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Proizvodnja biogoriva iz obnovljivih sirovina privukla je pažnju znanstvenika jer može poslužiti za opskrbu energijom i alternativnim gorivima. Bioetanol je jedno od najzanimljivijih biogoriva zbog njegovog pozitivnog utjecaja na okoliš. Najčešće se proizvodi iz sirovina koje sadržavaju šećer i škrob. Međutim, razni izvori lignocelulozne biomase, kao što su poljoprivredni i šumski ostaci te zeljasti energetski usjevi, također mogu poslužiti kao sirovine za proizvodnju bioetanola, energije, topline i kemikalija s dodanom vrijednošću. Lignoceluloza je složena mješavina ugljikohidrata, koju treba učinkovito prethodno obraditi da bi se oslobodili biotransformacijski putevi u kojima enzimi proizvode fermentabilne šećere što nakon hidrolize fermentiraju u etanol. Unatoč tehničkim i ekonomskim poteškoćama, obnovljive lignocelulozne sirovine imaju nisku cijenu te ne utječu na hranu i prehrambeni lanac, čime potiču održivost. Za proizvodnju bioetanola iz obnovljivih sirovina razvijeni su različiti načini rada bioprocesora. Osim toga, intenzivno se razvijaju i alternativni postupci odvajanja i pročišćavanja bioetanola. Ovaj rad daje pregled novih trendova u proizvodnji bioetanola iz različitih obnovljivih sirovina, te postupaka njegovog odvajanja i pročišćavanja., Production of biofuels from renewable feedstocks has captured considerable scientific attention since they could be used to supply energy and alternative fuels. Bioethanol is one of the most interesting biofuels due to its positive impact on the environment. Currently, it is mostly produced from sugar- and starch-containing raw materials. However, various available types of lignocellulosic biomass such as agricultural and forestry residues, and herbaceous energy crops could serve as feedstocks for the production of bioethanol, energy, heat and value-added chemicals. Lignocellulose is a complex mixture of carbohydrates that needs an efficient pretreatment to make accessible pathways to enzymes for the production of fermentable sugars, which after hydrolysis are fermented into ethanol. Despite technical and economic difficulties, renewable lignocellulosic raw materials represent low-cost feedstocks that do not compete with the food and feed chain, thereby stimulating the sustainability. Different bioprocess operational modes were developed for bioethanol production from renewable raw materials. Furthermore, alternative bioethanol separation and purification processes have also been intensively developed. This paper deals with recent trends in the bioethanol production as a fuel from different renewable raw materials as well as with its separation and purification processes.

Cilj ovog diplomskog rada je istražiti primjenu viših alkohola (pentan-1-ola, oktan-1-ola, nonan-1-ola i oleil alkohola) kao ekstraktivnih otapala s visokim vrelištem za izdvajanje etanola iz fermentirane podloge u integriranom bioreaktorskom sustavu. Ekstrakcija etanola je istraživana u svrhu dobivanja ekološki, energetski i financijski učinkovitijeg procesa od uobičajeno primijenjene višestupanjske destilacije. Istraženo je toksično djelovanje ekstraktanta na kulturu kvasca Saccharomyces cerevisiae i ponašanje dvokomponentnih (ekstraktant–voda) odnosno trokomponentnih smjesa (ekstraktant-voda-etanol) te učinkovitost razdvajanja organske faze od podloge. Izrađeni su binodalni trokomponentni dijagrami za sustave pentan-1-ol/voda/etanol, oktan-1-ol/voda/etanol, nonan-1-ol/voda/etanol i oleil alkohol/voda/etanol. Na temelju binodalnih dijagrama izvršen je proračun potrebnih količina otapala za trostupanjski ekstrakcijski sustav i predložen je sustav tehnološke linije za izdvajanje etanola iz fermentirane podloge. The aim of this work was to investigate the application of higher alcohols characterized by high boiling points (i.e. pentan-1-ol, octan-1-ol, nonan-1-ol and oleyl alcohol) as extraction solvents for the ethanol extraction from broth, fermented in the integrated bioreactor system. The goal was the development of the ecologically, energetically and financially more efficient process than conventional multi-stage distillation. Applied extractants were tested for its toxicity on the Saccharomyces cerevisiae yeast culture. The behaviors of two-component systems (extractant-water) and three-component mixtures (extractant-water-ethanol) were investigated toward the efficiency of separation of organic phase (extract) and the water phase (rafinate). Binodal curves were constructed for systems: pentan-1-ol / water / ethanol, octan-1-ol / water / ethanol, nonan-1-ol / water / ethanol and oleyl alcohol / water / ethanol. Binodal diagrams were used for the calculations of required solvent amounts for the ethanol extraction in the three-stage extraction system. The plants for ethanol production based on extractions with higher alcohols were proposed.