Fixed-bed electrochemical flow reactor based on at least one volume electrode, preferably based on biosourced carbon, and its use in various applications and in particular for decontaminating a liquid medium

Abstract

The present invention relates to a fixed-bed electrochemical flow reactor comprising at least one first volume electrode, preferably based on biosourced carbon, and a separator configured to separate the first volume electrode from a second surface or volume electrode and to ensure compression at least on said first volume electrode, to its use in various applications such as the decontamination of a liquid medium comprising at least one organic pollutant, the disinfection of water by electrochlorination, the electrolysis of water, the desalination of seawater, the storage of energy (e.g. as a redox flow battery or supercapacitor), or the production of electrical energy from osmotic energy, and to a method for decontaminating a liquid medium comprising at least one organic pollutant used in said reactor. Figure to be published: figure 1

Description

Title of the invention: fixed-bed electrochemical flow reactor based on at least one volume electrode, preferably based on biosourced carbon, and its use in various applications and in particular for decontaminating a liquid medium

[0001] The present invention relates to a fixed-bed electrochemical flow reactor comprising at least one first volume electrode, preferably based on biosourced carbon, and a separator configured to separate the first volume electrode from a second surface or volume electrode and to ensure compression at least on said first volume electrode, to its use in various applications such as the decontamination of a liquid medium comprising at least one organic pollutant, the disinfection of water by electrochlorination, the electrolysis of water, the desalination of seawater, the storage of energy (e.g. as a redox flow battery or supercapacitor), or the production of electrical energy from osmotic energy, and to a method for decontaminating a liquid medium comprising at least one organic pollutant used in said reactor.

[0002] Electrochemical processes differ from conventional chemical processes by the heterogeneous nature of the electrochemical reaction and by the presence of an electric field. Furthermore, they often use corrosive media (concentrated solutions, temperatures above room temperature, molten salts, organic media) and the materials of the parts constituting the cell must be chemically inert and retain their mechanical and thermal properties. Furthermore, the electrode materials are chosen to promote the desired electrochemical reaction and to minimize the importance of side reactions such as degradation of the solvent or the products formed. The cells used in industry must meet these material criteria while minimizing the ohmic drop and ensuring a high value of the transfer conductance.Currently, most commercially available cells are of the filter press type (or capillary gap cell) comprising at least one electrode, at least one counter-electrode, and possibly at least one membrane interposed between the electrode and the counter-electrode. The electrode and the counter-electrode are flat and parallel. The electrolyte solution circulates in the cell through a thin channel. The filter press type cell is characterized by inter-electrode distances that can be very small (e.g. 0.2 mm), thus aiming to minimize ohmic drops. However, this type of cell can cause flow disturbances, with agitated zones, dead volumes, and in some cases short circuits.

[0003] The global contamination of surface water, groundwater and drinking water by organic micropollutants such as cosmetics, pesticides, pharmaceuticals and steroid hormones poses potential risks to human health and the ecosystem. Since organic micropollutants are resistant to biological degradation, most wastewater treatment plants cannot effectively remove them from treated effluents and cannot prevent them from entering the environment. Wastewater treatment processes for removing organic pollutants have been proposed. In particular, it is known to use filter press type electrochemical reactors to depollute effluents comprising organic pollutants by oxidation.Pollution control is carried out by a process called the "electro-Fenton process", in which the hydroxyl radical (OH•), a powerful oxidant of organic pollutants, is produced from an aqueous solution comprising ferrous ions and hydrogen peroxide. The ferrous ions are themselves generated electrochemically within the electrochemical reactor. There are two types of filter press reactors: intermittent flow with a single chamber, or continuous parallel flow in which the pollutants flow parallel to the surface of the anode and the cathode. However, the efficiency of pollutant removal is not satisfactory.

[0004] Furthermore, other filter press type reactors have been proposed for performing effluent decontamination by electro-Fenton. For example, Ren et al., Chemical Engineering Journal, 2016, 298, 55-67 described a vertical flow reactor implementing the electro-Fenton process comprising a plurality of PbO2 anodes and a plurality of modified graphite felt cathodes alternating over about ten compartments. The pollutants flow perpendicular to the surface of the anodes and cathodes.

[0005] Such reactors, although they have a continuous flow effluent feed, generally have low pressure resistance. The electrodes designed in the form of plates are inserted into openings created in the reactor structure which are sealed with silicone to prevent leaks. However, silicone does not have a high pressure resistance. In addition, the design of the reactor does not facilitate regular replacement of the electrodes, an important step to maintain optimal performance under industrial conditions. Finally, lead is toxic and although graphite represents one of the most commonly used electrode materials, its production generates carbon emissions and / or requires a significant energy input.

[0006] There is therefore a need for new electrochemical reactor architectures, in particular for the decontamination of effluents but also for other applications in the field of electrochemistry, which make it possible to improve electrochemical performance, while ensuring a reduction in the carbon footprint.

[0007] The first subject of the invention is a fixed-bed electrochemical flow reactor, characterized in that it comprises: - at least one first volume electrode comprising an electrically conductive material, preferably a bio-sourced carbon, - at least one second surface or volume electrode comprising an electrically conductive material, the second electrode being electrically connected to said first electrode, - at least one first inlet and at least one first outlet, configured respectively to bring a liquid electrolyte in a continuous flow into the reactor, and to bring said liquid electrolyte out in a continuous flow from the reactor, and - at least one separator comprising at least one dielectric part in contact with said first and second electrodes, said separator being configured to separate the first and second electrodes, to provide compression on said first electrode, and to allow movement of the liquid electrolyte in continuous flow from the first inlet to the first outlet.

[0008] Thanks to the architecture of the reactor of the invention, and in particular thanks to the presence of at least one volume electrode and the presence of a separator which is configured to separate the first and second electrodes, to ensure compression on said first electrode, and to allow a movement of the liquid electrolyte in continuous flow from the first inlet to the first outlet, a better contact surface is thus obtained between the liquid electrolyte and the electrodes, and increased turbulence, which makes it possible to promote electrochemical transfers and mass transport with good homogenization of the reaction medium within the reactor. Furthermore, the reactor of the invention is robust, modular in that it can be used to implement various electrochemical processes, and adapted to the requirements of industry.The reactor allows in particular to adapt the mass volumes of the electrodes to optimize the efficiency of the specific electrochemical process implemented in said reactor. This reactor configuration is also suitable for parallel and series assembly to meet the needs of electrochemical processes in terms of flow and residence time.

[0009] The reactor of the invention is a fixed-bed flow electrochemical reactor. In other words, the liquid electrolyte moves within the electrochemical reactor in a continuous flow. The reactor is said to be fixed-bed. In other words, when the liquid electrolyte moves within the electrochemical reactor, and in particular passes through the first and second electrodes, said first and second electrodes remain fixed (i.e. are immobilized) and the liquid electrolyte passes through the empty spaces or holes. Therefore, the first and second electrodes remain in a static state while the liquid electrolyte moves. This thus helps to avoid side reactions within the reactor.

[0010] The first electrode

[0011] The first volume electrode comprises an electrically conductive material, preferably a bio-sourced carbon.

[0012] The electrically conductive material may have an electrical resistivity of at most approximately 15,000 Qm, and particularly preferably ranging from approximately 1x108 Qm to approximately 1 Qm.

[0013] In a particularly preferred manner, the first volume electrode is essentially made of a biosourced carbon.

[0014] In the invention, the term “essentially consisting” means that the biosourced carbon represents at least approximately 90% by mass, preferably at least approximately 95% by mass, and particularly preferably approximately 100% by mass, relative to the total mass of the first volume electrode.

[0015] In the invention, a bio-sourced carbon is a carbon derived from biomass or raw materials of plant and / or animal origin (and not of fossil or petrochemical origin). It is in particular obtained by extraction of biomass or raw materials of plant and / or animal origin, or obtained by reactions applied to biomass or raw materials of plant and / or animal origin.

[0016] The use of bio-based carbon as a bulk electrode allows for reducing the costs of electrode materials, improving the efficiency of electrochemical reactions, also reducing the associated energy costs. Finally, bio-based carbon is a material that can be produced from renewable resources, providing a sustainable alternative to petroleum-based electrode materials that can present supply problems.

[0017] The biosourced carbon is preferably biochar.

[0018] Biochar is a contraction of "bio-charcoal", meaning a charcoal of plant origin. It is generally obtained by thermal treatment (pyrolysis or gasification) of one or more sources of biomass such as by-products of the wood industry, crop residues, solid waste, green waste, food waste, etc.

[0019] According to a particular embodiment of the invention, the biochar is obtained by heat treatment of one or more sources of biomass at a temperature of at least approximately 400°C, and preferably at a temperature ranging from approximately 700°C to 1500°C.

[0020] The source of biomass is preferably cedar, pine, fir, cypress, hemlock, larch, spruce, birch, elm, eucalyptus, hickory, ebony, ironwood, maple, oak, poplar, or bamboo. Cedar wood is preferred, particularly because it is rich in lignin and has a low ash content.

[0021] The conductive properties and / or the specific chemical properties of the biochar can be modulated based on the heat treatment conditions and / or the nature of the biomass.

[0022] The bio-sourced carbon preferably has a specific surface area ranging from about 10 m2 / g to about 3500 m2 / g, particularly preferably from about 50 m2 / g to about 1500 m2 / g, and more particularly preferably from about 50 m2 / g to about 500 m2 / g. Such a specific surface area is beneficial for electrochemical applications, as it allows for better interaction between the liquid electrolyte and the first electrode, leading to improved performance. Pre-treatment or post-treatment may increase the specific surface area.

[0023] In the invention, the specific surface area can be determined by the Brunauer-Emmet-Teller method (BET method), in particular using adsorption isotherms carried out with CO2.

[0024] Biosourced carbon, and in particular biochar, can be functionalized by chemical groups or elements such as oxygenated groups such as carboxyls, lactones, phenols, phosphate or polyphosphate groups, nitrogen groups such as amines, pyridines, pyrroles, pyridones, sulfate groups such as sulfoxides, sulfones, sulfonic acids, thiophenes, thioethers, metal composites or metal oxides, the metal being chosen from iron, manganese, magnesium, zinc, copper, cobalt, and one of their mixtures, in particular by activation or doping. This can improve its conductive properties and / or give it specific chemical properties.

[0025] The biosourced carbon preferably has an electrical resistivity of at most approximately 15,000 Qm, and particularly preferably ranging from approximately 1x108 Qm to approximately 1 Qm.

[0026] In the invention, the resistivity is determined by the four-point probe technique.

[0027] The biosourced carbon is preferably in the form of granules, chips or pellets, particularly preferably of average size ranging from 250 μm to 100 mm, and more particularly preferably of average size ranging from 1 mm to 50 mm.

[0028] This form of granules, chips or pellets is advantageous for an industrial application, and in particular makes it possible to obtain a first flexible electrode in terms of replacement and maintenance, and having a better surface area. contact. This also makes it possible to obtain a reactor with increased adaptability to implement different electrochemical processes.

[0029] In the invention, the average size of the granules, chips, or pellets is determined by particle size analysis or by imaging techniques.

[0030] The first electrode may have a volume V1 (in cm3), preferably from 1 cm3 to 1*106 cm3, and more particularly preferably from 5 cm3 to 5000 cm3.

[0031] According to a preferred embodiment of the invention, the first electrode has a mass volume ranging from 0.1 to 10 cm3 / g, preferably from 2.5 to 5.0 cm3 / g, and particularly preferably from 3.0 to 4.5 cm3 / g. Such a mass volume guarantees a good electrical connection within the biosourced carbon particles.

[0032] In the present invention, a volume electrode is an electrode whose active surface is distributed in a volume. Conversely, a surface electrode is defined by two orthogonal main dimensions, and is generally in the form of plates with a small thickness. An electrode is considered to be a plate when the ratio of the thickness with each of the two orthogonal main dimensions (thickness / length and thickness / width) of said electrode is less than 0.3, preferably less than 0.1.

[0033] The second electrode

[0034] The second electrode is a surface or volume electrode comprising an electrically conductive material, and preferably being essentially made of an electrically conductive material.

[0035] In the invention, the term "essentially consisting" means that the electrically conductive material represents at least approximately 90% by mass, preferably at least approximately 95% by mass, and particularly preferably approximately 100% by mass, relative to the total mass of the second surface or volume electrode.

[0036] The electrically conductive material may have an electrical resistivity of at most approximately 15,000 Qm, and particularly preferably ranging from approximately 1x108 Qm to approximately 1 Qm.

[0037] The electrically conductive material may be chosen from ferrous waste, iron, iron alloys such as steel, bio-sourced carbon, and one of their mixtures, preferably bio-sourced carbon or low-carbon steel (i.e. with at most 0.3% by mass of carbon, relative to the total mass of the steel).

[0038] The biosourced carbon is preferably biochar.

[0039] According to a particular embodiment of the invention, the biochar of the second electrode is obtained by heat treatment of one or more sources of biomass at a temperature of at least approximately 400°C, and preferably at a temperature ranging from approximately 700°C to 1500°C.

[0040] The biomass source is preferably cedar, pine, fir, cypress, hemlock, larch, spruce, birch, elm, eucalyptus, hickory, ebony, ironwood, maple, oak, poplar or bamboo.

[0041] The conductive properties and / or the specific chemical properties of the biochar can be modulated based on the heat treatment conditions and / or the nature of the biomass.

[0042] The bio-sourced carbon of the second electrode preferably has a specific surface area ranging from approximately 10 m2 / g to 3500 m2 / g, particularly preferably ranging from approximately 50 m2 / g to 1500 m2 / g, and more particularly preferably ranging from approximately 50 m2 / g to 500 m2 / g. Such a specific surface area is beneficial for electrochemical applications, as it allows for better interaction between the liquid electrolyte and the second electrode, leading to improved performance.

[0043] Biosourced carbon, and in particular biochar, can be functionalized by chemical groups or elements such as oxygenated groups such as carboxyls, lactones, phenols, phosphate or polyphosphate groups, nitrogen groups such as amines, pyridines, pyrroles, pyridones, sulfate groups such as sulfoxides, sulfones, sulfonic acids, thiophenes, thioethers, metal or metal oxide composites, the metal being chosen from iron, manganese, magnesium, zinc, copper, cobalt, and one of their mixtures, in particular by activation or doping. This can improve its conductive properties and / or give it specific chemical properties.

[0044] When the second electrode is a volume electrode, the second electrode preferably has a mass volume of electrically conductive material ranging from 0.1 to 10 cmVg, and particularly preferably from 0.5 to 5 cmVg.

[0045] When the second electrode is a volume electrode, the biosourced carbon is preferably in the form of granules, chips, or pellets, particularly preferably of average size ranging from 250 μm to 100 mm, and more particularly preferably of average size ranging from 1 mm to 50 mm.

[0046] This form of granules, chips or pellets is advantageous for an industrial application, and in particular makes it possible to obtain a second electrode that is flexible in terms of replacement and maintenance, and has a better contact surface. This also makes it possible to obtain a reactor with increased adaptability for implementing different electrochemical processes.

[0047] When the second electrode is a volume electrode, the iron or iron alloy is preferably in the form of a fibrous or woven material, such as wool (iron wool or steel wool).

[0048] When the second electrode is a surface electrode, the second electrode is preferably in the form of a plate, cylinder, prism, sphere or a combination of these geometries.

[0049] The second electrode is preferably a volume electrode.

[0050] The second electrode can then have a volume V2 (in cm3).

[0051] According to a preferred embodiment, the first and second electrodes are such that the volume ratio V1 / V2 ranges from about 1 to 100, and particularly preferably the volume ratio V1 / V2 ranges from about 1 to 50. When the volume ratio V1 / V2 is greater than 100, the corrosion current may be too high. When the volume ratio V1 / V2 is less than 1, the corrosion current may be too low.

[0052] Entrance and exit

[0053] The reactor comprises at least one first inlet and at least one first outlet, configured respectively to bring a liquid electrolyte in a continuous flow into the reactor, and to leave said liquid electrolyte in a continuous flow from the reactor.

[0054] Therefore, the liquid electrolyte circulates and moves within the reactor from the first inlet to the first outlet in a continuous flow.

[0055] The reactor may further comprise at least one means configured to obtain a movement of the liquid electrolyte in continuous flow within said reactor with a flow rate ranging from 0.1 to 5*108 ml / min, and preferably ranging from 1 to 2.5*107 ml / min.

[0056] On a smaller scale, other flow rate ranges can be used such as a flow rate ranging from 5 to 100 ml / min, and preferably ranging from 30 to 70 ml / min.

[0057] The means may be a pump such as a peristaltic pump, a syringe pump, a propeller pump, a positive displacement pump, a centrifugal pump, or a diaphragm pump.

[0058] The liquid electrolyte is preferably a medium poor in bacteria and / or nutrients.

[0059] The liquid electrolyte is preferably an aqueous electrolyte.

[0060] The separator comprises at least one dielectric portion in contact with said first and second electrodes.

[0061] In the invention, the expression "dielectric part" means an electrically insulating part, i.e. a part whose electrical conductivity can be at most 1.108 S / m (siemens per meter), preferably at most 1.109 S / m, and particularly preferably at most 1.10 10 S / m (siemens per meter), measured at 25°C in direct current.

[0062] The presence of this dielectric part makes it possible to avoid any current supply or leakage within the separator and coming from one or more electrodes. This dielectric part is in contact (i.e. in direct physical contact) with said first and second electrodes. In other words, the separator is in contact with said first and second electrodes by or via said dielectric portion.

[0063] The dielectric portion of the separator preferably comprises at least one polymer material, and particularly preferably consists essentially of a polymer material.

[0064] In the invention, the term "polymer" includes homo- and copolymers.

[0065] In the invention, the term “essentially consisting” means that the material polymer represents at least approximately 90% by mass, preferably at least approximately 95% by mass, and particularly preferably approximately 100% by mass, relative to the total mass of the dielectric part.

[0066] The polymer material may be chosen from polyamides, polycarbonates, polyetherimides, polyolefins (PP, PET, PBT), polystyrenes (PS, ABS), polyacrylates (PMA), polymethacrylates (PMMA), polyaryletherketones (PEEK), and a mixture thereof.

[0067] Polymethacrylates are preferred as the polymer material. This allows for better stability, better mechanical properties, and it is an easy-to-machine polymer material.

[0068] The metallic material may be chosen from the following metals and metal alloys: titanium, copper, aluminum, iron, and stainless steel.

[0069] When the separator is made of polymer material, it can be manufactured by 3D printing by stereolithography.

[0070] Said separator is configured to separate the first and second electrodes. In other words, it is positioned within the reactor so as to separate the first and second electrodes. This thus makes it possible to avoid any physical contact between the electrodes and thus any risk of short circuit.

[0071] More particularly, the separator is interposed between the first and second electrodes.

[0072] The separator is also configured to provide compression on said first electrode.

[0073] The first electrode being a volume electrode, the compression on it makes it possible to modulate its density or its mass volume, and thus to promote good electrical contact between the biosourced carbon particles within said first electrode; and also between the biosourced carbon particles and a current collector if it exists. The compression also ensures optimal contact between the first electrode and the current collector if it exists, thus reducing the contact resistance.

[0074] The separator is further preferably also configured to provide compression on said second electrode. The compression ensures in particular optimal contact between the second electrode and a current collector if one exists, reducing thus the contact resistance. Furthermore, when the second electrode is a volume electrode, the compression on it makes it possible to modulate its density or its mass volume, and thus to promote good electrical contact between the particles of electrically conductive material within said second electrode; and also between the particles of electrically conductive material and the current collector if it exists.

[0075] According to a preferred embodiment of the invention, a compressive force is applied by the separator to said first electrode and / or to the second electrode, and preferably to said first and second electrodes respectively.

[0076] The compression force can range from approximately 1 kPa to 10,000 kPa, and particularly preferably from approximately 10 kPa to 1,000 kPa.

[0077] The separator is further preferably configured to control the volume ratio of the first and second volume electrodes, at constant reactor volume.

[0078] The dimensions of the separator are adjustable in length, width, diameter, thickness, depth, etc. This makes it possible on the one hand to vary the distance between the electrodes (the separator separates the electrodes and a dielectric part of said separator is in contact with them), and on the other hand to vary the volume of each of the volume electrodes (the separator ensures compression on the volume electrodes).

[0079] According to a preferred embodiment of the invention, the separator comprises at least one empty or hollow volume or space between the first and second electrodes. This thus makes it possible to reduce the charge losses. Furthermore, the liquid electrolyte can move within this empty or hollow volume or space.

[0080] Advantageously, the separator may be in the form of a piston, a spring, or a hollow element, such as a hollow cylinder. The hollow element (respectively the piston) may then be in contact (by its dielectric part) with the first and second electrodes by two ends positioned on either side of the hollow element (respectively the piston).

[0081] The separator is also configured to allow movement of the liquid electrolyte in a continuous flow from the first inlet to the first outlet.

[0082] Thus, the separator is configured to allow the liquid electrolyte to flow in a continuous flow within the reactor, and in particular from the first inlet to the first outlet. In particular, it allows the liquid electrolyte to pass selectively in a continuous flow within the reactor.

[0083] According to a preferred embodiment, the separator is a hollow element provided with at least one closing element, such as a cover, having one or more or openings, such as a grid, to allow the continuous flow of liquid electrolyte from the first electrode or the second electrode to the first outlet.

[0084] The openings preferably have a size smaller than the average size of the particles of electrically conductive material of the second electrode and of the biosourced carbon particles of the first electrode. This makes it possible to prevent the passage of said particles, while allowing the passage of the liquid electrolyte within the separator.

[0085] The separator as a hollow element may comprise a first closure element and a second closure element, the first closure element being preferentially in contact with said first electrode and the second closure element being preferentially in contact with said second electrode. In this preferred embodiment, the first and second closure elements may be positioned on either side of the hollow element, at two ends of said separator, so that they are in contact with said first and second electrodes respectively.

[0086] The first and second closure elements preferably have the same definition as the closure element described above.

[0087] According to a preferred embodiment of the invention, the separator is a rigid separator.

[0088] Thanks to the rigidity of the separator, this prevents the separator from deforming during compression on the electrode(s).

[0089] Particularly preferably, the separator has a Young's modulus of at least 1.5 GPa, and more particularly preferably of at most 250 GPa.

[0090] In the invention, Young's modulus is determined by a test standardized by the American Society for Testing Materials (ASTM El 11) which takes into account the strength and stress of a material to which a uniaxial force is applied incrementally or continuously.

[0091] The separator may be made of polymer material as defined in the invention, including the dielectric part, or the separator may be made of metallic material as defined in the invention, with the exception of the dielectric part which is as defined in the invention.

[0092] The metallic material may have a Young's modulus ranging from approximately 100 to 200 GPa.

[0093] The polymer material may have a Young's modulus ranging from 2 to 5 GPa.

[0094] The separator, by its rigid and hollow design, allows a uniform distribution of pressure on said first and second electrodes, ensuring optimal electrical conductivity through the electrode materials. This central compression provided by the separator allows to achieve a density of the particles forming the volume electrodes appropriate for obtaining good electrochemical performance of the reactor. The length of the separator is adapted to the V1 / V2 electrode volume ratio for a constant reactor volume, thus allowing precise modulation of the electrochemical configuration without compromising the efficiency of the process. In addition, the design of the separator facilitates the application of sufficient compression on the volume electrodes, essential to maintain optimal electrical resistivity and ensure adequate conductivity within the reactor.

[0095] An extensible structure of the separator, with its ability to dynamically adjust the length of the separator in the context of an application resulting in a loss of material from the volume electrodes, would make it possible to ensure optimal compression and electrical conductivity of the electrodes.

[0096] The closing and opening elements integrated into the separator allow the application of a uniform radial force on all of the volume electrodes. This feature ensures a constant density of the electrode materials throughout the reactor, contributing to the uniformity of the electrochemical reaction. The amount of electrode material used is calculated to fill the space delimited by the separator, taking into account the compression necessary to achieve and maintain the desired electrical conductivity.

[0097] The reactor may further comprise at least one first current collector, preferably in contact with the first electrode.

[0098] In particular, the first electrode is interposed between the first collector and the separator.

[0099] The first collector may be made of copper, silver, steel, nickel, titanium, graphite or any other corrosion-resistant conductive material.

[0100] The reactor may further comprise at least one second current collector, preferably in contact with the second electrode.

[0101] In particular, the second electrode is interposed between the second collector and the separator.

[0102] The first current collector (respectively the second current collector) is configured to provide compression on the first volume electrode (respectively on the second surface or volume electrode).

[0103] The liquid electrolyte can move in a continuous flow within the reactor in one of the following ways: - the liquid electrolyte can move in a continuous flow from the first inlet to the first outlet in the direction DF, passing successively in this order possibly the second current collector if it exists, the second electrode, the separator, the first electrode, and possibly the first current collector if it exists exists, or - (a) a first liquid electrolyte can move in continuous flow from the first inlet to the first outlet in a direction DFi, then a direction DFF perpendicular to the direction DN, passing successively in this order possibly the second current collector if it exists, the second electrode and a first compartment of the separator, and - (b) a second liquid electrolyte can move in continuous flow from a second inlet to a second outlet in a direction DF2, then a direction DF2' perpendicular to the direction DF2, passing successively in this order possibly the first current collector if it exists, the first electrode and a second compartment of the separator.

[0104] The implementation of one or other of the above alternatives will depend on the electrochemical reaction to be implemented which will itself condition the structure of the separator to be used (presence of one or more membranes, of one or more flows, etc. requiring the presence of one or more compartments within the separator).

[0105] In the second alternative, the reactor further comprises a second inlet and a second outlet. The liquid electrolyte comprises a first liquid electrolyte and a second liquid electrolyte. The separator comprises a first compartment and a second compartment.

[0106] Other alternatives are possible (other inlets and / or outlets, other compartments, other flows, etc.) depending on the electrochemical reaction to be implemented.

[0107] The separator can be single-compartment or single-block, or multi-compartment or multi-block.

[0108] According to a first variant, the separator is single-compartment or single-block.

[0109] According to this first variant, the liquid electrolyte can enter the reactor through the first inlet in a direction DF, said first inlet being positioned upstream of (i.e. before) the second electrode (even more preferably upstream of the second current collector if it exists) and the liquid electrolyte can leave the reactor through the first outlet in the direction DF, said first outlet being positioned downstream of (i.e. after) the first electrode (even more preferably downstream of the first current collector if it exists). In this embodiment, the liquid electrolyte can then move in a continuous flow from the first inlet to the first outlet in the direction DF, passing successively in this order possibly the second current collector if it exists, the second electrode, the separator, the first electrode, and possibly the first current collector if it exists.

[0110] According to this first variant, the reactor can be: - a reactor for implementing a galvano-fenton process, and the electrically conductive material of the second electrode is chosen from iron, ferrous waste and iron alloys; or - a reactor for carrying out electrochlorination, and the electrically conductive material of the second electrode is a bio-sourced carbon; or - a supercapacitor, and the electrically conductive material of the second electrode is a bio-sourced carbon.

[0111] According to a second variant, the separator is multi-compartmental or multi-block.

[0112] According to this second variant, a first liquid electrolyte can enter the reactor via the first inlet in a direction DFi, said first inlet being positioned upstream of (i.e. before) the second electrode (even more preferably upstream of the second current collector if it exists) and the first liquid electrolyte can leave the reactor via the first outlet in a direction DFF perpendicular to the direction DF[, said first outlet being positioned downstream of (i.e. after) the second electrode, perpendicular to the first inlet and at the level of a first compartment of the separator.

[0113] In this embodiment, the first liquid electrolyte can then move in continuous flow from the first inlet to the first outlet in a direction DF[, then a direction DFF, passing successively in this order possibly the second current collector if it exists, the second electrode and the first compartment of the separator.

[0114] According to this embodiment of the second variant, the reactor may further comprise a second inlet and a second outlet so that a second liquid electrolyte may enter the reactor via the second inlet in a direction DF2, said second inlet being positioned upstream of (i.e. before) the first electrode (even more preferably upstream of the first current collector if it exists) and the second liquid electrolyte may exit the reactor via the second outlet in a direction DF2' perpendicular to the direction DF2, said second outlet being positioned downstream of (i.e. after) the first electrode, perpendicular to the second inlet and at the level of a second compartment of the separator.

[0115] In this embodiment, the second liquid electrolyte can then move in a continuous flow from the second inlet to the second outlet in a direction DF2, then a direction DF2, passing successively in this order possibly the first current collector if it exists, the first electrode and the second compartment of the separator.

[0116] The first and second compartments are preferably separated by an ion exchange membrane. This ensures ionic continuity within the reactor.

[0117] According to this embodiment of the second variant, the reactor can be: - a reactor for carrying out water electrolysis, and the electrically conductive material of the second electrode is a bio-sourced carbon; or - a redox flow battery, and the electrically conductive material of the second electrode is a bio-sourced carbon.

[0118] The separator may further comprise a third compartment interposed between the first and second compartments such that the first and third compartments are preferably separated by an ion exchange membrane such as a cation membrane, and the second and third compartments are preferably separated by an ion exchange membrane such as an anion membrane.

[0119] In this embodiment, the reaction preferably further comprises a third inlet and a third outlet, such that a third liquid electrolyte can enter the reactor through the third inlet in a direction DF3, said third inlet being positioned at the third compartment of the separator, and the third liquid electrolyte can exit the reactor through the third outlet in the direction DF3, said third outlet being positioned at the third compartment of the separator.

[0120] In this embodiment, the third liquid electrolyte can then move in a continuous flow from the third inlet to the third outlet in a direction DF3 crossing the third compartment of the separator.

[0121] According to this embodiment of the second variant, the reactor can be: - a reactor for implementing seawater desalination, and the electrically conductive material of the second electrode is a bio-sourced carbon; or - for the production of electrical energy from osmotic energy (the difference in salinity between fresh water (rivers) and salt water (sea water), and the electrically conductive material of the second electrode is a bio-sourced carbon.

[0122] The liquid electrolyte is preferably a medium poor in bacteria and / or nutrients.

[0123] The second object of the invention is the use of an electrochemical reactor in accordance with the first object of the invention, for depolluting a liquid medium comprising at least one organic pollutant, for disinfecting water by electrochlorination, for implementing water electrolysis, for implementing seawater desalination, for energy storage (e.g. as a redox flow battery or supercapacitor), or for the production of electrical energy from osmotic energy (the difference in salinity between fresh water (rivers) and salt water (seawater)).

[0124] The reactor according to the first object is modular in that it is possible to modify the first electrode (electrically conductive material) and the second electrode (electrically conductive material, surface or volume electrode, etc.), the shape and structure of the separator, as well as the number of inlets and outlets. Its configuration is therefore versatile and allows it to be used in a large number of applications.

[0125] Electrochlorination

[0126] The reactor can be used to disinfect water by electrochlorination. This involves producing chlorine and other chemical derivatives from saline solutions.

[0127] Electrochlorination is frequently used to disinfect water, whether for drinking water, swimming pools, or industrial cooling systems.

[0128] Chlorine produced by electrochlorination can also kill a variety of harmful microorganisms.

[0129] According to this embodiment, the electrically conductive material of the first electrode is preferably a biosourced carbon as defined in the invention, the electrically conductive material of the second electrode is preferably a biosourced carbon as defined in the invention, and the second electrode is preferably a volume electrode.

[0130] Electrolysis of water

[0131] The reactor can be used to carry out the electrolysis of water.

[0132] In the energy sector, this reactor configuration can facilitate the electrochemical production of decarbonized dihydrogen by the electrolysis of water.

[0133] According to this embodiment, the electrically conductive material of the first electrode is preferably a biosourced carbon as defined in the invention, the electrically conductive material of the second electrode is preferably a biosourced carbon as defined in the invention, and particularly preferably a biosourced carbon functionalized with at least one metal or metal oxide (acting as a catalyst), said metal being able to be chosen from iron, manganese, magnesium, calcium, zinc, copper, and cobalt. This can then make it possible to optimize the electrolysis process for maximum electrochemical performance.

[0134] The second electrode is preferably a volume electrode.

[0135] Energy storage

[0136] The reactor can be used for energy storage (eg as a redox flow battery or supercapacitor).

[0137] According to this embodiment, the electrically conductive material of the first electrode is preferably a biosourced carbon as defined in the invention, the electrically conductive material of the second electrode is preferably a biosourced carbon as defined in the invention, and the second electrode is preferably potentially a volume electrode.

[0138] The reactor can in particular be used as a redox flow battery. The use of large surface area bio-based carbon-based volume electrodes improves electrochemical performance by increasing the rate of redox reactions, resulting in higher energy density. The separator allows for control of electrical contact in the reactor and can improve overall efficiency.

[0139] The reactor can in particular be used as a supercapacitor.

[0140] This energy storage device is based on the accumulation of ions in a liquid electrolyte during the charging phase, creating a double electrical layer on the surface of the electrodes. This double electrical layer stores energy. The use of volume electrodes based on bio-sourced carbon with a large specific surface area improves electrochemical performance and effectively replaces the activated carbon traditionally used.

[0141] Desalination of sea water

[0142] The reactor can be used to implement seawater desalination, particularly as an electrodialysis cell. Salt ions in the seawater are attracted to the charged electrodes, moving them away from the water and making it potable at the separator.

[0143] Seawater desalination is a process for removing anions and cations from seawater. In particular, electrical energy is injected to force the migration of anions and cations towards the electrodes.

[0144] According to this embodiment, the electrically conductive material of the first electrode is preferably a biosourced carbon as defined in the invention, the electrically conductive material of the second electrode is preferably a biosourced carbon as defined in the invention, and the second electrode is preferably a volume electrode.

[0145] The use of volume electrodes based on biosourced carbon with a large specific surface area makes it possible to increase the efficiency of electrodialysis.

[0146] In addition, the reactor operating in continuous flow, can make the electrodialysis process more efficient and adaptable to different scales, from small portable installations to large industrial installations.

[0147] Energy production

[0148] The reactor can be used for the production of electrical energy from osmotic energy.

[0149] The production of electrical energy from osmotic energy is based on the spontaneous migration of ions between seawater and freshwater to create an ionic current which can be converted into electric current by means of electrodes and membranes.

[0150] This makes it possible to produce electrical energy thanks to the difference in salinity between fresh water (rivers) and salt water (sea water).

[0151] According to this embodiment, the electrically conductive material of the first electrode is preferably a biosourced carbon as defined in the invention, the electrically conductive material of the second electrode is preferably a biosourced carbon as defined in the invention, and the second electrode is preferably a volume electrode.

[0152] Use of the reactor in an electro-fenton process

[0153] The reactor of the invention can be used to implement an electro-Fenton process. In the state-of-the-art processes, the first electrode is a copper electrode and the second electrode is an iron electrode. However, the implementation of copper as an electrode material in the process has several disadvantages: copper ions can be released into the effluent to be treated, which can lead to secondary contamination and adverse effects on human health and the environment; the extraction, processing and manufacturing of copper generate significant economic costs and environmental impacts; and copper mining requires significant energy inputs, which increases production costs and contributes to greenhouse gas emissions.The reactor of the invention provides an abundant and bio-sourced alternative first electrode material, while guaranteeing good electrochemical performance.

[0154] The use of the reactor for decontaminating a liquid medium comprising at least one organic pollutant is preferred.

[0155] The third subject of the invention is a method for decontaminating a liquid medium comprising at least one organic pollutant, preferably chosen from industrial effluents, waste water, used oil emulsions, and oil-laden waste water emulsions, comprising at least one organic pollutant, characterized in that: - said method comprises at least one step of degrading said organic pollutant in an oxidizing medium generated by the use of an electrochemical reactor in accordance with the first subject of the invention, and in which: - the liquid electrolyte comprises said liquid medium and at least one oxidizing agent, and - the electrically conductive material of the first electrode is a bio-sourced carbon, and the electrically conductive material of the second electrode is chosen from iron, ferrous waste and iron alloys.

[0156] The reuse of wastewater is a political and socio-economic issue for the development of a sustainable city. This development requires the reduction of micropolluting substances (pesticides, endocrine disruptors, plasticizers, antibiotics, etc.) present in treated water leaving treatment plants. In In this context, micropollutant treatment processes, such as advanced oxidation processes (AOP), have been booming in recent years. These processes are not yet selected as a complementary treatment solution in wastewater treatment plants due to their high additional cost and significant energy consumption. Thanks to the use of the reactor of the invention in Galvano-Fenton (GF) technology, wastewater can be treated by degrading micropollutants while producing electrical energy. This process is based on the use of inexpensive electrodes based on iron and bio-sourced carbon in the presence of an oxidizing agent (eg H2O2) to catalyze the Fenton reaction and generate OH- radicals capable of degrading recalcitrant pollutants in wastewater.Biochar is a by-product of the thermal decomposition of residual biomass that is generally produced from locally available biological waste, such as agricultural and forestry residues, at very low costs. The designed reactor thus promotes the circular bioeconomy, by combining degradation of micropollutants, energy production and recovery of biomass waste in a sustainable manner and with a low ecological footprint.

[0157] The organic pollutant may be chosen from plasticizers (such as bisphenols), herbicides (such as atrazine), pesticides (such as Alachlor: 2-chloro-2',6'-diethyl-N-(methoxymethyl)acetanilide), endocrine disruptors (such as ethinylestradiol), pharmaceuticals (such as paracetamol, carbamazepine), perfluorocarbons (also known by the acronym "PFC"), fungicides (such as Chlorothalonil: 2-(aminocarbonyl)-3,5,6-trichloro-4-cyanobenzenesulfonic acid), and a mixture thereof.

[0158] The oxidizing agent may be hydrogen peroxide or sodium percarbonate. Sodium percarbonate has the advantage of being easy to transport and / or store and non-toxic.

[0159] According to a preferred embodiment, the liquid electrolyte has a pH ranging from approximately 1 to 14, and particularly preferably ranging from approximately 1 to 5.

[0160] According to a preferred embodiment, the liquid electrolyte comprises from 1x106 to 1000 ppm approximately of organic pollutant(s), and particularly preferably from 1x10 1 to 100 ppm approximately of organic pollutant(s).

[0161] According to a preferred embodiment, the liquid electrolyte comprises from 1x103 to 100 mM approximately of hydrogen peroxide, and particularly preferably from 1x10 1 to 10 mM approximately of hydrogen peroxide, as oxidizing agent.

[0162] According to a preferred embodiment, the liquid electrolyte has an electrical conductivity ranging from approximately 1x105 to 60 mS / cm, and particularly preferably from approximately 0.001 to 50 mS / cm.

[0163] Preferably, the degradation step is carried out at a temperature ranging from approximately 0 to 50°C.

[0164] According to a preferred embodiment, the first and second electrodes are such that the volume ratio V1 / V2 ranges from approximately 1 to 10, and particularly preferably the volume ratio V1 / V2 ranges from approximately 1 to 5. This makes it possible to guarantee better pollution control performance. Brief description of the drawings

[0165] The invention is illustrated by the figures and examples which follow, to which it is however not limited. [Fig.l] shows two schematic representations and a photograph of the electrochemical reactor according to the invention. [Fig.2] shows a schematic representation of the electrochemical reactor according to the invention in the pseudo-stationary state. [Fig. 3] shows a schematic representation of the electrochemical reactor according to the invention in the semi-continuous state. [Fig. 4] shows a schematic representation of the batch configuration of a prior art reactor, a schematic representation of the continuous flow configuration of a reactor according to the invention, and percentage discoloration versus time curves for both configurations. [Fig.5] shows the power curves for both batch configurations of a prior art reactor and continuous flow configurations of a reactor according to the invention. [Fig.6] shows the ratio of the concentration of the micropollutant solution at time t to the concentration of the micropollutant solution initially as a function of time when the micropollutant is atrazine (ATZ), alachlor (ALA), bisphenol A (BPA), and ethinylestradiol (EE2). [Fig.7] shows the configuration of a reactor according to the invention for electrochlorination and as a supercapacitor. [Fig.8] shows the configuration of a reactor according to the invention for the electrolysis of water and as a redox flow battery. [Fig.9] shows the configuration of a reactor according to the invention for the desalination of sea water, or for the production of electrical energy from osmotic energy. Examples

[0166] The raw materials used in the examples are listed below: - aqueous hydrogen peroxide solution (35% aqueous solution by weight), Sigma Aldrich, - dichloromethane (>99.5% purity), Sigma Aldrich, - sodium hydroxide (>98.0% purity in the form of pellets), Sigma Aldrich, - sulfuric acid (95.0-98.0% purity), Sigma Aldrich - potassium chloride (>99.0% purity), Sigma Aldrich, - potassium ferricyanide (III) (>98.5% purity, K3Fe(CN)6), Sigma Aldrich, - malachite green (VM) oxalate (>90.0% purity), Sigma Aldrich, - atrazine (ATZ) (>98.0% purity), Sigma Aldrich, - alachlor (ALA) (>98.0% purity), Sigma Aldrich, - ethinylestradiol (EE2), Sigma Aldrich, - bisphenol A (BPA) (>99.0% purity), Sigma Aldrich.

[0167] The iron plate (surface area of ​​6 cm2, 9 grams of iron) is marketed by GoodFellow.

[0168] Steel wool (carbon content >0.3% by mass) is marketed by RS Components.

[0169] Copper collectors are marketed by RS Components.

[0170] The photopolymerizable stereolithographic resin “Clear V4” is marketed by Makershop. It comprises a methacrylate oligomer, a methacrylate monomer, and <1% diphenyl (2,4,6 trimethylbenzoyl) phosphine oxide (TMDPO) as a photoinitiator. The cedar wood is marketed by a steel mill.

[0171] All solutions were prepared with deionized water (18 MΩ).

[0172] Unless otherwise stated, all materials were used as received from the fa bricants, without purification.

[0173] Specific surface area measurements

[0174] The specific surface area was measured using the Brunauer-Emmet-Teller (BET) model. To do this, a biochar sample was placed in a hermetic cell, where liquid nitrogen was used to cool the system to a cryogenic temperature allowing the adsorption of the selected gas (CO2) under vacuum, at different stages of constant pressure. The analysis was carried out using an automatic surface area and porosity analyzer sold under the trade name “Micro 100” by 3P instruments.

[0175] Measurement of electrical resistivity

[0176] To characterize the electrical resistivity of biochar, a biochar sample (dimensions approximately 40 mm x 10 mm x 0.5-1.5 mm) was polished with 2000 grit sandpaper to a smooth surface. The measurement was performed with a 4-point tungsten carbide probe, each point having a radius of 125 μm with a spacing of 1.27 mm between them. The system was mounted on a stand sold under the trade name "S-302" by Signatone connected to a source meter sold under the trade name "Keithley 2450". Based on this measurement configuration, the resistivity calculation must take into account the finished thickness of the sample. For this purpose, an equation that considers the resistivity of a two-dimensional sheet was corrected with a thickness factor (also considered isotropic) as shown in the following equation (1): [Math.l] , ■ Zt\ F JT ] / t\ p = ^-20-^(-) = 7^* P -M; (1) in which: nline represents the ideal resistance of an infinite two-dimensional sheet where R ™sh-2D simply corresponds to the resistance measured between two probes (R=V / I), -1 represents the thickness of the sample, and - Fl corresponds to a correction factor which takes into account the t / s ratio, s being the distance between the tips of the probes.

[0177] This correction factor is dimensionless and becomes negligible when the thickness is significantly less than the distance from the probe tips (if t«s then Fl—>1) and decreases with increasing t. The correction factor Fl can be expressed according to the following equation (2):

[0178] [Math.2]

[0179] Measurement of the mass volume of the biochar volume electrode

[0180] This measurement was made on biochar granules. They were carried out under ap Application of a compressive force on the granules in order to obtain a density guaranteeing adequate electrical conductivity between the granules themselves as well as between the granules and the current collector. The experimental device comprises a piston and an empty, graduated translucent cylinder allowing the compression of the biochar granules. Copper current collectors placed at the end of the piston and at the base of the cylinder facilitate electrical resistance measurements and allow analysis of the variation of the latter as a function of the density (the mass volume) of the granules, induced by compression. A quantity of 1 g of biochar granules was introduced into the cylinder. Without compression, the mass of biochar occupies an initial volume determined by the graduation of the cylinder, establishing an initial mass volume. Compression is then exerted on the biochar granules using the piston.An ohmmeter is used to measure the resistance between the two leads. current readers during compression. This compression induces a reduction in volume and a decrease in electrical resistance. Compression is stopped when the electrical resistance value stops decreasing. The volume of the biochar pellets for this compression state is recorded using the cylinder graduations to determine the corresponding mass volume. The results indicate that the electrical resistance has a minimum value of 4.86 ohms for a maximum mass volume of 3.87 cm3.g *.

[0181] Measurement of the mass volume of the steel wool volume electrode

[0182] This measurement was made as previously described for the volume electrode at biochar. The results indicate a maximum mass volume of 2.24 cm3.g *.

[0183] Monitoring the degradation of malachite green (VM)

[0184] The concentration of VM during the duration of the experiments was obtained by absorbance measurements of the medium at a wavelength of 618 nm using a spectrophotometer sold under the trade name "Hach-Lange DR 3900". By using a calibration curve for the absorbance values ​​obtained at Xmax= 618 nm for different solutions of known concentration of VM, the concentration of VM was determined at different times of the reaction, allowing the degradation of the compound to be followed. The percentage of decolorization was calculated using the following equation (3):

[0185] [Math.3] Co ~ Q %Discoloration = —;--* 100 (3) where Co represents the initial concentration of VM and Ct represents its concentration at a given time t (min).

[0186] Example 1: preparation of biochar

[0187] In this example 1, the cedar wood received was mechanically cut into pieces measuring 70 mm x 20 mm x 3 mm. They were washed with deionized water with stirring for 20 minutes, then subjected to a drying step at 70°C for approximately 24 hours. Then, a pyrolysis heat treatment was carried out in a furnace sold under the trade name “RSH 50 / 500 / 13” by Nabertherm. The furnace was first placed under vacuum (e.g. using a vane pump) then under a nitrogen atmosphere at a flow rate of 100 Lh 1 (maintained with a controller sold under the trade name “B 410” by Nabertherm). The heat treatment involves heating from room temperature to a pyrolysis temperature of 900°C, with a heating ramp of 5°C per minute, maintaining the pyrolysis temperature for 2 hours, and then cooling to room temperature. The pieces were recovered from the furnace, cleaned with isopropanol and water. deionized before being stored in an airtight container.

[0188] Biochar in the form of a plate (surface electrode)

[0189] The parts obtained directly from the above process are in the form of plates with dimensions of 37 mm x 13 mm x 2 mm.

[0190] Table 1 below illustrates the properties of the biochar formed: Specific surface area (m2 / g) Electrical resistivity (ohm.cm) 136 16x10 '

[0191] Biochar in the form of granules (volume electrode)

[0192] The biochar pieces obtained were mechanically cut using a cutter to form hexahedral biochar granules with dimensions of 3 mm x 3 mm x 2 mm. The biochar granules can also be obtained by first cutting the cedar wood pieces into aggregates before heat treatment. A shrinkage factor in the dimensions of the aggregates after heat treatment of approximately 1.3 must then be taken into account for cedar wood.

[0193] Example 2: manufacturing of the electrochemical reactor (first variant)

[0194] A reactor was designed using computer-aided design (CAD) software sold under the trade name “3D Fusion 360”, and the manufacturing of its various components was carried out by SLA 3D printing with a printer marketed under the reference “Form 2” by Formlabs. The printed components were cleaned and exposed to UV radiation. All components are made of polymethacrylate polymer material. The manufactured components are a main cylinder serving as a body and container, completed by a hollow cylindrical element functioning as an electrode separator and provided with grids at the ends for the circulation of liquids while ensuring the retention and compression of the biochar granules.Cap-shaped covers equipped with a copper current collector serve as pistons to compress the electrodes at the ends of the reactor, thus facilitating current recovery and connection to the external circuit, as well as the supply and discharge of the solution to be treated. [Fig.l] shows two schematic representations (Figures 1 a and 1 b) and a photo ([Fig.l] c) of the electrochemical reactor according to the invention, applied to the Galvano-Fenton process for the decontamination of effluents comprising organic pollutants.

[0195] The reactor 1 as manufactured comprises a first volume electrode of biochar granules 2, a second volume electrode of steel wool 3 electrically connected to the first volume electrode of biochar granules 2, at least one first inlet 4 and at least one first outlet 5, configured respectively to bring a liquid electrolyte in a continuous flow into the reactor, and to leave said liquid electrolyte in a continuous flow from the reactor in the same direction DF, and at least one separator 6 in the form of a hollow cylinder provided with grids at each of its ends. The separator 6 is made of dielectric material, it is in contact with said first and second electrodes (2, 3), it separates the first and second electrodes, it provides compression on the first and second electrodes, and it allows movement of the liquid electrolyte in a continuous flow from the first inlet 4 to the first outlet 5.

[0196] The reactor further comprises a piston cover containing a first copper current collector 7 in contact with the first volume electrode 2 and a piston cover containing a second copper current collector 8 in contact with the second volume electrode 3. The separator is a hollow cylinder with a length of 11 cm and a diameter of 13 mm. The hollow cylinder is provided at each end with a closing element comprising 2x1 mm openings spaced 0.5 mm apart such as a grid 9. The flow of liquid electrolyte DF is represented in [Fig.l] by a vertical arrow.

[0197] The final dimensions of the reactor are shown in Table 2 below: Parameter Value Radius (cm) 0.75 Height (cm) 17 Total reactor volume (ml) 30 Effective volume (mL) 19 % utilization 63 Spacer radius (cm) 0.65

[0198] Example 3: use of the electrochemical reactor for the decontamination of a model solution comprising malachite green

[0199] The reactor of the invention was used to implement the degradation of a model organic pollutant, malachite green (MG) with a flow rate of 10 mL.min 1 and a biochar / steel wool volume ratio of 5.03. The reactor was fed concomitantly at room temperature (25 °C) with an aqueous solution of MG and an aqueous solution of hydrogen peroxide, to form a liquid electrolyte having a pH 3 and comprising 10 ppm of MG (Co concentration) and 3 mM of hydrogen peroxide. The concentration of MG in the liquid electrolyte was evaluated at the reactor outlet for each condition, considering a pseudo-steady state of the operation. The configuration used in this first part of example 3 is shown in [Fig.2]. A degradation rate of 92% was obtained.

[0200] A complementary analysis was carried out during the parametric study, where a semi-continuous configuration was used in order to estimate the number of reactors in series necessary to achieve complete degradation of the model organic pollutant. In this configuration, 50 mL of a 10 ppm VM solution (solution to be treated with concentration Co) was treated in several steps or "passes" (named: r, 2r, 3r, Nr, etc...) through the reactor with a constant supply of an aqueous solution comprising 3 mM hydrogen peroxide at pH 3, at 25 °C, where each of these "passes" in the reactor would represent a reactor in a series configuration. At the end of each "pass" in the reactor, the VM concentration as well as the toxicity of the treated solution were evaluated. A flow rate of 50 mL.min 1 and a biochar electrode / steel wool electrode volume ratio of 2.78 were used.The configuration used in this second part of example 3 is shown in [Fig.3].

[0201] A degradation rate of 93% was obtained.

[0202] Comparative example 4: use of an electrochemical reactor in batch prior art for the decontamination of a model solution comprising malachite green

[0203] To do this, a batch configuration reactor (pyrex glass beaker marketed by Labbox equipped with a magnetic stirrer ensuring the mixing of the reagents) comprising 100 mL of a 10 ppm VM solution, a surface electrode in the form of a biochar plate as prepared in Example 1, and a surface electrode in the form of a commercial iron plate was designed. The current collector for each biochar and iron plate was made using a stainless steel wire (marketed under the reference "316L" by Goodfellow). The solution further comprises hydrogen peroxide having an initial concentration of 3 mM, it is at 25°C and has an initial pH of 3. The biochar electrode / iron electrode surface ratio is 3.

[0204] [Fig.4] shows a schematic representation of the batch configuration with surface electrodes of biochar and iron ([Fig.4] a), of the configuration of the invention, i.e. continuous flow reaction with volume electrodes of biochar and steel wool (LA) ([Fig.4] b), and a curve of the percentage of discoloration as a function of time for the batch configuration (curve a), [Fig.4] c) and for the configuration of the invention (curve b), [Fig.4] c).

[0205] It is observed that in the batch configuration, it takes 5 minutes to treat 100 mL of water to achieve 70% discoloration and more than 10 minutes to achieve 95% discoloration. On the other hand, with the reactor according to the invention (conditions from Example 3, Part 2: flow rate of 50 mL.min 1 and a biochar / steel wool volume ratio of 2.78), it takes only 2 minutes to treat the same amount of solution to 93% decolorization.

[0206] The reactor according to the invention has a more advantageous performance compared to the batch configuration: thanks to the use of volume electrodes, better degradation kinetics are observed, with an initial degradation rate of 700 pmol.L '.min *, which is 50 times higher than that obtained in batch configuration (14 pmol.L '.min '). These better kinetics of VM degradation allow a more rapid reduction in the toxicity of the treated solution.

[0207] In addition, an electrochemical characterization was carried out to compare the energy production performances of the Galvano-Fenton process in the two configurations: batch (not in accordance with the invention) and reactor (in accordance with the invention). The use of linear voltammetry allowed the characterization of the two configurations in order to obtain the power curves presented in [Fig.5]. It is observed that the power density expressed by the two configurations are similar.

[0208] Example 5: Use of the electrochemical reactor for the decontamination of model solutions comprising other types of organic pollutants

[0209] The reactor according to the invention was used in the degradation of four micropollutants of different chemical natures by the Galvano-Fenton process. The conditions chosen are those of Example 3, second part, namely a biochar electrode / steel wool electrode volume ratio of 2.78 and a flow rate of 50 mL.min '.

[0210] [Fig.6] shows the ratio of the concentration of the micropollutant solution at time t (concentration C) to the concentration of the micropollutant solution initially (at t = 0) (concentration Co), as a function of time when the micropollutant is atrazine (ATZ) ([Fig.6] a); alachlor (ALA) ([Fig.6] b), bisphenol A (BPA) ([Fig.6] c), and ethinylestradiol (EE2) ([Fig.6] d).

[0211] It can be observed, mainly for the most recalcitrant pollutants (ATZ and ALA), a degradation kinetics reaching a degradation of 80% and 96% after 20 minutes of treatment, and for the micropollutants that are easiest to degrade (BPA and EE2), a very rapid and practically complete degradation kinetics.

[0212] Example 6: design of the reactor according to the invention for applications other than the decontamination of effluents comprising organic pollutants

[0213] According to a first variant as defined in the invention (monobloc or mono-compartmental separator), the reactor is used for electrochlorination or as a supercapacitor and the electrically conductive material of the second electrode is a biosourced carbon. [Fig.7] shows the configuration of the reactor for electrochlorination ([Fig.7] a) and as a supercapacitor ([Fig.7] b).

[0214] More particularly, the liquid electrolyte enters the reactor 10 through the first inlet 40 in a direction DF, said first inlet 40 being positioned upstream of (i.e. before) the second current collector 80 and the liquid electrolyte leaves the reactor 10 through the first outlet 50 in the direction DF, said first outlet 50 being positioned downstream of (i.e. after) the first current collector 70. The liquid electrolyte then moves in a continuous flow from the first inlet 40 to the first outlet 50 in the direction DF, successively passing in this order through the second current collector 80, the second electrode 30, the separator 60, the first electrode 20, and the first current collector 70. In the case of electrochlorination, the following reaction takes place at the first electrode 20: 2H2O + 2e -> H2 + 2OH.In the case of electrochlorination, the following reactions take place at the second electrode 30: 2H2O -> O2 + 4 H+ + 4e, and 2C1 -> Cl2 + 2e\.

[0215] According to a second variant as defined in the invention (multi-compartment or multi-block separator), the reactor is used for the implementation of water electrolysis or as a redox flow battery, and the electrically conductive material of the second electrode is a bio-sourced carbon. [Fig.8] shows the configuration of the reactor for water electrolysis ([Fig.8] a) and as a redox flow battery ([Fig.8] b).

[0216] More particularly, a first liquid electrolyte enters the reactor 100 through the first inlet 41 in a direction DN, said first inlet 41 being positioned upstream of (i.e. before) the second current collector 80 and the first liquid electrolyte leaves the reactor 100 through the first outlet 51 in a direction D FF perpendicular to the direction D| h, said first outlet 51 being positioned downstream of (i.e. after) the second electrode 30, perpendicular to the first inlet 41 and at the level of a first compartment 61 of the separator 6. The first liquid electrolyte then moves in a continuous flow from the first inlet 41 to the first outlet 51 in a direction D| h then a direction DFF, successively passing in this order through the second current collector 80, the second electrode 30 and the first compartment 61 of the separator 6.

[0217] The reactor further comprises a second inlet 42 and a second outlet 52 such that a second liquid electrolyte enters the reactor 100 through the second inlet in a direction DF2, said second inlet 42 being positioned upstream of (i.e. before) the first current collector 70 and the second liquid electrolyte leaves the reactor 100 through the second outlet 52 in a direction DF2 perpendicular to the direction DF2, said second outlet 52 being positioned downstream of (i.e. after) the first electrode 20, perpendicular to the second inlet 42 and at the level of a second compartment 62 of the separator 6. The second electrolyte liquid then moves in a continuous flow from the second inlet 42 to the second outlet 52 in a direction DF2, then a direction DF2, successively crossing in this order the first current collector 70, the first electrode 20 and the second compartment 62 of the separator 6.

[0218] The first and second compartments (61, 62) are separated by an ion exchange membrane 11. This ensures ionic continuity within the reactor. The method makes it possible to transform water into dioxygen and dihydrogen in the case of water electrolysis, or vanadium ions V5+ and V2+ into vanadium ions V4+ and V3+ respectively in the case of the redox flow battery.

[0219] In [Fig.9], the reactor 101 is identical to that of [Fig.8] except with regard to the separator 6 which further comprises a third compartment 63 interposed between the first and second compartments (61, 62) so that the first and third compartments (61, 63) are separated by an ion exchange membrane such as a cationic membrane 12, and the second and third compartments (62, 63) are separated by an ion exchange membrane such as an anionic membrane 13.The reactor 101 further comprises a third inlet 43 and a third outlet 53, such that a third liquid electrolyte enters the reactor 101 through the third inlet 43 in a direction DF3, said third inlet 43 being positioned at the third compartment 63 of the separator 6, and the third liquid electrolyte leaves the reactor 101 through the third outlet 53 in the direction DF3, said third outlet 53 being positioned at the third compartment 63 of the separator 6. The third liquid electrolyte then moves in a continuous flow from the third inlet 43 to the third outlet 53 in a direction DF3, passing through the third compartment 63 of the separator 6.

[0220] According to this [Fig.9], the reactor is a reactor for implementing desalination of sea water, or for producing electrical energy from osmotic energy and salt water, and the electrically conductive material of the second electrode is a biosourced carbon.

Claims

Claims

1. Fixed bed flow electrochemical reactor, characterized in that it comprises: - at least one first volume electrode comprising an electrically conductive material, preferably a biosourced carbon, - at least one second surface or volume electrode comprising an electrically conductive material, the second electrode being electrically connected to said first electrode, - at least one first inlet and at least one first outlet, configured respectively to bring a liquid electrolyte in continuous flow into the reactor, and to leave said liquid electrolyte in continuous flow from the reactor, and - at least one separator comprising at least one dielectric part in contact with said first and second electrodes, said separator being configured to separate the first and second electrodes, to ensure compression on said first electrode,and to allow movement of the liquid electrolyte in a continuous flow from the first inlet to the first outlet.,

2. Reactor according to claim 1, characterized in that the separator is a rigid separator, preferably having a Young's modulus of at least 1.5 GPa, and particularly preferably of at most 250 GPa.

3. Reactor according to claim 1 or 2, characterized in that the second electrode is a volume electrode, and in that the first electrode has a volume VI and the second electrode has a volume V2 so that V1 / V2 ranges from 1 to 100.

4. Reactor according to any one of the preceding claims, characterized in that the dielectric part of the separator comprises at least one polymer material, preferably chosen from polyamides, polycarbonates, polyetherimides, polyolefins, polystyrenes, polyacrylates, polymethacrylates, polyaryletherketones, and one of their mixtures.

5. Reactor according to any one of the preceding claims, characterized in that the first electrode has a mass volume ranging from 0.1 to 10 cmVg, preferably from 2.5 to 5.0 cmVg, and particularly preferably from 3.0 to 4.5 cmVg.

6. Reactor according to any one of the preceding claims, characterized in that the reactor comprises at least one configured means to obtain a movement of the liquid electrolyte in continuous flow within said reactor with a flow rate ranging from 0.1 to 5*108 ml / min, and preferably ranging from 1 to 2.5*107 ml / min

7. Reactor according to any one of the preceding claims, characterized in that the separator is a hollow element provided with at least one closing element having one or more openings, to allow the continuous flow movement of the liquid electrolyte from the first electrode or the second electrode towards the first outlet.

8. Reactor according to any one of the preceding claims, characterized in that the electrically conductive material of the first electrode is a biosourced carbon in the form of granules, chips, or pellets, preferably of average size ranging from 250 μm to 100 mm.

9. Reactor according to any one of the preceding claims, characterized in that the electrically conductive material of the second electrode is chosen from ferrous waste, iron, iron alloys, bio-sourced carbon, and one of their mixtures.

10. Use of an electrochemical reactor as defined in any one of claims 1 to 9, for depolluting a liquid medium comprising at least one organic pollutant, for disinfecting water by electrochlorination, for carrying out the electrolysis of water, for carrying out desalination of seawater, for energy storage, or for the production of electrical energy from osmotic energy.

11. Method for decontaminating a liquid medium comprising at least one organic pollutant, preferably chosen from industrial effluents, wastewater, used oil emulsions, and oil-laden wastewater emulsions, comprising at least one organic pollutant, characterized in that: - said method comprises at least one step of degrading said organic pollutant in an oxidizing medium generated by the use of an electrochemical reactor as defined in any one of claims 1 to 9 wherein: - the liquid electrolyte comprises said liquid medium and at least one oxidizing agent, and - the electrically conductive material of the first electrode is a biosourced carbon, and the electrically conductive material of the second electrode is chosen from iron, ferrous waste and iron alloys.

12. Method according to claim 11, characterized in that the organic pollutant is chosen from plasticizers, herbicides, pesticides, endocrine disruptors, pharmaceutical products, perfluorocarbons, fungicides, and one of their mixtures.

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