Definition: A semipermeable membrane is a selective barrier that allows certain molecules or ions to pass through while restricting others. Typically, it permits the passage of solvent molecules (like water) but blocks larger solute particles.
How It Works
Semipermeable membranes function based on size, charge, or chemical affinity.
• In osmosis, water molecules move across the membrane from a region of lower solute concentration to higher solute concentration, balancing concentrations.
• In reverse osmosis, external pressure is applied to force water molecules through the membrane, leaving impurities behind.
This selective permeability is crucial in both natural biological systems and engineered filtration processes.
Applications
- Biology: Cell membranes regulate nutrient and waste transport.
- Water Purification: Reverse osmosis systems remove salts and contaminants.
- Medical Use: Dialysis membranes filter waste from blood in patients with kidney failure.
- Food Industry: Used in concentration of fruit juices and dairy processing.
- Industrial Processes: Gas separation and chemical purification.