WO2010037717A1

WO2010037717A1 - Device, use thereof and process for removing a compound contained in a fluid

Info

Publication number: WO2010037717A1
Application number: PCT/EP2009/062541
Authority: WO
Inventors: Luc Schrive; Jean-Christophe Ruiz; Bruno Fournel
Original assignee: Commissariat A L'energie Atomique
Priority date: 2008-09-30
Filing date: 2009-09-28
Publication date: 2010-04-08
Also published as: FR2936509A1; FR2936509B1

Abstract

The present invention relates to a device for removing at least one compound contained in a fluid, comprising a UV radiation system, at least one first compartment containing a photocatalytic material capable of being irradiated by said UV radiation system, means suitable for conveying said fluid into said at least one first compartment, at least one second compartment different from said at least one first compartment, suitable for recovering said fluid after removal of said compound, means for conveying a fluid containing oxygen into at least one second compartment and a membrane that separates said first and second compartments and is suitable for the passage of at least one fluid. The present invention also relates to a process for removing at least one compound contained in a fluid using such a device.

Description

DEVICE, USE THEREOF AND METHOD FOR REMOVING A COMPOUND CONTAINED IN A FLUID

DESCRIPTION

TECHNICAL AREA

The invention belongs to the field of depollution, disinfection, purification and / or decontamination of fluids.

Thus, the present invention provides a photocatalytic membrane reactor type device for purifying a particularly aqueous stream contaminated with an undesired compound such as a toxic compound. Such a device can be easily adapted to the scale of the laboratory as on an industrial scale.

The present invention also relates to a method for eliminating an undesired compound contained in a fluid implementing such a device.

STATE OF THE PRIOR ART The destruction of organic pollutant compounds is carried out (i) by a chemical treatment such as chemical oxidation in the presence of oxidants

(H2O2, NaOCl) or by acid or basic hydrolysis, (ii) by a physical treatment using UV radiation by mercury lamp, (iii) by a biological treatment such as biological oxidation carried out in effluent treatment plants or (iv) by a combination of several types selected from chemical, physical and biological treatments. Disinfection of fluids such as air and water can be achieved directly by UV radiation [1, 2]. This system has already been used on an industrial scale for many years [3]. Around a wavelength of

254 nm (UV C) [4], DNA microorganisms and more generally any living cell is degraded, irreparably, preventing the duplication of genetic heritage and thus cell division. This results in mortality of the cell population or microorganisms.

UV can also have indirect effects in the presence of photocatalytic materials. Indeed, other emission lines can have lethal effects on living microorganisms. A mercury lamp emitting at 365 nm (UV A) has the property of exciting titanium oxide (TiO ₂ ) in crystalline anatase phase or any other photocatalytic compound, usually semiconductors such as SiO 2, ZrO 2, etc. leading to the formation of free radicals such as the hydroxyl radical (OH °).

The desired effect is usually an oxidation of pollutants. From a polluted effluent, the result will be a decrease in the chemical oxygen demand (COD).

In summary, the reaction species are: free radicals that play the set of reaction initiators, polluting compounds and oxygen. The products of the reaction, in the case of a simplifying hypothesis where the pollutant is a hydrocarbon are mainly water (H ₂ O) and carbon dioxide (CO2) • TiO ₂ or any other photocatalytic material acts as a reaction catalyst, activated by the energy of UV photons [5], the whole producing free radicals.

Concerning the photocatalytic material, it is important that it has adsorption properties of the compounds to be destroyed [6] in order to increase the probability of encounter between, on the one hand, the free radicals formed on the surface of the photocatalytic material. and whose life is very low and, secondly, pollutants to oxidize.

The presence of free radicals in particular 0H ° and the importance of the presence of dissolved oxygen has been demonstrated by [7]. Hydrogen peroxide can also be used [8]. We then speak indistinctly of oxidation reactions or hydrolysis.

The targeted pollutants are usually organic compounds in dissolved form, in the form of colloids, aggregates of organic matter, or microorganisms. In the latter case, the oxidation phenomena are initiated on the surface of the microorganism. The wall of the microorganism is injured and can lead to lysis and death of the microorganism.

Some studies have also highlighted the possibility of agglomerating heavy metals, or halogenated compounds in solution, by oxidation or reduction reactions [9]. In some cases, the separation of these aggregated compounds is then facilitated. This technology therefore eliminates pathogenic compounds, chemical (pollutants such as phenols, insecticides, pesticides, heavy metals) or biological origin (toxins, viruses, bacteria, yeasts, molds, protozoa, etc.). disinfection (chemical or biological) of water.

Currently, the most common UV emission device consists of a mercury vapor lamp in the form of a "neon" type tube sealingly inserted into a pipe. The fluid film (liquid or gas) surrounding the lamp undergoes UV irradiation causing the death of microorganisms that are suspended there. The disadvantage of conventional mercury lamps is their large size, the need for a heating period at startup, and especially their limited life (about a year) producing industrial waste contaminated with mercury.

It is also possible to emit UV radiation by light-emitting diodes (LEDs) having a broad emission spectrum (typically 240 to 400 nm). The advantage of this type of component is their low cost, low energy consumption (of the order of tens of milliwatts) and their small size allowing their implantation as close as possible, or even inside a vein liquid and this even for small piping cut. In addition, their lifespan is 5 to 10 times longer than that of mercury lamps.

At present, the implantation of LEDs on any type of surface is developed by PW Circuits based in England. This company has devised the concept of tubular photocatalytic reactor of large diameter (Φ 80-100 mm) equipped with LEDs described in the international application WO 2007/113537 [10]. LEDs can be inserted in all kinds of systems intended for the degradation of compounds contained in fluids, for example air [11], or water [12]. LEDs also have the characteristic of emitting a relatively focused radiation, that is to say that the light beam is limited to an angle of a few degrees, typically 10 to 50. To increase the probability of encounter between the beam and the reagents, it may be chosen to multiply the scattering of the LEDs around the liquid vein as described in the international application WO 2007/113537 [10].

The photocatalytic material may be in the form of a layer deposited on a support (for example a pipe), or on a porous support [13]. The fact of depositing a photocatalytic layer on the surface of a pipe simplifies the control of the process because there is no need for a catalyst recovery step for recycling. But the disadvantage lies in the limited probability of encounter between species reaction, namely the free radicals formed on the surface of the photocatalytic material, the oxygen and the compounds that are to be destroyed.

We can then favor the implementation of a photocatalytic material in dispersed form. For example, a TiO 2 powder whose particle size is less than or equal to one micrometer is kept in suspension by sufficient agitation or turbulence, in the presence of a UV irradiation system immersed in or located at the outside the reactor in the case where it has transparent walls.

Classically, at the end of the reaction, the particles are recovered. There is therefore a juxtaposition of a reaction step and a separation step. This recovery can be done by a decantation step. Nevertheless, the small grain size of the particles limits this possibility. A membrane filtration separation step juxtaposed with the reaction step ([14]) is then advantageously preferred.

The membranes used may be of the hollow fiber type, or cylindrical (or any other membrane geometry), organic or inorganic materials, for example ceramic type (or any other porous material). However, it is important to take into account the abrasive properties of the photocatalytic particles in the form of metal oxides or any other semiconductor material, and it will be preferred to use ceramic membranes. In some cases, the photocatalyst is immobilized on the membrane [15]. However, in such a device, there is no diffusion of oxygen in the photocatalytic reactor.

Although different types of fluid decontamination devices are currently available, there is still a real need to provide a device to improve the probability of meeting pollutants, reagents such as oxygen and activated photocatalyst, while remaining compact. way to present a low cost of production.

DISCLOSURE OF THE INVENTION The present invention makes it possible, inter alia, to meet the needs indicated above and to solve the drawbacks of the devices that are useful in the photocatalytic oxidation of the fluids of the prior art. For this purpose, the present invention is based on a simplified device and improved with respect to prior art fluid treatment devices. This device can be defined as a membrane photocatalytic reactor irradiated with UV. Indeed, the steps of:

retention of the photocatalytic powder,

- oxidation and / or hydrolysis reaction,

- diffusion of oxygen,

- Separation of oxidized products takes place in one place, at the level of the membrane surface. It is therefore the membrane, specific element membrane photocatalytic reactor which provides, in one place, the various features described.

The device according to the present invention makes it possible to increase the probability of encounter between the compound (s) to be eliminated, the reagents such as in particular oxygen and the activated photocatalyst.

This amounts to increasing the ratio

"Active area / volume device". By "active surface" is meant, in the context of the present invention, the surface of the photocatalyst activated by UV photons.

Ultimately, this amounts to improving the compactness of the device, an objective in line with the small size of usable UV radiation systems such as UV LEDs and the focusing of their light beam.

The compactness of the system reduces the volume of the device and therefore its size, to reduce the size of the associated hydraulic system (piping, pumps), and thus reduces construction costs. At the laboratory scale, a better manipulation of the system is obtained.

Thus, the present invention provides a device for removing at least one compound contained in a fluid, comprising

a system of UV radiation, at least a first compartment called "compartment Ci" containing a material photocatalytic capable of being insolated by said UV radiation system,

means adapted to bring said fluid into said at least one first compartment (compartment Ci), at least one second compartment said to

"Compartment C ₂ " distinct from said at least one first compartment (compartment Ci), adapted to recover said fluid after removal of said compound, - means adapted to bring an oxygen-containing fluid into at least one second compartment (compartment C2) ,

a membrane separating said first and second compartments (compartments Ci and C2) and adapted to the passage of at least one fluid.

In the context of the present invention, the terms "first compartment" or "compartment Ci" are equivalent and can be used interchangeably. The same applies to the terms "second compartment" or "compartment C ₂ ".

In the context of the present invention, the term "compound" means an undesired compound such as an impurity or a contaminant, likely to be present or present in a fluid. Advantageously, said compound is a pathogenic compound.

The compound may be an organic or inorganic, molecular or particulate compound. Said organic compound may be present in the fluid under dissolved form, in the form of colloids, in the form of aggregates of organic matter.

The compound may be of biological origin such as a toxin, a mold, a microorganism, a virus, a bacterium, a yeast, a protozoan or a fungus.

The compound may be of chemical origin and in particular chosen from NO2, CO, a phenol, an insecticide, a pesticide, a volatile organic compound such as benzene, toluene, ethylbenzene or xylenes, an aldehyde, a halogen compound or heavy metal.

The compound may be present in the fluid in very dilute or much more concentrated form. Thus, the amount of said compound in the fluid to be treated is between 1 μg and 100 g / liter of fluid to be treated.

In the context of the present invention, the term "fluid" means a gas or a liquid.

By way of examples of fluids in which the present invention aims to eliminate undesired compounds, mention may be made of wastewater, in particular in purification plants, swimming pool water, aquarium water, cooling water of air conditioning systems, air from air-cooled towers, air circulating in hospitals, air circulating in companies in which the presence of pollutants or impurities is not acceptable vis-à-vis production such as pharmaceutical or agri-food companies. More In general, the present invention relates to a device and a method applicable to any gaseous or liquid fluid in which at least one compound is to be removed.

In the context of the present invention, the term "removal of a compound in a fluid" means both reducing the amount of the compound in said fluid and completely removing said compound in said fluid.

This elimination can be accomplished by transforming said compound into another preferred compound as less pathogenic and / or inactivating said compound and in particular compounds of biological origin. In the case of a toxic compound, its elimination consists of inactivating it and / or transforming it into a compound that is harmless to human and / or animal health. The removal of the compound in the context of the present invention implements a photocatalytic degradation.

The membrane allowing the passage of at least one fluid present in the device of the invention is a porous membrane, mineral or prepared from organic compounds which, as previously explained, has different functions.

A membrane prepared from organic compounds may be cellulose acetate, ethylcellulose, polyether sulfone or polyacrylonitrile, while an inorganic inorganic membrane will advantageously be ceramic, metal or inert carbon such as, for example, Carbosep® membranes.

It separates, from the second compartment (s) (compartment (s) C2), the (or) first compartment (s) (compartment (s) Ci) in which (s) the oxidation and / or hydrolysis reaction and thus the formation of free radicals.

In addition, it allows the passage of the oxygen from the second compartment (compartment C2) to the first compartment (compartment C1) and the recovery of the treated fluid in the second compartment (compartment C2) • By "treated fluid" is meant, in the context of the present invention, a fluid in which the compound to be removed is no longer present or in which the compound to be removed is present in an oxidized form and / or hydrolysed, ie a form rendered harmless.

Finally, it can support and / or retain the photocatalytic material during the duration of the oxidation and hydrolysis reactions. The retention of the photocatalytic material may be carried out for recycling said material.

Advantageously, said membrane is chosen from microfiltration membranes, ultrafiltration membranes, nanofiltration membranes and reverse osmosis membranes.

The person skilled in the art will be able to choose, from among the membranes above, the membrane that is best adapted according to the nature and the size of the compound to be eliminated, the nature and the particle size of the catalytic material, the nature and flow rate of the fluid to be treated, ...

It should be noted that in the case where the device according to the present invention comprises different second compartments (compartments C2), each second compartment (compartment C2) is separated from the first compartment (compartment Ci) by a membrane. Similarly, for a device according to the present invention comprising different first compartments (Ci compartments), each first compartment (compartment Ci) is separated from the second compartment (compartment C2) by a membrane. In such devices, the membranes may be of the same or different nature. Thus, the membranes mainly used for separating and retaining the photocatalytic material are advantageously of the microfiltration or ultrafiltration type, defined by pore sizes smaller than the average particle size of the photocatalytic material, typically of the order of one micrometer up to about ten nanometers.

Similarly, the membranes useful for diffusing the oxygen of a second compartment (compartment C2 rich in gas such as air or oxygen) to the first compartment (compartment Ci) filled with liquid and poor in oxygen. The consumption of this reagent by the oxidation reactions is advantageously hydrophilic or hydrophobic membranes, of the nanofiltration, ultrafiltration or microfiltration type. Finally, for membranes allowing the treated fluid (or permeate) to flow and retaining the photocatalytic material and the compounds to be removed, the latter are advantageously of the ultrafiltration, nanofiltration or even reverse osmosis type, that is to say the membranes of which the pores are of the order of a few tens of nanometers up to the nanometer, or even dense membranes.

The membrane of the device according to the invention can be of any form provided that this form allows the separation of the first (s) and second (s) compartments (compartments Ci and C2). In the particular embodiments of the device according to the invention which will be presented hereinafter, the membrane of the device according to the invention is: either of substantially flat shape, in particular of substantially flat circular shape and in particular a circular membrane comprising a surface of the order of a few cm ² , typically between 15 to 100 cm ² ; is of cylindrical shape and in particular in cylindrical form of substantially circular outer cross section.

Any UV radiation system can be used in the context of the device according to the present invention. By "UV radiation system" is meant a system capable of emitting radiation whose wavelength range is in the near ultraviolet range. A mercury vapor lamp in the form of a "neon" type tube, a sodium vapor lamp or a light emitting diode (LED).

Advantageously, the UV radiation system implemented in the context of the device according to the invention comprises at least one LED.

In a first variant of the device according to the present invention, said UV radiation system comprises at least two LEDs connected in series, in particular at least 5 LEDs, in particular at least 10 LEDs and, more particularly, at least 50 LEDs mounted in series, said UV radiation system may include up to several hundred LEDs in series.

In a second variant of the device according to the present invention, said UV radiation system comprises at least two LEDs connected in parallel, in particular at least 5 LEDs, in particular at least 10 LEDs and, more particularly, at least 50 LEDs connected in parallel, said UV radiation system may include up to several hundred LEDs mounted in parallel.

In a third variant of the device according to the present invention, said UV radiation system comprises LEDs mounted in series and LEDs connected in parallel.

The skilled person will determine without inventive effort the number of LEDs to use in particular depending on the size of the device.

In addition, the UV radiation system can be located anywhere on or in the device according to the present invention with the sole condition of ability to effectively irradiate the photocatalytic material. Thus, the UV radiation system can be located on the outer wall of the device, on the inner wall of the device, on the membrane separating the first compartment (compartment Ci) from a second compartment (compartment C2), inside the first compartment (compartment Ci) especially in the form of garlands and / or inside the second compartment (compartment C2) especially in the form of garlands.

It is clear that the device according to the present invention has means for the power supply of said UV radiation system such as electrical connections.

Any type of photocatalytic material can be used in the context of the present invention. Advantageously, the photocatalytic material used in the context of the present invention consists of semiconductor particles.

In the context of the present invention, the term "semiconductor" means a material having an electrical conductivity intermediate between the metals and the insulators. The conductivity properties of a semiconductor are influenced mainly by the charge carriers (electrons or electronic vacancies) that the semiconductor exhibits. These properties are determined by two particular energy bands called the "valence band" (corresponding to the electrons involved in the covalent bonds) and the "conduction band" (corresponding to the electrons in an excited state and able to move in the semiconductor). The gap represents the difference in energy between the valence band and the conduction band. Thus, the semiconductor may be chosen from the group consisting of:

a metal oxide such as TiO 2, WO ₃ , ZnO, SnO ₂ , SrTiO ₃ , Fe ₂ O ₃ , Ta ₂ O ₅ or a mixture of different metal oxides; a metal sulphide such as CdS,

ZnS, WS ₂ or a mixture of different metal sulfides; other semiconductors such as GaAs, GaP, CdSe, SiC or a mixture thereof;

- and their mixtures.

More particularly advantageously, the semiconductor implemented in the context of the present invention is a metal oxide and in particular a metal oxide from the list previously given, or a mixture of metal oxides.

The particle size of the photocatalytic material is advantageously less than 10 μm, especially less than 5 μm, in particular between 2 μm and 2 nm, and more particularly between 1 μm and 10 nm.

In a first variant of the invention, the photocatalytic material is in the form of a deposit. The term "depot" in the present invention is synonymous with a layer, a film, a coating.

In this variant, the photocatalytic material is deposited in the form of a layer or film on the membrane which separates the first compartment (compartment Ci) from a second compartment (compartment C2). In this variant, given the very short duration free radicals (a few nanoseconds), the oxidation and / or hydrolysis reaction is preferably carried out at the inlet of each porous membrane pore where the probability of meeting between reagents (free radicals produced by the radiation UV at the surface of the pore, compounds to be eliminated near the entrance of the pore, dissolved oxygen) is the largest.

In addition to this first advantage (close contact between reactive species, separation of products, retention of the catalyst in dispersed form, diffusion of oxygen), the membrane will have regenerating or self-releasing properties. This is particularly interesting when the fluid to be treated contains organic species and microorganisms. It is then formed on the surface of the membrane, a layer of biofilm difficult to clean. UV photocatalysis will then prevent the formation of this biofilm. This effect already described in the patent application JP2002001332 [16] works in this document using membranes immersed in the entire reactor illuminated by mercury lamps. This phenomenon can be achieved by LEDs located closest to the membrane surface. This increases the possibility of destroying the deposition layer and improves the decolouring effects. The photocatalytic material used in this first variant of the present invention is achievable by various techniques known to those skilled in the art such as the sol-gel technique, the synthesis under pressure of CO2 or the hydrothermal synthesis followed by sintering, the vapor phase deposition (MOCVD), the deposition of preformed nanometric or micrometric particles then deposited under hydrostatic pressure and then sintered. In these different techniques, the sintering step makes it possible to bond the particles and the layer thus formed to the support which supports said layer.

The film or the layer of semiconductor particles advantageously has a thickness of between 0.01 and 20 μm and in particular between 1 and 10 μm. This thickness is either substantially constant or variable on the deposition surface.

In a second variant of the invention, the photocatalytic material is in dispersed form. The dispersion of the photocatalytic material makes it possible to increase the accessible surface area of the material for the reaction.

The photocatalytic material used in this second variant of the present invention is feasible by various techniques known to those skilled in the art such as by a sol-gel technique, by supercritical CO2 synthesis, by hydrothermal synthesis, by MOCVD or by any other technique that makes it possible to obtain grains comprising micropores or consisting of nanoparticles with photocatalytic functionality.

In this second variant, the particles are introduced into the fluid to be treated before, after and / or during the introduction of the latter into the device according to the invention. The particles are present in the fluid to be treated in an amount of between 10 ² and 10 ⁹ particles / ml, in particular between 10 ³ and 10 ⁶ particles / ml of fluid to be treated.

In a third variant of the invention, the photocatalytic material is both in the form of a deposit and in dispersed form. This variant makes it possible to cumulate the advantages related to these two forms of presentation.

According to a particular embodiment, the device of the present invention comprises a single second compartment (compartment C2)

In a first variant of this particular embodiment, the device comprises a first compartment (compartment Ci) and a second compartment (compartment C2), separated by a membrane as previously defined.

In a second variant of this particular embodiment, the device comprises at least two first compartments (Ci compartments).

Advantageously, said device comprises between 2 and 500 first compartments, especially between 5 and 100 first compartments. Each first compartment

(compartment Ci) is separated from the second compartment

(compartment C2) by a membrane as previously defined.

The ratio "Volume of the first compartment (s) / volume of the second compartment" may be between 1/100 and 100/1, in particular between 1/50 and 50/1, in particular between 1 / 10 and 10/1 and, more particularly, between 1/2 and 2/1. At the spatial organization level, the first compartment (s) (compartment (s) Ci) can be included in the second compartment (compartment C2), the second compartment (compartment C2 ) can be included in the first compartment (compartment Ci) or the first (s) and second compartments (compartments Ci and C2) can be arranged one on the other or side by side.

The second compartment (compartment C2) is adapted, on the one hand, to diffuse the oxygen supplied to the latter by an oxygen-containing fluid and, on the other hand, to recover the treated fluid. These two functions are exercised by compartment C2 sequentially.

According to another particular embodiment, the device of the present invention comprises at least two second compartments

(compartments C2) Advantageously, said device comprises between 2 and 500 compartments C2, in particular between 5 and 100 compartments C2. Every second compartment (compartment C2) is separated from the first compartment (compartment Ci) by a membrane as previously defined.

In this embodiment, at least one of the second compartments (compartments C2) is adapted to recover the treated fluid and at least one of the second compartments (compartments C2) is adapted to diffuse the oxygen supplied into this compartment by the fluid containing oxygen. The ratio "Volume of the first compartment / Volume of the second compartments" can be between 1/100 and 100/1, in particular between 1/40 and 40/1, in particular between 1/8 and 8/1 and, more particularly, between 1/2 and 2/1. At the level of spatial organization, the second compartments

(compartments C2) may be included in the first compartment (compartment Ci) and / or be located on the periphery of the first compartment (compartment Ci) and in direct contact therewith.

The device according to the present invention also comprises means adapted to bring the fluid to be treated in said (or said) first compartment (s) (compartment (s) Ci), means adapted to recover this fluid at the output of said ( or said first compartment (s) (compartment (s) Ci), means adapted to recover the permeate (ie the treated fluid, recovered in at least a second compartment (compartment C2) after it has passed through the membrane separating the first compartment (compartment Ci) containing the fluid to be treated and this second compartment (compartment C2)) and means adapted to bring an oxygen-containing fluid into at least one second compartment (compartment C2)

In the context of the present invention, the term "oxygen-containing fluid" means a gaseous fluid containing oxygen. The oxygen is present in said fluid in an amount of between 5 and 100% (vol / vol), in particular between 10 and 90% (vol / vol) and, in particular, between 20 and 80% (vol / vol) of the fluid containing oxygen. Said fluid is more particularly ambient air or pure or substantially pure oxygen.

Any means for bringing a liquid or gaseous fluid into a compartment is usable in the context of the present invention. Among these means include liquid supply pumps, gas supply pumps, liquid supply means by hydrostatic pressure. These means are connected to the compartments Ci or C2 by a pipe made of flexible material or rigid material.

The present invention also relates to the use of a device as previously defined for removing at least one compound contained in a fluid. Advantageously, said compound is a pathogenic compound and, in particular as previously described.

The present invention finally relates to a method for removing a compound contained in a fluid (AT) . The method according to the present invention comprises the steps of: a) introducing said fluid (A) into a first compartment (compartment Ci) of a device as previously defined; b) introducing oxygen into said first compartment (compartment Ci) from at least one second compartment (compartment C2) separated from said first compartment (compartment Ci) by a membrane as previously defined; c) irradiating a photocatalytic material as previously defined and present in said first compartment (compartment Ci) with a UV radiation system as previously defined; d) recovering a fluid (B) no longer comprising said compound in at least one second compartment (compartment C2)

Step (a) of the method according to the present invention can implement means for supplying a fluid as previously defined.

The introduction of the fluid (A) into the first compartment (compartment Ci) can be done at very variable flow rates. As examples, when the device is in the range of laboratory equipment, this flow can be of the order of 0.1 to

100 1 / h and in particular of the order of 1 to 10 1 / h. When the device is in the range of pilot-type or industrial production devices, this flow rate may be of the order of 10 to 10 ⁵ 1 / h and in particular of the order of 100 to 10 ⁴ 1 / h.

The fluid (A) is recovered at the outlet of the first compartment (compartment Ci) by any means and at any flow adapted and selected according to the operating conditions used for the introduction of the fluid (A). Once the fluid (A) recovered, it can be subjected to at least one new treatment according to the method of the invention.

Step (b) of the process according to the present invention consists in introducing, into one (or more) first compartment (s) (compartment (s) Ci), an oxygen-containing fluid from a second compartment (compartment C2) separated from said (or said) first compartment (s) (compartment (s) Ci) by a membrane as defined above.

The step is to introduce, in the (or) first compartment (s) (compartment (s) Ci) where the oxidation and / or hydrolysis reaction takes place, one of the reagents involved in this reaction. what is oxygen? Thus, the second compartment (compartment C2) is a compartment rich in a fluid containing oxide and in particular a gaseous fluid such as air or oxygen, whereas the first compartment (s) ) (compartment (s) Ci) is (are) filled with liquid and poor (s) in oxygen due to the consumption of this reagent by photocatalytic oxidation reactions. The introduction of oxygen is in the most dispersed form possible, in the form of microbubbles obtained by convection, for example, under the effect of a pressure difference or in molecular form by a diffusion phenomenon, under the effect of the difference of the chemical potential. The introduction of oxygen into the first compartment (s) (compartment (s) Ci) can be done at a flow rate at most equal to the rate of introduction of the fluid (A), in particular minimum equal to l / 10000 ^-th of the fluid flow (A), especially between l / 10 and l ^-th / 1000 ^-th of fluid flow (A).

Step (b) of the process according to the invention is carried out following a preliminary step of introducing, into the second compartment (compartment C2), an oxygen-containing fluid which can be done at a substantially equivalent flow rate. the rate of introduction of oxygen into the first compartment (s) (compartment (s) Ci).

Step (c) of the process according to the invention consists in irradiating the photocatalytic material with UV radiation. This irradiation has the effect of activating the photocatalytic material on the surface of which charges (electrons and vacancies) are created, said charges being at the base of the elimination reactions of the compound contained in the fluid to be treated.

The exposure of the photocatalytic material during step (c) of the process according to the invention may be continuous or periodic. The specific energy of this insolation is included on average, when said UV radiation system comprises at least one LED, between 0.01 and 100 mW / cm ² and in particular between 0.1 and 20 mW / cm ² at a wavelength of between 254 and 380 nm.

The last step of the process according to the present invention i.e. step (d) is to recover the treated fluid also referred to as fluid (B) or permeate. This step is performed by draining the treated fluid from (or) first compartment (s) (compartment (s) Ci) to at least a second compartment (compartment C2) through the membrane separating these compartments.

This step can be carried out continuously during the reaction or sequentially by alternating oxygen diffusion times and permeate drainage moments, as explained below. In this case, the membrane retains the catalyst, but passes the oxidized compounds and / or hydrolyses in the case where they have a lower molecular weight than the initial compounds to eliminate and can pass through pores of the membrane. A treated fluid, also referred to herein as "a cleansed permeate", is then collected. The passage of the liquid (B) treated (ie the liquid after implementation of steps (a) to (c) of the process according to the invention), through the membrane, from a first compartment (compartment Ci) to a second compartment (compartment C2), and its recovery can be done by simple gravity, using a compressed gas, stirring, suction. In a first embodiment of the present invention, the second compartment

(compartment C2) of step (b) of the method is the same as that of step (d) of the method and steps (b) and (d) are performed sequentially.

In a second embodiment of the present invention, the second compartment (compartment C2) of step (b) of the process is distinct from the compartment of step (d) of the method and steps (b) and d) may be performed continuously during the process.

The process of the present invention is remarkable because it makes it possible to associate two distinct steps (reaction and then separation of the photocatalyst) of the process. More generally, the device according to the invention makes it possible to couple, in one and the same place, the membrane surface, the steps of the process for removing a compound contained in a fluid which are the oxidation reaction stages and / or hydrolysis, retention of photocatalytic material, diffusion of oxygen, and drainage of oxidized and / or hydrolyzed compounds. It should be remembered that the step of retaining the catalytic material is necessary when the latter is in the form of dispersed particles and can be carried out during step (d) of the process or following step (d) of process for recycling these particles. BRIEF DESCRIPTION OF THE DRAWINGS

Figure 1 is a schematic representation of a device according to the invention. FIG. 1A is a representation of a device with a first compartment (compartment Ci) and a second compartment (compartment C2) with the means and additional elements allowing the implementation of the method according to the invention. FIG. 1B is a detailed representation of a part of the device and, more particularly, of the first compartment (compartment C1) with the substantially flat membrane with photocatalytic layer on its surface (fi), the circuit of the fluid path (A) and the UV LEDs positioned above the first compartment (compartment Ci). FIG. 2 presents a schematic representation of a tubular membrane with an internal photocatalytic layer having a "garland" of UV LEDs positioned in the middle of the liquid vein. The first compartment (compartment Ci) corresponds, in this case, to the interior space of the tubular membrane and the second compartment (compartment C2) not materialized to the space located at the periphery of the tubular membrane.

FIG. 3 shows a schematic representation of a device according to the present invention in the form of a housing serving as an industrial membrane photocatalytic reactor with mounting of external LEDs.

FIG. 4 is a schematic representation of a device according to the present invention in the form of a housing serving as a reactor industrial photocatalytic membrane with external LEDs (at the periphery of the housing) and internal LEDs (in strings inserted inside the membrane door).

DETAILED PRESENTATION OF PARTICULAR EMBODIMENTS

The present invention provides an apparatus allowing the implementation of oxidation and / or hydrolysis reactions on a laboratory scale (treatment of a few milliliters to a few liters per hour), easily extensible to larger sizes, up to industrial type devices (several m ³ or tens of m ³ per hour).

1. Device to a second compartment

(compartment C ₂ ):

1.1. Device of Figure 1: A device according to the present invention is proposed adapted for use in the laboratory and based on the implementation of a housing (or membrane door) containing a substantially flat membrane whose surface is of the order of a few cm ² (typically 15 to 100 cm ² ) for example.

The casing used is advantageously a filter casing in frontal or tangential mode manufactured by the company Millipore or the company TAMI industries (France).

The membrane (1) used is an advantageously organic membrane, circular substantially flat because the filtering surface is easily accessible for the deposit. This is, for example, a membrane "disram" manufactured by the company TAMI industries (France) with a diameter of about 90 mm, a thickness of between 1 and 5 mm, a porosity between 30 and 70% and with a pore size between 1 and 1000 nm.

A fixed layer of a photocatalyst such as TiO 2 is deposited on one of the faces (fi) of the membrane by any suitable technique (sol-gel, isostatic compression, CVD, hydrothermal synthesis, synthesis of supercritical CO2 from alkoxides). The membrane can then be sintered at high temperature, typically 250 to 600 ⁰ C or more.

The first and second compartments (compartments Ci and C2) of the device according to the present invention correspond respectively to the upper module (2) and to the lower module (3) of the casing, said modules being separated by the membrane (1) whose face (fi The device of FIG. 1 is advantageously used in tangential mode: the liquid to be treated circulates parallel to the surface of the membrane (1). In this case, the fluid containing the compound to be removed is introduced into the first compartment (compartment Ci) via a pipe (5) by means of any pumping member and, in general, by any system for moving a fluid and follows a spiral created by an inner member of spiral shape (6). It should be noted that the volume of this spiral is, in fact, the volume of the first compartment (compartment Ci). The fluid exits the device via a valve (7).

In this case, the recommended UV LED mounting (8) is a spiral arrangement on the spiral path of the fluid. These LEDs (8) are inserted in the upper flange of the module in holes allowing their attachment with a sealing system vis-à-vis the outside. The seal must withstand a fluid circulation pressure of the order of 0.1 to 10 bar, preferably 1 to 5 bar.

The second compartment (compartment C2) is supplied with a fluid containing oxygen such as air or oxygen via a valve (9), by means of a fluid injection system containing the oxygen. This power supply is performed for a duration di. The elapsed time, the fluid injection pump is stopped, the valve (9) is closed and disconnected from the source of fluid containing oxygen. The valve (9) is then connected to a device for recovering the cleaned permeate (i.e. the treated fluid having passed through the membrane) from the second compartment

(compartment C2) • This recovery is performed for a duration d2. The steps of supplying oxygen-containing fluid and recovering the permeate are repeated sequentially.

1.2. Device of Figure 2: For reasons of increase in production capacity, cylindrical membranes can also be used with layers internal or external active photocatalytic material.

Figure 2 is a schematic representation of such a cylindrical membrane (1). This membrane (1) is advantageously mineral, tubular or ductal. This is, for example, a single-channel membrane such as those manufactured by companies TAMI Industries, Orelis, Pall / SCT, etc. a length of between 250 and 1200 mm, a diameter of between 10 and 50 mm and a porosity between 30 and 70%.

A fixed layer of a photocatalyst (10) such as TiO 2 is deposited on the internal face (f ₂ ) of the membrane by any suitable technique (sol-gel, isostatic compression, CVD, hydrothermal synthesis, synthesis in CO2 supercritical from alkoxides). The membrane can then be sintered at high temperature, typically 250 to 600 ⁰ C or more. The first and second compartments

(C1 and C2 compartments) of the device according to the present invention respectively correspond to the inside of the tubular membrane (2) and outside the tubular membrane (3). The device of FIG. 2 is advantageously used in tangential mode. The liquid to be treated circulates parallel to the surface of the membrane (1): liquid vein flowing from the fluid inlet (A) to the fluid outlet (A). The internal UV LEDs (8) are installed inside the liquid vein in parallel in the form of a "garland" of to irradiate the photocatalytic material (10). The dimensions of the fluid stream are compatible with the focusing of the light beam emitted by the UV LEDs (8) to obtain efficient activation of the photocatalytic material.

As for the device of Figure 1, the membrane (1) of Figure 2 allows, sequentially, to introduce into the liquid vein oxygen and recover the permeate.

The form of implementation in which the device according to the present invention comprises a second compartment (compartment C2) and several first compartments (compartments Ci) corresponds to a device of the membrane housing type comprising several devices as defined in FIG. , the interior space of the housing except for those devices corresponding to the second compartment

(compartment C2) •

2. Device with several second compartments (compartments C2):

The UV LED system integrated into a membrane photocatalytic reactor can also be applied to systems with a large membrane surface typically greater than 1 m ² (and up to several hundred m ² ), which is then suitable for pilot or industrial scales.

The series and parallel combination of single-channel or multichannel commercial membranes, such as those manufactured by TAMI Industries, Orelis, Pall / SCT, etc. the outside or inside of which is covered with a photocatalytic material, makes it possible to envisage an increase in the membrane surface and to cover all the flow ranges to be treated, conventionally of 1 m ³ . h ^"1 up to several hundred or even thousands of m ³ h ^{" 1} .

It is proposed to use these membrane modules in housings modified to receive the appropriate sources of UV radiation (preferably LED) in internal or peripheral emission. Depending on the size of the industrial device, a combination of membranes and LED layout is possible.

Figures 3 and 4 show two examples of such devices prepared from TIS type devices manufactured by TAMI Industrie.

The devices of FIGS. 3 and 4 comprise, in their center, membranes (11) whose outer layer has photocatalytic properties and whose role is to diffuse oxygen. The membranes (12) located at the periphery of the device are membranes allowing the drainage of the fluid (B)

(permeate consisting of oxidized and / or hydrolyzed compounds). The membranes (11) and (12) are arranged parallel to each other, parallel to the longitudinal axis of the device.

UV LEDs (8) are connected in series and in parallel and located at the periphery of the device

(Figures 3 and 4). The device is made of a material transparent to UV radiation of the methacrylate type allowing the UV radiation emitted by the LEDs (8) to effectively activate the photocatalytic material. (10). The material of the device may also be opaque, pierced with holes in which the LEDs are inserted in a sealed manner to withstand a pressure of 0.1 to 30 bar and in particular of 1 to 10 bar. The second compartments (compartments C2) in the devices of FIGS. 3 and 4 correspond to the internal volume of the tubular membranes (11) and (12) while the first compartment (compartment Ci) corresponds to the internal volume of the device surrounding the tubular membranes (11). ) and (12).

Nevertheless, LED strings (13) can also be arranged inside the membrane holder device in order to irradiate all the active surfaces (FIG. 4). In the device of FIG. 4, a part of the filtering membranes (12) is conserved to drain the polluted permeate (liquid (B)) and to retain the TiO 2 particles (or any other photocatalyst), a part of the membranes (11) can to be used to diffuse oxygen, part of the membranes is replaced by a UV emission device (for example LEDs, but also UV lamps of geometry compatible with the size of the membranes they replace). The photocatalyst may be dispersed in powder form and / or deposited on the surface of the membranes so that the UV insolation illuminates all the active surfaces.

The catalyst material in dispersed form can be introduced into the fluid (A) during its introduction into the first compartment (compartment Ci) or prior to this introduction. Finally, the liquid circulation system (B) is coupled directly to the membrane casing without circulating through an external pumping loop.

REFERENCES

1. Schneider, C, "Water disinfection by UV radiation" Water, industry, nuisances, 1991. 149: p. 64-66.

2. Margolin, A. B., "Control of microrganisms in water and drinking water source" Manual of environmental microbiology. "1997: Washington, US, pp. 195-202." Patent Application EP 0317735 "Apparatus for disinfecting waste water" published May 31, 1989.

4. Patent Application DE3117473 "Disinfection apparatus for swimming pools and water service" published November 25, 1982. 5. Hermann, J.-M., "Photocatalysis: Fundamentals and Openness to Process Engineering." 2007, French Society of Process Engineering: Paris.

6. US 5118422 "Photocatalytic treatment of water" published June 2, 1992.

7. Cho, M., et al., "Linear correlation between inactivation of E. coli and radical OH in TiO2 photocatalytic disinfection." Water research, 2004 (38): p. 1069-1077. International application WO 03/014030

"Sterilization method of UV water / TiO2 photocatalytic reaction and reactor therefor" published on February 20, 2003.

9. International Application WO 2007/079749 "Method and System for photocatalytic removal of inorganic halogens by reduction "published on July 19, 2007.

10. International Application WO 2007/113537 "Fluid treatment apparatus comprising ultraviolet light emitting diode" published October 11, 2007.

11. US2007 / 009404 "Illuminated devices using UV-LEDs", published on January 11, 2007.

12. Patent Application US2006 / 163126 "UV led based water purification module for intermittantly operable flow-through hydration Systems" published July 27, 2006.

13. Patent Application US2003 / 203816 "Titania-coated honeycomb catalyst matrix for UV-photocatalytic oxidation of organic pollutants, and process for making" published October 30, 2003.

14. Azrague, K., et al., "A new combination of a membrane and a photocatalytic reactor for depollution of turbid water." Applied catalysis B environmental, 2007. 70 (3-4): p. 197-204.

15. Bellobono, I. R., F. Morazzoni, and P. M. Tozzi, "Photocatalytic membrane modules for drinking water purification in domestic and community appliances" Int. J. of Photoenergy, 2005. 07: p. 109-113. 16. Patent Application JP2002001332 "UV irradiation type membrane filtration apparatus" published on January 8, 2002.

Claims

1) Device for removing at least one compound contained in a fluid, comprising: - a UV radiation system, at least a first compartment containing a photocatalytic material capable of being insolated by said UV radiation system,

means adapted to bring said fluid into said at least one first compartment, characterized in that said device comprises:

at least one second compartment separate from said at least one first compartment, adapted to recover said fluid after removal of said compound, means adapted to bring an oxygen-containing fluid into at least a second compartment,

a membrane separating said first and second compartments and adapted to the passage of at least one fluid.

2) Device according to claim 1, characterized in that said membrane is selected from microfiltration membranes, ultrafiltration membranes, nanofiltration membranes and reverse osmosis membranes. 3) Device according to claim 1 or 2, characterized in that said membrane is substantially flat shape.

4) Device according to claim 1 or

2, characterized in that said membrane is cylindrical in shape.

5) Device according to any one of the preceding claims, characterized in that said UV radiation system comprises at least one light emitting diode (LED).

6) Device according to any one of the preceding claims, characterized in that said UV radiation system comprises at least two LEDs connected in series.

7) Device according to any one of claims 1 to 5, characterized in that said UV radiation system comprises at least two LEDs connected in parallel.

8) Device according to any one of the preceding claims, characterized in that said photocatalytic material consists of semiconductor particles.

9) Device according to any one of the preceding claims, characterized in that said Photocatalytic material is in the form of a deposit.

10) Device according to any one of the preceding claims, characterized in that said photocatalytic material is in dispersed form.

11) Device according to any one of claims 1 to 10, characterized in that said device comprises a single second compartment.

12) Device according to claim 11, characterized in that said device comprises at least two first compartments.

13) Device according to any one of claims 1 to 10, characterized in that said device comprises at least two second compartments.

14) Use of a device according to any one of the preceding claims for removing at least one compound contained in a fluid.

15) Use according to claim 14, characterized in that said compound is a pathogenic compound. 16) A method for removing a compound contained in a fluid (A) comprising the steps of: a) introducing said fluid (A) into a first compartment of a device as defined in any one of claims 1 to 13; b) introducing oxygen into said first compartment from at least a second compartment separated from said first compartment by a membrane as defined in any one of claims 2 to 4; c) irradiating a photocatalytic material as defined in any one of claims 5 to 7 and present in said first compartment with a UV radiation system as defined in any one of claims 8 to 10; d) recovering a fluid (B) no longer comprising said compound in at least one second compartment.

17) Method according to claim 16, characterized in that the second compartment of said step (b) is the same as that of said step (d) and said steps (b) and (d) are performed sequentially.