A highly efficient supported liquid membrane system for near quantitative recovery of radio-strontium from acidic feeds. Part II: Scale up and mass transfer modeling in hollow fiber configuration

The transport behaviour of radio-strontium from acidic feed solutions was investigated using 4,4′(5′)di-tert-butyl-dicyclohexano-18-crown-6 (DTBCH18C6) as the carrier extractant employing the hollow fiber supported liquid membrane (HFSLM) technique. The results indicated 92% transport of the metal ion from 3 M HNO3 feed solution in 3 h of continuous operation in recycling mode using an improved solvent system consisting of 0.1 M DTBCH18C6 in 80% NPOE + 20% n-dodecane which was remarkably superior to the previously reported solvents for Sr(II) separation from acidic feeds. Crown ether assisted acid co-transport was found to be quite significant in such cases which resulted in Sr(II) back transport. The neutralization of acidity by addition of NaOH indicated alleviation of the back transport of Sr(II) and a near saturation transport value was noticed.Studies on the Sr(II) transport from pressurized heavy water reactor-simulated high level waste (PHWR-SHLW) solution indicated comparable transport profiles with that obtained using 3 M HNO3 as the feed. Hydrogen ion effect on Sr(II) transport was investigated using feed solutions containing a fixed nitrate concentration with varying H+ ion concentration. A mathematical model was used for the simulation of transport behaviour of metal through the membrane.

► Sr(II) transport from acidic feeds was studied using DTBCH18C6.
► HFSLM technique was used for scale up at 0.5 L scale.
► 94% transport was seen from simulated HLW solution.
► Mathematical modeling was also carried out.