anion exchange

The process by which an anion in a mobile (liquid) phase exchanges with another anion previously bound to a solid, positively charged phase, the latter (Cl- on anion exchanger) + OH- (in solution); combined with cation exchange, NaCl is removed from solution. Anion exchange may also be used chromatographically, to separate anions, and medicinally, to remove an anion (e.g., Cl-) from gastric contents or bile acids in the intestine.