FR3059909A1 - SOLVENT EXTRACTION DEVICE WITH VISCOSITY VARIATION COMPENSATION AND ASSOCIATED EXTRACTION METHOD - Google Patents

Abstract

The invention is in the field of separative solvent partition chemistry. It relates to a solvent extraction system in parallel flows. According to the invention, the extraction system (10) comprises: a fluid exchange device (20) comprising a fluid exchange channel (213) arranged for channeling two liquid phases in parallel by putting them into contact with each other; one with the other, ▪ outlet capillaries (33, 34) each connected to an outlet of the fluid exchange device, the lengths of the outlet capillaries (33, 34) being determined so that the ratio of the length LB, capS of the second outlet capillary on the length LA, capS of the first outlet capillary is equal to the ratio of the flow rate QA of the liquid phase A to the flow rate QB of the liquid phase B multiplied by the ratio of the viscosity μA, capS of the liquid phase A at the outlet of the fluid exchange channel on the viscosity μB, capS of the liquid phase B at the outlet of the fluid exchange channel, so as to compensate for the viscosity variations of the liquid phases.

Description

Holder (s): COMMISSIONER OF ATOMIC ENERGY AND ALTERNATIVE ENERGIES Public establishment.

Extension request (s)

Agent (s): BREVALEX Limited liability company.

SOLVENT EXTRACTION DEVICE WITH COMPENSATION FOR VARIATIONS IN VISCOSITY AND RELATED EXTRACTION METHOD.

FR 3 059 909 - A1 (5 /) The invention relates to the field of separation chemistry by solvent sharing. It relates to a solvent extraction system in parallel flows.

According to the invention, the extraction system (10) comprises:

a fluid exchange device (20) comprising a fluid exchange channel (213) arranged to channel two liquid phases in parallel by bringing them into contact with each other, outlet capillaries (33, 34) connected each at an outlet of the fluid exchange device, the lengths of the outlet capillaries (33, 34) being determined so that the ratio of the length L _Bc „ _pS of the second outlet capillary to the length L _AC a _pS 'of the first outlet capillary is equal to the ratio of'cTebit Q _A of liquid phase A to flow Qp of liquid phase B multiplied by the ratio of viscosity μ _{Α Ç £} , _pS of liquid phase A at outlet of fluid exchange channel on the viscosity PBcçipS of the liquid phase B at the outlet of the fluid exchange channel, so as to compensate for the variations in viscosities of the liquid phases.

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SOLVENT EXTRACTION DEVICE WITH COMPENSATION FOR VARIATIONS IN VISCOSITY AND RELATED EXTRACTION METHOD

DESCRIPTION

TECHNICAL AREA

The invention relates to the field of chemical element analysis and, more specifically, to the field of separative chemistry by solvent extraction. It relates to a solvent extraction system comprising a device for contacting immiscible fluids in parallel flows and to a solvent extraction method using such an extraction system.

The invention is particularly applicable to the extraction of radionuclides, metals, polymers and brine, in the presence or absence of surfactants. It is of particular interest when at least one of the liquid phases has a viscosity value varying during the extraction.

PRIOR STATE OF THE ART

The chemical element analysis protocols currently used require the implementation of several stages of concentration, separation and purification. These operations may involve chemical risks, for example due to the presence of acids or solvents, and radiological risks, in the presence of radionuclides. The multiplicity of steps and the associated risks imply relatively long sample processing times and compliance with security constraints, for example carrying out operations in a glove box. The development of miniaturized systems, also called “lab-on-chip” or “lab-on-chip” in English, have made it possible to significantly improve the practical analysis of chemical elements at risk. Such a miniaturized system integrates several complex operations on a wafer whose surface is a few square centimeters. Downscaling brings many benefits. First of all, it allows a reduction in the quantities of reagents and samples analyzed, and consequently a reduction in the risk run by the operator in the event of handling dangerous products. In addition, thanks to shorter diffusion distances and the laminarity of the flows, the material transfers during the solvent extraction reaction are better controlled and faster. The analysis of a sample can also be reduced by the possibility of bringing together, on the same laboratory on a chip, several chemical operations (for example solvent extraction and de-extraction). Finally, the miniaturization of operations makes it possible to parallelize them either on the same miniaturized system or by connecting several systems in parallel.

More specifically, microsystem solvent extraction techniques have various advantages over conventional scale extraction techniques. First of all, they allow better control of flows and the interfacial area. The specific interfacial area is higher and the diffusion distances shorter which implies an acceleration of the sharing. In addition, in the case of parallel flows, they dispense with the decantation or centrifugation steps to separate the phases.

A parallel flow solvent extraction microsystem typically includes a fluid exchange microdevice formed in two assembled glass plates, one being etched before assembly to form, between two inlet ports and two outlet ports, two channels inlet, a fluid exchange channel and two outlet channels. A first inlet channel connects a first inlet port to an inlet of the fluid exchange channel and a second inlet channel connects the second inlet port to the inlet of the fluid exchange channel. A first outlet channel connects an outlet of the fluid exchange channel to a first outlet port and a second outlet channel connects the outlet of the fluid exchange channel to the second outlet port. The microdevice is then called the Y-Y junction microdevice. The extraction microsystem further comprises input and output capillaries for connecting the microdevice to other output devices, for example to detectors.

A first channel is formed between a first inlet capillary, connected to the first inlet port, and a first outlet capillary, connected to the first outlet port. This first lane allows circulation of a first phase. A second channel is formed between a second inlet capillary, connected to the second inlet port, and a second outlet capillary, connected to the second outlet port. This second lane allows circulation of a second phase. The fluid exchange channel constitutes an exchange interface for the phases flowing in parallel.

The two phases potentially have different viscosities. In order to obtain parallel flows of these two phases and individual recovery of the phases in the outlet channels, without contamination of one phase by the other, it is then necessary to play on the respective flow rates of the two phases. When the differences in viscosities between the two phases are too great, it is also necessary to play on an asymmetry of the microsystem between the first and the second path. In this case, a first solution consists in making the cross section of the fluid exchange channel of the microdevice asymmetrical. A second solution consists in modifying part of the surface of the fluid exchange channel. This solution however generates a complexification of the microdevice manufacturing process. In addition, this solution does not make it possible to maintain correct positioning of the interface at the outlet of the fluid exchange channel in the event of significant differences in viscosities between the two phases. A third solution consists in inserting pillars in the fluid exchange channel to stabilize the flows. However, the pillars reduce the exchange surface between the two phases. All these solutions involve a structural modification of the microdevice and therefore limit its use to a given pair of phase viscosities.

For the majority of the pairs of phases used in the chemical analyzes carried out in laboratory on a chip, the species to be shared is greatly diluted in one of the phases initially. The viscosity of the phases is mainly imposed by the chemical compositions of the phases, regardless of the presence or not of the species to be shared. However, for certain analyzes involving high concentrations of the species to be shared, the passage of this species from one phase to another generates a modification of the viscosity of each of the phases. Thus, a phase initially loaded with a compound with a given concentration of present entry into viscosity value of the microdevice p _betw een _e different from the viscosity at the outlet of the microdevice _fate p i _e as long as the compound concentration has changed at the transition to the other phase. The position of the interface is then modified, which potentially leads to poor separation of the output phases. The analysis (characterization) of the phases separately is then difficult. In extreme cases, the interface may even disappear.

The aforementioned solutions for maintaining parallel flow of the phases and separate recovery of the phases are therefore not entirely satisfactory in the case of extraction by solvent with a variation in the viscosity of the phases during the extraction. An object of the invention is therefore to propose a solvent extraction system with parallel flows making it possible to maintain good separation of the liquid phases at the outlet even in the event of variation in the viscosity of the phases.

STATEMENT OF THE INVENTION

To this end, the invention proposes a solvent extraction system with parallel flows in which the positioning of the interface at the outlet of the fluid exchange channel is adjusted by a modification of the dimensions of the outlet capillaries connected at the outlet of the microdevice. . Thus, a variation in the viscosities of the phases can be compensated without modification of the microdevice. In addition, the extraction system can be adapted to a large number of phase couples with different viscosities without modifying the microdevice.

More specifically, the subject of the invention is a solvent extraction system by bringing two immiscible liquids in parallel flows into contact, the extraction system comprising:

a fluid exchange device comprising:

o a first inlet orifice arranged to receive a flow of a liquid phase A, o a second inlet orifice arranged to receive a flow of a liquid phase B, the liquid phase B being more viscous than the liquid phase A , o a first outlet orifice arranged to evacuate the liquid phase A, o a second outlet orifice arranged to evacuate the liquid phase B, and o a fluid exchange channel connected at the inlet to each inlet and outlet at each outlet orifice, the fluid exchange channel being arranged to channel the two liquid phases A and B in parallel by bringing them into contact with each other, a first inlet capillary connected to the first inlet orifice , a second inlet capillary connected to the second inlet orifice, the dimensions of the inlet capillaries being identical, a first outlet capillary connected to the first outlet orifice, and a second outlet capillary connected to the second outlet orifice, the outlet capillaries having the same internal section, the extraction system being arranged so that the flow rate Q _A of the liquid phase A is greater than a minimum flow rate (^, _mm so as to obtain parallel flows of the liquid phases A and B, the extraction system being further arranged so that the ratio of the flow rate Q _B of the liquid phase B to the flow rate Q _A of the liquid phase A is equal to the ratio of the viscosity

JA. capE of the liquid phase A at the inlet of the fluid exchange channel on the viscosity

JB. capE of the liquid phase B at the inlet of the fluid exchange channel, the lengths of the outlet capillaries being determined so that the ratio of the length L _BcapS of the second outlet capillary to the length L _AcapS of the first outlet capillary is equal the ratio of the flow rate Q _A of the liquid phase A to the flow rate Q _B of the liquid phase B multiplied by the ratio of the viscosity p _AiCap s of the liquid phase A at the outlet of the fluid exchange channel to the viscosity p _BiCa ps of the liquid phase B at the outlet of the fluid exchange channel, so as to compensate for the variations in viscosities of the liquid phase A at the outlet of the fluid exchange channel and of the liquid phase B at the outlet of the fluid exchange channel.

Thus, the extraction system according to the invention must comply with the following conditions:

Qa - QA, min

Qb _ pA, capE

Qa b-B, capE ^ B.capS _ Qa · pA, capS M.capS Qb-Bb, capS

The conditions relating to the lengths of the outlet capillaries and to the flow rates of the liquid phases, in particular their ratio, ensure adequate operation of the extraction system, that is to say both of the parallel flows of the liquid phases A and B and an interface centered at the outlet of the fluid exchange channel.

The minimum flow rate Q _A , _m i _n of the liquid phase A can be determined experimentally for each pair of phases introduced at the input of the extraction system. The minimum flow rate Q _A , _m i _n is for example equal to 0.3 milliliter per hour (ml / h) in the case of the extraction of uranium by tributyl phosphate.

By way of example, for a solvent extraction system used for the extraction of uranium, the ratio Q _B / Q _A , obtained according to the already cited relation - = <2? I ^ Zis equal to 0.617.

l ^ B.capE

According to the invention, the variations in the viscosities of the liquid phases are compensated for by determining an appropriate ratio for the lengths of the outlet capillaries. More generally, these variations could be compensated for by modifying the ratio of their dimensions. In particular, the outlet capillaries could have the same length but separate internal sections, their ratio being adjusted to maintain the desired ratio Q _B / Q _A. Optionally, compensation for the variation in the viscosities of the two liquid phases at the outlet of the fluid exchange channel can be obtained by varying both the lengths of the capillaries and their internal section.

The inlet capillaries have identical dimensions. In particular, they have the same section and the same length: L _AcapE = L _BcapE .

The viscosity of each liquid phase is measured on a macroscopic scale before adapting the solvent extraction system. For the phases introduced into the inlet capillaries, the viscosities μ _Αιΰαρ Ε ^and PB.capE are measured on the phases directly. For the phases collected in outlet capillaries, the measurements of the viscosities pAiCaps ^and Fe.caps are carried out after having carried out a solvent extraction in batch and reaching equilibrium. Thus, the ratio of the flow rates QB / Q _A is determined by making the ratio of the viscosity μ _Αιΰαρ Ε of phase A at the inlet of the fluid exchange channel and of the viscosity μ _Βιΰαρ Ε of phase B at the inlet of channel d exchange, and the dimensions of the outlet capillaries are determined by taking into account the viscosity μ _Αιΰαρ 5 of the liquid phase A at the outlet of the fluid exchange channel and the viscosity μ _Βιϋα ρ5 of the liquid phase B at the outlet of the channel fluid exchange.

According to a particular embodiment, the fluid exchange device is arranged to generate an identical pressure loss for the liquid phases between, respectively, the first inlet orifice and the first outlet orifice, and the second inlet orifice and the second outlet.

The fluid exchange device may further include a first inlet channel connecting the first inlet port to an inlet of the fluid exchange channel, a second inlet channel connecting the second inlet port to the the inlet of the fluid exchange channel, a first outlet channel connecting an outlet of the fluid exchange channel to the first outlet port and a second outlet channel connecting the outlet of the fluid exchange channel to the second outlet port. The fluid exchange device then forms a double Y-junction device.

The fluid exchange device can constitute a microdevice, that is to say a device whose internal sections of the channels are less than or equal to the square millimeter, or even less than or equal to the square micrometer. In particular, the fluid exchange channel may have an internal section less than or equal to 1 square millimeter, preferably less than 5.10 ⁹ square meters.

According to a particular embodiment, the fluid exchange device comprises a first glass plate and a second glass plate. The fluid exchange channel is etched in at least one of the two glass plates and the two glass plates are assembled together to form a closed fluid exchange channel. The inlet and outlet channels can also be etched in at least one of the glass plates. Other materials can also be used, for example photocurable elastomers, thermoformable polymers (cyclic olefin copolymer), steels, ceramics.

The invention also relates to a solvent extraction process, in which an extraction system as described above is used.

The extraction process can in particular be used when at least one of the liquid phases has a viscosity varying during extraction, that is to say during the passage of a chemical species from one of the phases to the other phase.

The extraction process is for example applied to the extraction of uranium in a nitric medium by tributyl phosphate in n-dodecane.

BRIEF DESCRIPTION OF THE DRAWINGS

The invention will be better understood with the aid of the description which follows, given solely by way of nonlimiting example and made with reference to the appended drawings in which:

- Figure 1 shows schematically, in a three-quarter view, an embodiment of a solvent extraction microsystem according to the invention;

- Figure 2 shows, in a top view, a fluid exchange device of the microsystem of Figure 1;

FIG. 3 illustrates, by a photo microscope taken from above, a parallel flow of two liquid phases in the fluid exchange device of FIG. 2.

DETAILED PRESENTATION OF PARTICULAR EMBODIMENTS

Figure 1 shows schematically, in a three-quarter view, an embodiment of a solvent extraction microsystem according to the invention and Figure 2 shows, in a top view, a fluid exchange device of the microsystem . The extraction microsystem 10 comprises a fluid exchange device 20, a first inlet capillary 31, a second inlet capillary 32, a first outlet capillary 33 and a second outlet capillary 34. The exchange device fluidique 20 comprises a first glass plate 21 and a second glass plate, not shown in the figures. The two glass plates are arranged so that they can be assembled together, for example by welding or by gluing. In the first glass plate 21 are formed a first inlet channel 211, a second inlet channel 212, a fluid exchange channel 213, a first outlet channel 215 and a second outlet channel 216. In the second glass plate are formed a first inlet orifice 221, a second inlet orifice 222, a first outlet orifice 225 and a second outlet orifice 226. Each inlet and outlet orifice is arranged to receive a capillary d inlet or outlet capillary, respectively. The fluid exchange device 20 is arranged so that, once the glass plates are assembled, the first inlet channel 211 extends between the first inlet orifice 221 and an inlet of the fluid exchange channel 213, the second inlet channel 212 extends between the second inlet port 222 and the inlet of the fluid exchange channel 213, the first outlet channel 215 extends between an outlet of the fluid exchange channel 213 and the first outlet 225 and the second outlet 216 extends between the outlet of the fluid exchange channel 213 and the second outlet 226. The inlet channels 211 and 212 form a first Y junction with the fluid exchange channel 213 and the outlet channels 215 and 216 form a second Y junction with the fluid exchange channel 213. In this embodiment, the fluid exchange channel 213 extends longitudinally in a serpentine. Each channel has for example a width of 100 micrometers and a height of 40 micrometers.

The inlet capillaries 31 and 32 preferably have identical dimensions, that is to say the same internal section and the same length. Similarly, the inlet channels 211 and 212 preferably have dimensions which are identical to each other and the outlet channels have dimensions which are identical to each other. On the other hand, the outlet capillaries 33 and 34 have different dimensions, as a function of the viscosity of the two liquid phases circulating in the extraction microsystem 10, as explained below. A first channel is formed between an inlet of the inlet capillary 31 and an outlet of the outlet capillary 33. This first channel allows the circulation of a first liquid phase 41. A second channel is formed between an inlet of the inlet capillary 32 and an outlet of the outlet capillary 34. This second channel allows the circulation of a second liquid phase 42. The fluid exchange channel 213 allows a parallel flow of the two liquid phases and an exchange of chemical species of a phase liquid to the other liquid phase. One of the liquid phases is typically an organic phase and the other liquid phase an aqueous phase.

FIG. 3 illustrates, in a top view, a parallel flow of two liquid phases in the fluid exchange device 20. In this figure, the fluid exchange channel 213 is only partially represented. Due to the pressure conditions and the respective flow rates of the two liquid phases, a parallel flow can be observed. However, the interface 40 between the two liquid phases is not centered at the outlet of the fluid exchange channel 213. There follows a flow of the liquid phase 41 both in the outlet channel 215 and in the channel 216.

In order to correctly position the interface for individual recovery of two liquid phases A and B, the pressure within the two liquid phases must be balanced at the outlet of the fluid exchange channel 213. This balance can be expressed by the relationship :

àP _A = δρ _β (D where ΔΡ _α denotes the pressure difference within the liquid phase A between the inlet of the inlet capillary 31 and the outlet of the outlet capillary 33 and ΔΡ _Β denotes the pressure deviation within the liquid phase B between the inlet of the inlet capillary 32 and the outlet of the outlet capillary 34.

We can show that the relation (1) implies the following relation:

(2) where ΔΡ _{Α (; αρ5} denotes the pressure difference within the liquid phase A between the inlet and the outlet of the outlet capillary 33, and ΔΡ _{Β capS} denotes the pressure deviation within the phase liquid B between the inlet and the outlet of the outlet capillary 34.

Thus, an identical pressure can be observed at the outlet of the fluid exchange channel 213 between the two liquid phases A and B as soon as the outlet capillaries 33 and 34 generate the same pressure loss. The pressure loss generated by each capillary can be controlled by the dimensions of the capillary and / or by the flow rate of the liquid phase in this capillary. The Hagen-Poiseuille relation indicates:

(3)

where μ is the viscosity coefficient of the liquid phase, Q is the flow rate of the liquid phase, L is the length of the capillary and r is the radius of the capillary.

Relations (2) and (3) thus lead to the following relation:

Le.capS _ QA-PA, capS (4) ^L A, capS QB-PB.capS where Q _a and Q _b denote the flow rate in the liquid phases A and B respectively, p _AiCap s ^and 5 Be.caps denote respectively the viscosity values of the liquid phases A and B at the outlet of the fluid exchange channel 213 and L _AcapS and L _{B capS} denote the lengths of the outlet capillaries 33 and 34 respectively.

It should be noted that according to relation (4), by keeping the flow rate ratio Q _a / Q _b constant, the ratio L b, capsa, caps makes it possible to compensate for any change in value of the ratio of the viscosities of the two phases.

The inventors were able to test the invention for the extraction of uranium VI in a nitric medium by tributyl phosphate. The same microdevice could be used for a viscosity value of the aqueous phase of between 1.22 millipascal seconds (mPa.s) and 1.54 mPa.s and a viscosity value of the organic phase of between 1.97 mPa .s and 3.01 mPa.s, respectively. Thus, uranium VI could have an initial concentration in the aqueous phase up to 140 grams per liter (g / L). Without modification of the length of the outlet capillaries, parallel flows and a correct separation of the liquid phases would have been possible only for a viscosity value of the aqueous phase of 1.22 mPa.s and a viscosity value of the phase organic between 1.97 mPa.s and 2.24 mPa.s, i.e. a concentration of uranium VI less than 30 g / L.

Claims (7)

1. Solvent extraction system (10) by contacting two immiscible liquids (41, 42) in parallel flows, the extraction system comprising: a fluid exchange device (20) comprising: o a first inlet port (221) arranged to receive a flow of a liquid phase A, o a second inlet port (222) arranged to receive a flow of a liquid phase B, the liquid phase B being more viscous as the liquid phase A, o a first outlet orifice (225) arranged to evacuate the liquid phase A, o a second outlet orifice (226) arranged to evacuate the liquid phase B, and o a fluid exchange channel ( 213) connected at the inlet to each inlet port and at the outlet at each outlet port, the fluid exchange channel being arranged to channel the two liquid phases A and B in parallel by bringing them into contact with one other, a first inlet capillary (31) connected to the first inlet port (221), a second inlet capillary (32) connected to the second inlet port (222), the dimensions of the inlet capillaries being identical, a first outlet capillary (33) connected to the first outlet orifice, and a second capilla outlet line (34) connected to the second outlet orifice, the outlet capillaries having the same internal section, the extraction system being arranged so that the flow rate Q _A of the liquid phase A is greater than a minimum flow rate Q _A , _m i _n , so as to obtain parallel flows of the liquid phases A and B, the extraction system being further arranged so that the ratio of the flow rate Q _B of the liquid phase B to the flow rate Q _A of the phase liquid A is equal to the viscosity ratio PA. capE of the liquid phase A at the inlet of the fluid exchange channel on the viscosity PB. capE of the liquid phase B at the inlet of the fluid exchange channel, the lengths of the outlet capillaries (33, 34) being determined so that the ratio of the length L _{B capS} of the second outlet capillary to the length L _AcapS of the first outlet capillary is equal to the ratio of the flow rate Q _A of the liquid phase A to the flow rate Q _B of the liquid phase B multiplied by the ratio of the viscosity g _AiCa ps of the liquid phase A at the outlet of the fluid exchange channel on the viscosity p _Bc aps of the liquid phase B at the outlet of the fluid exchange channel, so as to compensate for the variations in viscosities of the liquid phase A at the outlet of the fluid exchange channel and of the liquid phase B at the outlet of the fluid exchange channel. 2. Extraction system according to claim 1, in which the fluid exchange device (20) is arranged to generate an identical pressure loss for the liquid phases A (41) and B (42) between, respectively, the first inlet port (221) and the first outlet port (225), and the second inlet port (222) and the second outlet port (226). 3. Extraction system according to one of claims 1 and 2, wherein the fluid exchange device (20) constitutes a microdevice, the fluid exchange channel (213) having an internal section less than or equal to 1 millimeter square, preferably less than 5.10 ⁹ square meter. 4. Extraction system according to one of the preceding claims, in which the fluid exchange device (20) comprises a first glass plate (21) and a second glass plate, the fluid exchange channel (213) being etched in at least one of the two glass plates, and the glass plates being assembled together to form a closed fluid exchange channel. 5. Solvent extraction method, in which an extraction system (10) according to one of the preceding claims is used. 6. Extraction method according to claim 5, wherein the liquid phases A and B have a viscosity varying during the extraction. 7. Extraction method according to one of claims 5 and 6, applied to the extraction of uranium in a nitric medium by tributyl phosphate in ndodecane. S.61324