Extraction of lipids from microalgae using CO2-expanded methanol and liquid CO2

Area of Science:

• Biotechnology
• Green Chemistry
• Algal Lipid Extraction

Background:

• Botryococcus braunii is a microalga with significant lipid content suitable for biodiesel production.
• Conventional lipid extraction methods often employ harsh, non-selective, and environmentally detrimental organic solvents.
• Developing sustainable and efficient extraction techniques is crucial for algal biofuel applications.

Purpose of the Study:

• To investigate the efficacy of CO2-expanded methanol (cxMeOH) and liquid carbon dioxide (lCO2) for extracting lipids from Botryococcus braunii.
• To compare the lipid yield and selectivity of these novel methods against conventional solvents.
• To assess the environmental benefits of using cxMeOH and lCO2 in terms of solvent reduction.

Main Methods:

• Lipid extraction from Botryococcus braunii using cxMeOH under pressure.
• Lipid extraction using non-polar liquid carbon dioxide (lCO2).
• Solid phase extraction to quantify extracted lipids and assess selectivity.

Main Results:

• cxMeOH demonstrated a significantly higher extraction yield (21 mg/mL) compared to neat methanol (3 mg/mL) or chloroform/methanol mixtures.
• lCO2 effectively extracted non-polar lipids, achieving up to 10% neutral lipids relative to dry algae mass.
• Both cxMeOH and lCO2 methods substantially reduced the need for volatile, flammable, or chlorinated organic solvents.

Conclusions:

• CO2-expanded methanol and liquid CO2 are effective and selective solvents for extracting lipids from Botryococcus braunii.
• These green extraction techniques offer a more sustainable alternative to traditional methods for biofuel precursor recovery.
• The improved selectivity and reduced solvent usage highlight the potential of cxMeOH and lCO2 in industrial-scale algal lipid processing.