Tannic acid is a natural organic compound with astringency and astringency, and it is a phenolic substance existing in tea. In the process of extracting caffeine, tea leaves need to be soaked in hot water to extract caffeine and other compounds. However, tannic acid in tea will interfere with the extraction process of caffeine, because it combines with caffeine to form a compound that is difficult to separate.
After adding quicklime, quicklime will react with tannic acid to produce calcium salt and hydrolysate, thus reducing the concentration of tannic acid in the solution. In this way, caffeine can be extracted from tea more easily and separated from impurities.
In addition, quicklime can also be used as a desiccant to absorb water and other volatile substances in the solution and improve the extraction efficiency. At the same time, quicklime can also be used as a pH regulator to adjust the pH value of the solution, making the extraction process more stable and controllable.
Matters needing attention in the experiment of extracting caffeine from tea;
1, experimental operation specification: During the experiment, correct operation methods should be used to ensure the accuracy and safety of experimental results. For example, when dissolving tea leaves, it is necessary to use a proper amount of acid and ensure that the acid is in full contact with tea leaves to promote the dissolution of caffeine. When adding quicklime, it is also necessary to control the amount and speed of addition to avoid excessive impurities and foam.
2. Temperature control: In the process of extracting caffeine, temperature is an important factor. If the temperature is too high, the decomposition of caffeine may fail; If the temperature is too low, the extraction efficiency may decrease. Therefore, the temperature should be controlled in a suitable range, generally around 80℃.
3. Safety issues: During the experiment, we should pay attention to safety issues. For example, be careful when using acid to avoid acid splashing into skin or eyes. In addition, after the experiment, the experimental instruments should be cleaned to avoid the damage of residual acids or other chemicals to the skin or the environment.