Why Do Some Microporous Filter Membranes Require Hydrophilic Treatment and Hydrophobic Treatment?

Microporous filter membranes are used in various applications, such as filtration, separation, and purification of liquids and gases. The need for hydrophilic and hydrophobic treatments on these membranes depends on the specific requirements of the application and the characteristics of the substances being filtered. Here’s why both treatments may be necessary:

Hydrophilic Treatment:

Enhanced Wetting: Some filter membranes inherently have hydrophobic properties, meaning they repel water and other polar liquids. However, in many filtration applications, it is essential that the membrane allows the liquid to wet the surface evenly, ensuring efficient and effective filtration. Hydrophilic treatment modifies the membrane to make it more wettable by water or other polar liquids.
Preventing Air Bubbles: In some cases, the presence of air bubbles in the filtration process can reduce the efficiency of the filter. A hydrophilic treatment can help prevent the formation of air bubbles by ensuring the liquid flows uniformly across the membrane surface.
Biological Compatibility: In applications involving biological samples or aqueous solutions, hydrophilic treatment is often necessary to prevent sample loss or adsorption to the membrane surface.

1. The hydrophilic membrane and the hydrophobic membrane have their respective targeted applications. The hydrophilic membrane is used for sewage treatment, and the hydrophobic membrane is used for gas-water separation.

2. Why is the hydrophilic membrane used for sewage treatment?

Firstly, for hydrophobic material such as PVDF, the membrane prepared by the impregnation phase separation method is suitable for dry membrane preservation after hydrophilic modification, which reduces the membrane performance degradation caused by membrane respiration 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 easily adheres to the surface of the membrane to form a pollution layer, which causes the membrane water production flux to drop drastically, reducing the production efficiency and the use value of the membrane, and finally due to the hydrophilicity. The filtration resistance of the membrane is small, the relative energy consumption is low, and the period in which the membrane is contaminated is relatively long, which is favorable for the high production ratio of the membrane. Hawach’s hydrophilic membranes include Nylon Membrane Filters, Hydrophilic PTFE Membrane Filters, PES Membrane Filters, Cellulose Acetate Membrane Filters, MCE Membrane Filters.

Hydrophobic Treatment:

Non-Polar Liquid Filtration: Some applications involve the filtration of non-polar liquids, such as certain organic solvents or oils. In such cases, a hydrophobic membrane is preferred because it repels polar liquids, allowing only the non-polar substances to pass through.
Air/Gas Filtration: In gas filtration applications, a hydrophobic membrane may be used to prevent the membrane from becoming wet, which could affect the filtration efficiency or block the passage of gases.
Chemical Compatibility: Some substances being filtered may react with water or aqueous solutions. A hydrophobic membrane can be better suited to handle such chemically aggressive materials.
In certain applications, it’s essential to have a combination of hydrophilic and hydrophobic regions on the membrane to optimize the filtration process. This can be achieved by selectively treating specific areas of the membrane or by using composite membranes with different surface properties.

3. The hydrophobic membrane is used for the membrane process such as air filtration and membrane distillation. The better the hydrophobicity, the better the permeability to the gas, and the higher the production efficiency and the ratio of production value. Hawach’s hydrophobic membranes include hydrophobic PTFE Membrane Filters, PVDF Membrane Filters, GF Membrane Filters, and PP Membrane Filters. You can choose the right filter for your application.

All in all, the membrane is treated differently, hydrophobic or hydrophilized in order to adapt to different applications, to achieve optimal production ratio! Overall, the choice of hydrophilic or hydrophobic treatment depends on the nature of the filtrate, the desired filtration efficiency, and the specific requirements of the application.