Semipermeable membrane

Semipermeable membrane is a type of biological or synthetic, polymeric membrane that will allow certain molecules or ions to pass through it by diffusion and occasionally specialized "facilitated diffusion".

Overview

The rate of passage depends on the pressure, concentration, and temperature of the molecules or solutes on either side, as well as the permeability of the membrane to each solute. Depending on the membrane and the solute, permeability may depend on solute size, solubility, properties, or chemistry. How the membrane is constructed to be selective in its permeability will determine the rate and the solute(s) that can pass through it.

Biological semipermeable membrane

In biological systems, the most common semipermeable membrane is the lipid bilayer, which allows the passage of water, oxygen, carbon dioxide, ethanol, urea, and small polar molecules. Large molecules, such as proteins, and nonpolar molecules, such as lipids, are blocked.

Synthetic semipermeable membrane

Synthetic semipermeable membranes include dialysis tubing and certain types of filtration membranes. They are commonly used in both industrial processes and in scientific laboratories.

Applications

Semipermeable membranes are essential parts of biological systems and their technologies, including the cell membrane, filtration, desalination, and dialysis.

See also

• Osmosis
• Reverse osmosis
• Dialysis (biochemistry)
• Cell membrane
• Lipid bilayer

References

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