Diatoms as Raw Material for Applications in Nanotechnology
Independent thesis Advanced level (professional degree), 20 credits / 30 HE creditsStudent thesis
Diatoms are eukaryotic unicellular microscopic algae ubiquitously found in most aquatic environments. The diatoms have a unique self-assembled micro- and nanoporous rigid cell wall, frustules, composed of amorphous silica. The remarkable hierarchical porous structure of diatom frustules makes diatoms interesting for filtration and membrane applications. In this study the two marine centric diatoms; Coscinodiscus sp and Thalassiosira eccentrica were cultured in L1 respectively Guillard’s medium(f/2) and exposed to a 12 hour light/ 12 hour dark cycle. After 3-5 weeks the diatoms were harvested and isolated. The algae were cleaned from organic matter with, for comparison reasons, either the more aggressive hydrogen peroxide or a milder washing liquid of the detergent sodium dodecyl sulfate, SDS and ethylene diamine tetraacetic acid, EDTA.
This study showed that the diatoms Coscinodiscus sp. and Thalossiosira eccentrica can be cultured in a laboratory environment fairly easy. The analysis by SEM showed that both Coscinodiscus sp. and Thalossiosira eccentrica have pores in the nano size range and a structure with potential for use as raw material for applications in the nanotechnology. The SEM analysis also revealed that the used isolation methods cleaned the frustules although an organic polymer film was identified as a matrix around the diatoms, which aggravates the determination of how effective the two different isolation methods were. The organic film, which is estimated to be a polysaccharide film, is probably a residue from the culture medium. To avoid the formation of this film further optimization of the isolation and purification methods have to be developed.
Place, publisher, year, edition, pages
2012. , 28 p.
diatoms, algae, renewable resource, isolation methods, filtration
Engineering and Technology
IdentifiersURN: urn:nbn:se:kth:diva-146201OAI: oai:DiVA.org:kth-146201DiVA: diva2:722724