Separation of cesium and strontium from acidic radioactive waste simulants using a microporous tungstate/polyacrylonitrile (PAN) composite adsorbent

The inorganic phase, Na0.2Mo0.03W0.97O3 - ZH(2)O (MoHTB), which has been previously shown to be selective for Cs+ and Sr2+ from acidic radwaste simulants (0.075 mmol - L-1, 1.0 M HNO3) has been granulated with polyacrylonitrile (PAN) to afford a composite adsorbent suitable for deployment in small scale, fixed-bed columns. The uptake of Cs+ and Sr2+ by the MoHTB-PAN composites from such an acidic radwaste simulant is optimal for granular material of mesh size < 0.3 mm but satisfactory uptake rates are also observed with material of mesh size 0.3-0.63 turn. The fixed-bed column adsorption of Cs5(+) and Sr2+ from acidic radwaste simulant affords breakthrough curves which are of a typical 'S' shape profile but desorption of adsorbed Sr2+ by Cs+ in the radwaste simulant occurs after the composite column achieves equilibrium with respect to Sr2+. A simplified model of the adsorption of Cs+ and Sr2+ by the MoHTBPAN composite fixed-bed column has been applied to these initial results and has been shown to have utility in describing the performance of the fixed-bed column setup at the equimolar concentrations of Cs+ and Sr2+ employed.