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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.

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.

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.

Proizvodnja biodizela, neotrovnog kapljevitog goriva koje svoju sve širu primjenu pronalazi kao zamjena ili dodatak dizelu fosilnog podrijetla, u zadnje vrijeme privlači sve veću pozornost. Jedan od najpoznatijih i najznačajnijih reakcijskih puteva sinteze biodizela, reakcija transesterifikacije, predmet je brojnih istraživanja pa je tako analizirana i u okviru ovog rada. Kao jedan od novih reaktorskih sustava za proizvodnju biodizela transesterifikacijom sve veći interes i primjenu pronalaze mikroreaktori. Za provedbu reakcije transesterifikacije u mikroreaktorima, kao i u ostalim reakcijskim sustavima, potrebno je odrediti optimalne reakcijske uvjete potrebne kako bi se dobili iskorištenja te udjeli metilnih estera masnih kiselina u skladu s odgovarajućim standardima. Kao polazna sirovina u proizvodnji biodizela najčešće se koriste različita ulja i masti prirodnog podrijetla, a kao rezultat procesa transesterifikacije dobiva se produkt koji sadrži komponente koje je potrebno odvojiti kako bi se dobio biodizel čistoće u skladu s odgovarajućim standardima. U okviru ovog rada, a u svrhu proizvodnje biodizela koji zadovoljava standarde, razvijen je integrirani mikrosustav u kojemu je prvo provedena reakcija transesterifikacije u mikroreaktoru, a zatim pročišćavanje biodizela u serijski povezanom mikrosustavu. Pročišćavanje je provedeno u mikroekstraktoru s niskotemperaturnim eutektičkim otapalom koje iz biodizela uklanja zaostale reaktante i dobiveni glicerol pri čemu se dobiva biodizel visoke čistoće. Enzim lipaza, koji je korišten za provedbu reakcije transesterifikacije u mikroreaktoru, imobiliziran je na magnetske nanočestice što je omogućilo njegovo zadržavanje u mikroreaktoru i posljedično olakšalo proces pročišćavanja biodizela u serijski povezanom mikrosustavu te proces učinilo ekonomski opravdanim. Inaktivacija enzima metanolom, drugim reaktantom u procesu transesterifikacije koji se u pravilu dodaje u suvišku, jedan je od osnovnih izazova provedbe procesa transesterifikacije katalizirane enzimima. Kao jedno od procesnih rješenja ovog izazova primijenjen je mikroreaktorski sustav u kojemu su kao ulazne procesne struje korišteni čisti metanol te emulzija ulja i enzima pri čemu je proizveden biodizel uz iskorištenje od 94 % uz vrijeme zadržavanja, 𝜏 = 20 min. Dodatno je razvijen i integrirani sustav spajanjem mikroreaktora s mikroekstraktorom pri čemu je proizveden biodizel uz iskorištenje od 94 % za vrijeme zadržavanja, 𝜏 = 20 min, te uz udio glicerola od 0,019 % (w/w). The production of biodiesel, a non-toxic liquid fuel that has been increasingly used as a replacement or addition to diesel of fossil origin, has recently attracted an increasing attention. One of the best known and most important reaction pathways of biodiesel synthesis, the transesterification reaction, is the subject of numerous studies and was analyzed in this paper. As one of the new reactor systems for biodiesel production by transesterification, microreactors have increased interest and application. To demonstrate transerterification reaction in microreactors, as well as in other reaction systems, it is necessary to determine the optimal reaction conditions needed in order to obtain yields and content of fatty acid methyl esters in accordance with relevant standards. As a starting material in the production of biodiesel, various oils and fats of natural origin are commonly used, and as a result of the transesterification process, a product is obtained that contains components that need to be separated in order to obtain the purity of biodiesel in accordance with relevant standards. Purpose of this work was biodiesel production of purity defined by relevant quality standards. An integrated microsystem was developed in which the transesterification reaction was firstly carried out in the microreactor leading to the purification of biodiesel in a microsystem connected in series. Purification was performed in a microextractor using a deep eutectic solvent that removes residual reactants and produced glycerol where in the same time biodiesel of high purity is obtained. Lipase, which was used to carry out the transesterification reaction was immobilized on magnetic nanoparticles, which enabled enzyme retention in a microreactor and consequently facilitated the process of purification of biodiesel integrated microsystem and made the process economically sustainable. Inactivation of the enzyme by methanol, another reactant in the transesterification process which is generally added in excess, is one of the primary challenges of enzyme-catalyzed transesterification processes. As one of the possible process solutions, a microreactor system was used in which pure methanol and emulsion of oil and enzyme were used as process inlets where biodiesel was produced with a yield of 94 % for the retention time of 𝜏 = 20 min. Additionally, an integrated system was developed by combining the microreactor with a microextractor. In this system biodiesel was produced with a yield of 94 % for the retention time of 𝜏 = 20 min, and with glycerol content of 0,019 % (w/w).

Ograničene količine fosilnih goriva i njihov nepovoljan utjecaj na klimatske promjene potaknuli su znanstvenike na traženje alternativnih izvora energije. Kao jedno od boljih rješenja tog problema pokazao se biodizel. Reakcija transesterifikacije temeljna je reakcija kojom se proizvodi biodizel. Reakcijom alkohola i triglicerida, koji su glavni sastojak masti i ulja, uz prisutnost katalizatora nastaju esteri masnih kiselina. Osim jestivih, nejestivih i otpadnih ulja koja mogu biti korištena prilikom sinteze biodizela, izbor alkohola također je prilično širok. Najviše je istražena sinteza biodizela iz metanola i etanola, ali u novije doba interes su privukli i određeni viši alkoholi. Odabrani alkohol u ovom radu je izopentanol koji reagira sa suncokretovim uljem uz prisutnost bazičnog katalizatora, kalijevog hidroksida. Pratio se utjecaj četiri reakcijska parametra na iskorištenje reakcije transesterifikacije, a to su: reakcijsko vrijeme, molarni omjer alkohola i ulja, maseni udio katalizatora i temperatura reakcije. Reakcijsko vrijeme bilo je u rasponu od 0,5 do 2,5 h, molarni omjer alkohola i ulja od 4:1 do 10:1, maseni udio katalizatora od 1 do 3 % i temperatura reakcije od 40 do 80 ˚C . Uz pomoć programskog paketa Design Expert 11 napravljen je Box-Behnkenov plan koji sadrži 29 pokusa. Iako se najčešće primjenjuje kao kvalitativna metoda, 1H NMR spektroskopija korištena je za kvantitativnu analizu tj. određivanje iskorištenja reakcije. Analizirani su brojni grafički prikazi kojima se potvrđuje ili negira poklapanje eksperimentalnih podataka s modelom dobivenim uz pomoć programskog paketa Design Expert 11. Cilj rada bio je osim određivanja utjecaja reakcijskih parametara na iskorištenje reakcije, pronaći optimalne uvjete za sintezu izopentilnih estera masnih kiselina. Programski paket nudi opciju optimiranja i ovisno o željama postavlja se maksimalna i minimalna važnost određenog reakcijskog parametra, a kao rezultat dobivaju se uvjeti sinteze i predviđeno iskorištenje koje prema HRN ISO 14214 treba minimalno iznositi 95 %. Optimiranjem procesa pokazalo se da je maksimalno moguće iskorištenje uz minimalan iznos ostalih reakcijskih parametara 98,56 %. Ukoliko se želi postići navedeno iskorištenje, potrebno je reakciju transesterifikacije provoditi 2,43 h pri temperaturi od 78,64 ˚C uz omjer alkohola i ulja 8,86:1 te maseni udio katalizatora od 2,57 %. Limited amounts of fossil fuels and their adverse effects on climate change have prompted scientists to look for alternative energy sources. Biodiesel is proven to be one of the solutions for this problem. Fundamental reaction that produces biodiesel is the transesterification reaction. Esters of fatty acids are formed in the reaction between alcohol and triglycerides, which are the main constituents of fats and oils, in the presence of catalysts. In addition to edible, inedible and waste oils that can be used in biodiesel synthesis, the choice of alcohol is also quite wide. The synthesis of biodiesel from methanol and ethanol has been the most researched, but recently certain higher alcohols have also attracted interest. The alcohol of choice in this work is isopentanol which reacts with sunflower oil in the presence of a basic catalyst, potassium hydroxide. The influence of four reaction parameters on the yield of the transesterification reaction was monitored, namely: reaction time, molar ratio of alcohol and oil, mass fraction of catalyst and reaction temperature. The reaction time ranged from 0.5 to 2.5 h, the molar ratio of alcohol and oil from 4: 1 to 10: 1, the mass fraction of catalyst from 1 to 3 % and the reaction temperature from 40 to 80 ˚C. With the help of the Design Expert 11 software package, a Box-Behnken plan, containing 29 experiments, was created. Although it is most often used as a qualitative method, 1H NMR spectroscopy was used for quantitative analysis, i.e. to determine the yield of the reaction. Numerous graphical representations were analyzed which confirm or deny the coincidence of the experimental data with the model obtained with the help of the Design Expert 11 software package. In addition to determining the influence of reaction parameters on the reaction yield, the aim of this work was to find optimal conditions for the synthesis of isopentyl fatty acid esters. The software package offers the option of optimization and, depending on the wishes, the maximum and minimum importance of a certain reaction parameter is set, and as a result the synthesis conditions and predicted yield are obtained, which according to HRN ISO 14214 should be at least 95 %. By optimizing the process, it was shown that the maximum possible yield with a minimum amount of other reaction parameters is 98.56 %. If the desired yield is to be achieved, the transesterification reaction must be carried out for 2.43 h at a temperature of 78.64 ˚C with an alcohol to oil ratio of 8.86: 1 and a catalyst mass fraction of 2.57 %.

Ograničeni resursi fosilnih goriva te onečišćenje okoliša ubrzali su pronalazak i uporabu novih alternativnih goriva. Obnovljiv izvor energije, biodizel, smatra se ekološki prihvatljivim zamjenskim gorivom za dizelske motore. Kada se proizvodi iz otpadnih sirovina iz prehrambene industrije, predstavlja i rješenje za nezbrinuti prehrambeni otpad. Primjerom takvog otpada je komina masline, koja ima veliki potencijal zbog dobrih termokemijskih karakteristika. U radu je istražena sinteza biodizela iz ulja komine masline metodom transesterifikacije pomoću homogenih bazičnih katalizatora – KOH i NaOH, te heterogenog katalizatora – CaO, u magnetskoj miješalici. KOH se pokazao kao najučinkovitiji, a CaO kao najmanje učinkovit katalizator. Dobiveni sirovi biodizel je podvrgnut pročišćavanju sa ekološki prihvatljivim niskotemperaturnim eutektičkim otapalom na bazi kolin klorida. Limited fossil fuel resources and environmental pollution have accelerated the invention and use of new alternative fuels. As a renewable energy source, biodiesel is considered an environmentally friendly alternative fuel for diesel engines. When produced from food industry by-products and wastes, it also presents a solution for unmanaged food waste. Olive pomace is one of those waste feedstocks, and it has great potential due to its good thermochemical characteristics. This paper investigates biodiesel synthesis from olive pomace oil by transesterification using two homogeneous basic catalysts – KOH and NaOH, and one heterogeneous catalyst – CaO. The highest quality biodiesel was obtained using KOH, while CaO exhibited the lowest efficiency. The obtained crude biodiesel was then subjected to purification with an environmentally friendly, low-temperature deep eutectic solvent based on choline chloride.

U ovom radu opisana je sinteza i metoda pročišćavanja tri bioaditiva dobivena reakcijom esterifikacije laurinske kiseline i odgovarajućeg alkohola. Korišteni alkoholi pri sintezi su neopentil glikol, trimetilolpropan te pentaeritrol. Sukladno korištenim alkoholima, pripravljeni bioaditivi su nazvani NPGL, TMPL te PEL. Svi bioaditivi su pročišćeni prvo ekstrakcijom, a potom i kolonskom kromatografijom. Struktura i čistoća priređenih spojeva potvrđena je korištenjem spektroskopskih metoda infracrvene spektroskopije s Fourierovom transformacijom i protonske nuklearne magnetske rezonancije. Čistoća uzoraka utvrđena je i primjenom toplinske metode diferencijalne pretražne kalorimetrije. Kako bi se ispitao utjecaj bioaditiva na niskotemperaturna svojstva dizela i biodizela, pripravljene su mješavine bioaditiva s gorivima u koncentraciji od 2000 ppm. Aditivirana goriva su analizirana metodom diferencijalne pretražne kalorimetrije te su određene točka filtrabilnosti i točka tečenja standardnim metodama EN 116, odnosno ASTM D 5950. Dodatno je ispitan i utjecaj povećanja koncentracije bioaditiva na 5000 ppm na niskotemperaturna svojstva dizela. Na temelju dobivenih rezultata može se zaključiti da bioaditivi nisu imali utjecaja na niskotemperaturna svojstva dizelskog i biodizelskog goriva. Također, u sklopu ovog rada sintetiziran je i biodizel reakcijom transesterifikacije suncokretovog ulja i alkohola metanola. Dobiveni biodizel je okarakteriziran metodama infracrvene spektroskopije s Fourierovom transformacijom i protonske nuklearne magnetske rezonancije. In this work, the synthesis and purification method of three bioadditives, obtained by the esterification reaction of lauric acid and the corresponding alcohol, is described. The alcohols used for syntheses were neopentyl glycol, trimethylolpropane, and pentaerythritol. Given the alcohols, newly synthesized bioadditives were named NPGL, TMPL, and PEL. The bioadditives were first purified by extraction, then by column chromatography. The structure and purity of the prepared compounds were confirmed by the means of spectroscopic methods, Fourier-transform infrared spectroscopy and proton nuclear magnetic resonance. The purity of the samples was also confirmed by differential scanning calorimetry. To examine the effect of bioadditives on the low-temperature properties of diesel and biodiesel, mixtures of bioadditives with fuels at a concentration of 2000 ppm were prepared. The prepared mixtures were analyzed by differential scanning calorimetry, and cold filter plugging point and pour point were determined by the standardized methods EN 116, respectively ASTM D 5950. Additionally, the influence of the concentration increase of bioadditives to 5000 ppm on the low-temperature properties of diesel was examined. Based on the obtained results, it can be concluded that bioadditives did not affect the low-temperature properties neither of diesel and biodiesel fuel. Also, as a part of this work, biodiesel was synthesized by the transesterification reaction of sunflower oil and alcohol methanol. The synthesized biodiesel was characterized by the means of Fourier-transform infrared spectroscopy and proton nuclear magnetic resonance.

Biodizel se dobiva reakcijom transesterifikacije triglicerida, najčešće iz svježih i otpadnih biljnih ulja te životinjskih masti. Predmet istraživanja ovog rada je otpadno jestivo ulje odnosno njegova predobrada s ciljem smanjenja sadržaja slobodnih masnih kiselina koje su u ulju prisutne kao posljedica njegove termičke obrade. Sirovina mora sadržavati manje od 1% slobodnih masnih kiselina da bi bila pogodna za bazično kataliziranu transesterifikaciju, u suprotnom može doći do saponifikacije te smanjene konverzije triglicerida u alkilne estere masnih kiselina. Početnoj sirovini izmjerena je gustoća, površinska napetost te međupovršinska napetost između sirovine i otapala korištenog za pročišćavanje. Sirovina je nakon toga pročišćena kolonskom ekstrakcijom u Karrovoj koloni pomoću eutektičkog otapala na bazi kalijeva karbonata. Uzorci ulja su nakon izlaska iz kolone centrifugirani kako bi se osigurala potpuna separacija ulja i otapala te im je titracijom određen kiselinski broj. Praćeni su utjecaji hidrodinamičkih uvjeta te masenog omjera ulja i otapala na efikasnost ekstrakcije. Biodiesel is produced by transesterification of triglycerides with alcohol, most commonly from fresh and waste edible oils and animal fats. The research topic of this work is waste edible oil and its pretreatment with the purpose of reducing the content of free fatty acids. During heat treatment, such as cooking, the acidity of the oil often increases. Feedstock for base-catalyzed transesterification must contain less than 1% of free fatty acids to avoid saponification and to assure good conversion of triglycerides to fatty acid alkyl esters. The feedstock was characterized by measuring its density, surface tension and interfacial tension between the oil and the solvent used for purification. It was then purified via continuous extraction in a Karr extraction column with a potassium carbonate-based deep eutectic solvent. After leaving the column, the oil samples were centrifuged to completely separate the solvent from the oil and the content of free fatty acids was determined by titration. The influences of hydrodynamic conditions and mass ratio of solvent to oil on extraction efficiency were investigated.

Otpadno jestivo ulje iz domaćinstva podvrgnuto je procesu transesterifikacije metanolom, uz KOH kao katalizator, u svrhu dobivanja biodizela. Cilj rada je provjeriti mogućnost uklanjanja vode iz biodizela, zaostale nakon ispiranja, pomoću zeolita klinoptilolita. Upotrijebljen je klinoptilolit različite veličine čestica (10 i 50 mikrona) i mase u rasponu od 0,5 do 2 grama. Određene su fizikalno – kemijske karakteristike otpadnog jestivog ulja: udio vlage, kinematička viskoznost, gustoća, kiselinski i peroksidni broj i fizikalno- kemijske karaktristike biodizela: gustoća, kinematička viskoznost te plamište. Rezultati pokazuju da se količina ostatne vode u biodizelu smanjuje povećanjem mase klinoptilolita korištenog za sušenje, ali nedovoljno da bi se zadovoljila norma o kvaliteti biodizela (ASTM D6751). Povećanjem mase klinoptilolita do četiri puta, ne uočava se proporcionalno snižavanje udjela vlage, ali pri većim udjelima klinoptilolit čestica većih dimenzija ima bolju sposobnost apsorpcije vode. Waste edible household oil was subjected to a methanol transesterification process, with KOH as a catalyst, for the purpose of obtaining biodiesel. The aim of this work is to check the possibility of removing water from biodiesel, left after rinsing, using clinoptilolite zeolite. Clinoptilolite of different particle sizes (10 and 50 microns) and weights ranging from 0.5 to 2 grams were used. Physico-chemical characteristics of waste edible oil were determined: moisture content, kinematic viscosity, density, acid and peroxide number and physico-chemical characteristics of biodiesel: density, kinematic viscosity and flash point. The results show that the amount of residual water in biodiesel decreases with increasing mass of clinoptilolite used for drying, but not enough to meet the biodiesel quality norm (ASTM D6751). By increasing the mass of clinoptilolite up to four times, no proportional decrease in the moisture content is observed, but at higher proportions clinoptilolite particles of larger dimensions have a better ability to absorb water.

U suvremenom svijetu zbog rastućih problema s okolišem dolazi do potrebe za korištenjem obnovljivih izvora energije u svakodnevnom životu i industriji. Zbog toga se nad klasičnim izvorima energije dobivenim iz fosilnih izvora nadmeće biodizel, koji se sintetizira reakcijom transesterifikacije alkohola i masti/ulja biljnog ili životinjskog porijekla, uz prisutnost katalizatora. U ovom diplomskom radu ispitan je utjecaj reakcijskih parametara na iskorištenje reakcije između propanola i suncokretovog ulja, uz KOH kao katalizator. Ispitano je četiri parametra: temperatura reakcije, vrijeme provedbe reakcije, maseni udio katalizatora i molarni omjer propanol:suncokretovo ulje. Najveće postignuto iskorištenje iznosilo je 99,79 % pri temperaturi od 60 °C, razdoblju od 2 h, masenom udjelu katalizatora od 1 mas. %, te omjeru propanol:ulje u iznosu od 10:1. Dizajniranju eksperimenta prethodila su 3 preliminarna pokusa, gdje su vrijednosti temperature bile od 40 do 80 °C, vremena od 1 do 3 h, omjera propanol:ulje od 6:1 do 10:1 i masenog udjela katalizatora od 1 do 3 mas. %. Planiranje eksperimenta i statistička obrada provedeni su u programskom paketu Design Expert. Nakon provedenih eksperimenata, provedena je optimizacija procesa transesterifikacije, s ciljem postizanja iskorištenja većeg od 95 %. Zbog toga se težilo što kraćem vremenu reakcije, nižoj temperaturi, manjem omjeru propanola i suncokretovog ulja, te manjem masenom udjelu katalizatora. Ovisno o tome kolika je zadana važnost pojedinog cilja (1-5), dobiveno je tri slučaja s različitim optimalnim uvjetima. Odabrani optimalni uvjeti iznosili su: temperatura 40,00 °C, vrijeme 2,42 h, omjer propanol:ulje 9,53:1, maseni udio katalizatora 1 mas. % pri čemu predviđeno iskorištenje iznosi 96,81 %. SUMMARY In the modern world, due to growing environmental problems, there is a need to use renewable energy sources in everyday life and industry. Therefore, biodiesel, which is obtained by the transesterification reaction of alcohol and fats/oils of vegetable or animal origin, with the presence of a catalyst, competes over classical energy sources obtained from fossil sources. In this thesis, the influence of reaction parameters on the yield of the reaction between propanol and sunflower oil, with KOH as a catalyst, was investigated. Four parameters were examined: reaction temperature, time of reaction, mass fraction of catalyst and molar ratio of propanol:sunflower oil. The highest conversion of 99.79 % is achieved at the temperature of 60 °C, reaction time of 2 hours, propanol:oil ratio in the amount of 10:1 and the mass fraction of catalyst 1 wt. %. The design of the experiment was preceded by 3 preliminary experiments, where the temperature values were from 40 to 80 °C, time from 1 to 3 hours, propanol:oil ratio from 6:1 to 10:1 and a mass fraction of catalyst from 1 to 3 wt. %. Experiment planning and processing statistics were performed in the Design Expert software package. After the experiments, the optimization of the transesterification process was made, with the aim of achieving the highest possible conversion. Therefore, we strived for the shortest possible reaction time, lower temperatures, lower ratio of propanol and sunflower oil, and lower mass fraction of catalyst. Depending on the given importance of each goal (1-5), three cases with different optimal conditions were obtained. The selected optimal conditions were: temperature 40,00 °C, time 2,42 h, propanol:oil ratio 9,53:1, mass fraction of catalyst 1 wt. %, where the predicted yield is 96,81 %.

Ozbiljna briga za okoliš vezana uz korištenje goriva fosilnog podrijetla podigla je svijest o potrebi za alternativnim čistim gorivima. Biodizelsko gorivo smatra se čistom, biorazgradivom i netoksičnom alternativom za dizelsko gorivo. Obzirom na veliku globalnu proizvodnju i potrošnju kave, otpad od kave predstavlja potencijalnu nejestivu sirovinu za proizvodnju biodizela zbog visokog udjela ulja te dostupnosti u cijelom svijetu. U ovom radu istražena je izravna, takozvana in situ transesterifikacija kojom se proizvodi biodizel iz taloga kave bez potrebe za prethodnom ekstrakcijom ulja i postupcima esterifikacije. In situ transesterifikacija provedena je posredstvom metanola i lužnatog konvencionalnog homogenog te nekonvencionalnog heterogenog katalizatora u magnetskoj miješalici i Soxhlet aparaturi. Nadalje, ovaj rad omogućuje uvid u usporedbu nekonvencionlne i konvencionalne reakcije transesterifikacije. Prilikom provedbe konvencionalne metode ulje je ekstrahirano Soxhlet metodom pomoću n-heksana te zatim pročišćeno niskotemperaturnim eutektičkim otapalom na bazi kalijevog karbonata. Sinteza je provedena uz kalijev hidroksid kao katalizator, a dobiveni sirovi biodizel pročišćen je niskotemperaturnim eutektičkim otapalom na bazi kolin klorida. Serious environmental concerns regarding the use of fossil-based fuels have raised awareness about necessity of alternative clean fuels. Biodiesel fuel is considered a clean, biodegradable and non-toxic alternative for diesel fuel. Given the large global production and consumption of coffee, coffee waste is a potential non-edible feedstock for biodiesel production due to its high oil content and availability worldwide. In this paper, direct, so-called in situ transesterification by which biodiesel is produced from coffee grounds without the need for prior oil extraction and esterification processes was investigated. In situ transesterification was performed using methanol and an alkaline conventional homogeneous and unconventional heterogeneous catalyst in a magnetic stirrer and Soxhlet apparatus. Furthermore, this paper provides insight into the comparison of unconventional and conventional transesterification reactions. When carrying out the conventional method, the oil was extracted by the Soxhlet method using n-hexane and then purified with a potassium carbonate-based deep eutectic solvent. The synthesis was carried out with potassium hydroxide as a catalyst and the obtained crude biodiesel was purified with a choline chloride based deep eutectic solvent.

Kako su količine fosilnih goriva ograničene,a sama goriva štetna za okoliš, preporuča se prelazak na obnovljive izvore energije, između kojih je i biodizel. Biodizel je danas sve popularnije gorivo zbog svoje biorazgradivosti, niske emisije štetnih plinova, manjeg zagađenja okoliša i netoksičnosti. Najčešće se proizvodnja biodizela odvija procesom transesterifikacije raznih ulja i masti uz metanol u kotlastim reaktorima te uz prisustvo kiselina, lužina ili enzima kao katalizatora. Cilj proizvodnje je dobiti što čišći primarni produkt,koji se može odmah koristiti kao gorivo sa što manje nusprodukta kako bi se izbjegli često vrlo skupi procesi pročišćavanja. Kako bi proces proizvodnje bio što uspješniji, potrebno je kontinuirano pratiti i analizirati produkte reakcije. Iako već postoje razne metode analize biodizela i glicerola, svakodnevno se istražuju nove metode čiji je glavni cilj da budu što jednostavnije, preciznije i brže. U ovom radu, biodizel je sintetiziran enzimatski kataliziranom transesterifikacijom korištenjem suncokretovog ulja i metanola kao supstrata. Tijekom procesa praćena je koncentracija nastalog glicerola kao jednog od pokazatelja uspješnosti procesa. Prvo je određena koncentracije estera masnih kiselina – biodizela plinskom kromatografijom na temelju čega je iz stehiometrije reakcije transesterifikacije izračunata teoretska koncentracija nastalog glicerola. Izračunata koncentracija glicerola je uspoređena s koncentracijom glicerola dobivenom analizom standardnim postupcima na UV-VIS spektrofotometru i plinskom kromatografu. Kako niti jedna od metoda nije dala zadovoljavajuće rezultate tj. obje analize pokazale su značajna odstupanja od teorijske vrijednosti koncentracije glicerola, kao zamjenska analitička metoda provedena je analiza na NIR spektrometru. Analiza na NIR spektrometru je provedena na dva načina, off-line iz uzorka prikupljenih tijekom provedbe procesa transesterifikacije te on-line na način da se koncentracija glicerola određivala kontinuirano prolaskom reakcijske smjese kroz protočnu kivetu NIR spektrometra. Od svih analiziranih metoda mjerenja koncentracije glicerola, NIR spektroskopija je pokazala najveće podudaranje s teoretskom, izračunatom koncentracijom glicerola. As the amount of fossil fuels is limited and the fuel itself is harmful to the environment, it is recommended to switch to renewable energy sources, including biodiesel. Biodiesel is an increasingly popular fuel today due to its biodegradability, low emissions, less environmental pollution and non-toxicity. Most often, the production of biodiesel takes place by the process of transesterification of various oils and fats with methanol in batch reactors, with the addition of acids, bases or enzymes as catalysts. The goal of production is to get the primary product as pure as possible, which can be used immediately as a fuel with small amount ofby-products as possible in order to avoid often very expensive purification processes. To make production process as successful as possible, it is necessary to continuously monitor and analyse the reaction products during the process. Although there are already various methods of analysis of biodiesel and glycerol, new methods are being researched every day, the main goal of which is to be as simple, precise and fast as possible. In this work biodiesel was synthesized by enzymatically catalysed transesterification using sunflower oil and methanol as substrates. During the process, the concentration of glycerol, as one of the indicators of the success of the process, was monitored. At the very beginning, an analysis of the fatty acid esters concentration using gas chromatography was performed from which the theoretical value of the glycerol concentration was calculated. The calculated glycerol concentration was compared with the glycerol concentration obtained by analysis using standard methods on a UV-VIS spectrophotometer and by the gas chromatography. Because neither of the methods gave satisfactory results, meaning both analyses showed significant deviations from the theoretical value of glycerol, the analysis on NIR spectrometer was proposed. During the synthesis reaction, the analysis of biodiesel concentration was performed in such a way that samples were taken at certain time intervals for the off-line analysis and on-line in such a way that the concentration was determined continuously by screening the reaction mixture which was passing through a flow cell of the NIR spectrometer. The NIR spectroscopy method proved to be the best, with the greatest agreement of the measured glycerol concentration with the theoretically calculated concentration.

U novije vrijeme sve se više zaliha fosilnih goriva nekontrolirano iscrpljuje, a različiti ekonomski, gospodarski i politički interesi suverenih država, samo su dodatni faktori koji su utjecali na sve veća ulaganja u istraživanja alternativnih goriva u svrhu povećanja ekološke svijesti. Biogoriva, osobito biodizel, ističu se kao prikladno rješenje koje odgovara zahtjevima globalnog tržišta, održivog razvoja i postizanja zadanih ušteda. Biodizel se definira kao metilni ili etilni ester viših masnih kiselina proizveden raznim procesima među kojima se ističu mikroemulzifikacija, piroliza i transesterifikacija. Potonji proces je ujedno i najrašireniji zbog visoke učinkovitosti, manjih proizvodnih troškova i velike brzine reakcije. Kao sirovine za proizvodnju biodizela transesterifikacijom koristi se široki spektar proizvoda poput jestivih i/ili otpadnih ulja i masti te alge i jantrofa koji poboljšavaju svojstva biorazgradivosti i netoksičnosti, a biodizel proizveden iz ovih sirovina odlikuju niže emisije stakleničkih plinova. Stoga se biodizel proizveden transesterifikacijom iz ovih izvora smatra i ekološki prihvatljivim. Kako bi se odvila reakcija transesterifikacije između ulja/masti i alkohola, najčešće metanola, potreban je katalizator. Uporaba enzima tj biokatalizatora, posebice enzima lipaze porijeklom iz Thermomyces lanuginosus, pokazala se obećavajućom jer su enzimi specifični, kataliziraju reakcije u kojim sudjeluju brojni supstrati, selektivni su, posjeduju visoku aktivnost u blagim eksperimentalnim uvjetima čime njihova primjena rezultira manjom potrošnjom energije u odnosu na kiselo ili bazno katalizirane reakcije transesterifikacije. Učinkovitosti procesa transesterifikacije može pridonijeti i upotreba mikroreaktorskih sustava, odnosno reaktora u mikroskopskom mjerilu. U usporedbi s makroskopskim reaktorskim sustavima, primjena mikroreaktora omogućuje bolji prijenos tvari i topline, što je posljedica velikog omjera površine i volumena samog mikroreaktora, za provedbu reakcije potrebne su manje količine reaktanata i katalizatora što rezultira i manjom količinom otpadnih struja, a samim time i manjim utroškom energije. Povoljnija hidrodinamika sustava, laminaran tok i učinkovito miješanje procesnih struja vode k povećanju brzine kemijske reakcije. U ovom radu provedena je transesterifikacija otpadnog jestivog ulja uz enzim lipazu u mikroreaktoru širine kanala 500 μm s dva ulaza i dva izlaza, a praćene su veličine značajne za uspješnu provedbu procesa (konverzija, vrijeme zadržavanja i aktivnost enzima). Maksimalna konverzija X = 32,28 % postignuta je pri najdužem retencijskom vremenu (τ = 30,63 min) za sustav u kojemu je transesterifikacija otpadnog ulja provedena uz komercijalni enzim suspendiran u puferu. In recent years, more and more fossil fuel stocks have been uncontrollably depleted and the differing economic and political interests of sovereign countries are merely additional factors that have led to increasing investment in alternative fuel research with the purpose of increasing environmental awareness. Biofuels, especially biodiesel, stand out as a suitable solution that meets the demands of the global market, sustainable development as well as achieving the set savings. Biodiesel is defined as the methyl or ethyl ester of higher fatty acids produced through various processes such as microemulsification, pyrolysis and transesterification. Tranesterification is the most widespread due to its high efficiency, lower production costs and high reaction speed. As a raw material, it offers a wide range of products such as edible and / or waste oils and fats as well as algae and amber, which improve biodegradability, non-toxicity and lower greenhouse gas emissions. Therefore, biodiesel is produced by transesterification from these sources and is environmentally friendly. In order to carry out the transesterification reaction between oil / fat and alcohol, most commonly methanol, a catalyst is required. The use of enzymes, i.e. biocatalysts, especially lipases from Thermomyces lanuginosus, has proven to be very promising as they are very specific with the recognition of numerous substrates, selective and they show high activity in mild experimental conditions, which reduces energy consumption relative to acidic or base catalyzed reactions. The efficiency of the process is also contributed by the microreactor system, i.e. the microscopic scale reactors. Comparing micro- and macroscopic systems, microreactors enable better mass and heat transfer, which is due to the large surface-to-volume ratio of the microreactor itself, requires less reactants and catalysts to effect the reaction, resulting in less waste streams and, over time, lower energy consumption. It is also noticed that more favorable hydrodynamics of the system, laminar flow and effective mixing of currents are increasing the rate of chemical reaction. In this work the transesterification of waste edible oil with lipase enzyme in a 500 μm channel microreactor with two inputs and two outputs was carried. The sizes important for successful process implementation (conversion, retention time, enzyme activity) were monitored as well. A maximum conversion of X = 32.28% was achieved at the longest retention time (τ = 30.63 min) for a system in which transesterification of waste oils was carried out with a commercial enzyme suspended in buffer.

Biodizel je obnovljivo dizelsko gorivo koje se može proizvesti iz obnovljivih bioloških izvora poput biljnih ulja ili životinjskih masti. Procesom transesterifikacije između butanola i biljnih ulja dobiva se butilni ester viših masnih kiselina (FABE). Biodizel ima višu točku izgaranja od mineralnog dizela što omogućava veću sigurnost pri rukovanju i upotrebi, biorazgradiv je, netoksičan, i ima odličnu mazivost što osigurava duži vijek trajanja motora. Klasičnim postupkom uklanjanja glicerola i alkohola iz reakcijske smjese stvaraju se velike količine otpadne vode koju je potrebno obraditi prije ispuštanja u okoliš. Iz tog se razloga istražuju nove metode pročišćavanja kako bi se smanjio negativan utjecaj na okoliš i ostvarile financijske uštede. U ovom radu provedena je sinteza biodizela (FABE) iz suncokretovog ulja s konverzijom većom od 95 % pri čemu se dobiveni produkt obrađivao s ultrafiltracijskim membranama. Ispitivala se mogućnost uklanjanja alkohola i glicerola iz reakcijske smjese. Za analizu uzoraka korištene su IR spektroskopija, 1H NMR i termogravimetrijska analiza. Od osnovnih fizikalno-kemijskih karakteristika određeni su indeks refrakcije i viskoznost reakcijske smjese te pojedinačnih komponenata. Ispitane UF membrane nisu pokazale zadovoljavajuću separaciju što ukazuje na potrebu daljnjeg istraživanja, odnosno dodatne selekcije membrana. Biodiesel is a renewable diesel fuel that can be produced from renewable biological sources such as vegetable oils or animal fats. The transesterification process between butanol and vegetable oils yields the butyl ester of higher fatty acids (FABE). Biodiesel has a higher combustion point than mineral diesel for greater handling and handling safety; it is biodegradable, non-toxic, and has excellent lubricity for longer engine life. The classic process of removing glycerol and alcohol from the reaction mixture creates large amounts of waste water that must be treated before being discharged into the environment. For this reason, new treatment methods are being explored in order to reduce the negative environmental impact and achieve financial savings. In this work, the synthesis of biodiesel (FABE) from sunflower oil with a conversion greater than 95% was performed whereby the resulting product was treated with ultrafiltration membranes. The possibility of removing alcohol and glycerol from the reaction mixture was examined. IR spectroscopy, 1H NMR and thermogravimetric analysis were used to analyze the samples. The basic physicochemical characteristics were determined by the refractive index and the viscosity of the reaction mixture and the individual components. The UF membranes tested did not show satisfactory separation, which indicates the need for further investigation, i.e. additional membrane selection.

Biodizel je ester viših masnih kiselina i nižih alkohola koji uz konvencionalno dizelsko gorivo pronalazi primjenu u dizelskim motorima. Mineralni dizel i biodizel se namješavaju u različitim omjerima kako bi se dobila ekološki prihvatljivija goriva s boljim svojstvima u odnosu na polazne sastavnice – bolju mazivost od čistog dizela te višu toplinsku vrijednost i nižu viskoznost od biodizela. Butilni esteri viših masnih kiselina (FABE) se proizvode iz butanola i biljnih ulja reakcijom transesterifikacije pri čemu se radi veće konverzije butanol dodaje u suvišku. U ovom radu provedena je sinteza biodizela (FABE) iz suncokretovog ulja te je ispitan utjecaj molekulskih međudjelovanja na svojstva mješavina dizela, biodizela i butanola u različitim udjelima. Dobivenim mješavinama su normiranim metodama određeni gustoća, mazivost, kinematička viskoznost i temperatura filtrabilnosti. Dodatno su još provedena ispitivanja korištenjem termogravimetrijske analize (TGA), diferencijalne pretražne kalorimetrije (DSC), infracrvene spektroskopije s Fourierovom transformacijom (FTIR) te ispitivanjem kontaktnog kuta i reoloških svojstava. Biodiesel is ester of higher fatty acids and lower alcohols that is, along with conventional diesel fuel, used in diesel engines. Mineral diesel and biodiesel are blended in different ratios to obtain environmentally acceptable fuels with better properties in regards to raw materials – better lubricity from pure diesel and higher heating value and lower viscosity from biodiesel. Fatty acid butyl esters (FABE) are produced using butanol and vegetable oil in transesterification whereby excess of butanol is used to accomplish higher conversion rate. In this work, biodiesel (FABE) is synthesized from sunlower oil and effect of molecular interactions on properties of mineral and renewable diesel fuel blends are examined. Using standardized methods, density, viscosity, cold filter plugging point and lubricity are analyzed for prepared blends. Additional examinations are made using termogravimetric analysis (TGA), differential scanning calorimetry (DSC), Fourier Transform Infrared Spectroscopy (FTIR) and analysis of contact angle and rheological properties.

Membranski procesi su separacijski procesi kojima se pomoću membrane ulazna struja odvaja na retentat (dio ulazne struje koji se zadržao na membrani) i permeat (dio ulazne struje koji je prošao kroz membranu). Odvajanje je temeljeno na sposobnosti membrane da jednu komponentu iz ulazne smjese lakše transportira, u odnosu na druge komponente, što proizlazi iz fizikalnih i kemijskih svojstava membrane i komponente koju prožima. U ovome radu provedena je membranska ultrafiltracija smjese etilnih estera viših masnih kiselina, etanola, suncokretovog ulja i glicerola. Za razdvajanje korištene su 3 vrste polimernih membrana – PT membrane proizvedene od polietersulfona s graničnom molekulskom masom (MWCO) od 5000 Da te poliamidne membrane GK s MWCO od 3000 Da i GH s MWCO od 2000 Da. Esteri viših masnih kiselina (biodizel) proizvedeni su reakcijom transesterifikacije, a cilj je bio izravno iz reakcijske smjese izdvojiti samo etilne estere. Najučinkovitija membrana za uklanjanje glicerola pokazala se PT membrana pri radnom tlaku od 6 bara (6×105 Pa) koja je uklonila 38,3 % glicerola i 32,5 % etanola iz smjese. Za uklanjanje etanola iz smjese najučinkovitija je bila GK membrana također pri radnome tlaku od 6 bara koja je uklonila 57,8 % etanola iz smjese i 8,2 % glicerola. Membrane separation is a process in which the membrane separates the inlet stream on retentate (part of the inlet stream retained on the membrane) and the permeate (part of the inlet stream that passed through the membrane). Separation is based on the ability of the membrane to transport one component from the inlet stream more easily than other components based on the physical and chemical properties of the membrane and the permeating component. In this thesis a membrane ultrafiltration separation of fatty acid ethyl esters from mixture of ethanol, sunflower oil and glycerol, was conducted. Three types of polymer membranes were used: PT membrane produced by polyethersulfone with a molecular weight cut-off (MWCO) of 5000 Da and two polyamide membranes, GK with a MWCO of 3000 Da and GH with a MWCO of 2000 Da. Fatty acid ethyl ester (biodiesel) were produced by transesterification and the goal was to isolate them directly from the mixture after the reaction. The most efficient membrane for glycerol removal is PT membrane working at 6 bar (6×105 Pa). It reduced the concentration of glycerol by 38,3 % and ethanol by 32,5 % compared to starting mixture. The most efficient membrane for reducing the concentration of ethanol from the starting mixture is GK membrane under the same conditions (6 bar) and reduction of 57,8 % of ethanol and 8,2 % of glycerol, compared to concentration in starting mixture, was achieved.