Keywords: essential oil, rose, water vapor, steam, extraction
The essential oils of plants are the source of the aromatic flavor of flowers, which have medical benefits and are also very expensive.
The members of our group, after discussion, thought that through the collection of information on the extraction of essential oils, we could deepen our understanding of this extraction industry. Through the personal choice, the preparation of experimental program, can improve our scientific investigation level. The unpredictable changes brought by the experiment can make us feel the hard work of successful scientific experiments. The final decision, the title is: the choice of extraction methods of essential oils and experimental investigation.
After setting up the topic of research study, we first collected information about the extraction methods of plant essential oils.
The main extraction methods are: steam distillation, chemical solvent extraction, oil separation (liposuction), freezing compression (pressing), carbon dioxide extraction. This five methods have their own characteristics: water vapor distillation: the operation of the most simple, low cost, is the most commonly used extraction methods. Chemical solvent (organic matter) extraction method: is a common extraction method for essential oils of flowers. Oleoresin Separation Method (Liposuction Method): is an expensive extraction method for flower essential oils. Freezing and compression method (pressing method): is specifically used to extract essential oils stored in the peel part of the fruit, such as citrus fruits. Carbon Dioxide Extraction: A very expensive method of extracting essential oils of near-perfect quality and very expensive.
We finally decided to use water vapor distillation and organic extraction to extract essential oils after considering the cost and difficulty of the experiment and combining the existing experimental conditions in the school.
The second step, we chose the experimental materials (plant species): in many plants (lemon grass, lavender, rosemary, geranium, tea tree, sandalwood, bergamot, eucalyptus, pine, rose, moon, mint, etc.) finally from the price of the experimental materials, the difficulty of transportation, and the prediction of experimental results, we chose rose petals as our experimental materials. After the preparation for the experiment, we started the experiment:
After discussion, we decided to follow the textbook to draw up a plan for the first experiment:
Materials and utensils:
Extract, distilled water, alcohol, phenol, NaCl, catheter, conical flasks, distillation equipment, beakers, stoppers, thin glass tubes, thermometers, iron rack, mortar, alcohol lamps, glass rods etc.
The first experiment was carried out in the morning and evening. Glass rod, etc.
Experimental steps:
After assembling the extraction equipment as shown in the figure, the rose petals were divided equally into two groups (α, γ).
Put the petals of α group into the flask, add distilled water to 1/2 place and then light the alcohol lamp.
When the water boils, the evaporated gas condenses at the condenser tube and flows out of the bullwheel into the conical flask. Collect the
extract. Stop collecting when about 20 ml of extract has been collected. Extinguish the alcohol lamp. Divide the extract into 4 groups:
a1,a2,a3,a4 in test tubes. Put a small spoonful of NaCl in group a1, phenol in group a2, NaCl with phenol in group a3
and a4 as control. The solution (yellow color) after boiling in the flask was filtered and collected,
divided into four equal groups b1,b2,b3,b4, and the experimental procedure was the same as the former counterpart. The petals of group γ were crushed into a beaker
cup, ethanol was added, and the petals were stirred in the ethanol solution with a glass rod, and left to stand until the ethanol solution was stained
rose color, and then the resulting solution was divided into 4 groups r1, ,r4, and the experimental procedure was the same as that for group a. The test tubes were covered with rubber
tubes, and then collected. All the test tubes were covered with rubber
plugs and sealed.
Theoretical basis:
After the essential oil is extracted, it will form a
turbid liquid, because the density is similar to the solution
density so it is not easy to precipitate.
The purpose of adding NaCl is to increase the density of the
solution, so that the essential oil floats in the upper layer of the
liquid and can be separated using a separatory funnel
to obtain the essential oil.
The purpose of adding phenol and alcohol is to
utilize the solubility of essential oils in organic solvents
to achieve purification.
Experimental note:
Groups a,b are cross-referenced against each other in terms of the amount of essential oil in the experimental setup, to determine which part of the setup from which the essential oil was extracted
was higher. The horizontal is to compare the liquid in the same location of the device should choose which extraction method is more ideal.
a2,b2,r4 can be used to compare the extraction of essential oils from different loads of alcohol and phenol solutions.
Experimental results: after 1 week of resting , group a was in the same state as 1 week ago, without any phenomenon. Through careful observation of the b group found b3 group bottom there is a very small amount of flocculent precipitation, the other groups for the initial yellowish, but have a light plant flavor. r1,r4 test tube floating in the upper layer of the film like an unknown substance. r1,r4 test tube, the upper layer of the film like an unknown material. There was a strong odor of alcohol when the mouth of the test tube was opened. Maybe it was diluted the aroma of essential oils, we did not smell the aromatic odor.
The results of the first experiment were quite unexpected. It almost declared the experiment a failure. We immediately set about
checking the problem,
critically analyzing the possible flaws in each step. The main 4 points are as follows:
1, The petals added to the flask were not crushed, perhaps affecting the extraction of essential oils. Resulting in a less pronounced effect.
2, the essential oil was not dissolved in distilled water, resulting in distillation of the resulting solution nearly distilled water.
3, alcohol odor is too strong, resulting in the aromatic odor of the essential oil substance can not be smelled.
4, it is impossible to extract and determine whether the "suspicious substance" is indeed rose essential oil.
We designed our own experimental program to solve the problems of the first experiment:
Materials and utensils:
Extract, alcohol, NaCl, catheter, conical flask, distillation equipment, stopper, thermometer, iron stand, water bath, mortar and pestle, etc.
Steps:
After assembling the extracting equipment as shown in the picture, the ground petals were put into the flask and added to the water bath, then the petals were put into the flask. petals into a flask, add wine exquisitely 1/2 place. Light the
alcohol lamp and control the alcohol temperature at about 78 degrees Celsius. Collect 10 ml of distillate continuously. Divide it into 2
groups: group D1, D2. group D1 was put into NaCl solution and group D2 was the control group. Separate them into conical flasks cover the mouth of the flasks with
clingfilm and tie small holes so that the alcohol can evaporate out and dust cannot easily enter.
Experimental note: In this experiment, we crushed the petals to avoid problem 1. Since the previous experiment has confirmed that essential oils do dissolve in alcohol (alcohol color changes, there is a film-like substance produced), we decided to use alcohol on the rose petals of organic solvents extraction at the same time distillation, so that the alcohol vapors to bring out the essential oils. The essential oils dissolved in alcohol thus avoiding problem 2. Since the boiling point of alcohol is 78 degrees Celsius, in order to avoid the consequences of the essential oils escaping from the bottle due to the high temperature of the liquid (higher than the boiling point of the essential oils) and not being able to be collected, we decided to control the temperature of the liquid at the boiling point of alcohol. This allows the essential oils and alcohol to be distilled "synergistically". For the final strong odor of alcohol and essential oil composition determination of the problem, we decided to use the volatile nature of alcohol to make the alcohol volatile to complete the final purification work.
Experimental results and notes: from the conical bottle of liquid can be smelled obvious plant flavor. This indicates that the distillate already contains essential oil components (a major breakthrough). After one week of resting found that D, E group no obvious difference, the liquid is transparent, colorless. There is a faint plant fragrance. As of today, the alcohol in groups D and E has not yet evaporated. No obvious signs of essential oils (flocculent precipitation) were found.
Summary of the two experiments: the first experiment we designed the experimental program as described in the book. The problems that existed in the first experiment were better solved in the second self-designed experiment. The immediate effect was the extraction of a liquid with a strong aromatic odor (compared to the first experiment). Although we have not yet been able to use our own oils, we have gained much more than 10 test tubes and 2 bottles of fragrant liquid.
In the preparation, planning and execution of the two experiments of our research study, we have gained a clear understanding of what a true inquiry experiment is. The main achievements are as follows:
The books are not omnipotent: they are only limited to describing the general steps of the experiments, but many important details related to the success of the experiments are not detailed. The discoverers of these details are often those who have experienced the failure of the experiment themselves. The lesson we have learned is that we cannot blindly trust the knowledge taught in textbooks. Practice is the only test of truth.
With the practical experience of scientific experiments: by reproducing and improving the experiments in the textbooks, we designed and executed the experimental programs on our own. And the results of the experiment were not shown to us until the last moment. It was like conducting a real scientific discovery experiment. We had never experienced such an independent inquiry-based experiment from start to finish before. We learned the hard way what it is like to be a real researcher. We experienced much more than just the pleasant aroma of essential oils ......
The results of the successful experiments were not easy to come by: the design, implementation and analysis of the two experiments, and the group members all invested a lot of time and energy. But the results of the experiment were not so satisfactory. At the same time in the disappointment, calm down and think about it, the world and what major scientific and technological achievements with just two experiments can be successful? The development of science is a process of continuous discovery and improvement, the tears of failure are always accompanied by the smile of success. We want to get the success of the experiment only to continue to summarize the lessons learned, and constantly improve the program, after many failures, success can only be in our favor. The spirit of perseverance in the experiment is unshakeable.
Conclusion: we reached the expected goal of understanding the essential oil extraction industry, completed two experiments, from which we gained the practical experience that can not be obtained from books; from which we experienced the discovery process of independent inquiry; from which we learned the hard-won scientific results ...... reached the course objectives, and successfully completed the first year of high school year research study topic.