Novel applications of oxygenic photosynthetic organisms : dissertationDanijel Stojković
, 2015, doctoral dissertation
Abstract: Inspired by natural microorganisms that possess a rigid cell wall to protect them in harsh conditions, individual cells of Chlamydomonas reinhardtii were artificially encapsulated with different materials and hydrogen production was enhanced.
The first attempt was to cover the cells with hydrated silicon dioxide, which is naturally formed by diatoms. The cells covered with silica were not able to produce hydrogen, but the improved TiO2-encapsualtion of Chlamydomonas reinhardtii was found to positively affect their hydrogen production under sulfur-deprived conditions. It was shown that incubation of the cells in the dark before exposure to light was necessary in order to overcome the toxic effects of the (RKK)4D8 catalytic peptide that is essential for TiO2 formation. The TiO2-encapsulated cells were able to produce H2 with about double efficiency during 5-day period compared to non-encapsulated cells. The light-to-H2 conversion efficiency of TiO2-encapsulated Chlamydomonas reinhardtii system was estimated to be more than 4 % under optimized conditions.
The encapsulation with platinum led us to discover the bioreductive properties of Chlamydomonas reinhardtii. Beside the homogeneous Pt reduction carried out by the algae, the most surprising discovery was the possibility to use algae culture for targeted heterogeneous nucleation. An important discovery was that is possible to control the nucleation mechanism and redirect predominantly homogeneous into fully heterogeneous nucleation.
Keywords: photosynthesis, H2 production, TiO2, encapsulation, Chlamydomonas reinhardtii, platinum reduction
Published in RUNG: 01.04.2015; Views: 7633; Downloads: 295
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