Classifications

• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
  • B01D—SEPARATION
  • B01D67/00—Processes specially adapted for manufacturing semi-permeable membranes for separation processes or apparatus
  • B01D67/0081—After-treatment of organic or inorganic membranes
  • B01D67/0093—Chemical modification
  • B01D67/00931—Chemical modification by introduction of specific groups after membrane formation, e.g. by grafting
• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
  • B01D—SEPARATION
  • B01D67/00—Processes specially adapted for manufacturing semi-permeable membranes for separation processes or apparatus
  • B01D67/0081—After-treatment of organic or inorganic membranes
  • B01D67/0093—Chemical modification
• • C—CHEMISTRY; METALLURGY
  • C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
  • C08J—WORKING-UP; GENERAL PROCESSES OF COMPOUNDING; AFTER-TREATMENT NOT COVERED BY SUBCLASSES C08B, C08C, C08F, C08G or C08H
  • C08J5/00—Manufacture of articles or shaped materials containing macromolecular substances
  • C08J5/20—Manufacture of shaped structures of ion-exchange resins
  • C08J5/22—Films, membranes or diaphragms
  • C08J5/2206—Films, membranes or diaphragms based on organic and/or inorganic macromolecular compounds
  • C08J5/2218—Synthetic macromolecular compounds
  • C08J5/2231—Synthetic macromolecular compounds based on macromolecular compounds obtained by reactions involving unsaturated carbon-to-carbon bonds
  • C08J5/2243—Synthetic macromolecular compounds based on macromolecular compounds obtained by reactions involving unsaturated carbon-to-carbon bonds obtained by introduction of active groups capable of ion-exchange into compounds of the type C08J5/2231
• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
  • B01D—SEPARATION
  • B01D2323/00—Details relating to membrane preparation
  • B01D2323/38—Graft polymerization
• • C—CHEMISTRY; METALLURGY
  • C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
  • C08J—WORKING-UP; GENERAL PROCESSES OF COMPOUNDING; AFTER-TREATMENT NOT COVERED BY SUBCLASSES C08B, C08C, C08F, C08G or C08H
  • C08J2379/00—Characterised by the use of macromolecular compounds obtained by reactions forming in the main chain of the macromolecule a linkage containing nitrogen with or without oxygen, or carbon only, not provided for in groups C08J2361/00 - C08J2377/00
  • C08J2379/02—Polyamines

Definitions

• the present invention relates to the field of ionic membranes and, more particularly, to cation exchange membranes.
• the present invention provides a cation exchange membrane whose properties in terms of selectivity are improved, this improvement being due to a superficial modification of the membrane.
• the present invention also relates to a process for preparing such a cation exchange membrane and its various uses.
• the ion exchange membranes that are polymeric matrices allow the selective transfer of charged species according to their charge sign, cation transfer in the case of cation exchange membranes (CEMs), transfer of anions in the case of exchange membranes. of anxons (MEA) [1].
• Electrodialysis is an electromembrane technique in which the transfer of ions through a permeable ion exchange membrane takes place under the effect of an electric field.
• the essential property of a cation exchange membrane (CME) or anion (MEA) is the selective permeation of cations or anions through the membrane respectively. This anion / cation separation is also called "permselectivity".
• membrane with preferential selectivity or “specific cation exchange membrane (MECS)” has been developed.
• MECS specific cation exchange membrane
• the first method is to make a homopolar membrane (which contains only one type of ion exchange site) by adjusting the parameters such as the degree of crosslinking so that, in contact with a mixed solution which contains ions of different valence, the flow of monovalent cations and especially protons is greater than that of multivalent metal cations.
• the second method involves depositing a thin layer of anion exchange material on the surface of the cation exchange membrane to create positive charges that will act as an electrostatic barrier to the divalent cations and limit their penetration into the membrane. [5].
• the polymer film used is ethylenetetrafluoroethylene (ETFE) with a thickness of 100 ⁇ on which a chemical grafting of styrene has been carried out followed by a crosslinking with vinylbenzene (DVB).
• EFE ethylenetetrafluoroethylene
• DVB vinylbenzene
• the modification step is to effect amination on the surface of the chlorosulfonated membrane by means of a diamine (3-dimethylaminopropylamine) at room temperature; the -SO 2 CI groups thus form with the amine sulphonamide bonds (Scheme 1).
• the experimental difficulty lies in obtaining a very thin amine layer on the surface.
• This need is closely linked to an efficient process that allows, on the one hand, to modify the cation exchange membranes via a grafted layer to the latter and, on the other hand, to strictly control the thickness of the grafted layer.
• the present invention aims to provide a modified cation exchange membrane that meets the needs and technical problems mentioned above.
• the present invention relates to a cation exchange membrane consisting of a polymeric matrix and in particular a polymeric cation exchange matrix on the surface of which is grafted (e) at least one group of formula -R 1 - (CH 2 ) m -NR. 2 R 3 and / or at least one molecule bearing at least one group of formula -R 1 - (CH 2 ) m -NR 2 R 3 in which:
• R 1 represents an aryl group
• n 0, 1, 2 or 3;
• R 2 and R 3 which may be identical or different, represent a hydrogen or an alkyl group.
• the invention takes advantage of the ability of cation exchange membranes to be functionalized, ie to be modified at their surface by covalent grafting of chemical functions or polymer chains. It is this particular functionalization which guarantees the previously listed properties of the cation exchange membrane according to the invention, hereinafter referred to as "modified cation exchange membrane".
• the cation exchange membrane according to the invention consists of a polymeric matrix on the surface of which is grafted at least one group of formula -Ri - (CH 2 ) m -NR 2 R 3 , this group is linked to the cation exchange membrane implemented, in a covalent manner, by means of a bond involving an atom of the R 1 group (in particular an atom of a (hetero) aromatic ring present in the R 1 group) and an atom of the polymer matrix which constitutes this membrane.
• molecule bearing at least one group of formula -R 1 - (CH 2 ) m - R 2 R 3 is meant any natural or synthetic molecule, advantageously organic, comprising from a few atoms to several tens or even hundreds of atoms. This molecule can therefore be a chemical function, a single molecule or a molecule having a more complex structure such as a polymer structure.
• the molecule is linked to the cation exchange membrane implemented, covalently, by means of a bond involving an atom of said molecule and an atom of the polymeric matrix which constitutes this membrane, said molecule comprises therefore an atom (or a function) involved in the covalent bond with the surface of the polymeric matrix; on the other hand, the molecule comprises a group of formula -R 1 - (CH 2) m -NR 2 R 3.
• aryl group is meant, for defining the group R 1 according to the present invention, an aromatic or heteroaromatic carbon structure, optionally mono- or polysubstituted, consisting of one or more aromatic or heteroaromatic ring (s). ) each having 3 to 8 atoms, the heteroatom (s) may be N, 0, P or S.
• the substituent (s) may contain one or more heteroatoms such as N, O, F, Cl, P, Si, Br or S as well as alkyl groups.
• such a carbonaceous structure must carry at least one group of formula - (CH 2 ) r - R2R3 directly linked to one of its (hetero) aromatic rings.
• the group R 1 according to the present invention is an aromatic or heteroaromatic ring comprising 6 atoms, the heteroatom (s) possibly being N, O, P or S, bearing a group of formula - (CH 2 ) m -NR 2 R 3 directly bonded to a ring atoms and optionally substituted by one or more heteroatom (s) as (s) N, 0, F, Cl, P, Si, Br or s and alkyl groups.
• the group R 1 according to the present invention is a phenyl substituted at least by one group of formula - (CH 2 ) m -NR 2 R 3 directly linked to one of the phenyl atoms.
• the optional substituent (s) is a heteroatom such as N, O, F, Cl, P, Si, Br or S or an alkyl group.
• alkyl group is meant, for defining the groups R 2 and R 3 or the substituents of the group R 1 according to the present invention, an alkyl group, linear, cyclic or branched, optionally substituted, comprising from 1 to 6, in particular from 1 to 4 carbon atoms and optionally a heteroatom such as N, O, F, Cl, P, Si, Br or S.
• substituted alkyl is meant in the context of the present invention, an alkyl group substituted by a halogen, a methyl group, an ethyl group, an amino group or a diamine group.
• the group -NR 2 R 3 is a group capable, under the conditions of use of the cation exchange membrane according to the invention, to form a cationic group which brings a positive charge to the surface of the cation exchange membrane.
• These positively charged groups are intended to repel multivalent ions in a preferred manner over monovalent ions. Consequently, the group -NR 2 R 3 makes it possible to confer on the membrane grafted by a molecule bearing such a group a selectivity to the monovalent ions relative to the multivalent ions improved with respect to the selectivity of the virgin non-grafted membrane.
• the groups R 2 and R 3 which are identical or different, are chosen from the group consisting of hydrogen, methyl, ethyl or propyl. More particularly, the groups R 2 and R 3 are identical. Even more particularly, the groups R 2 and R 3 represent a hydrogen.
• the group of formula - (CH 2 ) m -NR 2 R 3 substituting the aryl group R 1 is, in particular, chosen from the group consisting of -NH 2 , -CH 2 -NH 2 and
• the group of formula - (CH 2) m -NR 2 R 3 substituent the aryl group R ⁇ is especially -NH 2.
• the -NH 2 groups give, under the conditions of use of the cation exchange membrane according to the invention, small - Hs + groups rather than large quaternary ammonium ions. In this case, the electrostatic fields decrease in inverse of the square of the distance (1 / r 2 ) and consequently are more intense if one approaches closer.
• the molecule grafted onto the surface of the cation exchange membrane according to the invention is a polymeric structure.
• this polymeric structure is a polymer or a copolymer mainly derived from several monomer units, identical or different, said polymer or copolymer bearing at least one group of formula -Ri (CH 2 ) m - R 2 R 3 as defined above.
• this polymeric structure is a (co) polymer mainly derived from several identical or different monomeric units bearing at least one group of formula -R 1 - (CH 2 ) m - R 2 R 3 as defined above. More particularly, this polymeric structure is a (co) polymer mainly derived from several identical or different monomeric units of formula -Ri [(CH 2 ) m -NR 2 R 3 ] - as defined above.
• the monomer units are linked to one another via the groups R 1 and advantageously via a covalent bond between two atoms, each carried by an aromatic ring of R 1 groups of two different monomers.
• the cation exchange membrane according to the invention is grafted with a group of formula -Ri (CH 2 ) m -NR 2 R 3 and / or by a molecule bearing at least one such group, in particular in the form of a polymeric structure , the thickness of the grafting ie the thickness of the layer thus grafted is less than 100 nm, advantageously less than 80 nm, especially less than 60 nm and, in particular, between
• polymeric matrix is meant the base portion of the cation exchange membrane which gives shape to the latter and the cation exchange character. Any polymer matrix commonly used for a cation exchange membrane can be used in the context of the present invention.
• the polymer matrix used can be a commercial polymeric matrix such as a Selemion CMV membrane matrix (Asahi Glass, Japan), Neosepta CMX membrane (Tokuyama Soda, Japan) or a CMI-7000S matrix (Membrane International Inc., USA) .
• This polymeric matrix has ionic groups, identical or different, capable of conferring its permselectivity. These ionic groups are in particular chosen from -SO 3 -, - ⁇ O 3 2- , -HPO 2 -, -COO-, -Se0 3 2- and -AsO 3 2- .
• this polymeric matrix has a thickness of between 1 ⁇ and 1 cm, in particular between 2 ⁇ m and 500 ⁇ m and, in particular, between 5 ⁇ m and 150 ⁇ m.
• this technique can be a chemical method during which a polymer comprising aromatic rings is functionalized by ionic groups as defined above or by groups comprising one or more ionic groups as defined above.
• a polymer comprising aromatic rings may be, by way of non-limiting examples, polyaryletheretherketone (PEEK), styrene-divinylbenzene, styrene-butadiene, styrene-isoprene-styrene or styrene-ethylene / butylene-styrene.
• PEEK polyaryletheretherketone
• styrene-divinylbenzene styrene-butadiene
• styrene-isoprene-styrene or styrene-ethylene / butylene-styrene.
• this technique may involve a radiochemical step followed by a chemical step in accordance with the chemical method as previously described.
• the radiochemical step is to graft, under the influence of gamma radiation, X or electron, an aromatic compound on an inert polymer.
• An aromatic compound which may be used is in particular a polymer comprising aromatic rings, as defined above.
• An inert polymer may be, by way of non-limiting examples, a polyurethane, a polyolefin, a polyethylene terephthalate, a polycarbonate, polyethylene, a fluorinated polymer such as polyvinylidene fluoride or polytetrafluoroethylene, a polyamide or polyacrylonitrile.
• the polymer matrix that can be used in the context of the present invention can be nanostructured and in particular comprise, in its thickness, substantially cylindrical zones, such as channels, which advantageously join two opposite faces of the matrix.
• This nanostructuration can increase the selectivity already obtained with the grafting object of the present invention.
• these substantially cylindrical zones make it possible to promote the passage of cations having a small diameter unlike cations with larger diameters.
• These substantially cylindrical zones passing through the polymeric matrix comprise chains polymers covalently bound to the constituent polymer of the matrix and chosen from:
• the polymer chains comprising a main chain, at least a part of which of which is bonded to both a -COOR group and a -SO 3 R or -PO 3 R 2 group , R representing a hydrogen or a halogen, an alkyl group or a cationic counterion;
• polymeric chains comprising a main chain comprising pendant phenyl groups, at least some of which groups comprise at least one hydrogen atom substituted with a -SO 3 R or -PO 3 R 2 group , R having the same meaning as that given above, and
• These substantially cylindrical zones can pass through the thickness of the polymeric matrix at variable or identical angles. They can have a diameter ranging from 10 to 100 nm (nanozones). These zones may also be hollow, in which case the grafts are bonded to the wall of said zones.
• the polymeric matrix may comprise from 5.10 4 to 5.10 10 , preferably from 10 5 to 5.10 9 zones per cm 2 .
• Such a nanostructured polymer matrix has 1) a large ion exchange capacity; 2) a capacity to provide proton conduction at working temperatures above 80 ° C, for example 120 ° C; 3) resistance to pressures of 10 bars; 4) inertia with respect to corrosion phenomena.
• a nanostructured polymeric matrix is advantageously a matrix made of an inert polymer as defined above, in particular a matrix ( made of a fluorinated inert polymer and, in particular, PVDF.
• the polymeric chains bound to the constituent polymer of the polymeric matrix can be in various forms.
• the polymer chains comprise a main chain, of which at least a portion of the carbon atoms is bonded to both a -COOR group and a -SO 3 R or -PO 3 R 2 group.
• a main chain of which at least a portion of the carbon atoms is bonded to both a -COOR group and a -SO 3 R or -PO 3 R 2 group.
• Such polymer chains may result from the polymerization of acrylic monomers having at least one -CO 2 R group, such as acrylic acid, the resulting polymers having undergone a sulfonation or phosphanation step to introduce the -SO 3 R groups or - PO3R 2 on at least a portion of the atoms bearing -CO2R groups, R being as defined above.
• the polymeric grafts comprise a main chain comprising pendant phenyl groups, at least a part of which groups comprises at least one hydrogen atom substituted with a -SO3R or -PO3R2 group, R being as defined above.
• Such polymer chains may result from the polymerization of monomers comprising aromatic rings followed by a sulfonation or phosphanation step so as to introduce on at least one of the carbon atoms of the phenyl groups a group - SO 3 R or -PO 3 R 2 , R being as defined above.
• the polymer chains obtained following the polymerization step are polymers comprising aromatic rings as previously defined.
• the preparation method of the invention may comprise the following steps:
• the irradiation step (i) of a polymeric matrix may consist in subjecting said matrix to bombardment with heavy ions, especially chosen from krypton, lead and xenon.
• this step may consist in bombarding the polymer matrix with a heavy ion beam, such as a 4.5 MeV / mau Pb ion beam or a 10 MeV Kr ion beam. / fc.
• a heavy ion beam such as a 4.5 MeV / mau Pb ion beam or a 10 MeV Kr ion beam. / fc.
• the heavy energy vector ion passes through the matrix, its speed decreases.
• the ion gives up its energy, creating damaged areas, whose shape is approximately cylindrical.
• These areas are called “latent traces” and include two regions: the heart and the halo of the trace.
• the core of the trace is a totally degraded zone, namely an area where there is rupture of the constituent bonds of the material generating free radicals.
• This core is also the region where the heavy ion transmits a considerable amount of energy to the electrons of the material. Then, from this heart, there is emission of secondary electrons, which will cause defects far from the heart, thus generating a halo.
• the irradiation step may also be carried out by UV irradiation or electron irradiation, provided however that a mask defining the substantially cylindrical zones to be created by the irradiation is used.
• the method for preparing a nanostructured polymeric matrix may comprise, after the irradiation step, a step of revealing (ii) latent traces created by the irradiation step.
• the chemical revelation may consist in bringing the matrix into contact with a reagent able to hydrolyze the latent traces, so as to form hollow channels instead of these.
• the latent traces generated have short chains of polymers formed by splitting existing chains during the passage of the ion in the material during the irradiation.
• the rate of hydrolysis during the revelation is greater than that of the non-irradiated parts.
• the reagents capable of revealing the latent traces are a function of the material constituting the matrix.
• the latent traces can in particular be treated with a strongly basic and oxidizing solution, such as a KOH ION solution in the presence of KMnC> 4 at 0.25% by weight at a temperature of 65 ° C., when the polymeric matrix is, for example made of a fluoropolymer.
• a strongly basic and oxidizing solution such as a KOH ION solution in the presence of KMnC> 4 at 0.25% by weight at a temperature of 65 ° C.
• Treatment with a basic solution optionally coupled with trace sensitization by UV, may be sufficient for example for polymers such as polyethylene terephthalate (PET) and polycarbonate (PC).
• PET polyethylene terephthalate
• PC polycarbonate
• the treatment leads to the formation of cylindrical pores hollow whose diameter is adjustable as a function of the attack time with the basic and oxidizing solution.
• heavy ion irradiation will be carried out so that the membrane has a number of traces per cm 2 between 10 6 and 10
• the process for preparing a nanostructured polymeric matrix then comprises a grafting step (iii) of bringing the irradiated and optionally exposed matrix into contact with an ethylenic monomer.
• the grafting step of the ethylenic monomer is likely to take place in three phases:
• reaction phase of the ethylenic monomer at the aforementioned zones this initiation phase being materialized by an opening of the double bond by reaction with a radical center of the matrix, the radical center thus "moving" from the matrix to a a carbon atom derived from said ethylenic monomer;
• the free radicals present within the aforementioned zones cause the propagation of the polymerization reaction of the ethylenic monomer contacted with the matrix.
• the radical reaction is thus, in this case, a radical polymerization reaction of the ethylenic monomer brought into contact, from the irradiated matrix.
• the membranes obtained will thus comprise a polymer matrix grafted with polymers comprising repeating units resulting from the polymerization of the ethylenic monomer brought into contact with the irradiated matrix.
• the method of the invention finally comprises a sulfonation or phosphanation step (step iv).
• the sulphonation step consists of introducing a sulphonic group -SO 3 R into a molecule by carbon-sulfur direct bond, the sulphonation possibly taking place by a direct sulphonation reaction (addition reaction), an atom substitution reaction. of halogen or a diazo group by a sulfonic group, an oxidation reaction of a sulfide group.
• This sulfonation step may consist in treating the grafted matrix with a chlorosulfonic acid solution.
• the phosphanation step consists in introducing a phosphonium group -PO 3 R 2 into a molecule, by direct carbon-phosphorus bonding.
• a step can be carried out by a Michaelis-Arbuzov or Michaelis-Becker reaction on a molecule carrying a halogen atom, thus leading to the formation of phosphonic acid ester, followed by a possible hydrolysis to allow obtaining the corresponding phosphonic acid.
• a step can be carried out by a Friedel-Craft reaction followed by a possible hydrolysis leading to the corresponding phosphonic acid.
• the present invention also relates to the use of a modified cation exchange membrane according to the present invention. Indeed, the latter by the presence of a layer grafted on its surface, layer bearing groups of formula -Ri - (CH 2 ) m -NR 2 R 3 capable of forming cationic groups that repel multivalent cations and in particular Bivalents such as Ni 2+ , Ca 2+ , Pb 2+ , Cu 2+ , Ti 2+ or Zn + are selectively permeable to monovalent cations and in particular to alkaline cations.
• monovalent optionally alkaline cations mention may be made of H + , Na + , K + and Li + .
• the grafting of a layer carrying groups of formula -Ri - (CH 2 ) m -NR 2 R 3 on the surface of the cation exchange membrane according to the invention makes it possible to increase the mobility ratio X + / Y n + with X + , Y n + and n a monovalent cation, a multivalent cation and an integer greater than or equal to 2, respectively; notably the X + / Y + mobility ratio and, in particular, the H + / Ni + mobility ratio.
• This increase may be of a factor greater than 2, greater than 3, greater than 4 or even greater than 5 relative to the corresponding mobility ratio, obtained for the cation exchange membrane which has not undergone a modification according to the present invention ie a virgin membrane.
• the grafting of a layer carrying groups of formula -R 1 - (CH 2 ) m - NR 2 R 3 does not modify the ion exchange capacity of the modified membrane relative to the virgin membrane.
• the cation exchange membrane according to the present invention is useful for the electrodialysis of a solution [1].
• This solution is advantageously chosen from the group consisting of brackish water, spring water, drinking water, seawater, an industrial effluent, a solution from the food industry or a solution. from the fine chemical industry or the pharmaceutical industry.
• the cation exchange membrane according to the present invention can be used not only to produce drinking water from brackish water or seawater, but also to eliminate any metal cation type contaminants or reduce the load in drinking water or spring water.
• the cation exchange membrane according to the present invention can be used for the treatment of industrial effluents by electrodialysis, and in particular to remove any toxic heavy metals they may contain.
• These industrial effluents can come from the industry pulp mill, the hydrometallurgical industry, the surface treatment industry or the tanning industry.
• electrodialysis involving a cation exchange membrane according to the present invention can be used to demineralize whey; to deacidify and / or demineralize fruit juices and sugar solutions; to produce organic acids.
• a cation exchange membrane according to the present invention can be used to purify active pharmaceutical ingredients or amino acids; to prepare isotonic solutions; to produce organic acids; to concentrate acids.
• the present invention also relates to a method for preparing a cation exchange membrane as defined above.
• the process of the present invention consists in grafting onto a polymeric matrix as described above at least one group of formula -R 1 - (CH 2 ) -NR 2 R 3 and / or at least one molecule bearing at least one such group.
• grafting technique Any grafting technique known to those skilled in the art can be used in the context of the present invention. However, a technique advantageously implemented is that described in the international application WO 2008/078052 [16], this technique involving radical chemical grafting.
• the term "radical chemical grafting” refers in particular to the use of molecular entities having an unpaired electron to form covalent link bonds with the surface of the polymeric matrix of the membrane, said molecular entities being generated independently of the surface on which they are intended to be grafted.
• radical chemical grafting as described in [16] allows a covalent grafting in a single step, adding material to the polymer matrix and not modifying it.
• radical chemical grafting as described in [16] is controlled and controllable in thickness which makes it possible to avoid a decrease in the resistance and / or the production of bipolar membrane effect.
• radical chemical grafting involves radical, highly reactive species that bind to the surface of the matrix before having been able to penetrate the thickness of the latter, there are no disturbances of the volume properties and therefore of the electrical resistance of the polymeric matrix.
• radical species generated during radical chemical grafting can react with a any reactive group of the polymeric matrix which allows to have a large population of sites on which the grafting can take place and thus obtain a high charge density.
• 3-dimethylaminopropylamine reacts only with the chlorosulfonated groups which themselves depend on the initial population of styrene groups themselves depending on the initial degree of grafting.
• the radical species generated during radical chemical grafting can bind to both the chlorosulfonated styrene groups, the non-chlorosulfonated styrene groups and any other reactive group. present on the surface of the membrane.
• reactive group is meant a group capable of reacting with a radical center.
• the process for preparing a cation exchange membrane according to the present invention advantageously consists in reacting on the polymer matrix as defined above, by free radical chemical grafting, a cleavable aryl salt carrying at least one group of formula - (CH) 2 ) ra - R 2 R 3 with m, R 2 and R 3 as previously defined, directly linked to a (hetero) aromatic ring.
• the cleavable aryl salt employed selected from the group consisting of aryl diazonium salts, aryl ammonium salts, aryl phosphonium salts and aryl sulfonium salts, said aryl group having at least one group of formula - (CH 2 ) m -NR 2 R 3 with m, R 2 and R 3 as previously defined, directly linked to a (hetero) aromatic ring.
• the aryl group is an aryl group which may be represented by R 1 as previously defined.
• A represents a monovalent anion
• R 1, R 2 and R 3 are as previously defined.
• A may especially be chosen from inorganic anions such as halides such as I “ , Br ⁇ and Cl " , haloborates such as tetrafluoroborate, perchlorates and sulfonates and organic anions such as alcoholates and carboxylates.
• inorganic anions such as halides such as I “ , Br ⁇ and Cl "
• haloborates such as tetrafluoroborate, perchlorates and sulfonates
• organic anions such as alcoholates and carboxylates.
• this grafting step consists in subjecting, optionally in the presence of at least one polymeric matrix as defined above, a solution S containing at least one cleavable aryl salt bearing at least one group of formula - (CH 2 ) m -NR 2 R 3 with m, R 2 and R 3 as defined above, directly linked to a (hetero) aromatic ring or a precursor of such a cleavable aryl salt, under conditions allowing the formation of at least one radical entity from said cleavable aryl salt or said precursor.
• cleavable aryl salt bearing at least one group of formula - (CH 2 ) m -NR 2 R 3 directly linked to a (hetero) aromatic ring is meant in the context of the present invention a molecule separated from said cleavable aryl salt by a single process step which is easy to carry out.
• arylamines are precursors of aryl diazonium salts. Indeed, by simple reaction, for example, with NaNO 2 in an acidic aqueous medium, or with NOBF 4 in an organic medium, it is possible to form the corresponding aryl diazonium salts.
• a precursor advantageously used in the context of the present invention is a precursor of aryl diazonium salts of formula (II) below:
• R 1, R 2 , R 3 and m being as previously defined.
• a precursor that may be used in the context of the present invention is 4-aminophenylamine (or p-phenylenediamine) or 4-aminomethylphenylamine.
• Solution S implemented in the grafting step of the process according to the present invention contains, as a solvent, a solvent which can be:
• a protic solvent ie a solvent which comprises at least one hydrogen atom capable of being released in the form of a proton and advantageously chosen from the group consisting of water, deionized water, distilled water, acidified or basic, acetic acid, hydroxylated solvents such as methanol and ethanol, low molecular weight liquid glycols such as ethylene glycol, and mixtures thereof;
• an aprotic solvent ie a solvent which is not capable of releasing a proton or of accepting a proton under non-extreme conditions and advantageously chosen from dimethylformamide (DMF), acetone, acetonitrile and dimethyl sulfoxide (DMSO);
• the conditions allowing the formation of at least one radical entity in the grafting step of the process of the present invention are conditions which allow the formation of radical entities in the absence of the application of any electrical voltage to the reactor.
• reaction mixture comprising a solvent, at least one polymer matrix, at least one cleavable aryl salt bearing at least one group of formula - (CH 2 ) m -NR 2 3 directly linked to a (hetero) aromatic ring or a precursor of such a cleavable aryl salt.
• These conditions involve parameters such as, for example, the temperature, the nature of the solvent, the presence of a particular additive, stirring, pressure while the electric current does not occur during the formation of radical entities.
• the conditions allowing the formation of radical entities are numerous and this type of reaction is known and studied in detail in the prior art.
• a cleavable aryl salt bearing at least one group of formula - (CH 2 ) m --NR. 2 R 3 directly linked to a (hetero) aromatic ring or a precursor of such a salt in order to destabilize it so that it forms a radical entity. It is of course possible to act simultaneously on several of these parameters.
• the conditions allowing the formation of radical entities during the grafting step according to the invention are typically chosen from the group consisting of the thermal conditions, the kinetic conditions, the chemical conditions, the conditions photochemical conditions, radiochemical conditions and their combinations to which the molecule or its precursor is subjected.
• the conditions used in the context of the grafting step of the process according to the present invention are chosen from the group consisting of thermal conditions, chemical conditions, photochemical conditions, radiochemical conditions and their combinations. between them and / or with the kinetic conditions.
• the conditions used in the context of the grafting step of the process according to the present invention are more particularly chemical conditions.
• the thermal environment is a function of the temperature. Its control is easy with the heating means usually employed by those skilled in the art. The use of a thermostated environment is of particular interest since it allows precise control of the reaction conditions.
• the kinetic environment essentially corresponds to the agitation of the system and the friction forces. It is not a question here of the agitation of the molecules in itself (elongation of bonds, etc.), but of the global movement of the molecules.
• solution S is subjected to mechanical stirring and / or ultrasonic treatment.
• the solution S implemented during the grafting step is subjected to a high speed of rotation by means of a magnetic stirrer and a magnetic bar and this, for a period of time of between 5 minutes. and 24 h stirring, especially between 10 min and 12 h and, in particular, between 15 min and 6 h.
• the solution S used during the grafting step is subjected to ultrasonic treatment, in particular by using an ultrasound tank, typically with an absorption power of 500 W and at a frequency of 25 or 45 kHz and this, for a period of between 1 min and 24 h agitation, including between 15 minutes and 12 hours, and in particular between 30 minutes and 6 hours.
• the action of various radiations such as electromagnetic radiation, ⁇ rays, UV rays, electron or ion beams can also sufficiently destabilize the cleavable aryl salt bearing at least one group of formula - (CH 2 ) m -NR 2 R 3 directly linked to a cycle
• the solution S is used in the reaction medium one or more chemical initiator (s).
• chemical initiators is often coupled with non-chemical environmental conditions, as discussed above.
• a chemical initiator whose stability is less than that of the cleavable aryl salt or the precursor used under the selected environmental conditions will evolve in an unstable form which will act on them and generate, from them, the formation of radical entities.
• chemical initiators whose action is not essentially related to environmental conditions and which can act over wide ranges of thermal or kinetic conditions.
• the initiator will preferably be adapted to the environment of the reaction, for example to the solvent employed.
• chemical initiators There are many chemical initiators. There are generally three types depending on the environmental conditions used:
• thermal initiators the most common of which are peroxides or azo compounds. Under the action of heat, these compounds dissociate into free radicals. In this case, the reaction is carried out at a minimum temperature corresponding to that required for the formation of radicals from the initiator.
• This type of chemical initiator is generally used specifically in a certain temperature range, depending on their kinetics of decomposition;
• the photochemical or radiochemical initiators which are excited by radiation triggered by irradiation (most often by UV, but also by ⁇ radiation or by electron beams) allow the production of radicals by more or less complex mechanisms.
• Bu 3 SnH and I 2 belong to photochemical or radiochemical initiators;
• initiators essentially chemical initiators, this type of initiators acting rapidly and under normal conditions of temperature and pressure on the molecule or its precursor to enable it to form radicals.
• Such initiators generally have a redox potential which is lower than the reduction potential of the cleavable aryl salt or precursor used in the reaction conditions.
• the cleavable aryl salt or its precursor it may thus be for example a reducing metal, such as iron, zinc, nickel; a metallocene; an organic reducing agent such as hypophosphorous acid (H3PO 2 ) or ascorbic acid; of an organic or inorganic base in proportions sufficient to allow destabilization of the cleavable aryl salt or its precursor.
• the reducing metal used as chemical initiator is in finely divided form, such as wool (also called more commonly "straw") metal or metal filings.
• wool also called more commonly "straw" metal or metal filings.
• a pH of greater than or equal to 4 is generally sufficient.
• Radical reservoir-type structures such as polymer matrices previously irradiated with an electron beam or by a heavy ion beam and / or by all the irradiation means mentioned above, can also be used as chemical initiators for destabilizing the cleavable aryl salt or its precursor and leading to the formation of radical entities from this salt.
• the method according to the invention comprises the following steps:
• step (b) putting the polymeric matrix as defined above in contact with the radical entity obtained in step (b) present in said solution S whereby grafting of a group of formula -Ri (CH2) is obtained; m - R 2 R 3 and / or a polymeric structure carrying at least one such group on said polymeric matrix,
• Scheme 2 shows the steps of such a process using, as a precursor, p-phenylenediamine.
• the amount of cleavable aryl salt or precursor of this cleavable aryl salt in solution S may vary depending on the experimenter's desire. This quantity is advantageously included, within the solution S, between 10 ⁇ 6 and 5 M approximately, preferably between 5.1CT 2 and 1 TCT 1 M.
• Step (c) of the process according to the present invention corresponds to the grafting step as defined above. It can last from 10 minutes to 6 hours, in particular from 30 minutes to 4 hours, in particular from 1 to 2 hours, and more particularly approximately 90 minutes ( ⁇ 10 minutes).
• the grafting step can to be stopped before all the molecules are fixed on the carbon nanotubes.
• Those skilled in the art know different techniques to stop the grafting step and will determine the most suitable technique depending on the cleavable aryl salt or its precursor implemented. By way of examples of such techniques, mention may be made of a change in pH of the solution S, in particular by adding a basic solution (for example, basic water at a pH greater than 10), an elimination of the salt of cleavable aryl in solution S (for example, by filtration, precipitation or complexation) or removal of the polymeric matrix from solution S.
• a basic solution for example, basic water at a pH greater than 10
• an elimination of the salt of cleavable aryl in solution S for example, by filtration, precipitation or complexation
• FIG. 1 is a schematic representation of the mercury cell useful for measuring membrane resistance.
• Figure 2 shows scanning electron microscopy (SEM) images of the surface ( Figures 2A and 2B) and the section ( Figures 2C and 2D) of the blank ( Figures 2A and 2C) and modified ( Figures 2B and 2D) membranes. .
• Figure 3 shows the Infra-Red spectra of the virgin CMV membrane (curve (a)) and the CMV membrane modified with a thin layer of polyaniline type (curve (b)).
• Figure 4 shows the X-ray photoelectron spectrometry (XPS) spectra of the virgin CMV membrane (curve (a)) and the CMV membrane modified by a thin layer of polyaniline type (curve (b)).
• XPS X-ray photoelectron spectrometry
• FIG. 5 shows the X-ray photoelectron spectrometry (XPS) spectra of the virgin PVDF membrane (FIG. 5A), the PAA-modified PVDF membrane (FIG. 5B) and modified by a thin polyaniline-type layer (FIG. 5C).
• XPS X-ray photoelectron spectrometry
• Figure 6 shows the impedance diagram recorded on the virgin CMV membrane (triangles) and CMV membrane modified by a thin layer of polyaniline type (squares).
• Figure 7 shows the equivalent fraction of nickel ions in the modified membrane as a function of the nickel equivalent concentration in the equilibration solution (curve a) and the conductivity of the modified membrane (curve b).
• Figure 8 shows the variation of the conductivity of the membrane as a function of the equivalent fraction of nickel ions in the modified membrane.
• the radiografting rate was calculated by the following ratio: where W f and Wi represent the weight of the membrane after and before grafting of the vinyl monomer. The radiografting rate was determined at 140% by mass. The membrane was analyzed by Fourier transform infrared spectrometry in ATR mode. The specific vibration bands of polystyrene at 2985 cm -1 and at 3025 cm -1 have been observed 1.2.3 Acrylic acid radiografting protocol.
• a membrane irradiated with heavy ions (point 1.2.1) is immersed in a solution of acrylic acid, water (60/40) and 0.1% by weight of Mohr salt in a radiografting tube and then bubbling in. the nitrogen is carried out for 15 minutes. Mohr salt has been used to limit the homopolymerization of acrylic acid.
• the tube is then sealed and placed in a bath at 60 ° C for 1 h.
• the membrane obtained was then extracted from the solution and then washed with water and extracted with boiling water using a Sohxlet apparatus for 24 hours. It was then dried for 12 hours under high vacuum.
• the radiografting rate was calculated by the following ratio: where W f and Wi represent the weight of the membrane after and before grafting of the vinyl monomer. The radiografting rate was determined at 50% by mass. The membrane was analyzed by Fourier transform infrared spectrometry in ATR mode. The specific vibration band of poly (acrylic acid) at 1703 cm -1 was observed.
• the PVDF-g-PS membrane was immersed in a solution of dichloromethane for 20 min at room temperature so that the membrane was swollen. The membrane is then immersed in a solution of 10% chlorosulfonic acid in dichloromethane at room temperature for 30 min. The membrane is then rinsed twice with dichloromethane (2 ⁇ 50 mL) and then dipped in 1 M sodium hydroxide solution at room temperature for 2 hours. In order to reacidify the membrane, it is rinsed twice in deionized water (2 x 100 mL) and then dipped in a 1 M sulfuric acid solution at room temperature for 3 h.
• the resulting membrane was dried under vacuum at 50 ° C for 12 h.
• the membrane was analyzed by Fourier transform infrared spectrometry in ATR mode. The specific vibration band of the SO 3 group at 1029 cm -1 was observed.
• the PVDF-g-PAA membrane was immersed in a solution of 100% chlorosulfonic acid at room temperature for 6 hours. The membrane is then rinsed twice with dichloromethane (2 x 50 mL) in tetrahydrofuran (2 x 50 mL) in ethanol
• the membranes were immersed in a 1M NaCl solution for 24 h at room temperature.
• the solution was titrated with 0.01 M sodium hydroxide solution using phenolphthalein as a color indicator.
• the IEC of the PVDF-g-PS-S0 3 H membrane was evaluated at 2.97 rnq.g -1 of proton exchange functions.
• the IEC for the PVDF-g-PAA- 3 H membrane was evaluated at 3 meq.g -1 " of proton exchange functions.
• a hydrochloric acid solution of pH 0.3 (HCl). , 5 M).
• 5 ml of a solution of 0.1 M sodium nitrite is added dropwise into the same volume of a p-phenylenediamine solution.
• 0.5 g of iron filings is added to create the salt reduction reaction.
• the solution creates a foam of nitrogen bubbles (from the reduction of dxazonium salt) and hydrogen (due to the attack of iron filings in the acid medium).
• the membrane (33 cm) is introduced.
• the SEM images were recorded on a Hitachi S4500 Field Emission Gun (SEM).
• IR spectra were recorded on a Vertex 70 Bruker spectrometer with an ATR Pike-Miracle accessory.
• the detector is a MCT cooled with liquid nitrogen.
• the spectra were acquired with 256 scans with a resolution of 2 cm -1, XPS recordings were made on a KRATOS Axis Ultra DLD with an Alkoc source at 1486, 6 eV, and the pass energy was set at 20 eV heart levels III.2 Ion exchange capacity.
• Membrane samples of known weight are converted to the Na + form by stirring in a 1 M NaCl solution.
• the membranes are then washed and equilibrated for absorption in a 1.0 M HCl solution for 24 h to 25 min. ° C. They are rinsed again with distilled water to completely disgorge the sorbed HC1 and finally placed in a 1M NaCl solution to obtain the exchange reaction between the H + ions bonded to the sulfonate sites and the Na + ions in the solution.
• External NaCl External NaCl.
• the amount of protons in the solution obtained is estimated by acid-base titration (DMP Titrino Metrohm) and the ion exchange capacity C ex is expressed as an amount of H + ions (mmols) per gram of dry membrane.
• the electrodialysis cell is composed of two compartments.
• the membrane is placed in a circular orifice between the two compartments.
• the seal is made by flat joints circular.
• the apparent area of the membrane is 6 cm 2 .
• Two plates of platinum titanium are used as anode and cathode and placed at the ends of the two compartments.
• the anode compartment contains 250 ml of a solution composed of 0.25 M NiSO 4 and 0.25 M H 2 SO 4.
• the cathode compartment contains 25 ml of a solution containing only 0.5 M H 2 SO 4.
• a current of 60 mA is applied through the cell for 30 min with a 1286 Solartron potentiostat controlled by the Corrware software.
• the quantities of nickel and protons are controlled by atomic absorption spectroscopy and a titrator (DMP Titrino Metrohm). III.4. Isothermic ion exchange.
• the membranes are first immersed for 24 h in a 0.5 M H 2 SO 4 solution. After drying the surface-deposited sulfuric acid with absorbent paper, the membranes are immersed for 24 h with stirring in an N1SO solution. 4 x N and 0.5 N H 2 SO 4 (with x being 0.05, 0.1, 0.2 and 0.5) to charge ions to equilibrium. The membranes are then removed from the solution, buffered with absorbent paper, and then immersed again in 1M NaCl solution for 24 hours in order to exchange and disgorge all the hydrogen and nickel ions. The quantities of nickel released in solution are determined by atomic absorption spectroscopy. III.5. Membrane resistance.
• the electrical resistance values of the equilibrated membranes in given solutions are measured by electrochemical impedance spectroscopy (EIS) using the mercury cell (FIG. 1). To collect this information, platinum wires are immersed in mercury in direct contact with the membrane and thus constitute the measuring electrodes. The effective contact of the membrane with the mercury area is 0.866 cm 2.
• the electrical resistance values of the balanced membranes in given solutions of sulfuric acid are measured by electrochemical impedance spectroscopy (EIS).
• EIS electrochemical impedance spectroscopy
• the cell composed of two compartments is conditioned with an equivalent volume of mercury to bring into contact the entire surface of the membrane.
• the electrical contacts with mercury are taken by platinum / palladium wires.
• An alternating current of variable frequency is used to make the analysis by SIE.
• An impedance diagram defined between frequencies of 1 Hz to 100 kHz makes it possible to define the resistance in the high frequency part. Measurements are made by a set 1286 (potentiostat) -1255 (frequency analyzer) from Solartron driven by Zview software.
• Figure 2 Chemical mechanisms leading to the grafting of aromatic amine functions on membrane surfaces.
• the membrane at the end of the reaction is first rinsed with 0.5M hydrochloric acid to remove any trace of iron particles. It is then packaged in a 1M NaCl solution to exchange sodium protons in the volume of the membrane. Finally, the membrane is rinsed with deionized water. It should be noted that at this stage the surface amine groups are neutralized. They will become charged groups intended to repel the multivalent ions when they are in the conditions of use ie in acid medium for which the pHs are sufficient to manufacture the conjugated acid form of the amino base.
• the pka of aniline is 4.63 c.a.d that the usual pH of acid effluents will always be lower than this value.
• Figure 3 shows the IR spectra before and after modification.
• the bands associated with the groups -SO 3 - are still visible even though they have slightly decreased in intensity.
• New bands at 1510 and 1610 cm -1 and also at 3350 cm -1 are respectively attributed to NH 2 deformation and elongation NH vibrations.
• the general appearance of the spectrum corresponds to the presence of the membrane and a thin layer of polyaniline type as can be observed on a metal surface.
• the IR analysis is made, taking into account the ATR method, over a thickness of 1 to 3 ⁇ m with respect to the surface of the membrane.
• the virgin and modified membranes are also analyzed by XPS. This time the surface analysis is done at the nanometer scale (10-20 nm).
• the CMV membrane virgin shows peaks at 1072 eV (Na ls), 977 eV (0 KLL Auger peak), 532 eV (0 ls), 497 eV (Na KLL Auger peak), 228 eV (S 2s) and 169 eV (S 2p) characteristics of sulphonate groups as well as peaks at 271 eV (Cl 2s), 200 eV (Cl 2p) and 285 eV (Cls) attributed to the polyvinyl chloride (PVC) backbone [12, 18].
• PVC polyvinyl chloride
• the stability of the grafted layer is demonstrated by the fact that the spectra shown above are systematically obtained after a long ultrasound pass. Some samples even remained for one week in 0.5M hydrochloric acid.
• the grafting of the polyaniline type layer on the PVDF-g-PAA membrane is carried out according to the procedure described in point II and described in section IV.1.
• the membrane at the end of the reaction is first rinsed with 0.5M hydrochloric acid to remove any trace of iron particles. It is then packaged in a 1M NaCl solution to exchange sodium protons in the volume of the membrane. Finally, the membrane is rinsed with deionized water. It should be noted that at this stage the surface amine groups are neutralized. They will become charged groups destined to repel multivalent ions when they are in use conditions i.e. in acidic medium for which the pHs are sufficient to manufacture the conjugated acid form of the amino base.
• the pka of aniline is 4.63 i.e. that the usual pH of acid effluents will always be lower than this value.
• the virgin and modified membranes are analyzed by XPS.
• the virgin PVDF membrane ( Figure 5A) shows a double peak centered on 287 eV.
• the first at 285 eV corresponds to the carbons (Cls) bearing the hydrogen atoms of the PVDF and the second around 290 eV corresponds to the carbons carrying the fluorine atoms of the PVDF.
• the peak centered on 685 eV corresponds directly to the fluorine atoms of PVDF (Fis).
• the grafting of the PVDF membrane by the PAA, PVDF-g-PAA is characterized (FIG. 5B) by the appearance of an intense band at 532 eV associated with the oxygen atoms (Ois) of the PAA.
• the peak of carbon becomes predominantly centered on 285 eV.
• the peak Fis decreases in intensity due to the presence of PAA film which covers the PVDF.
• the modification with the polyaniline thin film results mainly in the appearance of the peak centered on 400 eV Nls and in the relative decrease of the peaks Fis and Ois.
• the film can be estimated at a thickness of a few nanometers.
• the stability of the grafted layer is demonstrated by the fact that the spectra shown above are systematically obtained after a long ultrasound pass. Some samples even remained for one week in 0.5M hydrochloric acid.
• cation exchange membranes modified by a surface cationic layer are preferentially permeable to low valence rather than higher valence cations. In the same way, these membranes are more permeable to small hydrated cations than to larger ones because of electrostatic repulsions and small pore size.
• the number of hydrogen and nickel ions transporting through the membrane can be determined from the composition of the anode compartment before and after electrodialysis, according to the equation:
• c 2+ and c t are respectively the concentrations of the Ni 2+ and H + cations on the membrane surface on the desalted solution side during the electrolysis.
• Figure 7 depicts the ion exchange isotherm for the modified membrane. It is observed that the amount of nickel absorbed is slightly larger in the modified membrane than in the virgin.
• the membrane conductivity K m is calculated using the following relation:
• the value of 40.2 obtained with the modified membrane is comparable with that of 39.8; 37.9 or 38.7 for Ni 2+ , Cu 2+ or Zn 2+ respectively and obtained with high selectivity commercial membranes such as CMS and reported in the literature [3,20].
• a thin layer of polyaniline type polymer was grafted onto the surface of a cation exchange membrane by a very simple method, based on diazonium salts to improve selectivity to monovalent ions.

Landscapes

• Chemical & Material Sciences (AREA)
• Manufacturing & Machinery (AREA)
• Engineering & Computer Science (AREA)
• Chemical Kinetics & Catalysis (AREA)
• Inorganic Chemistry (AREA)
• Health & Medical Sciences (AREA)
• Materials Engineering (AREA)
• Medicinal Chemistry (AREA)
• Polymers & Plastics (AREA)
• Organic Chemistry (AREA)
• Transplantation (AREA)
• Manufacture Of Macromolecular Shaped Articles (AREA)
• Separation Using Semi-Permeable Membranes (AREA)
• Water Treatment By Electricity Or Magnetism (AREA)
• Addition Polymer Or Copolymer, Post-Treatments, Or Chemical Modifications (AREA)

Applications Claiming Priority (2)

Publications (1)

Family

ID=42541568

Family Applications (1)

Country Status (5)

Families Citing this family (6)

Family Cites Families (6)

• 2009
  • 2009-12-18 FR FR0959191A patent/FR2954180B1/fr not_active Expired - Fee Related
• 2010
  • 2010-12-16 WO PCT/EP2010/070003 patent/WO2011073363A1/fr active Application Filing
  • 2010-12-16 US US13/516,674 patent/US20120312688A1/en not_active Abandoned
  • 2010-12-16 EP EP10788350A patent/EP2513205A1/de not_active Withdrawn
  • 2010-12-16 JP JP2012543774A patent/JP2013514417A/ja active Pending

Non-Patent Citations (1)

Also Published As

Similar Documents

Legal Events