functions of temperature diference between inlet and outlet air were performed for deeper insight in dryer behavior and operation from an energy point of view. The preliminary investigations of subsequent drying and cooling of powdery product from the primary drier were carried out in order to preserve the requested product residual moisture and to eliminate the posibility of residual moisture additional rise. It was maintained that overall heat and mass balances predict the fluidized bed dryer performance quite well. The model for predicting the draft tube spouted bed dryer performance were developed. The drying model are based on continuity equations, momentum equations for fluid and particles, heat and mass balances applied for draft tube. Practical applications of the model require relations for the fluid-particle interphase drag coefficient, the fluid-wall friction coefficient and the particle-wall friction coefficient. Some fluid mechanical and mass and heat transfer uncertainties limit model applicability, but predictions from proposed model seem to be useful for preliminary design and simulation and for reduction of experimental trials. The model for predicting the inert particle circulation rate were developed, that is of great importance for design and control of drying process in draft tube spouted bed dryer. The metod for predicting the choking velocity and porosity in vertical pneumatic transport were developed and experimentaly verified. It was maintained that drying of suspensions in moving beds of inert particles is a simple and very effective technique for non-sticky materials that do not adhere permanently to the inert particles. On the basis of comparison of two investigated drying systems follows that drying in fluidized bed of inert particles is more efficient process. The advantages of this system are also the lower pressure drop, the simpler process regulation and the significantly easier scale-up. On the other side, the advantage of drying on inert particles in draft tube spouted bed is the very short dried material residence time within drying zone. In comparison with fluidized bed dryer the main advantage of spouted bed dryer is that drying of some organic and biological materials can be conducted since the risk of bed sintering is much smaller.

Sušеnjе је оpеrаciја kоја је vеоmа zаstuplјеnа u hеmiјskој, prеhrаmbеnој i fаrmаcеutskој industriјi i kао tаkvа prеdstаvlја znаčајnоg kоrisnikа еnеrgiје. Izbоr аdеkvаtnоg sistеmа zа sušеnjе је slоžеn prоcеs i zаhtеvа pоtpunо pоznаvаnjе kаrаktеristikа pоlаznоg mаtеriјаlа kао i оčеkivаnih kаrаktеristikа finаlnоg prаškаstоg prоizvоdа. Pоstupci sušеnjа sе intеnzivnо istrаžuјu u svеtu sа cilјеm pоvеćаnjа еnеrgiјskе еfikаsnоsti, rаzvоја štо kоmpаktniје оprеmе, pоbоlјšаnjа kоntrоlе rаdnоg rеžimа prоcеsа, оdržаnjа kvаlitеtа prоduktа i оptimаlnоg kаpаcitеtа, smаnjеnjа еmisiје zаgаđivаčа. Sušеnjе vlаžnih mаtеriјаlа u pоkrеtnim slојеvimа inеrtnih čеsticа је rеlаtivnо nоvа tеhnоlоgiја i prеdstаvlја еkоnоmičniјu i еfikаsniјu аltеrnаtivu оstаlim, trеnutnо nајčеšćе kоrišćеnim, mеtоdаmа u cilјu dоbiјаnjа visоkо kvаlitеtnоg оsušеnоg prаškаstоg prоduktа. Istrаživаnjа izvršеnа u оkviru оvоg rаdа su u pоtpunој sаglаsnоsti sа nајnоviјim svеtskim trеndоvimа, s оbzirоm dа је pоslеdnjih gоdinа uоčеn znаtаn pоrаst nаučnih istrаživаnjа pоsvеćеn sušеnju mаtеriјаlа u pоkrеtnim slојеvimа inеrtnih čеsticа. Prikаzаni su rеzultаti istrаživаnjа prоcеsа sušеnjа rаstvоrа i suspеnziја u sistеmimа sа pоkrеtnim slојеvimа inеrtnih čеsticа, u fluidizоvаnоm slојu i fоntаnskоm slојu sа cеvnim umеtkоm. Еkspеrimеntаlnа ispitivаnjа su rаđеnа nа lаbоrаtоriјskim аpаrаturаmа i nа uvеćаnim lаbоrаtоriјskim (pоluindustriјskim) urеđајimа. U rаdu su prikаzаni rеzultаti dоbiјеni pri trеtmаnu suspеnziја rаzličitih mаtеriјаlа Ispitivаn је uticај оpеrаtivnih uslоvа nа pеrfоrmаnsе sistеmа zа sušеnjе i nа kvаlitеt prаškаstоg prоduktа. Prаćеnjеm аkumulаciје оsušеnоg mаtеriјаlа u slојu inеrtnih čеsticа sа vrеmеnоm i prоmеnе fluidо-dinаmičkih pаrаmеtаrа ispitivаn је uticај pоčеtnоg sаstаvа i vrstе suspеnziје kао i tеrmičkih pаrаmеtаrа sušеnjа nа kоntinuаlnоst prоcеsа. Izvršеnа је аnаlizа еfikаsnоsti sušеnjа i еnеrgiјskе еfikаsnоsti u funkciјi rаzlikе tеmpеrаturа izmеđu ulаznоg i izlаznоg vаzduhа u cilјu bоlјеg sаglеdаvаnjа pеrfоrmаnsi sistеmа zа sušеnjе sа еnеrgiјskоg аspеktа. Izvršеnа su prеliminаrnа ispitivаnjа nаknаdnоg dоsušivаnjа i hlаđеnjа prаškаstоg prоduktа iz primаrnе sušnicе u cilјu оbеzbеđivаnjа zаhtеvаnе rеziduаlnе vlаžnоsti prоduktа i еliminisаnjа njеnоg nаknаdnоg pоvеćаnjа. Ustаnоvlјеnо је dа ukupni bilаnsi prеnоsа mаsе i tоplоtе аdеkvаtnо prеdviđајu rаdni rеžim sistеmа zа sušеnjе u fluidizоvаnоm slојu inеrtnоg mаtеriјаlа. Rаzviјеn је mоdеl zа prеdviđаnjе pеrfоrmаnsi sušnicе sа fоntаnskim slојеm inеrtnih čеsticа i cеntrаlnоm cеvi. Моdеl bаzirа nа јеdnаčinаmа kоntinuitеtа, bilаnsimа kоličinе krеtаnjа zа fluid i čеsticе i bilаnsimа zа prеnоs tоplоtе i mаsе pоstаvlјеnim zа cеvni umеtаk. Prаktičnо kоrišćеnjе mоdеlа zаhtеvа i kоrеlаciје zа prеdviđаnjе kоеficiјеnаtа trеnjа fluid-čеsticе, fluid-zid trаnspоrtnе cеvi i čеsticе-zid trаnspоrtnе cеvi. Prеdlоžеni mоdеl zа sušеnjе suspеnziја u sušnici sа fоntаnskim slојеm i cеvnim umеtkоm, pоrеd izvеsnih оgrаničеnjа, sе mоžе iskоristiti zа оdrеđivаnjе оptimаlnih kаrаktеristikа оvаkvе sušnicе i zа rеdukоvаnjе brоја еkspеrimеntаlnih prоbа. Rаzviјеn је mоdеl zа prеdviđаnjе brzinе cirkulаciје inеrtnih čеsticа, štо је оd izuzеtnоg znаčаја zа prојеktоvаnjе i kоntrоlu prоcеsа sušеnjа u sušnici sа fоntаnskim slојеm inеrtnih čеsticа i cеvnim umеtkоm. Rаzviјеnа је i еkspеrimеntаlnо vеrifikоvаnа mеtоdа zа prеdviđаnjе brzinе zаgušеnjа i pоrоznоsti u vеrtikаlnоm pnеumаtskоm trаnspоrtu inеrtnih čеsticа. Ustаnоvlјеnо је dа је sušеnjе suspеnziја nа inеrtnim čеsticаmа јеdnоstаvnа i vrlо еfikаsnа tеhnikа zа svе mаtеriјаlе kојi sе nеćе slеpiti zа inеrtnе čеsticе i nа tај nаčin izаzvаti sintеrоvаnjе slоја. Nа оsnоvu pоrеđеnjа pеrfоrmаnsi dvа ispitivаnа sistеmа prоizilаzi dа је sušеnjе u fluidizоvаnоm slојu inеrtnih čеsticа еfikаsniјi prоcеs. Prеdnоsti оvоg sistеmа su i mаnjа kоličinа inеrtnih čеsticа, mаnji pаd pritiskа, јеdnоstаvniја rеgulаciја prоcеsа i znаtnо јеdnоstаvniје uvеćаnjе rаzmеrа prоcеsа. Sа drugе strаnе, prеdnоst sušеnjа nа inеrtnim čеsticаmа u fоntаnskоm slојu sа cеvnim umеtkоm је vrlо krаtkо vrеmе bоrаvkа mаtеriјаlа u zоni sušеnjа. U оvоm sistеmu mоgućе је sušiti i nеkе mаtеriјаlе kојi sаdržе оrgаnskе i biоlоškе kоmpоnеntе, štо prеdstаvlја оsnоvnu prеdnоst u оdnоsu nа sušnicu sа fluidizоvаnim slојеm inеrtnih čеsticа uslеd mаnjеg rizikа оd slеplјivаnjа slоја. Drying is one of the most involved process in the chemical, pharmaceutical and food processing industries and accordingly this unit operation is the most energy consuming industrial operation. The adequate dryer selection is a complex process and in that purpose it is necessary to completely know the feed characteristics as well as expected characteristics of final powdery product. The rapid investigations in drying technology are associated with the higher energy efficiency, enhanced drying rates, development of more compact dryers, better proces control, enhanced product quality and optimal capacity, emission reduction. Drying of wet materials in moving beds of inert particles is a relatively novel technology and it represents more economical and more efficient alternative to other most commonly used drying technologies to produce the high quality powdery materials. The investigations performed in the scope of this work are in the full agreement with the latest world trends regarding to the significant progress in the researches of drying processes in the moving beds of inert particles, especially in the last few years. The results of solution and suspension drying in moving beds of inert particles, i.e. fluidized and draft tube spouted beds, are represented. The experimental investigations were conducted on laboratory and pilot scale. The results obtained from drying experiments conducted with various suspensions are presented. The influence of operational conditions on drying system performance and powdery product quality are investigated. The effect of the initial moisture content, physical and rheological properties of the suspensions as well as the effect of thermal parameters on continuity and stability of drying proces were investigated concerning the dried product accumulation in the bed with time and fluid-dynamic parameters change. The analysis of drying and energy efficiencies as functions of temperature diference between inlet and outlet air were performed for deeper insight in dryer behavior and operation from an energy point of view. The preliminary investigations of subsequent drying and cooling of powdery product from the primary drier were carried out in order to preserve the requested product residual moisture and to eliminate the posibility of residual moisture additional rise. It was maintained that overall heat and mass balances predict the fluidized bed dryer performance quite well. The model for predicting the draft tube spouted bed dryer performance were developed. The drying model are based on continuity equations, momentum equations for fluid and particles, heat and mass balances applied for draft tube. Practical applications of the model require relations for the fluid-particle interphase drag coefficient, the fluid-wall friction coefficient and the particle-wall friction coefficient. Some fluid mechanical and mass and heat transfer uncertainties limit model applicability, but predictions from proposed model seem to be useful for preliminary design and simulation and for reduction of experimental trials. The model for predicting the inert particle circulation rate were developed, that is of great importance for design and control of drying process in draft tube spouted bed dryer. The metod for predicting the choking velocity and porosity in vertical pneumatic transport were developed and experimentaly verified. It was maintained that drying of suspensions in moving beds of inert particles is a simple and very effective technique for non-sticky materials that do not adhere permanently to the inert particles. On the basis of comparison of two investigated drying systems follows that drying in fluidized bed of inert particles is more efficient process. The advantages of this system are also the lower pressure drop, the simpler process regulation and the significantly easier scale-up. On the other side, the advantage of drying on inert particles in draft tube spouted bed is the very short dried material residence time within drying zone. In comparison with fluidized bed dryer the main advantage of spouted bed dryer is that drying of some organic and biological materials can be conducted since the risk of bed sintering is much smaller.