METHOD AND DEVICE FOR CONTINUOUS COUNTERCURRENT TRANSFER OF MATERIAL BETWEEN TWO FLUID PHASES

Abstract

A method for continuous exchange of material includes countercurrent contacting of a first fluid phase and a second fluid phase that are not completely miscible. The contacting is carried out in a single centrifugal partition chromatography (CPC) apparatus into which only the first and second fluid phases introduced. The apparatus includes a plurality of cells, each with a stationary phase immobilized and a mobile phase passing through the stationary phase. The following steps are carried out successively: a) the mobile phase is formed by the first fluid phase, and the stationary phase immobilized in the cells is formed by the second fluid phase; b) the mobile phase is formed by the second fluid phase, and the stationary phase immobilized in the cells is formed by the first fluid phase; c) repetition of the succession of steps a) and b) each step being carried out immediately after the preceding step.

Claims

1. A method for continuous exchange of material by countercurrent contacting of a first fluid phase and a second fluid phase that are not fully miscible, wherein contacting is performed in a single apparatus, which is an apparatus of Centrifugal Partition Chromatography (CPC) apparatus type, into which only the first fluid phase and the second fluid phase are fed, excluding any other phase, said apparatus comprising a plurality of cells, with a stationary phase immobilised in each of the cells and a mobile phase passing through the stationary phase, and in that the following steps a), b), and c) are successively carried out: a) Step at which the mobile phase consists of the first fluid phase, and the stationary phase immobilised in the cells consists of the second fluid phase. b) Step at which the mobile phase consists of the second fluid phase, and the stationary phase immobilised in the cells consists of the first fluid phase. c) Repetition of the succession of steps a) and b); step b) being performed immediately after step a), and step c) being performed immediately after step b).

2. The method according to claim 1 wherein the apparatus, which is an apparatus of Centrifugal Partition Chromatography (CPC) apparatus type, comprises only two inlets for feeding phases into the apparatus, namely a first inlet through which the first fluid phase is fed into the apparatus, and a second inlet through which the second fluid phase is fed into the apparatus, and if the apparatus optionally further comprises one or more other inlet(s), this inlet (these inlets) is (are) not used to feed one or more other phase(s) into the device.

3. The method of claim 1, wherein the density of the first fluid phase is lower than the density of the second fluid phase, and step a) is then a step called step in ascending mode, and step b) is then a step called step in descending mode; or else the density of the first fluid phase is greater than the density of the second fluid phase, and step a) is then a step called step in descending mode, and step b) is then a step in called step in ascending mode.

4. The method according to claim 1, wherein the first fluid phase and the second fluid phase are independently selected from among liquid phases, gaseous phases, and supercritical phases.

5. The method according to claim 1, wherein the first phase is a liquid phase and the second phase is a liquid phase or a supercritical phase, or vice versa.

6. The method according to claim 5, wherein the first phase is a liquid phase containing a solute and the second phase is a liquid phase containing an extraction solvent for the solute or a supercritical phase acting as an extraction solvent for the solute, and at the end of step a) a liquid phase called solute-depleted raffinate is recovered, and at the end of step b) a liquid phase called solute-enriched extract is recovered or a supercritical phase called solute-enriched extract is recovered; or else the first phase is a liquid phase containing a an extraction solvent for a solute or a supercritical phase acting as an extraction solvent for a solute and the second phase is a liquid phase containing the solute, and at the end of step a) a liquid phase called solute-enriched extract is thus recovered or a supercritical phase called solute-enriched extract is thus recovered, and at the end of step b) a liquid phase called solute-depleted raffinate is recovered.

7. The method according to claim 5, wherein the first phase is a supercritical phase containing a solute and the second phase is a liquid phase containing an extraction solvent for the solute, and at the end of step a) a supercritical phase called solute-depleted raffinate is thus recovered, and at the end of step b) a liquid phase called solute-enriched extract is recovered; or else the first phase is a liquid phase containing an extraction solvent for a solute and the second phase is a supercritical phase containing a solute, and at the end of step a) a liquid phase called solute-enriched extract is thus recovered, and at the end of step b), a supercritical phase called solute-depleted raffinate is recovered.

8. The method according to claim 1, wherein the first fluid phase is a liquid phase and the second fluid phase is a gaseous phase, or vice versa, and a compound is transferred from one of the phases into the other phase.

9. The method according to claim 1, wherein the apparatus of Centrifugal Partition Chromatography (CPC) apparatus type comprises from 100 to 2000 cells.

10. The method according to claim 1, wherein the cells are symmetric.

11. The method according to claim 1, wherein each of the cells is divided into several sub-cells, for example two or three sub-cells, connected together via a channel.

12. The method according to claim 1, wherein the succession of steps a) and b) is repeated as many times as necessary to achieve the treatment of an entire volume of a feed phase, for example of a feed phase from which it is sought to extract the solute; preferably the succession of steps a) and b) is repeated from 1 to 300,000 times, more preferably from 1 to 100,000 times, better from 1 to 10,000 times, and still better from 1 to 1,000 times.

13. The method according to claim 1, wherein the time length of step a) is from 10 seconds to 120 seconds, preferably from 30 to 60 seconds and the time length of step b) is from 10 seconds to 120 seconds, preferably from 30 to 60 seconds.

14. The method according to claim 1, wherein the time length of step a) is equal to the time length of step b).

15. A device for carrying out the method according to claim 1, comprising: an apparatus of Centrifugal Partition Chromatography (CPC) apparatus type (31); a first tank (32) containing the first fluid phase (33); and a second tank (34) containing the second fluid phase (35); a first pipe (36) provided with a first pump, and a first valve (37), connecting the first tank (32) to a first inlet (39) of the apparatus of Centrifugal Partitioning Chromatography apparatus type (31); and a second pipe (310) provided with a second pump and a second valve (311), connecting the second tank (34) to a second inlet (313) of the apparatus of Centrifugal Partition Chromatography apparatus type (31); a third pipe (314) provided with a third valve (315), connecting the second inlet (313) of the apparatus of Centrifugal Partition Chromatography apparatus type (31) to a tank (316) intended to collect the first fluid phase, such as a liquid phase called raffinate (317), that has passed through the apparatus of Centrifugal Partition Chromatography apparatus type (31); a fourth pipe (318) provided with a fourth valve (319), connecting the first inlet (39) of the apparatus of Centrifugal Partition Chromatography apparatus type (31) to a tank (320) intended to collect the second fluid phase, such as a liquid phase called extract (321) that has passed through the apparatus of Centrifugal Partition Chromatography apparatus type (31); control means to actuate the opening and closing of the valves, to actuate the operation and stopping of the pumps, to synchronize the operation of the pumps and valves, to control the opening and closing times of the valves and the operation and stopping times of the pumps.

16. The device of claim 15, wherein the control means comprise a programmable logic controller that allows alternating and timed operation between: a first mode, preferably of determined time length, in which the first pump is in operation, the first valve is open, and the third valve is open, whilst the second pump is stopped, the second valve is closed, and the fourth valve is closed and; a second mode, preferably of determined time length, in which the second pump is in operation, the second valve is open and the fourth valve is open, whilst the first pump is stopped, the first valve is closed, and the third valve is closed.

17. The device according to claim 15, wherein the third and/or fourth pipe are provided with detection and/or analysis means such as UV, IR, or Raman detectors.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

[0194] FIG. 1 is a schematic view illustrating the principle of Centrifugal Partition Chromatography (CPC) in ascending mode, and of the first step a) of the method of the invention, called the ascending mode step.

[0195] FIG. 2 is a schematic view illustrating the principle of the second step b) of the method of the invention, called the descending mode step.

[0196] FIG. 3 is a schematic view of one embodiment of the device of the invention, for carrying out the method of the invention.

[0197] FIGS. 4A and 4B are a schematic view of another embodiment of the device of the invention for carrying out the method of the invention.

[0198] FIGS. 4A and 4B also illustrate operation in descending mode (FIG. 4A) and in ascending mode (FIG. 4B) at steps a) and b) of the device of these Figures, for carrying out the method of the invention.

DETAILED DESCRIPTION OF PARTICULAR EMBODIMENTS

[0199] In the following detailed description, embodiments of the device for carrying out the method of the invention are first described in detail, and the manner in which the method of the invention is carried out in these devices.

[0200] One embodiment of the device of the invention, for implementing, carrying out, the method of the invention, is described in a simplified manner in FIG. 3.

[0201] This device comprises: [0202] an apparatus of Centrifugal Partition Chromatography apparatus type such as a CPC column (31); [0203] a first tank (32) containing the first fluid phase (33), for example a liquid phase called feed phase or (solute)-rich phase which is for example an aqueous liquid phase, such as an aqueous solution containing a compound to be extracted, a solute such as a pollutant; [0204] a second tank (34) containing the second fluid phase (35), for example a liquid phase called solvent phase; [0205] a first pipe (36), equipped with a first pump (not shown) and a first valve R1 (37), connecting via pipe (38) the first tank (32) to a first inlet (39) of the apparatus of Centrifugal Partition Chromatography apparatus type (31); [0206] a second pipe (310), provided with a second pump (not shown) and a second valve R3 (311), connecting via pipe (312) the second tank (34) to a second inlet (313) of the apparatus of Centrifugal Partition Chromatography apparatus type (31); [0207] a third pipe (314), provided with a third valve R4 (315), connecting via pipe (312) the second inlet (313) of the apparatus of Centrifugal Partition Chromatography apparatus type (31) to a tank (316) intended to collect the first fluid phase such as a liquid phase called raffinate (317) that has passed through the apparatus of Centrifugal Partition Chromatography apparatus type (31). The raffinate is the feed phase that has been purified of the compound to be extracted i.e. of the solute, from which the solute has been extracted; [0208] a fourth pipe (318), provided with a fourth valve R2 (319), connecting via pipe (38) the first inlet (39) of the apparatus of Centrifugal Partitioning Chromatography apparatus type (31) to a tank (320) intended to collect the second fluid phase such as a liquid phase called extract (321) that has passed through the apparatus of Centrifugal Partitioning Chromatography apparatus type (31). The extract is the solvent phase enriched with the product to be extracted i.e. solute.

[0209] In the device of the invention, described in FIG. 2, a CPC contactor, apparatus is equipped with a set of valves R1 (37), R2 (319), R3 (311), R4 (315) controlled automatically to provide cyclic countercurrent operation of the CPC-type apparatus (31).

[0210] In this example of operation, the first liquid phase i.e. the solute-rich feed phase, has greater density than the second liquid phase i.e. the fresh solvent phase. The operation of the apparatus allows to cyclically reproduce the ascending mode in which the mobile phase is the second fluid phase, and the descending mode in which the mobile phase is the first fluid phase.

[0211] In practice, in ascending mode, valves R1 and R4 are closed and valves R2 and R3 are open, whereas in the descending mode, valves R2 and R3 are closed and valves R1 and R4 are open.

[0212] In the case when the feed phase has a lower density than the solvent phase, the operation is reversed: in the ascending mode valves R1 and R4 are open and valves R2 and R3 are closed, whereas in the descending mode valves R2 and R3 are open and valves R1 and R4 are closed.

[0213] The originality of the invention lies in the control of the cyclic operation (in particular cycle time) to reproduce counter-current operation with the desired theoretical plate number for a given separation.

[0214] A programmable controller (not shown) is used to drive the switching of the valves and to synchronize the operation of the pumps and valves.

[0215] Another embodiment of the device of the invention for implementing the method of the invention, is described in simplified manner in FIG. 4.

[0216] In this embodiment, it is to be understood that the feed phase has greater density than the solvent phase.

[0217] This device comprises: [0218] an apparatus of Centrifugal Partition Chromatography apparatus type, also called CPC contactor (41); [0219] a first tank (42) containing the first fluid phase (43), for example a liquid phase called feed phase F or (solutes)-rich phase or heavy phase which is for example an aqueous liquid phase such as an aqueous solution containing a compound to be extracted, a solute, such as a pollutant; [0220] a second tank (44) containing the second fluid phase (45), for example a liquid phase called solvent phase S′ or (solutes)-depleted phase or light phase, this phase may be fresh solvent for example to extract the solutes from the feed phase; [0221] a first line (46), equipped with a first pump P1 (47), connecting the first tank (42) to a first three-way valve EV1 (48). The first three-way valve (48) is connected to a first inlet (49) of the of Centrifugal Partition Chromatography apparatus (41) by a pipe (410); [0222] a second pipe (411), equipped with a second pump P2 (412), connecting the second tank (44) to a second three-way valve EV1 (413). The three-way valve (413) is connected to a second inlet (414) of the Centrifugal Partition Chromatography apparatus (41) by a pipe (415); [0223] a third pipe (416) connecting the second three-way valve (413) to a tank (417) intended to collect the first fluid phase such as a liquid phase called raffinate (418), that has passed through the Centrifugal Partition Chromatography apparatus (41). The raffinate R is the feed phase which has been purified of the compound to be extracted, i.e. the solute. [0224] a fourth pipe (419) connecting the first three-way valve (48) to a tank (420) intended to collect the second fluid phase, such as a liquid phase called extract E (421) that has passed through the Centrifugal Partition Chromatography apparatus (41). The extract (421) is the solvent phase enriched with the product to be extracted, i.e. solute.

[0225] Specific detectors, for example Raman, IR, or UV detectors (UV1 detector (422)), may be provided on the pipes (416) (UV1 detector (422)) and (419) (UV2 detector (423)) for continuous in-line analysis of solute concentration in the raffinate R and in the extract E.

[0226] A Programmable Logic Controller PLC (not shown) is used to control switching of the valves and to synchronize the operation of the pumps and of these valves.

[0227] The implementation of the method of the invention with the device shown in FIGS. 4A and 4B will now be described.

[0228] This implementation is described by way of example, particularly with respect to the implemented phases, and the man skilled in the art will easily be able to adapt the following description to any phase irrespective of type.

[0229] In FIG. 4A, circulation in descending mode takes place in the bold lines.

[0230] In FIG. 4B, the circulation in ascending mode takes place in the bold lines. [0231] the solute B of interest is dissolved in the feed phase F (43) found in the tank (42); [0232] pump P1 (47) allows to send the Feed F phase (43) into the CPC contactor (41); [0233] pump P2 (412) allows to send the extraction solvent S′ (45) from the tank (44) to the CPC contactor (41); [0234] at the outlet of the CPC contactor, the Feed F which has been depleted of solute B becomes the Raffinate phase R, and the Extraction Solvent S′ which has been enriched with solute B becomes the Extract phase E. The Raffinate phase R leaves the CPC contactor (41) through inlet (414), then through pipe (415), valve (413) and pipe (416). The extracted phase leaves the CPC contactor (41) through inlet (49), pipe (410), valve (48), and pipe (419); [0235] the CPC contactor (41) contains a number of cells Y. By convention, “Start of contactor” shall designate that part of the contactor located on the inlet side of the Feed phase (49) and on the outlet side of the Extract phase (49) (on top in FIGS. 4A and 4B). [0236] “End of contactor” shall designate that part of the contactor located on the inlet side of the Solvent phase (414), on the outlet side of the Raffinate phase (414) (At the bottom in FIGS. 4A and 4B). [0237] on start-up, the CPC contactor (41) is first filled with extraction solvent S′ by pump P2 (412). The contactor is rotated to the desired set value, and pump P1 (47) is then used to fill the CPC contactor with a given amount of feed phase (43) containing no solute. Typically, the man skilled in the art can adjust the ratio of solvent and feed phases in the contactor by acting on the rotation speed and the flow rate of feed phase used; [0238] the quantity of solvent S′ expelled due to filling of the CPC contactor (41) with the feed phase can be collected in a specific receiver or else in the main receiver Extract (tank 420).

[0239] Hydrodynamic equilibration of the CPC contactor is thus achieved. [0240] once the CPC contactor is stabilised, programming of the PLC is triggered. [0241] pump P1 (47) sends then a volume F1 of phase F (43) (containing the solute) over a given time (denoted Tcycle1) at the beginning (49) of the CPC contactor. Phase F is therefore the mobile phase feeding the CPC contactor. [0242] having regard to the densities in this example of implementation, this first cycle takes place in descending mode.

[0243] Simultaneously, valve EV1 (48) is positioned to allow the above-mentioned volume F1 to pass into the CPC contactor (41) through pipe (410), and valve EV2 (413) is positioned to send through lines (415) and (416) a phase of volume F1′, contained at the end of the CPC contactor, which is equivalent (or almost equivalent) to volume F1. This phase of volume F1′ is therefore expelled from the CPC contactor (41) towards the Raffinate receiver (417) via pipes (415) and (416).

[0244] At the beginning of the contactor, a feed volume F1 containing solute therefore passes through a number X1 of cells of the CPC contactor (41). [0245] After the cycle time Tcycle1 is completed, pump P1 (47) is stopped and pump P2 (412) is actuated. This pump P2 (412) sends then a given volume S1 of extraction solvent S′ (45) from the tank (44) to the end of the CPC contactor during a cycle time Tcycle1.

[0246] Simultaneously, valve EV2 (413) is positioned to allow the passing of a volume equivalent (or quasi-equivalent) to volume S1 in the CPC contactor (41), and valve EV1 (48) is positioned to allow the passing of a volume of solvent phase S1′ contained at the beginning of the CPC contactor (41), equivalent (or quasi-equivalent) to volume S1. This volume of solvent phase is thus expelled from the CPC contactor (41) towards the Extract receiver (420) via pipes (410) and (419). [0247] the solvent phase S′ then becomes the mobile phase in the CPC device and the feed phase becomes the stationary phase. The solvent volume S1 (421) expelled from the CPC contactor contains solute that has been extracted from the feed phase contained in the X1 cells.

[0248] On this second cycle, the device therefore operates in ascending mode, i.e. with the mobile phase lighter than the stationary phase. [0249] once T′cycle is completed, the operating cycle resumes under the conditions defined during Tcycle1 and the feed phase again becomes the mobile phase. Pump P1 (47) then fills X2 cells of the CPC with feed phase F (X2 may be equal to or different from X1 according to PLC programming), repelling towards the end of the CPC contactor the feed phase already contained in the X1 cells of the CPC contactor and which underwent extraction during Tcycle1; [0250] this alternating operation allows simulation of a countercurrent flow of phases F and S′. This alternating operation takes place until the entire feed volume F is treated; [0251] modelling the behavior of this device is possible for the man skilled in the art. This modelling allows the controller to be programmed so as to obtain the desired results; [0252] the influential input parameters which can be fed into the program of the controller are in particular: the volumes of F and S′ successively sent by the pumps, the operating times Tcycle and T′cycle (with of the possibility of having variable times during an operation), rotation speed, the geometry and the number of cells, the contactor volume, the initial stationary phase/mobile phase ratios, the system thermodynamics (partition coefficient of the solute, density and viscosity of the phases, interfacial tension . . . ); [0253] these input parameters and the very operating principle of the method of the invention allow the obtaining of a material transfer phenomenon, the result of which is extraction of the solute from the feed phase to the solvent phase; [0254] the input parameters and operation of the CPC contactor then define a theoretical plate number (TPN) value for extraction, a purification rate of solute from the Feed phase, and a solute extraction rate of the Solvent phase; [0255] in another operating configuration of the invention, the feed phase may be lighter than the solvent phase. The principle of the invention remains valid except that the feed phase is sent in ascending mode when it becomes the mobile phase and the solvent phase is sent in descending mode when it becomes the mobile phase; [0256] in another operating configuration of the invention, the CPC contactor may be initially thermodynamically equilibrated using a feed phase F containing solute.

[0257] The invention will now be described with reference to the following illustrative and non-limiting examples.

EXAMPLES

[0258] In the following Examples 1 to 6, the implementation of the method of the invention is described, with an installation according to the invention.

[0259] The installation used in the examples is similar to that described in FIGS. 1 and 2. This installation comprises a system of two G1/8 valves available from Bürkert®, Germany, controlled by a PLC (driven by Labview®). These valves are placed as close as possible to the rotary seals of the CPC apparatus.

[0260] When one of the valves is in the closed position, the other is in the open position.

[0261] Two AP-100 pumps, available from Armen®, France, allows the arrival of the feed and of the solvent into the CPC contactor.

[0262] The CPC contactor, CPC apparatus, is an EPC 300 column available from Kromaton®, France, having a volume of 280 mL and containing 231 asymmetric cells.

[0263] The raffinate and extract are recovered at the end of each test and assayed by UV spectrophotometry at 280 nm, using a Jasco® V630 dual beam spectrophotometer.

Examples 1, 2 and 3

[0264] In these examples, the tested phase system was the following: acetone (solute), heptane and water.

[0265] The feed phase F was the heptane phase containing the acetone to be extracted.

[0266] The extraction solvent S′ (solvent phase) was water.

[0267] The operating conditions were as follows: [0268] Rotation speed N of the CPC apparatus=800 rpm; [0269] F=48 mL/min of heptane at a concentration of 1.3 weight % acetone; and [0270] S′=12 mL/min of water containing no acetone.

[0271] The column, CPC contactor, was first hydrodynamically equilibrated with this liquid phase system.

[0272] At equilibrium, 60% of the CPC contactor volume was occupied by the aqueous stationary phase and 40% by the heptane phase, i.e. a retention of 60%.

[0273] The phases system described above was tested for 3 different cycle times, T Cycle, but each time with T cycle=T′ cycle.

[0274] These cycle times T Cycle were respectively 120 s., 60 s., and 30 s., for Examples 1, 2, and 3.

[0275] Under the experimental conditions used, the acetone partition coefficient K123 (i.e. the partition coefficient for Examples 1, 2, and 3) between the organic phase (feed phase) and the aqueous phase (solvent phase) was considered to be constant.

[0276] This partition coefficient Kin is given by the formula below (Foucault, A. P. Chromatographic Science Series In Centrifugal Partition Chromatography; Marcel Dekker: New York, 1995; Vol. 68):

[00001]$K_{123}=4\frac{\mathrm{kg}\mathrm{acetone}\text{/}L\mathrm{feed}\mathrm{phase}}{\mathrm{kg}\mathrm{acetone}\text{/}L\mathrm{solvent}\mathrm{phase}}$

[0277] The results obtained are grouped together in following Table I:

TABLE-US-00001 Solute extraction rate by weight XBF XBR (1 - XBR/XBF) F (mL/min) S (mL/min) T Cycle(s) T′ Cycle(s) (weight %) (weight %) (weight %) NTP 48 12 120 120 1.3 0.07 94.62% 17.6 48 12 60 60 1.3 0.06 95.38% 20.7 48 12 30 30 1.3 0.03 97.69% 42.3

[0278] The flow rates of the two phases were selected for operation with a separation factor ε=K.Math.S/F=1, a conventional operating configuration.

[0279] The NTP value was calculated based on liquid/liquid extraction theory discussed below and with a separation factor of 1, leading to the following simplified formula TPN=(X.sub.F−X.sub.n)/X.sub.n.

[0280] The experimental results illustrate the proper functioning of the method of the invention.

[0281] The CPC contactor allowed between 17 and 42 theoretical extraction plates to be achieved (solute extraction rate with respect to the feed of between 94 weight % and 97 weight %). The use of short cycle times enabled the contactor to operate under conditions increasingly closer to a true continuous countercurrent. Use of a CPC contactor having more cells would allow even higher TPN values to be obtained.

Examples 4, 5 and 6

[0282] In these examples, the phase system tested was the following: acetone (solute), heptane and water. In these examples, the feed phase F consists now of the water phase which therefore contains acetone, and the extraction solvent S′ (solvent phase) was pure heptane.

[0283] The operating conditions were the following: [0284] rotation speed of N of the CPC device=800 rpm, [0285] F=12 mL/min of water containing acetone; and [0286] S′=48 mL/min of heptane containing no acetone.

[0287] The CPC contactor was hydrodynamically equilibrated with this liquid phases system.

[0288] At equilibrium, the retention obtained was 40%, i.e. 40% of the contactor volume was occupied by the heptane stationary phase.

[0289] The phase system described above was tested for 3 different cycle times, T Cycle.

[0290] These cycle times, T Cycle, were respectively 120 s., 60 s., and 30 s., for examples 1, 2, and 3.

[0291] These cycle times, T Cycle, were respectively 120 s., 60 s., and 30 s., for examples 1, 2, and 3.

[0292] In the configuration of these Examples 4, 5, and 6, in which the solvent and feed phases were modified when compared to Examples 1, 2, and 3, the partition coefficient K456 (i.e., partition coefficient for Examples 4, 5, and 6) was now the reverse of that defined above, namely:

[00002]$K_{456}=0.25\frac{\mathrm{kg}\mathrm{acetone}\text{/}L\mathrm{Feed}\mathrm{phase}}{\mathrm{kg}\mathrm{acetone}\text{/}L\mathrm{Solvent}\mathrm{phase}}$

[0293] To obtain a similar separation configuration, the flow rates were modified to maintain a separation factor E of 1.

[0294] The results obtained are grouped together in following Table II:

TABLE-US-00002 Solute extraction rate by weight XBF XBR (1 - XBR/XBF) F (mL/min) S (mL/min) T Cycle (s) T′ Cycle (s) (weight %) (weight %) (weight % ) NTP 12 48 120 120 5.3 0.7 86.79 6.6 12 48 60 60 5.41 0.61 88.72 7.9 12 48 30 30 5.3 0.56 89.43 8.5

[0295] The NTP value was calculated based on the liquid/liquid extraction theory and with a separation factor of 1, which leads to the following simplified formula TPN=(X.sub.F−X.sub.n)/X.sub.n.

[0296] In this case, the CPC contactor allowed between 6 and 8.5 theoretical extraction plates to be obtained (extraction rate of solute in relation to feed of between 86 weight % and 89 weight %).

[0297] The results were not as good as those obtained in the previous Examples 1, 2, and 3. The use of short cycle times enabled the contactor to operate under conditions increasingly closer to a continuous countercurrent.

[0298] Use of a CPC contactor with more cells would allow higher TPN values to be obtained.

[0299] Several hypotheses can be set forth to account for the less good results in this configuration of Examples 4, 5, and 6:

[0300] 1—the retention of the stationary phase in the second case (heptane) is lower (40% instead of 60%) leading to less good contacting between the phases;

[0301] 2—the flow of the dispersed droplets in the cells is less favorable in the second case. This difference in flow may be related to the asymmetry of the cells in the device used here.