Semikontinuirni proces pridobivanja organskih produktov iz macesnove biomase s subkritično vodo

magistrsko delo

Blaž Košiček (Author), Mojca Škerget (Mentor), Željko Knez (Co-mentor)

Abstract

Namen magistrske naloge je bil izvesti semikontinuirni proces ekstrakcije lesne biomase s subkritično vodo (SubCW). Poleg same ekstrakcije je pri našem procesu prisotna tudi hidrotermična degradacija lesne biomase v prisotnosti subkritične vode, pri čemer nastajajo različni produkti. Ekstrahirali smo svežo macesnovo skorjo, saj študije kažejo, da macesnov les vsebuje v vodi topne substance, fenolne spojine, ki imajo visoko dodano vrednost in antioksidativne lastnosti. Preučevali smo kako različni procesni parametri – temperatura, pretok, dodatek modifikatorja (etanol) vplivajo na vrsto in količino produktov ekstrakcije in preučevali pojav hidrotermične degradacije macesnove biomase. Ekstraktom smo določili vsebnost totalnih fenolnih spojin in antioksidativno aktivnost (DPPH metoda). Spremljali smo spreminjanje kumulativne mase fenolov in kumulativne mase suhega ekstrakta s časom. Izvedli smo HPLC analizo za nekatere fenolne spojine in izračunali izkoristke ekstrakcij. Rezultati kažejo, da temperatura vpliva na količino ekstrakta. Vsebnost totalnih fenolnih spojin je bila najvišja v ekstraktih pridobljenih z vodo, ki smo ji dodali 5 vol. % etanola pri temperaturi 300 °C. Z višanjem pretoka se viša količina ekstrakta, kar pa ne moremo trditi tudi za vsebnost totalnih fenolnih spojin. Ekstrakti imajo izjemno visoko antioksidativno aktivnost. HPLC analiza kaže, da ekstrakti vsebujejo največ 5-hidroksimetilfurfurala in 2,3-dihidroksi benzojske kisline, v primeru ekstraktov pridobljenih z vodnim medijem z dodanim 10 vol. % etanola, je poleg teh dveh komponent prisotne tudi dosti 3,5-dihidroksi benzojske kisline. Modelirali smo snovni prenos totalnih fenolnih spojin iz trdne v tekočo fazo in z difuzijskimi koeficienti pokazali, da je snovni prenos totalnih fenolnih spojin v prvi stopnji mnogo hitrejši od snovnega prenosa v drugi stopnji ekstrakcijskega procesa.

Keywords

macesen;ekstrakcija;subkritična voda;hidrotermična degradacija;fenolne spojine;

Data

Language:	Slovenian
Year of publishing:	2015
Typology:	2.09 - Master's Thesis
Organization:	UM FKKT - Faculty of Chemistry and Chemical Engineering
Publisher:	[B. Košiček]
UDC:	604.4:662.6:579(043.2)
COBISS:	18470166
Views:	1927
Downloads:	148
Average score:	0 (0 votes)
Metadata:

Other data

Secondary language:	English
Secondary title:	SEMI-CONTINUOUS PROCESS FOR OBTAINING ORGANIC PRODUCTS FROM LARCH BIOMASS WITH SUBCRITICAL WATER
Secondary abstract:	The purpose of the master thesis was to establish a semi-continuous wood biomass extraction process utilized with subcritical water (SubCW) as a solvent. The extraction was accompanied by hydrothermal degradation of wood biomass leading to various products. Fresh larch bark was used for extraction since the recent studies have shown a presence of water soluble substances (phenols) with high added value and antioxidant properties. The influences of different process parameters such as temperature, flow rate and modifier addition (ethanol) on the type and quantity of extraction products and hydrothermal degradation of larch biomass were studied. The extracts were analyzed for total phenolic content and their antioxidant activity was determined. The change in cumulative weight of phenols and cumulative weight of dry extract with time was observed. The HPLC analysis of some phenolic compounds was performed and yields of extractions were calculated. The results indicate that the quantity of the extract was affected by temperature. The highest amount of total phenolic content in extracts was obtained by adding 5 volume percent of ethanol to water for extraction at 300 °C. The quantity of the extract increased with raising the flow rate of the solvent. The same cannot be said for the total phenolic content. Results indicate extremely high antioxidant activity of the extracts 5-hydroxymethylfurfural (5-HMF) and 2,3-dihydroxy benzoic acid (2,3-DHBK) were found to be the most abundant compounds according to the HPLC analysis. Beside these two components, relatively high content of 3,5-dihydroxy benzoic acid (3,5-DHBK) was also found in the extracts that were obtained with aqueous media implemented with addition of 10 volume percent of ethanol. Diffusion coefficients, which were obtained by modelling of total phenolic content mass transfer from solid to liquid phase showed, that mass transfer was much faster in the initial than latter stage of the extraction process.
Secondary keywords:	larch;extraction;subcritical water;hydrothermal degradation;phenolic compounds;
URN:	URN:SI:UM:
Type (COBISS):	Master's thesis/paper
Thesis comment:	Univ. v Mariboru, Fak. za kemijo in kemijsko tehnologijo
Pages:	XI, 84 str.
ID:	8708589