cryoconcentration

Cryoconcentration is a physical process in which a liquid solution becomes increasingly concentrated as a portion of the solvent freezes and solutes are rejected into the remaining unfrozen liquid.

During freezing, ice forms a purer lattice and excludes most dissolved substances, causing the concentration of solutes in the unfrozen liquid to rise. As ice fraction increases, the liquid phase becomes enriched with salts, sugars, or other solutes. The extent and rate of cryoconcentration depend on temperature, cooling rate, initial composition, and the phase behavior of the system, including any eutectic points or solubility limits.

In natural environments, cryoconcentration occurs in glaciers and sea ice where brine channels and pockets become highly concentrated in salts as ice forms. In industry, freeze concentration or cryoconcentration is used to concentrate liquids such as fruit juices or sugar solutions by controlled freezing and subsequent removal of ice, which can reduce energy use compared with evaporation.

Limitations include incomplete separation when solutes alter freezing behavior or form solids within the liquid phase, and the potential for ice inclusions or fouling during processing.