Transport of Pu(IV) across supported liquid membrane from nitric acid medium using cyanex -923 as the mobile receptor

Abstract

Based on the solvent extraction data, experiments were conducted with Flat-sheet Supported Liquid Membrane (FSSLM) to examine the transport behaviour of Pu(IV) to achieve its maximum recovery. This is necessary to optimize the conditions for further operation of Hollow Fiber Supported Liquid Membrane (HFSLM) and Compact Supported Liquid Membrane Flow Cell (CSLMFC). A laboratory scale hollow fiber module, having membrane surface area, 134 cm², was employed in a recycling mode using 'Enka' Accurel hollow fiber polypropylene membranes as the solid support, cyanex-923 as the mobile receptor and dodecane as the membrane solvent. Dilute plutonium nitrate solutions in 1M HNO₃ generally constituted the source phase. Among the

strippants, several reagents were tried, the most efficient strippant found was dilute uranous solution in 1.0 M HNO₃. The recovery of Pu from the Pu oxalate supernatant generated during Pu reconversion operations in the PUREX process was tried, where it was observed that ~94% of Pu(IV) could be transported in a single run of duration of 10 h, while employing 0.1 M cyanex-923/dodecane as a mobile receptor and uranous solution in 1.0 M HNO₃ as the strippant. Parameters such as source phase concentration, source and strippant phase recirculation flow rate, concentration of carrier in the membrane and strippant, and interferences of other permeants on plutonium permeation pertaining to FSSLM, HFSLM and CSLMFC were optimized.<br>

This followed the utilization of more application oriented configuration i .e. Hollow fiber membrane configuration for the above purpose.<br> With HFSLM, the <i>K</i>_obs values increased from 3.06×10^-5 to 6.27 × 10^-5 s^-1 by increasing now rate from 0.03 × 10^-6 to 0.14×10^-6 m³/s at 1 h and the percentage permeation increased from 75 to 90%. In the case of CFSLMC, the <i>K</i>_obs increased from 5.41 × 10^-5 to 5.74× 10^-5 s^-1 while increasing flow rate from 0.27× 10^-6 to 0.42×10^-6 m³/s at 1 h and the percentage permeation increased from 65 to 85% .