What is a Membrane Filter and How Does It Work?

What is a membrane filter? How do you use a membrane filter? What is the difference between the front and back of the membrane filter? Do you know all this? If you want to know more about the membrane filter, let HAWACH introduce it below.

Taking advantage of polymer chemical materials and applying pore-forming additives on the support layer after special treatment, the microporous membranes feature easy and convenient use, which has been widely used in many industries, such as nanotechnology, chemical engineering, scientific research, and so on. It is to separate and purify by trapping particles, bacteria, and other impurities from the gas or liquid phase.

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Membranes filter types

Microporous membranes are generally made of organic membrane materials. The so-called water membranes and organic membranes refer to different liquid filtration systems. The mainly used two types of membranes filter is

1. Cellulose filter membrane (water membrane) is easily soluble in medium-polar organic solvents and is not easy to burn. Membrane filter uses in air measurement and water liquid filtration.

2. The material of nylon (polyamide) microporous membrane (organic membrane) is aliphatic nylon, which has good hydrophilicity and resistance to acid and alkali of the appropriate concentration. Nylon filter membrane is not only suitable for aqueous solutions containing acid and alkali but also suitable for organic solvents, for example, alcohols, hydrocarbons, ethers, esters, ketones, benzene and benzene homologs, dimethyl sulfoxide, etc., which is one of the microfiltration membranes with a wide range of applications.

3. Mixed Cellulose Ester (MCE) Membranes is a membrane material commonly used in laboratory and industrial filtration separation processes. Made from a mixture of cellulose acetate and nitrocellulose, it has a porous structure and can be applied to filtration needs in different fields. MCE membranes have a wide pore size range, good chemical resistance, and low protein binding properties, making them suitable for a variety of applications such as microbial separation, protein purification, and sample pretreatment. In addition, MCE membrane also has the characteristics of high mechanical strength and strong heat resistance, making it suitable for filtration tasks in various laboratory and industrial scenarios.

4. Polyethersulfone (PES) Membranes: Pore Size: 0.1 to 0.45 micrometers. Applications: Sterilization and clarification of aqueous solutions, protein concentration. Polyethersulfone (PES) membrane is a membrane material commonly used in laboratory and industrial filtration separations. Made from high-performance polymers with excellent chemical and high-temperature resistance. PES membrane has a unique microporous structure and can be used in various applications such as microbial separation, protein purification, and biotechnology. Its unique water-hydrophobic properties make it excellent in liquid handling and separation. In addition, PES membranes have excellent mechanical strength and durability, making them suitable for a variety of filtration tasks in laboratories and industrial fields.

5. Polyvinylidene Difluoride (PVDF) Membranes: Pore Size: 0.1 to 0.45 micrometers. Applications: Protein and nucleic acid purification, sterilization of solvents.

6. Polytetrafluoroethylene (PTFE) Membranes: Pore Size: Varies, from nanometers to micrometers. Applications: Chemical compatibility, air and gas filtration, aggressive solvent filtration.

7. Glass Fiber Membranes: Pore Size: Micrometers to millimeters. Applications: Prefiltration, environmental analysis, air monitoring.

How do you use a membrane filter?

Before using the microporous membrane, it should be cleaned, soaked in distilled water, and then installed in the filter. For filtering of organic solvents, it should be soaked in ethanol for cleaning. For the filtration of chromatographic samples, if it is water-based, wash and soak with distilled water, and then pre-filter it with distilled water. For the organic-based filtration, prepare pure toluene and 95% ethanol and soak it overnight, and then use pure toluene and pure ethanol to pre-filter it. Filter and use after thoroughly washing the membrane. The organic membrane will become brittle after entering the water, and the strength of the organic solvent will decrease slightly. Therefore, a 60-100 mesh nylon mesh or metal mesh should be used under the membrane to prevent the membrane from breaking.

The difference between the front and back of the microporous membrane.

Which side of the membrane is the top side?

1. Isotropic, regardless of the front and back, can trap solid particles above the rated pore size.
2. There are front and back sides, the bright side is the reverse side, and the less bright is the front side, and the inner aperture of the membrane gradually decreases from the front to the back. When in use, the front side should be facing the filtrate, that is, the filtrate flows in from the side with weak light, and the filtrate flows out from the side with strong light. To intercept the particles is equivalent to having experienced the blocking of the multi-layer filter membrane from large to small pore size, which is not easy to be clogged, and may prolong the service life.