Light-driven dual-cathode bioelectrochemical reactor and application thereof

Abstract

The present application relates to the field of electrochemistry, and discloses a light-driven bioelectrochemical reactor and application thereof. The reactor is provided with a working electrode in each of cathode chamber I and cathode chamber II, which are located on both sides of an anode chamber and are separated from the anode chamber by an anion exchange membrane and an anion exchange membrane respectively; the anode chamber is provided with a counter electrode containing a bacterial population, and the working electrodes are connected in parallel with the two counter electrodes through an external resistance; the working electrode is made of a cobalt / molybdenum disulfide nanocarbon photoelectrocatalyst and is used for absorbing visible light and generating electrons; under the driving of visible light, the bioelectrochemical reactor produces hydrogen in cathode chamber I and oxidizes wastewater containing organic matter in cathode chamber II. The light-driven double-cathode-chamber bioelectrochemical system designed in the present application can realize the effect of simultaneous hydrogen production and wastewater treatment, and can improve the wastewater treatment efficiency and hydrogen production rate, realize the combination of organic wastewater treatment and energy recovery, and achieve sustainable utilization of resources.

Description

Technical Field

[0001] This invention relates to the field of electrochemical technology, specifically to a light-driven dual-cathode bioelectrochemical reactor and its applications. Background Technology

[0002] The discharge of antibiotic wastewater is a common problem in modern industrial production and pharmaceutical applications. Its high concentration of organic matter and antibiotic residues cause serious pollution and harm to the environment and water resources. Traditional wastewater treatment methods often require high energy consumption and complex operating procedures, making it difficult to achieve complete degradation of wastewater and resource recovery.

[0003] CN106745675A discloses a bioelectrochemical device and its working method for treating antibiotic wastewater. The device includes multiple structures such as a bed, a DC power supply, a raw water storage tank, a mixing tank, a heating device, an ejector, an electrolysis promoter storage device, and an enzyme activity regulator storage device. It uses a bioelectrochemical SBBR reactor to couple the treatment of antibiotic wastewater, but it has problems such as complex equipment structure and high energy consumption in the treatment process.

[0004] Meanwhile, the development and utilization of clean energy has become a global focus, with hydrogen, as a highly efficient and environmentally friendly energy source, showing great potential. Electrocatalysis and biocatalysis are important research directions in the fields of wastewater treatment and energy conversion.

[0005] However, in existing technologies, organically integrating electrocatalysis and biocatalysis to simultaneously treat wastewater and generate clean hydrogen remains challenging. Therefore, an innovative method is needed that, driven by renewable energy, can efficiently and stably treat antibiotic wastewater while simultaneously generating hydrogen, thereby achieving wastewater purification and clean energy production.

[0006] CN105555715A discloses a bioelectrochemical system capable of removing multivalent ions. The system includes an oxidation electrode cell, a reduction electrode cell, an anion exchange membrane, and a power source. The oxidation electrode cell has an anode with electrochemically active bacteria attached, which oxidizes organic matter to generate electrons. The reduction electrode cell has a cathode that removes multivalent ions while producing hydrogen. The anion exchange membrane separates the oxidation and reduction electrode cells and prevents multivalent cations from migrating to the oxidation electrode cell. This system can remove multivalent ions present in seawater and other sources while producing hydrogen. However, the cathode system in this design suffers from low overall efficiency due to the impact of multivalent ion removal on hydrogen production efficiency. Summary of the Invention

[0007] This invention addresses the shortcomings of existing technologies, such as the limited removal performance of simple antibiotic pollutants and the slow development of bifunctional bioelectrochemical reactors. It provides a light-driven bioelectrochemical reactor that can achieve homogeneous hydrogen production in the treatment of antibiotic wastewater under light-driven conditions, thus achieving the dual goals of environmental protection and energy utilization with excellent results.

[0008] To achieve the above objectives, the technical solution adopted by the present invention is as follows:

[0009] A light-driven dual-cathode bioelectrochemical reactor includes a cathode chamber I, an anode chamber, a cathode chamber II, an external resistor, and a visible light source;

[0010] Both cathode chamber I and cathode chamber II are equipped with working electrodes located on both sides of the anode chamber, and are separated from the anode chamber by anion exchange membrane and cation exchange membrane, respectively; the anode chamber is equipped with counter electrodes containing bacteria, and the working electrode is connected in parallel with the two counter electrodes via an external resistor;

[0011] The working electrode is made of cobalt / molybdenum disulfide nano-carbon photoelectrocatalyst, which is used to absorb visible light and generate electrons; under visible light drive, the dual-cathode bioelectrochemical reactor generates hydrogen in cathode chamber I and oxidizes wastewater containing organic matter in cathode chamber II.

[0012] This invention utilizes a bioelectrochemical reactor with dual cathodes on both sides of the bioanode chamber, separating the anode and cathode chambers using cation exchange and anion exchange membranes. Within the anode chamber, wastewater containing organic matter is introduced and undergoes microbial decomposition and oxidation, being degraded into small-molecule organic compounds such as acids, ketones, and aldehydes.

[0013] In the dual-photocatalyst chambers connected in parallel on both sides, a cobalt / molybdenum disulfide nano-carbon photocatalyst is used as the working electrode to convert visible light energy into electrical energy. In cathode chamber II, the photogenerated electrons generated after light energy absorption activate water in alkaline wastewater, dissolving oxygen molecules to generate superoxide radicals, which further oxidize and decompose organic matter in the wastewater. In cathode chamber I, the photogenerated electrons, under the coupling effect of bioelectrons in the anode chamber, catalyze the oxidation reaction of water molecules to generate hydrogen gas, thus achieving the effect of simultaneously treating wastewater containing organic matter and producing hydrogen. The efficiency of the catalytic reaction in each of the dual cathodes can be adjusted by regulating the light intensity and the external resistance value in the dual cathode reaction chambers.

[0014] In a dual-cathode system, the electron flow can be distributed between the two cathode chambers according to different reaction requirements. The electron flow in the first cathode chamber promotes reduction or indirect oxidation reactions in the wastewater, while the electron flow in the second cathode chamber promotes the reduction reaction for hydrogen production. This parallel electron flow distribution ensures the smooth progress of both reactions, enabling the system to achieve optimal efficiency. This synergistic effect not only improves wastewater treatment efficiency but also provides a sustainable energy recovery pathway, combining wastewater treatment with energy generation, and possesses both environmental and economic potential.

[0015] The method for preparing the cobalt / molybdenum disulfide nanocarbon photocatalyst includes the following steps:

[0016] The cobalt / molybdenum disulfide nanocarbon photocatalyst was obtained by dissolving cobalt salt, tetrathiomolybdate, and biocarbon material, followed by hydrothermal reaction, washing and drying the product, and then calcining it under a reducing atmosphere.

[0017] The molar ratio of the cobalt salt and the tetrahexamolybdate is 1-4:4;

[0018] The molar ratio of graphene to tetrahexamolybdate is 5-10:1;

[0019] The hydrothermal reaction temperature is 150-250℃, and the reaction time is 18-24h.

[0020] The calcination temperature is 600-900℃, and the calcination time is 1-3h.

[0021] The reducing atmosphere is a mixture of hydrogen and an inert gas, wherein the hydrogen volume percentage is 5-15%.

[0022] The cobalt salts include cobalt nitrate hexahydrate and cobalt chloride hexahydrate, and the tetrathiomolybdate is ammonium tetrathiomolybdate.

[0023] The preparation process of the working electrode includes: grinding the cobalt / molybdenum disulfide nano-carbon photoelectrocatalyst and then coating the solution onto a titanium sheet to obtain the working electrode.

[0024] The illuminance of the visible light source is 0-50 mW / cm². -2 The resistance value of the external resistor is 10-1000Ω.

[0025] Preferably, the illuminance of the visible light source is 10-50 mW / cm². -2 Further optimization of 40mW cm -2 The resistance value of the external resistor is 10-100Ω.

[0026] The cathode chamber I and cathode chamber II are each independently equipped with a visible light source. The dual-cathode bioreactor of this invention can also operate independently, with visible light sources on both sides, allowing for free control of whether one side operates or not.

[0027] The present invention also provides the application of the light-driven bioelectrochemical reactor in the treatment of wastewater containing levofloxacin, wherein the bioelectrochemical reactor can produce hydrogen gas while treating the wastewater.

[0028] This invention achieves simultaneous treatment of antibiotic wastewater and hydrogen generation by introducing wastewater containing organic matter, particularly antibiotics, into the anode and cathode chambers I respectively for oxidative degradation, and then using a parallel dual-light-driven cathode reaction chamber for photocatalytic reduction. This method not only helps solve wastewater pollution problems but also effectively recovers and utilizes the energy generated during wastewater treatment, exhibiting environmental protection and sustainability characteristics. Compared to a single cathode catalytic system, the dual-cathode coupling system in this invention offers higher wastewater treatment efficiency, energy recovery capacity, and improved overall performance, making wastewater treatment and energy utilization more coordinated and providing potential for environmentally friendly technological innovation.

[0029] Preferably, the wastewater after preliminary oxidation and degradation in the anode chamber can be introduced into the cathode chamber I for further oxidation and degradation, resulting in a more complete and thorough treatment effect.

[0030] The photo-driven bioelectrochemical system for treating antibiotic wastewater and simultaneously producing hydrogen provided by this invention achieves a synergistic effect between the two reactions of wastewater treatment and hydrogen production through the interaction of electron flow and intermediate products. This synergy not only improves wastewater treatment efficiency but also provides a sustainable energy recovery pathway, combining wastewater treatment with energy generation, and has both environmental and economic potential.

[0031] Compared with the prior art, the present invention has the following beneficial effects:

[0032] (1) The bioelectrochemical system with a light-driven dual cathode chamber designed in this invention can achieve the effect of simultaneous hydrogen production in the treatment of wastewater containing organic matter, and improve the treatment effect of wastewater. Wastewater containing organic matter is treated simultaneously in the anode chamber and cathode chamber I, and the treatment efficiency is significantly improved.

[0033] (2) The bioelectrochemical system of the photo-driven dual cathode chamber of the present invention also improves the energy recovery method, combines organic wastewater treatment with energy recovery, and realizes the sustainable use of resources.

[0034] (3) The photo-driven bioelectrochemical system for treating antibiotic wastewater and simultaneously generating hydrogen provided by this invention, through the coupling of a dual-cathode system, is not only a wastewater treatment system but also has the function of energy generation. This multifunctionality can meet the needs of different application scenarios to a certain extent. For example, in situations where regional resources are scarce or environmental pollution is severe, it can effectively solve the problems of wastewater treatment and energy supply. Attached Figure Description

[0035] Figure 1 The image shows a scanning electron microscope (SEM) image of the Co-MoS2 / NC catalyst prepared in Example 1.

[0036] Figure 2 The dual-cathode bioelectrochemical reactor constructed in Example 1.

[0037] Figure 3 To test the change of current in cathode chambers I-II of the reactor under illumination or no illumination in Application Example 1.

[0038] Figure 4 This is a graph showing the relationship between the pollutant degradation kinetics in cathode chamber I and the light intensity in application example 2.

[0039] Figure 5 The graph shows the relationship between the potential of cathode chamber II and the light intensity in Application Example 2.

[0040] Figure 6 This serves as a comparison of the efficiency of cathode chamber I and cathode chamber II operating individually or together in Application Example 2.

[0041] Figure 7 This is a comparison diagram of the pollutant degradation kinetics in bioelectrochemical reactors with different working electrodes used in Example 3. Detailed Implementation

[0042] To make the objectives, technical solutions, and advantages of this invention clearer, the invention will be further described in detail below with reference to embodiments. It should be understood that the specific embodiments described herein are merely illustrative and not intended to limit the invention. Modifications or equivalent substitutions made by those skilled in the art based on their understanding of the technical solutions of this invention, without departing from the spirit and scope of the invention, should be covered within the protection scope of this invention.

[0043] All raw materials used in the following specific implementation methods were purchased from the market.

[0044] Example 1

[0045] Step 1: Weigh 35 mg of cobalt nitrate hexahydrate solid particles and 120 mg of ammonium tetrathiomolybdate solid particles, dissolve them in 60 mL of deionized water, and sonicate for 10 min; add 80 mg of graphene material and stir until homogeneous.

[0046] Step 2: Place the solution from Step 1 in a reaction vessel and hydrothermally heat it at 200°C for 18 hours. After the reaction is complete, cool and centrifuge. Wash the product with deionized water and dry it to obtain the cobalt-doped molybdenum disulfide catalyst precursor.

[0047] Step 3: The cobalt-doped molybdenum disulfide catalyst precursor was calcined at high temperature in a tube furnace under a H2 / Ar (10% / 90%) atmosphere at 800℃ for 1 hour. After the reaction was complete, it was cooled to room temperature to obtain the cobalt / molybdenum disulfide nanocarbon catalyst, denoted as Co-MoS2 / NC. Its microstructure was observed, as follows: Figure 1 As shown, from Figure 1 Cobalt-doped molybdenum disulfide nanosheets can be seen distributed on the surface of the carbon material.

[0048] Step 4: Apply Co-MoS2 / NC to the polished titanium sheet (1*1cm). 2 The working electrode 6 is placed in cathode chamber I (2) and cathode chamber II (3) respectively, and the anode chamber 1 is separated by anion exchange membrane 5 and cation exchange membrane 4; a carbon rod as counter electrode 7 is provided in anode chamber 1, and microbial flora grows in it, located between cathode chamber I (2) and cathode chamber II (3). The working electrode 6 in the cathode chamber is connected in parallel with the counter electrode 7 in the anode chamber through an external resistor 8. Both cathode chamber I and cathode chamber II are equipped with visible light sources; the volume of anode chamber, cathode chamber I, and cathode chamber II is 15 mL; the reference electrode 9 is a saturated Ag / AgCl electrode; after assembly, the following is obtained: Figure 2 The light-driven dual-cathode bioelectrochemical reactor shown is an example.

[0049] Comparative Example 1

[0050] According to the preparation process of Example 1, no graphene material is added in step 1. Cobalt-doped molybdenum disulfide photocatalyst is obtained through hydrothermal reaction and calcination reduction. The working electrode is prepared from it and used in a light-driven dual-cathode bioelectrochemical sequence reactor.

[0051] Comparative Example 2

[0052] Following the preparation process of Example 1, without adding graphene material and cobalt nitrate hexahydrate in step 1, molybdenum disulfide photoelectrocatalyst was obtained through hydrothermal reaction and calcination reduction, and used to prepare working electrode for photo-driven dual-cathode bioelectrochemical reactor.

[0053] Application Example 1

[0054] Step 1: Under room temperature and pressure conditions, simulated wastewater containing 10 mg / L of the antibiotic levofloxacin is introduced into the anode chamber and cathode chamber I of the light-driven dual-cathode bioelectrochemical reactor, and 0.1 M Na2SO4 electrolyte is introduced into cathode chamber II; the reference electrode is a saturated Ag / AgCl electrode.

[0055] Step 2: Use the 16-channel data acquisition board (MPS-010602) to test the results of anodic acclimation. Do not start the visible light driving reactor. The reactor can only start testing the dual-cathode activity after the anodic potential has stabilized.

[0056] At 40W / cm 2 Under light intensity irradiation, the output current under the working electrode of Example 1 was measured, and the reactor current density was determined. The results are as follows: Figure 3 As shown, the output current of the entire reactor is more than twice that when the light is turned on compared to when the light is turned off, which is a significant effect.

[0057] Application Example 2

[0058] After the anodic potential stabilizes, the catalytic performance of the cathode chamber is tested under different light intensities. During the test, the light in the cathode chamber on the side not being tested is turned off.

[0059] The relationship between the degradation kinetic constant of levofloxacin in wastewater in cathode chamber I and light intensity is as follows: Figure 4 As shown, the degradation kinetic constant increases linearly with changes in light intensity, but when the light intensity reaches 50 mW / cm², the degradation kinetic constant decreases. 2 At this point, the catalytic performance begins to weaken, indicating that excessively high light intensity begins to affect the activity of organisms.

[0060] The relationship between the potential in cathode chamber II and the light intensity is as follows: Figure 5 As shown, the cathode potential becomes more negative as the light intensity increases, which is more conducive to the spontaneous generation of hydrogen.

[0061] Figure 6 This study compares the pollutant removal efficiency of cathode chamber I when operating alone and with both cathodes, as well as the hydrogen production rate of cathode chamber II when operating alone and with both cathodes operating simultaneously. It is evident that both the pollutant removal rate and the hydrogen production rate are significantly improved when both cathodes operate simultaneously, demonstrating the synergistic effect of the dual cathode chambers, which promotes both the pollutant removal speed and the hydrogen production rate.

[0062] Application Example 3

[0063] Using Example 1, Comparative Examples 1-2, and pure titanium sheets without any catalyst loading as working electrodes, both cathodes were at 40 mW / cm². 2Under illumination, the degradation kinetic constants of levofloxacin in a dual-cathode bioelectrochemical reactor were tested, and the results are as follows: Figure 7 As shown, the working electrodes prepared with different catalysts have different effects, among which the working electrode prepared with Co-MoS2 / NC catalyst has a better effect.

Claims

1. A light-driven dual-cathode bioelectrochemical reactor, characterized in that, Includes cathode chamber I, anode chamber, cathode chamber II, external resistor, and visible light source; Both cathode chamber I and cathode chamber II are equipped with working electrodes located on both sides of the anode chamber, and are separated from the anode chamber by anion exchange membrane and cation exchange membrane, respectively; the anode chamber is equipped with a counter electrode containing bacteria, and the two working electrodes are connected in parallel with the counter electrode via an external resistor; The working electrode is made of cobalt / molybdenum disulfide nano-carbon photoelectrocatalyst, used to absorb visible light and generate electrons; under visible light drive, the dual-cathode bioelectrochemical reactor generates hydrogen gas in cathode chamber I and oxidizes wastewater containing organic matter in cathode chamber II; the irradiance of the visible light source is 10-50 mW / cm². 2 In the anode chamber, wastewater containing organic matter is degraded into small molecule organic matter by microorganisms. The method for preparing the cobalt / molybdenum disulfide nano-carbon photocatalyst includes the following steps: The cobalt salt, tetrathiomolybdate, and graphene were dissolved and subjected to a hydrothermal reaction. The product was washed, dried, and then calcined under a reducing atmosphere to obtain the cobalt / molybdenum disulfide nanocarbon photocatalyst.

2. The light-driven dual-cathode bioelectrochemical reactor according to claim 1, characterized in that, The molar ratio of the cobalt salt to tetrathiomolybdate is 1-4:4; the molar ratio of the graphene to tetrathiomolybdate is 5-10:

1.

3. The light-driven dual-cathode bioelectrochemical reactor according to claim 1, characterized in that, The hydrothermal reaction temperature is 150-250℃, and the reaction time is 18-24h.

4. The light-driven dual-cathode bioelectrochemical reactor according to claim 1, characterized in that, The calcination temperature is 600-900℃, and the calcination time is 1-3h.

5. The light-driven dual-cathode bioelectrochemical reactor according to claim 1, characterized in that, The reducing atmosphere is a mixture of hydrogen and an inert gas, wherein the hydrogen volume percentage is 5-15%.

6. The light-driven dual-cathode bioelectrochemical reactor according to claim 1, characterized in that, The cobalt salt includes cobalt nitrate hexahydrate and / or cobalt chloride hexahydrate; the tetrathiomolybdate is ammonium tetrathiomolybdate.

7. The light-driven dual-cathode bioelectrochemical reactor according to claim 1, characterized in that, The resistance value of the external resistor is 10-1000Ω.

8. The light-driven dual-cathode bioelectrochemical reactor according to claim 1, characterized in that, The cathode chamber I and cathode chamber II are each independently equipped with a visible light source.

9. The application of the light-driven dual-cathode bioelectrochemical reactor according to any one of claims 1-8 in the treatment of levofloxacin-containing wastewater, characterized in that, The dual-cathode bioelectrochemical reactor can produce hydrogen gas while treating wastewater.

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