Use Precautions of Membrane Filter

Hawach membrane filter is one of the most commonly used lab tools in many fields, such as scientific research, food testing, the chemical industry, nanotechnology, energy, and environmental protection. During the use, the following aspects need the operators to pay great attention to. Hawach provides PVDF Membrane Filters, Nylon Membrane Filters, PTFE Membrane Filters, Cellulose Acetate Membrane Filters, and other filter membranes for your choice.

  1. Handle with Clean Hands:
    • Wash your hands thoroughly before handling membrane filters to prevent contamination. Use gloves if necessary.
  2. Use Appropriate Filter Size:
    • Select a membrane filter with an appropriate pore size for the particles or microorganisms you intend to filter. The pore size should be smaller than the particles you want to retain.
  3. Inspect Filters Before Use:
    • Examine each membrane filter for defects, cracks, or irregularities before use. Damaged filters may compromise the filtration process.
  4. Pre-Wet the Membrane:
    • Pre-wet the membrane with a small volume of the solvent or liquid you will be using for filtration. This helps to remove any air bubbles and ensures a more uniform flow during filtration.
  5. Proper Installation:
    • Ensure proper installation of the membrane filter in the filtration apparatus. Follow the manufacturer’s instructions for the specific filtration setup you are using.
  6. Avoid Excessive Pressure:
    • Do not apply excessive pressure during filtration, as it may damage the membrane. Use an appropriate vacuum or pressure level as recommended by the manufacturer.
  7. Filter Compatible Solutions:
    • Check the compatibility of the membrane filter with the solvent or solution being filtered. Some solvents or chemicals may be incompatible with certain membrane materials.
  8. Use the Correct Side:
    • Membrane filters often have a designated filtration side. Ensure that you use the correct side facing the sample to achieve optimal filtration efficiency.
  9. Avoid Overloading:
    • Do not overload the membrane filter with a sample volume that exceeds its capacity. Overloading can lead to clogging and reduced filtration efficiency.
  10. Discard Single-Use Filters:
    • If using disposable membrane filters, discard them after a single use. Reusing disposable filters may lead to contamination and inaccurate results.
  11. Sterilize When Necessary:
    • Sterilize membrane filters before use if working with sensitive samples that require aseptic conditions. Autoclaving or using sterile filters is common for microbiological applications.
  12. Minimize Contact with Fingers:
    • Minimize contact with the membrane surface to prevent contamination. Use forceps or other suitable tools when handling filters.
  13. Store Properly:
    • Store membrane filters in a clean, dry environment. Protect them from exposure to light, heat, and moisture, which can affect their properties.
  14. Monitor Filtration Progress:
    • Monitor the progress of filtration and check for any signs of clogging or reduced flow. If necessary, stop the filtration and replace the membrane filter.
  15. Dispose Properly:
    • Dispose of used membrane filters in accordance with laboratory waste disposal guidelines. Some filters may contain hazardous substances that require special disposal procedures.
0.45 PES Membrane Filters Disc
0.22 Nylon Membrane Filters

Prevention From Rupture

First of all, correctly distinguish the front side (facing down) and the reverse side (facing up) of the membrane filter, otherwise, it will be easily blocked by impurities and decrease the filtration speed.

Secondly, when the temperature is low, the treated membrane filter should be immersed in the injection water that is kept at the same temperature as the liquid medicine for 5 to 10 minutes.

In this way, the tensile strength of the membrane filter will not be decreased because of the temperature difference, which could avoid the rupture or cracking phenomenon.

Also, to prevent this situation, the same size filter paper or crepe cloth could be used by putting them on the membrane filter. However, it is necessary to boil the crepe cloth with a concentration of 20g·L -1 sodium sulfonate for about 30 min, then clean it with the injection water.

Cautions in the Use of Membrane Filter

1. Measuring the foaming point: Measuring the pressure of the foaming point can reflect the pore size of the microporous membrane filter, which is closely related to the quality of the filtered liquid and an important means to ensure the quality of the microporous membrane.

2. In order to protect and prolong the service life of the filter membrane, filter paper or silk cloth of the same size can be placed on the filter membrane to prevent rupture of the filter membrane.

3. Fixed a No. 16 infusion syringe on the skin pipe head of the exhaust pipe of the filter rack and controlled by a water stop clamp, so as to avoid the rupture of the filter membrane caused by excessive exhaust pressure and speed.

4. After use, the microporous membrane is placed in the water for injection to prevent drying, but do not soak for too long. The microporous membrane that has been dehydrated and dried cannot be used.

5. Do not sterilize the filter rack together with the filter membrane, otherwise, the filter membrane will be fragile and wrinkle due to thermal expansion and cold contraction.

Performance of Nylon Membrane Filter

Hawach Nylon membrane filter is internally designed with an inert, internal polyester support web, which gives it added dimensional strength and stability to prevent cracking, curling, and breaking.

This added strength and durability are advantageous compared with traditional types during usage because it involves aggressive handling or automated equipment. As a naturally hydrophilic membrane, Hawach Nylon membrane filter does not require wetting agents that can interfere with biological processes. In addition, its high surface area and high flow rate successfully immobilize antigens, antibodies, and other proteins.

Humanization of Membrane Filter

The membrane filter provided by Hawach Scientific is customized to meet customers’ application and size requirements. The sales policy is flexible, and small order is acceptable. All customization is convenient and cost-effective because all products are manufactured on-site in Hawach facilities.
For additional information, for all customers OEM specific applications, Hawach Scientific has the product breadth and flexibility to meet customers’ needs, as well as the quality standards to help ensure customers’ success. Contact Hawach to discuss application requirements and order products.

According to the adsorption mechanism and the porosity character of the membrane and supporting layer, we can explain why the membrane filter cannot be easily blocked with clean water.

On the contrary, the wastewater with oil will lead to blocking. As for common suspended solids, particles that are larger than the membrane pore will be filtered out of the surface of the membrane.

On the other side, particles that are smaller than the membrane pore will go through, as the membrane is very thin, it cannot produce adsorption capacity to those particles. Although the supporting layer is relatively thick, as the hole is bigger than the membrane pore, it also cannot produce adsorption capacity either. In this case, only the effect of filtering out remains, so it is easy for backwashing.

When referring to the oil in the water, because of the instability, the oil drop which is larger than the membrane pore will not be always filtered out. It may split into drops that are smaller than the membrane pore and go through. Although they can go through the membrane, as they may coalesce into big oil drops and be adsorbed by the micropore in the supporting layer.

Determination of Bubble Point

Determination of the bubble point pressure is a crucial method to ensure the quality of the membrane. It can reflect the pore size of the microporous membrane filter, which is closely related to the quality of the filtered liquid. The operators could select the most suitable membrane for the samples to be tested and acquire a highly accurate testing result in the end.