What substances can be filtered by a 0.22 micron filter membrane?

0.22 micron filter membranes are usually used in laboratories and the medical industry. They are mainly used to remove very small particles in solutions, such as bacteria. The following is a summary of the substances that the 0.22 micron filter membrane can filter:

1. Bacteria. The diameter of most bacteria ranges from about 0.2 to 2 microns. Therefore, a 0.22 micron filter membrane can effectively remove many types of bacteria. For example, E. coli is usually about 1-2 microns long and about 0.5 microns in diameter. Gold Staphylococcus aureus is about 0.8-1 micron in diameter, Bacillus subtilis is about 4-10 micron long and 0.25-1 micron wide, and Pseudomonas aeruginosa is usually 1-5 micron long and 0.5-1 micron wide. These bacteria Most of the sizes are larger than the pore size of 0.22 microns, which can be effectively retained during filtration;

2. Yeast and mold are usually larger than bacteria, so they will be intercepted by the 0.22 micron filter membrane.

3. Particles, any solid or liquid particles larger than 0.22 microns can also be removed with this type of filter membrane.

4. Spores. Bacterial spores are dormant and highly drug-resistant forms of bacteria. They are usually similar in size to or slightly smaller than the parent cell, so they can be effectively trapped by a 0.22 micron membrane.

The above are the particles that the 0.22 micron filter membrane can filter out, but it cannot remove all particles, such as:

1. Viruses. Viruses are much smaller than bacteria, usually less than 0.02-0.3 microns, and most are less than 0.1 microns in diameter, so they usually cannot be removed using standard 0.22 micron filtration membranes.

2. Mycoplasma. Mycoplasma species are among the smallest free-living organisms, with sizes ranging from approximately 0.2-0.8 µm. Some material or particles will pass through these filter membranes, depending on their actual size and shape.

3. Proteins and other macromolecules. Some proteins and other macromolecules may be slightly larger than the pore size of the membrane, but can still pass through the membrane due to their shape or flexibility.

4. Small molecules, such as salt, sugar, amino acids, monomers, etc., are much smaller than the pore size and can pass freely.

5. Pyrogens. Pyrogens are substances that cause fever after entering the human body. They include both biological substances, such as bacterial endotoxins, and non-biological substances. Bacterial endotoxins are common problems in medical applications and pharmaceutical manufacturing because they Can survive the sterilization process that kills bacteria. Although the 0.22 micron filter can effectively remove bacteria, it does not reliably remove all pyrogens, especially bacterial endotoxins, which originate from Gram-negative bacteria. Membrane endotoxins may be much smaller than 0.22 microns in monomeric form.

The above analysis of the substances filtered by the 0.22 micron microporous filter membrane, although the standard pore size of the filter membrane may be designated as "0.22 micron", the actual pore size on the filter membrane will be different due to manufacturing tolerances or the nature of the material itself, so Some smaller particles can still pass through occasionally, which is a factor that must be considered in membrane selection.