EP3959004A1 - Method for manufacturing a membrane with high percolation power - Google Patents

Method for manufacturing a membrane with high percolation power

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Publication number
EP3959004A1
EP3959004A1 EP20731529.2A EP20731529A EP3959004A1 EP 3959004 A1 EP3959004 A1 EP 3959004A1 EP 20731529 A EP20731529 A EP 20731529A EP 3959004 A1 EP3959004 A1 EP 3959004A1
Authority
EP
European Patent Office
Prior art keywords
membrane
mixture
manufacturing
aqueous solution
cationic polymer
Prior art date
Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
Pending
Application number
EP20731529.2A
Other languages
German (de)
French (fr)
Inventor
Thierry Vincent
Eric Guibal
Current Assignee (The listed assignees may be inaccurate. Google has not performed a legal analysis and makes no representation or warranty as to the accuracy of the list.)
Institut Mines Telecom IMT
Original Assignee
Institut Mines Telecom IMT
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Application filed by Institut Mines Telecom IMT filed Critical Institut Mines Telecom IMT
Publication of EP3959004A1 publication Critical patent/EP3959004A1/en
Pending legal-status Critical Current

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    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
    • B01J—CHEMICAL OR PHYSICAL PROCESSES, e.g. CATALYSIS OR COLLOID CHEMISTRY; THEIR RELEVANT APPARATUS
    • B01J20/00—Solid sorbent compositions or filter aid compositions; Sorbents for chromatography; Processes for preparing, regenerating or reactivating thereof
    • B01J20/28—Solid sorbent compositions or filter aid compositions; Sorbents for chromatography; Processes for preparing, regenerating or reactivating thereof characterised by their form or physical properties
    • B01J20/28054—Solid sorbent compositions or filter aid compositions; Sorbents for chromatography; Processes for preparing, regenerating or reactivating thereof characterised by their form or physical properties characterised by their surface properties or porosity
    • B01J20/28078—Pore diameter
    • 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
    • B01D67/0002—Organic membrane manufacture
    • B01D67/0006—Organic membrane manufacture by chemical reactions
    • 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
    • B01D67/0002—Organic membrane manufacture
    • B01D67/0009—Organic membrane manufacture by phase separation, sol-gel transition, evaporation or solvent quenching
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
    • B01D—SEPARATION
    • B01D69/00—Semi-permeable membranes for separation processes or apparatus characterised by their form, structure or properties; Manufacturing processes specially adapted therefor
    • B01D69/14—Dynamic membranes
    • B01D69/141—Heterogeneous membranes, e.g. containing dispersed material; Mixed matrix membranes
    • B01D69/145—Heterogeneous membranes, e.g. containing dispersed material; Mixed matrix membranes containing embedded catalysts
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
    • B01D—SEPARATION
    • B01D69/00—Semi-permeable membranes for separation processes or apparatus characterised by their form, structure or properties; Manufacturing processes specially adapted therefor
    • B01D69/14—Dynamic membranes
    • B01D69/141—Heterogeneous membranes, e.g. containing dispersed material; Mixed matrix membranes
    • B01D69/148—Organic/inorganic mixed matrix membranes
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
    • B01D—SEPARATION
    • B01D71/00—Semi-permeable membranes for separation processes or apparatus characterised by the material; Manufacturing processes specially adapted therefor
    • B01D71/06—Organic material
    • B01D71/08—Polysaccharides
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
    • B01D—SEPARATION
    • B01D71/00—Semi-permeable membranes for separation processes or apparatus characterised by the material; Manufacturing processes specially adapted therefor
    • B01D71/06—Organic material
    • B01D71/58—Other polymers having nitrogen in the main chain, with or without oxygen or carbon only
    • B01D71/60—Polyamines
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
    • B01D—SEPARATION
    • B01D71/00—Semi-permeable membranes for separation processes or apparatus characterised by the material; Manufacturing processes specially adapted therefor
    • B01D71/06—Organic material
    • B01D71/58—Other polymers having nitrogen in the main chain, with or without oxygen or carbon only
    • B01D71/60—Polyamines
    • B01D71/601—Polyethylenimine
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
    • B01J—CHEMICAL OR PHYSICAL PROCESSES, e.g. CATALYSIS OR COLLOID CHEMISTRY; THEIR RELEVANT APPARATUS
    • B01J20/00—Solid sorbent compositions or filter aid compositions; Sorbents for chromatography; Processes for preparing, regenerating or reactivating thereof
    • B01J20/02—Solid sorbent compositions or filter aid compositions; Sorbents for chromatography; Processes for preparing, regenerating or reactivating thereof comprising inorganic material
    • B01J20/10—Solid sorbent compositions or filter aid compositions; Sorbents for chromatography; Processes for preparing, regenerating or reactivating thereof comprising inorganic material comprising silica or silicate
    • B01J20/103—Solid sorbent compositions or filter aid compositions; Sorbents for chromatography; Processes for preparing, regenerating or reactivating thereof comprising inorganic material comprising silica or silicate comprising silica
    • B—PERFORMING OPERATIONS; TRANSPORTING
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    • B01J20/02—Solid sorbent compositions or filter aid compositions; Sorbents for chromatography; Processes for preparing, regenerating or reactivating thereof comprising inorganic material
    • B01J20/20—Solid sorbent compositions or filter aid compositions; Sorbents for chromatography; Processes for preparing, regenerating or reactivating thereof comprising inorganic material comprising free carbon; comprising carbon obtained by carbonising processes
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
    • B01J—CHEMICAL OR PHYSICAL PROCESSES, e.g. CATALYSIS OR COLLOID CHEMISTRY; THEIR RELEVANT APPARATUS
    • B01J20/00—Solid sorbent compositions or filter aid compositions; Sorbents for chromatography; Processes for preparing, regenerating or reactivating thereof
    • B01J20/22—Solid sorbent compositions or filter aid compositions; Sorbents for chromatography; Processes for preparing, regenerating or reactivating thereof comprising organic material
    • B01J20/26—Synthetic macromolecular compounds
    • B01J20/265—Synthetic macromolecular compounds modified or post-treated polymers
    • B01J20/267—Cross-linked polymers
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
    • B01J—CHEMICAL OR PHYSICAL PROCESSES, e.g. CATALYSIS OR COLLOID CHEMISTRY; THEIR RELEVANT APPARATUS
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    • B01J20/28—Solid sorbent compositions or filter aid compositions; Sorbents for chromatography; Processes for preparing, regenerating or reactivating thereof characterised by their form or physical properties
    • B01J20/28002—Solid sorbent compositions or filter aid compositions; Sorbents for chromatography; Processes for preparing, regenerating or reactivating thereof characterised by their form or physical properties characterised by their physical properties
    • B01J20/28011—Other properties, e.g. density, crush strength
    • B—PERFORMING OPERATIONS; TRANSPORTING
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    • B01J20/00—Solid sorbent compositions or filter aid compositions; Sorbents for chromatography; Processes for preparing, regenerating or reactivating thereof
    • B01J20/28—Solid sorbent compositions or filter aid compositions; Sorbents for chromatography; Processes for preparing, regenerating or reactivating thereof characterised by their form or physical properties
    • B01J20/28014—Solid sorbent compositions or filter aid compositions; Sorbents for chromatography; Processes for preparing, regenerating or reactivating thereof characterised by their form or physical properties characterised by their form
    • B01J20/28028—Particles immobilised within fibres or filaments
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
    • B01J—CHEMICAL OR PHYSICAL PROCESSES, e.g. CATALYSIS OR COLLOID CHEMISTRY; THEIR RELEVANT APPARATUS
    • B01J20/00—Solid sorbent compositions or filter aid compositions; Sorbents for chromatography; Processes for preparing, regenerating or reactivating thereof
    • B01J20/28—Solid sorbent compositions or filter aid compositions; Sorbents for chromatography; Processes for preparing, regenerating or reactivating thereof characterised by their form or physical properties
    • B01J20/28014—Solid sorbent compositions or filter aid compositions; Sorbents for chromatography; Processes for preparing, regenerating or reactivating thereof characterised by their form or physical properties characterised by their form
    • B01J20/28033—Membrane, sheet, cloth, pad, lamellar or mat
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
    • B01J—CHEMICAL OR PHYSICAL PROCESSES, e.g. CATALYSIS OR COLLOID CHEMISTRY; THEIR RELEVANT APPARATUS
    • B01J20/00—Solid sorbent compositions or filter aid compositions; Sorbents for chromatography; Processes for preparing, regenerating or reactivating thereof
    • B01J20/28—Solid sorbent compositions or filter aid compositions; Sorbents for chromatography; Processes for preparing, regenerating or reactivating thereof characterised by their form or physical properties
    • B01J20/28014—Solid sorbent compositions or filter aid compositions; Sorbents for chromatography; Processes for preparing, regenerating or reactivating thereof characterised by their form or physical properties characterised by their form
    • B01J20/28047—Gels
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
    • B01J—CHEMICAL OR PHYSICAL PROCESSES, e.g. CATALYSIS OR COLLOID CHEMISTRY; THEIR RELEVANT APPARATUS
    • B01J23/00—Catalysts comprising metals or metal oxides or hydroxides, not provided for in group B01J21/00
    • B01J23/38—Catalysts comprising metals or metal oxides or hydroxides, not provided for in group B01J21/00 of noble metals
    • B01J23/40—Catalysts comprising metals or metal oxides or hydroxides, not provided for in group B01J21/00 of noble metals of the platinum group metals
    • B01J23/44—Palladium
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
    • B01J—CHEMICAL OR PHYSICAL PROCESSES, e.g. CATALYSIS OR COLLOID CHEMISTRY; THEIR RELEVANT APPARATUS
    • B01J23/00—Catalysts comprising metals or metal oxides or hydroxides, not provided for in group B01J21/00
    • B01J23/90—Regeneration or reactivation
    • B01J23/96—Regeneration or reactivation of catalysts comprising metals, oxides or hydroxides of the noble metals
    • B01J35/59—
    • B01J35/60—
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
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    • B01J37/00—Processes, in general, for preparing catalysts; Processes, in general, for activation of catalysts
    • B01J37/02—Impregnation, coating or precipitation
    • B01J37/0201—Impregnation
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
    • B01J—CHEMICAL OR PHYSICAL PROCESSES, e.g. CATALYSIS OR COLLOID CHEMISTRY; THEIR RELEVANT APPARATUS
    • B01J37/00—Processes, in general, for preparing catalysts; Processes, in general, for activation of catalysts
    • B01J37/02—Impregnation, coating or precipitation
    • B01J37/03—Precipitation; Co-precipitation
    • B01J37/036—Precipitation; Co-precipitation to form a gel or a cogel
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
    • B01J—CHEMICAL OR PHYSICAL PROCESSES, e.g. CATALYSIS OR COLLOID CHEMISTRY; THEIR RELEVANT APPARATUS
    • B01J38/00—Regeneration or reactivation of catalysts, in general
    • B01J38/48—Liquid treating or treating in liquid phase, e.g. dissolved or suspended
    • 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
    • C08J3/00—Processes of treating or compounding macromolecular substances
    • C08J3/02—Making solutions, dispersions, lattices or gels by other methods than by solution, emulsion or suspension polymerisation techniques
    • C08J3/03—Making solutions, dispersions, lattices or gels by other methods than by solution, emulsion or suspension polymerisation techniques in aqueous media
    • C08J3/075—Macromolecular gels
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
    • B01D—SEPARATION
    • B01D2323/00—Details relating to membrane preparation
    • B01D2323/30—Cross-linking
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
    • B01D—SEPARATION
    • B01D2325/00—Details relating to properties of membranes
    • B01D2325/02—Details relating to pores or porosity of the membranes
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
    • B01D—SEPARATION
    • B01D2325/00—Details relating to properties of membranes
    • B01D2325/30—Chemical resistance
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
    • B01D—SEPARATION
    • B01D2325/00—Details relating to properties of membranes
    • B01D2325/48—Antimicrobial properties
    • 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
    • C08J2305/00—Characterised by the use of polysaccharides or of their derivatives not provided for in groups C08J2301/00 or C08J2303/00
    • C08J2305/04—Alginic acid; Derivatives thereof
    • 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
    • C08J2479/00—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 C08J2461/00 - C08J2477/00
    • C08J2479/02—Polyamines
    • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
    • Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
    • Y02P—CLIMATE CHANGE MITIGATION TECHNOLOGIES IN THE PRODUCTION OR PROCESSING OF GOODS
    • Y02P20/00—Technologies relating to chemical industry
    • Y02P20/50—Improvements relating to the production of bulk chemicals
    • Y02P20/584—Recycling of catalysts

Definitions

  • the invention relates to a method of manufacturing a membrane with high percolation power due to high macroporosity.
  • Sorption is the simplest, most effective and the least expensive technique to implement.
  • the adsorbents commonly used for sorption are materials such as activated carbon.
  • these materials have the disadvantages of being unstable, present poor mechanical properties, to be difficult to recover after sorption thereby generating a 2 nd source of pollution.
  • Filter membranes in particular those used in membrane processes such as microfiltration, ultrafiltration, reverse osmosis
  • their life cycle in particular their elimination at the end of the cycle
  • toxic pollutants such as volatile organic compounds
  • a certain number of drawbacks are liable to limit its use: flow rates, cost, clogging phenomena.
  • the generation of large volumes of concentrates that are difficult to recover is also a limitation.
  • the percolation properties of current filter membranes are sometimes made difficult (in particular as a function of their porosity, of the presence of particles in suspension) by pressure drops and / or clogging problems.
  • filter membranes of the “sponge” type providing both a filtering structure (for simplified and low-energy implementation: gravity percolation, for example), as well as a specific reactivity associated with the presence of functional groups.
  • adsorbent sponges with high macroporosity can find fields of application in supported catalysis.
  • the immobilization of complex and expensive catalytic formulations requires good containment of these metallic or organometallic phases, combined with optimized material transfer properties for optimizing the conditions and performance of catalytic reactions.
  • the supports on which palladium nanoparticles were immobilized consisted of inorganic materials such as mesoporous silica, zeolites and activated carbon.
  • inorganic materials such as mesoporous silica, zeolites and activated carbon.
  • the palladium nanoparticles were often leached out during the chemical reaction; which led to losses of catalyst.
  • the losses of such catalysts were increased due to the fact that they were not easily recoverable at the end of the chemical reaction, and this despite the implementation of separation techniques (centrifugation and filtration) costly in time and in energy, and therefore making the catalytic support based on inorganic material inefficient for its use on an industrial scale.
  • the inventors have overcome all these drawbacks detailed above with regard to filter materials intended for a wide variety of applications such as the treatment of liquid effluents, but also their use as supports (functionalized or not) for heterogeneous catalysis or for anti-microbial products.
  • the inventors have in fact developed a new process for manufacturing a membrane with high percolation power which perfectly meets these objectives.
  • the invention relates to a method of manufacturing a membrane which comprises at least the following steps:
  • the mixture is left to mature to cause the ionic interaction between positively charged groups of the cationic polymer and negatively charged groups of the anionic polymer, until a membrane is obtained within the mixture in the form of a hydrogel;
  • step d) the crosslinked membrane obtained at the end of step d) is dried.
  • the cationic polymer has a molecular weight greater than 40,000 g / mol. In addition, it exhibits positive charges over a wide pH range which is between 5 and 8.
  • the cationic polymer can be chosen from polyethyleneimine (hereinafter “PEI”), poly (allylamine hydrochloride), chitosans and proteins (for example gelatins).
  • the anionic polymer has a viscosity of between 0.4 and 0.5 Pa.s for a 1% solution by mass of this polymer.
  • it advantageously exhibits negative charges at neutral or slightly acidic pH (namely for pH values between 5 and 7).
  • the anionic polymer can be chosen from poly (acrylic acid), pectin, carrageenan, alginate and poly (styrenesulfonate).
  • the mixture of step a) can comprise, in percentages by mass expressed relative to the mass of said mixture:
  • Step a) can be carried out by gradually adding the aqueous solution of cationic polymer to a container containing the aqueous solution of anionic polymer.
  • step a) at least one solid compound is added to the mixture.
  • This solid compound can be chosen from activated carbon, silica and clay.
  • This solid compound will give the membrane new reactive functions or new functionalities.
  • these examples of solid compounds are porous and carry functional groups having different affinities with respect to contaminants; which makes it possible to broaden the possible applications of the membrane.
  • their porous and / or polar / non-polar characteristics can give it properties of immobilization of organic compounds (for example essential oils, perfumes or even any chemical compound used for liquid / liquid extractions).
  • the solid compound is rehydrated before its introduction into the mixture in order to facilitate its dispersion in this mixture which is viscous owing to the presence of the two polymers.
  • this addition represents, as a percentage by mass expressed relative to the dry mass of the membrane, between 0.05% and 1.2%. More precisely, when the compound is activated carbon or silica, the mass percentage can be between 0.05% and 0.4%, preferably between 0.1% and 0.3%. In the case of clay, the mass percentage can be between 0.4% and 1.2%, preferably between 0.5% and 0.8%.
  • Step b) can be carried out at room temperature with stirring at a speed of between 16,000 revolutions / minute and 22,000 revolutions / minute, preferably between 19,000 revolutions / minute and 21,000 revolutions / minute.
  • the duration of step b) can be between 30 seconds and 2 minutes, preferably between 40 seconds and 80 seconds.
  • the mixture can be poured into a mold (for example a polypropylene box) and the maturation step c) is then carried out.
  • a mold for example a polypropylene box
  • the geometry of the mold will give a shape to the membrane which will be obtained at the end of the process according to the invention.
  • the varied geometries of the molds allow the production of membranes of different shapes and sizes.
  • a membrane is formed within the mixture in the form of a hydrogel due to the ionic interaction between positively charged groups of the cationic polymer (for example the amino functions of the PEI, or of a chitosan) and negatively charged groups of the anionic polymer (for example the carboxylic functions of the alginate or the sulfonic functions of a carrageenan).
  • hydrogel is meant according to step c), a material forming a wet membrane and consisting of a network of two cationic and anionic polymers. This polymer network has a structure which does not result from ionotropic gelation, but indeed from ionic bonds between the aforementioned groups of opposite charges and which already has macroporosity.
  • Step c) can be carried out over a temperature range varying between -80 ° C and 50 ° C (therefore including freezing of the mixture for negative temperatures). This is not critical for the interaction between positively charged groups of the cationic polymer and negatively charged groups of the anionic polymer to take place. Thus, it can be carried out at room temperature, it can also be carried out, in one embodiment of the invention, at a temperature between -10 ° C and -30 ° C. In this last mode, one obtains a mechanically stable membrane with a remarkable elasticity (namely that it can accept important deformations). In the case of freezing, thawing takes place during step d) during which the crosslinking agent is added.
  • step c) however has an influence on the reaction kinetics (or in other words on the quality of the ionic interactions between the cationic polymer and the anionic polymer), and consequently on the process of structuring of the membrane; which induces the textural characteristics (in particular the macroporosity characteristics) of the membrane obtained according to the manufacturing process according to the invention.
  • step c) advantageously, all the charged groups of the cationic and anionic polymers respectively do not necessarily interact. Indeed, free groups (or charged depending on the intended application) will have to remain for the consecutive step d) of crosslinking, depending on the desired crosslinking, but also because of their involvement depending on the use which is then made of the membrane. resulting from the process of the invention. It is of course within the competence of those skilled in the art to adapt the conditions of step c) to the quality of the expected membrane. Thus, if it is used to retain metal ions, it will be necessary to ensure that reactive groups (cationic and anionic of the starting polymers) remain free.
  • the rate of positively charged groups and / or of negatively charged groups which have remained free is less than or equal to 50%, for example example of 30-50%. If it is necessary to control this rate, a person skilled in the art, on the basis of his general knowledge, can in particular act on the ratio of the concentration of the cationic polymer to that of the anionic polymer, over the duration of the step. b).
  • the membrane is washed at least once with water, preferably with demineralized water. This makes it possible to remove the reagents and monomers which have not reacted between the various constituents in step c), as well as the labile parts.
  • step d) at least one crosslinking agent is added to the mixture which contains the membrane in the form of a hydrogel from step c).
  • This step of crosslinking the network formed in step c) generates an additional mesh to form a new crosslinked network which then contributes to reinforcing the structuring of the membrane and in particular to freezing the porous network.
  • This additional mesh can be the result of a crosslinking of the chains of the cationic polymer between them, of a crosslinking of the chains of the anionic polymer between them, or of a crosslinking of the chains of the cationic polymer and of the chains of the anionic polymer, according to the crosslinking agent involved, or even a combination of these mechanisms with the use of several crosslinking agents.
  • crosslinking takes place between the neighboring chains.
  • Those skilled in the art are able to select the crosslinking agent (s) for this step, in particular as a function of the application which is made of the high percolation membrane manufactured. It should be observed that this step d) can involve groups of said cationic and / or anionic polymers, which are also the groups involved in step c); it is therefore in this case necessary that all these groups have not been engaged in step c).
  • the crosslinking agent is suitably chosen according to the nature of the cationic polymer.
  • the crosslinking agent can be glutaraldehyde.
  • the cationic polymer is PEI
  • glutaraldehyde the aldehyde function of the latter will react with the free amino functions of the PEI. This is a Schiff base type reaction.
  • the percentage by weight of the crosslinking agent can be between 0.1% and 1%, relative to the weight of the mixture from step a).
  • the percentage by weight of the crosslinking agent is advantageously between 0.1% and 0.6%.
  • step d) the crosslinking agent is advantageously added to the mixture with slow stirring (for example by subjecting the mixture to a “back and forth” movement: between 20 and 40 movements per minute).
  • the crosslinked membrane is washed at least once with water, preferably with demineralized water. This makes it possible to eliminate the reagents and monomers which have not reacted between the various constituents, as well as the labile parts.
  • step e) the membrane thus obtained is dried.
  • the drying is advantageously carried out at ambient temperature under an air flow (for example with an extractor hood).
  • This process does not require a complex and energy-consuming device; which makes the originality and the interest of the process according to the invention.
  • a membrane which has the following properties:
  • a porosity such that the percentage of void is between 90% and 96%, preferably around 95%;
  • the manufacturing process according to the invention has the advantage of not requiring any sophisticated drying process to maintain the high porosity of the membrane.
  • the process according to the invention makes use of simple steps of agitation, gelation and crosslinking, as well as of drying at room temperature. It does not necessarily require a freeze-drying step or the production of a cryogel.
  • the sophisticated drying step as described above is perfectly optional in the context of the invention and is implemented only if it is desired to have a membrane having a bi-structure, namely a macroporous structure with a micro- or meso-porous surface.
  • the manufacturing process according to the invention has the advantage of obtaining a mechanically stable membrane with good elasticity, in particular when, in step c), the mixture is allowed to mature by freezing it.
  • the method according to the invention allows the easy manufacture of membranes under better energy conditions.
  • the invention also relates to a membrane with high percolation power capable of being obtained by the above process, in particular as obtained by this process.
  • it can be an adsorbent membrane, it can also be a membrane not involving any interaction of its groups.
  • a subject of the invention is also the use of the membrane obtained according to the manufacturing process for the treatment of liquid or gaseous effluents.
  • a subject of the invention is also the use of the membrane obtained according to the manufacturing process as a support for heterogeneous catalysis. This support has the advantage of being able to easily recover the catalysts at the end of their life cycle thanks to easy removal from the membrane, for example by thermal degradation. This thus allows the recycling of precious metals which are used as catalyst for heterogeneous catalysis.
  • a subject of the invention is also the use of the membrane obtained according to the manufacturing process as an anti-microbial support.
  • the membrane can easily retain anti-microbial compounds such as metal cations (for example Ag (l), Zn (II), Cu (II), Ni (II)) which have biocidal properties.
  • the membrane can also exhibit antimicrobial properties if it is chemically modified by the grafting of quaternary amines, for example at the level of the cationic polymer. This chemical modification may have been carried out on the cationic polymer before the implementation of the manufacturing process according to the invention or even before or after the drying step.
  • the grafting of quaternary amines is perfectly within the reach of a person skilled in the art, as are these antimicrobial properties obtained by the quaternization of cationic polymers.
  • the membrane obtained with the process according to the invention on which metal cations have been adsorbed or which has been chemically modified by quaternization so that it has biocidal properties can thus be used as a filter medium for microbial decontamination. .
  • FIG. 1 shows a graph of the changes in the binding capacity noted “q eq " of chromium (VI) (hereinafter abbreviated “Cr (VI)” and of total chromium (hereinafter “Cr (total”) as a function of respectively the residual concentration C eq in Cr (VI) and Cr (total) after experiments of adsorption of chromium ions on a membrane obtained according to a 1 st embodiment of the manufacturing process according to the invention.
  • FIG. 2 represents a photograph of a membrane obtained according to a 2 nd embodiment of the manufacturing method according to the invention.
  • FIG. 3 is a graph showing the changes as a function of the hydrogenation reaction time of 3-nitrophenol (hereinafter abbreviated "3-NP") of the relative residual concentration of palladium noted “C t / Co” for 3 membranes d 'different thicknesses and which were obtained according to this 2 nd embodiment of the manufacturing process according to the invention.
  • 3-NP 3-nitrophenol
  • FIG. 4 is a graph of the modeling of the kinetic profiles by the pseudo first order equation (ln (Ct / Co) as a function of the reaction time established from the relative residual concentrations of palladium recorded.
  • FIG. 5 represents a graph of the breakthrough curves obtained with other experiments on the hydrogenation reaction of 3-NP.
  • FIG. 6 shows a photomicrograph of a membrane produced according to the invention illustrating the macroporosity of the material (scanning electron microscope).
  • FIG. 7 represents a photograph illustrating the high percolation power (by gravity drainage) of a membrane produced according to the invention during the flow of a liquid.
  • FIG. 8 shows a photograph of a membrane produced according to the invention (plate, 20 x 10 cm).
  • FIG. 9 represents a photograph of the internal macroporosity of the membranes produced according to the invention (in section, after cutting with a punch).
  • the membrane was washed 5 times with deionized water.
  • the washed membrane was suspended in 300 mL of demineralized water to which was added 4 mL of an aqueous solution of glutaraldehyde at a mass content of 50% so as to effect crosslinking of the membrane.
  • the membrane was subjected to moderate agitation of 30 "back and forth" movements per minute for 24 hours.
  • the membrane was rinsed (6 times) with 300 mL of deionized water, then dried at room temperature for 2 days.
  • the membrane thus obtained exhibited the following characteristics: a porosity (measured with a pycnometer) of 93.4%; 94% stability to attrition;
  • pHpHpzc a zero charge point pH
  • the stability of the membrane was determined by subjecting a sample of the membrane in the form of a 25 mm diameter disc immersed in 20 mL of water to stirring at 150 rpm for 72 hours. Then, the membrane was dried and weighed. Stability is the percentage of membrane remaining at the end of this agitation relative to the initial mass of membrane. The value of 94% testifies to a very good stability to attrition of the membrane and to the maintenance of its integrity when it is subjected to strong agitation in water.
  • the water flow was determined by measuring the time required for 100 mL of water to pass through a membrane sample with an area of 4.64 cm 2 , at 20 ° C and a pressure of 0.006 bar.
  • the value of the water flow (in natural percolation) of 33.6 mL / (cm 2 .min) testifies to the excellent percolation properties of the membrane.
  • FIG. 7 illustrates the natural flow by gravity drainage through the macroporosity of membranes with high percolation power.
  • the membrane thus obtained was subjected to sorption experiments with a solution containing Cr (VI) ions in order to characterize its adsorption properties.
  • the device used for these experiments consisted of a device operating continuously for the recirculation of solutions containing metal ions which included:
  • a support configured to contain the membrane and allow the circulation of the metal ion solution through said membrane;
  • the Cr (VI) concentration was determined with an ultraviolet spectrophotometer sold by the company Shimadzu under the trade name UV-1650PC at a wavelength of 540 nm by the colorimetric method using diphenylcarbazone.
  • the total Cr concentration (ie the sum of the Cr (VI) and Cr (III) ions) was determined by atomic emission spectrometry with induced plasma with a spectrometer sold by the company Horiba under the trade name Activa.
  • the concentration of Cr (III) was determined by subtracting the concentration of Cr (total) from the concentration of Cr (VI).
  • the adsorption isotherm was determined with the device described above by circulating in a loop at 20 ° C and continuously for 96 hours 50 mL of Cr (VI) solutions at a pH of 2 and at initial concentrations. between 20 and 300 mg / L. The circulation rate was 15 mL / minute.
  • FIG. 1 is a graph of the changes in the binding capacity q eq of Cr (VI) and of Cr (total) as a function of the residual concentration C eq in Cr (VI) and Cr (total) respectively.
  • the maximum adsorption capacity exceeds 300 mg Cr (VI) / g.
  • This maximum binding capacity is very high (representing more than 6 mmol Cr (VI) / g of adsorbent).
  • the slope at the origin for Cr (VI) is almost vertical. This demonstrates the strong affinity of the membrane obtained with the manufacturing process according to the invention for chromate ions.
  • the slope at the origin for Cr (total) is lower. This is linked to mechanisms of in situ reduction of Cr (VI) on the membrane in an acidic medium.
  • a volume of 100 mL of a 4% alginate solution (by mass) was diluted with 400 mL of demineralized water so as to obtain a 1st solution.
  • the mixture was poured into a polypropylene mold avoiding the formation of bubbles and the whole was left at room temperature for 24 hours.
  • a membrane was obtained due to the gelation reaction of the alginate with the PEI.
  • the membrane obtained was washed 5 times with demineralized water in order to remove the free reactants. 300 mL of demineralized water were added to the washed membrane, then 2.5 mL of an aqueous solution of glutaraldehyde at a mass content of 50% so as to reinforce the crosslinking of the membrane.
  • the membrane was subjected to moderate agitation consisting of a "back and forth" motion of 30 strokes / minute for 24 hours.
  • the membrane was washed 4 times with deionized water, then dried at room temperature for 2 days.
  • the membrane thus obtained exhibited the following characteristics: a porosity (measured with a pycnometer) of 70.93%;
  • Stability was determined in the same way as for the 1st set of experiments. The value of 97% testifies to a very good stability to attrition of the membrane and to the maintenance of its integrity when it is subjected to strong agitation in water.
  • the water flow was determined in the same way as for the 1 st series of experiments.
  • the value of 24.8 mL / (cm 2 .min) shows excellent percolation properties of the membrane.
  • FIG. 2 represents a photograph of a sample of this adsorbent membrane 1 which was thus obtained.
  • the sample is 55 mm in length and has a diameter of 25 mm.
  • the membrane was cut into 25 mm diameter disks.
  • a disc (of dry mass 250 mg) was then placed in the support configured to contain the membrane of the device described in the 1st series of experiments so as to produce a fixed bed column.
  • One liter of a solution of Palladium (II) (hereinafter abbreviated: "Pd (II)") of variable concentration, between 10 and 50 mg / L, the pH of which has been adjusted to 1 with acid sulfuric acid was circulated in a loop within this device for 24 hours with a flow rate of 30 mL / min.
  • the optimum conditions for the binding of palladium on the membrane (in other words "the best maximum yield of use of palladium") were obtained when its concentration was 28 mg Pd / L.
  • the column was rinsed 4 times with deionized water at a pH of 1.
  • the membrane was not dried before proceeding with the reduction of the metal.
  • the reduction of the Pd (II) immobilized on the membrane was carried out by hydrazine hydrate (chemical formula: IShH ⁇ PhO) at a concentration of 0.03 mol / L in 200 mL of an alkaline solution (at a concentration of 0.5 mmol / L of NaOH) with stirring at 60 ° C. for 5 hours.
  • hydrazine hydrate chemical formula: IShH ⁇ PhO
  • the catalytic membrane A membrane on which palladium was adsorbed was obtained. This membrane is hereinafter abbreviated "the catalytic membrane”.
  • the size of the palladium nanoparticles varied between 4.5 and 10.5 nm.
  • the catalytic membrane was recirculated in a loop for 12 minutes with 100 mL of a solution of 3-NP at 50 mg 3-NP / L the pH of which was adjusted to 2.84 in the presence of formic acid at a concentration of 0.2% by mass.
  • the formic acid concentration was set in molar excess with respect to 3-NP (formic acid / 3-NP molar ratio of 160/1).
  • the recirculation rate was 50 mL / min.
  • the 3-NP concentration was measured spectrophotometrically at 332 nm. To do this, the samples taken were acidified with 20 ⁇ L of a 5% by mass solution of sulfuric acid prior to the spectrophotometric analysis.
  • FIG. 3 is a graph showing the changes as a function of the hydrogenation reaction time of the relative residual concentration of palladium noted “C t / Co” for the 3 membranes tested:
  • FIG. 4 is a graph of the modeling of the kinetic profiles by the pseudo first order equation (ln (Ct / Co) as a function of the reaction time for the 3 catalytic membranes tested:
  • the catalytic membrane was supplied with this solution of 3- NP at these same circulation rates of 20 or 30 mL / minute but by regenerating it (by simple rinsing with demineralized water using a volume corresponding to approximately 9 times the volume occupied by said membrane) when the volume of 3-NP which had circulated through the catalytic membrane had reached the values of 40 mL and 80 mL.
  • FIG. 5 represents a graph of the breakthrough curves obtained with these experiments. This is the change in the residual concentration of 3-NP as a function of the volume of the 3-NP solution passed through the catalytic membrane when:
  • the breakthrough curves show a progressive increase in the residual concentration of 3-NP as a function of the volume of the 3-NP solution which has passed through the catalytic membrane. Increasing the flow rate increases the slope of the breakthrough curve (due to insufficient residence time in the catalytic membrane).
  • This catalytic reaction for hydrogenation of 3-NP clearly illustrates the possibility of using the membranes with high percolation power obtained with the manufacturing process according to the invention for the immobilization of catalytic metals and the synthesis of catalytic supports to be used in dynamic regime at high filtration rate, with confinement of nanoparticles.
  • these membranes have the advantage of being able to easily recover the catalysts at the end of their life cycle, for example by thermal degradation of the membranes. The precious metals which constitute the catalysts are thus recycled.

Abstract

The invention relates to a method for manufacturing a membrane (1), which comprises the following steps: a) a mixture is prepared that contains at least: - an aqueous solution of cationic polymer with a pH between 5 and 8, the cationic polymer having positively charged groups in said aqueous solution; an aqueous solution of anionic polymer, the anionic polymer having negatively charged groups in said aqueous solution; b) the mixture is agitated; c) the mixture is allowed to mature in order to cause ionic interaction between the positively charged groups of the cationic polymer and the negatively charged groups of the anionic polymer, until a membrane in the form of a hydrogel is obtained within the mixture; d) at least one crosslinking agent is added in such a way as to crosslink the membrane; e) the crosslinked membrane that was obtained is dried after step d). The invention also relates to the use of this membrane (1) for treating liquid or gaseous effluents, and as antimicrobial support or for heterogeneous catalysis.

Description

PROCEDE DE FABRICATION D'UNE MEMBRANE A HAUT POUVOIR DE PERCOLATION METHOD OF MANUFACTURING A MEMBRANE WITH HIGH PERCOLATION POWER
L'invention concerne un procédé de fabrication d'une membrane à haut pouvoir de percolation du fait d'une macroporosité élevée. The invention relates to a method of manufacturing a membrane with high percolation power due to high macroporosity.
Les étapes unitaires du génie des procédés appliqués dans des domaines comme le traitement des eaux, des gaz, la catalyse supportée, la mise en œuvre de supports anti-microbiens nécessitent une bonne gestion des propriétés de transfert de matière, de réactivité, de filtration et de percolation. La mise en œuvre de particules fines (nano- ou micrométriques) permet d'optimiser les propriétés de transfert mais au prix d'une complexification des procédés de séparation et de confinement. The unitary stages of process engineering applied in fields such as water and gas treatment, supported catalysis, the implementation of anti-microbial supports require good management of the properties of material transfer, reactivity, filtration and percolation. The use of fine particles (nano- or micrometric) makes it possible to optimize the transfer properties but at the cost of making the separation and confinement processes more complex.
Le traitement d'effluents métallifères met souvent en œuvre des procédés comme la réduction chimique, la précipitation chimique ou électrochimique, les techniques d'extraction par solvant, l'électrocoagulation, les procédés membranaires, l'adsorption sur résines échangeuses d'ions ou chélatantes, ou sur des adsorbants minéraux ou organiques tant en laboratoire que dans l'industrie. Ces procédés sont toutefois confrontés à des problèmes de coût (compétitivité), de production de déchets et sous-produits, ou d'efficacité (en rapport avec les normes de rejet) qui en limitent l'application. The treatment of metalliferous effluents often involves processes such as chemical reduction, chemical or electrochemical precipitation, solvent extraction techniques, electrocoagulation, membrane processes, adsorption on ion exchange or chelating resins , or on mineral or organic adsorbents both in the laboratory and in industry. These processes are however confronted with problems of cost (competitiveness), production of waste and by-products, or efficiency (in relation to the discharge standards) which limit their application.
Dans le cadre du traitement des eaux et plus particulièrement de la fixation des ions métalliques, les résines échangeuses d'ions conventionnelles (industrielles) requièrent souvent des procédés complexes de synthèse. In the context of water treatment and more particularly the fixing of metal ions, conventional (industrial) ion exchange resins often require complex synthesis processes.
La sorption est la technique la plus simple, efficace et la moins coûteuse à mettre en oeuvre. Les adsorbants couramment utilisés pour la sorption sont des matériaux tels que le charbon actif. Cependant, ces matériaux ont les inconvénients d'être peu stables, de présenter de mauvaises propriétés mécaniques, d'être difficilement récupérables à l'issue de la sorption générant ainsi une 2ème source de pollution. Sorption is the simplest, most effective and the least expensive technique to implement. The adsorbents commonly used for sorption are materials such as activated carbon. However, these materials have the disadvantages of being unstable, present poor mechanical properties, to be difficult to recover after sorption thereby generating a 2 nd source of pollution.
Les membranes filtrantes (notamment celles utilisées dans les procédés membranaires tels que microfiltration, ultrafiltration, osmose inverse) constituent une alternative intéressante à ces techniques. Néanmoins, leur cycle de vie (notamment leur élimination en fin de cycle) génère des polluants toxiques (tels que des composés organiques volatiles) qui requièrent des procédés de destruction contrôlée. Par ailleurs, un certain nombre d'inconvénients sont susceptibles d'en limiter l'utilisation : débits, coût, phénomènes de colmatage. La génération de gros volumes de concentrats difficilement valorisables représente également une limitation. En outre, les propriétés de percolation des membranes filtrantes actuelles sont parfois rendues difficiles (notamment en fonction de leur porosité, de la présence de particules en suspension) par des pertes de charge et/ou des problèmes de colmatage. Filter membranes (in particular those used in membrane processes such as microfiltration, ultrafiltration, reverse osmosis) constitute an interesting alternative to these techniques. However, their life cycle (in particular their elimination at the end of the cycle) generates toxic pollutants (such as volatile organic compounds) which require controlled destruction processes. Furthermore, a certain number of drawbacks are liable to limit its use: flow rates, cost, clogging phenomena. The generation of large volumes of concentrates that are difficult to recover is also a limitation. In addition, the percolation properties of current filter membranes are sometimes made difficult (in particular as a function of their porosity, of the presence of particles in suspension) by pressure drops and / or clogging problems.
Une alternative à ces matériaux consiste à réaliser des membranes filtrantes de type « éponges » apportant à la fois une structure filtrante (pour une mise en œuvre simplifiée et peu énergétique : percolation gravitaire, par exemple), ainsi qu'une réactivité spécifique associée à la présence de groupements fonctionnels. An alternative to these materials consists in making filter membranes of the “sponge” type providing both a filtering structure (for simplified and low-energy implementation: gravity percolation, for example), as well as a specific reactivity associated with the presence of functional groups.
Dans les procédés conventionnels, les techniques de fabrication de ces membranes peuvent mettre en œuvre : In conventional processes, the manufacturing techniques of these membranes can implement:
- des étapes de congélation et de lyophilisation ou de séchage (par exemple dans des conditions de dioxyde de carbone supercritique) qui sont extrêmement énergivores, et/ou - freezing and lyophilization or drying steps (for example under supercritical carbon dioxide conditions) which are extremely energy intensive, and / or
- des étapes complexes pour générer des porosités appropriées pour les applications de traitement gravitaire d'effluents. - complex steps to generate appropriate porosities for gravity effluent treatment applications.
Ces différents inconvénients rendent donc l'élaboration de ces membranes peu intéressantes pour leur production à grande échelle. These various drawbacks therefore make the development of these membranes uninteresting for their large-scale production.
Par ailleurs, au-delà de la réalisation de supports adsorbants, la fabrication d'éponges adsorbantes à forte macroporosité peut trouver des champs d'applications en catalyse supportée. En effet, l'immobilisation de formulations catalytiques complexes et coûteuses exige un bon confinement de ces phases métalliques ou organométalliques, alliées à des propriétés optimisées de transfert de matière pour l'optimisation des conditions et performances de réactions catalytiques. Moreover, beyond the production of adsorbent supports, the manufacture of adsorbent sponges with high macroporosity can find fields of application in supported catalysis. In fact, the immobilization of complex and expensive catalytic formulations requires good containment of these metallic or organometallic phases, combined with optimized material transfer properties for optimizing the conditions and performance of catalytic reactions.
A titre d'exemple, jusqu'à encore récemment, les supports sur lesquels étaient immobilisées des nanoparticules de palladium consistaient en des matériaux inorganiques tels que la silice mésoporeuse, les zéolithes et le charbon actif. Cependant, avec de tels matériaux, les nanoparticules de palladium étaient souvent lessivées au cours de la réaction chimique ; ce qui conduisait à des pertes de catalyseur. En outre, les pertes de tels catalyseurs étaient accrues du fait qu'ils n'étaient pas aisément récupérables à l'issue de la réaction chimique, et ce malgré la mise en œuvre de techniques de séparation (centrifugation et filtration) coûteuses en temps et en énergie, et donc rendant le support catalytique à base de matériau inorganique peu performant pour son utilisation à l'échelle industrielle. Faire évoluer la synthèse de catalyseurs hétérogènes vers de nouveaux supports s'inscrit donc dans la perspective d'une meilleure efficience et réutilisation de ressources coûteuses et peu disponibles. C'est pourquoi, dans le domaine de la catalyse hétérogène, on s'est orientés vers l'utilisation de supports à base de polymères afin de surmonter ces inconvénients de pertes de catalyseurs observées avec les supports conventionnels. By way of example, until recently, the supports on which palladium nanoparticles were immobilized consisted of inorganic materials such as mesoporous silica, zeolites and activated carbon. However, with such materials, the palladium nanoparticles were often leached out during the chemical reaction; which led to losses of catalyst. In addition, the losses of such catalysts were increased due to the fact that they were not easily recoverable at the end of the chemical reaction, and this despite the implementation of separation techniques (centrifugation and filtration) costly in time and in energy, and therefore making the catalytic support based on inorganic material inefficient for its use on an industrial scale. Developing the synthesis of heterogeneous catalysts towards new supports is therefore part of the perspective of better efficiency and reuse of expensive and scarce resources. This is why, in the field of heterogeneous catalysis, we have turned towards the use of supports based on polymers in order to overcome these drawbacks of catalyst losses observed with conventional supports.
Les inventeurs ont surmonté tous ces inconvénients détaillés ci-dessus quant aux matériaux filtrants destinés à des applications très variées que sont notamment le traitement d'effluents liquides, mais également leur utilisation en tant que supports (fonctionnalisés ou non) pour la catalyse hététérogène ou pour les produits anti-microbiens. The inventors have overcome all these drawbacks detailed above with regard to filter materials intended for a wide variety of applications such as the treatment of liquid effluents, but also their use as supports (functionalized or not) for heterogeneous catalysis or for anti-microbial products.
Les inventeurs ont en effet mis au point un nouveau procédé de fabrication d'une membrane à fort pouvoir de percolation qui remplit parfaitement ces objectifs. The inventors have in fact developed a new process for manufacturing a membrane with high percolation power which perfectly meets these objectives.
L'invention concerne un procédé de fabrication d'une membrane qui comprend au moins les étapes suivantes : The invention relates to a method of manufacturing a membrane which comprises at least the following steps:
a) on prépare un mélange qui contient au moins : a) a mixture is prepared which contains at least:
une solution aqueuse de polymère cationique dont le pH est compris entre 5 et 8, ledit polymère cationique présentant dans cette solution aqueuse des groupements chargés positivement; an aqueous solution of cationic polymer whose pH is between 5 and 8, said cationic polymer having positively charged groups in this aqueous solution;
une solution aqueuse de polymère anionique, ledit polymère anionique présentant dans cette solution aqueuse des groupements chargés négativement ; an aqueous solution of anionic polymer, said anionic polymer exhibiting in this aqueous solution negatively charged groups;
b) on agite le mélange ; b) the mixture is stirred;
c) on laisse maturer le mélange pour entraîner l'interaction ionique entre des groupements chargés positivement du polymère cationique et des groupements chargés négativement du polymère anionique, jusqu'à l'obtention au sein du mélange d'une membrane sous la forme d'un hydrogel ; c) the mixture is left to mature to cause the ionic interaction between positively charged groups of the cationic polymer and negatively charged groups of the anionic polymer, until a membrane is obtained within the mixture in the form of a hydrogel;
d) on ajoute au moins un agent de réticulation de manière à figer la structure de la membrane d) at least one crosslinking agent is added so as to fix the structure of the membrane
e) on sèche la membrane réticulée obtenue à l'issue de l'étape d). e) the crosslinked membrane obtained at the end of step d) is dried.
Selon l'invention, il a été déterminé qu'une plage de valeurs de pH s'étendant de 5 à 8 était optimale pour qu'à la fois, le polymère cationique présente des groupements chargés positivement et que le polymère anionique mélangé présente des groupements chargés négativement, prêts à interagir. Au sein de cette plage, l'homme du métier est à même de déterminer le pH en fonction du pKa des polymères. According to the invention, it has been determined that a range of pH values extending from 5 to 8 is optimal so that both the cationic polymer has positively charged groups and the mixed anionic polymer has groups. negatively charged, ready to interact. Within this range, those skilled in the art are able to determine the pH as a function of the pKa of the polymers.
De préférence, le polymère cationique présente un poids moléculaire supérieur à 40 000 g/mol. En outre, il présente des charges positives sur une large plage de pH qui est comprise entre 5 et 8. Le polymère cationique peut être choisi parmi la polyéthylèneimine (ci- abrégé « PEI »), le poly(hydrochlorure d'allylamine), les chitosanes et les protéines (par exemple les gélatines). Preferably, the cationic polymer has a molecular weight greater than 40,000 g / mol. In addition, it exhibits positive charges over a wide pH range which is between 5 and 8. The cationic polymer can be chosen from polyethyleneimine (hereinafter “PEI”), poly (allylamine hydrochloride), chitosans and proteins (for example gelatins).
De préférence, le polymère anionique présente une viscosité comprise entre 0,4 et 0,5 Pa.s pour une solution à 1% en masse de ce polymère. En outre, il présente avantageusement des charges négatives à pH neutre ou légèrement acide (à savoir pour des valeurs de pH comprises entre 5 et 7). Preferably, the anionic polymer has a viscosity of between 0.4 and 0.5 Pa.s for a 1% solution by mass of this polymer. In addition, it advantageously exhibits negative charges at neutral or slightly acidic pH (namely for pH values between 5 and 7).
Le polymère anionique peut être choisi parmi le poly(acide acrylique), la pectine, la carragénane, l'alginate et le poly(styrènesulfonate). The anionic polymer can be chosen from poly (acrylic acid), pectin, carrageenan, alginate and poly (styrenesulfonate).
Le mélange de l'étape a) peut comprendre, en pourcentages massiques exprimés par rapport à la masse dudit mélange : The mixture of step a) can comprise, in percentages by mass expressed relative to the mass of said mixture:
- entre 0,2 % et 0,5 %, de préférence entre 0,28 % et 0,4 %, du polymère cationique ; - between 0.2% and 0.5%, preferably between 0.28% and 0.4%, of the cationic polymer;
- entre 0,6 % et 1,5 %, de préférence entre 0,8 % et 1,2 %, du polymère anionique. - between 0.6% and 1.5%, preferably between 0.8% and 1.2%, of the anionic polymer.
L'étape a) peut être réalisée en ajoutant progressivement la solution aqueuse de polymère cationique dans un récipient contenant la solution aqueuse de polymère anionique. Step a) can be carried out by gradually adding the aqueous solution of cationic polymer to a container containing the aqueous solution of anionic polymer.
Optionnellement, à l'étape a), on ajoute au mélange au moins un composé solide. Ce composé solide peut être choisi parmi le charbon actif, la silice et l'argile. Ce composé solide va conférer à la membrane de nouvelles fonctions réactives ou de nouvelles fonctionnalités. En effet, ces exemples de composés solides sont poreux et portent des groupements fonctionnels présentant des affinités différentes vis-à-vis des contaminants ; ce qui permet d'élargir les applications envisageables de la membrane. Par ailleurs, leurs caractéristiques poreuses et/ou polaires/apolaires peuvent lui conférer des propriétés d'immobilisation de composés organiques (par exemple des huiles essentielles, des parfums ou bien encore tout composé chimique utilisé pour les extractions liquide/liquide). Cela permet ainsi de réaliser, à partir d'une membrane obtenue avec le procédé de fabrication selon l'invention et à l'issue d'une étape d'imprégnation de molécules organiques, un support imprégné pour la diffusion contrôlée de molécules (un diffuseur de parfum par exemple) ou une membrane imprégnée qui est applicable dans les procédés d'extraction conventionnels tels que les membranes poreuses immobilisant des extractants liquides/solvants ou des liquides ioniques. Optionally, in step a), at least one solid compound is added to the mixture. This solid compound can be chosen from activated carbon, silica and clay. This solid compound will give the membrane new reactive functions or new functionalities. In fact, these examples of solid compounds are porous and carry functional groups having different affinities with respect to contaminants; which makes it possible to broaden the possible applications of the membrane. Moreover, their porous and / or polar / non-polar characteristics can give it properties of immobilization of organic compounds (for example essential oils, perfumes or even any chemical compound used for liquid / liquid extractions). This thus makes it possible to produce, from a membrane obtained with the manufacturing process according to the invention and at the end of an organic molecule impregnation step, an impregnated support for the controlled diffusion of molecules (a diffuser perfume for example) or an impregnated membrane which is applicable in conventional extraction processes such as porous membranes immobilizing liquid / solvent extractants or ionic liquids.
De préférence, le composé solide est réhydraté avant son introduction dans le mélange afin de faciliter sa dispersion dans ce mélange qui est visqueux du fait de la présence des deux polymères. Si au moins un composé solide est ajouté, cet ajout représente, en pourcentage massique exprimé par rapport à la masse sèche de la membrane entre 0,05 % et 1,2 %. Plus précisément, lorsque le composé est du charbon actif ou de la silice, le pourcentage massique peut être compris entre 0,05% et 0,4%, de préférence entre 0,1 % et 0,3 %. Lorsqu'il s'agit d'argile, le pourcentage massique peut être compris entre 0,4 % et 1,2%, de préférence entre 0,5 % et 0,8%. Preferably, the solid compound is rehydrated before its introduction into the mixture in order to facilitate its dispersion in this mixture which is viscous owing to the presence of the two polymers. If at least one solid compound is added, this addition represents, as a percentage by mass expressed relative to the dry mass of the membrane, between 0.05% and 1.2%. More precisely, when the compound is activated carbon or silica, the mass percentage can be between 0.05% and 0.4%, preferably between 0.1% and 0.3%. In the case of clay, the mass percentage can be between 0.4% and 1.2%, preferably between 0.5% and 0.8%.
L'étape b) peut être réalisée à température ambiante avec une agitation à une vitesse comprise entre 16 000 tours/minute et 22 000 tours/minute, de préférence entre 19 000 tours/minute et 21 000 tours/minute. Step b) can be carried out at room temperature with stirring at a speed of between 16,000 revolutions / minute and 22,000 revolutions / minute, preferably between 19,000 revolutions / minute and 21,000 revolutions / minute.
La durée de l'étape b) peut être comprise entre 30 secondes et 2 minutes, de préférence entre 40 secondes et 80 secondes. The duration of step b) can be between 30 seconds and 2 minutes, preferably between 40 seconds and 80 seconds.
A l'issue de l'étape b), le mélange peut être coulé dans un moule (par exemple une boîte en polypropylène) et l'étape c) de maturation est alors effectuée. La géométrie du moule va procurer une forme à la membrane qui sera obtenue à l'issue du procédé selon l'invention. Les géométries variées des moules permettent de produire des membranes de différentes formes et de différentes dimensions. At the end of step b), the mixture can be poured into a mold (for example a polypropylene box) and the maturation step c) is then carried out. The geometry of the mold will give a shape to the membrane which will be obtained at the end of the process according to the invention. The varied geometries of the molds allow the production of membranes of different shapes and sizes.
Au cours de l'étape c), il se forme au sein du mélange une membrane sous la forme d'un hydrogel du fait de l'interaction ionique entre des groupements chargés positivement du polymère cationique (par exemple les fonctions aminées de la PEI, ou d'un chitosane) et des groupements chargés négativement du polymère anionique (par exemple les fonctions carboxyliques de l'alginate ou les fonctions sulfoniques d'un carragénane). Par hydrogel, on entend selon l'étape c), un matériau formant une membrane humide et constitué d'un réseau des deux polymères cationique et anionique. Ce réseau polymère possède une structure qui ne résulte pas d'une gélification ionotropique, mais bien de liaisons ioniques entre des groupements précités de charges opposées et qui présente d'ores et déjà une macroporosité. During step c), a membrane is formed within the mixture in the form of a hydrogel due to the ionic interaction between positively charged groups of the cationic polymer (for example the amino functions of the PEI, or of a chitosan) and negatively charged groups of the anionic polymer (for example the carboxylic functions of the alginate or the sulfonic functions of a carrageenan). By hydrogel is meant according to step c), a material forming a wet membrane and consisting of a network of two cationic and anionic polymers. This polymer network has a structure which does not result from ionotropic gelation, but indeed from ionic bonds between the aforementioned groups of opposite charges and which already has macroporosity.
L'étape c) peut être réalisée sur une plage de températures variant entre -80°C et 50°C (incluant donc une congélation du mélange pour les températures négatives). Celle-ci n'est pas déterminante pour que l'interaction entre des groupements chargés positivement du polymère cationique et des groupements chargés négativement du polymère anionique ait lieu. Ainsi, elle peut être conduite à température ambiante, elle peut aussi être menée, dans un mode de réalisation de l'invention, à une température comprise entre -10°C et -30°C. Dans ce dernier mode, on obtient une membrane mécaniquement stable avec une élasticité remarquable (à savoir qu'elle peut accepter des déformations importantes). Dans le cas d'une congélation, la décongélation intervient au cours de l'étape d) au cours de laquelle on ajoute l'agent de réticulation. Step c) can be carried out over a temperature range varying between -80 ° C and 50 ° C (therefore including freezing of the mixture for negative temperatures). This is not critical for the interaction between positively charged groups of the cationic polymer and negatively charged groups of the anionic polymer to take place. Thus, it can be carried out at room temperature, it can also be carried out, in one embodiment of the invention, at a temperature between -10 ° C and -30 ° C. In this last mode, one obtains a mechanically stable membrane with a remarkable elasticity (namely that it can accept important deformations). In the case of freezing, thawing takes place during step d) during which the crosslinking agent is added.
La température de l'étape c) a cependant une influence sur la cinétique réactionnelle (ou autrement dit sur la qualité des interactions ioniques entre le polymère cationique et le polymère anionique), et en conséquence sur le processus de structuration de la membrane ; ce qui induit les caractéristiques texturales (en particulier des caractéristiques de macroporosité) de la membrane obtenue selon le procédé de fabrication selon l'invention. The temperature of step c) however has an influence on the reaction kinetics (or in other words on the quality of the ionic interactions between the cationic polymer and the anionic polymer), and consequently on the process of structuring of the membrane; which induces the textural characteristics (in particular the macroporosity characteristics) of the membrane obtained according to the manufacturing process according to the invention.
Au cours de l'étape c), avantageusement, tous les groupements chargés des polymères cationique et anionique respectivement n'interagissent pas nécessairement. En effet, des groupements libres (ou chargés suivant l'application visée) devront subsister pour l'étape d) consécutive de réticulation, selon la réticulation souhaitée, mais aussi en raison de leur implication selon l'utilisation qui est ensuite faite de la membrane issue du procédé de l'invention. Il relève bien entendu des compétences de l'homme du métier d'adapter les conditions de l'étape c) à la qualité de la membrane attendue. Ainsi, si elle est utilisée pour retenir des ions métalliques, il conviendra de s'assurer que des groupements réactifs (cationiques et anioniques des polymères de départ) restent libres. A titre d'exemple, et selon le domaine d'application d'une membrane de l'invention, on peut envisager que le taux de groupements chargés positivement et/ou de groupements chargés négativement restés libres est inférieur ou égal à 50%, par exemple de 30-50%. S'il est nécessaire de contrôler ce taux, l'homme du métier, à l'appui de ses connaissances générales, peut notamment agir sur le rapport de la concentration du polymère cationique à celle du polymère anionique, sur la durée de l'étape b). During step c), advantageously, all the charged groups of the cationic and anionic polymers respectively do not necessarily interact. Indeed, free groups (or charged depending on the intended application) will have to remain for the consecutive step d) of crosslinking, depending on the desired crosslinking, but also because of their involvement depending on the use which is then made of the membrane. resulting from the process of the invention. It is of course within the competence of those skilled in the art to adapt the conditions of step c) to the quality of the expected membrane. Thus, if it is used to retain metal ions, it will be necessary to ensure that reactive groups (cationic and anionic of the starting polymers) remain free. By way of example, and according to the field of application of a membrane of the invention, it can be envisaged that the rate of positively charged groups and / or of negatively charged groups which have remained free is less than or equal to 50%, for example example of 30-50%. If it is necessary to control this rate, a person skilled in the art, on the basis of his general knowledge, can in particular act on the ratio of the concentration of the cationic polymer to that of the anionic polymer, over the duration of the step. b).
Optionnellement, entre l'étape c) et l'étape d), on lave au moins une fois la membrane avec de l'eau, de préférence avec de l'eau déminéralisée. Cela permet d'éliminer les réactifs et monomères n'ayant pas réagi entre les différents constituants à l'étape c), ainsi que les parties labiles. Optionally, between step c) and step d), the membrane is washed at least once with water, preferably with demineralized water. This makes it possible to remove the reagents and monomers which have not reacted between the various constituents in step c), as well as the labile parts.
Au cours de l'étape d), on ajoute au moins un agent de réticulation dans le mélange qui contient la membrane sous la forme d'un hydrogel de l'étape c). Cette étape de réticulation du réseau formé à l'étape c) génère un maillage supplémentaire pour former un nouveau réseau réticulé qui contribue alors à renforcer la structuration de la membrane et en particulier à figer le réseau poreux. Ce maillage supplémentaire peut être le résultat d'une réticulation des chaînes du polymère cationique entre elles, d'une réticulation des chaînes du polymère anionique entre elles, ou d'une réticulation des chaînes du polymère cationique et des chaînes du polymère anionique, selon l'agent de réticulation impliqué, ou bien même une combinaison de ces mécanismes avec la mise en œuvre de plusieurs agents de réticulation. Il est entendu que la réticulation intervient entre les chaînes voisines. L'homme du métier est à même de sélectionner le ou les agents de réticulation pour cette étape, notamment en fonction de l'application qui est faite de la membrane à haut pouvoir de percolation fabriquée. Il convient d'observer que cette étape d) peut impliquer des groupements desdits polymères cationique et/ou anionique, qui sont aussi les groupements impliqués dans l'étape c) ; il est donc dans ce cas nécessaire que tous ces groupements n'aient pas été engagés à l'étape c). During step d), at least one crosslinking agent is added to the mixture which contains the membrane in the form of a hydrogel from step c). This step of crosslinking the network formed in step c) generates an additional mesh to form a new crosslinked network which then contributes to reinforcing the structuring of the membrane and in particular to freezing the porous network. This additional mesh can be the result of a crosslinking of the chains of the cationic polymer between them, of a crosslinking of the chains of the anionic polymer between them, or of a crosslinking of the chains of the cationic polymer and of the chains of the anionic polymer, according to the crosslinking agent involved, or even a combination of these mechanisms with the use of several crosslinking agents. It is understood that the crosslinking takes place between the neighboring chains. Those skilled in the art are able to select the crosslinking agent (s) for this step, in particular as a function of the application which is made of the high percolation membrane manufactured. It should be observed that this step d) can involve groups of said cationic and / or anionic polymers, which are also the groups involved in step c); it is therefore in this case necessary that all these groups have not been engaged in step c).
Ainsi pour réticuler les chaînes du polymère cationique entre elles, l'agent de réticulation est choisi de manière appropriée en fonction de la nature du polymère cationique. L'agent de réticulation peut être le glutaraldéhyde. Thus, in order to crosslink the chains of the cationic polymer to one another, the crosslinking agent is suitably chosen according to the nature of the cationic polymer. The crosslinking agent can be glutaraldehyde.
Par exemple, lorsque le polymère cationique est la PEI, lors de l'ajout du glutaraldéhyde, la fonction aldéhyde de ce dernier va réagir avec les fonctions aminées libres de la PEI. Il s'agit d'une réaction de type base de Schiff. For example, when the cationic polymer is PEI, during the addition of glutaraldehyde, the aldehyde function of the latter will react with the free amino functions of the PEI. This is a Schiff base type reaction.
Le pourcentage massique de l'agent de réticulation peut être compris entre 0,1 % et 1 %, par rapport à la masse du mélange de l'étape a). Lorsque le mélange comprend des composés solides tels que décrits ci-dessus, le pourcentage massique de l'agent de réticulation est avantageusement compris entre 0,1% et 0,6%. The percentage by weight of the crosslinking agent can be between 0.1% and 1%, relative to the weight of the mixture from step a). When the mixture comprises solid compounds as described above, the percentage by weight of the crosslinking agent is advantageously between 0.1% and 0.6%.
A l'étape d), l'agent de réticulation est avantageusement ajouté au mélange sous agitation lente (par exemple en soumettant le mélange à un mouvement de « va-et-vient » : entre 20 et 40 mouvements par minute). In step d), the crosslinking agent is advantageously added to the mixture with slow stirring (for example by subjecting the mixture to a “back and forth” movement: between 20 and 40 movements per minute).
Optionnellement, entre l'étape d) et l'étape e), on lave au moins une fois la membrane réticulée avec de l'eau, de préférence avec de l'eau déminéralisée. Cela permet d'éliminer les réactifs et monomères n'ayant pas réagi entre les différents constituants, ainsi que les parties labiles. Optionally, between step d) and step e), the crosslinked membrane is washed at least once with water, preferably with demineralized water. This makes it possible to eliminate the reagents and monomers which have not reacted between the various constituents, as well as the labile parts.
A l'étape e), on sèche la membrane ainsi obtenue. Le séchage est avantageusement réalisé à température ambiante sous flux d'air (par exemple avec une hotte aspirante). Ce processus ne nécessite pas de dispositif complexe et énergivore ; ce qui fait l'originalité et l'intérêt du procédé selon l'invention. On obtient alors une membrane macro-poreuse et homogène. In step e), the membrane thus obtained is dried. The drying is advantageously carried out at ambient temperature under an air flow (for example with an extractor hood). This process does not require a complex and energy-consuming device; which makes the originality and the interest of the process according to the invention. This gives a macro-porous and homogeneous membrane.
Toutefois, il peut être envisagé, si les applications de la membrane le nécessitent, d'effectuer un séchage plus sophistiqué (par exemple par lyophilisation ou dans des conditions de CO2 supercritique) de manière à obtenir une membrane présentant une structure macroporeuse et dont la surface est micro- ou méso-poreuse. L'ensemble des étapes du procédé de fabrication peuvent être toutes mises en œuvre à une température comprise entre 4°C et 50°C, de préférence à une température ambiante (à savoir comprise entre 15°C et 25°C) de manière à obtenir une membrane homogène et macro-poreuse. However, it can be envisaged, if the applications of the membrane so require, to carry out a more sophisticated drying (for example by lyophilization or under supercritical CO2 conditions) so as to obtain a membrane having a macroporous structure and whose surface is micro- or mesoporous. All the steps of the manufacturing process can all be implemented at a temperature between 4 ° C and 50 ° C, preferably at an ambient temperature (namely between 15 ° C and 25 ° C) so as to obtain a homogeneous and macro-porous membrane.
A l'issue du procédé de fabrication selon l'invention, on obtient une membrane qui présente les propriétés suivantes : At the end of the manufacturing process according to the invention, a membrane is obtained which has the following properties:
- une densité apparente comprise entre 0,02 g/cm3 et 0,1 g/cm3 , de préférence d'environ 0,04 g/cm3 ; - an apparent density of between 0.02 g / cm 3 and 0.1 g / cm 3 , preferably about 0.04 g / cm 3 ;
- une porosité telle que le pourcentage de vide est compris entre 90% et 96%, de préférence d'environ 95% ; a porosity such that the percentage of void is between 90% and 96%, preferably around 95%;
- un flux d'eau par percolation naturelle (à savoir sans pression) compris entre 40 et 200 mL/cm2.min, de préférence d'environ 146 mL/cm2.min ; soit une vitesse superficielle comprise entre 24 et 120 mL/cm2.min, de préférence d'environ 87 m/h. - a flow of water by natural percolation (namely without pressure) of between 40 and 200 mL / cm 2 .min, preferably of about 146 mL / cm 2 .min; or a surface speed of between 24 and 120 mL / cm 2 .min, preferably about 87 m / h.
Ainsi, à la différence des membranes de l'art antérieur, le procédé de fabrication selon l'invention présente l'avantage de ne nécessiter aucun processus de séchage sophistiqué pour maintenir la haute porosité de la membrane. Le procédé selon l'invention fait appel à des étapes simples d'agitation, gélification et réticulation, ainsi que de séchage à température ambiante. Il ne nécessite pas obligatoirement d'étape de lyophilisation ou de production d'un cryogel. Thus, unlike the membranes of the prior art, the manufacturing process according to the invention has the advantage of not requiring any sophisticated drying process to maintain the high porosity of the membrane. The process according to the invention makes use of simple steps of agitation, gelation and crosslinking, as well as of drying at room temperature. It does not necessarily require a freeze-drying step or the production of a cryogel.
L'étape de séchage sophistiqué tel que décrite ci-dessus est parfaitement optionnelle dans le cadre de l'invention et n'est en mise en œuvre que si l'on souhaite disposer d'une membrane présentant une bi-structure, à savoir une structure macroporeuse et dont la surface est micro- ou meso-poreuse. The sophisticated drying step as described above is perfectly optional in the context of the invention and is implemented only if it is desired to have a membrane having a bi-structure, namely a macroporous structure with a micro- or meso-porous surface.
Par ailleurs, le procédé de fabrication selon l'invention présente l'avantage d'obtenir une membrane mécaniquement stable avec une bonne élasticité, en particulier lorsqu'à l'étape c) on laisse maturer le mélange en le congélant. Furthermore, the manufacturing process according to the invention has the advantage of obtaining a mechanically stable membrane with good elasticity, in particular when, in step c), the mixture is allowed to mature by freezing it.
Le procédé selon l'invention permet la fabrication aisée de membranes dans de meilleures conditions énergétiques. The method according to the invention allows the easy manufacture of membranes under better energy conditions.
L'invention concerne aussi une membrane à haut pouvoir de percolation susceptible d'être obtenue par le procédé ci-dessus, en particulier telle qu'obtenue par ce procédé. Selon les applications dans lesquelles elle est employée et donc le procédé de fabrication retenu dans ce but, elle peut être une membrane adsorbante, elle peut aussi être une membrane n'impliquant pas d'interaction de ses groupements. The invention also relates to a membrane with high percolation power capable of being obtained by the above process, in particular as obtained by this process. Depending on the applications in which it is used and therefore the manufacturing method adopted for this purpose, it can be an adsorbent membrane, it can also be a membrane not involving any interaction of its groups.
L'invention a aussi pour objet l'utilisation de la membrane obtenue selon le procédé de fabrication pour le traitement d'effluents liquides ou gazeux. L'invention a aussi pour objet l'utilisation de la membrane obtenue selon le procédé de fabrication en tant que support pour la catalyse hétérogène. Ce support présente l'avantage de pouvoir récupérer facilement les catalyseurs en fin de cycle de vie grâce à une élimination aisée de la membrane, par exemple par dégradation thermique. Cela permet ainsi le recyclage des métaux précieux qui sont utilisés comme catalyseur pour la catalyse hétérogène. A subject of the invention is also the use of the membrane obtained according to the manufacturing process for the treatment of liquid or gaseous effluents. A subject of the invention is also the use of the membrane obtained according to the manufacturing process as a support for heterogeneous catalysis. This support has the advantage of being able to easily recover the catalysts at the end of their life cycle thanks to easy removal from the membrane, for example by thermal degradation. This thus allows the recycling of precious metals which are used as catalyst for heterogeneous catalysis.
L'invention a aussi pour objet l'utilisation de la membrane obtenue selon le procédé de fabrication en tant que support anti-microbiens. En effet, la membrane peut aisément retenir des composés anti-microbiens tels que des cations métalliques (par exemple Ag(l), Zn(ll), Cu(ll), Ni(ll)) qui ont des propriétés biocides. A subject of the invention is also the use of the membrane obtained according to the manufacturing process as an anti-microbial support. Indeed, the membrane can easily retain anti-microbial compounds such as metal cations (for example Ag (l), Zn (II), Cu (II), Ni (II)) which have biocidal properties.
Par ailleurs, la membrane peut également présenter des propriétés anti microbiennes si elle est modifiée chimiquement par le greffage d'amines quaternaires, par exemple au niveau du polymère cationique. Cette modification chimique peut avoir été effectuée sur le polymère cationique avant la mise en œuvre du procédé de fabrication selon l'invention ou bien avant ou après l'étape de séchage. Le greffage d'amines quaternaires est parfaitement à la portée de l'homme du métier, tout comme ces propriétés antimicrobiennes obtenues grâce à la quaternisation de polymères cationiques. Furthermore, the membrane can also exhibit antimicrobial properties if it is chemically modified by the grafting of quaternary amines, for example at the level of the cationic polymer. This chemical modification may have been carried out on the cationic polymer before the implementation of the manufacturing process according to the invention or even before or after the drying step. The grafting of quaternary amines is perfectly within the reach of a person skilled in the art, as are these antimicrobial properties obtained by the quaternization of cationic polymers.
La membrane obtenue avec le procédé selon l'invention sur laquelle ont été adsorbés des cations métalliques ou qui a été modifiée chimiquement par une quaternisation de telle sorte qu'elle présente des propriétés biocides peut ainsi être utilisée en tant que média filtrant pour la décontamination microbienne. The membrane obtained with the process according to the invention on which metal cations have been adsorbed or which has been chemically modified by quaternization so that it has biocidal properties can thus be used as a filter medium for microbial decontamination. .
L'invention sera mieux comprise à l'aide de la description détaillée d'expérimentations qui sont exposées ci-dessous en référence au dessin annexé représentant des résultats de données expérimentales relatives au procédé de fabrication selon l'invention. The invention will be better understood with the aid of the detailed description of experiments which are set out below with reference to the appended drawing showing results of experimental data relating to the manufacturing process according to the invention.
DESCRIPTION DES FIGURES DESCRIPTION OF FIGURES
[FIG. 1] représente un graphique des évolutions de la capacité de fixation notée « qeq » du chrome(VI) (ci-après abrégé « Cr(VI) » et du chrome total (ci-après « Cr(total ») en fonction de respectivement la concentration résiduelle Ceq en Cr(VI) et Cr(total) après des expérimentations d'adsorption d'ions de chrome sur une membrane obtenue selon une lère forme de réalisation du procédé de fabrication selon l'invention. [FIG. 1] shows a graph of the changes in the binding capacity noted "q eq " of chromium (VI) (hereinafter abbreviated "Cr (VI)" and of total chromium (hereinafter "Cr (total") as a function of respectively the residual concentration C eq in Cr (VI) and Cr (total) after experiments of adsorption of chromium ions on a membrane obtained according to a 1 st embodiment of the manufacturing process according to the invention.
[FIG. 2] représente une photographie d'une membrane obtenue selon une 2ème forme de réalisation du procédé de fabrication selon l'invention. [FIG. 3] est un graphique représentant les évolutions en fonction du temps de réaction d'hydrogénation du 3-nitrophénol (ci-après abrégé « 3-NP ») de la concentration résiduelle relative en palladium notée « Ct/Co » pour 3 membranes d'épaisseurs différentes et qui ont été obtenues selon cette 2ème forme de réalisation du procédé de fabrication selon l'invention. [FIG. 2] represents a photograph of a membrane obtained according to a 2 nd embodiment of the manufacturing method according to the invention. [FIG. 3] is a graph showing the changes as a function of the hydrogenation reaction time of 3-nitrophenol (hereinafter abbreviated "3-NP") of the relative residual concentration of palladium noted "C t / Co" for 3 membranes d 'different thicknesses and which were obtained according to this 2 nd embodiment of the manufacturing process according to the invention.
[FIG. 4] est un graphique de la modélisation des profils cinétiques par l'équation de pseudo premier ordre (ln(Ct/Co) en fonction du temps réactionnel établi à partir des concentrations résiduelles relatives en palladium relevées. [FIG. 4] is a graph of the modeling of the kinetic profiles by the pseudo first order equation (ln (Ct / Co) as a function of the reaction time established from the relative residual concentrations of palladium recorded.
[FIG. 5] représente un graphique des courbes de percée obtenues avec d'autres expérimentations de réaction d'hydrogénation du 3-NP. [FIG. 5] represents a graph of the breakthrough curves obtained with other experiments on the hydrogenation reaction of 3-NP.
[FIG. 6] représente une microphotographie d'une membrane produite selon l'invention illustrant la macroporosité du matériau (microscope électronique à balayage). [FIG. 6] shows a photomicrograph of a membrane produced according to the invention illustrating the macroporosity of the material (scanning electron microscope).
[FIG. 7] représente une photographie illustrant le haut pouvoir de percolation (par drainage gravitaire) d'une membrane produite selon l'invention lors de l'écoulement d'un liquide. [FIG. 7] represents a photograph illustrating the high percolation power (by gravity drainage) of a membrane produced according to the invention during the flow of a liquid.
[FIG. 8] représente une photographie d'une membrane produite selon l'invention (plaque, 20 x 10 cm). [FIG. 8] shows a photograph of a membrane produced according to the invention (plate, 20 x 10 cm).
[FIG. 9] représente une photographie de la macroporosité interne des membranes produites selon l'invention (en coupe, après découpe à l'emporte-pièce). [FIG. 9] represents a photograph of the internal macroporosity of the membranes produced according to the invention (in section, after cutting with a punch).
PARTIE EXPERIMENTALE EXPERIMENTAL PART
15 g d'une solution de PEI à une teneur massique de 50 % ont été dilués dans 250 g d'eau déminéralisée. Le pH de cette solution a été ajusté à une valeur de 6,5 avec de l'acide nitrique. Une solution aqueuse de PEI à une teneur massique de 3% a ainsi été obtenue. 15 g of a solution of PEI at a mass content of 50% were diluted in 250 g of demineralized water. The pH of this solution was adjusted to a value of 6.5 with nitric acid. An aqueous solution of PEI at a mass content of 3% was thus obtained.
40 g d'alginate ont été dilués avec 960 g d'eau déminéralisée de manière à obtenir une solution aqueuse d'alginate à une teneur massique de 4%. 40 g of alginate were diluted with 960 g of demineralized water so as to obtain an aqueous solution of alginate at a mass content of 4%.
132 g de la solution d'alginate ainsi obtenue ont été mélangés avec 368 g d'eau déminéralisée. 132 g of the alginate solution thus obtained were mixed with 368 g of deionized water.
On a agité, puis on a ajouté 35 mL de la solution de PEI (à savoir 5 mLtoutes les 10 secondes, cette opération ayant été répétée 7 fois). Stirred, then 35 mL of the PEI solution was added (i.e. 5 mL every 10 seconds, which was repeated 7 times).
Le mélange a été agité pendant une minute. Le mélange a été versé dans une boîte en polypropylène en évitant la formation de bulles et l'ensemble a été laissé à température ambiante pendant 24 heures. Une membrane a été obtenue par la réaction de gélification de l'alginate avec la PEI. The mixture was stirred for one minute. The mixture was poured into a polypropylene box avoiding the formation of bubbles and the whole was left at room temperature for 24 hours. A membrane was obtained by the gelation reaction of alginate with PEI.
La membrane a été lavée 5 fois avec de l'eau déminéralisée. The membrane was washed 5 times with deionized water.
La membrane lavée a été mise en suspension dans 300 mL d'eau déminéralisée auquel on a rajouté 4 mL d'une solution aqueuse de glutaraldéhyde à une teneur massique de 50% de manière à effectuer la réticulation de la membrane. The washed membrane was suspended in 300 mL of demineralized water to which was added 4 mL of an aqueous solution of glutaraldehyde at a mass content of 50% so as to effect crosslinking of the membrane.
Ensuite, on a soumis la membrane à une agitation modérée de 30 mouvements de « va-et-vient » par minute pendant 24 heures. Then, the membrane was subjected to moderate agitation of 30 "back and forth" movements per minute for 24 hours.
La membrane a été rincée (6 fois) avec 300 mL d'eau déminéralisée, puis séchée à température ambiante pendant 2 jours. The membrane was rinsed (6 times) with 300 mL of deionized water, then dried at room temperature for 2 days.
Caractérisations de la membrane obtenue : Characterizations of the membrane obtained:
La membrane ainsi obtenue présentait les caractéristiques suivantes : une porosité (mesurée avec un pycnomètre) de 93,4 % ; une stabilité de 94 % à l'attrition; The membrane thus obtained exhibited the following characteristics: a porosity (measured with a pycnometer) of 93.4%; 94% stability to attrition;
un flux d'eau (en percolation naturelle) de 33,6 mL/(cm2.min) ; a water flow (in natural percolation) of 33.6 mL / (cm 2 .min);
un pH à point de charge zéro (ci-après abrégé « pHpzc ») de 5,7. a zero charge point pH (hereinafter abbreviated "pHpzc") of 5.7.
La valeur de 93,4% témoigne d'une forte porosité de la membrane qui est tout à fait appropriée pour assurer de bonnes performances de percolation naturelle, et ce comme en atteste le flux de filtration (vitesse superficielle de filtration de l'ordre de 20 m/h). The value of 93.4% testifies to a high porosity of the membrane which is quite suitable for ensuring good natural percolation performance, as evidenced by the filtration flow (filtration surface speed of the order of 20 m / h).
La stabilité de la membrane a été déterminée en soumettant à une agitation de 150 tours/min pendant 72 heures un échantillon de la membrane sous la forme d'un disque de diamètre 25 mm immergé dans 20 mL d'eau. Puis, la membrane a été séchée et pesée. La stabilité est le pourcentage de membrane restante à l'issue de cette agitation par rapport à la masse initiale de membrane. La valeur de 94 % témoigne d'une très bonne stabilité à l'attrition de la membrane et du maintien de son intégrité lorsqu'elle est soumise à une forte agitation dans l'eau. The stability of the membrane was determined by subjecting a sample of the membrane in the form of a 25 mm diameter disc immersed in 20 mL of water to stirring at 150 rpm for 72 hours. Then, the membrane was dried and weighed. Stability is the percentage of membrane remaining at the end of this agitation relative to the initial mass of membrane. The value of 94% testifies to a very good stability to attrition of the membrane and to the maintenance of its integrity when it is subjected to strong agitation in water.
Le flux d'eau a été déterminé en mesurant le temps nécessaire pour le passage de 100 mL d'eau au travers un échantillon de membrane d'une surface de 4,64 cm2, et ce à 20°C et à une pression de 0,006 bar. La valeur du flux d'eau (en percolation naturelle) de 33,6 mL/(cm2.min) témoigne d'excellentes propriétés de percolation de la membrane. La figure 7 illustre l'écoulement naturel par drainage gravitaire au travers de la macroporosité des membranes à haut pouvoir de percolation. En outre, la membrane ainsi obtenue a été soumise à des expérimentations de sorption avec une solution contenant des ions de Cr(VI) afin de caractériser ses propriétés d'adsorption. The water flow was determined by measuring the time required for 100 mL of water to pass through a membrane sample with an area of 4.64 cm 2 , at 20 ° C and a pressure of 0.006 bar. The value of the water flow (in natural percolation) of 33.6 mL / (cm 2 .min) testifies to the excellent percolation properties of the membrane. FIG. 7 illustrates the natural flow by gravity drainage through the macroporosity of membranes with high percolation power. In addition, the membrane thus obtained was subjected to sorption experiments with a solution containing Cr (VI) ions in order to characterize its adsorption properties.
Pour ce faire, le dispositif utilisé pour ces expérimentations consistait en un dispositif fonctionnant en continu pour la recirculation de solutions contenant des ions métalliques qui comprenait : To do this, the device used for these experiments consisted of a device operating continuously for the recirculation of solutions containing metal ions which included:
- une pompe péristaltique commercialisée par la société Ismatec sous la dénomination commerciale ISM404B ; a peristaltic pump marketed by the company Ismatec under the trade name ISM404B;
- un support configuré pour contenir la membrane et permettre la circulation de la solution d'ions métalliques au travers de ladite membrane ; - a support configured to contain the membrane and allow the circulation of the metal ion solution through said membrane;
- un réservoir contenant la solution d'ions métalliques équipé d'un agitateur magnétique commercialisé par la société Thermo Scientific sous la dénomination commerciale Variomag® Poly 15 pour agiter la solution ; - a tank containing the metal ion solution with a magnetic stirrer sold by Thermo Scientific under the trade name Poly Variomag ® 15 for agitating the solution;
- un dispositif pour la circulation en boucle de la solution d'ions métalliques et son passage au travers de la membrane. - a device for the loop circulation of the metal ion solution and its passage through the membrane.
Au cours de ces expérimentations, la solution d'ions Cr(VI) a été mise en circulation en boucle dans le dispositif avec une vitesse de pompage de 15 ou 30 m L/minute. During these experiments, the solution of Cr (VI) ions was circulated in a loop in the device with a pumping speed of 15 or 30 m L / minute.
Au cours de ces expérimentations, des ions Cr(lll) sont apparus par réduction in situ sur la membrane des ions Cr(VI). During these experiments, Cr (III) ions appeared by reduction in situ on the membrane of Cr (VI) ions.
La concentration en Cr(VI) a été déterminée avec un spectrophotomètre par ultra-violets commercialisé par la société Shimadzu sous la dénomination commerciale UV-1650PC à une longueur d'onde de 540 nm par la méthode colorimétrique à la diphénylcarbazone. The Cr (VI) concentration was determined with an ultraviolet spectrophotometer sold by the company Shimadzu under the trade name UV-1650PC at a wavelength of 540 nm by the colorimetric method using diphenylcarbazone.
La concentration totale en Cr (à savoir la somme des ions Cr(VI) et Cr(lll)) a été déterminée par spectrométrie d'émission atomique avec plasma induit avec un spectromètre commercialisé par la société Horiba sous la dénomination commerciale Activa. The total Cr concentration (ie the sum of the Cr (VI) and Cr (III) ions) was determined by atomic emission spectrometry with induced plasma with a spectrometer sold by the company Horiba under the trade name Activa.
La concentration en Cr(lll) a été déterminée par soustraction à la concentration en Cr(total) de la concentration en Cr(VI). The concentration of Cr (III) was determined by subtracting the concentration of Cr (total) from the concentration of Cr (VI).
La membrane a aussi été caractérisée par : The membrane was also characterized by:
microscopie électronique à balayage avec un microscope commercialisé par la société Thermo Fisher Scientific sous la dénomination commerciale Quanta™ FEG 200, de manière à démontrer la haute porosité de la membrane ; scanning electron microscopy with a microscope sold by Thermo Fisher Scientific under the trade name Quanta ™ FEG 200, so as to demonstrate the high porosity of the membrane;
analyse dispersive en énergie de manière à montrer la distribution dense et homogène d'ions métalliques (chrome) au sein de la membrane. Photographies par microscopie électronique à balayage : energy dispersive analysis to show the dense and homogeneous distribution of metal ions (chromium) within the membrane. Photographs by scanning electron microscopy:
Les photographies prises par microscopie électronique à balayage ont montré que la structure de la membrane ainsi obtenue à l'issue du procédé de fabrication selon l'invention était poreuse. Plus précisément, la porosité observée était irrégulière en termes de géométrie de cellule mais régulièrement distribuée dans l'espace et en termes de taille moyenne dont l'ordre de grandeur était entre 100 et 200 pm. Ceci est illustré à la figure 6. The photographs taken by scanning electron microscopy have shown that the structure of the membrane thus obtained at the end of the manufacturing process according to the invention was porous. More precisely, the porosity observed was irregular in terms of cell geometry but regularly distributed in space and in terms of average size whose order of magnitude was between 100 and 200 μm. This is illustrated in Figure 6.
Après que la membrane (un échantillon de 30 mg) a été soumise à une sorption de Cr(VI) à l'issue d'une recirculation dans le dispositif d'expérimentation tel que détaillé ci-dessus avec une solution aqueuse qui contenait des ions Cr(VI) à une concentration de 200 mg/L à un pH de 2 pendant une durée de 96 heures avec un débit d'alimentation en recirculation de 15 mL/minute et à une température de 20°C, les photographies prises par microscopie électronique à balayage ont montré que la structure de la membrane était légèrement plus compacte et toujours poreuse. Cette compression de la membrane peut s'expliquer par le flux de liquide qui a traversé la membrane et également par la réaction du Cr(VI) avec les groupements fonctionnels de la membrane durant son adsorption sur la membrane de telle sorte que des ions Cr(lll) se sont formés in situ. La réduction partielle du Cr(VI) in situ peut en effet contribuer à modifier la structure apparente de la membrane en provoquant son oxydation. After the membrane (a sample of 30 mg) was subjected to Cr (VI) sorption following recirculation in the experiment device as detailed above with an aqueous solution which contained ions Cr (VI) at a concentration of 200 mg / L at a pH of 2 for a period of 96 hours with a recirculating feed rate of 15 mL / minute and at a temperature of 20 ° C, photographs taken by microscopy Scanning electronics showed that the membrane structure was slightly more compact and still porous. This compression of the membrane can be explained by the flow of liquid which has passed through the membrane and also by the reaction of Cr (VI) with the functional groups of the membrane during its adsorption on the membrane such that Cr ( lll) were formed in situ. The partial reduction of Cr (VI) in situ can in fact contribute to modify the apparent structure of the membrane by causing its oxidation.
Spectre d'analyse dispersive en énergie : Energy dispersive analysis spectrum:
Le spectre d'analyse dispersive en énergie après cette expérimentation de sorption a montré la présence homogène d'ions de chrome à la surface de la membrane. Cela confirme les propriétés adsorbantes de la membrane obtenue avec le procédé de fabrication selon l'invention. The energy dispersive analysis spectrum after this sorption experiment showed the homogeneous presence of chromium ions on the surface of the membrane. This confirms the adsorbent properties of the membrane obtained with the manufacturing process according to the invention.
Isotherme d'adsorption (à température ambiante) du Cr(VI) par la membrane Isothermal adsorption (at room temperature) of Cr (VI) by the membrane
L'isotherme d'adsorption a été déterminé avec le dispositif décrit ci-dessus en faisant circuler en boucle à 20°C et en continu pendant 96 heures 50 mL de solutions de Cr(VI) à un pH de 2 et à des concentrations initiales comprises entre 20 et 300 mg/L. Le débit de circulation était de 15 mL/minute. The adsorption isotherm was determined with the device described above by circulating in a loop at 20 ° C and continuously for 96 hours 50 mL of Cr (VI) solutions at a pH of 2 and at initial concentrations. between 20 and 300 mg / L. The circulation rate was 15 mL / minute.
Lorsque l'équilibre était atteint, le filtrat recueilli à l'issue de l'expérimentation était analysé afin de déterminer: When equilibrium was reached, the filtrate collected at the end of the experiment was analyzed in order to determine:
- la concentration résiduelle Ceq en Cr(VI) et - the residual concentration C eq in Cr (VI) and
- la concentration résiduelle Ceq en Cr(total), - the residual concentration C eq in Cr (total),
avec les techniques telles que détaillées ci-dessus. Par bilan de matière, on en a déduit les quantités de Cr(VI) et de Cr(total) qui ont été fixées sur la membrane, ainsi que les capacités de fixation correspondanteswith the techniques as detailed above. By material balance, we deduced the quantities of Cr (VI) and Cr (total) which were fixed on the membrane, as well as the corresponding fixing capacities.
(Peq)· (Peq)
La figure 1 est un graphique des évolutions de la capacité de fixation qeq du Cr(VI) et du Cr(total) en fonction de respectivement la concentration résiduelle Ceq en Cr(VI) et Cr(total). Ces tracés permettent d'obtenir les isothermes d'adsorption du Cr(VI) et du Cr(total) et d'en déduire les capacités maximales d'adsorption (qmax) du Cr(VI) et du Cr(total), ainsi que l'affinité de l'adsorbant pour le soluté (adsorbat) qui est proportionnel à la pente à l'origine de la courbe. FIG. 1 is a graph of the changes in the binding capacity q eq of Cr (VI) and of Cr (total) as a function of the residual concentration C eq in Cr (VI) and Cr (total) respectively. These plots make it possible to obtain the adsorption isotherms of Cr (VI) and Cr (total) and to deduce from them the maximum adsorption capacities (q ma x) of Cr (VI) and Cr (total), as well as the affinity of the adsorbent for the solute (adsorbate) which is proportional to the slope at the origin of the curve.
Au vu de la figure 1, la capacité maximale d'adsorption excède 300 mg de Cr(VI)/g. Cette capacité maximale de fixation est très élevée (représentant plus de 6 mmol Cr(VI)/g d'adsorbant). La pente à l'origine pour le Cr(VI) est quasiment verticale. Cela démontre la forte affinité de la membrane obtenue avec le procédé de fabrication selon l'invention pour les ions chromate. La pente à l'origine pour le Cr(total) est plus faible. Cela est lié à des mécanismes de réduction in situ du Cr(VI) sur la membrane en milieu acide. In view of Figure 1, the maximum adsorption capacity exceeds 300 mg Cr (VI) / g. This maximum binding capacity is very high (representing more than 6 mmol Cr (VI) / g of adsorbent). The slope at the origin for Cr (VI) is almost vertical. This demonstrates the strong affinity of the membrane obtained with the manufacturing process according to the invention for chromate ions. The slope at the origin for Cr (total) is lower. This is linked to mechanisms of in situ reduction of Cr (VI) on the membrane in an acidic medium.
Ainsi, ces expérimentations d'adsorption du chrome par une membrane obtenue selon le procédé de fabrication selon l'invention témoignent de ses excellentes propriétés adsorbantes et donc de son potentiel pour son utilisation dans le traitement d'effluents liquides qui contiennent notamment des ions Cr(VI). série d'expérimentations : Thus, these chromium adsorption experiments by a membrane obtained according to the manufacturing process according to the invention testify to its excellent adsorbent properties and therefore to its potential for its use in the treatment of liquid effluents which contain in particular Cr ions ( VI). series of experiments:
Un volume de 100 mL d'une solution d'alginate à 4 % (en masse) a été dilué avec 400 mL d'eau déminéralisée de manière à obtenir une lère solution. A volume of 100 mL of a 4% alginate solution (by mass) was diluted with 400 mL of demineralized water so as to obtain a 1st solution.
Un volume de 35 mL d'une solution de PEI à 4 % (en masse) dont le pH a été ajusté à 6,5 avec de l'acide nitrique a été ajouté progressivement sous agitation à la lère solution (à savoir 5 mL toutes les 10 secondes, cette opération ayant été répétée 7 fois). A volume of 35 mL of a 4% (by mass) PEI solution, the pH of which was adjusted to 6.5 with nitric acid, was gradually added with stirring to the 1st solution (i.e. 5 mL every 10 seconds, this operation having been repeated 7 times).
A la fin de l'ajout de PEI, le mélange a été versé dans un moule en polypropylène en évitant la formation de bulles et l'ensemble a été laissé à température ambiante pendant 24 heures. Une membrane a été obtenue du fait de la réaction de gélification de l'alginate avec la PEI. At the end of the addition of PEI, the mixture was poured into a polypropylene mold avoiding the formation of bubbles and the whole was left at room temperature for 24 hours. A membrane was obtained due to the gelation reaction of the alginate with the PEI.
La membrane obtenue a été lavée 5 fois avec de l'eau déminéralisée afin d'éliminer les réactifs libres. 300 mL d'eau déminéralisée ont été ajoutés à la membrane lavée, puis 2,5 mL d'une solution aqueuse de glutaraldéhyde à une teneur massique de 50% de manière à renforcer la réticulation de la membrane. The membrane obtained was washed 5 times with demineralized water in order to remove the free reactants. 300 mL of demineralized water were added to the washed membrane, then 2.5 mL of an aqueous solution of glutaraldehyde at a mass content of 50% so as to reinforce the crosslinking of the membrane.
Ensuite, la membrane a été soumise une agitation modérée consistant en un mouvement de « va-et-vient » de 30 mouvements/minute pendant 24 heures. Then the membrane was subjected to moderate agitation consisting of a "back and forth" motion of 30 strokes / minute for 24 hours.
La membrane a été lavée 4 fois avec de l'eau déminéralisée, puis séchée à température ambiante pendant 2 jours. The membrane was washed 4 times with deionized water, then dried at room temperature for 2 days.
Caractérisations de la membrane obtenue : Characterizations of the membrane obtained:
La membrane ainsi obtenue présentait les caractéristiques suivantes : une porosité (mesurée avec un pycnomètre) de 70,93 % ; The membrane thus obtained exhibited the following characteristics: a porosity (measured with a pycnometer) of 70.93%;
une stabilité de 97,0% à l'attrition ; a stability of 97.0% to attrition;
un flux d'eau de 24,8 mL/(cm2. min) ; a water flow of 24.8 mL / (cm 2. min);
un pHpzcde 6,29 ; a pH of 6.29;
une densité de 0,0637 g/cm3 (ce qui révèle une forte macroporosité de la membrane). a density of 0.0637 g / cm 3 (which reveals a high macroporosity of the membrane).
La stabilité a été déterminée de la même manière que pour la lère série d'expérimentations. La valeur de 97% témoigne d'une très bonne stabilité à l'attrition de la membrane et du maintien de son intégrité lorsqu'elle est soumise à une forte agitation dans l'eau. Stability was determined in the same way as for the 1st set of experiments. The value of 97% testifies to a very good stability to attrition of the membrane and to the maintenance of its integrity when it is subjected to strong agitation in water.
Le flux d'eau été déterminé de la même manière que pour la lère série d'expérimentations. La valeur de 24,8 mL/(cm2.min) témoigne d'excellentes propriétés de percolation de la membrane. The water flow was determined in the same way as for the 1 st series of experiments. The value of 24.8 mL / (cm 2 .min) shows excellent percolation properties of the membrane.
La figure 2 représente une photographie d'un échantillon de cette membrane adsorbante 1 qui a ainsi été obtenue. L'échantillon mesure 55 mm de longueur et a un diamètre de 25 mm. FIG. 2 represents a photograph of a sample of this adsorbent membrane 1 which was thus obtained. The sample is 55 mm in length and has a diameter of 25 mm.
Utilisation de la membrane en tant que support de catalyse pour l'hydrogénation du 3- nitrophénol catalysée par du palladium Use of the membrane as a catalyst support for the hydrogenation of 3-nitrophenol catalyzed by palladium
Immobilisation du Pd(ll) : Immobilization of Pd (ll):
La membrane a été découpée en disques de diamètre 25 mm. The membrane was cut into 25 mm diameter disks.
Un disque (de masse sèche 250 mg) a ensuite été disposé dans le support configuré pour contenir la membrane du dispositif décrit dans la lère série d'expérimentations de manière à réaliser une colonne à lit fixé. Un litre d'une solution de Palladium(ll) (ci-après abrégé : « Pd(ll) ») de concentration variable, comprise entre 10 et 50 mg/L, dont le pH a été ajusté à 1 avec de l'acide sulfurique a été mis en circulation en boucle au sein de ce dispositif pendant 24 heures avec un débit de 30 mL/min. Les conditions optimales de la fixation du palladium sur la membrane (autrement dit « le meilleur rendement d'utilisation maximale du palladium ») ont été obtenues lorsque sa concentration était de 28 mg Pd/L. A disc (of dry mass 250 mg) was then placed in the support configured to contain the membrane of the device described in the 1st series of experiments so as to produce a fixed bed column. One liter of a solution of Palladium (II) (hereinafter abbreviated: "Pd (II)") of variable concentration, between 10 and 50 mg / L, the pH of which has been adjusted to 1 with acid sulfuric acid was circulated in a loop within this device for 24 hours with a flow rate of 30 mL / min. The optimum conditions for the binding of palladium on the membrane (in other words "the best maximum yield of use of palladium") were obtained when its concentration was 28 mg Pd / L.
Après fixation du palladium, la colonne a été rincée 4 fois avec de l'eau déminéralisée à un pH de 1. La membrane n'a pas été séchée avant de procéder à la réduction du métal. After fixation of the palladium, the column was rinsed 4 times with deionized water at a pH of 1. The membrane was not dried before proceeding with the reduction of the metal.
La capacité maximale de fixation de palladium atteinte avec la membrane au cours de ces recirculations a été de 224 mg Pd/g. Cette capacité de fixation est beaucoup plus élevée que celle des membranes connues de l'état de l'art qui sont utilisées pour les expérimentations catalytiques et qui contiennent environ 8,8 % (en masse) de palladium. The maximum palladium binding capacity reached with the membrane during these recirculations was 224 mg Pd / g. This binding capacity is much higher than that of the membranes known from the state of the art which are used for the catalytic experiments and which contain approximately 8.8% (by mass) of palladium.
Réduction du Pd(ll) en Pd(0): Reduction of Pd (ll) in Pd (0):
La réduction du Pd(ll) immobilisé sur la membrane a été réalisée par l'hydrate d'hydrazine (de formule chimique : IShH^PhO) à une concentration de 0,03 mol/L dans 200 mL d'une solution alcaline (à une concentration 0,5 mmol/L de NaOH) sous agitation à 60 °C pendant 5 heures. The reduction of the Pd (II) immobilized on the membrane was carried out by hydrazine hydrate (chemical formula: IShH ^ PhO) at a concentration of 0.03 mol / L in 200 mL of an alkaline solution (at a concentration of 0.5 mmol / L of NaOH) with stirring at 60 ° C. for 5 hours.
Un rinçage final (4 cycles successifs) a été réalisé afin d'éliminer toute trace de réactifs libres. A final rinse (4 successive cycles) was carried out in order to remove all traces of free reagents.
Une membrane sur laquelle était adsorbé du palladium a été obtenue. Cette membrane est ci-après abrégé « la membrane catalytique ». A membrane on which palladium was adsorbed was obtained. This membrane is hereinafter abbreviated "the catalytic membrane".
Photographies par microscopie électronique à balayage et couplage avec analyse dispersive en énergie : Photographs by scanning electron microscopy and coupling with energy dispersive analysis:
Les photographies prises par microscopie électronique à balayage et l'analyse dispersive en énergie (par semi-quantification) ont montré que la structure de la membrane ainsi obtenue était macroporeuse, relativement homogène en surface et en section. The photographs taken by scanning electron microscopy and the energy dispersive analysis (by semi-quantification) showed that the structure of the membrane thus obtained was macroporous, relatively homogeneous in surface and in section.
Observation en microscopie électronique à transmission Les observations en microscopie électronique à transmission ont montré une répartition homogène des nanoparticules de palladium à la surface de la membrane après la réduction du Pd(ll) par l'hydrate d'hydrazine. Transmission electron microscopy observation Observations by transmission electron microscopy showed a homogeneous distribution of the nanoparticles of palladium on the surface of the membrane after the reduction of Pd (II) by hydrazine hydrate.
Après la réduction du métal, la taille des nanoparticules de palladium variait entre 4,5 et 10,5 nm. After reduction of the metal, the size of the palladium nanoparticles varied between 4.5 and 10.5 nm.
Test des propriétés catalytiques de la membrane catalytique Testing the catalytic properties of the catalytic membrane
Hydrogénation du 3-NP sur la membrane (avec recirculation) La procédure opératoire utilisée pour tester les propriétés catalytiques de la membrane catalytique a été mise en œuvre avec le dispositif de recirculation décrit ci-dessus dans la lère série d'expérimentations. Hydrogenation of 3-NP on the Membrane (with Recirculation) The operating procedure used to test the catalytic properties of the catalytic membrane was carried out with the recirculation device described above in the 1st series of experiments.
La membrane catalytique a été alimentée en recirculation en boucle pendant 12 minutes par 100 mL d'une solution de 3-NP à 50 mg 3-NP/L dont le pH a été ajusté à 2,84 en présence d'acide formique à une concentration de 0,2% en masse. La concentration en acide formique a été fixée en excès molaire par rapport au 3-NP (ratio molaire acide formique/3-NP de 160/1). Le débit de recirculation était de 50 mL/min. The catalytic membrane was recirculated in a loop for 12 minutes with 100 mL of a solution of 3-NP at 50 mg 3-NP / L the pH of which was adjusted to 2.84 in the presence of formic acid at a concentration of 0.2% by mass. The formic acid concentration was set in molar excess with respect to 3-NP (formic acid / 3-NP molar ratio of 160/1). The recirculation rate was 50 mL / min.
La concentration en 3-NP a été mesurée par spectrophotométrie à 332 nm. Pour ce faire, les échantillons prélevés ont été acidifiés avec 20 pL d'une solution 5 % en masse d'acide sulfurique préalablement à l'analyse de spectrophotométrie. The 3-NP concentration was measured spectrophotometrically at 332 nm. To do this, the samples taken were acidified with 20 μL of a 5% by mass solution of sulfuric acid prior to the spectrophotometric analysis.
3 expérimentations ont été réalisées avec 3 membranes catalytiques d'épaisseurs différentes : 3 experiments were carried out with 3 catalytic membranes of different thicknesses:
- lère membrane catalytique d'épaisseur 0,58 cm et de masse 175 mg sur laquelle étaient immobilisés 26,1 mg de palladium ; - the catalytic membrane era of 0.58 cm thickness and mass 175 mg were immobilized on which 26.1 mg of palladium;
- 2ème membrane catalytique d'épaisseur 0,85 cm et de masse 255 mg sur laquelle étaient immobilisés 27,2 mg de palladium ; - 2 nd catalytic membrane 0.85 cm thick and of mass 255 mg on which were immobilized 27.2 mg of palladium;
- 3ème membrane catalytique d'épaisseur 1,06 cm et de masse 313 mg sur laquelle étaient immobilisés 27,7 mg de palladium. - 3rd catalytic membrane thickness 1.06 cm, mass 313 mg, on which were immobilized 27,7 mg palladium.
La figure 3 est un graphique représentant les évolutions en fonction du temps de réaction d'hydrogénation de la concentration résiduelle relative en palladium notée « Ct/Co » pour les 3 membranes testées : FIG. 3 is a graph showing the changes as a function of the hydrogenation reaction time of the relative residual concentration of palladium noted “C t / Co” for the 3 membranes tested:
- lère courbe notée « A » pour la lère membrane catalytique ; - the era curve rated "A" for the catalytic membrane era;
- 2ème courbe notée « B » pour la 2ème membrane catalytique ; - 2 nd curve noted "B" for the 2 nd catalytic membrane;
- 3ème courbe notée « C » pour la 3ème membrane catalytique. Au vu de l'allure similaire des 3 courbes A à C, on relève que l'épaisseur de la membrane catalytique n'affecte pas le profil cinétique de la réaction d'hydrogénation du 3-NP catalysée par le palladium. - 3 rd curve denoted "C" for the 3 rd catalytic membrane. In view of the similar appearance of the 3 curves A to C, it is noted that the thickness of the catalytic membrane does not affect the kinetic profile of the hydrogenation reaction of 3-NP catalyzed by palladium.
La figure 4 est un graphique de la modélisation des profils cinétiques par l'équation de pseudo premier ordre (ln(Ct/Co) en fonction du temps réactionnel pour les 3 membranes catalytique testées : FIG. 4 is a graph of the modeling of the kinetic profiles by the pseudo first order equation (ln (Ct / Co) as a function of the reaction time for the 3 catalytic membranes tested:
- lère courbe notée « A » pour la lère membrane catalytique ; - the era curve rated "A" for the catalytic membrane era;
- 2ème courbe notée « B » pour la 2ème membrane catalytique ; - 2 nd curve noted "B" for the 2 nd catalytic membrane;
- 3ème courbe notée « C » pour la 3ème membrane catalytique. - 3 rd curve denoted "C" for the 3 rd catalytic membrane.
Cette modélisation a montré une variation limitée du coefficient cinétique d'ordre 1. En effet, ce coefficient était de : This modelization showed a limited variation of the kinetic coefficient of order 1. Indeed, this coefficient was of:
- 0,0061 s 1 pour la lère membrane catalytique ; - 0.0061 s 1 for the catalytic membrane era;
- 0,0068 s 1 pour la 2ème membrane catalytique; - 0.0068 s 1 for the 2 nd catalytic membrane;
- 0,0083 s 1 pour la 3ème membrane catalytique. - 0.0083 s 1 for the 3 rd catalytic membrane.
Ces 3 expérimentations montrent que les nanoparticules de palladium restent disponibles et le haut pouvoir de percolation des membranes obtenues avec le procédé de fabrication selon l'invention permet de maintenir une bonne accessibilité qui est indépendante de leur épaisseur. These 3 experiments show that the palladium nanoparticles remain available and the high percolating power of the membranes obtained with the manufacturing process according to the invention makes it possible to maintain good accessibility which is independent of their thickness.
En outre, l'analyse de ces données a permis de calculer la valeur de fréquence de rotation qui est de l'ordre de 0,1 mmol de substrat/(mmol Pd. minute). In addition, the analysis of these data made it possible to calculate the value of the rotation frequency which is of the order of 0.1 mmol of substrate / (mmol Pd. Minute).
Enfin, l'évaluation de la performance d'hydrogénation sur une trentaine de cycles avec ces 3 membranes catalytiques a montré une réduction très limitée de la vitesse d'hydrogénation : à savoir une diminution inférieure à 15%. Un simple rinçage avec de l'eau déminéralisée permet une régénération de la membrane obtenue avec le procédé de fabrication selon l'invention. Finally, the evaluation of the hydrogenation performance over about thirty cycles with these 3 catalytic membranes showed a very limited reduction in the hydrogenation rate: namely a decrease of less than 15%. Simple rinsing with demineralized water allows regeneration of the membrane obtained with the manufacturing process according to the invention.
Hydrogénation du 3-nitrophénol sur la membrane (sans recirculation) - Impact de la régénération du support Hydrogenation of 3-nitrophenol on the membrane (without recirculation) - Impact of support regeneration
Les effets du débit d'alimentation de 3-NP et de la régénération de la membrane obtenue selon le procédé de fabrication selon l'invention ont été étudiés. The effects of the feed rate of 3-NP and of the regeneration of the membrane obtained according to the manufacturing process according to the invention were studied.
Pour ce faire, des volumes croissants (jusqu'à 120 mL) d'une solution de 3- NP à une concentration de 200 mg 3-NP/L à un pH de 2,7 avec un débit de circulation de 20 ou 30 mL/minute ont circulé (un seul passage) au travers un échantillon de la membrane (27,2 mg). To do this, increasing volumes (up to 120 mL) of a solution of 3- NP at a concentration of 200 mg 3-NP / L at a pH of 2.7 with a circulation rate of 20 or 30 mL / minute circulated (single pass) through a membrane sample (27.2 mg).
En outre, la membrane catalytique a été alimentée en cette solution de 3- NP à ces mêmes débits de circulation de 20 ou 30 mL/minute mais en la régénérant (par simple rinçage avec de l'eau déminéralisée en utilisant un volume correspondant environ à 9 fois le volume occupé par ladite membrane) lorsque le volume de 3-NP qui avait circulé au travers la membrane catalytique avait atteint les valeurs de 40 mL et 80 mL. In addition, the catalytic membrane was supplied with this solution of 3- NP at these same circulation rates of 20 or 30 mL / minute but by regenerating it (by simple rinsing with demineralized water using a volume corresponding to approximately 9 times the volume occupied by said membrane) when the volume of 3-NP which had circulated through the catalytic membrane had reached the values of 40 mL and 80 mL.
La figure 5 représente un graphique des courbes de percée obtenues avec ces expérimentations. Il s'agit de l'évolution de la concentration résiduelle de 3-NP en fonction du volume de la solution de 3-NP passé au travers de la membrane catalytique lorsque : FIG. 5 represents a graph of the breakthrough curves obtained with these experiments. This is the change in the residual concentration of 3-NP as a function of the volume of the 3-NP solution passed through the catalytic membrane when:
- le débit d'alimentation était de 20 mL/minute (courbe « A ») ; - the feed rate was 20 mL / minute (curve “A”);
- le débit d'alimentation était de 30 mL/minute (courbe « B ») ; - the feed rate was 30 mL / minute (curve “B”);
- le débit d'alimentation était de 20 mL/minute et que la membrane a subi une régénération après le passage de 40 mL et de 80 mL de la solution de 3-NP (courbe « C ») ; - the feed rate was 20 mL / minute and that the membrane underwent regeneration after the passage of 40 mL and 80 mL of the 3-NP solution (curve “C”);
- le débit d'alimentation était de 30 mL/minute et que la membrane a subi une régénération après le passage de 40 mL et de 80 mL de la solution de 3-NP (courbe « D »). - The feed rate was 30 mL / minute and the membrane underwent regeneration after the passage of 40 mL and 80 mL of the 3-NP solution (curve “D”).
Les courbes de percée montrent une augmentation progressive de la concentration résiduelle de 3-NP en fonction du volume de la solution de 3-NP qui est passée au travers la membrane catalytique. L'augmentation du débit de circulation augmente la pente de la courbe de percée (en raison d'un temps de séjour insuffisant dans la membrane catalytique). The breakthrough curves show a progressive increase in the residual concentration of 3-NP as a function of the volume of the 3-NP solution which has passed through the catalytic membrane. Increasing the flow rate increases the slope of the breakthrough curve (due to insufficient residence time in the catalytic membrane).
L'interruption de l'alimentation de la membrane catalytique et sa régénération au moyen d'eau déminéralisée induit une rupture dans les courbes de percée et une reprise partielle de son efficacité catalytique. The interruption of the feed to the catalytic membrane and its regeneration by means of demineralized water induces a break in the breakthrough curves and a partial recovery of its catalytic efficiency.
Cette réaction catalytique d'hydrogénation du 3-NP illustre clairement la possibilité d'utiliser les membranes à haut pouvoir de percolation obtenues avec le procédé de fabrication selon l'invention pour l'immobilisation de métaux catalytiques et la synthèse de supports catalytiques à utiliser en régime dynamique à haut débit de filtration, avec confinement des nanoparticules. En outre, comme expliqué ci-dessus, ces membranes présentent l'avantage de pouvoir récupérer facilement les catalyseurs en fin de cycle de vie, par exemple par dégradation thermique des membranes. Les métaux précieux qui constituent les catalyseurs sont ainsi recyclés. This catalytic reaction for hydrogenation of 3-NP clearly illustrates the possibility of using the membranes with high percolation power obtained with the manufacturing process according to the invention for the immobilization of catalytic metals and the synthesis of catalytic supports to be used in dynamic regime at high filtration rate, with confinement of nanoparticles. In addition, as explained above, these membranes have the advantage of being able to easily recover the catalysts at the end of their life cycle, for example by thermal degradation of the membranes. The precious metals which constitute the catalysts are thus recycled.

Claims

REVENDICATIONS
1. Procédé de fabrication d'une membrane (1), caractérisé en ce qu'il comprend au moins les étapes suivantes : 1. A method of manufacturing a membrane (1), characterized in that it comprises at least the following steps:
a) on prépare un mélange qui contient au moins : a) a mixture is prepared which contains at least:
une solution aqueuse de polymère cationique dont le pH est compris entre 5 et 8, ledit polymère cationique présentant dans cette solution aqueuse des groupements chargés positivement; an aqueous solution of cationic polymer whose pH is between 5 and 8, said cationic polymer having positively charged groups in this aqueous solution;
une solution aqueuse de polymère anionique, ledit polymère anionique présentant dans cette solution aqueuse des groupements chargés négativement ; an aqueous solution of anionic polymer, said anionic polymer exhibiting in this aqueous solution negatively charged groups;
b) on agite le mélange ; b) the mixture is stirred;
c) on laisse maturer le mélange pour entraîner l'interaction ionique entre des groupements chargés positivement du polymère cationique et des groupements chargés négativement du polymère anionique, jusqu'à l'obtention au sein du mélange d'une membrane sous la forme d'un hydrogel ; c) the mixture is left to mature to cause the ionic interaction between positively charged groups of the cationic polymer and negatively charged groups of the anionic polymer, until a membrane is obtained within the mixture in the form of a hydrogel;
d) on ajoute au moins un agent de réticulation de manière à réticuler la membrane ; d) at least one crosslinking agent is added so as to crosslink the membrane;
e) on sèche la membrane réticulée obtenue à l'issue de l'étape d). e) the crosslinked membrane obtained at the end of step d) is dried.
2. Procédé de fabrication d'une membrane (1) selon la revendication 1, caractérisé en ce que le polymère cationique est choisi parmi la polyéthylèneimine, le poly(hydrochlorure d'allylamine), les chitosanes et les protéines. 2. A method of manufacturing a membrane (1) according to claim 1, characterized in that the cationic polymer is chosen from polyethyleneimine, poly (allylamine hydrochloride), chitosans and proteins.
3. Procédé de fabrication d'une membrane (1) selon la revendication 1 ou 2, caractérisé en ce que le polymère anionique est choisi parmi le poly(acide acrylique), la pectine, la carragénane, l'alginate et le poly(styrènesulfonate). 3. A method of manufacturing a membrane (1) according to claim 1 or 2, characterized in that the anionic polymer is chosen from poly (acrylic acid), pectin, carrageenan, alginate and poly (styrenesulfonate ).
4. Procédé de fabrication d'une membrane (1) selon l'une quelconque des revendications 1 à 3, caractérisé en ce que le mélange de l'étape a) comprend, en pourcentages massiques exprimés par rapport à la masse dudit mélange : 4. A method of manufacturing a membrane (1) according to any one of claims 1 to 3, characterized in that the mixture of step a) comprises, in percentages by weight expressed relative to the mass of said mixture:
entre 0,2% et 0,5%, de préférence entre 0,28% et 0,4%, du polymère cationique ; entre 0,6% et 1,5%, de préférence entre 0,8% et 1,2%, du polymère anionique. between 0.2% and 0.5%, preferably between 0.28% and 0.4%, of the cationic polymer; between 0.6% and 1.5%, preferably between 0.8% and 1.2%, of the anionic polymer.
5. Procédé de fabrication d'une membrane (1) selon l'une quelconque des revendications 1 à 4, caractérisé en ce qu'à l'étape a), on ajoute au mélange au moins un composé solide choisi parmi le charbon actif, la silice et l'argile. 5. A method of manufacturing a membrane (1) according to any one of claims 1 to 4, characterized in that in step a), at least one solid compound selected from activated carbon is added to the mixture, silica and clay.
6. Procédé de fabrication d'une membrane (1) selon l'une quelconque des revendications 1 à 5, caractérisé en ce que l'agent de réticulation est le glutaraldéhyde. 6. A method of manufacturing a membrane (1) according to any one of claims 1 to 5, characterized in that the crosslinking agent is glutaraldehyde.
7. Utilisation de la membrane (1) obtenue selon le procédé de fabrication selon l'une quelconque des revendications 1 à 6 pour le traitement d'effluents liquides ou gazeux. 7. Use of the membrane (1) obtained according to the manufacturing process according to any one of claims 1 to 6 for the treatment of liquid or gaseous effluents.
8. Utilisation de la membrane (1) obtenue selon le procédé de fabrication selon l'une quelconque des revendications 1 à 6 en tant que support pour la catalyse hétérogène. 8. Use of the membrane (1) obtained according to the manufacturing process according to any one of claims 1 to 6 as a support for heterogeneous catalysis.
9. Utilisation de la membrane (1) obtenue selon le procédé de fabrication selon l'une quelconque des revendications 1 à 6 en tant que support anti-microbiens. 9. Use of the membrane (1) obtained according to the manufacturing process according to any one of claims 1 to 6 as an anti-microbial support.
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