Keywords: steam distillation to extract rose essential oil
Plant essential oil is the source of floral fragrance, which has medical effect and is also very expensive.
After discussion, my team members think that by collecting the data of plant essential oil extraction, we can deepen our understanding of this extraction industry. Choosing and drawing up the experimental scheme in person can improve our scientific inquiry level. The unpredictable changes brought by experiments can make us feel that the success of scientific experiments is hard-won. Finally, the topic is determined as follows: the selection of extraction methods of plant essential oil and experimental exploration.
After setting the subject of research study, we first collected the relevant information about the extraction methods of plant essential oil.
The main extraction methods are: steam distillation, chemical solvent extraction, oil separation (liposuction), freeze compression (squeezing) and carbon dioxide extraction. These five methods have their own characteristics: steam distillation: the simplest operation and lower cost are the most commonly used extraction methods. Chemical solvent (organic matter) extraction method: it is a common extraction method of flower essential oil. Oil separation (liposuction): it is an expensive extraction method of flower essential oil. Freeze compression method (squeezing method): it is specially used to extract essential oil stored in peel, such as citrus fruits. Carbon dioxide extraction: This is a very expensive method. The quality of the extracted essential oil is almost perfect and the price is very expensive.
Considering the cost and difficulty of the experiment, combined with the existing experimental conditions in our school, we finally decided to choose steam distillation and organic extraction to extract essential oil.
Step 2, select experimental materials (plant varieties): among many plants (lemon citronella, lavender, rosemary, geranium, tea tree, sandalwood, bergamot, eucalyptus, pine tree, rose, rose, mint, etc. ), considering the price of experimental materials, the difficulty of transportation and the prediction of experimental results, we finally chose rose petals as our experimental materials. After the preparations for the experiment are ready, we set about the experiment:
After discussion, we decided to draw up the scheme of the first experiment according to the textbook:
Materials and appliances:
Extract, distilled water, alcohol, phenol, NaCl, catheter, conical bottle, distillation equipment, beaker, rubber stopper, thin glass tube, thermometer, hob, mortar, alcohol lamp, glass rod, etc.
Experimental steps:
After the extraction equipment is assembled as shown in the figure, the rose petals are evenly divided into two groups (α, γ).
Put the petals of group α into the flask, add distilled water to 1/2, and then light the alcohol lamp.
After the water boils, the evaporated gas will condense at the condenser tube, flow out from the trumpet tube and enter the conical flask. collect
Excerpts Collect about 20ml of extract and stop collecting. Put out the alcohol lamp. Divide the extract into 4 groups:
A 1, a2, a3, a4, put in a test tube. Put a teaspoon of NaCl into group a 1, and phenol into groups A2 and a3.
NaCl and phenol were added, and a4 was the control group. Filter and collect the boiled solution (yellow) in the flask.
Divided into four equal groups b 1, b2, b3, b4, the experimental steps are the same as the former. Crush the petals of Gamma Group and throw them into the fire.
Add ethanol into the cup, stir the petals evenly in the ethanol solution with a glass rod, and let stand until the ethanol dissolves and dyes.
After rose red, the obtained solution was divided into four groups: r 1, r4, and the experimental steps were the same as those in group A. All test tubes were covered with rubber.
Seal after plugging.
Theoretical basis:
Essential oil will be formed after extraction.
Turbid liquid, because of density and solution
The density is almost the same, and it is not easy to precipitate.
The purpose of adding NaCl is to increase
The density of the solution so that the essential oil will float on it.
Therefore, the upper liquid leaks by liquid separation.
Separating to obtain essential oil.
The purpose of adding phenol and alcohol is
Essential oil is easily soluble in organic solvents.
The properties of the product can achieve the purpose of purification.
Experiments show that:
Compare the content of essential oil in group A and group B experimental devices, and judge the part extracted from the experimental devices.
Essential oils are higher. Comparing the liquid in the same position in the horizontal direction of the device, which extraction method is more ideal?
A2, B2 and R4 can compare the extraction effects of ethanol and phenol solutions on different essential oils.
Experimental results: After standing for 1 week, the state of group A was the same as that before 1 week, and there was no phenomenon. Through careful observation of group B, it was found that there was a very small amount of flocculent precipitate at the bottom of group b3, and the other groups were light yellow at first, but all had a faint plant fragrance. An unknown substance floating in the upper layer of R 1 R4 test tube. After opening the test tube mouth, there is a strong alcohol smell. Maybe it diluted the fragrance of essential oil, and we didn't smell it.
The result of the first experiment was far beyond our expectation. This almost declared the failure of the experiment. We set about doing it at once.
Check the problem,
The possible defects in each step are carefully analyzed. There are mainly the following four points:
1, the petals added to the flask have not been ground, which may affect the extraction of essential oil. The effect is not obvious.
2. Essential oil is insoluble in distilled water, which leads to the solution obtained after distillation close to distilled water.
3. The smell of alcohol is so strong that the aromatic smell of essential oil can't be smelled.
4. It is impossible to extract and determine whether the "suspicious substance" is really rose essential oil.
Aiming at the problems in the first experiment, we designed the experiment scheme 2:
Materials and appliances:
Extract, alcohol, NaCl, catheter, conical flask, distillation equipment, rubber stopper, thermometer, hob, water bath pot, mortar, etc.
Experimental steps:
After assembling the extraction equipment as shown in the figure, put the crushed petals into a flask and add the refined wine at the position of 1/2. light
Alcohol lamp, control the alcohol temperature at about 78 degrees Celsius. Continuously collect 10ml distillate. Divide it into two parts
Group: D 1, D2. D 1 group was placed in NaCl solution, and D2 group was the control group. Respectively put into conical bottles for later use.
Plastic wrap covers the bottle mouth and is perforated. Alcohol can volatilize and dust is not easy to enter.
The experiment shows that in this experiment, we have crushed the petals to avoid the problem of 1 Since the last experiment has confirmed that the essential oil is really soluble in alcohol (the color of alcohol changes, resulting in membrane-like substances), we decided to extract rose petals with alcohol and distill at the same time, so that the alcohol vapor can bring out the essential oil. Essential oil is soluble in alcohol, which avoids the emergence of problem 2. Because the boiling point of alcohol is 78 degrees Celsius, we decided to control the liquid temperature at the boiling point of alcohol in order to avoid the consequences that the essential oil cannot be collected because the liquid temperature in the bottle is too high (higher than the boiling point of essential oil). So that essential oil and alcohol can be "cooperatively" distilled. In view of the strong smell of alcohol and the determination of essential oil components, we decided to use the volatile characteristics of alcohol to volatilize alcohol and complete the final purification work.
Experimental results and remarks: You can smell the obvious plant fragrance from the liquid in the conical flask. This shows that the distillate already contains essential oil components (a major breakthrough). After standing for a week, it was found that there was no significant difference between group D and group E, and the liquid was transparent and colorless. There is a faint plant fragrance. So far, the alcohol volatilization in Group D and Group E has not been completed. No obvious signs of essential oil (flocculent precipitation) were found.
Summary of two experiments: in the first experiment, we designed the experimental scheme according to the description in the book. The problems existed for the first time were well solved in the second self-designed experiment. The direct effect is to extract a liquid with strong aromatic smell (compared with the first experiment). Although we can't try to use the essential oil extracted by ourselves so far, our harvest is far more than 10 test tube and 2 bottles of fragrance liquid.
In the preparation, planning and implementation of two inquiry learning experiments, we have a clear understanding of the real inquiry experiment. The main gains are as follows:
I personally feel the omnipotence of books: books are only limited to describing the general steps of the experiment, but many important details related to the success of the experiment are not detailed. The discoverers of these details are often those who have personally experienced the failure of the experiment. Our experience is that we can't blindly believe what is taught in textbooks. Practice is the only criterion for testing truth.
We have practical experience in scientific experiments: through the reproduction and improvement of textbook experiments, we design and implement the experimental scheme ourselves. The experimental results were not presented to us until the last minute. It's like conducting a real scientific discovery experiment. Such an independent inquiry experiment from beginning to end has never been experienced before. From this, we can understand the hard course of being a real scientific researcher. We experience far more than the pleasant fragrance of essential oil. ...
I know that the successful experimental results are hard to come by: the team members have invested a lot of time and energy in the design, implementation and analysis of the two experiments. But the experimental results are not satisfactory. While disappointed, calm down and think about it. What are the major scientific and technological achievements in the world that only need two experiments to succeed? The development of science is a process of continuous discovery and perfection. Tears of failure are always accompanied by smiles of success. If we want to succeed in the experiment, we must constantly sum up experience and lessons and constantly improve the scheme. After many failures, success can only favor us. And the spirit of insisting on experiments is unshakable.
Conclusion: The expected purpose of understanding the essential oil extraction industry has been achieved, and two experiments have been completed, from which practical experience that cannot be obtained in books has been obtained. From this, I experienced the discovery process of independent inquiry; From it, I learned that scientific achievements are hard-won ... I achieved the purpose of the course and successfully completed the research-based learning project in Grade One.