As we all know, glass fiber filter membranes are laboratory filtration consumables, which have the characteristics of a high flow rate and strong dirt-holding capacity and are mainly for deep filtration. Today, here are some ways to choose them.
How to choose a glass fiber filter membrane:
1. According to size
- Domestic basic filter membranes are divided into fast, medium, and slow.
- Divided into finer ones, which generally have corresponding pore sizes, such as fiber filter membrane, the aperture: 0.45μm, 1.0μm, 1.6μm;
- Diameter: 13mm, 25mm, 47mm, 50mm, 60mm, etc;
2. Purity of material
- The quality of the filter membrane mainly depends on the purity of the cotton fiber, and it is best not to have additives.
- Glass fiber material filter paper is 99.90% glass fiber material.
- In addition, glass fiber filter paper has the characteristics of a high flow rate, strong dirt-holding capacity, and can filter fine particles.
- And compared with other fiber materials and man-made materials, glass fiber material filter paper has higher filtration efficiency and stronger dirt-holding capacity.
- Because most of the basic glass fiber filter paper does not use any additives, it is just curled glass microfibers, so it is very pure.
- But because of this, should pre-wash to avoid not to remain in the filtrate in the microfibers, and should add a surface filter under the glass fiber.
3. According to usage
- There are many types of surface filtration membranes, which are hydrophilic and hydrophobic (there are also some hydrophilic and hydrophobic dual-purpose membranes).
- In short, hydrophilicity is more suitable for filtering aqueous solutions, but not for filtering organic solvents, acid-base solutions, and air; hydrophobicity is suitable for filtering organic solvents, acid-base solutions, and air.
- But in fact, depending on the filter material, they have different characteristics.
4. Polypropylene vs. glass fiber membrane
- If it is general ambient air sampling, not sampling under high-temperature conditions, should not recommend trying a glass fiber membrane.
- High-throughput polypropylene fiber membrane, suitable for large-flow sampling
- Good hydrophobic performance, not easy to absorb water vapor in the air, good constant weight performance after repeated heating, can save repeated heating process
- Small resistance, high capture efficiency
- High strength, basically no shedding of fibers
- Simple pre-treatment and strong operability
- And should recommend to use 1.0um polypropylene membrane, 0.3um>99.95%
Some tips about using glass fiber filter membranes:
1. What should I do if the glass fiber membrane is broken during filtration?
- The reasons for the rupture of the filter membrane: one is that the material cannot withstand the dissolution of the sample solvent
- And the other is the pressure that the ultrafilter can withstand during filtration.
- Then the corresponding solution is to choose a filter membrane that is resistant to the sample solvent and apply the appropriate pressure
- And especially when using a filter with a smaller diameter (for the pressure resistance of the filter, please refer to the corresponding COA).
2. What should I do if the flow rate is too slow to affect the efficiency when filtering the sample?
- When the flow rate is too slow, we need to determine whether the sample contains high particulate matter and whether the sample viscosity is too high.
- In this case, high-speed centrifugation can be performed to remove particulate matter
- And an appropriate solvent can be selected for dilution, or a filter with a larger diameter can be used.
3. What is the difference between glass fiber filter paper and conventional nylon and other microporous membranes?
- From the perspective of filtration mechanism, glass fiber filter paper is a deep filter, which is characterized by trapping particles on the surface and in the medium matrix at the same time.
- It has the characteristics of deep filtration, fast flow rate, and large loading capacity;
- While the thickness of microporous filtration membranes such as nylon is relatively thin, and it tends to surface filtration.