Hello Sutaphat, for your question Solvent extraction, why is filtration 2 times? Answer is The first filtration is done to separate the solid residue (like seed particles) from the initial mixture of solvent and oil after the seeds have been soaked. This helps remove larger particles and impurities that may interfere with further processing.

After the initial filtration, the mixture might still contain some smaller impurities or residual particles that were not completely removed in the first filtration. Additionally, if the solvent needs to be reused, it must be purified. The second filtration helps to ensure the solvent is free from any remaining impurities, making it suitable for further use in the extraction process.

filtration two times, the solvent extraction process can achieve a higher level of purity in both the extracted oil and the solvent, ensuring the quality of the final product and facilitating the reuse of the solvent.

Dear Sutaphat Khanwong Please do recommend my answer if helpful.

Solvent extraction processes often involve multiple filtration steps for several reasons:

1. **Removal of Solid Impurities:**

- The initial filtration step is typically performed to remove solid impurities or particulate matter that may be present in the mixture before the solvent extraction process begins. This ensures that the solvent used for extraction is relatively free of solid debris, preventing clogging of equipment and ensuring a cleaner extraction process.

2. **Separation of Extracted Solids:**

- After the solvent has been used to extract the desired components from the solid material, a second filtration step is employed to separate the extracted solids from the liquid solvent. This step helps obtain a purified solution containing the extracted compounds.

3. **Clarity and Purity:**

- Multiple filtrations contribute to the clarity and purity of the final solution. By performing successive filtration steps, finer particles and impurities are removed, leading to a cleaner and more refined product.

4. **Optimization of Process Efficiency:**

- Filtration is often used as a means of process optimization. By conducting multiple filtration steps, operators can control the quality of the solvent and the final extracted solution, improving the efficiency and effectiveness of the solvent extraction process.

5. **Prevention of Equipment Contamination:**

- Filtration helps prevent contamination of equipment and subsequent stages of the process. Solid impurities removed during the initial filtration step are prevented from entering and potentially damaging or contaminating downstream equipment.

6. **Regulatory Compliance:**

- In certain industries, regulatory standards may dictate the need for multiple filtration steps to ensure the final product meets specific purity criteria. This is particularly important in industries where product quality and purity are critical.

While the exact number of filtration steps may vary depending on the specific solvent extraction process and the nature of the materials involved, the rationale behind multiple filtrations generally revolves around improving the quality, purity, and efficiency of the overall process.

Usually, the first extraction can remove most impurities, while the second extraction further improves the purity of the target substance. By repeatedly extracting, the target substance can be effectively separated and impurities removed, resulting in a pure extract.