HAWACH to Discuss How to Use the Microporous Membrane

Microporous membrane is a polymer membrane material with many uniform micropores, ranging from 0.025 to 14 μm in pore size. Its filtration mechanism is mainly physical sieving. There are many types of products, commonly used acetate filter membranes, polypropylene filter membranes, polytetrafluoroethylene filter membranes, and so on. The advantages of filter membrane are high porosity, fast filtration speed, small adsorption, no retention of liquid medicine, no influence on drug content, simple equipment, convenient dismantling, etc.

The disadvantage of filter membrane is poor acid and alkali resistance and poor adaptability to certain organic solvents such as propylene glycol. The trapped particles can easily block the filter membrane and affect the filtration rate. Therefore, the membrane can be used for filtration after preliminary filtration with other filters.

Microporous membranes are indispensable consumables for microbial testing and some small-scale liquid filtration. HAWACH provides a variety of materials, microporous membranes with different diameters and pore sizes, which can be matched with different types of membrane filters or filter holders. They are widely used in testing, scientific research, the chemical industry, nanotechnology, energy and environmental protection, and many other fields.

ptfe membrane filtersFilter membranes are divided into organic membranes and water membranes. Organic membranes can pass aqueous solutions, while water membranes cannot pass organic solutions. There are different aperture specifications. Some have smooth and rough surfaces, and some have no front or back. Generally, when filtering, discard the first filtrate of 2,3ml, so as not to interfere with the detection of filter membrane impurities. After adopting the filtration step, check whether the filter membrane has adsorption of drugs.

Performance characteristics

1. Uniform pore size and high porosity;
2. The resistance is small, the flux is large, and the filtration rate is increased by more than 30%;
3. High-efficiency retention of microorganisms ≥ 107CFU/cm2 to prevent missed inspections;
4. Strong hydrophilicity, easy to absorb nutrients, and the colony grows more vigorously.


1. Microporous membrane in round shape: mixed cellulose membrane, grid membrane, nylon, polytetrafluoroethylene membrane (PTFE), polytetrafluoroethylene membrane (PTFE), polyethersulfone (PES), glass fiber membrane, polyvinylidene fluoride membrane (PVDF). The pore size range is 0.10-5.0 microns and the diameter of the diaphragm is 1-300mm, which can also be customized according to customer requirements.
2. Microporous membrane in roller: width is 260-300mm polyvinylidene fluoride membrane (PVDF), nylon reinforced membrane (JN), nylon steel tape membrane (without support layer), polytetrafluoroethylene membrane (PTFE), polyethersulfone ( PES) pore size in the range of 0.10-5.0 microns.

For the diaphragm used for analysis:

Imported microporous membranes are the same on both sides, domestic membranes are smooth on one side and slightly rough on the other side, but domestic membranes have no positive or negative sides. Because microporous membranes are symmetrical membranes, both sides have the same effect. The filter membrane is produced by coating the membrane liquid on the glass plate, and the glass side is smooth.

But there are special circumstances:

As a filtration product in large-scale production, many sample filter membranes distinguish between positive and negative: if the reverse is used, the filtration capacity will be greatly reduced, but the positive and negative sides are generally marked by the manufacturer.

The microporous filter membrane for filtering the solvent has a special suction filter bottle. When the organic solvent content does not exceed 5%, use a water membrane. Otherwise, the organic membrane is used to filter the sample with a syringe. First, draw the solution with a needle and pull out the needle. Replace the filter membrane, first put 2-3 drops in the waste liquid, and then filter into the sample.

How to use the microporous membrane?

The process of using the microporous membrane:

1. Selection of microporous membrane filter. According to the solvent to be filtered, select the microporous membrane of suitable material and specification to open the package in the clean area. For example, if the solvent to be filtered is a strong acid or a strong base, hydrophilic PTFE membrane filter is used.

2. Check the selected microporous membrane. After selecting the filter membrane, carefully check the filter membrane for holes, cracks, and foreign matter on the membrane. Due to the improvement of the production process of the microporous membrane, the quality of the current microporous membrane, whether domestic or imported, is relatively good, and the above situation will not occur.

3. Immersion of the microporous membrane. Use distilled water to rinse several times before the microporous filter membrane, and soak it in water for injection for one day to make the microporous filter membrane achieve the best effect.

(1) Cleaning frequency: Before the sterilization filtration operation, take a new microporous filter and clean it once.
Put the filter membrane flat in the clean container, soak it in distilled water of about 70 degrees to make it all wet, pour out the water after a few hours (about 4 hours or more), soak it overnight in the above method, and then use an appropriate amount of warm water before use. Soak in distilled water for cleaning.
Put the cleaned filter membrane (wet) into a suitable filter to prevent leakage around it, put the filtrate into the liquid inlet, and exhaust the air at the exhaust port, and then the filter can be carried out.
(2) Cleaning tools: clean containers, tweezers.
(3) Cleaning method:

Method 1: Take a new product, rinse the surface dust particles with purified water, and rinse it once with water for injection; put the filter membrane in a container, add an appropriate amount of water for injection, immerse, and boil for 30 minutes, and store it in an airtight place for later use.

Method 2:

(1) Take a new filter membrane and soak it in water for injection at about 70°C for 1 hour.
(2) Soak it in water for injection at about 40°C for 12 to 24 hours.
(3) Rinse with fresh water for injection before use, and then put it into the flat filter. After cleaning, hang a “cleaned” status mark on the surface of the container.

The microporous membrane can only be used as a post-stage filtration, and the filtrate must be pre-filtered through a plate frame or other filter materials to prevent the filter membrane from clogging. The method used above: is only suitable for the filtration of liquid medicine or other water solvents. Also, please note the hydrophilic membrane is suitable for ph2-9 liquid, but not suitable for strong acid and alkali or organic solvents including alcohol. If you have any questions about the use of a microporous membrane, welcome to contact HAWACH freely.

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