Membrane Material and Performance Characteristics of Filter Membrane
What Are Membrane Filters Made Up Of?
Membrane filters are made up of tens of thousands of micropores. In the shape of the thin and round precut disc, membrane filters are a good tool for fast and high-efficient filtration of liquid and gas samples. From which material membrane filter can be made? We can find membrane filter material is different for your application, such as cellulose acetate, cellulose nitrate(collodion), polycarbonate, polypropylene, and polyamide (nylon). With the exception of polycarbonate filters, most other membrane filters contain a 50–85% filtering surface.
When you are selecting the membrane filters, you may find so many options to choose from in the market. How do you know which is the right one for your application? The first thing you should pick up is the right filter membrane material.
If the membrane filter is being used as a vent for a gas stream, the membrane filters are made up of Hydrophobic PTFE and Polyester (PETE) is the choice; if you want to collect air particles on the membrane surface, PTFE, Silver, PP, and glass fiber is perfect. To the liquid solution, if you are interested in particles retained on the membrane surface, Polycarbonate (PCTE) and PETE will be easy for surface retrieval and microscopy. When the filtered fluid is what you need, MCE and Nylon are perfect protein-binding capacities for sterilization, and Cellulose Acetate, PES, PP, and PVDF have good flow rates as well.
About the Commonly Used Pore Sizes and Materials of Filter Membranes
1. Pore size of membranes filter
Commonly used pore diameters are 0.22μm, 0.45μm, 0.8μm, 1.0μm
| Pore size | Applications |
| 0.22μm | 0.22μm membrane filter can remove very fine particles in samples and mobile phases; it can meet the requirements of 99.99% sterilization stipulated by GMP or Pharmacopoeia. It is suitable for the processing of solvents and samples with high requirements, such as ion-pair reagents and ultra-pure reagents for chromatography. Filter samples of water, mass spectrometry solvents, etc. It is used in color chromatography systems with fillers smaller than 3μm, 3μm, or larger. |
| 0.45μm | 0.45μm membrane filter can filter out most bacteria and microorganisms, is suitable for routine samples and mobile phase filtration, and can meet general chromatographic requirements. |
| 0.8-1.0μm | 0.8-1.0μm membrane filter can remove most insoluble particles, suitable for UV and other relatively low-demand analysis and detection of samples, higher efficiency than 0.45μm filter membrane, especially suitable for the use of insoluble excipients, suspensions, and adhesives, and the use of UV dissolution testing of oral solid preparations tested. |
| 1-5μm | Filter larger particles of impurities or pretreatment for difficult-to-handle turbid solutions. It can be filtered with a 1-5μm filter membrane and then filtered with the corresponding filter membrane. |
2. Membrane Filter materials
Common filter membranes mainly include cellulose acetate membrane filter, mixed cellulose ester microporous membrane, nylon membrane filter, polytetrafluoroethylene membrane, polyvinylidene fluoride membrane (PVDF), polyethersulfone membrane, polypropylene membrane filter(PP). Please click here to know PVDF vs PTFE
| Solvent properties | Material | Applications |
| Water system | CA | Relatively low protein adsorption, good hydrophilicity, strong chemical compatibility; pH 3-7; suitable for filtration of antibiotics, globulin, vaccine serum, and tissue culture medium, etc.; liquid sterilization, particle filtration, and other water-based samples. |
| PES | Hydrophilic membrane, large flux, both good throughput; low protein adsorption capacity, improving protein recovery application; good aging resistance, creep resistance, good chemical reagent resistance. It can be used for high-temperature liquid filtration, which is used in the filtration of biological and serum in the pharmaceutical industry, the terminal filtration of large infusion antibiotics, the terminal filtration of beverages and wine in the food industry, and the terminal filtration of ultrapure water. | |
| PVDF | The hydrophilic system has excellent anti-aging and solvent resistance can be used for a long time at -40℃~150℃ and has low protein adsorption. PVDF filter is resistant to corrosion by various strong acids, alkalis, and solvents at room temperature. It can be used for general biological samples to be filtered twice and samples with high protein recovery rates. It is soluble in strong polar solvents such as DMAC and NMP. | |
| MAC | High porosity, good interception effect; good hydrophilicity, large water flux; intolerant to organic solutions and strong acid and alkali solutions. It has the characteristics of good mechanical strength, strong thermal stability, and low adsorption, which is suitable for filtration of sterilization and particulate removal in laboratories and small production processes; sterilization and filtration of culture medium and culture liquid, etc. | |
| Organic system (filtered water system requires pre-soaking (ethanol)) | Hydrophobic PTFE | Hydrophobic PTFE can filter almost all organic solvents, has high mechanical strength, can withstand high-temperature liquids, and filters air and particulate impurities. Unless pre-soaked, the filtered aqueous solution will be difficult to advance the filtered sample due to tension obstruction. |
| Water & organic system(organic resistance, filtered water system does not need to be pre-soaked) | Nylon | The nylon membrane filter is used for the filtration of alkaline solutions and organic solvents; It is an economical choice for laboratories, not only can filter water samples, but is also compatible with most organic solvents but it cannot be used for the filtration of acid solutions, halogenated hydrocarbons, aromatic hydrocarbons, and other solutions. |
| Hydrophilic PTFE | Universal membrane, high mechanical strength, which can withstand high-temperature liquids, can withstand high-temperature liquids, filter air, and particulate impurities. Compatible with all acid and alkali solutions, the best choice for harsh laboratories. |
Performance Characteristics of HAWACH Filter Membranes
Because membrane filters are made up of tens of thousands of micropores, HAWACH filter membranes are thin membranes with high porosity which provides a high surface area for adsorption and binding. With perfect thermostability, all HAWACH membranes can be sterilized by autoclaving. Depending on the different membrane polymers, the operating temperature can be up to 180°C with minimal shrinkage.
HAWACH filter membranes are strong with the burst (longitudinal) and tensile (lateral) strength is monitored during the process of production. To produce high-quality filter membranes, we guarantee to use the high purity reagents and raw materials all the time and handle HAWACH filter membranes in a high-graded cleanroom to minimize ambient contamination.
The Procedures In Where We Use The Membrane Filters
Membrane filtration is a process that can separate the suspended particulate matter from the soluble and fluid components by the pressure forcing water or any kind of carrier fluid through a porous membrane. Having specific ratings of the pore sizes, membrane filters can keep the particles that are bigger than the size of the pores through the process of surface capture, as well as the particles which are smaller than the pore size of the membrane filter, can be kept by other types of mechanisms.
Membrane filters are useful tools for different purposes, so before you select the membrane filter for the applications, it’s important to know the types of procedures you are going to have, such as cross-flow filtration, ultrafiltration, microfiltration, nanofiltration, and reverse osmosis.
The procedure of cross-flow filtration is widely used for murky liquids such as wine, and juice, in the food industry. It can be used in dialysis too. With the filter surface’s material of stainless steel, textile fabric, or plastic, microfiltration is used in biotechnology applications, such as separating water-oil emulsions and separating colloidal hydroxides. By using low pressures and membrane filters with bigger-sized pores, nanofiltration a be used in treatments performed for drinking water such as eliminating heavy metals and softening water. The procedure of ultrafiltration is widely used only for protein separation and cold sterilization in the pharmaceutical industry, but also for wastewater cleaning and metal recovery in the field of metallurgy.
Being a pressure-driven process, reverse osmosis is used to treat process, drinking, and aquarium water. We can also find them where producing juice concentrates and treat wastewater.
Click here to know 10 Steps To Clean Membrane Filter and Membrane Filtration Principle.
