semiperméable

Semiperméable refers to a type of barrier that allows certain substances to cross more readily than others, enabling selective transport between two regions. In many contexts, the preferred passage is that of a solvent such as water, while solutes are more restricted. The concept is central to processes such as osmosis and filtration.

Permeability across semiperméable membranes depends on factors including pore size, material composition, surface charge, and interactions with the membrane surface. Small, uncharged molecules may diffuse more easily, whereas charged ions and larger molecules are often hindered. In biological membranes, proteins form channels and transporters that facilitate or regulate passage. Water, for example, moves across many membranes through aquaporin channels, while other solutes move via specific transport mechanisms or are impeded by size or charge.

Types and materials include biological membranes, such as the cell membrane, and synthetic membranes used in filtration, dialysis, and separation processes. Common synthetic materials include cellulose derivatives (such as cellulose acetate), polyamides, polysulfones, and other polymeric or composite membranes. Membranes may be microporous, mesoporous, or dense, depending on their intended use and transport mechanism.

Applications span biology, medicine, and engineering. In medicine, semiperméable membranes enable dialysis and other blood purification techniques. In water treatment and desalination, osmosis and reverse osmosis rely on semiperméable barriers to separate water from dissolved solutes. In industry and research, membranes support filtration, concentration, and selective separations in food processing, pharmaceuticals, and laboratory techniques.

See also osmosis, dialysis, filtration, reverse osmosis.