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Biomimetic membranes for forward osmosis application in industrial wastewater treatment
Jasmina Korenak, 2018, doktorska disertacija

Opis: The problem of wastewater is increasing as we face tighter regulations in limiting parameters for discharge into sewers or surface waters. At the same time, the challenge is also how to upgrade existing technology and identify new appropriate technologies for purification of industrial wastewater for re-use. The optimal solution, which can give the appropriate quality of purified water at acceptable operating costs also is not straightforward. However, increasing environmental legislative demands combined with increased fresh water consumption can facilitate implementation of emerging technologies which at the current state are not fully mature. Forward Osmosis (FO) is one such recent achievement which is considered as a promising membrane process and potentially a sustainable alternative to reverse osmosis (RO) process for wastewater reclamation and sea/brackish water desalination. However, there are many limiting parameters (e.g. membrane fouling, draw solutions) in FO process that needs to be studied and improved. To reduce the membrane fouling in FO, many improvements were attempted, e.g. synthesis of different membrane materials, fabrication of membrane modules, membrane coating etc. One of the novelties in membrane development research field is biomimetic membranes incorporate in separation processes. They employ natural proteins known as AQPs (aqpourins) to regulate the flow of water, providing increased permeability and near-perfect solute rejection. Membrane surface characteristics were measured on virgin, used and cleane membrane in order to confirm the resistance to different types of industrial wastewater and sewage.
Ključne besede: biomimetic membrane, forward osmosis, industrial wastewater, reverse osmosis, textile wastewater, ultrafiltration, wastewater reuse
Objavljeno: 25.07.2018; Ogledov: 325; Prenosov: 19
.pdf Celotno besedilo (4,64 MB)

Procesi odstranjevanja antibiotikov iz bolnišničnih odpadnih vod
Severina Stavbar, 2018, doktorska disertacija

Opis: Ostanki antibiotikov in drugih zdravil, postajajo vse resnejši problem, saj jih najdemo v izpustih iz farmacevtskih in proizvodnih obratov, bolnišnic in odplakah iz čistilnih naprav. Različne študije so pokazale, da so ostanki antibiotikov prisotni v odpadnih in površinskih vodah, zadnje študije pa kažejo trend zviševanja tudi v tleh, podtalnici ter pitni vodi. Čeprav so izmerjene koncetracije v širokem koncentracijskem območju od ng/L do µg/L, so lahko nekateri razgradni produkti aktivnih snovi celo bolj toksični kot izvorna snov. Predhodne študije so pokazale, da so najvišje koncentracije antibiotikov v bolnišničnih odpadnih vodah. Za odstranitev takšnih onesnaževal pa obstoječe čistilne naprave niso primerne, saj velike količine antibiotikov ostajajo v vodi tudi po čiščenju. V doktorski disertaciji so predstavljeni trije procesi odstranjevanja teh onesnaževal iz bolnišničnih odpadnih vod. Glavni namen je bil poiskati napredne, izvedljive metode za odstranitev izbranih antibiotikov iz bolnišnične odpadne vode. V prvem delu smo se osredotočili na postopek čiščenja s sub in super-kritično oksidacijo, kjer smo preučili procesne parametre: vpliv temperature, tlaka, pretoka in časa. V drugem delu smo opravili postopek ozonacije, kjer smo spremljali učinkovitost čiščenja odpadne vode s spreminjanjem pH vzorca, različnimi odmerki ozona ter dodatek vodikovega peroksida (H2O2). V tretjem delu smo za čiščenje sintetično pripravljene bolnišnične odpadne vode uporabi aerobni reaktor, kjer smo iskali optimalen bivalni čas. Vsebnost antibiotikov smo po vsaki metodi čiščenja določali z optimiranimi LC-MS/MS analiznimi tehnikami. V zadnjem delu doktorske disertacije smo vse omenjene postopke čiščenja implementirali na realnem vzorcu bolnišnične odpadne vode. Vsebnost antibiotika v realnem vzorcu pred in po čiščenju smo določali z ekstrakcijo na trdni fazi v povezavi z optimirano LC-MS/MS tehniko. Na koncu smo izvedli še test inhibicije porabe kisika z aktivnim blatom za oksidacijo ogljika in amonija, s katerim smo poskušali ugotoviti, toksičen vpliv očiščene vode na mikrooganizme v aktivnem blatu.
Ključne besede: Antibiotiki, Bolnišnična odpadna voda, Sub-kritična oksidacija, Super-kritična oksidacija, Ozonacija, Aerobni reaktor, LC-MS/MS, Test toksičnosti
Objavljeno: 20.06.2018; Ogledov: 280; Prenosov: 51
.pdf Celotno besedilo (2,60 MB)

High-Perssure process design for polymer treatment and heat transfer enhancement
Gregor Kravanja, 2018, doktorska disertacija

Opis: The doctoral thesis presents the design of several high-pressure processes involving »green solvents« so-called supercritical fluids for the eco-friendly and sustainable production of new products with special characteristics, fewer toxic residues, and low energy consumption. The thesis is divided into three main parts: polymer processing and formulation of active drugs, measurements of transport properties form pendant drop geometry, and study of heat transfer under supercritical conditions. In the first part, special attention is given to using biodegradable polymers in particle size reduction processes that are related to pharmaceutical applications for controlled drug release. The PGSSTM micronization process was applied to the biodegradable carrier materials polyoxyethylene stearyl ether (Brij 100 and Brij 50) and polyethylene glycol (PEG 4000) for the incorporation of the insoluble drugs nimodipine, fenofibrate, o-vanillin, and esomeprazole with the purpose of improving their bioavailability and dissolution rate. In order to optimize and design micronization process, preliminary transfer and thermodynamic experiments of water-soluble carriers (Brij and PEG)/ SCFs system were carried out. It was observed that a combination of process parameters, including particle size reduction and interactions between drugs and hydrophilic carriers, contributed to enhancing the dissolution rates of precipitated solid particles. In the second part, a new optimized experimental setup based on pendant drop tensiometry was developed and a mathematical model designed to fit the experimental data was used to determine the diffusion coefficients of binary systems at elevated pressures and temperatures. Droplet geometry was examined by using a precise computer algorithm that fits the Young–Laplace equation to the axisymmetric shape of a drop. The experimental procedure was validated by a comparison of the experimental data for the water-CO2 mixture with data from the literature. For the first time, interfacial tension of CO2 saturated solution with propylene glycol and diffusion coefficients of propylene glycol in supercritical CO2 at temperatures of 120°C and 150°C in a pressure range from 5 MPa, up to 17.5 MPa were measured. Additionally, the drop tensiometry method was applied for measuring systems that are of great importance in carbon sequestration related applications. The effect of argon as a co-contaminant in a CO2 stream on the interfacial tension, diffusion coefficients, and storage capacity was studied. In the third part, comprehensive investigation into the heat transfer performance of CO2, ethane and their azeotropic mixture at high pressures and temperatures was studied. A double pipe heat exchanger was developed and set up to study the effects of different operating parameters on heat transfer performance over a wide range of temperatures (25 °C to 90 °C) and pressures (5 MPa to 30 MPa). Heat flux of supercritical fluids was measured in the inner pipe in the counter-current with water in the outer pipe. For the first time, the heat transfer coefficients (HTC) of supercritical CO2, ethane and their azeotropic mixture in water loop have been measured and compared. A brief evaluation is provided of the effect of mass flux, heat flux, pressure, temperature and buoyancy force on heat transfer coefficients. Additionally, to properly evaluate the potential and the performance of azeotropic mixture CO2-ethane, the coefficients of performance (COP) were calculated for the heat pump working cycle and compared to a system containing exclusively CO2.
Ključne besede: supercritical fluids, PGSSTM, formulation of active drugs, biodegradable polymers, transport and thermodynamic data, pendant drop method, carbon sequestration, heat transfer coefficients
Objavljeno: 28.05.2018; Ogledov: 284; Prenosov: 50
.pdf Celotno besedilo (5,51 MB)

Development of analytical methods for simultaneous identification and determination of phenolic compounds
Milena Ivanović, 2018, doktorska disertacija

Opis: The objective of this doctoral dissertation was to develop different analytical approaches for the extraction, separation, identification and quantitative determination of various phenolic compounds from different plants and their products. This dissertation is divided into the following four major segments, which, to some extent, can stand alone, but when it comes to the research, they are mutually very related: - Segment 1: Short-term (up to 24 h) and long-term (up to 1 month) stability studies of trans-caffeic acid (trans-CA) and trans-ferulic acid (trans-FA) dissolved in two organic solvents (methanol and tetrahydrofuran) and exposed to a range of storage conditions (temperature, organic solvents used, influence of daylight and UV irradiation) were performed for the first time. Gas chromatography with mass spectrometry (GC-MS) was used to study the degradation of the samples and structural identification of the degradation products. - Segment 2: The research within this segment focused on the optimization of a simple, fast and quantitative extraction method for the isolation of phenolic acids (PAs) from Slovenian red wine samples. Different extraction techniques were tested, and solid phase extraction (SPE) using HLB cartridges was selected as the optimal technique. For the identification and quantification of extracted analytes, the GC-MS method was optimized and validated. Different statistical and chemometrical tools were applied, and the wines were classified according to the Slovenian wine-growing regions and vine varieties. - Segment 3: The main goal within this research segment was the development of an ultrasound-assisted extraction (UAE) method for the isolation of different polyphenol classes from coriander fruits. Additionally, for the isolation of total PAs (free and bound), two analytical steps were applied: UAE alkaline hydrolysis and clean-up using SPE HLB cartridges. The response surface methodology (RSM) combined with a Box-Behnken experimental design (BBD) were used for the optimization of the alkaline hydrolysis and for increasing the extraction yields of the PAs. In this way, most influencing factors (temperature, sonication time and NaOH concentration) were studied as independent variables. Extracted PAs were determined using the previously optimized GC-MS method. - Segment 4: The main goal of this segment of the dissertation was to show the application of deep eutectic solvents (DESs) as a ‘green’ alternative to the conventional organic solvents for the isolation of phenolic compounds from plants such as Aronia melanocarpa (dried chokeberry) and Olea europaea (olive leaves). Different extraction techniques and instrumental methods were applied for the determination of phenolic profiles. Phenols from chokeberries were obtained through UAE. Furthermore, for the simultaneous identification and quantitative determination of 21 different phenolic compounds from Aronia melanocarpa, the HPLC-UV method was optimized and validated. On the other hand, microwave-assisted extraction (MAE) was used to improve the extraction yields of phenolic compounds from olive leave samples, which were subsequently determined by using validated HPLC-DAD-ESI-TOF-MS method.
Ključne besede: phenolic compounds, phenolic acids, extraction, GC-MS, HPLC, method optimization, deep eutectic solvents, plant material
Objavljeno: 11.04.2018; Ogledov: 422; Prenosov: 45
.pdf Celotno besedilo (5,10 MB)

Formation, characterization and application of polysaccharide aerogels
Gabrijela Horvat, 2018, doktorska disertacija

Opis: The aim of this PhD dissertation was to describe and analyze the preparation and characterization of polysaccharide aerogels and their future pharmaceutical and medical application. For the research, we used four types of polysaccharides: pectin, alginate, xanthan and guar. We used two types of pectin, high-methoxyl and low-methoxyl pectin, because of their different gelation mechanisms. The first part of the dissertation describes the preparation and characterization of pure polysaccharide aerogels. First, we prepared pectin spherical aerogels, cross-linked with three different ions, and we investigated their final properties. Later, we developed a new method for the preparation of alginate, pectin, xanthan and guar aerogels. We used only ethanol and no other cross-linkers. Ethanol was removed in the later processes of supercritical drying, and the remaining final material was thus only porous polysaccharide. By this method, we were able to prepare pure xanthan and guar aerogels. Prior to this study, xanthan and guar aerogels were prepared only as composites. Pectin aerogels prepared by the new method have amazing properties. On the other hand, alginate aerogels show poor characteristics, and thus the methods need to be optimised. We tried different alginate viscosities, different alcohols (methanol, ethanol, 1-propanol and 1-butanol), and we investigated longer (24h) and shorter (1h) gel setting times. The second part of this dissertation describes the pharmaceutical and medical applications of prepared aerogels. The release of diclofenac sodium from spherical pectin aerogels was investigated in vitro. Calcium cross-linked aerogels were not able to retain the drug, and its release was immediate. In order to achieve controlled release of diclofenac sodium, zinc ions had to be used as cross-linkers. Later, a low water-soluble drug, nifedipine, was used as a model drug for the monolithic aerogels prepared by the new method. The release of nifedipine from pectin and alginate aerogels was highly increased, compared to the crystalline drug. This result is promising for future evaluation of these materials for increasing the bioavailability of poorly water-soluble drugs. Nifedipine release from xanthan and guar aerogels was prolonged up to two weeks. This result reveals a new perspective on such materials for their potential use in medicine as implants and local drug delivery. According to these results, we then developed a new coating material for medical-grade stainless steel from xanthan and pectin. An aerogel coating was loaded with diclofenac sodium and indomethacin, and their release profiles were investigated in vitro. Electrochemical analysis and cell tests proved the safety of such materials for use in medicine. Using aerogel coatings, the drug can be introduced locally into the body; therefore, the need for intravenous, post-operational treatment is greatly reduced.
Ključne besede: polysaccharides, aerogels, supercritical drying, drug carriers
Objavljeno: 09.04.2018; Ogledov: 326; Prenosov: 77
.pdf Celotno besedilo (5,84 MB)

Optimizacija tvorbe filma premazov na vodni osnovi z uporabo elektrokemijske impedančne spektroskopije
Peter Berce, 2017, doktorska disertacija

Opis: Premazi na vodni osnovi predstavljajo pomemben segment v tehnologiji premazov in se uporabljajo kot okolju prijaznejša alternativa tradicionalnim premazom na osnovi organskih topil. Velika večina polimerov, ki služijo kot veziva v premazih so praktično netopna v vodi, zato se v premazih na vodni osnovi nahajajo v obliki termodinamsko nestabilne koloidne disperzije, ki je kinetično stabilizirana preko površinskega naboja in neionskih polarnih skupin. Zaradi te oblike je sušenje premazov na vodni osnovi bistveno bolj kompleksno kot sušenje tradicionalnih premazov na osnovi organskih topil. Najfleksibilnejši način optimizacije tvorbe filma iz premazov na vodni osnovi je z dodatkom koalescentov, t.j. organskih topil, ki nekaj časa zastajajo v suhem filmu in olajšajo deformacijo ter zlivanje oziroma koalescenco koloidnih delcev v homogeno polimerno plast. V doktorski disertaciji je predstavljen razvoj metodologije na osnovi uporabe elektrokemijske impedančne spektroskopije za študij tvorbe filma in optimizacijo koalescentov pri formuliranju premazov na vodni osnovi, hkrati pa so predstavljeni tudi rezultati vpliva koalescentov na lastnosti in stabilnost disperzije veziva. Naši rezultati kažejo, da koalescenti povzročajo nabrekanje in solvatacijo delcev veziva, obseg teh dveh pojavov pa je pogojen s hidrofilnostjo koalescentov, oziroma z njihovo sposobnostjo tvorjenja vodikovih vezi z vodo. Izkaže se, da je porast viskoznosti posledica povečanja volumskega dela delcev zaradi nabrekanja s topilom in zaradi znižane mobilnosti, ki jo prinese solvatacija. Koalescenti zaradi povečane solvatacije in sprememb lastnosti medija poslabšajo elektrostatično stabilnost, vendar hkrati izboljšajo sterično stabilizacijo, obseg obeh pojavov pa je zopet pogojen s hidrofilnostjo koalescenta. Razvili smo novo metodo na osnovi elektrokemijske impedančne spektroskopije, ki smo jo verificirali s pomočjo mikroskopije na atomsko silo. Preko spremembe obsega Warburgove difuzije testnega elektrolita tekom sušenja, smo kvantitativno spremljali proces tvorbe oziroma homogenizacije filma. S to novo metodo smo nato proučili vpliv hidrofilnosti, hlapnosti in količine koalescenta na tvorbo filma. Rezultati študije kažejo, da se hidrofilni koalescenti zadržujejo bližje površini delcev in tako omogočajo učinkovitejšo tvorbo filma. Ugotovili smo tudi, da do določene mere večja količina in nižja hlapnost koalescentov izboljšata tvorbo filma, vendar pa prevelika količina in uporaba prepočasnih koalescentov povzroča zastajanje topila in s tem dolgoročno mehčanje filma, ki ne doseže optimalne mehanske in kemijske obstojnosti. V disertaciji je tudi predstavljen primer optimizacije realnega zaščitenega premaza na vodni osnovi, kjer smo s pomočjo nove metode poiskali optimalno kombinacijo koalescentov in rezultate dobili desetkrat hitreje kot z uporabo klasičnih razvojnih postopkov. V doktorskem delu sta zajeta dva ključna znanstvena prispevka, in sicer nova metodologija za opazovanje in optimizacijo tvorbe filma pri premazih na vodni osnovi ter opredelitev in razlaga vplivov različnih koalescentov na stabilnost in lastnosti vodnih disperzij polimernih veziv.
Ključne besede: elektrokemijska impedančna spektroskopija, koalescent, premazi na vodni osnovi, stabilnost disperzije, tvorba filma
Objavljeno: 13.11.2017; Ogledov: 303; Prenosov: 63
.pdf Celotno besedilo (3,63 MB)

Pristop za celovit nadzor izpostavljenosti nevarnim snovem na delovnih mestih
Lidija Korat, 2017, doktorska disertacija

Opis: Izpostavljenost nevarnim snovem na delovnih mestih je kompleksno področje, ki zahteva interdisciplinarno obravnavo. V doktorski disertaciji je prikazan sistemski pristop, ki problematiko obravnava celovito, tako da povezuje različne discipline, tj. splošno kemijo, analitsko kemijo, kemijsko procesno tehniko, medicino in pravo, in s tem na sistematičen način omogoča celovit nadzor nad izpostavljenostjo nevarnim snovem na delovnih mestih. Metodološki pristop je zasnovan na algoritemski način, ki sestoji iz petih korakov. V prvem koraku, »Zbiranje podatkov«, so podani napotki za učinkovito zbiranje podatkov o nevarnih snoveh oz. zmeseh na delovnih mestih, zbrane so svetovne organizacije in baze podatkov, ki zbirajo in obdelujejo te podatke. V drugem koraku, »Opredelitev nevarnosti«, so navedeni načini za prepoznavanje nevarnosti, ki izhajajo iz lastnosti nevarnih snovi oz. zmesi. Tretji korak, »Ocenitev tveganja«, prikazuje postopke za celovito obravnavo dejavnikov, ki vplivajo na tveganja in prispevajo k njihovemu zniževanju, kot so psihosocialne razmere, zdravstveni nadzor, usposabljanja, delovna oprema, delovno okolje (osvetljenost, toplotno udobje, ročno premeščanje bremen, hrup, vibracije, elektromagnetna sevanja, alkohol, droge in druge psihoaktivne snovi, ustreznost hrambe in skladiščenje nevarnih snovi), meritve kemičnih škodljivosti, osebna varovalna oprema, biološki monitoring in izvajanje notranjega nadzora. V četrtem koraku, »Ukrepi za zmanjšanje tveganja«, so opredeljeni varnostni ukrepi od tistih z najvišjo prednostjo, tj. nadomestitev nevarne kemične snovi in/ali procesa z manj nevarno ali nenevarno snovjo in/ali procesom, če je to tehnično možno, do organizacijskih in individualnih ukrepov. V petem koraku, »Revizija ocene tveganja«, so podani napotki za redno obnavljanje ocene tveganja in evalvacijo napredka. Razvito metodologijo smo prikazali na primerih delavcev, ki so izpostavljeni stirenu in svincu oz. svinčevim spojinam, na celotnem ozemlju Republike Slovenije. Izsledki raziskave kažejo, da so najvišjim koncentracijam svinca izpostavljeni delavci v proizvodnji svinčevih akumulatorjev, nekateri so izpostavljeni celo avtoriziranim svinčevim spojinam. Največji koncentraciji stirena so izpostavljeni delavci pri ročnem nanašanju poliestrskih in vinilestrskih smol, ki se jim je vrednost mandljeve kisline v urinu zvišala za 30 % v primerjavi s predhodno raziskavo. Vpliv ototoksičnosti stirena in svinca je bil v vseh dejavnostih spregledan. Preliminarno smo opredelili tudi nevarnosti za delavce, ki so izpostavljeni nanodelcem. Prednost razvite metodologije je, da predstavlja splošni postopek, ki se lahko uporabi za nadzor izpostavljenosti različnim nevarnim snovem na delovnih mestih. Rezultati disertacije so uporabni za različne ciljne skupine, kot so izpostavljeni delavci, strokovni delavci s področja varnosti, odgovorne osebe, organi nadzora, vladne strokovne službe itd. Prispevajo k zmanjšanju tveganja za obolenja in poškodbe delavcev, vplivajo na znižanje verjetnosti požara in eksplozije ter na dvig ravni kemijske varnosti. Rezultati disertacije so pokazali nekatere vrzeli na zakonodajnem področju, zato bodo potencialna podlaga za oblikovanje zakonodajnih predlogov tako v Republiki Sloveniji kot v Evropski uniji.
Ključne besede: varnost in zdravje pri delu, nadzor, nevarne snovi, stiren, svinec, biološki monitoring
Objavljeno: 09.11.2017; Ogledov: 472; Prenosov: 113
.pdf Celotno besedilo (9,86 MB)

Določanje in kemometrijska analiza organskih spojinadsorbiranih na prašne delce PM10
Alen Miuc, 2017, doktorska disertacija

Opis: Namen naše raziskave je bil določanje okolju nevarnih organskih spojin adsorbiranih na prašne delce PM10. Vzorce smo odvzeli v skladu s standardom SIST EN 12341:2014. Po gravimetrijskem določanju delcev PM10 smo vzorce uporabili še za določitev kemične sestave in preučitev pomembnih sezonskih razlik v sestavi organskih snovi, ki jih vsebujejo delci PM10. V ta namen smo razvili analizno metodo za določevanje organskih spojin v ekstraktih vzorcev prašnih delcev PM10 s plinsko kromatografijo in masno spektrometrijo. S pomočjo kemometrijskih metod smo določili pomembne sezonske in lokacijske razlike sestave organskih spojin v zraku nad Mariborom. Določali smo sestavo spojin, ki označujejo onesnaženost in ugotavljali, katere spojine so antropogenega izvora. Ugotavljali smo, kako se sestava razlikuje glede na letni čas in odvzemno mesto vzorčenja. PM10 je frakcija respirabilnih prašnih delcev s premerom 10 μm ali manj. Suspendirani delci v zraku so naravnega (gozd, cvetni prah, padavine, neurja, vegetacija, vulkanski pepel...) ali antropogenega izvora (emisije industrije, prometa, sežig fosilnih goriv, biomase, kmetijstvo). Glede na izvor delce razdelimo na primarne in sekundarne. Primarni delci se sproščajo v ozračje direktno. Velik del organskih aerosolov v atmosferi je mogoče pripisati sekundarnim organskim aerosolom (SOA), ki nastajajo pri oksidaciji hlapnih organskih spojin (VOC) z atmosferskimi oksidanti kot so O3, OH• radikali in NO3• radikali. Fotokemični procesi vplivajo na kemično sestavo organskih spojin in njihove fizikalno-kemijske lastnosti kot so hlapnost, higroskopičnost ali kondenzacijsko aktivnost SOA spojin. Zakonsko predpisana 24-urna mejna koncentracija za delce PM10 je 50 μg/m3. Preseganja dnevnih mejnih vrednosti PM10 so praviloma v zimskem letnem času. Povišana raven delcev PM10 je predvsem posledica lokalnih izpustov. Dve tretjini vseh izpustov delcev PM10 v Sloveniji je posledica kurjenja lesa gospodinjstev. Raziskovalno delo zaznave in določanja spojin organskih onesnaževal vključuje 120 standardno odvzetih vzorcev prašnih delcev (standard SIST EN 12341:2014) z uporabo nizko volumskega vzorčevalnika, ter analitsko določevanje s plinsko kromatografijo in masno spektrometrijo (GC/MS). Za določanje polarnih organskih spojin smo uporabili sililiranje kot kemijsko tehniko derivatizacije. Nabor organskih spojin v ekstraktih prašnih delcev PM10 vključuje maščobne kisline, n- in izo-alkane, ftalatne estre, siloksane, sterole, sladkorje, sladkorne alkohole, dikarboksilne kisline, spojine razgradnje lignina in lesnih smol, policiklične organske ogljikovodike, organske dušikove spojine ter produkte sekundarne oksidacije monoterpenskih spojin. S pomočjo kemijske karakterizacije smo določili sezonske in lokacijske razlike merilnih mest. Za proučevanje smo uporabili kemometrijske metode kot so korelacijska analiza, metoda glavnih osi, hierarhično razvrščanje, analiza variance (ANOVA). V toplejših letnih časih prevladujejo na prašnih delcih adsorbirane biogene spojine nad antropogenimi spojinami. Pozimi prevladujejo antropogene organske spojine. Najbolj reprezentativne spojine zimskih vzorcev zraka so: levoglukozan, manozan, spojine ftalatnih estrov, spojine razgradnje ligninov in palmitinska kislina. Poleti prevladujejo derivati sladkorjev in sladkornih alkoholov. Na razlike vzorcev glede na sestavo organskih spojin najbolj vplivajo spojine PAHov, 1,3,5-trifenilbenzen, pinonska kislina, DEHP, glicin, nonanojska kislina (C9:0), ter jabolčna kislina in adipinska kislina. V številnih vzorcih je bil prisoten razpotegnjen kromatografski vrh neločene kompleksne mešanice (NKM), ki se razlikuje glede na letni čas in sestavo. Izvor NKM pozimi pripisujemo kurjenju fosilnih goriv ter izpuhov motornih vozil, poleti pa fotooksidacijskim procesom monoterpenov. Do lokacijskih razlik v sestavi organskih spojin adsorbiranih na ekstraktih vzorcev PM10 prihaja zaradi različnih antropogenih in biogenih izpustov, obremenjenosti posamezne
Ključne besede: PM10, EN 12341, prašni delci, organske spojine, GC/MS.
Objavljeno: 08.11.2017; Ogledov: 373; Prenosov: 47
.pdf Celotno besedilo (5,69 MB)

Multi-objective synthesis of company’s supply-networks based on integration of renewable resources
Annamaria Vujanović, 2017, doktorska disertacija

Opis: The aim of this doctoral dissertation was to develop a general methodology for sustainable integration of company's supply networks into nearby regional networks by i) integrating renewables, thereby increasing company's energy self-sufficiency, ii) by performing multi-objective synthesis in order to obtain economically efficient and yet environmentally benign or even unburdening solutions, and iii) to perform dynamic and stochastic synthesis under uncertainties in dynamically changing market conditions in order to obtain more reliable and realistic solutions. The research work is directly interlinked with a large-scale European meat producing company Perutnina Ptuj d.d., which is located in the heart of Slovenia. The aim of the first part was to integrate renewables into companies’ supply-networks at regional level in order to maximize the self-sufficiencies of their energy supplies. This concerns companies’ activities from the use of natural resources to supplying their final products to the customers being interlinked with their regional networks. A Mixed-Integer Linear Programming (MILP) model has been developed for the integration of both the companies’ and surrounding regional supply-networks and the utilization of different types of renewables as sources for the companies’ energy supplies. The potential renewable energy sources, which are located within companies surrounding region are solar, biomass, organic and animal wastes. The result indicates that by sufficient integration of renewables into companies’ supply networks, profitable and yet energy self-sufficient solutions can be obtained. The second part presents the multi-objective synthesis of a company’s supply-network by integrating renewables and accounting for several environmental footprints. A previously developed model for achieving energy self-sufficiency by integrating renewables into companies’ supply-networks has been extended for the evaluation of environmental impacts, such as energy, carbon, nitrogen, and water footprints. The achievement of an energy self-sufficient supply-network has been considered whilst significantly reducing environmental impacts. Direct (burdening) and indirect (unburdening) effects that form total effects on the environment are considered for the evaluation of environmental footprints. This approach identifies those alternative energy production technologies that are more profitable and environmentally more benign with significant unburdening capabilities. The results showed significant unburdening of the environment in terms of carbon and nitrogen footprints; however, higher burdening in terms of the water footprint. The third part presents a multi-objective MILP synthesis of a dynamic supply-network under uncertainty applied to the company. The previously-developed multi-objective model for achieving energy self-sufficiency by integrating renewables into companies’ supply-networks has now been extended to account for the dynamic consideration of variable supply and demand over the year, for uncertainties related to products’ demand and sun radiation, and for multi-objective optimisation, in order to obtain the most sustainable company’s supply-network. The sustainable synthesis of a company’s network is performed regarding the integration of the renewables such as biomass and other wastes, and solar energy. The obtained solutions are those reflecting maximal profit, reflecting constantly-changing dynamic market conditions, accounting for several uncertain parameters, and protecting the environment.
Ključne besede: Company's supply network, Renewables, Environmental Impacts, Dynamic synthesis, Flexibility, Multi-objective optimisation, Uncertainty
Objavljeno: 21.07.2017; Ogledov: 445; Prenosov: 70
.pdf Celotno besedilo (1,89 MB)

Ekstrakcija in separacija aktivnih spojin z nadkritično ekstrakcijo in preparativno nadkritično kromatografijo
Alejandro Bartolome Ortega, 2017, doktorska disertacija

Opis: V okviru doktorske disertacije smo predstavili koristi tehnologij s superkritičnimi fluidi v različnih industrijskih procesih. Čeprav je superkritični CO2 trenutno eden najpogosteje zastopanih superkritičnih fluidov v laboratorijskem merilu, pa je njegova prisotnost na področju industrije še vedno omejena, saj takšna vrsta tehnologije zahteva potrebe po zelo visokih investicijskih stroških. Kljub temu so procesi, kjer se uporablja superkritični CO2 preprosti, okolju prijazni, cena CO2 pa relativno nizka. Takšni procesi predstavljajo odlično alternativo organskim topilom. Postopki ekstrakcije in ločevanja zelo čistih aktivnih substanc, kot sta ksantohumol in beta-sitosterol za zahteve bodisi farmacevtske bodisi prehrambne industrije, kažejo odlično priložnost uporabe procesov s superkritičnim CO2 brez uporabe organskih topil. Doktorska disertacija je razdeljena na tri različne dele. V prvem delu smo raziskovali konvencionalne ekstrakcije in ekstrakcije s superkritičnimi fluidi iz jagod žago-listne palme. V nadaljevanju smo predstavili ter med seboj primerjali konvencionalne kromatografske tehnike s superkritično kromatografijo. Uspešno smo s pomočjo superkritične kromatografije ločili ksantohumol iz hmeljskega ekstrakta. V zadnjem delu doktorske disertacije smo predstavili različne tehnike emulgiranja in enkapsulacije. Ti procesi so zelo pomembni v prehrambni in farmacevtski indistriji, saj je večina aktivnih komponent netopna v vodi. Takšni procesi omogočajo proizvodnjo takšnih formulacij, ki se nato topijo v ustreznih medijih. Eksperimentalni del doktorske disertacije obsega ekstrakcije iz jagod žago-listne palme pri višjih obratopvnih pogojih kot so bili uporabljeni v predhodnih študijah. Ločevanje ksantohumola smo izvedli na pilotni napravi za superkritično kromatografijo, kjer smo spreminjali temperaturo, tlak, masni pretok, mobilno in stacionarno fazo. Rezultate smo nato primerjali s tistimi pridobljenimi s konvencionalnimi tehnikami. Skušali smo dokazati prednosti uporabe superkritične kromatografije pred drugimi tehnikami.
Ključne besede: superkritični CO2, superkritična ekstrakcija, superkritična kromatografija, ksantohumol, jagode žago-listne palme, beta-sitosterol, enkapsulacija
Objavljeno: 13.07.2017; Ogledov: 653; Prenosov: 91
.pdf Celotno besedilo (3,20 MB)

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