CO₂-triggered switchable solvent for lipid extraction from microalgal biomass.

Area of Science:

• Biotechnology
• Green Chemistry
• Algal Biomass Utilization

Background:

• Traditional lipid extraction from microalgae often involves energy-intensive processes like fractional distillation.
• Developing sustainable and efficient methods for biofuel precursor recovery is crucial for renewable energy.
• Switchable polarity solvents offer a promising alternative for tunable solvent properties in biomass processing.

Purpose of the Study:

• To propose and evaluate a novel, energy-efficient method for microalgal lipid recovery using switchable polarity solvents.
• To identify suitable secondary amines with significant polarity switching capabilities for lipid extraction and separation.
• To assess the efficiency of lipid extraction, fatty acid methyl ester (FAME) content, and solvent recovery.

Main Methods:

• Investigated switchable polarity solvents, specifically secondary amines, reacting with carbon dioxide (CO2) to alter polarity.
• Quantitatively evaluated polarity switching potential using normalized polarity energy (ETN).
• Performed lipid extraction from Chlorella vulgaris using dipropylamine (DPA) and analyzed lipid and FAME content.

Main Results:

• Dipropylamine (DPA) demonstrated the most significant polarity change (ETN from 0.452 to 0.789 kcal/mol) upon CO2 treatment.
• Achieved a lipid extraction yield of 7.51% from microalgal biomass, with a high total lipid content of 9.16%.
• Obtained a high fatty acid methyl ester (FAME) content of 95.5% and an 84.0% solvent recovery rate.

Conclusions:

• Dipropylamine (DPA) is identified as a highly effective secondary amine for switchable polarity solvent applications in microalgae.
• The proposed method enables efficient lipid extraction and subsequent separation solely through CO2 addition, enhancing energy efficiency.
• This approach offers a sustainable pathway for producing high-FAME content lipids from microalgae for biofuel production.