Views: 185 Author: LOONG FILTRATION Publish Time: 2025-12-22 Origin: Site
When purchasing PVDF filter cartridges for industrial production, do you often feel confused when facing different pore sizes—should you choose a 0.2μm or 0.45μm membrane filter? This is crucial because the pore size directly determines filtration efficiency, flux, and cost. This article provides a systematic selection logic for users from the perspective of principles to applications.
PVDF membranes (Polyvinylidene Fluoride membranes) are hydrophobic solid-phase supports mainly used in Western blotting. They offer high mechanical strength, chemical solvent resistance, and thermal stability.
Capable of withstanding strong acids, alkalis, and organic solvents, these membranes feature excellent mechanical strength and tear resistance. Their outstanding stability enables them to adapt to diverse chemical environments and process conditions, laying the foundation for precise pore size selection.
| Pore Size Range | Filtration Stage | Main Applications | Applicable Industries |
| >0.45μm (e.g., 1.2μm, 5.0μm) | Prefiltration/Clarification | Remove large particles and suspended solids to protect downstream precision filter membranes | Chemical prefiltration, air filtration |
| 0.22μm≤ X ≤0.45μm | General particle removal/partial microbial retention | General particle removal and partial microbial barrier | Food and beverage clarification, industrial water treatment, filtration of large-molecular-weight proteins (>20,000 Da) |
| 0.1μm ≤ X ≤ 0.22μm | Microbial filtration/sterilizing grade | Retain bacteria and mycoplasma (0.1μm) | Pharmaceutical sterile processes, cell culture medium sterilization, final filtration |
| 0.001μm≤ X ≤0.1μm | Ultrafiltration | Separate proteins, viruses, and macromolecular organics | Bioproduct concentration and purification, wastewater reuse |
>>>Target Determines Precision:
What do you need to remove? Particles, bacteria, viruses, or proteins?
>>>Fluid Determines Compatibility:
What is your sample? Aqueous, organic solvent, acidic, or alkaline? PVDF's broad chemical compatibility becomes an advantage here.
>>>Balance Between Efficiency and Speed:
What are the requirements for flux and dirt-holding capacity? Generally, the larger the pore size, the higher the initial flux.
Quick Selection Table
| Your Process Goal | Recommended PVDF Pore Size | Key Considerations | Typical Industries |
| Sterilization/sterile filtration | 0.1μm or 0.22μm | Bacterial retention verification required (LRV>7) | Pharmaceutical, biotechnology |
| Particle removal from protein solutions | 0.2μm (<20kDa) or 0.45μm (>20kDa) | Select based on protein molecular weight to reduce adsorption | Biopharmaceutical, R&D |
| Solvent/chemical filtration | 0.1μm - 0.45μm (hydrophobic membrane) | Must use hydrophobic PVDF membranes; pay attention to solvent compatibility | Chemical, analytical testing (HPLC) |
| Process fluid prefiltration | 0.45μm or larger | High dirt-holding capacity to protect downstream | Food and beverage, general industry |
A1: The core depends on the medium you want to filter (liquid or gas) and the chemical properties of the medium. If the medium to be filtered is water or an aqueous solution, choose a hydrophilic PVDF membrane. If filtering organic solvents or gases, select a hydrophobic PVDF membrane.
During procurement, confirm with the supplier and request the bacterial retention challenge test report and integrity test standards (bubble point value or diffusion flow) for the specific model of filter cartridge. Also, ensure the filter membrane (as well as the housing and seals) can fully withstand the liquid to be filtered (composition, pH, temperature) and sterilization method (e.g., in-line steam, irradiation).
During actual use, operate below the maximum pressure difference recommended by the manufacturer, as excessive pressure can cause membrane structure deformation or bacterial penetration.
Establish good operating procedures. The entire filtration system (filter housing, pipelines, etc.) must be properly sterilized (e.g., in-line steam SIP) and connected in a sterile environment.
A3: Hydrophilicity vs. hydrophobicity, flux and pressure drop of the filter cartridge, filtration area of the filter cartridge, biosafety-related information such as endotoxin, maximum operating pressure difference and temperature, and the length and interface of the filter cartridge need to match the filter.
Choosing the PVDF membrane pore size is a systematic decision. Only by comprehensively considering all information can product quality and process stability be improved, and overall operating costs be reduced by extending membrane life and minimizing failures.
