Supercritical CO2 fish oil extraction is a highly efficient and environmentally friendly process used to obtain high-purity EPA and DHA. By optimizing process parameters, continuous supercritical CO2 extraction allows industrial-scale production with high yield and purity. This study investigates the continuous distillation of fish oil, focusing on the effects of flow ratio, pressure, and temperature gradient on the extraction performance.
1. Materials and Equipment
Refined fish oil was obtained from commercial-grade fish oil suppliers, containing 28.5% EPA and 41.7% DHA. The supercritical CO2 continuous distillation apparatus was designed in-house. The distillation column has an inner diameter of 24mm, a height of 4.8m, six temperature zones, six feed points, and sampling ports along the column. The packing material is triangular spiral packing, allowing continuous top and bottom discharge.
2. Effect of Fish Oil and CO2 Flow Ratio on Extraction
In continuous supercritical CO2 extraction, the flow ratio of CO2 to fish oil directly affects distillation efficiency and product purity. Experiments showed that when the fish oil flow rate is 4 ml/min and the CO2 flow rate is 40 L/min (flow ratio ≈ 10), the EPA and DHA content and purity at the column bottom were optimal, without causing flooding. Adjusting the flow ratio is critical for continuous industrial operation.
3. Effect of Pressure on EPA and DHA Extraction
Pressure is a crucial factor in supercritical CO2 fish oil extraction. Increasing pressure enhances CO2 solubility, raising the total EPA and DHA content at the bottom, but may reduce overall recovery. High pressure causes CO2 to carry more light components to the top, lowering the bottom product yield. Optimizing extraction pressure is essential for continuous production efficiency.
4. Effect of Temperature Gradient on Continuous Fish Oil Distillation
The temperature gradient within the column determines selectivity and bottom product purity. Low bottom temperature can reduce EPA recovery, while increasing top temperature improves selectivity and DHA purity. Experiments indicate that an optimal temperature gradient of 42, 45, 48–90℃ balances product purity and recovery efficiency.
5. Conclusion
Continuous supercritical CO2 distillation of fish oil is feasible and supports industrial-scale production of EPA and DHA. Optimized process parameters are:
- Pressure: 12.5 MPa
- Temperature gradient: 45–90℃
- Flow ratio: fish oil 4 ml/min, CO2 40 L/min
- Feed point: second port
Under these conditions, high-purity EPA and DHA with a total content of 90.4% and a recovery of 45.7% can be obtained.
FAQ
Q1: What is supercritical CO2 fish oil extraction?
A1: It is a green, efficient method using supercritical CO2 to extract high-purity EPA and DHA from fish oil.
Q2: What is the difference between continuous and batch extraction?
A2: Continuous extraction supports industrial-scale production with higher efficiency and recovery, whereas batch extraction is more suitable for lab or small-scale studies.
Q3: How can EPA and DHA purity be maximized?
A3: Optimizing CO2 to fish oil flow ratio, extraction pressure, and temperature gradient is crucial for improving product purity.
Q4: What are the advantages of supercritical CO2 extraction?
A4: High selectivity, solvent-free, environmentally friendly, and suitable for industrial-scale high-purity EPA and DHA production.
Q5: What are the optimal process parameters?
A5: Pressure 12.5 MPa, temperature gradient 45–90℃, fish oil flow 4 ml/min, CO2 flow 40 L/min, feed point at the second port, yielding high-purity EPA and DHA efficiently.
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