Evaluation of plutonium(IV) extraction rate between nitric acid and tri‐n‐butylphosphate solution using a glass chip microchannel

Abstract

Extraction of Pu(IV) with tri-n-butylphosphate is performed using a glass chip microchannel to evaluate the extraction rate. Two-phase flow forms in the microchannel by introducing a solution of Pu(IV) and tri-n-butylphosphate with flow rates above 5 μL/min. The Pu(IV) extraction reaction proceeds at the interface between the two phases. To evaluate the extraction rate, the contact time between the two phases is varied from 0.48 to 4.8 s by changing the confluent length of the microchannel and the flow rate. The Pu concentration of each phase collected from the microchannel is measured with an alpha liquid scintillation counter, and the contact time dependence of Pu(IV) extraction is obtained. An extraction model based on diffusion in the microchannel and the reaction at the interface is proposed and applied to determine the extraction rate. The extraction process is assumed to follow pseudo-first-order kinetics, and the extraction rate constant of Pu(IV) is determined to be 1.5 × 10(-2) cm/s. The investigation demonstrates that a microfluidic device can be a new tool to determine Pu(IV) extraction rates.

Microfluidic solvent extraction of rare earth elements from a mixed oxide concentrate leach solution using Cyanex® 572

“…Microfluidic devices are being explored as an alternative approach for solvent extraction, including droplet and stream-based extraction chips [10]. Microfluidic solvent extraction has been reported for liquid-liquid extraction of Ag [11], Co [12,13], Cu [14][15][16][17], Cr [16], Pt [18,19], Pd [19], and various lanthanides [20][21][22][23] and actinides [24][25][26]. As with bulk SX, increasing the surface-tovolume (S/V) ratio in microfluidic extraction increases the rate of extraction [10,19,23,24,27].…”

Experimental Methodology for Kinetic Acquisitions Using High Velocities in a Microfluidic Device

“…Some authors are now using microfluidics to study mass transfer in the nuclear field [9][10][11][12] and fewer attempts exist to determine the intrinsic constants governing it [13,14]. They are characterized by the absence of a diffuse layer [15].…”

“…Up to now, the vast majority of the kinetic studies in two-phase flow using microfluidic channels employs segmented flows. Some studied stratified flows [11,[16][17][18], although this configuration eases the phase separation at the outlet of the channel. Moreover, unlike segmented flows, the hydrodynamics in laminar stratified flows can follow a Poiseuille-like profile.…”

Solid-phase extraction microfluidic devices for matrix removal in trace element assay of actinide materials

“…With the advent of low-flow nebulization and loop injection techniques for plasma spectroscopy, it is now possible to perform comprehensive, high-sensitivity actinide impurity assay by ICP-OES using just 1 mL of column effluent [8]. Although microfluidic technology for actinide separation is still in its infancy [9][10][11][12], integrated microfluidic devices customized with solid-phase resins hold significant potential as lab-on-a-chip platforms for matrix removal in trace element assay and for related analyses of actinides. An effective microfluidic separation device would support a 10-to 100-fold reduction in sample size, with commensurate operational benefits to worker safety and waste minimization.…”