Principle of Membrane Filters
Membrane filters operate on the principle of selective permeability, allowing certain molecules or particles to pass through while retaining others.
They use a thin, semi-permeable membrane for filtration.
Construction
Membrane: Made from materials like cellulose acetate, polyamide, or polysulfone.
Support Structure: Holds the membrane in place and provides structural integrity.
Filter Housing: Contains the membrane and provides connections for fluid flow.
Inlet/Outlet Ports: For fluid entry and exit.
Working
The fluid is forced through the membrane under pressure.
Smaller molecules and particles pass through the membrane, while larger ones are retained.
The permeate (filtered fluid) exits through the outlet port, and the retentate (retained particles) is collected or discarded.
Uses
Water purification
Pharmaceutical manufacturing
Food and beverage industry
Medical applications (e.g., dialysis)
Merits
High precision filtration with consistent pore sizes.
Can achieve very fine filtration (microfiltration, ultrafiltration, nanofiltration).
Relatively low energy consumption.
Suitable for a wide range of applications.
Demerits
Membranes can be prone to fouling.
High initial cost for certain types of membranes.
Requires pre-treatment of fluids in some cases.