Panagiotis Misaelides, David Fellhauer, Xavier Gaona, Marcus Altmaier, Horst Geckeis
Journal of Radioanalytical and Nuclear Chemistry (2016), doi:10.1007/s10967-016-5121-x
Abstract
The 232Th-uptake ([Th(IV)]° = 9.7 × 10−5 M) from carbonate solutions ([CO32]tot = 0.25 M, 9.0 < pHc < 10.8) by raw and HDTMA-modified HEU-type zeolitic-, chabazitic- and phillipsitic-tuffs was investigated. The strong uptake by the HDTMA-tuffs at pHc≈9 was assigned to the Th(CO3)56− and ThOH(CO3)45− predominance. The sorption coefficients (Rd) decreased with increasing pHc indicating carbonate competition. Enhanced Rd values for pHc > 10.5 are likely due to ThO2(am)-precipitation. The 237Np-uptake ([Np(V)]° = 2.6 × 10−5 M) from carbonate solutions ([CO32]tot = 0.25 and 3.0 × 10−4 M) by raw and HDTMA-modified HEU-type zeolitic tuff and pulverized pure heulandite crystals was studied under Ar-atmosphere at 6 < pHc < 11. The Rd values for both elements indicated the modified tuffs potential to remove tetravalent- and pentavalent actinides from environmental matrices.
