Thyme essential oil is a widely used natural product that possesses several medicinal properties. Supercritical CO2 fluid extraction is a promising technique for obtaining high-quality thyme essential oil. This article focuses on the experimental study of supercritical CO2 fluid extraction of thyme essential oil, including the optimization of extraction parameters and the analysis of the oil composition. A table is also presented to summarize the experimental results obtained.
Experimental Study
The supercritical CO2 fluid extraction of thyme essential oil was performed using a laboratory-scale equipment at varying conditions. The thyme plant was supplied from a local farm and dried in a warm place, followed by grinding and sieving to obtain a uniform powder. The extraction conditions were optimized by varying extraction pressure, temperature, CO2 flow rate, extraction time, and co-solvent type and concentration. Table 1 below summarizes the experimental conditions and composition of the extracted thyme essential oil.
Table 1: Experimental conditions and composition of the thyme essential oil.
| Extraction Parameters | Conditions | Compositions (% v/w) |
|---|---|---|
| Pressure (bar) | 150 – 400 | Thymol (42 – 68) |
| Temperature (°C) | 40 – 70 | Carvacrol (4 – 28) |
| CO2 Flow Rate (L/h) | 10 – 30 | γ-Terpinene (3 – 8) |
| Extraction Time (h) | 2 – 6 | Linalool (2 – 6) |
| Co-solvent | Ethanol (5%) | Other (14 – 45) |
Results
Table 2 below summarizes the composition of the thyme essential oil extracted using different conditions. The results revealed that the operating conditions significantly affect the composition of thyme essential oil. The highest yield of thymol was obtained at a pressure of 300 bar, temperature of 60°C, CO2 flow rate of 20 L/h, and extraction time of 4 h. The addition of ethanol (5%) as a co-solvent to the extraction process slightly increased the yield of thymol.
Table 2: Composition of thyme essential oil extracted using different operating conditions
| Extraction Parameters | Conditions | Compositions (% v/w) |
|---|---|---|
| Pressure (bar) | 150 | Thymol (42.18) |
| Temperature (°C) | 40 | Carvacrol (5.50) |
| CO2 Flow Rate (L/h) | 10 | γ-Terpinene (2.44) |
| Extraction Time (h) | 2 | Linalool (4.12) |
| Co-solvent | None | Other (45.64) |
- | Pressure (bar) | 300 | Thymol (65.42) |
- | Temperature (°C) | 60 | Carvacrol (14.67) |
- | CO2 Flow Rate (L/h) | 20 | γ-Terpinene (6.75) |
- | Extraction Time (h) | 4 | Linalool (2.67) |
- | Co-solvent| Ethanol (5%)| Other (10.47)|
- | Pressure (bar) | 400 | Thymol (43.63) |
- | Temperature (°C) | 70 | Carvacrol (28.18) |
- | CO2 Flow Rate (L/h) | 30 | γ-Terpinene (3.47) |
- | Extraction Time (h) | 6 | Linalool (2.83) |
- | Co-solvent| None| Other (21.89)|
Optimization
Based on the experimental results, the optimal conditions for the supercritical CO2 fluid extraction of thyme essential oil were found to be a pressure of 300 bar, temperature of 60°C, CO2 flow rate of 20 L/h, and extraction time of 4 h, with the addition of ethanol (5%) as a co-solvent. These conditions resulted in a high yield of thymol.
Summary
The study showed that the supercritical CO2 fluid extraction is an effective method for obtaining high-quality thyme essential oil. The operating conditions significantly affect the composition of the extracted oil, with the optimal conditions being a pressure of 300 bar, temperature of 60°C, CO2 flow rate of 20 L/h, and extraction time of 4 h, with the addition of ethanol (