Centrifugation

From Phyco.org

A centrifuge is a useful device for both biolipid extraction from algae and chemical separation in biodiesel.

1 Applications
2 Density
- 2.1 Biodiesel Production
- 2.2 Algae Feedstock Separation
3 Appliances
- 3.1 Westfalia

[edit] Applications

There are several steps in the biodiesel production process where centrifugation is useful. [1]

Feedstock preparation - In this case, algae must first be separated from its medium, then the oil extracted from the algae.
Separation of transesterification products - Biodiesel and glycerine must be separated, and any leftover reactants removed.
Water wash - Biodiesel can be washed of soap and glycerine using a centrifuge.
Magnasol solids removal - As an alternative to water washing, it may be possible to wash the biodiesel in Magnasol. See: Alternative Biodiesel Washing Methods

[edit] Density

Density is a comparison of mass per unit volume compared to that of water. It is an important measurement as far as centrifugation is concerned, as the centrifuge uses this property of matter to separate substances.

[edit] Biodiesel Production

Densities of substances used in biodiesel production:

Vegetable oil: 0.93 g/cm^3 [2]
Ethanol: 0.789 g/cm^3 [3]
Methanol: 0.7918 g/cm^3 [4]
Glycerine: 1.261 g/cm^3 [5]
Potassium Hydroxide (KOH): 2.0 g/cm^3 [6]

Note that the density of ethanol and methanol is similar. However, these substances are not used together to manufacture biodiesel. Only one is used. It is preferable that ethanol be used as it is more easily obtained from algae feedstocks. Also note that the densities of SVO, ethanol/methanol, glycerol, and KOH are dissimilar enough to be easily separable by a centrifuge.