Selective uptake of cesium by ammonium tungstophosphate (AWP)-calcium alginate composites

The fine crystals of ammonium tungstophosphate (AWP) exchanger were immobil ized in the biopolymer consisting of calcium alginate (CaALG) gels. uptake rate of Cs+ for the AWP-CaALG composite was fairly fast and the uptake perc entage of Cs+ was above 90 % within 30 min even in the presence of 5 M HNO3 . In a wide HNO3 concentration region of 0.1 - 5 M, the distribution coeffi cient of Cs+ for the composite was about 10(4) cm(3)/g, while those for oth er nuclides, Na+, Sr2+, Co2+, Eu3+ and Am3+, were less than 10 cm(3)/g. The uptake of Cs+ followed a Langmuir-type adsorption equation, and the maximu m uptake capacity of Cs+ increased with the content of AWP immobilized in t he composite. The trace amounts of Cs-137 in the presence of 5 M NaNO3-1 M HNO3 were selectively adsorbed on the composite column. The AWP-CaALG compo site proved to be effective for the selective removal of radioactive cesium from waste solutions containing HNO3 and NaNO3.