Koloidy

Koloidy, the Polish term for colloids, refer to heterogeneous mixtures in which a dispersed phase consists of tiny particles suspended in a continuous medium. The particles typically range from about 1 nanometer up to a couple of micrometers in size. In a colloid, the dispersed phase remains dispersed and does not form a true solution; under suitable conditions the mixture can be stable for long periods or may slowly separate.

Common types of colloids include sols (solid particles dispersed in a liquid, such as gold sol), gels (a three-dimensional solid network dispersed in liquid), emulsions (one liquid dispersed in another immiscible liquid, such as milk), foams (gas bubbles dispersed in a liquid), and aerosols (solid or liquid particles dispersed in a gas). Colloidal systems can also be solid in gas (aerosols) or gas in solid (aerogels, though the latter often involves gelation and drying steps).

Key properties of colloids include the Tyndall effect (scattering of light by dispersed particles), Brownian motion (random movement of particles due to collisions with molecules in the medium), and kinetic stability arising from electrostatic or steric repulsion between particles. Stability is often described by zeta potential and can be understood through DLVO theory, which considers electrostatic and van der Waals forces.

Historically, the concept arose in the 19th century with Thomas Graham and was developed further by later scientists such as Jean Perrin. Today, colloid science covers preparation, characterization, and applications across chemistry, biology, materials science, and industry.

Applications of koloidy span food products, pharmaceuticals, cosmetics, catalysts, ceramics, and environmental remediation, where controlled dispersion and stability of small particles are essential.