| Process |
Membrane type and Pore size |
Membrane material |
Driving Force |
Applications |
| Microfiltration |
Symmetric microporous,
0.1 - 10 microns |
Ceramics, Metal oxides (Aluminium-, Titanium-, Zirconium-), Graphite, Polymers (Cellulose nitrate or acetate, PVDF, Polyamides, Polysulfone, PTFE,..) |
1 - 5 bar Hydrostatic pressure difference |
Sterile filtration, Clarification |
| Ultrafiltration |
Asymmetric microporous,
1 - 10 nm |
Polysulfone, Polypropylene, Nylon 6, PTFE, PVC, Acrylic Copolymer |
1 - 10 bar Hydrostatic pressure difference |
Separation of macromolecular solutions |
| Nanofiltration |
Thin-film membranes |
Cellulosic Acetate and Aromatic Polyamide |
10 - 30 bar Hydrostatic pressure difference |
Removal of hardness and desalting |
| Reverse Osmosis |
Asymmetric skin-type,
0.5 - 1.5 nm |
Polymers, Cellulosic acetate, Aromatic Polyamide |
up to 200 bar pressure difference |
Separation of salts and microsolutes from solutions |
| Pervaporation |
Asymmetric non-porous membrane |
Polyacrylonitrile, Polymers |
Vapour pressure gradient |
Separation of azeotropic mixtures |
| Vapour permeation |
Asymmetric non-porous membrane |
Polyacrylonitrile, Polymers |
Vapour pressure gradient |
Separation of azeotropic mixtures |
| Gas Separation |
Asymmetric homogeneous polymer |
Polymers & copolymers |
Hydrostatic pressure and concentration gradients |
Separation of gas mixtures |
| Electrodialysis |
Cation and anion exchange membrane |
Sulfonated cross-linked polystyrene |
Electrical potential gradient |
Desalting of ionic solutions |
