How to Choose Membranes for Different Filtration Needs? An In-depth Interpretation of Four Core Membrane Processes

I. Introduction: Membrane Process - The "Underlying Code" of Filtration Performance

Filtration plays a crucial role in industrial production. This process can protect equipment, ensure product quality, and comply with safety regulations for green production. Consequently, a growing number of industries are paying increased attention to the role of filtration technology in production. As the key to filtration performance, filter membranes have their production processes as the decisive factor. This article will conduct an in-depth analysis of four mainstream membrane-forming processes, helping users understand the characteristics of filter membranes to select the most suitable one for different filtration requirements.

II. Process 1: Cast Membrane (Reinforced Membrane)

1. What is a Cast Membrane (Reinforced Membrane)?

2. Key Characteristics

• Chemical Stability: Resistant to acids, alkalis, and organic solvents, suitable for complex chemical environments.

• High-Temperature Resistance: Capable of withstanding high-temperature operations, with some models having a maximum operating temperature of up to 80°C.

• High Mechanical Strength: Possesses high peel strength and anti-pollution ability, suitable for high-pressure differential working conditions.

• Relatively wide pore size distribution.

• Moderate hydrophilicity.

3. Common Materials and Application Introduction

PVDF Filter Cartridges

Material Properties:

Corrosion Resistance: Excellent resistance to strong acids, strong alkalis, and organic solvents.

Temperature Adaptability: Wide temperature application range, suitable for high-temperature process requirements.

UV Stability: Suitable for outdoor installation and use.

Mechanical Strength: Good pressure resistance and long service life.

Specific Applications in the Food and Beverage Industry:

Beer: Final sterile filtration before bottling/canning

Wine: Sterile filtration to ensure product stability

Mineral Water: Final bacterial removal filtration

Soft Drinks: Carbonated beverage sterilization

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Nylon N6/N66 Filter Cartridges

Material Properties:

Mechanical Strength: Maintains structural integrity under high-pressure working conditions.

Adsorption Performance: Effectively removes ionic and molecular-level impurities from solutions.

Biocompatibility: Meets the usage requirements in the medical field.

Abrasion Resistance: Suitable for high-flow rate working conditions.

Specific Applications in the Fine Chemical Industry:

Organic Solvent Filtration with Broad Compatibility

Final Filtration for High-Purity Water Systems

Photoresist & Developer Filtration

Pre-filtration of Chemical Intermediates

Purification for Solvent Recovery Systems

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III. Process 2: Continuous Cast Membrane (Unsupported Membrane)

1. What is a Continuous Cast Membrane (Unsupported Membrane)?

The filter membrane itself can exist independently and perform filtration functions without relying on additional support structures. It has a uniform microporous structure.

2. Key Characteristics

• Chemical Stability: Resistant to acids, alkalis, and organic solvents, suitable for complex chemical environments.

• High-Temperature Resistance: Capable of withstanding high-temperature operations, with some models having a maximum operating temperature of up to 100°C.

• Low Extractables/Low Protein Binding: Can minimize the adsorption loss of target substances (such as proteins).

• Thin and Porous: Usually has a relatively thin thickness while maintaining high porosity to achieve high flow rates.

3. Common Materials and Application Introduction

PES Filter Cartridges

Material Properties:

Biocompatibility: Passes strict biosafety tests, suitable for applications in direct contact with biological fluids.

Chemical Resistance: Good resistance to a variety of chemical reagents.

Thermal Stability: Maintains stable filtration performance under high-temperature conditions.

Cleanliness Assurance: Low extractable characteristics to ensure fluid purity.

Specific Applications in the Food and Beverage Industry:

Final Sterile Filtration & Water Purification in Beer and Wine Production

Cold Sterilization & Pre-bottling Filtration in Juice Processing

Low-Temp Pasteurization & Process Water Filtration in the Dairy Industry

Final Particle Removal & Carbonated Beverage Filtration in Soft Drinks and Alcoholic Beverages

Microbial Reduction Filtration in Bottled Water Production

IV. Process 3: Stretched Membrane

1. What is a Stretched Membrane?

A porous filter membrane made through a polymer stretching process.

2. Key Characteristics

• Naturally hydrophobic.

• Chemical Stability: Resistant to acids, alkalis, and organic solvents, suitable for complex chemical environments.

• High-Temperature Resistance: Capable of withstanding high-temperature operations.

• High Mechanical Strength: Possesses high peel strength and anti-pollution ability, suitable for high-pressure differential working conditions.

3. Common Materials and Application Introduction

PTFE Filter Cartridges

Specific Applications in the Fine Chemical Industry:

Aggressive Organic Solvent Filtration

Ultrapure Chemical Particle Removal

High-Polarity Solvent Filtration

Process Stream Filtration for Catalyst Recovery

Oil, Water & Particle Removal from Process Gases

V. Process 4: Fiber Membrane

1. What is a Fiber Membrane?

2. Key Characteristics

• Pore Size Distribution: Extremely wide.

• Structure: Random structure with non-fixed membrane pores, which may change under high pressure.

• Filtration Mechanism: Mainly based on adsorption and capture.

• Core Advantage: Extremely large dirt-holding capacity.

• Applicable Scenarios: Preferred as pre-filtration or for treating high-pollution fluids, which can effectively protect downstream precision filter membranes.

VI. How to Select Filter Membranes Based on Process Characteristics?

• Pursuing precision and efficiency → Priority is given to continuous cast membranes (PES).

• Treating corrosive solvents or gases → Priority is given to stretched membranes (PTFE).

• Needing pre-filtration with high dirt-holding capacity and long service life → Priority is given to fiber membranes.

• Routine filtration balancing cost and performance → Cast membranes (PVDF, Nylon) can be selected.

VII. Conclusion

"Matching process characteristics according to application scenarios" is the key to optimizing filtration systems and achieving cost reduction and efficiency improvement.