The Removal of Flourides from Water by Ionic Exchange

Mottled enamel is the term originated by McKay to describe the disfigurement of teeth which Smith and others discovered was caused by the presence of fluorides in drinking water. Since then considerable time, energy and money have been spent in an effort to find an economical method of removing fluorides from drinking water. At first the use of activated carbon and activated alumina were rather promising; but more recently the use of tricalcium phosphate to remove fluorides from water has been developed (2). A patent by Adams and Holmes (1), wherein it was claimed that the sulphate ion concentration could be reduced nearly to zero, suggested that the fluoride content of water might be reduced to a permissible value by anionic exchange. Such a method of fluoride removal was investigated as a part of the research program concerning water treatment which has been in progress for many years at Iowa State College