The extraction of oil from microalgae was investigated. The study focused on the
hydrothermal liquefaction of the microalgae Microcystis aeruginosa, Cyclotella
meneghinia and Nitzschia pusilla. M. aeruginosa was collected from the
Hartebeespoort dam, while C. meneghinia and N. pusilla were cultured in the
laboratory.
The experiments were conducted in a high pressure autoclave with an inert
atmosphere. Sodium carbonate was studied as a potential catalyst. The
hydrothermal liquefaction of M. aeruginosa, C. meneghinia and N. pusilla was carried
out at various reaction temperatures and catalyst loads. For the liquefaction of M.
aeruginosa the residence times were also varied. The reaction temperatures ranged
from 260 to 340 °C, while the catalyst loads varied between 0 and 10 wt% Na2CO3.
The residence time was varied between 15 and 45 minutes.
The study showed that hydrothermal liquefaction of M. aeruginosa produced a
maximum oil yield of 15.60 wt% at 300 °C, whereas the thermochemical liquefaction
of C. meneghinia and N. pusilla produced maximum yields of 16.03 wt% and 15.33
wt%, respectively, at 340 °C. The residence time did not influence thermochemical
liquefaction of the algae, while an increase in the catalyst load reduced the oil yield.
The reaction conditions had no effect on the elemental composition or the calorific
value of the thermochemical liquefaction oil. The calorific value of the hydrothermal
liquefaction oils ranged from 28.57 to 35.90 MJ.kg
-1
.
Hydrothermal liquefaction of microalgae produced oil that can be used as substitute
for coal in simple gasification processes. The study showed that microalgal blooms,
such as the M. aeruginosa blooms of the Hartebeespoort dam, can be used for the
extraction of oil through hydrothermal liquefaction. / Thesis (M.Ing. (Chemical Engineering))--North-West University, Potchefstroom Campus, 2010.
| Identifer | oai:union.ndltd.org:netd.ac.za/oai:union.ndltd.org:nwu/oai:dspace.nwu.ac.za:10394/3979 |
| Date | January 2009 |
| Creators | Barnard, Anro |
| Publisher | North-West University |
| Source Sets | South African National ETD Portal |
| Detected Language | English |
| Type | Thesis |
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