Patent Application
20200277205
The invention relates to a fluidic fluid-purifying device and an associated purifying process, for example used for cleaning wastewater, organic solutions and/or gases.
Wastewater is typically cleaned by treatment plants and then discharged, after treatment, into natural environments such as rivers or maritime coastal areas. The quality of wastewater treated by treatment plants is generally not sufficient to enable treated water to be reintroduced directly for human or animal use, thus preventing the preservation of freshwater reserves.
In a known manner, wastewater treatment can include:
However, these treatments are not able to purify wastewater of micropollutants. A “micropollutant” is typically defined as a pollutant present in wastewater at a low concentration, typically between 0.1 ng/L and 100 μg/L. Micropollutants can include persistent organic pollutants (POPs), used as pesticides, solvents, pharmaceuticals and industrial chemicals, and environmentally persistent pharmaceutical pollutants (EPPPs). Both types of micropollutant agents are toxic and dangerous to human and animal health, as well as to the balance of the ecosystem. Since 2001, the Stockholm Convention (Stockholm Convention on Persistent Organic Pollutants, 2001) aims to restrict the production and use of POPs.
In a known manner, activated carbon fitters can be used to purify wastewater of micropollutants, particularly organic compounds. Water treated by activated carbon fitters can be reused for industrial applications.
However, activated carbon fitters do not purify the water of sodium, many microbes, fluoride ions, and nitrates. Moreover, only specific types of activated carbons can filter out heavy metals such as lead.
In a known manner, ozonation can inactivate certain viruses, bacteria and/or cysts in wastewater. Ozonation is significantly more effective than chlorine treatment (for example, it is 3000 times more germicidal). Indeed, the rapid conversion of ozone to oxygen in the water makes it possible to limit or eliminate most of the toxic residues during treatment.
However, ozone is biologically extremely reactive and toxic to living organisms, which poses a danger when ozone treated water is subsequently used by humans or animals. In addition, the solubility of ozone varies significantly with temperature: continuous and seasonal adjustments of the concentration of ozone used in wastewater treatment are necessary to ensure optimal treatment without exceeding a toxic dose for users, and thus meet the quality standards imposed by the use of this treatment. In addition, ozonation leads to the formation of bromate in the water, which can be carcinogenic. Ozonation also requires installations using pure liquid oxygen, or compressed, purified and dried air, and electrical power, resulting in high water treatment costs.
It is also known to use filters comprising hollow fiber membranes to purify wastewater of micropollutants. Hollow fibers are generally between 0.6 mm and 2 mm in diameter and can be produced by extrusion of the membrane material. The water is treated by controlling a transmembrane flow.
However, hollow fiber membranes have a high hydraulic resistance. To control a purified water flow rate high enough for an industrial application, it is necessary to control pressures generally between 3 and 15 bar between the inlet and outlet of a membrane. In addition, the morphology of the fibers causes the pores to be blocked by objects to be filtered that are larger than the micropollutants. It is then necessary to backwash the fibers, i.e. to control a flow in the opposite direction of the wastewater treatment flow to clean the hollow fiber membranes. The pressures used for membrane cleaning are typically two to three times higher than the pressures used for water treatment: these pressures, combined with the use of chemical cleaning solutions, affect the mechanical performance of the fibers until they break.
U.S. Pat. No. 5,895,573 describes, to solve this problem, a device comprising successive membranes in which the diameter of the pores formed by the fibers decreases progressively with the direction of flow of the water to be treated.
However, this solution cannot treat wastewater at a pressure lower than 0.5 bar, while at the same time having a long service life due to the mechanical capacities of the fibers described. These pressure conditions make it impossible to directly connect a remediation device to a wastewater outlet and require an adaptation of the pressure at the terminals of the device.
More generally, the use of hollow fiber membranes limits the dimensioning of the water treatment device, limits the choice of materials that can be used to manufacture the treatment device, imposes constraints on the flow of wastewater in the treatment device, requires connections compatible with the use of hollow fiber membranes, in addition, the assembly and packaging of hollow fiber bundles for the manufacture of a purification device can be delicate and costly. Finally, the treatment of hollow fibers with depolluting or purification agents is inefficient, costly and energy-intensive.
In addition, US 20170081219 describes a water remediation system using electroflotation or electrocoagulation in a container with electrodes immersed in a wastewater stream. This method of remediation only treats pollutants that can be degraded by electroflotation or electrocoagulation.
U.S. Pat. No. 7,740,752 describes a remediation device comprising stacked treatment beds configured to receive liquid slicks to be remediated. This method slows the fluid to be treated and thus optimizes the sedimentation of the particles to be filtered in the fluid. This method does not filter pollutants that are too small to be subject to sedimentation.
Finally, Wang et al (Wang, N., Zhang, X., Wang, Y., Yu, W., & Chan, H. L., 2014, Microfluidic reactors for photocatalytic water purification, Lab on a Chip, 14(6), 1074-1082) describe a microfluidic channel whose inner surface has a layer of bismuth vanadate. Electron-hole pairs are produced by bismuth vanadate during tight excitation on it and allow the formation of free radicals in solution. These free radicals cause degradation of methylene blue in solution.
However, the purification flow rate of the microfluidic system described is at most 2 mL/h and is incompatible with industrial applications, for example at flow rates above 1000 L/h. One envisaged application of such a system is a kit for evaluating the performance of a photocatalytic material such as bismuth vanadate.
A purpose of the invention is to provide a fluid purifying device for purifying the fluid of micropollutants. Another purpose of the invention is to provide a purifying device for purifying a fluid at a flow rate high enough for an industrial application while applying a usual pressure difference, i.e. less than 5 bar, and preferentially 1 bar, between the inlet and the outlet of the device. Finally, another purpose of the invention is to provide a robust device, which can be reused after regeneration of the specific purification elements and/or high thermal or mechanical stress of the purification elements.
In particular, an object of the invention is a fluidic purification device adapted to purify a fluid of at least one pollutant, comprising a fluidic purification network, characterized in that the fluidic purification network is a three-dimensional array of microfluidic channels, each microfluidic channel being defined by one or more fluid-tight walls, each microfluidic channel having at least one zone on the inner surface of said microfluidic channel having at least one self-contained purification agent and each microfluidic channel having at such a zone a height of less than 60 μm in a direction normal to the main direction of fluid flow, the self-contained purification agent or agents and the dimensioning of said zones being configured to allow capture and/or degradation of at least 10% of the pollutants by said zones, for at least one flow of the fluid to be purified, the device comprising a plurality of distribution channels and a plurality of collection channels, the fluidic purification network connecting the distribution channels and the collection channels and being implemented at least by an array of microfluidic channels connected in parallel.
It is understood that with such a device, it is possible to remove one or more pollutants, particularly micropollutants, from a fluid by confining the fluid to be purified in microchannels. The diffusion of the micropollutants towards the purification agents presented to the walls makes it possible to purify the fluid without increasing the hydraulic resistance of the device and thus to allow the removal of micropollutants at industrial flow rates.
The invention is advantageously complemented by the following features, taken individually or in any of their technically possible combinations:
Another object of the invention is a purification assembly adapted to purify a fluid of at least one pollutant, comprising a plurality of fluidic devices, each fluidic device comprising a fluidic purification network, said fluidic purification network being a three-dimensional array of microfluidic channels, each microfluidic channel being defined by one or more fluid-tight walls, each microfluidic channel having at least one zone on the inner surface of said microfluidic channel having at least one self-contained purification agent and each microfluidic channel having at such a zone a height of less than 60 μm in a direction normal to the main direction of fluid flow, the self-contained purification agent or agents and the dimensioning of said zones being configured to allow a capture and/or degradation of at least 10% of the pollutants by said zones, for at least one flow of the fluid to be purified, the device comprising a plurality of distribution channels (40) and a plurality of collection channels (41), the fluidic purification network (8) connecting the distribution channels and the collection channels and being implemented at least by an array of microfluidic channels (9) connected in parallel, the fluidic devices being fluidly connected in series and/or in parallel.
Another object of the invention is a purification system comprising at least one fluidic purification device adapted to purify a fluid of at least one pollutant, each fluidic device comprising a fluidic purification network, said fluidic purification network being a three-dimensional array of microfluidic channels, each microfluidic channel being defined by one or more fluid-tight walls, each microfluidic channel having at least one zone on the inner surface of said microfluidic channel having at least one self-contained purification agent and each microfluidic channel having at such a zone a height of less than 60 μm in a direction normal to the main direction of fluid flow, the self-contained purification agent or agents and the dimensioning of said zones being configured to allow a capture and/or degradation of at least 10% of the pollutants by said zones, for at least one flow of the fluid to be purified, the device comprising a plurality of distribution channels (40) and a plurality of collection channels (41), the fluidic purification network (8) connecting the distribution channels and the collection channels and being implemented at least by an array of microfluidic channels (9) connected in parallel, the system also comprising a device for conditioning the temperature of a microfluidic channel.
The invention is advantageously complemented by the following features, taken individually or in any of their technically possible combinations:
Another object of the invention is a purification process adapted to purify a fluid of at least one pollutant, comprising a step in which the fluid is passed through a three-dimensional fluidic purification array of microfluidic channels at a flow rate of the fluid to be purified, each microfluidic channel comprising at least one zone on the inner surface of said microfluidic channel having at least one self-contained purification agent and each microfluidic channel having at such a zone a height of less than 60 μm in a direction normal to the main direction of fluid flow, the self-contained purification agent(s) and the dimensioning of said zones being configured to allow capture and/or degradation of at least 10% of the pollutants by said zones upon flow of the fluid at said flow rate through the array of microfluidic channels, the process comprising controlling a pressure difference between the inlet and outlet of a device so as to cause said fluid flow in said device, the device comprising at least one distribution channel connected to the inlet and at least one collection channel connected to the outlet, the fluidic purification network connecting the distribution channel or channels and the collection channel or channels, the hydrodynamic resistance of the distribution channel or channels and the collection channel or channels being strictly less than the hydrodynamic resistance of the fluidic purification network and the absolute value of the pressure difference being less than 5 bar.
The invention is advantageously complemented by the following features, taken individually or in any of their technically possible combinations:
Another object of the invention is a process for manufacturing a fluidic purification device adapted to purify a fluid of at least one pollutant, comprising a fluidic purification network, the fluidic purification network being a three-dimensional array of microfluidic channels, each microfluidic channel being defined by one or more fluid-tight walk, each microfluidic channel having at least one zone on the inner surface of said microfluidic channel having at least one self-contained purification agent and each microfluidic channel having at such a zone a height of less than 60 μm in a direction normal to the main direction of fluid flow, the self-contained purification agent(s) and the dimensioning of said zones being configured to allow capture and/or degradation of at least 10% of the pollutants by said zones, for at least one flow of the fluid to be purified, the fluidic device 1 comprising at least three stacked layers, at least two sides of one or more layers having, facing at least two layers, a depression pattern configured to form at least one two-dimensional array of microfluidic channels when the two layers are stacked, the material of each of the layers having a glass transition temperature below 0° C., the bonding between two layers being achieved solely by bringing the two layers into contact at a temperature between 0° C. and 50° C.
The term “pollutant” means any chemical and/or biological agent in a fluid that is at Least potentially toxic to humans and/or animals during use and/or consumption of that fluid, and particularly:
The term “purify”, in particular the term “purify a fluid of at least one pollutant” means the treatment to reduce the concentration of the pollutant in the fluid by at least 10%, preferentially by at least 40%, preferentially by at least 90% and preferentially by 100%.
A “purification agent” is any chemical and/or biological compound suitable for capturing and/or degrading a pollutant.
A “self-contained purification agent” is any purification agent that is capable of capturing and/or degrading a pollutant without physical stimulation external to the self-contained purification agent, such as light or electrical stimulation.
A “capturing agent” is any chemical compound, in particular any polymer, capable of trapping a substance or mixture of substances within its structure, immobilizing it and/or delaying its release to the outside.
“Channel length” is the size of a channel in the main direction of fluid flow.
“Channel width” is the maximum size of a channel in a direction transverse to the main direction of fluid flow.
“Channel height” is the minimum size of a channel in a direction transverse to the main direction of fluid flow.
A “tight” material is a material whose permeability to a fluid is less than 3000 bar at 25° C., i.e. 3000·10−10 cmSTP3·cm/cm2·s·cmHg at 25° C. where cm3STP corresponds to the standard cubic centimeter, cm corresponds to the thickness of the material and cmHg corresponds to the pressure drop across the material.
The “abatement rate” is the proportion of pollutant purified by a remediation system in relation to the quantity initially introduced into the system.
A “two-dimensional array” of elements is a two-dimensional array in the strict sense, i.e. all the elements can be distributed in a plane, but not in a tine. More specifically, a “two-dimensional channel array” is an array of channels, preferably interconnected, in which each channel is distributed in the same plane, regardless of the orientation of each channel. Preferentially. the microfluidic channels of the purification network of the invention form at least one two-dimensional array of channels.
A “three-dimensional array” of elements is a three-dimensional array in the strict sense, i.e. all the elements can be distributed in space, but not in a plane. More specifically, a “three-dimensional channel array” is an array of channels, preferably interconnected, in which each channel is distributed in space but not in a plane, regardless of the orientation of each channel.
“Hydrodynamic resistance” means the ratio between the upstream/downstream pressure difference in a channel or more generally a channel system or pipe, and the volume flow rate of the fluid passing through the channel or more generally the channel system or pipe. This resistance can be measured by the flow of a liquid in the channel, even in the case of a purification of a gaseous fluid by the fluidic device. The hydrodynamic resistance can be calculated for water at 25° C.
Other features and advantages will also emerge in the following description, which is purely illustrative and non-limiting, and should be read in conjunction with the appended figures, among which:
The Stokes-Einstein relationship, described by formula (1), relates the diffusion coefficient D of a pollutant 3 in a fluid to its mobility μ, to the absolute temperature T and to the Boltzmann constant kB.
D=μkBT (1)
Unlike large-diameter pollutants, which can for example be removed from water by sedimentation, many micropollutants have a high diffusion coefficient. Lead, for example, has a diffusion coefficient of about 5·10−10 m2·s−1 in water at 20° C.
Thus, in a confined environment, for example with a characteristic size of less than 100 μm and in a short time, for example less than 5 seconds, the pollutant 3 can meet the limits of the confined environment by diffusion with a high probability, for example more than 95%.
The Péclet number Pe (or Péclet mass number) is used to characterize the ratio between the transport of a pollutant 3 by convection and by diffusion, for example in a microfluidic channel. It can be defined by the formula (2):
where Lc is the characteristic length, and v is the advection velocity of the pollutant 3. The characteristic length is considered during the implementation of the invention to be equal to the length l′, i.e. the length of a zone 13 having self-contained purification agents within a microfluidic channel 4 in the main direction of fluid flow.
With reference to
With reference to
The microfluidic channel 9 has a zone 13 on the inner surface of said microfluidic channel, with self-contained purification agents 11. For example, this zone 13 may correspond to a wall 11 with a self-contained purification agent 11 within the microfluidic channel 9, illustrated in
10−10
Thus, as shown in the central part of
For example, for pollutants 3 such as carbamazepine, diuron, chlordecone and some heavy metals, the time required to interact with a self-contained purification agent 11 is less than one second in a microfluidic channel 9 with a height of 10 μm. In comparison, this time is of the order of 100 minutes and several hundred hours in channels with a height of 1 mm and 1 cm respectively. The quadratic reduction of this time with the height of the microfluidic channel 9 makes a purification of the fluid 2 possible by diffusion.
Thus, the flow of the fluid 2 in the confined microfluidic channels 9 with a height of less than 100 μm, preferentially 80 μm and preferentially 60 μm, purifies the fluid 2 by taking advantage of the effects of the diffusion of the pollutants 3, which, in known methods, has a purifying effect only in a negligible volume of the fluid 2.
The fluidic purification network 8 is a three-dimensional array of microfluidic channels 9, each microfluidic channel 9 having at least one self-contained purification agent 11 inside the microfluidic channel 9. Thus, it is possible to run the purification implemented by a single microfluidic channel 9 in parallel in order to achieve a flow rate compatible with industrial applications, for example greater than 10 L/h and preferentially 1000 L/h, contrary to the prejudices of the prior art (Wang et al., IV, Discussion, “[it] may not be used directly for practical water purification application”). In all the embodiments of the invention, the purification agent(s) 11 being self-contained, no light stimulation (or more generally no external stimulation) is required to capture and/or degrade a pollutant 3. Thus, it is possible to make the microfluidic channels 9 parallel in each dimension of space, regardless, for example, of the light absorption of the material forming the microfluidic channels 9.
With reference to
With reference to
The length of the distribution channel(s) 40 and/or the collection channel(s) 41 may be between 0.4 cm and 40 cm, preferentially between 2 cm and 10 cm and preferentially between 4 cm and 6 cm. The width of the distribution channels) 40 and/or the collection channel(s) 41 may be between 10 μm and 1 mm, preferentially between 50 μm and 200 μm and preferentially between 100 μm and 150 μm. Finally, the height of the distribution channel(s) 40 and/or the collection channel(s) 41 may be between 50 μm and 500 μm, preferentially between 100 μm and 300 μm and preferentially between 150 μm and 200 μm. The length of the microfluidic channels 9 of the fluidic purification network 8 can be between 50 μm and 100 mm, preferentially between 500 μm and 10 mm and preferentially between 1 mm and 3 mm. The width of the microfluidic channels 9 can be between 10 μm and 1 mm, preferentially between 50 μm and 200 μm and preferentially between 100 μm and 150 μm. The height of the microfluidic channels 9 of the fluidic purification network 8 can be between 1 μm and 500 μm, preferentially between 5 μm and 100 μm and preferentially between 10 μm and 60 μm. A microfluidic channel 9 can have several heights: a wall of the microfluidic channel 9 can, for example, have chevron-shaped reliefs.
With reference to
A first layer 17 can for example be made of thermoplastic elastomeric material (for example polystyrene-b-poly(ethylene-butylene)-b-polystyrene or SEBS, of polystyrene-b-polybutadiene-b-polystyrene or SBS, of syndiotactic polystyrene or SPS, of Kraton, registered trademark, or of Flexdym).
A second layer 18 may for example comprise a mixture of multiphase polymers of ethylene and vinyl alcohol (EVOH) and polycondensate of cyclodextrin(s) (PCCD), a thin layer of polypropylene, SEBS, SBS, SPS, Kraton (registered trademark) or Flexdym (registered trademark). A second layer 18 can also be partially functionalized by fungal laccases.
In general, a layer 17,18 can also be made of PDMS, PFPE, PMMA or any other known material suitable for microfabrication of microfluidic channels 9.
The fluidic device 1 may comprise one comprising at least one primary channel passing through a plurality of adjacent layers to open respectively into at least one distribution channel 40 and/or at least one collection channel 41 formed between two layers 17, 18. Aligned apertures through the different adjacent layers may form a primary channel 19. It is possible to compare a primary channel 19 with a via structure in microelectronics by analogy between the electric current and the flow of the fluid 2. A primary channel 19 can be included in the fluidic distribution network 6, and allow fluid 2 to be routed to the part of the fluidic distribution network 6 at the interface of a first layer 17 and a second layer 18. A primary channel 19 can also be included in the fluidic collection network 7 and allow the purified fluid 2 to be discharged from the part of the fluidic collection network 7 at the interface of a first layer 17 and a second layer 18. In general, a primary channel 19 can fluidly connect all parts of the fluidic distribution network 6 and/or all parts of the fluidic connection network 7.
The area of a section of a primary channel 19, normal to the main direction of flow, may be between 0.01 mm2 and 100 mm2, preferentially between 0.1 mm2 and 10 mm2 and preferentially between 0.8 mm2 and 5 mm2.
With reference to
Panel A in
Preferentially, the second layer 18 is made using a polycondensate of cyclodextrin(s), or a composition comprising at least one polycondensate of cyclodextrin(s) obtained by the reaction of the following compounds (A) to (C):
(A) at Least one cyclodextrin,
(B) at Least one Linear, branched and/or cyclic, saturated, unsaturated or aromatic polycarboxylic acid, and (C) at least one thermoplastic polymer polyol. The thermoplastic polymer polyol (C) is a copolymer of ethylene and vinyl alcohol (EVOH) and the polycondensate of cyclodextrin(s) thus obtained, or a composition comprising at least this polycondensate of cyclodextrin(s), is the self-contained purification agent 11 present on the surface of the second layer 18 and on the surface of a wall 10.
The term “polycondensate” refers to any polymer obtained by stepwise polymerization, where each step is a condensation reaction, which is carried out with removal of water, Monomers with two or more functional groups react to form first dimers, then longer trimers and oligomers, and then tong-chain polymers. The polycondensate of cyclodextrin(s) has a porous network which combines super-absorbent sponge-like properties with the ability to form inclusion complexes in the cavities of the cyclodextrin(s) immobilized within the polymer network, thereby allowing the capture of substances having an affinity with said polymer network. The polycondensate of cyclodextrin(s) allows the capture of, for example, metals or metallic elements, noted M, in their oxidation state 0 (M(0)), as well as substances such as medicines and pesticides. The polycondensate of cyclodextrin(s) is also obtainable by the reaction of the following compounds (A) to (C): (A) at least one cyclodextrin, (B) a linear or branched saturated aliphatic polycarboxylic acid, and (C) a copolymer of ethylene and vinyl alcohol (EVOH). The cyclodextrin (A) used is a compound of general structure (3) below, or one of the derivatives of this compound such as methyl, hydroxyalkyl, sulfoalkyl, sulfate or sugar-substituted cyclodextrins:
The cyclodextrin (A) can be selected from α-cyclodextrin, β-cyclodextrin and γ-cyclodextrin. The polycondensate of cyclodextrin is obtained by the reaction of compounds (A) to (C) using only a cyclodextrin (A). The polycondensate of cyclodextrins can also be obtained by the reaction of compounds (A) to (C) using a mixture of cyclodextrins (A), for example a mixture of two, three or more cyclodextrins (A). When this mixture of cyclodextrins (A) comprises two cyclodextrins, one of these two cyclodextrins is advantageously the β-cyclodextrin. Such a mixture of cyclodextrins (A) may in particular comprise, relative to the total mass of the said mixture, the following proportions by mass:
In this particular mixture of two cyclodextrins (A), the mass proportion of β-cyclodextrin can advantageously be between 20% to 50% and preferentially between 25% to 40% of the total mass of the cyclodextrin mixture. In this particular mixture of two cyclodextrins (A), the proportion by mass of β-cyclodextrin or γ-cyclodextrin may be between 50% and 80% and preferentially between 60% and 75% of the total mass of said mixture of cyclodextrins.
The compound (B) used may be a linear, branched or cyclic, saturated, unsaturated or aromatic polycarboxylic acid. Such polycarboxylic acid(s), which comprise at least two carboxyl groups —COOH, may be linear, branched and/or cyclic. They can also be saturated, unsaturated or aromatic. This or these polycarboxylic acid(s) may comprise from 2 to 50, advantageously from 3 to 36, preferentially from 4 to 18 and even more preferentially from 4 to 12 carbon atoms. Compound (B) may, for example, be a saturated linear or branched aliphatic polycarboxylic acid, and/or selected from malic acid, citric acid, aconitic acid, 1,2,3-propanetricarboxylic acid, 1,2,3,4-butanetetracarboxylic acid, oxydisuccinic acid and thiodisuccinic acid. The compound (C) is a copolymer of ethylene and vinyl alcohol, known by the abbreviation EVOH. The polycondensate of cyclodextrin(s) used may be in the form of a solid compound that can be advantageously processed, for example in the form of pebbles, granules, powder or nanotubes. Being a solid compound, the polycondensate of cyclodextrin(s) can also be molded. The polycondensate of cyclodextrin(s) is obtainable by the reaction of the following compounds (A) to (C): (A) at least one cyclodextrin, (B) at least one linear, branched and/or cyclic, saturated, unsaturated or aromatic polycarboxylic acid, and (C) at least one copolymer of ethylene and vinyl alcohol (EVOH). In addition, the composition may include one or more other compound(s), which may impart properties complementary to those of the polycondensate of cyclodextrin(s), such as magnetic properties. Such compounds may include activated carbon, paints, magnetic compounds and antibacterial agents (for example silver or copper microparticles). Thus, this polycondensate of cyclodextrin(s) alone, or in admixture with one or more other compounds in a composition, enables a substance or a mixture of substances to be trapped within its structure, to immobilize it and/or to delay its release to the outside.
The polycondensate of cyclodextrin(s) and/or the composition comprising one or more polycondensate of cyclodextrin(s) can be used as a capture agent for at least one substance selected from a metallic element and an organic molecule.
Where the substance is a metallic element, this metallic element M may in particular be selected from aluminum, silver, iron, boron, tin, copper, zinc, lead, nickel, cadmium, chromium, mercury and gold.
When the substance is an organic molecule, this organic molecule has an octanol/water partition coefficient, denoted LogKow greater than or equal to 1.5. The polycondensate of cyclodextrin(s) and the composition can be used as a capture agent for at least one organic molecule having a LogKow, of between 1.5 and 10 and preferentially between 5 and 8.
The pollutant 3 may be an organic molecule chosen from a herbicide such as diuron, a drug, for example an anticonvulsant drug such as carbamazepine, an endocrine disruptor such as polychlorinated biphenyls (PCBs or pyralenes), phthalates and polycyclic aromatic hydrocarbons (PAHs) such as benzopyrene, these organic molecules being known to be particularly difficult to clean up environments containing them.
In particular, the polycondensate of cyclodextrin(s) according to the invention is particularly effective as a capture agent for the congeners of polychlorinated phenyls known by the abbreviations PCB 28, PCB 52, PCB 101, PCB 118, PCB 138, PCB 153 and PCB 180.
Alternatively, the polycondensate is obtainable by the reaction in which the compound (A) is selected from hydroxypropyl-β-cyclodextrin (HPCD), methyl-β-cyclodextrin (MCD) and carboxymethyl-β-cyclodextrin (CMCD).
Panel B in
Panel C in
The parallelization of the microfluidic channels 9 increases the total flow of the fluidic device 1. With reference to
With reference to
With reference to
The surface occupied, in the projection onto the principal plane of the interface between two superimposed layers, by the distribution channel or channels 40 and by the collection channel or channels 41 on the side of a layer is advantageously between 20% and 45% of the total surface of said side, preferentially between 6% and 25% of the total surface of said side and preferentially between 13% and 17% of the total surface of said side.
The surface area occupied, in the projection onto the principal plane f the interface between two superimposed layers, by the microfluidic channel or channels 9 on the side of a layer is advantageously between 20% and 70% of the total surface area of said side and preferentially between 40% and 50% of the total surface area of said side.
Thus, the layout of the fluidic distribution network 6, the fluidic collections network 7 and the fluidic purification network 8 is optimized to meet two criteria: on the one hand, to minimize the ratio between the hydrodynamic resistance of the fluidic distribution network 6 and the fluidic collection network 7 in relation to the hydrodynamic resistance of the fluidic purification network 8, and on the other hand, to maximize the surface density occupied by the fluidic purification network 8 on a layer.
With reference to
The thickness of the first layers 17 can be between 0.05 mm and 1 cm, preferentially between 0.5 mm and 2 mm and preferentially between 1 mm and 1.5 mm.
The primary channels 19 make it possible, in the case of a stack 14 of several first layers 17 and several second layers 18 to distribute or collect the fluid 2 in the channels present at each interface between a first layer 17 and a second layer 18. The dashed tines show channels at the interface of the two layers 17, 18 allowing the primary channels 19 to be connected to the other channels at the interface.
With reference to
In general, at Least three layers are stacked, at least two sides of one or more layers having, facing at least two layers, a depression pattern configured to form at least two two-dimensional arrays of microfluidic channels when the at least three layers are stacked. Thus, it is possible to parallelize the two-dimensional arrays of microfluidic channels 9 formed between two layers so as to form a three-dimensional array of micro-fluidic channels 9. Thus, the high degree of parallelization of the microfluidic channels 9 makes it possible to reduce the hydrodynamic resistance of the fluidic purification network 8 and thus to circulate fluid 2 by controlling or monitoring the system and/or the purification network 8 with a pressure variation between inlet and outlet of less than 5 bar, and preferentially less than 1 bar.
With reference to
With reference to
With reference to
The distribution connector 22 and collection connector 23 can be made of polydimethylsiloxane (PDMS) and produced by soft lithography. They can also be made of thermoplastic elastomers and structured by hot printing lithography, injection molding, 3D printing, or stereolithography. Materials such as polystyrene, polycarbonate, polyimide or other thermoplastic elastomeric materials such as polyurethane or blockamide materials can also be used. The distribution connector 22 and collection connector 23 can also be made of silicon, glass or metallic material (for example Ni, NiCo alloy, aluminum, stainless steel): thus, the fluidic device 1 can mechanically and chemically resist an organic fluid flow 2. The distribution connector 22 and collection connector 23 can be manufactured, using these materials, by 3D printing, micromachining, electroplating, wet etching and/or reactive ion etching.
Washing fluids and/or regeneration fluids for the self-contained purification agents can be introduced into the fluidic device 1. Washing fluid means a fluid for removing impurities trapped in a fluidic device 1. Regeneration fluid means a fluid that allows the release of the pollutants 3 captured by the self-contained purification agents 11, or allows the self-contained purification agents 11 to degrade the pollutants 3 with an efficiency substantially equal to the sensitivity to the initial time at which the fluid 2 is introduced into the fluidic device 1. A combination of cleaning and regeneration fluids can be introduced into the fluidic device 1, for example at a flow rate between 0.01 μL/min and 250 L/min, preferentially between 1 μL/min and 2 L/min, and preferentially between 0.7 mL/min and 3 mL/min. A flow of washing and/or regeneration fluid can be coupled with thermal conditioning. For example, the temperature of the fluid 2 can be conditioned before it is introduced into a fluidic device 1. The circulation of washing and/or regeneration fluid may be discontinuous, open or closed Loop. A 5% citric acid solution can be used as a washing and regeneration solution. An oxidizing O2 plasma can also be used. This plasma can circulate, in a closed Loop, at a flow rate between 0.1 μL/min and 0.5 μL/min.
The washing and/or regeneration fluids may be recirculated in the same direction or in, the opposite direction to the flow of the fluid 2. In addition, the circulation and/or recirculation of the washing and/or regeneration fluid may be pulsed, i.e. the flow rate is periodic and variable, for example in slots.
A temperature conditioning device 27 is adapted to condition the temperature inside the frame 28. Another temperature conditioning device 27 can be adapted to condition the temperature of the fluidic device 1. The temperatures of the frame and/or fluidic device 1 can be adjusted by the temperature conditioning devices between 20° C. and 250° C. For example, temperature conditioning devices may include temperature sensors to maintain a setpoint temperature by closed-loop temperature control. Thus, it is possible to adjust the purification efficiency of the fluid 2 passing through the fluidic device 1: according to the Stokes-Einstein equation, the diffusion constant of a pollutant 3 changes Linearly with temperature. An increase in temperature thus makes it possible to increase the speed at which a pollutant 3 is likely to encounter a wall with a self-contained purification agent 11.
A pump 30 is used to control the flow 16 of the fluid 2 in the purification system. Pump 30 is suitable to drive a fluid flow rate in the purification system between 0.01 μL/min and 2500 L/min.
A pressure controller 31 can control a pressure inside the frame 28 whose absolute value is less than 5 bar and preferentially less than 1 bar. A pressure controller can also be adapted to control a fluid flow rate by pressure difference in the fluidic device 1. The pressure difference between inlet and outlet can be negative to attract the fluid 2 to the outlet or positive to push the fluid 2 to the outlet.
A first fluidic detection unit 32 can be fluidly connected downstream of the fluidic device 1. The fluidic detection unit 32 can measure the pollutant concentration 3 of the fluid 2 at the outlet of the fluidic device 1.
A second fluidic detection unit 33 can be fluidly connected downstream of the fluidic device 1. The second fluidic detection unit 33 allows specific analysis of washing and/or regeneration liquids.
A first outlet manifold 34 and a second outlet manifold 35 are fluidly connected to the fluidic device 1. The first outlet manifold 34 is used to collect the fluid 2 purified or partially purified by the fluidic device 1. The second manifold 35 allows to collect the regenerating fluid or the washing fluid downstream of the fluidic device 1. Fluids can be selectively conveyed to one or other of the manifolds for example by means of a valve controlled by a control unit 26.
A collection unit for regenerating fluids and/or washing fluids 37 is connected to the second outlet manifold 35.
A control unit 26 is electrically connected to the pump 30, pressure controller 31, selector valve 38, temperature conditioning devices 27, first and second outlet manifolds 34 and 35. The control unit can be a computer comprising a microprocessor and a memory. Data communication between the central unit and the other components of a purification system can be implemented via one or more wireless links. The different manifolds and/or valves can be adapted to redirect the different fluids upstream of the fluidic device 1 to allow recirculation of the fluid 2.
The detection units 32,33 may include sensors, microsystems or lab-on-a-chip to perform various fluid analyses downstream of the fluidic device 1, and transmit these analyses to the control unit. This data allows closed-loop control of recirculation in the purification system. Control units can also include fluid turbidity sensors and/or UV spectrometers. More generally, the system is adapted to purify the fluid 2 by implementing at least one recirculation of the fluid 2 in the microfluidic channel array.
The various arrows illustrate possible fluid flows in the system, the continuous lines illustrate fluid connections in the system, the dashed lines illustrate connections allowing heat transfer and the gray lines illustrate a network allowing pressure control at the ends of the network.
With reference to
With reference to
In Step 181, a fluid 2 is passed through a microfluidic channel array 9 at a flow rate of the fluid to be purified. The speed of the fluid flow 2 or its rate of flow may be controlled by a pump 30 or a pressure controller 31, and selected to allow the self-contained purification agents 11 capture and/or degradation of at least 10%, preferentially at least 40% and preferentially at least 90% and preferentially 100% of the pollutants 3, at the flow rate of the flow. The proportion of the pollutants 3 can be measured by the first detection unit 32 downstream of the device 1. The formula (2) is used to calculate the Péclet number Pe corresponding to a pollutant 3 in the flow. The diffusion coefficient D and the length l′ are known values. The value of the flow rate can be calculated according to the geometry of the different channels of the system and according to the pressure applied to the system. Thus, in step 181 a fluid flow 2 is controlled in which Pe is less than 104, preferentially less than 10 and preferentially less than 1. The flow velocity of the fluid 2 can also be chosen so that the Péclet number of the pollutant 3 in fluid 2 is between 10−2 and 104, preferentially between 10−1 and 10 and preferentially between 1 and 102 and: thus the diffusion can allow the pollutants 3 of a fluid 2 to be partially or totally captured or degraded by one or more self-contained purification agents 11, while corresponding to a flow rate sufficient for industrial applications of the purification process. In order to purify a fluid 2 with the same pollutant 3 abatement rate, it is possible to circulate the fluid in the fluidic device 1 only once at a low Péclet number of the pollutant 3, for example less than 10 and preferentially less than 1, or to carry out recirculation of the fluid 2 at a higher flow rate and therefore at a higher Péclet number of the pollutant 3, for example less than 10000 and preferentially less than 1000, and more preferentially less than 1000.
In step 182, the microfluidic channels are washed or regenerated as described above. This step may be followed by step 181. Thus, it is possible to purify a large volume of the fluid 2 by interrupting the flow of the fluid 2 by washing or regeneration of the self-contained purification agents 11.
In step 183, the fluid 2 is recirculated. Step 183 can be performed in parallel with step 181. Recirculation can be implemented by recirculating the fluid 2 in the same direction as the first circulation of the fluid 2, or in the opposite direction. In addition, the circulation and/or recirculation of the fluid 2 may be pulsed, i.e. the flow rate is not constant and is periodic. Pulsed recirculation can optimize the interaction between a pollutant 3 and a self-contained purification agent 11.
The manufacture of the microfluidic channels 9, and more generally, of the channels of the fluidic distribution network 6, the fluidic connection network 7 and the fluidic purification network 8, can be implemented using microfabrication techniques using for example a substrate made of silicon, glass, but also thin, thick, rigid or flexible polymer material. A substrate can be molded, etched or micromachined. A mechanically robust substrate can present 2D and 3D microfluidic elements. The channels of the different fluidic networks can also be made by a low-cost lithographic microfabrication process using hot printing. For example, it is possible to thermomould a CD made of thermoplastic elastomeric material (similar to a plastic audio/video CD) so as to produce a plurality of interconnected microchannels, a plurality of interconnected fluid reservoirs and other dosing and mixing units.
The purification of previously polluted water by a purification system comprising a fluidic purification device 1 was implemented.
Flows 16 of water previously polluted by various pollutants 3 were controlled in a fluidic device 1 comprising a stack 14 of 23 sub-stacks comprising a first layer 17 and a second layer 18. A controlled pressure difference of 175 Pa between the inlet and outlet of the purification system results in a fluid flow rate 2 of 2.3 L/min. The first layers 17 of thermoplastic elastomer (Flexdym, registered trademark) have a thickness of 1.3 mm and recessed structures produced by printing lithography on one side 21, using a mold microstructured with epoxy type resin. The second purification layers 18 are 0.5 mm thick. The material of the second layers 18 is an EVOH/PCCD mixture, the mass concentration of PCCD being approximately 38%. The second layers 18 are manufactured beforehand by an extrusion process, The height of the microfluidic channels 9 is 10 μm.
Table 2 shows the development of the abatement rate of pollutant 3 with the flow rate of fluid 2 controlled in the purification system. Water polluted with lead at a mass concentration of 0.1 μg/L is initially introduced into the purification system. Purification is carried out at room temperature (20° C.), at a continuously controlled flow rate, without washing the system and without the release of the pollutants 3 by the self-contained purification agents 11.
Table 3 shows the development of the abatement rate of pollutant 3 with the flow rate of fluid 2 controlled in the purification system. Water polluted with carbamazepine at a mass concentration of 0.1 μg/L0 is initially introduced into the purification system. Purification is carried out at room temperature (20° C.), at a continuously controlled flow rate, without washing the system and without the release of the pollutants 3 by the self-contained purification agents 11.
| Number | Date | Country | Kind |
|---|---|---|---|
| 1758527 | Sep 2017 | FR | national |
| Filing Document | Filing Date | Country | Kind |
|---|---|---|---|
| PCT/EP2018/074955 | 9/14/2018 | WO | 00 |
