Method for the extraction and use of oxygen from an aqueous medium

Abstract

The present invention relates to a method for the extraction of oxygen from an aqueous medium, the method comprising the following steps: - providing an oxygen-permeable extraction membrane (18); then - bringing a first aqueous medium (14) containing oxygen (12) into contact with a first face (20) of the membrane; - bringing a second aqueous medium (16) comprising a carrier compound (30) into contact with a second face (22) of the membrane; - diffusing the oxygen from the first aqueous medium into the second aqueous medium through the membrane (18); and forming a complex compound (32) by binding the oxygen (12) to the carrier compound (30). The carrier compound (30) is an organic molecule selected from among an annelid globin, an annelid globin protomer, and an annelid extracellular hemoglobin.

Description

[0001] DESCRIPTION

[0002] TITLE: Process for the extraction and use of oxygen from an aqueous medium

[0003] The present invention relates to a method for extracting oxygen (O2) from an aqueous medium, of the type comprising the following steps: providing an extraction membrane, permeable to oxygen, said extraction membrane comprising a first and a second opposite face; then bringing into contact, with the first face of the extraction membrane, a first aqueous medium containing oxygen; bringing into contact, with the second face of the extraction membrane, a second aqueous medium; said second aqueous medium comprising a support compound, capable of binding to oxygen to form a complex compound; diffusion of oxygen from the first aqueous medium to the second aqueous medium through the extraction membrane; and formation of the complex compound by binding of the oxygen with the support compound.

[0004] A similar method is known in particular from document EP0176446 and aims to use the extracted oxygen in the operation of a fuel cell. Such a method notably involves an oxygen support compound comprising organic groups.

[0005] The aim of the present invention is to propose an improved method, making it possible to achieve an extraction efficiency which is significantly higher than known methods.

[0006] To this end, the invention relates to an extraction process of the aforementioned type, in which the support compound is an organic molecule chosen from an Annelid globin, an Annelid globin protomer and an Annelid extracellular hemoglobin.

[0007] According to other advantageous aspects of the invention, the extraction method comprises one or more of the following characteristics, taken individually or in all technically possible combinations:

[0008] - the carrier compound is an organic molecule selected from the extracellular hemoglobins of the Lumbricidae family, the extracellular hemoglobins of the Arenicolidae family and the extracellular hemoglobins of the Nereididae family, preferably from the extracellular hemoglobin of Lumbricus terrestris, the extracellular hemoglobin of Arenicola sp and the extracellular hemoglobin of Nereis sp, more preferably from the extracellular hemoglobin of Arenicola marina and Nereis virens, more preferably the extracellular hemoglobin of Arenicola marina; - a concentration of carrier compound in the second aqueous medium is greater than 1 g / L;

[0009] - the first aqueous medium is sea water.

[0010] The invention further relates to an electrochemical process comprising a step of electrochemical reduction of the complex compound resulting from an extraction process as described above.

[0011] According to other advantageous aspects of the invention, the electrochemical process comprises one or more of the following characteristics, taken individually or in all technically possible combinations:

[0012] - the electrochemical reduction of the complex compound is carried out in a third aqueous medium;

[0013] - the third aqueous medium comprises a redox mediator, preferably 2,2'-azino-bis-(3-ethylbenzothiazoline-6-sulfonic acid) (ABTS);

[0014] - the electrochemical reduction of the complex compound comprises a reduction of the oxygen of said complex compound, so as to dissociate said oxygen from the support compound;

[0015] - the reduction of oxygen from the complex compound is carried out at the cathode of a fuel cell.

[0016] The invention further relates to a fuel cell comprising: an anode; a cathode; and a circulation conduit for a flow of a fluid capable of providing oxygen, the cathode being arranged in said circulation conduit; the fuel cell being configured for the implementation of an electrochemical method as described above, the cathode being capable of reducing the oxygen of the complex compound.

[0017] According to an advantageous aspect of the invention, the fuel cell comprises an arrangement for circulating a flow of third aqueous medium, comprising the complex compound, in the circulation conduit.

[0018] The invention will be better understood on reading the description which follows, given solely as a non-limiting example and made with reference to the drawings in which:

[0019] [Fig 1] Figure 1 is a schematic view of a first device, for implementing an extraction method according to an embodiment of the invention; and

[0020] [Fig 2] Figure 2 is a schematic view of a second device, for implementing a method of using extracted oxygen, according to one embodiment of the invention.

[0021] Figure 1 shows a first device 10 for extracting oxygen (O2). More specifically, the first device 10 is configured for extracting oxygen 12 from a first aqueous medium 14 to a second aqueous medium 16. The first device 10 comprises an extraction membrane 18, permeable to oxygen and hydrophobic. Said extraction membrane 18 comprises a first 20 and a second 22 opposite faces.

[0022] The extraction membrane 18 comprises, for example, micro-channels 24 open on each of the first 20 and second 22 faces.

[0023] The extraction membrane 18 defines a first 26 and a second 27 spaces, delimited respectively by the first 20 and by the second 22 faces.

[0024] According to a first embodiment, the extraction membrane 18 and the first 20 and second 22 faces are arranged in a substantially flat manner.

[0025] According to a second embodiment, the extraction membrane 18 is closed on itself in a substantially cylindrical manner, around an axis parallel to a main direction 28. The first 26 and second 27 spaces are then in the form of an internal space and an external space, substantially coaxial.

[0026] The internal space is located on the side of the first 20 and second 22 faces arranged concavely. The external space is located on the side of the first 20 and second 22 faces arranged convexly. According to a first embodiment variant, the first space 26 is the internal space. According to a second embodiment variant, the second space 27 is the internal space.

[0027] The X40 liquid-cel membrane, marketed by the company 3M, is particularly suitable for the implementation of the 18 extraction membrane.

[0028] The first aqueous medium 14, to be extracted, is rich in oxygen 12. Preferably, the first aqueous medium 14 is a saline solution. More preferably, the first aqueous medium 14 comprises seawater, pure, diluted or in the form of a mixture.

[0029] The second aqueous medium 16 comprises a support compound 30, capable of binding to oxygen 12 to form a complex compound 32.

[0030] According to one embodiment, each molecule of support compound 30 comprises several binding sites with an oxygen molecule 12; the corresponding complex compound 32 therefore comprises several oxygen molecules 12 bound to a molecule of support compound 30.

[0031] According to one embodiment, the support compound 30 comprises a number of binding sites with an oxygen molecule 12 of between 1 and 200.

[0032] According to the invention, the support compound 30 is an organic molecule chosen from an annelid globin, an annelid globin protomer and an annelid extracellular hemoglobin. Such organic molecules are for example described in document EP2956161 in the name of the Applicant. Preferably, the support compound 30 is chosen from the extracellular hemoglobins of the Lumbricidae family, the extracellular hemoglobins of the Arenicolidae family and the extracellular hemoglobins of the Nereididae family. More preferably, the support compound 30 is chosen from the extracellular hemoglobin of Lumbricus terrestris, the extracellular hemoglobin of Arenicola sp and the extracellular hemoglobin of Nereis sp. Even more preferably, the support compound 30 is chosen from the extracellular hemoglobin of Arenicola marina and Nereis virens.

[0033] Even more preferably, the support compound 30 is the extracellular hemoglobin of Arenicola marina. Said extracellular hemoglobin has 156 binding sites with an oxygen molecule 12.

[0034] Preferably, a concentration of carrier compound 30 in the second aqueous medium 16 is greater than 1 g / L.

[0035] An oxygen extraction method, implementing the first device 10, will now be described.

[0036] The first 14 and second 16 aqueous media are arranged respectively in the first 26 and in the second 27 spaces. More precisely, the first 14 and second 16 aqueous media are simultaneously brought into contact with the extraction membrane 18, respectively with the first 20 and with the second 22 faces.

[0037] According to one embodiment, the first aqueous medium 14 is circulated in the first space 26 in the form of a first flow 36 and / or the second aqueous medium 16 is circulated in the second space 27 in the form of a second flow 37.

[0038] Each of the first 36 and second 37 flows is parallel to the main direction 28. Preferably, the first 36 and second 37 flows are countercurrent.

[0039] The oxygen 12 from the first aqueous medium 14 diffuses into the second aqueous medium 16 through the extraction membrane 18. As it is dissolved in the second aqueous medium 16, the oxygen 12 binds with the support compound 30 to form the corresponding complex compound 32.

[0040] An oxygen 12 concentration gradient is therefore established between the first 20 and second 22 faces of the extraction membrane 18, facilitating the diffusion of oxygen 12 from the first 14 to the second 16 aqueous medium.

[0041] Thus, the oxygen 12 extracted from the first aqueous medium 14 is found in the second aqueous medium 16, in the form of a complex compound 32 with the support compound 30. As indicated previously, a complex compound 32 preferably comprises several oxygen molecules linked to the same molecule of support compound 30. Figure 2 shows a second device 40, for the use of the oxygen extracted by means of the first device 10 previously described.

[0042] In the illustrated embodiment, the second device 40 is a fuel cell. More specifically, the second device 40 is a proton exchange membrane fuel cell.

[0043] In particular, the second device 40 comprises: an anode 42; a cathode 44; a proton exchange membrane 46; and a first fluid circulation arrangement 48. The second device 40 further comprises means (not shown) for circulating a flow of electrons between the anode 42 and the cathode 44.

[0044] In the embodiment shown, the second device 40 further comprises a second fluid circulation arrangement 50.

[0045] The cathode 44 is capable of implementing an electrochemical reduction of the complex compound 32 previously described, resulting from a bond between one or more oxygen molecules 12 and a molecule of support compound 30.

[0046] More precisely, the cathode 44 is capable of implementing an electrochemical reduction of the oxygen 12 of the complex compound 32, so as to dissociate said oxygen from the support compound 30.

[0047] Preferably, the cathode 44 comprises adsorption sites for the complex compound 32, allowing said complex compound to undergo electrochemical reduction. For example, the cathode 44 comprises a network of fibers 52 formed from an electrically conductive material, such as carbon fibers.

[0048] The proton exchange membrane 46 is arranged between the anode 42 and the cathode 44, said membrane being capable of implementing a flow 54 of protons between the anode 42 and the cathode 44. The proton exchange membrane 46 is for example a perfluorosulfonic acid membrane of the Nation™ type.

[0049] The first fluid circulation arrangement 48 comprises a circulation conduit 56, the cathode 44 being arranged in said conduit 56. The circulation conduit 56 comprises an inlet 58 and an outlet 60.

[0050] The first arrangement 48 further comprises a fluid inlet 62, connected to the inlet 58 of the circulation conduit 56. In the embodiment shown, the fluid inlet 62 comprises an additive supply 64, as described below.

[0051] The second circulation arrangement 50 is capable of supplying the anode 42 with a fuel flow 66, capable of providing protons, in particular dihydrogen, as described below.

[0052] An electrochemical process, implementing the second device 40, will now be described. The second circulation arrangement 50 supplies the anode 42 with the fuel flow 66 comprising dihydrogen. Said dihydrogen decomposes into protons and electrons at the anode 42. The electrons move towards the cathode 44 in the form of an electric current. The protons pass through the exchange membrane 46, in the form of the proton flow 54.

[0053] Furthermore, a flow of an aqueous medium, comprising the complex compound 32 previously described, is directed towards the fluid inlet 62. In the embodiment shown in FIG. 2, the second flow 37 of second aqueous medium 16, previously described, is directed towards the fluid inlet 62 downstream of the first device 10.

[0054] In the embodiment shown, at the inlet 62, an additive is added to the aqueous medium comprising the complex compound 32, via the feed 64. A third aqueous medium 68 is thus formed upstream of the inlet 58.

[0055] Preferably, the additive comprises at least one redox mediator. More preferably, the additive contains 2,2'-azino-bis-(3-ethylbenzothiazoline-6-sulfonic acid) (ABTS).

[0056] According to one embodiment, the redox mediator is introduced into the second aqueous medium 16 from the oxygen extraction step.

[0057] The third aqueous medium 68 passes through the circulation conduit 56, from the inlet 58 to the outlet 60. The molecules of complex compound 32 make electrical contact with the network of fibers 52 of the cathode 44.

[0058] The oxygen molecules of said complex compound 32 then react with the electrons and protons arriving at the cathode 44, to form water molecules. This reaction is accompanied by the release of said oxygen molecules by the support compound 30 forming the complex compound.

[0059] The reduction of oxygen in the complex compound 32 is notably promoted by the presence of redox mediator in the third aqueous medium 68.

[0060] Molecules of support compound 30, entirely or partially devoid of oxygen, are thus recovered at the outlet 60 of the circulation conduit 56.

[0061] Preferably, said support compound 30 recovered at the outlet of the second device 40 is recycled for the implementation of the first device 10, previously described.

[0062] The oxygen enabling the operation of the fuel cell, formed by the second device 40, is thus provided by the extraction of the first aqueous medium 14 using the first device 10, as described previously.

[0063] Consequently, the combination of the first 10 and second 40 devices previously described makes it possible to power a fuel cell using oxygen extracted from an aqueous medium such as seawater. The use of the support compound 30 makes it possible to concentrate the dissolved oxygen by a factor of 1000 and to convert this into energy in the fuel cell with a COP greater than 3 (Energy restored / Energy necessary for the extraction of oxygen from the first aqueous medium).

Claims

CLAIMS 1. Method for extracting oxygen from an aqueous medium, comprising the following steps: - providing an extraction membrane (18), permeable to oxygen, said extraction membrane comprising a first (20) and a second (22) opposite faces; then - bringing into contact, with the first face (20) of the extraction membrane, a first aqueous medium (14) containing oxygen (12); - bringing into contact, with the second face (22) of the extraction membrane, a second aqueous medium (16); said second aqueous medium comprising a support compound (30), capable of binding to oxygen to form a complex compound (32); - diffusion of oxygen from the first aqueous medium to the second aqueous medium through the extraction membrane (18); and formation of the complex compound (32) by binding of the oxygen (12) with the support compound (30); the method being characterized in that the support compound (30) is an organic molecule chosen from an Annelid globin, an Annelid globin protomer and an Annelid extracellular hemoglobin.

2. Extraction method according to claim 1, wherein the support compound (30) is an organic molecule chosen from the extracellular hemoglobins of the Lumbricidae family, the extracellular hemoglobins of the Arenicolidae family and the extracellular hemoglobins of the Nereididae family, preferentially from the extracellular hemoglobin of Lumbricus terrestris, the extracellular hemoglobin of Arenicola sp and the extracellular hemoglobin of Nereis sp, more preferentially from the extracellular hemoglobin of Arenicola marina and Nereis virens, more preferentially the extracellular hemoglobin of Arenicola marina.

3. Extraction method according to claim 1 or 2, wherein a concentration of carrier compound (30) in the second aqueous medium (16) is greater than 1 g / L.

4. Extraction method according to one of the preceding claims, in which the first aqueous medium (14) is sea water.

5. Electrochemical process, comprising a step of electrochemical reduction of the complex compound (32) resulting from an extraction process according to one of the preceding claims.

6. Electrochemical method according to claim 5, wherein the electrochemical reduction of the complex compound (32) is carried out in a third aqueous medium (68).

7. Electrochemical method according to claim 6, wherein the third aqueous medium (68) comprises a redox mediator, preferably 2,2'-azino-bis-(3-ethylbenzothiazoline-6-sulfonic acid) (ABTS).

8. Electrochemical method according to one of claims 5 to 7, in which the electrochemical reduction of the complex compound (32) comprises a reduction of the oxygen (12) of said complex compound, so as to dissociate said oxygen from the support compound (30).

9. Electrochemical method according to claim 8, wherein the reduction of oxygen (12) of the complex compound (32) is carried out at the cathode (44) of a fuel cell (40).

10. Fuel cell (40) comprising: an anode (42); a cathode (44); and a conduit (56) for circulating a flow of a fluid capable of providing oxygen, the cathode (44) being arranged in said circulation conduit; the fuel cell being configured for implementing an electrochemical method according to claim 9, the cathode being capable of reducing the oxygen (12) of the complex compound (32).

11. Fuel cell according to claim 10 taken in combination with one of claims 6 or 7, the fuel cell comprising an arrangement (48) for the circulation of a flow of third aqueous medium (68), comprising the complex compound (32), in the circulation conduit (56).

Images