Why do some microporous membranes need to be treated for hydrophilicity, and some membranes need to be treated for hydrophobicity?
1. Hydrophilic membranes and hydrophobic membranes have their own specific applications. Hydrophilic membranes are more used for sewage treatment, and hydrophobic membranes are more used for gas-water separation.
2. Why are hydrophilic membranes used in sewage treatment?
First, for hydrophobic materials such as PVDF, the membrane prepared by the immersion phase separation method is hydrophilically modified and suitable for dry membrane storage, which reduces membrane performance degradation caused by membrane regain and microbial growth, which is beneficial to transportation and storage!
The second is that in the application process, the colloid, protein, or other organic matter contained in the sewage is easy to adhere to the membrane surface to form a pollution layer, which makes the membrane water flux drop sharply, reducing the production efficiency and the use-value of the membrane. The membrane has a low filtration resistance, relatively low energy consumption, and a relatively long period of membrane fouling, which is conducive to the high output value ratio produced by the use of the membrane.
3. The hydrophobic membrane is used in membrane processes such as air filtration and membrane distillation. The better the hydrophobicity, the better the gas permeability and the improvement of production efficiency and output value ratio. All in all, different treatments for membranes, hydrophobic, or hydrophilization are all to adapt to different applications and achieve the optimal output value ratio!
Hydrophobic and Hydrophilic Forms of Membrane Filter
Hydrophobic Membrane Filter:
A hydrophobic membrane filter is characterized by its inability to absorb or allow the passage of water or aqueous solutions. Instead, it repels water, causing liquids to bead up on the surface. Hydrophobic membranes are typically made of materials like PTFE (polytetrafluoroethylene) or PVDF (polyvinylidene fluoride).
Key Characteristics of Hydrophobic Membrane Filters:
Water Repellent: They do not allow water to pass through and are used for applications where the filtration of non-aqueous solutions is required.
Air and Gas Filtration: Hydrophobic membranes are commonly used for filtering gases, as they allow air and other non-polar gases to pass through while blocking liquids.
Low Surface Tension: These membranes have a low surface tension that prevents the wetting of the membrane by water or aqueous solutions.
Venting applications in biopharmaceutical processes.
Filtration of air and gas in environmental monitoring.
Filtering non-polar solvents and oils.
Sterilization of gases in laboratories.
Hydrophilic Membrane Filter:
A hydrophilic membrane filter is designed to be wetted by water and aqueous solutions. It readily allows the passage of water through its pores. Hydrophilic membranes are typically made of materials like cellulose acetate, nylon, or PES (polyethersulfone).
Key Characteristics of Hydrophilic Membrane Filters:
Water Attraction: They attract and readily allow the passage of water and aqueous solutions.
Low Protein Binding: Hydrophilic membranes are often used in biological and pharmaceutical applications where protein binding needs to be minimized.
Biochemical and Biological Applications: These membranes are suitable for applications involving biological samples, as they allow for the passage of aqueous solutions without retaining biomolecules.
Sterilization and Filtration of Aqueous Solutions: Hydrophilic membranes are commonly used for the sterilization of culture media, filtration of biological fluids, and similar applications.
Filtration of biological samples like cell cultures and enzymes.
Sterilization of aqueous solutions and culture media.
Analysis of proteins and nucleic acids.
Diagnostic assays in medical laboratories.
In summary, the choice between a hydrophobic and hydrophilic membrane filter depends on the specific application and the nature of the substances being filtered. Hydrophobic membranes are suitable for non-aqueous solutions and gas filtration, while hydrophilic membranes are ideal for aqueous solutions and biological applications.
PVDF filter is made of polyvinylidene fluoride, which is available in two forms of the membrane: hydrophobic and hydrophilic. The protein adsorption of the hydrophilic membrane filter is much smaller than that of nitrocellulose, nylon, and PTFE membranes. It can be used in the protein solution, tissue culture medium, antibiotics, and liquid such as ethanol for de-bacterial filtration.
Removal of particle filtration can also be used for biological testing (e.g. receptor binding studies, TCA precipitation) and other applications. The hydrophobic filter membrane is suitable for gas filtration. Non-sterilizing packaging, if needed can be sterilized under high pressure, high sterilization temperature is up to 126℃; filtration with high operating temperature is up to 85℃.
Membrane filters come in two main forms based on their interaction with water: hydrophobic and hydrophilic.
Wide Chemical Compatibility of Membrane Filter
Hawach PVDF membrane filter has high flow rates, low extractability, and wide chemical compatibility. Hawach PVDF membranes filter is of less protein than nylon, PTFE membranes, and nitrocellulose.
What’s more, the Hawach membrane filter is good for clarifying the filtration of variable solutions such as strong acids, aromatics, and aggressive solvents. It can greatly increase rates of bubbles and the bubble point is higher than 0.07MPa. The range of thickness is from 90-100um and the maximum operating pressure is about 4.2 bar@23 degrees Celsius.