Chlorophyll Extraction from Microalgae: A Review on the Process Engineering Aspects

Table 3

Comparison between organic solvent extraction and SCCO₂ extraction, modified from [40].

No.	Organic solvent extraction	SCCO2 extraction
1	Solvent presence is unavoidable. The amount of solvent depends on the type of solvent used. Solvent removal requires extra unit operations and increases operational cost.	SCCO2 extraction produces solvent-free extracts.
2	Heavy metal and inorganic salt contents are also unavoidable. Their levels depend on the solvent, the method of solvent recycling, the source of the raw material, and the materials used to construct the contact parts of the machinery.	Extract is completely free of heavy metals and inorganic salts since they are not extractable by the SCCO2 even if they are present in the raw material. No heavy metals are present in the CO2 extractant or the SFE system.
3	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 may form polymers which lead to discoloration of the extract.	Due its nonpolar nature, SCCO2 will not extract any polar substance.