Some studies on the fluoride adsorbancy of synthetic calcium monohydrogen phospchnte and synthetic sintered and unsintered zirconium silicate and beryllium silicate were made. Ten ppm of fluoride was passed at about 0.3 ml/ min through chromatographic tubes packed with the material under study together with diatomaceous earth, and the conceutration of the fluoride in the effluent solution determined. The materials which were sintered with glass adsorbed very slight amouris of fluoride. Calcium phosphate and unsintered beryllium silicate adsorbed about half of the fluoride from 50 ml of 10 ppm fluoride solution. Unsintered zirconium silicate adsorbed all detectable fluoride from such a solution. One gram of zirconium silicate adsorbed as much as 5 mg of fluoride from solution. Passing O.1 N sodium carbonate through the zirconium silicate columns caused adsorbed fluoride to be released; however, the extent of fiuoride recovery by this method varied unpredictably between 30 and 100%. (auth)
Read full abstract