In this study, with borneol fragments in the crystallized mother liquor of natural borneol used as the raw materials, supercritical carbon dioxide method is adopted for refining to get high purity borneol. The result of the experiment shows that the yield and purity are excellent with an extraction pressure of 11 MPa, an extracting temperature of 40°C, a carbon dioxide flow rate of 25 L · h - 1 and an extraction time of 20 minutes. After detected by gas chromatography, the purity of the crystallization products could reach 96%.
Borneol (d-Borneol), also known as the D-borneol, plum slices, is commonly called camphane alcohol. Its molecular formula is C10H18O which can be sublimated; it is the white translucent crystal with strong fragrance of pine and smell of camphor and menthol [
Natural Borneol exists in five chemical types of camphor fresh leaves volatile oil (Cinnamomum camphora L. Presl). The content of volatile oil in the fresh camphor leaves is about 1.2% - 1.9% [
Supercritical CO2 extraction technology is a new extraction-separation technology which is simple and good separation effect, the product has no solvent residue and is good for heat sensitive material extraction, it’s widely used in food industry, medical industry, spices industry [
Main experimental instrument: HA121-50-01 supercritical extraction device (Jiangsu Huaan Co., Ltd.); PB403-N electronic balance Mettler-Toledo Group; Clarus 500 GC Miriam (Pekin Elmer); Erlenmeyer flask.
Main experimental reagents: ethanol (Tianjin Damao Chemical Reagent Factory); carbon dioxide gas (purity: 99.9%).
Ingredients: borneol debris (including 65.17% borneol, camphor 34.83%) (Hunan Xin huang borneol factory supplied).
Weighed 32 g borneol fragments and put into the extraction vessel, then selected temperature, pressure and flow rate of CO2, keep the temperature and pressure to extract and separate, after reaching the time, borneol and camphor were respectively removed and preserved from the extraction vessel and the separation KettleⅠ and calculate the yield and detect the purity of the borneol with gas chromatography.
Clarus 500 gas chromatograph; DB-5 column (30 m × 250 μm × 0.25); raise the temperature to 80˚C and keep the temperature for 2 min, then raise the temperature to 280˚C in speed of 3˚C min; FDI testing room with temperature of 300˚C; the injection port temperature is 250˚C; injection volume is 1.0 μL. Using area normalization method to quantitative analysis to calculate the purity and yield.
Under the processing conditions of extracting temperature is 35˚C, time is 20 min, CO2 flow rate is 10 L∙h−1, observed the influence of extracting temperature to the natural borneol separation. The results were shown in
Extraction temperature was another important parameter to affect the supercritical extraction efficiency. Selected the extracting pressure of 11 MPa, the extracting time is 20 min and CO2 flow rate is 10 L∙h−1, extracting temperature was in the range of 30˚C - 55˚C. Observed the impact of extraction kettle temperature to the separation of natural borneol. The results were shown in
The extracting pressure was 11MPa, extracting kettle temperature was 40˚C and CO2 flow rate was 10 L∙h−1, the reacting time was from 5 to 30 min, the impacts of reacting time on the separation of natural borneol are examined. The results were shown in
reaction time increaing, but the range of increasing gradually slow. According to the purity of natural borneol in unit time, it can be seen that in less than 20min, with the reaction time increasing, the borneol yield increased significantly. When the reacting was 20 min, the purity of natural borneol was 95.35%, the yield was 62.39%, After 25 min, the purity of natural borneol basically had no increase, but the yield declines rapidly. So 20 min for the extraction time was considered appropriate.
The experiment was taken under the condition of an extracting pressure of 11 MPa, an extracting kettle temperature of 40˚C and an extracting time of 20 min. And the CO2 flow rate was set from 10 L∙h−1 to 35 L∙h−1. The impacts of CO2 flow rate on the separation of natural borneol were shown in
In order to further test the optimized process of Supercritical CO2 fluid refined natural borneol. according to the experiments of 2.2.1 and taken 3 parallel tests under these conditions: extracting pressure was 11 MPa, extracting temperature was 35˚C, CO2 flow rate was 10 L∙h−1 and extracting time was 20 min. The results of three experiments were shown below. The yields were respectively 62.3%, 62.91%, 63.26% and the average value was 62.85%. The purities were respectively 98.07%, 97.53%, 98.14% and the average value was 97.71%.
According to test method in 2.2.2, the results of the products were shown in
1) The appropriate process parameters to refine natural borneol by using supercritical CO2 separation method are: the pressure is 11 MPa, the temperature is 40˚C, CO2 flow rate is 25 L∙h−1, time is 20 min. The purity and yield of natural borneol were respectively 96.66% and 61.47%.
2) Using supercritical CO2 separation to refine natural borneol has these advantages: simple operation, high efficiency, good reproducibility, high security, no organic solvent residue, no chemical changed, high yield and it could recovery by-products from camphor. And it could also be used for the purification of the crude products.
This paper funded by the Hunan province key scientific research project: “The key technology research of Efficient cultivation and using on Hunan characteristics woody medicinal materials “Project number: 2016 NK2156.
He, H.C., Deng, L.Y., He, K.D. and Chen, Q.W. (2016) Research of Supercritical CO2 Fluid Refined Natural Borneol. American Journal of Plant Sciences, 7, 1794-1801. http://dx.doi.org/10.4236/ajps.2016.713167