| Abstract | Cilj ovog rada bio je provesti predobradu lignocelulozne sirovine (pšenične slame podrijetlom iz Hrvatskog Zagorja) u visokotlaĉnom reaktoru s H2SO4 kao katalizatorom i istražiti utjecaj različitih koncentracija kiseline i vremena zadržavanja na sastav hidrolizata. Također, željelo se optimizirati postupak predobrade slame podešavanjem vremena zadržavanja i koncentracije kiseline, kako bi se dobila tekuća faza za uzgoj mikroorganizama, s visokom koncentracijom fermentabilnih šećera i malim udjelom inhibitora fermentacije. Sastav predobrađene sirovine praćen je tijekom eksperimenata pomoću HPLC-a. Sastav izvorne sirovine uključuje 43,7 % glukana, 21,83 % ksilana i 3,37 % arabinana te 1,65 % octene kiseline, 0,85 % furana, 10,75 % lignina, od čega 0,27 % lignina netopivog u kiselini i 10,48 % lignina topivog u kiselini. Sadržaj proteina iznosi 4 %, a pepela 6 %. Najveće koncentracije fermentabilnih šećera od 13,89 % (ukupno glukan 7,34 %, ksilan 5,41 % i arabinan 1,14 %) dobivene su kod predobrade pšenične slame u uvjetima od 210 °C, 20 bara, 5 minuta zadrţavanja i 0,5 % H2SO4. U prethodno navedenim uvjetima zabilježene su i najmanje koncentracije inhibitora fermentacije (furana, mravlje kiseline, octene kiseline i levulinske kiseline). |
| Abstract (english) | The objective of this research was to conduct a pretreatment of a lignocellulose raw material (wheat straw from Hrvatsko Zagorje) for bioethanol production in a high pressure reactor with H2SO4 as a catalyst, as well as to investigate the influence of different acid concentrations and retention times on hydrolysate composition. Furthermore, the purpose of this study was to optimise the pretreatment by regulating retention time and acid concentration, as to obtain high concentration of fermentable sugars as well as minimal inhibitors content in the liquid phase. The wheat straw hydolysate composition was monitored during the experiments with the use of HPLC. Composition of untreated straw includes 43,70 % glucan, 21,83 % xylan, 3,37 % arabinan, 1,65 % acetic acid and 0,85 % furans, while the share of acid soluble lignin amounts to 0,27 % and that of acid insoluble lignin 10,48 %. Straw contains 4 % proteins and 6 % ash. Largest concentration of fermentable sugars amounting to 13, 89 % total (7,34 % glucan, 5,41 % xylan and 1,14 % arabinan) was obtained under conditions of 210 ºC and 20 bar at 5 minutes retention time with 0,5 % H2SO4. Under these conditions lowest yields of fermentation inhibitors were also detected (furans, formic acid, acetic acid and levulinic acid). |
