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What is a modified positively charged filter membrane? What are the features and applications

Issuing time:2023-08-25 11:22

Modified positively charged filter membrane refers to a filter membrane with a positive charge after chemical modification. The introduction of positive charges on the membrane surface can enhance the adsorption, repulsion or selective retention of negatively charged substances, thereby improving filtration efficiency and selectivity. This type of membrane is commonly used to filter negatively charged particles, such as certain bacteria, viruses, endotoxins, and other biological contaminants, which are attracted to the positively charged membrane surface.

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The production process for these positively charged filtration membranes, which starts with base membrane production, is a phase inversion process in which the polymer is dissolved in a solvent, the solution is cast into a membrane, and the membrane is then immersed in a coagulation bath to precipitate the polymer and form a porous structure. Then carry out the work of surface modification, introduce positive charges to chemically modify the base film, which can be done by a variety of methods, such as grafting positively charged molecules onto the surface of the film or using positively charged polymers to treat the film. to process.

Surface modification process, used to coat positively charged functional groups on the surface of the film or polymers with amino functional groups, such as amino (-NH2) or quaternary ammonium (-N+(CH3)3); polyethyleneimine (PEI), containing Amino groups (-NH2) and have strong cationic properties; chitosan, a biopolymer derived from chitin, contains amino groups; polydiallyldimethylammonium chloride (PDADMAC), which is a A cationic polymer can also be applied to the surface of the membrane to provide positive charges, and it has a wide range of uses, including water treatment and protein separation.

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What are the properties of these modified positively charged filter membranes?

1. It can enhance the retention of negatively charged particles. The main advantage of positively charged membranes is that they can effectively retain negatively charged particles, which are attracted to the surface of the membrane by electrostatic force, such as certain viruses, bacteria, and Endotoxins, proteins or organic molecules, etc.; can selectively intercept specific substances or particles, reduce fouling and biofouling, enhance antibacterial performance, and improve membrane stability and durability.

2. It has a wide range of chemical compatibility. Most positively charged membranes have a relatively wide range of chemical compatibility, so their applications are more extensive.

3. It has the characteristics of low protein binding, and some positively charged membranes show low protein binding, such as mixed cellulose ester (MCE) membrane, nylon membrane, polyvinylidene fluoride (PVDF) membrane, polyethersulfone (PES) membranes, polyacrylonitrile (PAN) membranes, etc. These membranes are widely used in protein concentration or dialysis, and other applications to reduce the loss of protein materials.

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Main fields of application of positively charged filter membranes

1. In the water treatment industry, it can be used to remove negatively charged pollutants in water, such as certain types of bacteria and viruses.

2. In the field of biopharmaceuticals, negatively charged endotoxins in biopharmaceuticals can be removed.

3. In scientific research laboratories, it can be used in research applications to help separate and purify various biological materials.

Based on the above analysis, it can be seen that, like any filtration technology, these specially modified filter membrane materials use the positively charged groups evenly distributed on the surface to adsorb negatively charged groups in the fluid through electrostatic adsorption, and they can also adsorb Particles smaller than the membrane pore size should be an important reason for its wide application. The suitability of modified positively charged filtration membranes for a particular application depends on many factors, including the characteristics of the feed stream, the desired properties of the filtrate, and the specific requirements of the filtration process. It is the most sensible approach to start from the perspective.

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