Sequential separation of lanthanides, thorium and uranium using novel solid phase extraction method from high acidic nuclear wastes

A novel grafted polymer for selective extraction and sequential separation of lanthanides, thorium and uranium from high acidic wastes has been developed by grafting Merrifield chloromethylated (MCM) resin with octyl(phenyl)-NN-diisobutylcarbamoyl-methylphosphine oxide (CMPO) (MCM-CMPO). The grafting process is well characterized using FT-IR spectroscopy, P-31 and C-13 CPMAS (cross-polarized magic angle spin) NMR spectroscopy and CHNPS elemental analysis. The influence of various physico-chemical parameters during metal ion extraction by the resin phase are studied and optimized by both static and dynamic methods. The resin shows very high sorption capacity values of 0.960 mmol g(-1) for U(VI), 0.984 mmol g(-1) for Th(IV), 0.488 mmol g(-1) for La(III) and 0.502 mmol g(-1) for Nd(III) under optimum HNO3 medium, respectively. The grafted polymer shows faster rate exchange kinetics (< 5 min is sufficient for 50% extraction) and greater preconcentration ability, with reusability exceeding 20 cycles. During desorption process, sequential separation of the analytes is possible with varying eluting agents. The developed grafted resin has been successfully applied in extracting Th(W) from high matrix monazite sand, U(VI) and Th(W) from simulated nuclear spent fuel mixtures. All the analytical data is based on triplicate analysis and measurements are within 3.5% rsd reflecting the reproducibility and reliability of the developed method. (c) 2006 Elsevier B.V. All rights reserved.