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Gotovo sve zemlje Europske unije, a i većina zemalja u tranziciji u posljednjem su desetljeću, a neke i ranije, pokrenule proizvodnju biogoriva i to biodizelskoga goriva i etanola. Na temelju pregleda brojnih rezultata istraživanja u svijetu, u ovom se radu analiziraju najvažnija svojstva biodizelskoga goriva, njegova dosadašnja primjena kao alternativnog goriva za dizel motore, te utjecaj njegova sagorijevanja na okoliš u odnosu na mineralno dizel gorivo. Kako je osnovna sirovina za proizvodnju biodizela iz obnovljivih resursa ulje uljane repice, detaljno se analizira postojeća struktura sjetve i udio uljane repice na obradivim površinama u Hrvatskoj, te realne mogućnosti proizvodnje ove kulture za neprehrambeni lanac, odnosno mogućnosti proizvodnje biodizela u Hrvatskoj., Practically all the countries in the European Union and most of the transition countries have in the last decade, and some even earlier than that, started off the production of biofuels, that is, of biodiesel fuel and ethanol. On the basis of a survey of numerous results of investigations in the world, in this work the most important properties of biodiesel fuel are reviewed, its employment to date as alternative fuel for diesel engines, and the environmental impact of its combustion as compared with that of mineral diesel fuel. Since the basic raw material for the production of biodiesel from renewable resources is the oil of oilseed rape, a detailed analysis is given of the existing structure of the crop and the percentage of the cultivable land in Croatia given over to oilseed rape, as well as the realistic opportunities for the production of this crop for the non-food chain, in other words, the opportunity for the production of biodiesel in Croatia.

Mikroalge rodova Nannochloropsis i Isochrysis predstavljaju sirovinu koja se može koristiti za proizvodnju energije. Cilj ovog rada bio je opisati uzgoj mikroalgi rodova Nannochloropsis i Isochrysis u različitim tehnološkim sustavima te laboratorijskim metodama istražiti njihove kemijske i fizikalne karakteristike za preliminarnu procjenu energetskog potencijala za proizvodnju bioplina i biodizela. Analizom uzoraka mikroalgi Nannochloropsis oculata, utvrđene su srednje vrijednosti sadržaja vode 95,28 %, sadržaja pepela 76,5 %, sadržaja masti 0,3271 %. Salinitet otopine uzoraka mikroalge N. oculata iznosio je 37,114 ppt. Utvrđena je kemijska potrošnja kisika (KPK), od ostataka mikroalgi nakon proizvodnje biodizela, koja je iznosila 1244 mg/L. Analizom uzoraka mikroalgi Isochrysis galbana, utvrđene su srednje vrijednosti sadržaja vode 95,42 %, sadržaja pepela 77,91 %, sadržaja masti 0,3395 %. Salinitet otopine uzoraka mikroalge I. galbana je iznosio 36,516 ppt. Utvrđena je kemijska potrošnja kisika (KPK), od ostataka mikroalgi nakon proizvodnje biodizela, koja je iznosila 999 mg/L. Može se zaključiti da postoji potencijal u proizvodnji biogoriva iz mikroalgi, te da je moguća integrirana kružna proizvodnja. Međutim, potrebno je optimizirati sustav proizvodnje kako bi prinosi bili što veći, a troškovi proizvodnje što manji. Nannochloropsis and Isochrysis microalgae represent a raw material that can be used for energy production. The aim of this research was to describe the cultivation of the Nannochloropsis and Isochrysis microalgae in different technological systems and to determine their chemical and physical characteristics using laboratory methods for a preliminary assessment of the energy potential for the production of biogas and biodiesel. Analysing the Nannochloropsis samples, the average values of water content was measured at 95.28 %, ash content at 76.5 %, fat content at 0.3271 % were determined. The solution salinity of the Nannochloropsis samples was measured at 37.114 ppt. The chemical oxygen consumption (COD) of microalgae residues after biodiesel production was determined, which was 1244 mg/L. Through the analysis of the Isochrysis galbana samples, the average values of water content was measured at 95.42 %, ash content at 77.91 %, fat content at 0.3395 % were determined. The solution salinity of the I. galbana samples was measured at 36,516 ppt. The chemical oxygen consumption (COD) of microalgae residues after biodiesel production was determined, which was 999 mg/L. It can be concluded that there is potential in the production of biofuel from microalgae, and that integrated circular production is possible. However, it is necessary to optimize the production system so that yields are as high as possible and production costs are as low as possible.

U ovom radu provedena je sinteza 45 polimernih aditiva na osnovi metil ili benzil metakrilata uz oktadecil, dodecil te 2-(tert-butilamino) etil metakrilat. Cilj rada bio je istražiti utjecaj različitih omjera navedenih monomera na sniženje tecišta dizelskog goriva bez drugih aditiva, smjese dizela i 10 vol. % biodizela te čistog biodizela. Polimeri su sintetizirani radikalskom polimerizacijom u otopini toluena uz 50 mas. % monomera uz Peroxan PO 70 kao inicijator. Sintetiziranim polimerima provjerila se čistoća (uspješnost uklanjanja zaostalih monomera) metodom infracrvene spektroskopije s Fourierovom transformacijom. Metodom 1H nuklearne magnetske rezonancije potvrđena je struktura polimernim aditivima. Toplinska svojstva ispitala su se metodom diferencijalne pretražne kalorimetrije. Formulacijama polimernih aditiva udjela 2000 ppm po masi u dizelu, smjesi B10 i B100 ispitana su niskotemperaturna svojstva radi utvrđivanja utjecaja različitih omjera komonomera u polimeru. Metodom diferencijalne pretražne kalorimetrije ispitan je utjecaj polimernih aditiva na temperaturu kristalizacije aditiviranih goriva te na promjenu entalpije kristalizacije. Kako bi se utvrdio utjecaj polimernih aditiva na temperaturu tecišta formulacija goriva, provedeno je mjerenje temperatura tecišta smjesa automatskom metodom po ASTM D5950. Naposlijetku se promatrao utjecaj aditiva na morfologiju i veličinu kristala n-parafina pomoću mikroskopa s polarizacijom dok se smjesa hladila postoljem s hlađenjem. Radom je utvrđeno da se najveće sniženje temperature tecišta postiže polimernim aditivima s najvećim udjelom dodecil metakrilata i najmanjim udjelom metil i benzil metakrilata. Ovi polimeri snizili su temperaturu tecišta s -18 °C neaditiviranog dizelskog goriva na -45 °C. Isti polimerni aditivi pokazali su najveće sniženje tecišta i u formulaciji B10 goriva gdje je tecište sniženo s -18 °C na -48 °C. Pripremljena je i smjesa funkcionalnog polimernog aditiva masenog udjela 2000 ppm u B100 gorivu te je toj formulaciji ispitano tecište. Toj formulaciji tecište se smanjilo s -6 °C (čisto B100 gorivo) na -12 °C. U radu nije utvrđen značajan utjecaj na tecište dizelskog goriva aditiviranim polimerom s komonomerom s aminskim članom. Utjecaj aminske skupine TBAEMA vidljiv je u promjeni morfologije kristala n-parafina u vidu smanjenja veličine kristala što može doprinijeti snižavanju temperature filtrabilnosti. In this work, the synthesis of 45 polymer additives based on methyl or benzyl methacrylate with octadecyl, dodecyl and 2-(tert-butylamino) ethyl methacrylate was carried out. The aim of the work was to investigate the influence of different proportions of the above monomers on the lowering of the pour point temperature of diesel fuel without additives, mixture of diesel and biodiesel (FAME) B10 and pure biodiesel B100. The polymers were synthesized in a toluene solution containing 50 mass percent of the monomer and with Peroxan PO 70 as initiator at 96 °C. The synthesized polymers were checked for purity (from residual monomers) by infrared spectroscopy with Fourier transformation. Thermal properties were tested by differential scanning calorimetry. Polymer additive mixtures of 2000 ppm mass in diesel, B10 and B100 were prepared to determine the influence of different comonomer contents in the polymer on the lowtemperature properties. Differential scanning calorimetry was used to investigate the influence of polymer additives on the crystallization temperature of the fuel formulations and on the enthalpy of crystallization. To determine the influence of polymer additives on the pour point temperature of fuel formulations, the pour point temperature of the mixtures was measured using the ASTM D5950 automated method. Finally, the effect of additives on the morphology and size of n-paraffin crystals was observed using a microscope with polarization while the mixture was cooled with a cooling stage. It was found that the greatest decrease in the pour point was achieved by the polymers with the highest proportion of dodecyl methacrylate and the lowest proportion of methyl and benzyl methacrylate. These polymers were able to lower the pour point from -18 °C in nonadditivated diesel fuel to -45 °C. These polymer additives showed the best effect in lowering the pour point in the formulation of B10 fuel, where the pour point was lowered from -18 °C to -48 °C. The formulations of the polymer additive in B100 fuel showed a decrease in pour point from -6 °C to -12 °C. The influence of the amine group TBAEMA can be seen in the change in the morphology of the n-paraffin crystals in the form of a decrease in crystal size, which may contribute to the lowering of the cold filter plugging point. In this work, no significant influence on the pour point of diesel fuel by the additive polymer with a comonomer containing an amine group was found.

Biodizel, alternativa fosilnom dizelu, dobiva se procesom transesterifikacije, odnosno alkoholize. Transesterifikacija je reakcija zamjene alkoksilnih skupina u kojoj jedan ester prelazi u drugi. Postojeći komercijalni procesi dobivanja biodizela uglavnom se zasnivaju na homogeno-bazno kataliziranoj transesterifikaciji biljnih ulja. Zbog niske cijene i visoke reaktivnosti najčešće se kao katalizatori primjenjuju NaOH i KOH. Nedostatak ovoga procesa je saponifikacija te neučinkovito odvajanje katalizatora iz reakcijske smjese. U zadnje se vrijeme vrlo intenzivno istražuju heterogeni katalizatori, zbog sigurne uporabe i mogućnosti njihova recikliranja. Najviše je u uporabi CaO. Enzimi kao katalizatori najnovije generacije do sada su pokazali izuzetnu aktivnost u katalitičkoj reakciji, ali zbog visoke cijene i rizika deaktivacije njihov potencijal nije iskorišten u industriji. Tipičan primjer postupka transesterifikacije s homogenim katalizatorom je Lurgijev postupak, a s heterogenim katalizatorom Esterfip-H proces. Biodiesel is an alternative to fossil diesel, obtained through the process of transesterification, i.e. alcoholysis. Transesterification is a reaction of replacement of alkoxy groups of alcohols when one ester converts to another. Existing commercial biodiesel production processes are mainly based on homogeneous base-catalyzed transesterification of vegetable oils. Due to the low price and high reactivity, NaOH and KOH are most often used as catalysts. Disadvantage of this process is saponification and ineffective separation of the catalyst from the reaction mixture. Recently, heterogeneous catalysts have been extensively researched, due to their safe use and the possibility of their recycling. CaO is most commonly used. Enzymes as catalysts have so far shown exceptional activity as catalysts, but due to their high price and risk of deactivation, they haven't been used as much in the industry. A typical example of the transesterification process with a homogeneous catalyst is the Lurgi process, and with a heterogeneous catalyst the Esterfip-H process.

Biodizel je ester masnih kiselina koji se najčešće sintetizira reakcijom transesterifikacije triglicerida (biljna ulja i životinjske masti) s alkoholom u prisustvu katalizatora. Proizvodnjom od otpadnog ulja, eliminiraju se dodatni troškovi uzgoja biljaka uljarica, štede se plodne površine i voda, izbjegava se kompeticija s hranom što može dovesti do rasta cijena i nedostatka hrane (jestiva biljna ulja) te se smanjuje nastanak otpada u prehrambenom sektoru. Struktura molekule biodizela ovisi o sirovinama od kojih se sintetizira. Masne kiseline triglicerida uglavnom su ravnolančane, stoga molekula alkohola određuje hoće li ester biti razgranat ili ravnolančan. Oblik molekule je odlučujuć za neka svojstva dizelskog goriva. Primjerice, duže ravnolančane molekule povećat će vrijednost cetanskog broja, dok će razgranati esteri sniziti tecište što će omogućiti rad pri nižim temperaturama. Cetanski broj je primarni indikator kvalitete goriva korištenog u kompresijskim motorima s unutarnjim izgaranjem. Neki biodizeli pokazuju visoke vrijednost cetanskog broja, no dokazano je kako su dulji ugljikovodični lanci u molekulama estera proporcionalno povezani s vrijednosti cetanskog broja. U tu svrhu istražuju se sinteze s višim alkoholima poput 1-heksanola. U ovom radu ispitivani su utjecaji reakcijskih parametara na iskorištenje reakcije transesterifikacije otpadnog ulja s heksanolom. Pratio se utjecaj molarnog omjera alkohol/ulje, utjecaj masenog udjela lužnatog katalizatora KOH, utjecaj reakcijskog vremena i temperature. Iskorištenje se određivalo iz 1H NMR spektra integriranjem površine pojedinih signala. Eksperimentalnim dijelom rada utvrđeno je da se najveće iskorištenje dobiva pri temperaturi od 60 °C. Veće iskorištenje reakcija je imala s molarnim omjerom alkohol/ulje 12:1. Veći suvišak alkohola ovu je ravnotežnu reakciju pomaknuo više prema produktima. Maseni udio katalizatora od w(KOH) = 3 % dao je veća iskorištenja reakcije u odnosu na w(KOH) = 1 %. Visoka iskorištenja reakcije dobila su se već nakon 2 minute, no do 15. minute iskorištenje se u prosjeku još povisilo za 1,59 % i doseglo svoj maksimum. Eksperimentalno je pokazano da na iskorištenje najviše utječu parametri maseni udio katalizatora te molarni omjer alkohol/ulje. Biodiesel fuel is a fatty acid alkyl ester, commonly synthesized via transesterification of triglycerides (vegetable oils and animal fats) with an alcohol, in a presence of a catalyst. Production of biodiesel fuel from waste vegetable oil eliminates additional costs of growing oilseed plants as a raw material, reduces the amount of waste in the food sector, preserves fertile land area and water, eliminates direct competition with food which could otherwise potentially lead to price increase and shortages of edible vegetable oils. The structure of the biodiesel molecule depends on the feedstock from which it's synthesized. The triglyceride’s fatty acids have mainly straight hydrocarbon chains, so the alcohol molecule determines if the ester will be straight-chained or branched. The molecule structure is determinant for some diesel fuel properties. For example, longer straight-chained molecules will have higher cetane number values, while branched ones will have lower pour point values and, therefore, engines will be able to perform at lower temperatures. Cetane number is the prime indicator of the fuel quality used in the internal combustion compression engines. Some biodiesel fuels show high cetane number values. It has been proven that longer hydrocarbon chains in the ester molecules are proportionately related to the cetane number value, therefore, synthesis with higher alcohols are being tested, such as 1-Hexanol. In this research, the influence of reaction parameters on the transesterification process of waste vegetable oil with 1-Hexanol was examined. The influence of the alcohol/oil molar ratio, the influence of the mass fraction of the alkaline catalyst KOH, the influence of the reaction time and temperature were monitored. The conversion was calculated from 1H NMR spectra by integrating the surface areas of specific signals. The experimental part of the research established that 60 °C is the best temperature out of given three in the reaction. 12:1 alcohol to oil molar ratio had a higher conversion because greater excess of an alcohol shifted this reversible chemical reaction more towards the products. The catalyst mass fraction of w(KOH) = 3 % gave higher reaction yields than the 1 % one. High conversions of the reaction were obtained after only 2 minutes, but by the 15th minute the conversion increased by approximately 1.59 % and reached its near maximum. It was experimentally shown that the parameters that have the greatest effect on conversion are the mass fraction of the catalyst and the alcohol to oil molar ratio.

Uporaba fosilnih goriv je vedno bolj nezaželena, saj so ta zaradi izčrpavanja zalog in njihovega prispevka k izpustom ogljikovega dioksida v okolje znana kot ne-trajnostna in dolgoročno škodljiva okolju. Ena izmed potencialno obnovljivih in ogljično nevtralnih alternativ naftnim gorivom je biodizel, pridobljen iz mikroalg. Mikroalge so celične tovarne, ki jih poganja sončna svetloba. Pretvarjajo ogljikov dioksid v potencialna biogoriva, hrano, krmo in visokovrednostne bioaktivne snovi. Ideja o uporabi mikroalg kot vira goriva ni nova, a jo danes zaradi trajnostnih razlogov jemljejo veliko resneje. Namen dela diplomske naloge je bil spremljanje porabe oziroma pretvorbe lipidov mikroalg s časom pri predhodno ugotovljenih optimalnih pogojih procesa proizvodnje biodizla. Reakcijo sem ustavljala ob različnih časih in pridobila časovno odvisne podatke. Sledila je GC-MS analiza končnega tekočega produkta reakcije. Analizirala sem tudi vsebnost intermediatov in reaktantov ob različnih časih. V programskem jeziku Matlab sem nato na podlagi pridobljenih eksperimentalnih podatkov s pomočjo implicitne Runge-Kutta formule z ODE 23 tb solverjem poskusila narediti ujemajoč matematični model. The use of fossil fuels is increasingly undesirable, as they are known as non-sustainable and long-term harmful to the environment due to depletion of reserves and their contribution to carbon dioxide emissions into the environment. The most similar potentially renewable and carbon-neutral alternative to petroleum fuels is biodiesel derived from microalgae, which meets the global needs of transport consumption. Microalgae are sunlight-driven cell factories that convert carbon dioxide to potential biofuels, foods, feeds and high-value bioactives. The idea of using microalgae as a source of fuel is not new, but it is now being taken much more seriously because of sustainability reasons. The main goal of the diploma thesis was monitoring the consumption or conversion of lipids of microalgae over time under previously determined optimal conditions of the biodiesel production process. I stopped the reaction at different times and obtained time-dependent data. GC-MS analysis of the final liquid reaction product followed. I also analyzed the content of intermediates and reactants at different times. In the Matlab programming language, I then tried to make an adequate mathematical model based on the obtained experimental data using the implicit Runge-Kutta formula with the ODE 23 tb solver.

Zbog povećanja broja stanovništva, povećala se i potreba za korištenjem fosilnih goriva. Izgaranje fosilnih goriva uzrokuje povećanje koncentracije CO2 u atmosferi, jednog od stakleničkih plinova koji imaju negativan utjecaj na okoliš. Stoga se čovječanstvo sve više okreće novim aletrnativnim biogorivima. Novija otkrića u proizvodnji biodizela, uključujući proizvodnju biodizela iz lipida mikroalgi, transesterifikacijom pomoću katalizatora ili u superkritičnim uvjetima, čine biodizel obećavajućim biogorivom i zamjenom za fosilna goriva. U radu su opisane prednosti, razlike i rizici u korištenju novih tehnologija tijekom cijelog životnog ciklusa proizvodnje i potrošnje biodizela. Due to population growth, the demand for fossil fuels has also increased. The burning of fossil fuels leads to an increase in the concentration of CO2 in the atmosphere, one of the greenhouse gases that have a negative impact on the environment. As a result, mankind is increasingly turning to new alternative biofuels. Recent discoveries in the field of biodiesel production, including the production of biodiesel from microalgal lipids, transesterification by catalysts or under supercritical conditions, make biodiesel a promising biofuel and a substitute for fossil fuels. The thesis describes the benefits, differences and risks of using new technologies throughout the life cycle of biodiesel production and consumption.

Ushbu maqolada hozirgi va kelajakda asosiy yoqilg’i bo’lib hisoblanadigan bioyoqilg’ilar haqida umumiy tushunchalar, bioyoqilg’ilarrning imkoniyatlari, ularning asosiy xomashyosi (biomassa) va uning tarkibi, bioyoqilg’ilarning turlari: boigaz, biobenzin, biokerosin, biodizel, biometanol, bioetanol, biobutanol va boshqa bioyoqilg’ilar haqida ma’lumotlar keltirilgan.

© 2020 Elsevier Ltd The increase in human consumption of plant and animal oils has led to the rise in waste cooking oil (WCO) production. Instead of disposing the used cooking oil as waste, recent technological advance has enabled the use of WCO as a sustainable feedstock for biofuels production, thereby maximising the value of biowastes via energy recovery while concomitantly solving the disposal issue. The current regulatory frameworks for WCO collection and recycling practices imposed by major WCO producing countries are reviewed, followed by the overview of the progress in biodiesel conversion techniques, along with novel methods to improve the feasibility for upscaling. The factors which influence the efficiency of the reactions such as properties of feedstock, heterogenous catalytic processes, cost effectiveness and selectivity of reaction product are discussed. Ultrasonic-assisted transesterification is found to be the least energy intensive method for producing biodiesel. The production of bio-jet fuels from WCO, while scarce, provide diversity in waste utilisation if problems such as carbon chain length, requirements of bio-jet fuel properties, extreme reaction conditions and effectiveness of selected catalyst-support system can be solved. Technoeconomic studies revealed that WCO biofuels is financially viable with benefit of mitigating carbon emissions, provided that the price gap between the produced fuel and commercial fuels, sufficient supply of WCO and variation in the oil properties are addressed. This review shows that WCO is a biowaste with high potential for advanced transportation fuel production for ground and aviation industries. The advancement in fuel production technology and relevant policies would accelerate the application of sustainable WCO biofuels.

Povećano iscrpljivanje postojećih zaliha fosilnih goriva i s time povezano pogoršanje stanja okoliša doveli su do potrebe za razvojem alternativnih, ekološki prihvatljivih i ekonomski isplativih izvora energije. Kao potencijalno rješenje tih problema javljaju se biogoriva proizvedena iz održivih sirovina, poput biljnih ulja i životinjskih masti. Biodizel se posebno ističe kao čista i učinkovita zamjena za dizel na bazi nafte. Međutim, prije upotrebe kao krajnjeg proizvoda, potrebno je postići zadovoljavajuću kvalitetu biodizela. Stoga je vrlo važan proces njegova pročišćavanja, tijekom kojeg se uklanjaju prisutni nusproizvodi i nečistoće. U ovom radu je provedeno kontinuirano pročišćavanje biodizela dobivenog transesterifikacijom pomoću metanola i uz lužnati katalizator KOH pri 60 °C. Kao sirovina za biodizel je korišteno otpadno jestivo ulje koje je osigurao licencirani sakupljač Agroproteinka d.o.o. U svrhu pročišćavanja je provedena kontinuirana ekstrakcija pri sobnoj temperaturi pomoću niskotemperaturnog eutektičkog otapala kolin-klorid/etilen-glikol u molarnom omjeru 1:2,5. Ekstrakcija se odvijala u koloni s pulzirajućim pliticama (Karrovoj koloni), a korištene su plitice jednake geometrije izrađene od dvaju različitih materijala: čelika i polietilen tereftalata obogaćenog glikolom (PETG). Ispitan je utjecaj materijala plitica na učinkovitost ekstrakcije glicerola i glicerida iz sirovog biodizela. Također je ispitan utjecaj omjera otapala i biodizela te frekvencije pulzacija plitica. Kvalitativna analiza sirovine, sirovog i pročišćenog biodizela obuhvaćala je FTIR i NMR spektroskopiju, a za kvantitativnu analizu korištena je tehnika plinske kromatografije. Increased depletion of existing fossil fuel reserves and the associated deterioration of the environment have led to the need for the development of alternative, environmentally acceptable and economically feasible energy sources. Biofuels produced from sustainable feedstocks, such as vegetable oils and animal fats, represent a promising solution to these problems. Due to its beneficial properties, biodiesel stands out as a clean and efficient substitute for petroleum-based diesel. However, before its use as a final product, it is necessary to achieve a satisfactory quality of biodiesel. Therefore, the process of biodiesel purification, during which the present by-products and impurities are removed, is essential. In this paper, continuous biodiesel purification was carried out. Biodiesel was obtained by transesterification using methanol and with the alkaline catalyst KOH at 60 °C. Waste cooking oil provided by the licensed collector Agroproteinka d.o.o. was used as feedstock. For purification, continuous extraction was carried out at room temperature using deep eutectic solvent choline-chloride/ethylene-glycol in a molar ratio of 1:2,5. The extraction took place in a reciprocating plate column (Karr column). Plates of the same geometry made of two different materials, steel and polyethylene terephthalate glycol (PETG), were used. The influence of plate material on the extraction efficiency of glycerol and glycerides from crude biodiesel was examined. The extraction efficiency was also influenced by the solvent to biodiesel ratio and the pulsation frequency of the plates. Qualitative analysis of raw material, crude and refined biodiesel included FTIR and NMR spectroscopy, and gas chromatography was applied for quantitative analysis.

U svrhu redukcije emisije ugljikovog dioksida, biogoriva se nameću kao alternativa konvencionalnim gorivima u transportnom sektoru. Biodizel je tip biogoriva dobiven iz otpada biljnog podrijetla. Radi zatvorenog ciklusa ugljikova dioksida, pokazala su pozitivan utjecaj na ukupne emisije ugljikova dioksida te imaju visoku korisnost oporabe otpada. Jedna od važnih prednosti biodizelskih goriva jest mogućnost miješanja s konvencionalnim dizelskim gorivom te njegova primjena u motorima s unutarnjim izgaranjem. Takve mješavine mogu se primjenjivati u motorima s unutarnjim izgaranjem uz minimalnu ili skoro nikakvu modifikaciju motora. Računalna dinamika fluida u kombinaciji s kemijskom kinetikom često se primjenjuje za analizu novih goriva, uključujući i biodizel. U ovom radu bit će dan kratki pregled i klasifikacija biogoriva, opisane fundamentalne jednadžbe računalne dinamike fluida te jednadžbe modeliranja izgaranje pomoću kemijskog mehanizma. Također, provedene su numeričke simulacije izgaranja nekoliko generacija biodizela unutar softvera za računalnu dinamiku fluida AVL-FIRE™. Simulacije su validirane usporedbom dobivenih podataka za izgaranje n-heptana, surogata dizelskog goriva, s eksperimentalnim podacima dobivenih od strane AVL GmbH Graz. Analizirana su četiri tipa biodizela dobivena iz sirovina različitog biljnog podrijetla. Gorivo je analizirano u četiri radne točke te u različitim udjelima mješavine dizelskog goriva i biodizela. In order to meet the reduction of carbon dioxide emissions, biofuels are imposed as an alternative to conventional fuels in the transport sector. Biofuel made from plant-derived waste, called biodiesel, has shown to positively impact total carbon dioxide emissions and have a positive environmental impact on waste recovery. One of the great advantages of biodiesel is its applicability in standard internal combustion engines when blended with conventional fuels. Such mixtures require very little or almost any additional modifications to the engines. Computational fluid dynamics combined with chemical kinetics is often employed to investigate combustion and auto-ignition properties of new fuels, including biofuels. This thesis will present a brief overview and generation classification of biofuels, describe the fundamental equations of computational fluid dynamics and the equations of modelling chemical kinetics using the chemical mechanism of fuel combustion. Additionally, numerical simulations of the combustion process of different generations of biodiesel were performed in the computational fluid dynamics software AVL-FIRE™. Simulations were verified by comparing the obtained simulation data for n-heptane, a substitute for diesel fuel, to experimental data provided by AVL GmbH Graz. Biodiesels made from four different plant-derived feedstocks were compared under four operating conditions in various diesel-biodiesel blends.

Biodizel je smjesa alkilnih estera masnih kiselina i najčešće se proizvodi iz jestivih biljnih ulja ili životinjskih masti. Smatra se čistom, biorazgradivom i netoksičnom alternativom za dizelsko gorivo. Da bi njegova proizvodnja i upotreba bila održivi, potrebno ga je sintetizirati iz nejestivih otpadnih sirovina. Time se smanjuje problem odlaganja otpada i izbjegavaju etički konflikti povezani s korištenjem prehrambenih namirnica u svrhu proizvodnje energenata. Obzirom na veliku globalnu proizvodnju i potrošnju kave, njezin otpadni talog smatra se potencijalnom sirovinom za proizvodnju biodizela zbog visokog udjela ulja te velike dostupnosti u cijelom svijetu. Tema ovog rada je sinteza biodizela iz otpadnog taloga kave. Ulje koje je sirovina za proizvodnju biodizela, dobiveno je procesom ekstrakcije iz kave Soxhlet metodom te ga je bilo potrebno pročistiti kapljevinskom ekstrakcijom s niskotemperaturnim eutektičkim otapalom kako bi se smanjio udio slobodnih masnih kiselina u samom ulju. Biodizel je proizveden iz ekstrahiranog ulja procesom transesterifikacije uz lužnati katalizator. Dobiveni biodizel pročišćen je kapljevinskom ekstrakcijom kojom je uklonjen sav zaostali glicerol u biodizelu. Tijekom rada istražen je utjecaj reakcijskih uvjeta na učinkovitost procesa te mogućnost primjene ekološki prihvatljivih otapala u procesu proizvodnje biodizela. Dobiveni biodizel namješan je s dizelskim gorivom te je odrađena fizikalno-kemijska karakterizacija uzorka. Biodiesel is a mixture of fatty acid alkyl esters and is most commonly produced from edible vegetable oils or animal fats. It is considered a clean, biodegradable and non-toxic alternative to diesel fuel. For its production and use to be sustainable, it needs to be synthesized from inedible waste feedstocks. This reduces the problem of waste disposal and avoids ethical conflicts associated with the use of food for energy purposes. Considering the large global production and consumption of coffee, its waste residue is considered a potential raw material for the production of biodiesel due to its high oil content and high availability worldwide. The topic of this paper is the production of biodiesel from waste coffee grounds. Oil was obtained from waste coffee grounds using the Soxhlet extraction method. It was purified by liquid-liquid extraction with a deep eutectic solvent in order to reduce the amount of free fatty acids in the oil itself. Biodiesel was produced from the extracted oil via the transesterification process with an alkaline catalyst. Crude biodiesel was then purified by liquid-liquid extraction, which removed all residual glycerol in the biodiesel. This paper explored the influence of reaction conditions on the process efficiency and the applicability of deep eutectic solvents in the process of biodiesel production from waste coffee grounds. Produced biodiesel was mixed with diesel fuel and the obtained mixture was physically and chemically characterized.

Jedan od razloga nekonkurentnosti biodizela fosilnom dizelskom gorivu je njegova cijena. Obzirom da ukupnu cijenu biodizela, oko 75 % čini cijena sirovine te kako bi se povećala cjenovna konkurentnost biodizela na tržištu pribjegava se jeftinijoj sirovini. Potencijalna jeftinija sirovina za proizvodnju biodizela je i otpadno ulje iz procesa rafinacije koje nastaje kao nusprodukt u proizvodnji biljnog ulja. Zadatak ovog rada bio je provesti enzimsku sintezu biodizela pomoću lipaze porijeklom iz gljive Thermomyces lanuginosus različitom kombinacijom biokemijskih reakcija koje kataliziraju lipaze (hidroliza, esterifikacija i transesterifikacija) iz otpadnog ulja iz procesa rafinacije. Na temelju udjela metilnih estera masnih kiselina u sirovom biodizelu, koji su određeni plinskom kromatografijom, procijenjena je primjerenost sirovine kao i optimalna kombinacija biokemijskih reakcija za enzimsku sintezu biodizela iz otpadnog ulja iz procesa rafinacije. Rezultati su pokazali da je dodatak pufera neophodan za provedbu reakcije i da kombinacija esterifikacije i transesterifikacije bez hidrolize rezultira većim udjelom metilnih estera masnih kiselina. One of the main reasons for low biodiesel demand is its price compared to fossil fuel price. Raw material used in the process makes up for 75% of the total price, which is why cheaper materials are being researched. Great potential is found in waste oils from refinery processes as a major by-product. The goal of this work was to carry out enzymatic synthesis of biodiesel with lipase from Thermomyces lanuginosus through different reaction paths (hydrolysis, esterification and transesterification) catalyzed by lipase enzymes and using waste oil from seed refinery process as material. Most favourable reaction conditions were assessed based on the amount of methyl ester fatty acids, determined by gas chromatography. It was found that the reaction rate greatly depends on buffer presence and its concentration and that esterification and transesterification without hydrolysis are more favourable to free fatty acids conversion to methyl ester fatty acids.