SORPTIVE REMOVAL OF CESIUM-137 AND SR-90 FROM WATER BY UNCONVENTIONALSORBENTS .2. USAGE OF COAL FLY-ASH

It has been shown that coal fly ash is a good adsorbent for both radio nuclides of Cs-137 and Sr-90. Radiocesium adsorption is maximal around the neutral region whereas radiostrontium adsorption increases with p H, especially above pH 8. Cesium retention sharply drops with ionic st rength while strontium adsorption increases increases sharply and stea dily at low and moderate concentrations of the inert electrolyte, resp ectively. The suggested mechanisms of radionuclide retention by fly as h is specific adsorption of Cs+ and irreversible ion-exchange utake of Sr2+. The isotherm of adsorption is a Langmuir approximation of the B .E.T. multi-layered sorption. Acid pretreatment of fly ash, though not increasing radionuclide sorption capacity, may be useful in preventin g the leach-out of other contaminants from the sorbent into water duri ng the adsorption process.