GB2363999A - Method of separating a particle mixture using a biphasic system - Google Patents
Method of separating a particle mixture using a biphasic system Download PDFInfo
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- GB2363999A GB2363999A GB0015776A GB0015776A GB2363999A GB 2363999 A GB2363999 A GB 2363999A GB 0015776 A GB0015776 A GB 0015776A GB 0015776 A GB0015776 A GB 0015776A GB 2363999 A GB2363999 A GB 2363999A
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- separation chamber
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- B—PERFORMING OPERATIONS; TRANSPORTING
- B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
- B01D—SEPARATION
- B01D21/00—Separation of suspended solid particles from liquids by sedimentation
- B01D21/24—Feed or discharge mechanisms for settling tanks
- B01D21/2488—Feed or discharge mechanisms for settling tanks bringing about a partial recirculation of the liquid, e.g. for introducing chemical aids
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Abstract
A method of separating a particle mixture comprising first and second types of particle which differ chemically from each other, using a biphasic fluid system comprising a relatively dense first fluid and a relatively less dense second fluid, said fluids being substantially insoluble in each other. The particles PM to be separated and the two fluids are introduced into a separation chamber 10; the content of said chamber is allowed to settle to form an interface between said fluids; particles at the bulk interface are separated from particles near the bottom of the separation chamber - part of the settled material is discharged from 10 as a first stream H1 (denser fluid enriched with second-type of particles) into separation chamber 20, part of inter-phase material discharged as second stream L1 (less dense fluid enriched with first-type of particles) into separation chamber 30. The method is characterised in that: <UL ST="-"> <LI>at least the first fluid is a liquid; <LI>each particle can be found at the interface between said fluids in the absence of said other particle; <LI>the amount of particle mixture introduced into the separation chamber is chosen such that the ratio between the surface area of an interface formed when only the two fluids are present in the separation chamber while at rest and the smallest area occupied by the particles while in contact with a flat surface is & 1. </UL>
Description
2363999 UK 44401-Al/ho Method of separating a particle mixture The present
invention relates to a method of separ- ating a particle mixture comprising of a first type of solid particle and a second type of solid particle, both types dif- fering chemically from each other, using a biphasic fluid system consisting of a relatively dense first fluid and a relatively less dense second fluid which fluids are substan- tially insoluble in each other, wherein the particles to be separated and the two fluids are intro- duced into a separation chamber, the content of the separation chamber is allowed to settle and to form a bulk interface between the first fluid and the second fluid,-and particles at the bulk interface are separated from parti- cles near the bottom of the separation chamber.
Such a method is described by Winitzer S (Separ- ation Science 8 ( 6), p 647-659 ( 1973)) This theoretical pa- per described the separation of different solids of the same size or different sizes Both types of solid particles are denser than the first fluid Surface tension is exploited to overcome the gravity One type of particle will concentrate at the interface of the fluids, whereas the other type can be found at the bottom (in the first fluid).
The objective of the present invention is to provide a method of separating a particle mixture suitable for indus- trial scale In particular, an object of the present inven- tion is to provide an alternative for separation by size and/or density and to provide a method capable of separating in this respect physically nearly identical particles A fur- ther objective of the present invention is to provide a method capable of separating a mixture of solid particles wherein both types of particles to be separated have a ten- dency to accumulate at the interface.
To this end, the present invention is characterized in that at least the first fluid is a liquid, each type of particle has the property of that, in the absence of the other type of particle, it can be found at the interface be- tween the first fluid and the second fluid, and the amount of particle mixture introduced into the separation chamber is chosen such that the ratio between a) the surface area of an interface formed when only the two fluids are present in the separation chamber while at rest, and b) the smallest area occupied by the particles while in contact with a flat sur- face, is < 1.
Surprisingly, it has been found that it is possible to separate a particle mixture by providing the particles at a high concentration at the bulk interface Without desiring to be bound by any particular theory, it is thought that at a high particle concentration near the bulk interface, the par- ticles interact with each other, as a result of which the separation is effected Particles that may be separated are chromatographic resins, microbial cells, viruses, inclusion bodies, microbial RNA and DNA In the present invention, the term 'bulk interface' is intended to mean the interface be- tween the two fluids at a scale at least 5 times larger than the largest projected surface area of the largest particles of the mixture The bulk interface is generally a horizontal interface formed under the influence of gravity The first fluid is a liquid The second fluid may be a gas or a liquid.
As to the ratio (defined above), it is suitable < 0.35, preferably 0 1, and more preferably < 0 04.
A low ratio not only favours of the separation, but allows for the use of relatively small separation equipment as well This reduces the cost of the separation process.
In particular, the longest dimension of the par- ticles is in a range from 100 nm to 200 gm.
Particles within this size range apparently show good interaction with an interface and allow for an efficient separation.
According to a preferred embodiment the content of the separation chamber is mixed after which settling is al- lowed.
Mixing increases the interface area and thus allows for the use of relatively small separation equipment This reduces the cost of the separation process.
The particles in the particle mixture may be cry- stalline solid particles, in particular non-proteinaceous fermentation products Examples are antibiotics, aminoacids and peptides with up to 4 aminoacids.
These are good examples of product particles which may be separated from nearly identical by-product particles.
To achieve an efficient separation, first the fluids are introduced into the separation chamber, followed by the particles and mixing It is also possible first the first fluid is introduced into the separation chamber, followed by the particle mixture wetted by the second fluid and mixing.
For performing a separation on an industrial scale, it is advantageous that an apparatus (fig 2) is used com- prising a first separation chamber 10 into which a particle mixture (PM) is fed, and after performing a separation in said first separation chamber 10 at least a part of the settled material is dis- charged from the separation chamber 10 as a first stream Hi comprising relatively dense fluid enriched in the second type of particles, and at least a part of the inter-phase material is discharged from the separation chamber 10 as a second stream L 1 comprising relatively less dense fluid enriched in the first type of particles, wherein the first stream Hi is fed into a second separation chamber 20 and the second stream Li is fed into a third separation chamber 30, and, after per- forming separations in said second and third separation cham- bers 20, 30, at least a part of the settled material is dis- charged from the separation chamber 20 as a first stream H 2 comprising relatively dense fluid enriched in the second type of particles, and at least a part of the inter-phase material is discharged from the separation chamber 20 as a second stream L 2 comprising relatively less dense fluid enriched in the first type of particles, wherein the second stream L 2 is fed into the first separation chamber 10, and at least a part of the settled material is dis- charged from the separation chamber 30 as a first stream H 3 comprising relatively dense fluid enriched in the second type of particles, and at least a part of the inter-phase material is discharged from the separation chamber 30 as a second stream L 3 comprising relatively less dense fluid enriched in the first type of particles, wherein the first stream H 3 is fed into the first separation chamber 10.
This method may be regarded as a counter-current separation which, of course, may comprise more than the three separation chambers described here operated similarly to ob- tain highly purified streams enriched in one of the two types of particles.
The present invention will now be illustrated with reference to the following examples and the drawing, where Fig 1 depicts a graph showing inter-phase behaviour of a particle mixture with varying composition; and Fig 2 schematically depicts an apparatus suitable for working the method according to the present invention.
Example 1:
Initially 2 ml of water and 1 ml of butanol are mixed in a test tube with a minishaker at 1800 rpm for approximately seconds Phases are allowed to settle for 5 minutes Then mg of phenylglycine and 82 mg of ampicillin are added to the biphasic system Tube is shaked in a minishaker at 1800 rpm for approximately 10 seconds Phases are allowed to separate and particles to partition Some of the particles partition to the interface of the two liquids which results in the formation of an inter-phase layer ( 0 5 cm thick).
Also some particles will partition to the bottom phase and will form a sediment Samples are taken from the inter-phase layer and sediment in the bottom phase with the aid of a Pasteur pipette Samples are diluted in distilled water and analysed by HPLC From the HPLC data the concentrations of phenylglycine and ampicillin in the samples taken are obtained From these values the weight fraction of phenylglycine and ampicillin, XPG and Xapi respectively, in the inter-phase layer and sediment are determined as indicated below:
At the inter-phase:
(a) PG lPGl Mw(PG) Ampi lAmpil Mw(Ampi) where the concentration is expressed as mole/i.
(b) The weight fraction of phenylglycine, XG,, is:
PG/ XP PG P%/Ampi PG PG+Ampi 1 +PG/A / Ampi (c) The weight fraction of ampicillin, Xampi is: Xampi= 1-XPG At the sediment:
PG lPGl Mw(PG) Ampi lAmpil Mw(Ampi) (b) The weight fraction of phenylglycine, XPG, is:
PG/ X PG PG Ampi PG+Ampi 1 + PG pi (c) The weight fraction of ampicillin, Xampi, is: Xai= 1-XPG The results obtained were:
At the inter-phase:
5.83 151 (a) x-= 11 47 0.22 349 11.73 (b) 1 = O 92 1 + 11 73 (c) 1 0 92 = 0 08 At the sediment:
0.57 151 (a) x = O 15 1.62 349 0.15 (b) = O 13 1 + O 15 (c) 1 0 13 = 0 87 Example 2:
The experiment of Example 1 was repeated with 49 mg phenylglycine and 73 mg ampicilline The results obtained were:
At the inter-phase:
1.34 151 (a) x = 9 66 0.06 349 9.66 (b) O 91 1 + 9 66 (c) 1 0 91 = 0 09 At the sediment:
0.21 151 (a) -x = O 07 1.27 349 0.07 (b) = O 07 1 + 0 07 (c) 1 0 07 = 0 93 Example 3
The experiment of Example 1 was repeated using hexanol instead of butanol The amount of phenylglycine and ampicillin were 83 mg and 87 mg, respectively The results obtained were:
At the inter-phase:
3.62 151 (a) x = 31 32 0.05 349 31.32 (b) -32 = O 97 1 + 31 32 (c) 1 0 97 = 0 03 At the sediment:
0.31 151 (a) x = O 04 3.58 349 0.04 (b) = O 04 1 + 0 04 (c) 1 0 04 = 0 96 16 v: 4; Example 4
The experiment described in example 3 was repeated using 52 mg phenylglycine and 77 mg ampicillin The results obtained were:
At the inter-phase:
(d) 2 48 151 358 (d) x 349 = 3 58 0.3 349 (e) 3 58 = O 78 1 + 3 58 (f) 1 0 78 = 0 22 At the sediment:
(d) 12 x 351 = O 04 1.38 349 0.04 (e) -0 04 1 + 0 04 (f) 1 0 04 = 0 96 From the examples 1-4 it follows that a good separation can be achieved It also follows that the load (amount) of the mixture does not have a detrimental effect on the selectivity of the separation.
Example 5
A butanol/water system containing ampicillin and phenyl- glycine crystals was investigated as detailed below Earlier it was observed that the ratio between the amounts of the two types of crystals results in different type of inter-phase layers In case the majority of crystals added are ampicillin crystals, the interface layer extends towards the top phase, while the opposite is true in case the crystals are predomi- nantly phenylglycine Measuring how much of the top (butanol) and bottom (water) phases is occupied by the inter-phase layer gives us an estimate of the liquid composition of the inter-phase layer Note: the inter-phase layer is composed of a bottom phase, a top phase and ampicilline and phenylglycine crystals Figure 1 shows the results that were obtained af- ter such a measurement The ordinate shows the volume frac- 9 9:: 9 t 9 tion of top phase liquid in interfacial layer and the abcis shows the mass fraction PG crystals in added crystal mixture.
The system considered here is a butanol/water system ( 1 5 ml of water and 1 5 ml of butanol) to which a total amount of 0 044 g ampicillin and phenylglycin crystals are added The experimental procedure is as follows:
1.5 ml of water and 1 5 ml of n-butanol were added to a test tube with a Finn pipette The mixture was vortexed at a speed of 1800 rpm in a minishaker for 20 seconds and set aside to form two clear layers The position of the interface between the two liquids and the surface of the top phase were marked with a pen Crystalline D-phenylglycine and ampicillin-trihydrate were added such that the total mass of crys- tals was equal to 44 mg The mixture was vortexed for 30 sec- onds at a speed of 1800 rpm in a minishaker and set aside to form a clear top and bottom phases and an inter-phase layer (all the crystals adsorbed to the inter-phase, no crystals sedimented) This took typically 20 minutes The upper and lower interfaces of the inter-phase layer and the surface of the top phase were marked and the tube was emptied After that, the tube was rinsed with water and put in an oven to dry at 40 C After drying, water was added up to the marks on the tube and this was weighed; the weights were converted into volumes with a knowledge of the density of water From these values the volume of the top phase and the volume of the inter-phase layer before and after formation of the in- ter-phase layer were calculated The difference in volume of the top phase before and after formation of the inter-phase layer was considered to be equal to the volume of top phase in the inter-phase layer From a knowledge of the volume of top phase in the inter-phase layer and the volume of inter- phase layer, the volume fraction of top phase in the inter- phase layer is calculated as the ratio of these two volumes.
In figure 1 the mass fraction of phenylglycine crystals in the feed mixture against the volume fraction of top phase in the inter-phase layer is plotted The figure clearly shows that the solvent composition of the inter-phase layer is highly dependent on the type of crystals added In case the (r S: : ' S S S S - majority of crystals added are phenylglycine crystals the in- ter-phase layer mainly consists of bottom phase In this case we are probably dealing with a layer that is an emulsion of bottom phase droplets that are tightly squeezed together and surrounded by top phase For mass fractions of phenylglycine larger than 0 6 there does not seem to be an influence on the solvent composition of the layer anymore If most of crystals are ampicillin the opposite is observed Also the systems with predominantly ampicillin crystals gave quite unstable layers that desintegrated under the formation of a sediment after gently shaking the tubes.
Overall, figure 1 shows that the two crystals interact in different manner with the solvent system which is partly due to their differences in polarity This leads to differences in their interfacial partitioning which results in effective separation.
0; 0 a
Claims (10)
1 Method of separating a particle mixture compris- ing of a first type of solid particle and a second type of solid particle, both types differing chemically from each other, using a biphasic fluid system consisting of a rela- tively dense first fluid and a relatively less dense second fluid which fluids are substantially insoluble in each other, wherein the particles to be separated and the two fluids are intro- duced into a separation chamber, the content of the separation chamber is allowed to settle and to form a bulk interface between the first fluid and the second fluid, and particles at the bulk interface are separated from parti- cles near the bottom of the separation chamber, characterized in that at least the first fluid is a liquid, each type of particle has the property of that, in the ab- sence of the other type of particle, it can be found at the interface between the first fluid and the second fluid, and the amount of particle mixture introduced into the separation chamber is chosen such that the ratio between a) the surface area of an interface formed when only the two fluids are pre- sent in the separation chamber while at rest, and b) the smallest area occupied by the particles while in contact with a flat surface, is < 1.
2 Method according to claim 1, characterized in that the ratio is < 0 35, preferably 0 1, and more preferably < 0.04.
3 Method according to claim 1 or 2, characterized in that the longest dimension of the particles is in a range from 100 nm to 200 gm.
4 Method according to any of the preceding claims, characterized in that the content of the separation chamber is mixed after which settling is allowed.
Method according to any of the preceding claims, characterized in that the solid particles are crystalline : S: :@ O e ^ S S solid particles.
6 Method according to claim 5, characterized in that the crystalline particles are non-proteinaceous fermen- tation products.
7 Method according to any of the preceding claims, characterized in that first the fluids are introduced into the separation chamber, followed by the particles.
8 Method according to any of the preceding claims, characterized in that first the first fluid is introduced into the separation chamber, followed by the particle mixture wetted by the second fluid.
9 Method according to any of the preceding claims, characterized in that an apparatus is used comprising a first separation chamber 10 into which a particle mixture (PM) is- fed, and after performing a separation in said first separa- tion chamber 10 at least a part of the settled material is dis- charged from the separation chamber 10 as a first stream Hi comprising relatively dense fluid enriched in the second type of particles, and at least a part of the inter-phase material is discharged from the separation chamber 10 as a second stream L 1 comprising relatively less dense fluid enriched in the first type of particles, wherein the first stream Hi is fed into a second separation chamber 20 and the second stream Li is fed into a third separation chamber 30, and, after per- forming separations in said second and third separation cham- bers 20, 30, at least a part of the settled material is dis- charged from the separation chamber 20 as a first stream H 2 comprising relatively dense fluid enriched in the second type of particles, and at least a part of the inter-phase material is discharged from the separation chamber 20 as a second stream L 2 comprising relatively less dense fluid enriched in the first type of particles, wherein the second stream L 2 is fed into the first separation chamber 10, and at least a part of the settled material is dis- charged from the separation chamber 30 as a first stream H 3 comprising relatively dense fluid enriched in the second type of particles, and at least a part of the inter-phase material : 5 4: 5 is discharged from the separation chamber 30 as a second stream L 3 comprising relatively less dense fluid enriched in the first type of particles, wherein the first stream H 3 is fed into the first separation chamber
10.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| GB0015776A GB2363999A (en) | 2000-06-28 | 2000-06-28 | Method of separating a particle mixture using a biphasic system |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| GB0015776A GB2363999A (en) | 2000-06-28 | 2000-06-28 | Method of separating a particle mixture using a biphasic system |
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| Publication Number | Publication Date |
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| GB0015776D0 GB0015776D0 (en) | 2000-08-16 |
| GB2363999A true GB2363999A (en) | 2002-01-16 |
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| Application Number | Title | Priority Date | Filing Date |
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| GB0015776A Withdrawn GB2363999A (en) | 2000-06-28 | 2000-06-28 | Method of separating a particle mixture using a biphasic system |
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Cited By (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| WO2013059754A1 (en) * | 2011-10-20 | 2013-04-25 | Board Of Regents, The University Of Texas System | Continuous flocculation deflocculation process for efficient harvesting of microalgae from aqueous solutions |
Citations (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| GB866330A (en) * | 1956-03-06 | 1961-04-26 | Fischer Werner | A process for splitting up mixtures into their components by multiplicative distribution |
| GB2102301A (en) * | 1981-07-23 | 1983-02-02 | Norman Clark | Solids extraction process |
-
2000
- 2000-06-28 GB GB0015776A patent/GB2363999A/en not_active Withdrawn
Patent Citations (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| GB866330A (en) * | 1956-03-06 | 1961-04-26 | Fischer Werner | A process for splitting up mixtures into their components by multiplicative distribution |
| GB2102301A (en) * | 1981-07-23 | 1983-02-02 | Norman Clark | Solids extraction process |
Non-Patent Citations (1)
| Title |
|---|
| Separation Science, (1973), Vol. 8, p647-659 * |
Cited By (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| WO2013059754A1 (en) * | 2011-10-20 | 2013-04-25 | Board Of Regents, The University Of Texas System | Continuous flocculation deflocculation process for efficient harvesting of microalgae from aqueous solutions |
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| Publication number | Publication date |
|---|---|
| GB0015776D0 (en) | 2000-08-16 |
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