Spatially oriented channel anodes, bioelectrochemical systems, and their application to wastewater resource recovery

Abstract

The application provides a spatially oriented channel anode and a preparation method thereof, a bioelectrochemical system and application. The spatially oriented channel anode comprises a carbon skeleton, and the carbon skeleton has a pore channel which extends in a single direction. The specific surface area of the anode is improved, and when the anode is applied to a bioelectrochemical system, the growth area of microorganisms on the surface of the anode can be effectively improved. The carbon skeleton anode has the effect of efficient current collection, which helps to improve the electrochemical activity thereof. After the bioelectrochemical system is started, the oriented channel loaded with microorganisms can constitute a micro-channel reactor, which can strengthen the degradation effect of pollutants when sewage flows through, and improve the chemical energy conversion and in-situ self-driven resource recovery efficiency of the sewage. Meanwhile, the bioelectrochemical system can be used as a desalination system, a concentration system and a desalination-concentration composite system, so as to realize the effects of removing ionic substances in sewage, recovering nitrogen and phosphorus resources and synchronously and comprehensively purifying.

Description

TECHNICAL FIELD

[0001] The present application relates to the field of bio-electrochemistry, in particular, to a spatially oriented channel anode, a bio-electrochemical system and its application in sewage resourceization, more particularly, to a spatially oriented channel anode and a preparation method thereof, a bio-electrochemical system and its application in sewage purification and resource recovery. BACKGROUND

[0002] In response to the national "double carbon" call, developing clean and low-carbon sewage treatment technology has become one of the important research directions in the environmental field. Bio-electrochemical system can utilize special electroactive microorganisms on the anode to realize sewage purification and energy and resource recovery, and is a promising sewage resourceization and energy technology. Bio-electrochemical system can convert chemical energy in sewage into electrical energy, and efficient anode is an important prerequisite for realizing sewage purification and energy conversion of bio-electrochemical system. A good anode should provide a more suitable hosting space for microorganisms, while having efficient electron conduction capacity and effective space mass transfer process. Therefore, designing the spatial structure of the anode and accelerating the electron transfer process of the anode are of great significance for strengthening the performance of the anode and improving the sewage energy production process of the bio-electrochemical system. SUMMARY

[0003] The present application aims to at least partially solve one of the technical problems in the related art. To this end, one object of the present application is to provide a spatially oriented channel anode having the advantage of efficient current collection.

[0004] In one aspect of the present application, a spatially oriented channel anode is provided. According to embodiments of the present application, the spatially oriented channel anode includes a carbon skeleton having a pore channel, the pore channel being unidirectionally extended. Thus, the formation of the pore channel effectively improves the spatial structure inside the anode and increases the specific surface area of the anode. When applied in a bio-electrochemical system, it can effectively increase the growth area of microorganisms on the surface of the anode. The carbon skeleton anode has the effect of efficient current collection. The unidirectional extension of the pore channel is conducive to the directional transmission of electrons and protons generated by microorganisms on the spatially oriented channel anode, thereby helping to improve its electrochemical activity. Moreover, after starting the bio-electrochemical system, the directional channel loaded with microorganisms can constitute a micro-channel reactor, which can strengthen the degradation effect of pollutants when sewage flows through, and can improve the chemical energy conversion and in-situ self-driven resource recovery efficiency of the sewage.

[0005] According to embodiments of the present application, the spatially oriented channel anode further includes a doped metal attached to the surface of the carbon skeleton, and optionally, the doped metal includes a transition metal.

[0006] In another aspect of the present application, the present application provides a method for preparing the spatially oriented channel anode. According to an embodiment of the present application, the method for preparing the spatially oriented channel anode comprises: mixing a polymer powder with a first solvent and adjusting to be acidic to obtain a cross-linked polymer solution; subjecting the cross-linked polymer solution to freeze-drying in a mold with a metal base to obtain an aerogel with spatially oriented channels; and subjecting the aerogel to pyrolysis treatment to obtain the spatially oriented channel anode. Thus, the above preparation method can effectively form unidirectional extending pore channels in the carbonized carbon skeleton, thereby effectively improving the spatial structure of the anode and increasing the specific surface area of the anode. When applied in a bio-electrochemical system, the carbon skeleton anode can effectively increase the growth area of microorganisms on the anode surface, has the effect of efficient current collection, is conducive to the directional transmission of electrons and protons generated by microorganisms on the spatially oriented channel anode, and thus helps to improve the electrochemical activity. Moreover, after starting the bio-electrochemical system, the oriented channels loaded with microorganisms can constitute a micro-channel reactor, which can strengthen the degradation effect of pollutants when sewage flows through, and can improve the chemical energy conversion and in-situ self-driven resource recovery efficiency of the sewage.

[0007] According to an embodiment of the present application, at least one of the following conditions is met: the mass concentration of the polymer in the cross-linked polymer solution is 0.25% to 5%; the polymer comprises at least one of chitosan, sodium alginate, and polyvinyl alcohol; the temperature of the pyrolysis treatment is 600°C to 1200°C, and the holding time is 1 to 4 hours; and the heating rate of the pyrolysis treatment is 2 to 10°C / min.

[0008] According to an embodiment of the present application, the preparation method further comprises: adding a metal salt and / or a metal-based ZIF precursor to the cross-linked polymer solution.

[0009] According to an embodiment of the present application, the mass concentration of the metal salt in the cross-linked polymer solution is 0.1% to 5% based on the total mass of the polymer; and / or, the mass concentration of the metal-based ZIF precursor in the cross-linked polymer solution is 0.1% to 2% based on the total mass of the polymer, and / or, the preparation method of the metal-based ZIF precursor comprises: dissolving zinc nitrate and a metal salt in a second solvent to obtain a first mixed solution; dissolving 2-methylimidazole in a third solvent to obtain a second mixed solution; mixing and stirring the first mixed solution and the second mixed solution, and centrifuging to obtain the metal-based ZIF precursor.

[0010] In yet another aspect of the present application, the present application provides a bio-electrochemical system. According to an embodiment of the present application, the bio-electrochemical system comprises: an anode unit comprising at least one of the aforementioned spatially oriented channel anode, and the surface of the spatially oriented channel anode is attached with electroactive microorganisms; an electrolyte; and a cathode unit arranged in a cylindrical shape around the outside of the anode unit. In this way, the anode of the bio-electrochemical system has a large area of microorganism attachment, and the carbon skeleton anode has a high current collection effect. After the bio-electrochemical system is started, the oriented channel loaded with microorganisms can form a micro-channel reactor, which can strengthen the degradation effect of pollutants when the wastewater flows through, and improve the chemical energy conversion and in-situ self-driven resource recovery efficiency of the wastewater.

[0011] According to an embodiment of the present application, the bio-electrochemical system further comprises: an ion exchange membrane comprising at least one anion exchange membrane and at least one cation exchange membrane, and the ion exchange membrane is arranged in a cylindrical shape between the anode unit and the cathode unit.

[0012] According to an embodiment of the present application, the anode unit comprises a plurality of the spatially oriented channel anodes, and the anode unit satisfies one of the following conditions: the plurality of the spatially oriented channel anodes are arranged in series through a conductive wire; the plurality of the spatially oriented channel anodes are arranged in parallel through the conductive wire; the anode unit comprises a plurality of parallel anode combinations, each of the anode combinations comprises a plurality of the spatially oriented channel anodes arranged in series; and the spatially oriented channel anode is in a cylindrical shape.

[0013] According to an embodiment of the present application, the cathode unit and / or the ion exchange membrane is in a cylindrical shape.

[0014] In yet another aspect of the present application, the present application provides a desalination system. According to an embodiment of the present application, the desalination system comprises the aforementioned bio-electrochemical system, wherein the ion exchange membrane comprises an anion exchange membrane and a cation exchange membrane, the anion exchange membrane is arranged in a cylindrical shape around the spatially oriented channel anode, and is arranged close to the spatially oriented channel anode, and the cation exchange membrane is arranged in a cylindrical shape on one side of the cathode unit. In this way, the desalination system can effectively purify the wastewater.

[0015] In yet another aspect of the present application, the present application provides a concentration system. According to an embodiment of the present application, the concentration system comprises the bio-electrochemical system as described above, wherein the ion exchange membrane comprises a layer of anion exchange membrane and a layer of cation exchange membrane, the cation exchange membrane is cylindrically arranged around the space-oriented channel anode and is close to the space-oriented channel anode, and the anion exchange membrane is cylindrically arranged around one side of the cathode unit. Thus, the concentration system can effectively realize the recovery of resources (such as nitrogen and phosphorus).

[0016] In yet another aspect of the present application, the present application provides a desalination-concentration combined system. According to an embodiment of the present application, the desalination-concentration combined system comprises the bio-electrochemical system as described above, wherein the ion exchange membrane comprises multiple layers of anion exchange membrane and multiple layers of cation exchange membrane, and the multiple layers of anion exchange membrane and the multiple layers of cation exchange membrane are cylindrically arranged and sequentially overlapped between the space-oriented channel anode and the cathode unit. Thus, the system can simultaneously realize the purification of wastewater and the recovery of resources, and improve the treatment efficiency of wastewater pollutants.

[0017] In yet another aspect of the present application, the present application provides the application of the desalination system, the concentration system or the desalination-concentration system as described above in wastewater purification and resource recovery. BRIEF DESCRIPTION OF DRAWINGS

[0018] The above and / or additional aspects and advantages of the present application will become apparent and be readily understood from the following description, taken in conjunction with the following drawings, in which:

[0019] Figure 1 is a structural schematic diagram of a bio-electrochemical system in an embodiment of the present application;

[0020] Figure 2 is a structural schematic diagram of a bio-electrochemical system in another embodiment of the present application;

[0021] Figure 3 is a structural schematic diagram of a bio-electrochemical system in another embodiment of the present application;

[0022] Figure 4 is a cross-sectional schematic diagram of a bio-electrochemical system in another embodiment of the present application;

[0023] Figure 5 is a cross-sectional schematic diagram of a bio-electrochemical system in another embodiment of the present application;

[0024] Figure 6 is a cross-sectional schematic diagram of a bio-electrochemical system in another embodiment of the present application;

[0025] Figure 7is a structural schematic diagram of an anode unit in another embodiment of the present application;

[0026] Figure 8 is a structural schematic diagram of an anode unit in another embodiment of the present application;

[0027] Figure 9 is a structural schematic diagram of an anode unit in another embodiment of the present application;

[0028] Figure 10 is a schematic diagram of the operation principle of a bioelectrochemical system in another embodiment of the present application;

[0029] Figure 11 is a schematic diagram of the operation principle of a bioelectrochemical system in another embodiment of the present application;

[0030] Figure 12 is a schematic diagram of the operation principle of a bioelectrochemical system in another embodiment of the present application;

[0031] Figure 13 and Figure 14 are scanning electron microscope images of the spatially oriented channel anodes in Examples 1 to 6;

[0032] Figure 15 are conductivity test images of the spatially oriented channel anodes in Examples 1 to 6;

[0033] Figure 16 are electrochemical activity test images of the spatially oriented channel anodes in Examples 1 to 6 and the anodes in Comparative Examples 1 and 2;

[0034] Figure 17 are bioelectrochemical CV curve images of the spatially oriented channel anodes in Examples 1 to 6 and the anodes in Comparative Examples 1 and 2;

[0035] Figure 18 are power generation performance test images of the bioelectrochemical systems corresponding to the spatially oriented channel anodes in Examples 1 to 6 and the anodes in Comparative Examples 1 and 2;

[0036] Figure 19 are pollutant removal performance and substrate utilization efficiency test images of the bioelectrochemical systems corresponding to the spatially oriented channel anodes in Examples 1 to 6 and the anodes in Comparative Examples 1 and 2;

[0037] Figure 20 are current density versus organic matter concentration test images of the bioelectrochemical systems corresponding to the spatially oriented channel anodes in Examples 1 to 6 and the anodes in Comparative Examples 1 and 2;

[0038] Figure 21 are stability test images of the bioelectrochemical systems corresponding to the spatially oriented channel anodes in Examples 5 and 6;

[0039] Figure 22 Figure 6 is a plot of the power generation performance of a bioelectrochemical system corresponding to the space-oriented channel anode of Example 6 and 7. DETAILED DESCRIPTION

[0040] The application will be described with reference to the embodiments. It will be understood that the embodiments are illustrative of the application and are not limiting of the scope of the application. Where specific technical or conditions are not indicated, the techniques or conditions described in the literature are used or the product manual is followed. Where the manufacturer of the reagent or instrument is not indicated, it should be assumed to be a conventional product available from commercial vendors.

[0041] The application will be described with reference to the embodiments. It will be understood that the embodiments are illustrative of the application and are not limiting of the scope of the application. Where specific technical or conditions are not indicated, the techniques or conditions described in the literature are used or the product manual is followed. Where the manufacturer of the reagent or instrument is not indicated, it should be assumed to be a conventional product available from commercial vendors.

[0042] In one aspect of the application, the application provides a space-oriented channel anode. According to embodiments of the application, the space-oriented channel anode comprises a carbon skeleton, the carbon skeleton having a pore channel, the pore channel extending in a single direction. Thus, the formation of the pore channel effectively improves the spatial structure inside the anode, increasing the specific surface area of the anode, which, when applied to a bioelectrochemical system, can effectively increase the growth area of microorganisms on the surface of the anode. The carbon skeleton anode has the effect of efficient current collection, and the single-directional extension of the pore channel is conducive to the directional transport of electrons and protons produced by microorganisms on the space-oriented channel anode, thereby helping to improve its electrochemical activity. Moreover, after starting the bioelectrochemical system, the directional channel loaded with microorganisms can constitute a micro-channel reactor, strengthening the degradation effect of pollutants when sewage flows through, and improving the chemical energy conversion and in-situ self-driven resource recovery efficiency of the sewage.

[0043] It should be noted that the "pore channel extending in a single direction" means that the pore channel is a directional channel extending in a single direction, i.e., the length of the pore channel extends in a single direction.

[0044] In some embodiments of the present application, the width of the pore channel in the spatially oriented channel anode is 1-100 microns, such as 1 micron, 5 microns, 10 microns, 20 microns, 30 microns, 40 microns, 50 microns, 60 microns, 70 microns, 80 microns, 90 microns, 100 microns, etc. In this way, the spatially oriented channel anode has good spatial channels while still maintaining good mechanical strength, ensuring its structural stability. In some specific embodiments, the width of the pore channel in the spatially oriented channel anode is 25-600 microns; in other specific embodiments, the width of the pore channel in the spatially oriented channel anode is 25-35 microns. The "width" mentioned above refers to the dimension in the direction perpendicular to the direction of extension of the channel in the spatially oriented channel anode.

[0045] According to some embodiments of the present application, the spatially oriented channel anode further comprises a doped metal, which is attached to the surface of the carbon skeleton, i.e. to the outer surface of the carbon skeleton and to the inner surface of the internal pore channel. In this way, metal active sites are introduced into the carbon skeleton, which can further enhance the efficiency of electron transfer between microorganisms and the electrode, improve the performance of the anode, and when applied to a bioelectrochemical system, can further improve the efficiency of chemical energy conversion and in-situ self-driven resource recovery of wastewater.

[0046] According to some embodiments of the present application, the doped metal comprises a transition metal. In this way, the transition metal has high reactivity, which can better improve the reactivity of the anode, and is low in cost and stable in properties. In some specific embodiments, the doped metal comprises at least one of iron, manganese, and cobalt, but is not limited thereto.

[0047] In some embodiments of the present application, the form of the doped metal attached to the surface of the carbon skeleton is not particularly limited, as long as it can effectively achieve strong attachment of the doped metal to the surface of the carbon skeleton and improve the activity of the anode. In some embodiments, the doped metal can be in the form of monodisperse atoms attached to the surface of the carbon skeleton; in other embodiments, the doped metal is in the form of metal oxides or metal nanoparticles attached to the surface of the carbon skeleton.

[0048] In another aspect of the present application, the present application provides a method for preparing the spatially oriented channel anode described above. According to embodiments of the present application, the method for preparing the spatially oriented channel anode comprises:

[0049] S100: mixing a polymer powder with a first solvent and adjusting it to be acidic to obtain a cross-linked polymer solution.

[0050] In some embodiments of the present application, the polymer comprises at least one of chitosan, sodium alginate, and polyvinyl alcohol. The above-mentioned polymers are easy to carbonize, low in cost, and widely available. In some embodiments, the first solvent can be water.

[0051] In some embodiments of the present application, the mixture of the polymer powder and the first solvent is adjusted to be weakly acidic, such as pH to 5-7, which facilitates the cross-linking of the polymer and the formation of the carbon skeleton.

[0052] According to embodiments of the present application, the mass concentration of the polymer in the cross-linked polymer solution is 0.25%-5%, such as 0.25%, 0.3%, 0.5%, 1.0%, 1.5%, 2%, 2.5%, 3%, 3.5%, 4%, 4.5%, 5%, etc. In this way, a carbon skeleton with good mechanical strength can be obtained, and the colonization of microorganisms and the formation of micro-channels (or pore channels) inside the carbon skeleton are facilitated. If the concentration of the polymer is relatively low, the internal skeleton of the carbon skeleton anode obtained is too loose, resulting in relatively poor mechanical strength; if the concentration of the polymer is relatively high, the carbon skeleton structure is relatively too dense, which is not conducive to the colonization of microorganisms and the formation of internal micro-channels. In some more specific embodiments, the mass concentration of the metal salt in the cross-linked polymer solution is 2%-5% based on the total mass of the polymer. In some specific embodiments, the polymer can be chitosan, and the mass concentration of the polymer in the cross-linked polymer solution is 0.5%-4%.

[0053] According to some embodiments of the present application, a metal-doped space-oriented channel anode can be further prepared, and the specific preparation method can include the following two cases:

[0054] In some embodiments, a metal salt is added to the cross-linked polymer solution. In this way, a space-oriented channel anode with a metal-doped surface can be prepared, and metal active sites are introduced into the carbon skeleton, which can further strengthen the electron transfer efficiency between microorganisms and the electrode, improve the performance of the anode, and further improve the chemical energy conversion and in-situ self-driven resource recovery efficiency of wastewater in a bio-electrochemical system.

[0055] In some specific embodiments, the metal salt is a transition metal salt, which can include at least one of a metal nitrate and a metal acetate. Further, in some specific embodiments, the mass concentration of the metal salt in the cross-linked polymer solution is 0.1%-5% based on the total mass of the polymer, such as 0.1%, 0.5%, 1.0%, 1.5%, 2.0%, 2.5%, 3.0%, 3.5%, 4.0%, 4.5%, 5.0%, etc., which is conducive to the attachment of the metal-doped on the surface of the carbon skeleton. If the concentration of the metal salt is relatively low, the loading amount of the metal-doped on the surface of the carbon skeleton is relatively small, which is relatively weak in strengthening the electron transfer efficiency between microorganisms and the electrode; if the concentration of the metal salt is relatively high, it will cause waste of raw materials.

[0056] In other embodiments, a metal-based ZIF precursor is added to the crosslinked polymer solution. This allows for the preparation of a spatially oriented channel anode with a metal-doped surface attached to the carbon framework. Introducing metal active sites into the carbon framework further enhances the electron transfer efficiency between microorganisms and the electrode, improving anode performance. When applied to bioelectrochemical systems, this can further enhance the chemical energy conversion and in-situ self-driven resource recovery efficiency of wastewater.

[0057] In some specific embodiments, the metal is a transition metal, such as iron, manganese, or cobalt, and the organic ligand used in the metal-based ZIF precursor is 2-methylimidazole. Further, in some specific embodiments, based on the total mass of the polymer, the mass concentration of the metal-based ZIF precursor in the crosslinked polymer solution is 0.1% to 2%, for example, 0.1%, 0.3%, 0.5%, 0.7%, 0.9%, 1.0%, 1.2%, 1.5%, 1.8%, 2.0%, etc. This is beneficial for the adhesion of the doped metal to the carbon framework surface. If the concentration of the metal-based ZIF precursor is relatively low, the loading of the doped metal on the carbon framework surface will be relatively small, resulting in a relatively weak enhancement of the electron transfer efficiency between microorganisms and electrodes. If the concentration of the metal-based ZIF precursor is relatively high, it will lead to a waste of raw materials.

[0058] In some embodiments of the present invention, the preparation method of the metal-based ZIF precursor includes: dissolving zinc nitrate and a metal salt in a second solvent to obtain a first mixture; dissolving 2-methylimidazole in a third solvent to obtain a second mixture; mixing and stirring the first mixture and the second mixture, and centrifuging to obtain the metal-based ZIF precursor.

[0059] In this step, the metal salt includes at least one of metal acetylacetonate, metal nitrate, and metal acetate; the second solvent and the third solvent are at least one of methanol and water, respectively.

[0060] S200: The cross-linked polymer solution is placed in a mold with a metal base and freeze-dried to obtain an aerogel with spatially oriented channels. In the freeze-drying process, the freezing process can induce the oriented and ordered growth of ice crystals in the solid polymer (the growth direction is from the base surface to the direction away from the base), and then through the drying process, the removal of ice crystals forms oriented and ordered pore channels in the polymer skeleton.

[0061] In some embodiments of the present application, the cross-linked polymer solution is placed in a mold, which can be a mold with a polytetrafluoroethylene side wall and a brass base. The good thermal conductivity of the metal brass in liquid nitrogen can induce the formation of ice crystals with directional growth. Further, the shape of the mold is not particularly required, and those skilled in the art can set it according to the requirements for the shape of the anode. In some specific embodiments, a cylindrical mold is used, so that a cylindrical spatially oriented channel anode can be prepared. This can facilitate the preparation of a columnar bioelectrochemical system, which can generate a more uniform self-generated electric field, and obtain better electricity generation performance and organic matter removal effect compared with a square bioelectrochemical system.

[0062] In some embodiments, the specific conditions of freeze-drying are not particularly required, and those skilled in the art can flexibly set them according to actual needs and actual situations. For example, freeze-drying can be carried out at -200℃ to -20℃.

[0063] In embodiments of the present application, the addition of the above-mentioned metal salt and metal-based ZIF precursor does not affect the directional growth process of the ice crystals.

[0064] S300: pyrolysis treatment of the aerogel to obtain a spatially oriented channel anode. In this way, the carbonization of the polymer skeleton is effectively realized by pyrolysis treatment, and a carbon skeleton is obtained.

[0065] According to some embodiments of the present application, the temperature of the pyrolysis treatment is 600℃ to 1200℃, such as 600℃, 650℃, 700℃, 750℃, 800℃, 850℃, 900℃, 950℃, 1000℃, 1100℃, 1200℃, etc., and the holding time is 1 to 4 hours. In this way, the polymer can be effectively carbonized.

[0066] In some embodiments, the heating rate of the pyrolysis treatment is 2 to 10℃ / min.

[0067] According to embodiments of the present application, the above-mentioned preparation method can effectively form unidirectional extended pore channels in the carbonized carbon skeleton, thereby effectively improving the spatial structure of the anode and increasing the specific surface area of the anode. When applied to a bioelectrochemical system, it can effectively increase the growth area of microorganisms on the surface of the anode. The carbon skeleton anode has the effect of efficient current collection, and is conducive to the directional transport of electrons and protons produced by microorganisms on the spatially oriented channel anode, thereby helping to improve its electrochemical activity. Moreover, after starting the bioelectrochemical system, the directional channel loaded with microorganisms can constitute a micro-channel reactor, which can strengthen the degradation effect of pollutants when the sewage flows through, and can improve the chemical energy conversion and in-situ self-driven resource recovery efficiency of the sewage.

[0068] In yet another aspect of the present application, the present application provides a bioelectrochemical system. According to embodiments of the present application, referring to Figure 1 and Figure 2 , the bioelectrochemical system comprises: an anode unit comprising at least one of the aforementioned spatially oriented channel anode 10, and the surface of the spatially oriented channel anode 10 is attached with electroactive microorganisms (not shown in the figure); an electrolyte; and a cathode unit 20, which is cylindrically arranged outside the anode unit 20. In this way, the anode of the bioelectrochemical system has a large area of microorganisms, so that the carbon skeleton anode has the effect of efficient current collection, and after the bioelectrochemical system is started, the oriented channel loaded with microorganisms can constitute a micro-channel reactor, which can strengthen the degradation effect of pollutants when the wastewater flows through, and can improve the chemical energy conversion and in-situ self-driven resource recovery efficiency of the wastewater.

[0069] The bioelectrochemical system (BES) combines electrochemical and biological principles to utilize the physiological metabolic processes of microorganisms on the electrode to achieve wastewater treatment and energy and resource recovery. When the bioelectrochemical system is working, microorganisms oxidize organic matter on the anode to produce electrons and protons, the electrons are transferred to the cathode through an external circuit, and the protons migrate to the cathode, and finally a reduction reaction occurs on the cathode.

[0070] According to some embodiments of the present application, referring to Figures 3 to 6 , the bioelectrochemical system further comprises: an ion exchange membrane, which comprises at least one layer of anion exchange membrane 32 and at least one layer of cation exchange membrane 31, and the ion exchange membrane is cylindrically arranged between the anode unit 10 and the cathode unit 20. In this way, the ion migration through the corresponding ion exchange membrane is driven by the electric field between the anode and the cathode, and the desalination / resource recovery effect is achieved.

[0071] According to some embodiments of the present application, referring to Figure 1 , Figure 6 and Figure 7 , the spatially oriented channel anode 10 is cylindrical, and further, the ion exchange membrane and / or the cathode unit 20 is cylindrically arranged around the spatially oriented channel anode 10. In this way, a more uniform self-generated electric field can be generated in the cylindrical bioelectrochemical system, and better electricity generation performance and organic matter removal effect can be obtained compared with the square bioelectrochemical system.

[0072] In some embodiments, the bioelectrochemical system further comprises a closed cover plate 40, as shown in Figure 2 , the closed cover plate 40 closes both sides of the cylindrical cathode unit 20, thereby obtaining a closed space defined by the closed cover plate 40 and the cathode unit. In some examples, the closed cover plate 40 can be organic glass.

[0073] In some embodiments, the bio-electrochemical system further comprises a closed cover plate 40, as shown in Figure 3 The closed cover plate 40 closes two sides of the cylindrical cathode unit 20, thereby forming an anode space defined by the closed cover plate 40 and the ion exchange membrane pair, a cathode space defined by the closed cover plate 40, the ion exchange membrane pair and the cathode unit 20, and a space between the ion exchange membrane pair. The sewage first enters the anode space and then enters the cathode space, and the space between the ion exchange membrane pair uses pure water or NaCl solution as the initial recovery liquid. In some examples, the closed cover plate 40 can be organic glass.

[0074] According to some embodiments of the present application, the anode unit comprises a plurality of spatially oriented channel anodes, which can be arranged in series and / or in parallel, and can specifically include the following three cases:

[0075] In some embodiments, referring to Figures 1 to 7 , the plurality of spatially oriented channel anodes 10 are arranged in series by the conductive wire 50. The number of the spatially oriented channel anodes 10 arranged in series is not limited, and can be flexibly selected by those skilled in the art according to actual needs, Figures 1 to 7 which is merely an example of 3 and 5 spatially oriented channel anodes 10 arranged in series.

[0076] In other embodiments, referring to Figure 8 , the plurality of spatially oriented channel anodes 10 are arranged in parallel by the conductive wire 50. The number of the spatially oriented channel anodes 10 arranged in parallel is not limited, and can be flexibly selected by those skilled in the art according to actual needs, Figure 8 which is merely an example of 3 spatially oriented channel anodes 10 arranged in parallel.

[0077] In yet other embodiments, referring to Figure 9 , the anode unit comprises a plurality of anode combinations 100 arranged in parallel (i.e., the plurality of anode combinations 100 are arranged in parallel by the conductive wire 50), and each anode combination 100 comprises a plurality of spatially oriented channel anodes 10 arranged in series. In this way, the multi-stage series anode configuration is further coupled, and a parallel anode configuration is designed, which can greatly improve the sewage treatment capacity of the anode unit and has good practical application prospects. The number of the spatially oriented channel anodes 10 in the anode combination 100 is not limited, and can be flexibly selected by those skilled in the art according to actual needs, and the number of the spatially oriented channel anodes 10 in different anode combinations 100 can be the same or different, Figure 9 which is merely an example of each anode combination 100 comprising 3 spatially oriented channel anodes 10 arranged in series and 3 anode combinations 100 arranged in parallel.

[0078] In yet another aspect of the present application, the present application provides a desalination system. According to embodiments of the present application, with reference to Figure 3 、 Figure 4 and Figure 10 , the desalination system comprises the bioelectrochemical system as described above, wherein the ion exchange membrane comprises a layer of anion exchange membrane 32 and a layer of cation exchange membrane 31, the anion exchange membrane 32 is cylindrically arranged around the space-oriented channel anode 10, and the anion exchange membrane 32 is arranged close to the space-oriented channel anode 10 relative to the cation exchange membrane 31; the cation exchange membrane 31 is cylindrically arranged around the side of the anion exchange membrane 32 away from the space-oriented channel anode 10, i.e. the cation exchange membrane 31 is arranged close to the cathode unit 20 relative to the anion exchange membrane 32. Thus, the desalination system can drive the migration of cations through the cation exchange membrane and the migration of anions through the anion exchange membrane by the electric field between the anode and the cathode, thereby effectively removing the ionic substances and achieving the desalination effect.

[0079] According to some embodiments of the present application, the desalination system can be used to remove the organic matters in the sewage and remove the ionic substances, specifically as follows:

[0080] In some embodiments, the desalination system is used to remove the organic matters in the sewage, and the influent substrate of the desalination system can be acetate, glucose substrate or municipal sewage. In some embodiments, the current output of the desalination system is arranged to be about 20-50 mA, and after treatment, the COD (chemical oxygen demand) of the effluent can be reduced to below 50 mg / L, the TN (total nitrogen) of the effluent of the desalination chamber is about below 15 mg / L, the ammonia nitrogen of the effluent is below 5 mg / L, and the TP (total phosphorus) of the effluent is below 0.5 mg / L.

[0081] In other embodiments, the desalination system is used to remove the ionic substances (such as sodium chloride), and when the NaCl concentration of the influent of the desalination chamber (the closed space defined between the closed cover plate 40 and the pair of ion exchange membranes) of the desalination system is about 10-30 g / L, the desalination rate can reach 60-70%.

[0082] In some embodiments of the present application, the desalinated water produced by the desalination system can be used as industrial boiler makeup water to ensure the safe and stable operation of the boiler and improve the energy utilization efficiency.

[0083] According to embodiments of the present application, the material of the cation exchange membrane can be sulfonic acid type polymer material, and the material of the anion exchange membrane can be quaternary amine type polymer material.

[0084] In yet another aspect of the present application, the present application provides a concentration system. According to embodiments of the present application, with reference to Figure 3 、 Figure 5 and Figure 11, the concentrating system comprises the bioelectrochemical system as described above, wherein the ion exchange membrane comprises a layer of anion exchange membrane 32 and a layer of cation exchange membrane 31, the cation exchange membrane 31 is cylindrically arranged around the space orientation channel anode 10, and the cation exchange membrane 31 is arranged close to the space orientation channel anode 10 relative to the anion exchange membrane 32; the anion exchange membrane 32 is cylindrically arranged around the side of the cation exchange membrane 31 away from the space orientation channel anode 10, i.e. the anion exchange membrane 32 is arranged close to the cathode unit 20 relative to the cation exchange membrane 31. Thus, the concentrating system can drive the migration of cations through the cation exchange membrane and the migration of anions through the anion exchange membrane by the electric field between the anode and the cathode, thereby effectively realizing the recovery of ionic substances (such as nitrogen and phosphorus), and thereby realizing the purification of wastewater and the concentration effect of resource substances.

[0085] According to some embodiments of the present application, the concentrating system can be used to realize the removal of organic matters in wastewater and the recovery of ionic substances, specifically as follows:

[0086] In some embodiments, the concentrating system is used for the removal of organic matters in wastewater, and the influent substrate of the concentrating system can be acetate, glucose substrate or municipal wastewater. In some embodiments, the concentrating system is arranged to output an electric current of about 20-50 mA, and after treatment, the COD (chemical oxygen demand) of the effluent can be reduced to below 50 mg / L, the TN (total nitrogen) of the effluent of the dilution chamber is about below 15 mg / L, the ammonia nitrogen of the effluent is below 5 mg / L, and the TP (total phosphorus) of the effluent is below 0.5 mg / L.

[0087] In other embodiments, the concentrating system is used for the concentration and recovery of ionic substances (such as nitrogen and phosphorus), and the concentrations of TN (total nitrogen), ammonia nitrogen and TP (total phosphorus) in the recovered liquid using the concentrating system are about 1.2-2.0 times, 1.2-2.0 times or even 2-3 times the concentrations in the original wastewater, thereby realizing effective enrichment and concentration of nutrients and achieving the purpose of resource recovery. In some embodiments of the present application, the recovered liquid produced by the concentrating system is rich in nitrogen and phosphorus substances, and can be used for irrigation and fertilization of flowers and vegetation, thereby effectively promoting the growth of plants.

[0088] In another aspect of the present application, a desalination-concentration composite system is provided. According to an embodiment of the present application, referring to Figure 6 and Figure 12 , the desalination-concentration composite system comprises the bioelectrochemical system as described above, wherein the ion exchange membrane comprises a plurality of layers of anion exchange membrane 32 and a plurality of layers of cation exchange membrane 31, and the plurality of layers of anion exchange membrane 32 and the plurality of layers of cation exchange membrane 32 are cylindrically arranged and sequentially overlapped between the space orientation channel anode 10 and the cathode unit 20. Thus, the system can simultaneously realize the purification of wastewater and the recovery of resources, and improve the treatment efficiency of pollutants.

[0089] The desalination-concentration composite system is based on the aforementioned desalination system and concentration system, and embeds multiple pairs of cation and anion exchange membranes. The anion exchange membranes 32 and the cation exchange membranes 32 are alternately arranged to form multiple desalination and concentration chambers (desalinated water is obtained in the desalination chamber, and concentrated liquid is obtained in the concentration chamber). When an electron passes through the external circuit of the system, a pair of cations and anions in each chamber migrate out of / in the membrane, thereby doubling the desalination / concentration rate of the system.

[0090] In some embodiments of the present application, the desalination-concentration composite system can embed 2-10 pairs of cation and anion exchange membranes. In some specific embodiments, after embedding 2-10 pairs of cation and anion exchange membranes in the desalination-concentration composite system, the average desalination rate per cycle can reach 100 mg / h-200 mg / h, and the average electron utilization efficiency can reach 450%-800%.

[0091] According to some embodiments of the present application, the desalination-concentration composite system adopts a stacked configuration, and the desalination and concentration effect of the desalination-concentration composite system is expected to be further improved, thereby widening its application range to the fields of agricultural fertilizer processing and finished product desalted water production.

[0092] In another aspect of the present application, the present application provides the application of the aforementioned desalination system, concentration system or desalination-concentration system in sewage purification and nitrogen and phosphorus recovery.

[0093] Embodiments

[0094] The method for preparing the spatially oriented channel anode comprises:

[0095] 10 mmol of zinc nitrate hexahydrate and 5 mmol of iron (III) acetylacetonate were dissolved in 100 mL of methanol to obtain a first mixed solution, and 80 mmol of 2-methylimidazole was dissolved in 100 mL of methanol solution to obtain a second mixed solution. The first mixed solution was mixed with the second mixed solution, continuously stirred for 1 h and then left standing overnight. The Fe-ZIF precursor was collected by centrifugation and drying.

[0096] The chitosan powder, water and acetic acid were mixed and stirred for 24 h, and then 0.2 g of the Fe-ZIF precursor (or without adding) was added to obtain a cross-linked polymer solution;

[0097] The cross-linked polymer solution was placed in a cylindrical mold with a polytetrafluoroethylene side wall and a brass base (i.e., the prepared anode is cylindrical, and a cylindrical bioelectrochemical system is obtained) for freeze-drying. During the freezing process, ice crystals grow in an ordered orientation, and during the drying process, the ice crystals are removed, and then a spatially oriented ordered pore channel, i.e., a spatially oriented channel aerogel, is obtained.

[0098] The aerogel with spatially oriented channels was pyrolyzed at 1000℃ for 2 hours at a temperature increasing rate of 5℃ / min in an argon atmosphere to obtain an iron-doped spatially oriented channel anode, denoted as Fe-NDCF-x (x is the proportion of polymer in the cross-linked polymer solution), and a spatially oriented channel anode without the introduction of iron elements, denoted as DCF-x. The spatially oriented channel anode has a diameter of 3 cm and a thickness of 0.5 cm.

[0099] In Examples 1 to 6, the mass concentration of the polymer in the cross-linked polymer solution and the doping metal can be seen in Table 1.

[0100] Table 1

[0101]

[0102] Comparative Example 1

[0103] A graphite plate (GP) was used as the anode of the bio-electrochemical system.

[0104] Comparative Example 2

[0105] A carbon felt (CF) was used as the anode of the bio-electrochemical system.

[0106] The spatially oriented channel anodes obtained in Examples 1 to 6 were tested for performance, as follows:

[0107] Scanning electron microscopy:

[0108] The surfaces of the spatially oriented channel anodes obtained in Examples 1 to 6 were respectively scanned by scanning electron microscopy, and the scanning electron microscopy images and EDS spectra can be respectively referred to (a) to (f) in Figure 13 It can be seen from Figure 13 that the surface of the spatially oriented channel anode is a uniform pore distribution structure, indicating that the directional induction of the pore channel is successful, and as the concentration of the polymer solution increases, the internal structure of the spatially oriented channel anode is more compact.

[0109] The vertical cross sections of the spatially oriented channel anodes obtained in Examples 1 to 6 were respectively scanned by scanning electron microscopy, and the scanning electron microscopy images and EDS spectra can be respectively referred to (a) to (f) in Figure 14 It can be seen from Figure 14 that the cross section of the spatially oriented channel electrode is lamellar.

[0110] Moreover, it can be seen from (b), (d) and (f) in Figure 13 and (b), (d) and (f) in Figure 14 that the addition of the Fe-ZIF precursor in the cross-linked polymer solution successfully realizes the attachment of the metal on the surface of the carbon skeleton.

[0111] Electrochemical performance:

[0112] The spatially oriented channel anodes obtained in Examples 1 to 6 were respectively subjected to conductivity tests, and the test results can be seen from Table 1 Figure 15 The spatially oriented channel anodes obtained in Examples 1 to 6 and the anodes in Comparative Examples 1 and 2 were respectively subjected to electrochemical activity tests, and the test results can be seen from Table 2 Figure 16 .

[0113] Figure 15 It can be shown that the Fe-NDCF-3 anode has the best conductivity, and as the mass concentration of the polymer increases, the carbon skeleton inside the anode is more compact, and more pore channels are formed, thereby improving the conductivity of the anode, and the introduction of iron can further improve the conductivity.

[0114] As shown in Table 2 Figure 16 , the Fe-NDCF-3 anode has the best electrochemical activity, with the highest redox current density, and is much superior to the electrochemical activity of the anodes in Comparative Examples 1 and 2. The maximum oxidation current density of the Fe-NDCF-3 anode is 128.6 A / m 2 , which is 2.2 times that of the DCF-3 anode (the maximum oxidation current density is 58.9 A / m 2 ), indicating that the introduction of metal active sites effectively enhances the electrochemical activity of the spatially oriented channel anode. In contrast, the oriented channel anodes prepared from the precursor solution with a lower polymer concentration have relatively low redox activity. The maximum oxidation current densities of the Fe-NDCF-2, DCF-2, Fe-NDCF-1, and DCF-1 anodes are 74.5 A / m 2 , 5.7 A / m 2 , 11.6 A / m 2 , and 0.5 A / m 2 , respectively. It can be seen that the formation of the conductive skeleton inside the carbon-based skeleton anode can effectively promote the electrocatalytic activity of the electrode.

[0115] The specific capacitances of different anodes were calculated by CV curves, as shown in (b) of Table 2 Figure 16 . As the polymer concentration increases, the conductive skeleton inside the anode gradually forms, and the specific capacitance of the anode significantly improves. The specific capacitance of the Fe-NDCF-3 anode is 2.5 times and 68 times higher than that of the Fe-NDCF-2 anode and the Fe-NDCF-1 anode, respectively, and the specific capacitance of the DCF-3 anode is 5.4 times and 153 times higher than that of the DCF-2 anode and the DCF-1 anode, respectively. The specific capacitance of the Fe-NDCF-3 anode is 2 times that of the DCF-3 anode.

[0116] The internal resistance of each anode was measured by EIS test, as shown in Table 3 Figure 16It can be seen that the charge transfer resistance accounts for the main part in (c) and (d) in the table. With the gradual formation of the conductive framework, the internal resistance of the anode decreases significantly. The charge transfer resistance of the DCF-1 anode is 826.5 Ω, the charge transfer resistance of the DCF-2 anode is 55.2 Ω, the charge transfer resistance of the DCF-3 anode is 15.5 Ω, and the charge transfer resistance of the Fe-NDCF-3 anode is 8.9 Ω, which is the lowest.

[0117] Electrochemical performance of the anode after loading microorganisms:

[0118] The anode surface in Examples 1-6 and Comparative Examples 1 and 2 is loaded with microorganisms to obtain an anode biofilm, and the anode biofilm is a mixed microbial biofilm with Geobacter and other electroactive microorganisms as important components. The CV curve of each bioanode after loading microorganisms is tested for bioelectrochemical activity, and the test results can be referred to Figure 17 It can be seen that the Fe-NDCF-3 bioanode has the best substrate oxidation intensity, and the maximum oxidation current reaches 31.5 A / m 2 , which is 1.7 times the maximum oxidation current (19.1 A / m 2 ) of the DCF-3 bioanode, and the maximum oxidation current of the Fe-NDCF-2 bioanode is 21.7 A / m 2 , which is 1.7 times the maximum oxidation current (12.5 A / m 2 ) of the DCF-2 bioanode, and the maximum oxidation current of the Fe-NDCF-1 bioanode reaches 18.3 A / m 2 , which is 2.4 times the maximum oxidation current (7.7 A / m 2 ) of the DCF-1 bioanode.

[0119] Polarization curve test:

[0120] The anodes in Examples 1-6 and Comparative Examples 1 and 2 are assembled to obtain a bioelectrochemical system without an ion exchange membrane, as shown in Figure 1 , wherein the simulated influent uses 1 g / L sodium acetate as the substrate, the electrolyte is phosphate buffer solution (PBS), and 5.0 mL / L vitamin solution and 12.5 mL / L mineral solution are added to maintain the growth needs of microorganisms, and the cathode is an air cathode, which includes a carbon black diffusion layer, an activated carbon carbon black composite catalytic layer, and a stainless steel mesh current collector. The anode biofilm is a mixed microbial biofilm with Geobacter and other electroactive microorganisms as important components. The external resistance of the bioelectrochemical system is adjusted from 5000 Ω to 2 Ω step by step, and is stabilized for 20 min respectively, and the output voltage and anode potential are recorded to obtain the polarization curve, and the test results can be referred to Figure 18 .

[0121] The power generation performance of the anode bioelectrochemical system of different spatial orientation channels can be obtained by the polarization curve, and the test results can be referred toFigure 18 The maximum power density of the bioelectrochemical system with Fe-NDCF-3 anode reached 3018±133 mW / m 2 , which was 142% of the maximum power density (2130±105 mW / m 2 ) of the bioelectrochemical system with DCF-3 anode, and the maximum power densities of the bioelectrochemical systems with Fe-NDCF-2 and Fe-NDCF-1 anodes were about 1979±124 mW / m 2 and 1228±100 mW / m 2 , respectively, which were about 31% and 115% higher than the bioelectrochemical systems with DCF-2 (1516±77 mW / m 2 ) and DCF-1 (571±28 mW / m 2 ) anodes, respectively. Meanwhile, the maximum current density of the bioelectrochemical system with Fe-NDCF-3 anode was 20.5 A / m 2 , which was obviously superior to all the bioelectrochemical systems, while the maximum current density of the bioelectrochemical system with DCF-1 anode was only 2.3 A / m 2 .

[0122] Test of pollutant removal performance and substrate utilization efficiency of the bioelectrochemical system:

[0123] The bioelectrochemical systems without ion exchange membrane were assembled respectively with the anodes in Examples 1-6 and Comparative Examples 1 and 2, as shown in Figure 1 and Figure 2 , wherein the simulated influent used 1 g / L sodium acetate as the substrate, the electrolyte was phosphate buffer solution (PBS), and 5.0 mL / L vitamin solution and 12.5 mL / L mineral solution were added to maintain the need of microbial growth, the cathode was an air cathode which included carbon black diffusion layer, activated carbon and carbon black composite catalytic layer, and stainless steel mesh current collector, and the anode biofilm was a mixed microbial biofilm with Geobacter and other electroactive microorganisms as important components.

[0124] The obtained bioelectrochemical systems were tested for pollutant removal performance and substrate utilization efficiency, and the test results can be referred to Figure 19 . As can be seen from (a) in Figure 19 , the COD degradation effect in the Fe-NDCF-3 BES was obviously superior to those of other bioelectrochemical systems, and the effluent COD was about 32 mg / L at the end of the cycle, and the organic matter was effectively removed. The organic matter degradation of all the bioelectrochemical systems was fitted by first-order kinetics, as shown in (b) and (c) in Figure 19 , and the organic matter removal rate constant of the Fe-NDCF-3 BES was 0.23±0.01 h -1, 15% and 35% higher than Fe-NDCF-2 BES (0.20 ± 0.02 h -1 ) and Fe-NDCF-1 BES (0.17 ± 0.01 h -1 ), respectively, and the organic matter degradation performance was better than that of the corresponding control anode. As shown in (d) of Figure 19 , the coulombic efficiencies of DCF-1 BES, Fe-NDCF-1 BES, DCF-2 BES, Fe-NDCF-2 BES, DCF-3 BES and Fe-NDCF-3 BES were 27%, 31%, 34%, 50%, 50% and 74%, respectively, indicating that the bioelectrochemical activity of the spatially oriented channel anode was improved with the densification of the internal carbon skeleton, and the conversion of organic matter to electrical energy was promoted.

[0125] The relationship between the current density and the organic matter concentration in different bioelectrochemical systems was analyzed, as shown in Figure 20 , the Fe-NDCF-3 bioanode could produce higher current density than the control at the same organic matter concentration, especially in the low organic matter concentration region below 200 mg / L, indicating that it had the optimal conversion efficiency of organic matter to electrical energy.

[0126] Stability test:

[0127] The anodes in Examples 5 (DCF-3) and 6 (Fe-NDCF-3) were assembled into bioelectrochemical systems without ion exchange membranes, as shown in Figure 1 and Figure 2 , wherein 1 g / L sodium acetate was used as the substrate in the simulated influent, phosphate buffer (PBS) was used as the electrolyte, and 5.0 mL / L vitamin solution and 12.5 mL / L mineral solution were added to maintain the growth of microorganisms, the cathode was an air cathode including a carbon black diffusion layer, an activated carbon carbon black composite catalyst layer and a stainless steel mesh current collector, and the anode biofilm was a mixed microbial biofilm with Geobacter and other electroactive microorganisms as important components.

[0128] The stability of the obtained bioelectrochemical systems under long-term continuous operation was evaluated, and the results are shown in Figure 21 . From the long-term current density curve, it can be seen that the Fe-NDCF-3 BES and DCF-3 BES both maintained a relatively stable current output during continuous operation, indicating that these bioelectrochemical systems had good running stability.

[0129] Example 7

[0130] The difference from Example 6 is that the cathode unit is arranged in a square on the opposite side of the anode unit, i.e., the obtained bioelectrochemical system is square.

[0131] The power generation performance of the cylindrical bio-electrochemical system and the square bio-electrochemical system is tested respectively, as shown in Figure 22 It can be seen from the above that the power density of the cylindrical bio-electrochemical system is better than that of the square bio-electrochemical system, indicating that the cylindrical bio-electrochemical system has a better conversion efficiency of organic matter to electrical energy.

[0132] The terms "first", "second", etc. are used only for the purpose of description, and cannot be understood as indicating or implying relative importance or implicitly indicating the number of the indicated technical features. Therefore, the features defined with "first", "second" can explicitly or implicitly include one or more of the features. In the description of the present application, the meaning of "a plurality of" is two or more, unless otherwise specifically limited.

[0133] In the description of the present application, the description of the terms "one embodiment", "some embodiments", "example", "specific example", or "some examples" means that the specific features, structures, materials or characteristics described in connection with the embodiment or example are included in at least one embodiment or example of the present application. In the present application, the illustrative description of the above terms does not necessarily refer to the same embodiment or example. Moreover, the specific features, structures, materials or characteristics described can be combined in any appropriate manner in any one or more embodiments or examples. In addition, different embodiments or examples described in the present application and the features of different embodiments or examples can be combined and combined by those skilled in the art without contradiction.

[0134] Although the embodiments of the present application have been shown and described above, it can be understood that the above embodiments are exemplary and cannot be understood as limiting the present application, and those skilled in the art can make changes, modifications, replacements and variations to the above embodiments within the scope of the present application.

Claims

1. A method for preparing a spatially oriented channel anode, characterized in that, include: The polymer powder is mixed with a first solvent and adjusted to acidity to obtain a cross-linked polymer solution, wherein the polymer includes at least one of chitosan, sodium alginate, and polyvinyl alcohol; A metal salt and / or a metal-based ZIF precursor are added to the crosslinked polymer solution, wherein the metal salt is a transition metal salt, including at least one of transition metal nitrates and transition metal acetates; The cross-linked polymer solution was placed in a mold with a metal base and freeze-dried to obtain an aerogel with spatially oriented channels. The aerogel is subjected to pyrolysis treatment to obtain the spatially oriented channel anode. The pyrolysis treatment temperature is 600℃~1200℃ and the holding time is 1~4 hours.

2. The method according to claim 1, characterized in that, At least one of the following conditions must be met: The mass concentration of the polymer in the crosslinked polymer solution is 0.25% to 5%; The heating rate of the pyrolysis treatment is 2~10℃ / min.

3. The method according to claim 1, characterized in that, Based on the total mass of the polymer, the mass concentration of the metal salt in the crosslinked polymer solution is 0.1% to 5%; And / or, based on the total mass of the polymer, the mass concentration of the metal-based ZIF precursor in the crosslinked polymer solution is 0.1% to 2%. And / or, the method for preparing the metal-based ZIF precursor includes: Zinc nitrate and a metal salt are dissolved in a second solvent to obtain a first mixture; 2-Methylimidazole was dissolved in a third solvent to obtain a second mixture; The first mixture and the second mixture were mixed and stirred, and then centrifuged to obtain the metal-based ZIF precursor.

4. A spatially oriented channel anode, characterized in that, It is prepared by the method according to any one of claims 1 to 3, comprising: A carbon skeleton having pore channels that extend in one direction; A doped metal, which is attached to the surface of the carbon framework, including a transition metal.

5. A bioelectrochemical system, characterized in that, include: An anode unit comprising at least one spatially oriented channel anode as described in claim 4, or a spatially oriented channel anode prepared by the method of any one of claims 1 to 3, wherein the surface of the spatially oriented channel anode is coated with electroactive microorganisms; Electrolytes; A cathode unit, which is columnar and arranged around the outside of the anode unit.

6. The bioelectrochemical system according to claim 5, characterized in that, Also includes: An ion exchange membrane, comprising at least one anion exchange membrane and at least one cation exchange membrane, wherein the ion exchange membrane is arranged in a columnar shape between the anode unit and the cathode unit.

7. The bioelectrochemical system according to claim 6, characterized in that, The anode unit includes a plurality of spatially oriented channel anodes, and the anode unit satisfies one of the following conditions: Multiple spatially oriented channel anodes are connected in series via conductive wires; Multiple spatially oriented channel anodes are connected in parallel via the conductive wires; The anode unit includes multiple parallel anode combinations, and each anode combination includes multiple spatially oriented channel anodes arranged in series; The anode of the spatial directional channel is cylindrical.

8. The bioelectrochemical system according to claim 6, characterized in that, The cathode unit and / or the ion exchange membrane are cylindrical.

9. A desalination system, characterized in that, The bioelectrochemical system comprising any one of claims 6 to 8, wherein the ion exchange membrane comprises an anion exchange membrane and a cation exchange membrane, the anion exchange membrane being cylindrically disposed around the spatially oriented channel anode and close to the spatially oriented channel anode, and the cation exchange membrane being cylindrically disposed around the side close to the cathode unit.

10. A concentration system, characterized in that, The bioelectrochemical system comprising any one of claims 6 to 8, wherein the ion exchange membrane comprises an anion exchange membrane and a cation exchange membrane, the cation exchange membrane being cylindrically disposed around the spatially oriented channel anode and close to the spatially oriented channel anode, and the anion exchange membrane being cylindrically disposed around the side close to the cathode unit.

11. A desalination-concentration composite system, characterized in that, The bioelectrochemical system comprising any one of claims 6 to 8, wherein the ion exchange membrane comprises multiple anion exchange membranes and multiple cation exchange membranes, and the multiple anion exchange membranes and multiple cation exchange membranes are all cylindrical and sequentially overlapped between the anode and cathode units of the spatially oriented channel.

12. The application of the desalination system of claim 9, the concentration system of claim 10, or the desalination-concentration system of claim 11 in wastewater purification and resource recovery.

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