A novel solid phase extraction method for separation of actinides and lanthanides from high acidic streams

A novel solid phase extractant has been developed by grafting Merrifield chloromethylated resin (MCM) with N,N-di-hexyl succinamic acid (DHSA). The grafting process is confirmed by 13C CPMAS NMR spectroscopy, FT-IR spectroscopy, and also by CHN elemental analysis. All the parameters influencing the quantitative metal ion extraction were optimized by both static and dynamic methods. This polymeric sorbent shows greater selectivity in extracting U(VI), Th(IV) over lanthanides from highly acidic matrices. Maximum sorption capacities were observed at 4 M HNO3 for U(VI) and Th(IV) where as for La(III) and Nd(III) it is at 2 M HNO3. Quantitative metal desorption has been achieved by using 0.5 M (NH4)2CO3 for all the analytes. The grafted polymer showed faster phase exchange kinetics (<5 min is sufficient for 50% extraction) and greater preconcentration ability with reusability exceeding 30 cycles. The resin showed non-extractive behavior for all transition metal ions along with various diverse ions that are commonly present in nuclear spent fuel solutions. The practical utility in selectively separating U(VI), Th(IV) from rare earth ions has been tested using synthetic low level nuclear reprocessing mixture. Analytical data obtained from both batch and column studies are within 3.5% relative standard deviation (R.S.D.) based on triplicate measurements, thereby reflecting the reproducibility and reliability of the developed method. © 2006 Elsevier B.V. All rights reserved.