FR3082756A1 - PROCESS FOR SEPARATING IONIZED MOLECULES IN A CONTAINING SOLUTION - Google Patents

Abstract

The subject of the invention is a process for the separation of at least one ionized molecule from at least one non-ionized molecule in a solution comprising at least one ionized molecule and at least one non-ionized molecule, characterized in that it This is a continuous ion exclusion chromatography process implemented with one or more anionic resin (s).

Description

PROCESS FOR SEPARATING IONIZED MOLECULES IN A SOLUTION CONTAINING

The invention relates to the separation of ionized molecules from non-ionized molecules in solutions, by ion exclusion chromatography.

Ion exclusion chromatography is a process used for many years industrially for the separation of ionized molecules (organic and mineral salts) in particular for the purification of sugar molasses, distiller vinasse, polyol solutions from the synthesis from sugars and a strong base, for the separation of a salt and an undissociated acid.

Currently, all separation techniques by ion exclusion chromatography are used on cationic resins having a sulfonated polystyrene structure.

This is the case, for example, of application FI882740 which describes a chromatographic method of ion exclusion to recover betaine from beet molasses by applying a principle of ion exclusion on cationic resin. This is also the case for application US2016325232 which describes a method of recovering glycerol by exclusion chromatography from distillery vinasse or also EP1978009 which mentions the recovery of glycerol from the production of biodiesel. In all these cases, the type of resin is a strong cationic resin in the form of Na.

The characteristic of this technique, the principle of which is presented in Figure 4, is that the sign of the electric charge of the dissociated functional groups on the ion exchanger is the same as that on the injected ionic compound. It follows that negatively charged ions are separated on cation exchange resins.

This electrical repulsion effect requires that the ions located in the stationary phase be perfectly solvated and therefore that this phase is more concentrated in ions than the mobile phase, which keeps the swelling of the stationary phase at its maximum by osmosis effect. If the concentration of the mobile phase is greater than that of the stationary phase, we will then observe a contraction effect of the stationary phase which will expel the solvent to find an ionic concentration close to that of the mobile phase. The nonionic molecules which diffuse in the stationary phase without being excluded will see the accessible volume of the stationary phase reduced and thus the quality of the separation will decrease.

This is why this separation technique, however widely described and used, does not allow good yields, the purity of the separated molecules is not sufficient and it is necessary to reload the resins during the process which does not is not practical, not economical and a source of error.

The objective of the invention is to propose a process which answers these problems and in particular an industrial process for the separation of ionized molecules in a solution containing it, which has a better yield than the chromatographic process of exclusion of existing ion , which improves the separation, which makes it possible to obtain better purity of the separated molecules and which is practical and simple to implement.

To answer this question, the invention relates to a process for the separation of at least one ionized molecule from at least one non-ionized molecule in a solution comprising at least one ionized molecule and at least one non-ionized molecule, characterized in that it s 'is a continuous ion exclusion chromatography process implemented with at least one anionic resin.

Surprisingly and advantageously, such a method makes it possible to overcome all the problems encountered with a method of ion exclusion chromatography implemented on a cationic resin.

The invention therefore also relates to the use of this process for the separation of ionized molecules from non-ionized molecules in sugar molasses, biodiesel glycerol, whey and whey permeates, biological juices, solutions of salts and acid.

The invention is now described in detail with reference to the appended figures in which:

FIG. 1 represents the results obtained from the tests (point 2.2) corresponding to the sugar profiles on anionic resin and on cationic resin; the sucrose profile is more concentrated and less dispersed with the anionic resin than with the cationic resin;

FIG. 2 represents the results obtained from the tests (point 2.2) corresponding to the profiles of the non-sugars on anionic resin and on cationic resin; the peak of non-sugars is more concentrated and less spread with the anionic resin than with the cationic resin;

FIG. 3 represents the results obtained from the tests (point 2.2) corresponding to the profiles of betaine on anionic resin and on cationic resin; the betaine peak is more concentrated and less spread with the anionic resin than with the cationic resin.

Figure 4 the principle of ion exclusion with the formation of the "Donnan membrane"

In Figures 1 to 3, the letter "z" means "area".

Definitions

By “ionized molecule” or “ionic compound” within the meaning of the invention means a molecule or compound constituted by one or more ions whether it is a mineral element (for example Na ⁺ ) or organic (for example HCOOj. An ion is a chemical species that has lost or gained an electron. Conversely, an "un-ionized molecule" or a "non-ionic compound" is an uncharged molecule or compound, containing no ions.

By "strong anionic resin" within the meaning of the invention means a resin having a majority of active sites of quaternary ammonium type

By “weak anionic resin” within the meaning of the invention is meant a resin having a majority of active sites of ternary ammonium type.

By “uniformity coefficient” within the meaning of the invention is meant the ratio of the particle diameters of the population of resin beads between the 60% of the smallest particles of the population of beads and the 10% of the most small of the log population.

Detailed description of the invention

The subject of the invention is therefore a method of separating at least one ionized molecule from at least one non-ionized molecule in a solution comprising at least one ionized molecule and at least one non-ionized molecule.

The process according to the invention is a continuous ion exclusion chromatography process implemented with one or more anionic resin (s), that is to say implemented on one or more resin ( s) anionic.

The ionized molecule (s) or ionic compound (s) present in the solution and which one seeks to separate from the non-ionized molecule (s) present ( s) in the solution is (are) preferably chosen from mineral salts, organic salts or a mixture. Thus the solution comprises at least one mineral salt, an organic salt or a mixture of one or more mineral salt (s) and one or more organic salt (s).

The solution in which it is desired to separate the molecules of at least one ionized molecule from at least one non-ionized molecule, can be any solution containing at least one ionized molecule and at least one non-ionized molecule. They are preferably sugar molasses, biodiesel glycerol, whey and whey permeates, organic juices, solutions of salts and acids.

The method according to the invention is preferably a method of continuous ion exclusion chromatography against the current of the simulated moving bed or sequenced simulated moving bed type. It can also be a continuous co-current ion exclusion chromatography process.

The process is generally carried out with a single anionic resin but can optionally be carried out with several anionic resins.

The resins used for implementing the process according to the invention are preferably:

strong anionic resins, for example:

o DOWEX Monosphere: 550, 77, XUR1525, o AMBERLITE FPA 98, 90, 58, 42 o DIAION SA10, SA11, SA12, PA308, PA312, PA316, HPA25, UBA 100, UBA120 o PUROLITE PFAs o LANXESS S4268, S6368 o RESINEX CGA300 or weak anionic resins, for example:

o AMBERLITE CR5550, o AMBERLITE IRA 67, o DOWEX MONOSPHERE 66

Preferably, these are strong anionic resins.

Preferably, the method according to the invention is implemented with anionic resins having one or more of the following characteristics, preferably all: polystyrenic or polyacrylic having an average particle size of 150 to 950 μιτι,

- with a uniformity coefficient between 1.0 and 1.7.

The anionic resins used for implementing the process according to the invention are very preferably balanced with the majority anion of the solution, that is to say that the resin has been balanced so that the solution ions are present at the active sites of the resin in proportion to their concentration in the solution. In fact, the anionic ion exchange resin is thus not capable of carrying out an exchange between the ions in solution and the ions fixed on the matrix and very advantageously, the phenomenon of ion exchange which is can be observed with cationic resins which leads to a reduction in volume and a need for recharging during the process is thus made impossible, and the phenomenon of ion exclusion can be implemented.

According to a particularly suitable embodiment, the method according to the invention is implemented with at least one synthetic anionic resin with an anion having a selectivity for said resin greater than that of the most concentrated anion of the solution. Examples of selectivity values are given in the table below:

Strong anion selectivity HSiO ₃ “ <1.0 OH ^- (reference) 1 F 1.6 CH3COO- 3.2 H COO 4.6 io ₃ - 5.5 HCO3- 6 cr 22 NO ₂ - 24 BrO ₃ - 27 hso ₃ - 27 CN 28 HSOr 35 ΒΓ 50 # ₃ - 65 IOC ₃ - 74 SO4 ² - 150 r 175 SeO ₄ ² 280 CIO4- > 500 CrO ₄ ² - 1700 c ₆ h ₅ so ₃ - > 500

Advantageously, the method according to the invention, in comparison with the chromatographic method of excluding ions on cationic resin, allows:

to obtain a better yield, to improve the separation,

- to obtain better purity of the separate molecules, without having to recharge the resin with ions during the process.

The invention is particularly useful in industry for many applications. In particular, the subject of the invention is the use of the method described above for the separation of ionized molecules from non-ionized molecules in:

- candy molasses, to recover sucrose, biodiesel glycerol, to demineralize and discolor glycerol, whey and whey permeates, to demineralize lactose, organic juices, to separate ionized molecules from non-ionized molecules,

- solutions of salts and acids to separate salts from undissociated acids

The invention is now illustrated by test results and comparative tests.

TEST RESULTS AND COMPARATIVE TESTS DEMONSTRATING THE EFFECTIVENESS AND INTEREST OF THE INVENTION

1. Materials and methods

1.1 The process used for these tests is based on the principle of the simulated moving bed chromatographic process as defined by Yoritomi US4379751, example 4.

1.2 The chromatography device used comprises 6 or 8 columns of 98.5 cm * 2.66 cm in diameter (ie a volume of 547 ml of volume per column) connected in series. The temperature is maintained at 60 ° C.

The steps are in order:

o In parallel, the solution to be separated is injected into the first column of the third zone and the first part of the raffinate fraction (the salts resulting from the ion exclusion phenomenon) is recovered at the bottom of the last column of this same area; the eluent solution is injected into the First column of the first zone to recover the fraction of extract (non-ionized molecule retained by the resin) at the bottom of the last column of this same zone.

o The eluent solution is injected into the first column of the first zone and the second part of the raffinate fraction is recovered at the bottom of the last column of the third zone.

o All the columns are linked in a loop and a displacement volume is achieved.

At the end of these three stages, the injection and recovery points are moved simultaneously from one column downstream and the same sequence is repeated indefinitely until stationary operation is obtained.

1.3 The tests were carried out on 3 resins:

anionic resins (for implementing the method according to the invention), cationic resin (for implementing the method according to the prior art).

The resins are presented below:

Dowex marathon A Resinex CGA-300 Dowex 99/320 Exchange of anion anion cation functionality PSDVB-quaternary amine PSDVB- amine quaternary PSDVB- sulfonic acid Exchange capacity eq / l 1.3 1.35 1.5 Humidity % 50-60 49-55 57-61 Ball diameter pm 575 300 320 UC uniformity coefficient <1.1 <1.1 <1.1

Marathon A resin is a resin used mainly in the ion exchange process. It is not used in the chromatographic process because the average diameter of the beads of 575 μιτι does not promote rapid exchange with the medium.

The CGA-300 resin and the DOWEX99 / 320 resin are two chromatography resins, which can be confirmed by the small ball size at around 300 μιτι. With an identical resin volume, these resins have a contact surface twice that of the Marathon A, which promotes rapid exchanges.

1.4 The solutions tested are 2 model fluids which allow the process to be generalized to neighboring separations:

a synthetic solution comprising sodium chloride and glycerol; the separation therefore uses a monovalent mineral salt and a C3 polyol. The separation between a salt and a carbohydrate is comparable to those implemented for example in patents US2016325232 (A) and EP1978009 (A1) or for example US2013055903 (see FIG. 4a) which performs the separation between NaCl and propylene glycol.

a natural solution: beet molasses to recover the sucrose. This separation has been used for many years to recover the residual sugar from the sugar crystallization molasses, as demonstrated by patent DE2518284 dating from 1975 which implements an ion exclusion process with a strong cationic resin in potassium form.

2. Test results

Two different approaches have been implemented for adjusting the separations. It was sought to obtain an identical separation (similar purity and yield) in the case of

NaCI-glycerol and an identical setting was tested (identical productivity and consumption of eluent) in the case of molasses separation.

2.1. Separation of NaCl-glycerol.

columns were used for this separation.

During the stabilization of the separation with the cationic resin, it was necessary to reload the column of resins twice because a very strong irreversible settlement was noted, attributed to the effect of the osmotic pressure on the resin. The volume of resin in the column was measured after the tests at 570 ml on average while the columns have a theoretical volume of 547 ml. In addition, a reversible contraction of the column 10 has been observed when the solution is injected, which creates a dead volume at the top of the column reducing the chromatographic efficiency.

The resin returns to its initial volume during the passage into solvent (water). The anionic resin was charged at the start of the tests in chloride form. No irreversible or reversible settlement was observed. At the end of the tests, a resin volume of 545 ml was measured instead of the theoretical 547 ml.

The results obtained are presented in the table as follows:

SSMB process Dowex99 / 320 MARATHON A Food Glycerol g / l 244 NaCI g / l 216 Purity glycerol% 53 Glycerol fraction Glycerol g / l 233 283 NaCI g / l 1.3 2.0 Purity glycerol% 99.4 99.3 NaCI fraction Glycerol g / l 4.7 0.3 NaCI g / l 112 136 Purity glycerol% 3 0.1 Average eluent flow rate ml / min 16.3 16.3 Average raffinate flow rate ml / min 16.3 21.9 Average extract flow rate ml / min 8.7 10.3 Average feed rate ml / min 8.7 13.7 Glycerol yield% 96.3 99.8 Eluent volume / volume power 1.88 1.35 Productivity Kg / I.day 0.97 1.58

It can be seen that at practically identical separation performance, better productivity and lower consumption of eluent is obtained by using the Marathon A resin. It is possible to charge more the anionic resin than the cationic resin without reducing the quality of the separation.

This difference in behavior is linked to the better osmotic resistance of the anionic resin during the passage of the solution to be separated. Since there is no visible compaction of the resin, the dead volume is constant in all the columns and thus improves the separation.

2.2 Separation of beet molasses

This separation is carried out with a 6 column system.

During the stabilization of the separation with the cationic resin, it was necessary to reload the column of resins twice because a very strong irreversible settlement was noted, attributed to the effect of the osmotic pressure on the resin. The volume of resin in the column was measured after the tests at 570 ml on average while the columns have a theoretical volume of 547 ml. In addition, a reversible contraction of the column has been observed when the solution is injected, which creates a dead volume at the head of the column reducing the chromatographic efficiency. The resin returns to its initial volume during the passage into solvent (water).

The anionic resin was charged at the start of the tests in chloride form. No irreversible settlement or reversible settlement was observed. At the end of the tests, a volume of resin of 544 ml was measured instead of the theoretical 547 ml.

The results obtained are presented in the following table and in Figures 1 to 3:

SSMB process Dowex99 / 320 CGA 300 Food sugar g / l 244 Non-sugar g / l 216 Betaine g / l 53 Sugar purity% 60.7 Sugar fraction sugar g / l 306.5 372 Non-sugar g / l 23.5 2.8 Betaine g / l 15.0 10.4 Sugar purity% 86 93 NaCI fraction sugar g / l 16.4 9.3 Non-sugar g / l 50.5 55.7 Betaine g / l 5.5 7.8 Sugar purity% 18 11 Average eluent flow rate ml / min 14.39 14.39 Average raffinate flow rate ml / min 13.02 13.70 Average extract flow rate ml / min 4.80 4.11 Average feed rate ml / min 3.43 3.43 Sugar yield% 87 92 Eluent / feed volume 4.2 4.2 Productivity Kg / I.day 1.2 1.2

At identical setting, there is a very significant difference in separation between the 2 10 resins. The separation between the sugars and the non-sugars is better in the case of the anionic resin with a lower superposition of the separation curves: the ion exclusion effect is stronger in the case of the anionic resin.

The anionic resin makes it possible to obtain a less dispersed sugar peak, which promotes the sugar yield in the sugar fraction (Figure 1).

The anionic resin allows a better ion exclusion, the peak of non-sugars is more concentrated and less dispersed which allows to obtain a higher purity in the sugar fraction (Figure 2).

Betaine has a very different behavior between the anionic resin and the cationic resin. There is a significant accumulation in zone 2 which indicates that betaine is partially excluded from the anionic resin while it diffuses into the cationic resin to the point of being found mainly between zones 1 and 4 (Figure 3).

3. Conclusion on the tests

The test results obtained show that there is a very different dynamic behavior between anionic resins and cationic resins.

The resins were loaded in both cases in ionic balance with the solution. However, a very strong compression of the cationic resin bed is systematically observed during the injection of the feed solutions, which has resulted in the need to reload on each column twice: the observed settlement reaches 5%. column volume. The height of anionic resin initially charged remains constant during the period of reaching the steady state, and it is not necessary to reload the column unlike the cationic resin.

In addition, the very different behavior between the two types of resins means that the dead volume with the cationic resin due to compression due to the increase in osmotic pressure which appears during the process greatly degrades the quality of the separation. , while the anionic resin not varying in volume makes it possible to maintain a constant and better quality of separation than for the cationic resin with a better yield.

Claims (10)

1. Process for the separation of at least one ionized molecule from at least one non-ionized molecule, in a solution comprising at least one ionized molecule and at least one non-ionized molecule, characterized in that it is a continuous ion exclusion chromatography process implemented with at least one anionic resin. 2. Method according to claim, characterized in that the solution comprises at least one ionized molecule chosen from mineral salts, organic salts or a mixture. 3. Method according to one of the preceding claims, characterized in that it is a continuous ion exclusion chromatography process against the current of the simulated moving bed or sequenced simulated moving bed type or d '' a co-current continuous ion exclusion chromatography process. 4. Method according to one of the preceding claims, characterized in that the method is implemented with at least one strong anionic resin. 5. Method according to one of the preceding claims, characterized in that the method is implemented with at least one weak anionic resin. 6. Method according to one of the preceding claims, characterized in that the method is implemented with at least one anionic polystyrene or polyacrylic resin. 7. Method according to one of the preceding claims, characterized in that the method is implemented with at least one anionic resin having an average particle size of 150 to 950 pm and / or has a uniformity coefficient between 1.0 and 1.7 . 8. Method according to one of the preceding claims, characterized in that the method is implemented with at least one anionic resin which is a synthetic resin balanced with the most concentrated anion of the solution. 9. Method according to one of the preceding claims, characterized in that the method is implemented with at least one anionic resin which is a synthetic resin with an anion having a selectivity for said resin greater than that of the most anion solution concentrate. 10. Use of a process according to one of the preceding claims for the separation of ionized molecules from non-ionized molecules in sugar molasses, biodiesel glycerol, whey and whey permeates, organic juices, solutions of salts and acids.