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Table 8 Comparison of supercritical-CO2 extraction with solvent extraction.

From: Integration of biology, ecology and engineering for sustainable algal-based biofuel and bioproduct biorefinery

Solvent extraction Supercritical CO2 extraction References
Procedure uses expensive/toxic organic solvents. Therefore, energy-intensive solvent removal operations are needed Procedure use non-toxic/inexpensive CO2 as a solvent. Extra unit operations are not needed Sahena et al. (2009)
Polar substances get dissolved along with the lipophilic substances from the raw material due to poor selectivity of the solvent. During solvent removal operations, these polar substances form polymers, which lead to discoloration of the extract No such possibility exists since CO2 is highly selective and no chance of polar substances forming polymers exists Sahena et al. (2009)
When non-polar organic solvents is used, only limited amount of neutral lipids can be extracted. When non-polar/polar organic solvent mixture is used, both neutral lipids and polar lipids are extracted The polarity of SC-CO2 can be varied by employing polar co-solvents Halim et al. (2012)
Requires little energy as ambient conditions are carried out Energy intensive due to heating (T > Tc) and compression (P > Pc) requirement for CO2 supercritical state Halim et al. (2012)