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Title:Subcritical water as a green medium for extraction and processing of natural materials
Authors:ID Ravber, Matej (Author)
ID Škerget, Mojca (Mentor) More about this mentor... New window
ID Knez, Željko (Co-mentor)
Files:.pdf DOK_Ravber_Matej_2016.pdf (3,71 MB)
MD5: ECD9CC4C4206C60504645C0B5F1B4DB4
 
Language:English
Work type:Doctoral dissertation
Typology:2.08 - Doctoral Dissertation
Organization:FKKT - Faculty of Chemistry and Chemical Engineering
Abstract:In this doctoral dissertation, the application of subcritical water as a green medium for the extraction and processing of natural materials is presented. The work is divided into three main parts. In the first part, subcritical water is proposed as a solvent for the simultaneous extraction of oil- and water-soluble phase from oily seeds. The extraction parameters, such as temperature, time and material to solvent ratio that yield the highest amounts of both phases are examined. The quality of both obtained phases is examined. The characteristics of oils obtained using subcritical water is compared to that obtained using a conventional method. The second part of this work proposes subcritical water as an efficient solvent for the isolation of bioactive phenolic compounds from wood waste, that is produced by the forestry industry. Different wood fractions are firstly extracted in batch-mode and the fraction with the highest amounts of bioactive compounds is determined. Next, semi-continuous operation is applied, where the effects of different extraction parameters are studied on the extraction yield and quality of the extract. The effect of temperature and ethanol addition to the subcritical water on the content of single phenolic compounds identified in the extracts is observed. Lastly, the cost of manufacturing of such a product is estimated by evaluating the economics of different pilot- and industrial-scale processes operating at optimal conditions determined on the laboratory scale. The last part proposes the use of subcritical water as an efficient hydrolytic medium for glycoside bonded antioxidants, specifically those found in waste agro-industrial sources. Effect of temperature, treatment time, concentration and the atmosphere used for establishing the pressure in the reactor are first studied on a model glycoside compound - rutin and the optimal combination of reaction parameters are established for the batch-mode reactor. The degradation products of the model compound are identified and the concentration/time profiles of their degradation are observed. Furthermore, the reaction kinetics explaining the degradation of the rutin standard are evaluated. In the next step, the method is implemented on a real glycosides-containing extract. The extract is hydrolyzed at conditions obtained from the first step and the free aglycone is obtained at the highest yields possible. Lastly, the process is upgraded to continuous operation and the final hydrolyzed high-purity product is recovered.
Keywords:Subcritical water, Biowaste, Extraction, Hydrolysis, Antioxidants, Hydrothermal degradation.
Place of publishing:Maribor
Publisher:[M. Ravber]
Year of publishing:2016
PID:20.500.12556/DKUM-59596 New window
UDC:66.061.3:66.094.941(043.3)
COBISS.SI-ID:19631894 New window
NUK URN:URN:SI:UM:DK:UNBEIVB5
Publication date in DKUM:16.06.2016
Views:1737
Downloads:226
Metadata:XML RDF-CHPDL DC-XML DC-RDF
Categories:KTFMB - FKKT
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Secondary language

Language:Slovenian
Title:Subkritična voda kot zelen medij za ekstrakcijo in procesiranje naravnih materialov
Abstract:Glavni namen te doktorske disertacije je bilo raziskati uporabnost subkritične vode kot zelenega medija za izolacijo in procesiranje naravnih materialov. Delo sestoji iz treh delov. Prvi del se osredotoča na uporabnost subkritične vode kot topila za sočasno ekstrakcijo v olju in vodi topne faze iz oljnih semen. V ta namen smo študirali ekstrakcijske parametre, torej vpliv temperature, časa in razmerja material/topilo na izkoristek obeh faz. Kvaliteto obeh faz smo preverili. Kvaliteto olj pridobljenih s subkritično vodo smo primerjali z oljem pridobljenim s konvencionalno metodo. Drugi del te disertacije predlaga subkritično vodo kot efektivno topilo za izolacijo bioaktivnih fenolnih spojin iz odpadnega lesa. V prvem koraku smo ekstrahirali različne frakcije odpadnega lesa, ki nastanejo pri spravljenju lesa v gozdovih z uporabo šaržnega sistema, z namenom najti najprimernejšo frakcijo za izolacijo. V drugem koraku smo uporabili semi-kontinuirni ekstrakcijski postopek, kjer smo študirali vpliv ekstrakcijskih parametrov na ekstrakcijski izkoristek in kvaliteto ekstrakta. Določili smo vpliv temperature in dodatka etanola na hidrotemično degradacijo fenolnih spojin med samo ekstrakcijo. Na koncu smo ocenili še ekonomičnost pilotnih in industrijskih procesov z različnimi kapacitetami ekstraktorja, z namenom, približno ovrednotiti cene proizvodnje takšnega produkta. Zadnji del te doktorske disertacije predlaga subkritično vodo kot efektiven reakcijski medij za hidrolizo glikozidno vezanih antioksidantov najdenih v odpadkih živilskopridelovalne industrije. Preučili smo vpliv temperature, časa, koncentracije in atmosfere uporabljene za vzpostavitev tlaka v šaržnem reaktorju na potek hidrolize ter določili optimalno kombinacijo le-teh za modelni glikozid - rutin. Določili smo produkte hidroterminčnega razpada rutina ter degradacijske profile le-te v odvisnosti od časa. Poleg tega, smo razvili tudi kinetični model, ki matematično opisuje razgradnjo rutina v kvercetin. V naslednjem koraku smo metodo implementirali na realnem ekstraktu, ki vsebuje podobne glikozide kakor modelna komponenta in skušali dobiti proste aglikone v največjem možnem izkoristku. Na koncu smo izvedli hidrolizo tudi s kontinuirnim postopkom in skušali dobiti končni hidrolizirani produkt visoke čistosti.
Keywords:Subkritična voda, Biološki odpadki, Ekstrakcija, Hidroliza, Antioksidanti, Hidrotermična degradacija.


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