Studies on mass transfer of europium(III) in micro-channels using a micro Laser Induced Fluorescence technique

Abstract

The mass transfer of europium(III) from an aqueous to an organic phase was studied in a quartz microchannel (internal diameter of 200 μm) using a novel micro Laser Induced Fluorescence (micro-LIF) technique. Europium(III) was extracted from a 1M nitric acid solution into an organic solution of TBP(1.2M)/CMPO(0.2M) in Exxsol D80. For the flow rates investigated plug flow was established. An experimental and data processing methodology was developed to calculate concentration profiles from the fluorescing light intensity profiles in both phases at different locations along the microchannel. In particular, the effect that the high light intensity of the organic phase has on the measurements in the aqueous phase was taken into account. Mass transfer was found to be significant in the beginning of the channel close to the inlet (1 mm distance) with extraction percentages varying between 20 to 40% depending on the total flow rate. High extraction efficiency (~80%) was achieved at short residence times (in the first 6 s), while the overall volumetric mass transfer coefficients varied between 0.05 and 3.3 s-1 .

Continuous Extraction of Europium(III) by Ionic Liquid in the Rotating Disk Column with an Asymmetrical Structure Aimed at the Evaluation of Reactive Mass Transfer

“…Limited research has been reported by examining the supported liquid membranes 24 − 27 and microchannels to intensify the extraction process. 28 − 30 …”

Scale-Up Studies for Co/Ni Separations in Intensified Reactors

“…Even though the increase in total flowrate resulted in higher specific interfacial areas due to smaller plug lengths, the plug formation time decreased, resulting in less contact time of the phases in the mixing zone. Previous studies have shown that the effect of mixing zone on the overall extraction efficiency of the reactor contributes from 25 to 40% depending mainly on the flowrate ratio, the total flowrates, and the channel size [ 13 , 16 , 31 ].…”

“…For example, for a constant flowrate, i.e., 1.6 mL/min, the extraction percentage increases 2.5 times when the channel size increases from 1 to 2 or 3.2 mm. This is mainly attributed to the fact that during plug flow, a large percentage (~35%) of mass transfer takes place during plug formation in the mixing zone [ 13 , 15 ]. It can also be seen that Ni(II) was not co-extracted in all cases, in agreement with the equilibrium results.…”

“…At the lower bound of mixture velocities (u mix = 0.0042 m/s), the extraction performance is similar for all channel sizes. This is attributed to the fact that for a constant mixture velocity, the formation of the plug in the T-junction takes longer as the channel size increases, and a considerable amount of mass transfer takes place in the mixing zone [ 13 , 15 ]. The differences in extraction for the various channel sizes are larger than the experimental error.…”

“…New intensified technologies can provide faster, cheaper, and greener processes [ 10 ]. In recent years, intensified units where two immiscible liquids are involved have attracted much attention in process engineering for the separation, purification, and recycling of precious metals [ 11 , 12 ], rare earth metals [ 13 , 14 ], and actinides [ 15 , 16 , 17 , 18 ]. A common intensification approach involves the use of small channels, where thin fluid films form that decrease the diffusion distances and increase the mass transfer rates.…”