What characteristics should the air sampling filter membrane have and what membrane material should
Issuing time:2023-11-27 14:09
The air contains a variety of molecules and particles, both natural and man-made. In addition to the parts that can be used, it also contains components that affect its use and even are harmful. Therefore, it must be filtered when used in some industries, especially for During the air sampling process, the analysis of molecules and particles must be as close to reality as possible, and high-precision microporous filter membranes are an indispensable filtration tool.
What are the characteristics of membrane applications for air sampling filtration?
1. The pore size of the filter membrane determines the size range of the particles it can effectively capture, which can range from sub-micron to several microns. The pore size of the membrane must be determined based on the size of air molecules and the need to sieve molecules.
2. Membrane flow rate. The filter membrane should have an appropriate flow rate to achieve effective air sampling. There should be no excessive pressure drop or blockage. On the one hand, it will deviate from the actual pressure drop. In case of damage, the result will be inaccurate and wrong. The results will not produce realistic data, a feature that is critical for high-volume air sampling.
3. Chemical compatibility. The membrane material should be chemically compatible with the target air pollutants to prevent interference or degradation of sampling particles.
4. Hydrophobicity/Hydrophilicity, Depending on the nature of the particles or contaminants in the air, the filter membrane may need to be hydrophobic or hydrophilic to ensure proper collection and retention.
5. Analytical compatibility, the filter membrane should have low background levels of trace elements or contaminants to minimize interference with subsequent analytical methods or analysis of collected particles.
6. Sterility. In some applications that require sterile air sampling, the filter membrane may need to be pre-sterilized or autoclaved to maintain the integrity of the sample.
Different industries are used. What kind of air filter membrane is suitable for the application?
For non-aqueous air pollutant sampling, industries that do not require high levels of trace elements can choose polytetrafluoroethylene (PTFE) membranes, because one of its outstanding features is hydrophobicity, which can effectively capture particulate matter and aerosol, and is resistant to water. With low affinity and strong chemical compatibility, it should be the first choice for most air sampling filter membranes.
For sampling water-based particles, such as various staining and analysis techniques used in microbial research, you can choose nitrocellulose-type membranes, which can collect microorganisms such as bacteria and fungi. They have high pore density and small pore size and can effectively filter airborne particles. Biological particles and good hydrophilicity.
In industries such as environmental monitoring, particulate matter analysis and microbial air sampling, you can choose mixed cellulose ester (MCE) pointed membranes. This type of membrane can tend to a balance between hydrophilicity and hydrophobicity and is suitable for different types of air sampling. , while the MCE membrane also has good chemical resistance and low protein binding properties, making it suitable for aqueous and non-aqueous particle collection.
For large-scale sampling in industries such as industrial hygiene and air quality testing, especially large-volume fine particle sampling, glass fiber filters are recommended because they have high particle retention capacity, are suitable for liquid and air filtration, have high flow rates and Can handle high pressure differentials, etc.
Emission monitoring, combustion analysis and industrial sampling involving harsh conditions are also common. Quartz fiber filters are recommended here. They can withstand extreme temperatures and are chemically inert. They are more suitable for sampling high temperature or corrosive gas flows.
The above analysis comes from the summary of membrane applications in most industries, but it does not represent all. The selection of air sampling membranes is a strict and professional process. Any air-using industry, especially some industries with extremely strict gas applications, must Start with gas molecular particles and select the most suitable membrane products and materials based on the usage requirements.