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Extraktion av hemicellulosa från rapshalm
KTH, School of Chemical Science and Engineering (CHE).
2016 (Swedish)Independent thesis Basic level (professional degree), 10 credits / 15 HE creditsStudent thesisAlternative title
Extraction of Hemicellulose from Rapseed Straw (English)
Abstract [sv]

Raps har odlats traditionellt i stor omfattning för att utvinna vegetabiliska oljor samt i form av biobränsle. Intresset har även ökat för rapshalmen då biopolymerer kan komma till nytta för produktion av material. Målet med projektet var att undersöka vilka parametrar som är signifikanta för att erhålla av ett högt utbyte av hemicellulosan glukomannan från rapshalm. Metoden som tillämpades under projektet var hydrotermisk extraktion med avseende på parametrarna temperatur, tid och närvaro av buffertlösningen natriumvätekarbonat. Det erhållna materialet, det vill säga hemicellulosaextraktet isolerades med hjälp av frystorkning. Materialet undersöktes med en rad analysmetoder. Detta bestod av kolhydratanalys, bestämning av molekylvikter, askhalt, och funktionella grupper. Ur hemicellulosamaterialet framställdes plastfilmer genom gjutning, där de mekaniska egenskaperna undersöktes genom dragprovning. De hydrotermiska extraktionsförsöken resulterade i ett högre utbyte vid 170 oC med lägre pH-värde samt höga halter av xylos. Extraktionsförsöken som utförde vid 150 oC gav extrakt med högre halter glukomannan, arabinos och rhamnos där de även hade större molekylvikt. Detta resulterade även i bättre mekaniska egenskaper hos plastfilmerna. Inverkan av buffertlösningen var så liten att den är försumbar.

Abstract [en]

Rapeseed has traditionally been grown extensively to extract vegetable oils as well as biofuels. There is an increased interest for the rapeseed straw as the biopolymers components can be useful in the production of materials. The aim of this project was to investigate parameters that were significant for obtaining a high yield of hemicellulose glucomannan. The used method in the project was a hydrothermal extraction in terms of parameters such as temperature, time and the presence of a sodium bicarbonate buffer solution. The obtained material, hemicellulose extract, was isolated by freeze-drying. The dry hemicellulose sample was analyzed with several analytical methods such as carbohydrate analysis, size-exclusion chromatography, thermogravimetric analysis and fourier-transform IR. Plastic films were produced with the yielded hemicellulose by casting, in which the mechanical properties were investigated by tensile testing. The hydrothermal extraction experiments resulted in a higher yield at 170 °C, with lower pH and a higher amount of xylose. Extraction experiments performed at 150 °C showed higher amounts of glucomannan, arabinose and rhamnose where they also had higher molecular weight. This resulted in better mechanical properties of the plastic films. The buffer solution made a negligible impact on the extraction.

Place, publisher, year, edition, pages
2016.
Keyword [sv]
hemicellulosa, rapshalm, extraktion
National Category
Chemical Engineering
Identifiers
URN: urn:nbn:se:kth:diva-188157OAI: oai:DiVA.org:kth-188157DiVA: diva2:933777
Educational program
Bachelor of Science in Engineering - Chemical Engineering
Available from: 2016-06-07 Created: 2016-06-07 Last updated: 2016-06-07Bibliographically approved

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