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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.

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.

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.

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).

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.

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.

Biodizel je smjesa metilnih estera masnih kiselina (eng. Fatty Acid Methyl Esters, FAME) nastalih transesterifikacijom biljnih ulja i/ili životinjskih masti s metanolom, uz prisustvo katalizatora. Biodizel se može proizvoditi kemijskim i enzimskim putem. Cilj ovoga rada bio je u enzimski kataliziranoj reakciji transesterifikacije sintetizirati biodizel te procijeniti energetsku efikasnost procesa. Za sintezu je korišteno svježe jestivo suncokretovo ulje i metanol te Amano lipaza podrijetlom iz bakterije Burkholderia cepacia gdje je aktivnost enzima bila 250 i 750 U/g reakcijske smjese, a različite koncentracije i pH vrijednosti fosfatnog (200 mmol/L, pH 7 i 8) i univerzalnog Britton-Robinsonovog pufera (40 i 200 mmol/L, pH 10). Reakcije su provođene u trajanju od 24 sata, a uzorci biodizela su uzimani nakon 1, 2, 3, 6, 12 i 24 sata. Udio FAME određena je plinskom kromatografijom. Optimalni uvjeti za provedbu enzimske sinteze biodizela (udio metilnih estera masnih kiselina u sirovom biodizelu veći od 99 %) uz B. cepacia lipazu tijekom prvog sata sinteze su 50 °C, molarni omjer ulja i metanola 1:3,4, aktivnost lipaze od 250 U/g reakcijske smjese uz 200 mmol/L Britton-Robinsonov pufer pH 10. Enzimski katalizirana transesterifikacija se pokazala energetski efikasna (EROEI > 1), uz omjer dobivene i utrošene toplinske energije od 1,16. Biodiesel is a mixture of Fatty Acid Methyl Esters (FAME) formed by transesterification of vegetable oils and / or animal fats with methanol, in the presence of a catalyst. Biodiesel can be produced chemically and enzymatically. The aim of this work was to synthesize biodiesel in an enzymatically catalyzed transesterification reaction and to evaluate the energy efficiency of the process. For synthesis is used fresh edible sunflower oil, methanol and Amano lipase originating from Burkholderia cepacia at activity loads of 250 and 750 U/g of reaction mixture, whereas were used different concentrations and pH values of phosphate (200 mmol / L, pH 7 and 8) and universal Britton – Robinson's buffer (40 and 200 mmol/L, pH 10). Reactions were performed for 24 hours, and biodiesel samples were taken after 1, 2, 3, 6, 12, and 24 hours. The proportion of FAME was determined by gas chromatography. Optimal conditions for the implementation of enzymatic synthesis of biodiesel (content of fatty acid methyl esters in crude biodiesel greater than 99%) with B. cepacia lipase during the first hour of synthesis are 50 °C, molar ratio of oil and methanol 1: 3.4, lipase activity load of 250 U/g of the reaction mixture with 200 mmol/L Britton-Robinson buffer pH 10. Enzyme-catalyzed transesterification proved to be energy efficient (EROEI > 1), with an energy output to energy input ratio of 1.16.

Istražena je mogućnost primjene otpadnih ljuski od jaja kao heterogenog katalizatora za proizvodnju biodizela iz sirovina različitog porijekla. Usitnjene ljuske od jaja kalcinirane su 2 sata pri 1000 °C. Provedena je simultana termogravimetrijska i diferencijalna toplinska analiza usitnjenih ljuski od jaja prije i nakon kalciniranja, a struktura je određena rendgenskom difrakcijom. Ljuske od jaja su čisti kalcijev karbonat koji žarenjem prelazi u čisti kalcijev oksid. Dobiveni kalcijev oksid korišten je kao katalizator u procesu kemijske transesterifikacije ulja i masti pri definiranom omjeru. Produkti reakcije transesterifikacije karakterizirani su infracrvenom spektroskopijom s Fourierovom transformacijom te spektroskopijom protonske nuklearne magnetske rezonance. Na temelju dobivenih rezultata može se zaključiti da vrsta i sastav sirovine kao i metoda provedbe reakcije u velikoj mjeri utječu na konverziju ulja i masti u biodizel. Katalizator se pokazao najučinkovitijim pri korištenju ulja otpadnog taloga kave s visokim udjelom slobodnih masnih kiselina kao sirovine.

Lipidi izolirani iz biomase mikroalgi Nannochloropsis sp. predstavljeni su kao perspektivna sirovina za proizvodnju biodizela. U ovom radu proveden je fototrofni šaržni uzgoj s pritokom supstrata u otvorenom sustavu na izvornoj f/2 podlozi uz dodatak natrijevog bikarbonata te fototrofni šaržni uzgoj s pritokom supstrata u barbotirajućoj koloni na izvornoj f/2 podlozi bez dodatnog izvora ugljika. Tijekom uzgoja praćene su promjene udjela proteina, ugljikohidrata i lipida u izdvojenoj biomasi kao i sastav pigmenata te profil masnih kiselina u ukupnim lipidima. Utvrđeno je da u periodu smanjene koncentracije fosfora, metabolizam mikroalge se usmjerava prema akumulaciji lipida i ugljikohidrata kao rezervnih makromolekula uz smanjenje udjela proteina. Posljednjeg dana šaržnog uzgoja u otvorenom bazenu postignuta je koncentracija biomase od 0,515 g Lˉ¹, a maksimalna produktivnost biomase od 0,8796 mg Lˉ¹ hˉ¹ postignuta je osamnaestog dana uzgoja. Šaržnim uzgojem u barbotirajućoj koloni koncentracija biomase na kraju uzgoja iznosila je 0,458 g Lˉ¹, a produktivnost sinteze biomase tada je bila 0,8297 mg Lˉ¹ hˉ¹. Kemijska flokulacija sa željezovim (III) kloridom potvrđena je kao alternativna metoda za izdvajanje stanica mikroalgi. Naposljetku, u radu je predstavljen elaborat tehničko-tehnološkog rješenja postrojenja za proizvodnju biodizela. Lipids isolated from biomass of microalgae Nannochloropsis sp. are presented as a promising feedstock for biodiesel production. Cultivation methods used in this paper were phototrophic fed-batch cultivation with substrate inflow in an open pond system on the original f/2 medium with sodium bicarbonate and phototrophic fed-batch cultivation with substrate inflow on the original f/2 medium without supplementation of carbon source in a bubble column. Changes in the content of proteins, carbohydrates and lipids were monitored in the separated algae biomass during cultivation. The composition of pigments and the profile of fatty acids in total lipids were as well monitored simultaneously. During the period of reduced phosphorus concentration it was confirmed that metabolic responses of microalgae lead to the accumulation of lipids and carbohydrates as reserve macromolecules and to a decrease in protein content. On the last day of fed-batch cultivation in open pond, biomass concentration of 0,515 g Lˉ¹ was achieved. The maximum productivity of 0,8796 mg Lˉ¹hˉ¹ was achieved eighteenth day of cultivation. Additionally, on the last day of fed-batch cultivation in bubble column, biomass concentration was 0,458 g Lˉ¹ and productivity of biomass synthesis was 0,8297 mg Lˉ¹ hˉ¹. Chemical flocculation with iron (III) chloride has been confirmed as an alternative method for microalgae cell harvesting. Lastly, technical-technological solution for a biodiesel production facility was presented in this paper.