doctoral thesis
Mathematical modelling of supercritical CO2 extraction of oil from soybean seeds

Stela Jokić (2011)
Josip Juraj Strossmayer University of Osijek
FACULTY OF FOOD TECHNOLOGY
Department of Process Engineering
Sub-department of Process Design and Construction Materials
Metadata
TitleMatematičko modeliranje ekstrakcije ulja iz zrna soje superkritičnim CO2
AuthorStela Jokić
Mentor(s)Darko Velić
Mate Bilić
Abstract
Cilj rada bio je ispitati utjecaj tlaka (300–500 bar), temperature (40–60 °C), protoka CO2 (0,194–14,125 kg/h) i veličine čestica (0,238–1,059 mm), kao i utjecaj veličine (dimenzija) ekstraktora, na prinos ulja iz zrna soje sorte „Ika“ superkritičnim CO2. Na osnovi vanjskog koeficijenta prijenosa tvari tijekom superkritične ekstrakcije ulja s površine kvarcnog pijeska, konstruirana je nova Sherwood-ova korelacija. Iznesen je i detaljan prikaz matematičkih modela koji se koriste za opisivanje kinetike superkritične ekstrakcije biljnih ulja. Praćena je promjena kvalitete sojinog ulja tijekom provedbe ekstrakcije i to: ispitivanjem dobivenih frakcija na sastav masnih kiselina i tokoferola, primjenom plinske kromatografije, kao i pojedinačnih triacilglicerola, primjenom tekućinske kromatografije visoke djelotvornosti. Rezultati su pokazali da su, prema statističkoj značajnosti (ANOVA) utjecaja različitih procesnih uvjeta na ekstrakciju ulja iz zrna soje, tlak ekstrakcije, protok CO2 i veličina čestica imali značajan utjecaj na prinos ulja (p < 0,05), dok temperatura ekstrakcije nije pokazala statistički značajan utjecaj (p = 0,07) na prinos ulja. Smanjenjem veličine čestica te povećanjem tlaka i protoka CO2 povećavao se prinos ulja. Pri tlaku 300 bar, u intervalu od 40 do 60 °C, temperatura nije utjecala na prinos ulja te se može smatrati da je prijelazni tlak za sustav ulje iz zrna soje – superkritični CO2 upravo pri ispitanom tlaku, ili se nalazi u nekom uskom intervalu oko navedene vrijednosti tlaka. Svi ispitani matematički modeli (Kandiah i Spiro, Brunner, Tan i Liou, Martinez i sur., te Sovová model) bili su prikladni za opisivanje kinetike superkritične ekstrakcije. Međutim, na osnovi niskih AARD vrijednosti Sovová model je pokazao najbolja slaganja eksperimentalnih i modelom predviđenih podataka. Prijenos rezultata istraživanja iz laboratorijskog u poluindustrijsko mjerilo (scale-up), uspješno je proveden na temelju geometrijske sličnosti ekstraktora i mehanizma prijenosa tvari u procesu ekstrakcije. Važnost nove Sherwood-ove korelacije je u mogućnosti procjene vanjskog koeficijenta prijenosa tvari u slučajevima superkritične ekstrakcije ulja s površine neporoznih materijala, posebice kada je u pitanju prijenos rezultata iz laboratorijskog u industrijsko mjerilo. Odabirom relevantnih procesnih uvjeta superkritične ekstrakcije, kao i periodičnim frakcioniranjem, dobiveno je sojino ulje različitih masenih koncentracija masnih kiselina, triacilglicerola i tokoferola.
Keywordsextraction supercritical CO2 extraction mathematical modelling oil soybean oil
Parallel title (English)Mathematical modelling of supercritical CO2 extraction of oil from soybean seeds
Committee MembersRezica Sudar (committee chairperson)
GranterJosip Juraj Strossmayer University of Osijek
FACULTY OF FOOD TECHNOLOGY
Lower level organizational unitsDepartment of Process Engineering
Sub-department of Process Design and Construction Materials
PlaceOsijek
StateCroatia
Scientific field, discipline, subdisciplineBIOTECHNICAL SCIENCES
Food Technology
Engineering
UDK66
APPLIED SCIENCES. MEDICINE. TECHNOLOGY
Chemical technology. Chemical and related industries
Study programme typeuniversity
Study levelpostgraduate
Study programmeFood Engineering
Academic title abbreviationdr. sc.
Genredoctoral thesis
Language Croatian
Defense date2011-12-16
Parallel abstract (English)
The aim of this research was to determine the influence of pressure (300–500 bar), temperature (40–60 °C), CO2 flow rate (0.194–14.125 kg/h) and particle size (0.238–1.059 mm), as well as the influence of extractor size on the oil yield from soybean cultivar “Ika” by supercritical CO2. According to the external mass transfer coefficient during the supercritical extraction of soybean oil from the surface of spiked quartz sand a new Sherwood correlation was developed. A detailed review of mathematical models used to describe the kinetics of supercritical extraction of vegetable oils is also given. The quality change of soybean oil during the extraction was investigated as follows: the composition of fatty acids and tocopherols was determined in the extract fractions, using gas chromatography, as well as individual triacylglycerols, using high performance liquid chromatography. The results show that the extraction yield was statistically significantly (ANOVA) affected by applied operational extraction parameters of pressure, CO2 flow rate and particle size (p < 0.05). However, extraction temperature did not show statistically significant influence on extraction yield (p = 0.07). An increase of pressure and solvent flow rate, and decrease of particle size improved the extraction yield. At pressure of 300 bar and temperature interval from 40 to 60 °C, the temperature did not affect the oil yield. Thus, it can be considered that the above mentioned pressure (or pressure close to 300 bar) represents crossover pressure for soybean oil. All examined mathematical models (Kandiah and Spiro, Brunner, Tan and Liou, Martinez et al., and Sovová) were suitable for describing extraction kinetics. However, Sovová model showed the best accordance between experimental and model predicted data which was confirmed by very low AARD values. The extraction was successfully scaled-up to pilot plant according to the geometrical similarity of extractor and to the mass transfer mechanism involved on the extraction. The importance of the new Sherwood correlation lies in the fact that enables estimation of the external mass transfer coefficient in the case of supercritical extraction of oil from the surface of nonporous materials, particularly in scale-up of the results from the laboratory to industrial plant. By selecting the relevant process conditions of supercritical extraction, as well as by fractionation, it is possible to obtain soybean oil with different mass concentrations oil fatty acids, triacylglycerols and tocopherols.
Parallel keywords (Croatian)ekstrakcija ekstrakcija superkritičnim CO2 matematičko modeliranje ulje sojino ulje
Extent150 str.; ilust., graf. prikazi, 30 cm
Versionaccepted version
Resource typetext
Access conditionAccess restricted to students and staff of home institution
Terms of usehttp://rightsstatements.org/vocab/InC/1.0/
Noteaccepted version
URN:NBNhttps://urn.nsk.hr/urn:nbn:hr:109:366202
CommitterSanda Hasenay