TALSPEAK process on hollow fiber renewable liquid membrane apropos to the remedial maneuver of high level nuclear waste

Abstract

In concurrence with objectives of advanced high level nuclear waste(HLW) management, separation of chemically similar trivalent actinides and lanthanides is accomplished using TALSPEAK (Trivalent Actinide – Lanthanide Separation by Phosphorous reagent Extraction from Aqueous Komplexes) process on hollow fibre renewable liquid membrane (HFRLM). Permeability coefficient(Kf) of metal ions are determined under varying concentrations of diethylene triamine pentacaetic acid (DTPA) and H+ in the feed solution, containing 241Am with other metal impurities usually occurred in the HLW, and di(2-ethylhexyl) phosphoric acid (HDEHP) in liquid membrane and receiving emulsion phase. Optimized process conditions obtained are: 5 ± 0.25 L feed solution: containing 0.05 M DTPA, 1 M lactic acid and metal ions under the agitation of 400 ± 15 rpm, receiving phase: emulsion of 400 ± 15 mL 2 M HNO3 + 100 mL 0.2 M HDEHP/dodecane under stirring at 650 ± 25 rpm. The Kf of metal ions obtained under optimized process conditions are in the order: Am(III)<<Sm(III)<Nd(III)<Sr(II)<Pr(III)<U(VI) <Y(III)<Ce(III)<La(III). The maximum Kf = 9.24 × 10−3 cm min-1 is obtained for La(III) whereas Sm(III) with Kf = 7.4 × 10-4 cm min-1 is the most difficult lanthanide to separate from Am(III). For the single step process of HFRLM, the decontamination factor obtained for Am is 412. Agreement between Kf values, determined by model and experimental data are within 10 %.