Microfiltration is a precision filtration technology, which is driven by pressure along with reverse osmosis and ultrafiltration. The separated components have a diameter of 0.03-15μm; mainly removing particles, sub-particles, and fine-grained substances. We can use it in the first-end pretreatment of reverse osmosis and ultrapure water terminal treatment in the semiconductor industry. In the brewing of beer and other alcoholic beverages, it is used to remove microorganisms and odor impurities.
Made of refined nitrocellulose, microporous membrane filter adds acetone, cellulose acetate, ethanol, n-butanol, and so on with an appropriate amount. It is a porous membrane filter material with a relatively uniform pore size distribution, permeable micropores, and pore size with high microporosity, which is also called a water-based membrane. It is non-toxic and hygienic. From the structural analysis, it is an extremely thin membrane with a porous sponge-like structure. The commonly used microporous membrane filter’s pore size is from 0.1 to 10 microns.
Microporous membranes have very small, uniform pores, typically in the range of nanometers (nm) to micrometers (µm) in diameter. These pores determine the size of particles that can pass through the membrane.
They can be made from various materials, including polymers like polyethersulfone (PES), polyvinylidene fluoride (PVDF), cellulose acetate, nylon, and mixed cellulose ester (MCE), among others.
Hydrophilic or Hydrophobic:
Depending on the material and treatment, microporous membranes can be either hydrophilic (water-attracting) or hydrophobic (water-repelling). This property influences their wetting behavior and compatibility with different liquids.
Microporous membranes are compatible with a wide range of chemicals, making them suitable for various filtration applications.
Different kinds of the microporous membrane filter
There are many kinds of materials for microporous membranes, and their performances are different. Commonly used microporous membrane filters are as follows:
(1) Aqueous microporous membrane
Generally used for filtration of the pure water phase. When filtering mixed solvents containing organic phases, you should try to avoid using water-based membranes to prevent the membranes from being dissolved, because water-based membranes are generally made of cellulose-based materials.
Cellulose membrane materials are characterized by good hydrophilicity, good pore-forming properties, and a wide range of sources, but they have poor resistance to acids, alkalis, and organic solvents, and poor creep resistance. Water-based filtration membrane series include cellulose acetate membrane, nitrocellulose membrane, mixed ester membrane regenerated cellulose membrane, polyethersulfone, etc.
(2) Organic microporous membrane
Significantly hydrophilic, without pre-wetting, uniform pore size, and strong flexibility and adsorption can ensure effective retention capacity to meet the application requirements of fine filtration, good chemical compatibility, and can be used with most reagents, no fiber shedding fully meets the pharmaceutical industry standards. Used to filter organic solvents, beverage filtration, semiconductors, liquid medicine filtration, and so on.
Generally used in water systems and organic systems. Hybrid membrane filtration: nylon membrane, modified polyvinylidene fluoride (improved hydrophilicity), polytetrafluoroethylene membrane (improved hydrophilicity), polyvinylidene fluoride membrane (improved hydrophilicity). Aliphatic nylon has good hydrophilicity and resistance to acid and alkali of the appropriate concentration. It is not only suitable for aqueous solutions containing acid and alkali, but also suitable for organic solvents, such as alcohols, hydrocarbons, ethers, esters, ketones, and so on.
What are the applications of microporous filter membranes?
The microporous membrane filter is generally placed in a solvent filter, and the sample is filtered and prepared by vacuum pump suction. It is one of the most commonly used filtration methods for chromatographic mobile phase and batch samples before entering the HPLC. The microporous filter membrane is based on filtration The diameter of the membrane is different from 60mm, 50mm, 25mm, 13mm, etc. The commonly used pore sizes of microporous membranes are 0.2um, 0.45um, 0.8um, etc. Users can choose different diameters according to the size of the solvent filter selected. Different pore sizes can be selected according to the requirements of the mobile phase and the sample for the size of the impurity particles.