Membrane Types:
§Porous membranes used in pressure driven filtration act as a grating and use a pressure gradient that blocks any particles larger than its pores. Examples:
microfiltration and nanofiltration
§Nanofiltration and reverse osmosis membranes also rely on pressure but solvent and solutes move through the membranes by diffusion
§Electrodialysis membranes use an electrical potential and a sophisticated chemistry in order to transport the ions selectively