anionivaihto

Anionivaihto, often translated as anion exchange, is a separation technique used in chemistry and water treatment. It relies on the principle of using a solid material, known as an anion exchange resin, to selectively remove negatively charged ions (anions) from a liquid solution. These resins are typically composed of porous polymer beads that have positively charged functional groups attached to their surface.

The process begins by passing the solution containing unwanted anions through a column packed with the anion exchange resin. As the solution flows, the anions in the solution are attracted to the positively charged sites on the resin. They then bind to the resin, displacing other anions that were initially attached to the resin, often chloride ions. This exchange process effectively removes the target anions from the solution, purifying it.

Anion exchange is widely employed in various applications. In water purification, it is used to remove undesirable anions like nitrates, sulfates, and chromates, which can be harmful to health or impact industrial processes. It is also utilized in analytical chemistry for pre-concentration of trace anions and in the pharmaceutical industry for purification of drugs. The resin can be regenerated by flushing it with a concentrated solution of a common anion, such as sodium chloride, which displaces the bound target anions and restores the resin's capacity for further use.