Abstract
The concentration of fluoride and nitrate ions in ground water increases recently because of ground water mining and heavy usage of nitrogen fertilizers in agriculture, respectively. Excessive fluoride and nitrate ions in drinking water cause a multiplicity of ill effects for human health. Thus, removal of these ions from ground water is needed for improving the quality of drinking water. The concentration of bromide ion is one of the problems in salt producing process from the sea water. In order to improve the quality of drinking water and edible salts, development of an anion-exchange membrane that has high permselectivity between anions with the same sign and the same valence is needed. Permselectivity of specific anions through anion exchange membranes depends mainly on the balance of hydoration energy of anions with hydrophilicity of the membranes and partially on the balance of the hydrated ionic size of the anions with the degree of the cross-linking of the membranes. The permselectivity can be controlled by increasing cross-linkage of the membranes, by formation of tight surface layers on the membranes, and by changing the hydrophilicity of the anion-exchange groups and membrane matrix.
