Introduction

Hydrophilic and hydrophobic membranes are two of the most fundamental categories in filtration. Although their names sound simple, the difference between them affects everything from chemical compatibility to required pre-wetting steps and filtration efficiency. This guide explains what these terms mean, how they influence performance and how choose the right membrane for your application.

1. What Is a Hydrophilic Membrane?

Hydrophilic (“water-attracting”) membranes readily absorb and interact with water. They wet easily and allow aqueous solutions to pass through without steps.

• No pre-wetting required water-based samples
• Low protein binding depending on the material
• Ideal for biological and analytical applications

Common hydrophilic materials include PES, MCE, CA and hydrophilically treated PTFE.

2. What Is a Hydrophobic Membrane?

Hydrophobic (“water-repelling”) membranes resist water and do not allow aqueous solutions to pass unless a strong pressure is applied or a pre-wetting solvent is used.

• Excellent chemical and solvent resistance
• Ideal for air and gas filtration
• Requires pre-wetting before aqueous filtration

Typical hydrophobic materials include PTFE, PVDF (untreated) and PP.

3. How Hydrophilicity Affects Filtration Behavior

Hydrophilic membranes offer advantages for aqueous samples:

• Fast and consistent wetting
• Stable flow rate under low pressure
• Minimal risk of breakthrough or channeling

They are commonly used in sterile filtration, HPLC sample prep and protein-containing solutions.

4. How Hydrophobicity Affects Filtration Behavior

Hydrophobic membranes excel where liquid water is not the main target. p>

Allow air and gases to pass freely
• Resist clogging by aqueous samples
• Provide strong chemical and solvent compatibility

They are widely used in venting, solvent filtration, and HVAC or environmental monitoring.

5. Pre-Wetting: When and Why It’s Needed

Hydrophobic membranes require pre-wetting for water-based filtration. This step typically uses:

• Alcohols (ethanol, isopropanol)
• Low-surface-tension solvents

Once fully wetted, hydrophobic membranes behave like hydrophilic ones—at least temporarily.

6. How to Choose the Right Type

Selecting hydrophilic vs hydrophobic membranes depends on your sample:

• Aqueous solutions: hydrophilic membranes are the default choice
• Organic solvents: hydrophobic membranes provide better stability
• Air or gas filtration: hydrophobic membranes ensure unrestricted flow
• Protein-rich samples: hydrophilic, low-binding membranes improve recovery

7. Common Application Examples

• PES (hydrophilic): sterile filtration, biological buffers
• Nylon (hydrophilic): HPLC samples, organic/aqueous mixtures
• PTFE (hydrophobic): strong solvents, venting and gas filtration
• PVDF (available both types): universal lab filtration

Conclusion

Understanding the difference between hydrophilic and hydrophobic membranes allows users to choose filters more effectively. Each type offers specific advantages in wetting behavior, chemical compatibility and flow performance. Selecting the correct membrane ensures smoother workflows and more reliable results.

Purchase Suggestion

We offer a full range of hydrophilic and hydrophobic membrane filters designed for laboratory, analytical and industrial applications. Contact our technical experts to determine the best fit for your workflow.