General Introduction and Use Notes of Filter Membrane

General introduction of the filter membrane

The filter membrane is mainly made of refined nitrocellulose, adding the appropriate amount of cellulose acetate, acetone, n-butanol, ethanol, etc. It has the characteristics of being non-toxic and hygienic. There are many ways to use it and can be applied to many different industries, and most of them are used together with filters or funnels. Commonly used microporous membranes are generally disc filters, such as 25mm disc microporous membranes, which can be used with syringe filters connected to syringes; 47mm disc microporous membranes, which can be used with membrane replacement filters, Buchner funnels, and pressure vessels. It can also be used with vacuum pumps and pressure pumps; there is also larger diameter microporous membranes, which also need to be used with corresponding fixtures and pressure.

What are the details to be aware of when using filter membranes?

Based on the materials, the filter membranes can be classified into PP filter membranes, PVDF filter membranes, PTFE filter membranes, Nylon, PES, and MCE types. But we should know the use notes for the filter membranes.

  1. Before using the filter membrane, it should be cleaned, soaked in distilled water, and then installed in the filter, and the filtration of organic solvents should be soaked and cleaned with ethanol.
  2. Before using the filter membrane, the pore size of the membrane must be accurately selected according to the needs, and the substance to be filtered must be larger than the pore size of the filter membrane.
  3. For occasions with high requirements, such as filtration of chromatographic samples or reagents, if it is water-based, rinse it with distilled water, and then pre-filter it with distilled water. If it is organic-based filtration, first put the product in pure toluene and more than 95% ethanol. Soak overnight respectively, then pre-filter with pure toluene and pure ethanol, and wash the membrane thoroughly before use. This product becomes significantly brittle after being put into water, and the reduction in strength of the organic solvent is less.
  4. When there are many particles and bacteria in the filtrate, it should be pre-filtered, that is, use a pre-filter medium or a large-pore filter membrane to filter first to avoid excessive blockage.
  5. Disinfection: The filter membrane has not been sterilized before leaving the factory, so it needs to be sterilized before use. There are many methods of disinfection. Generally, autoclaving is used, that is steam sterilization at 121°C for 30 minutes. During autoclaving, steam should be avoided. Punch directly on the membrane in one direction and prevent the back of the membrane from being damaged due to negative pressure caused by steam condensation. Boiling disinfection, chemical disinfection, etc. can also be used. During sterilization and filtration, use the air bubble method to test whether the seal is tight and whether the filter membrane is improperly sterilized. and damaged.
  6. When filtering liquid, make the filter membrane wet. If the filter membrane is in a dry state due to disinfection, it must be wetted with sterile water. The flow rate will be affected, due to the bad wetting. Sterilization, followed by sterilization filtration in a sterile room, should be carried out in strict accordance with sterilization procedures.
  7. The microporous filter membrane is flammable, not resistant to acid and alkali, and not resistant to solvents. It is only suitable for water solution (PH5-10) oil, air, fruit juice, wine, etc. Before use, it is necessary to know whether the filter material has an impact on the membrane.
  8. As the pressure, vacuum, and position are different, it is necessary to pay attention to prevent bacteria and particles in the outside air from being sucked into the polluted filtrate when vacuuming.