An integrated photoelectrocatalytic degradation system based on a triboelectric nanogenerator

Abstract

The present invention relates to an integrated photoelectric catalytic degradation system based on a friction nanogenerator. The system mainly comprises a plurality of repeated and independently working degradation units, each of which integrates a rolling independent layer friction nanogenerator and a large-area flexible substrate photocatalyst film. The fixed layer of the friction generator is made of tetrafluoroethylene material, and there is a conductive layer on the back. They are fixed on the inner wall of a hollow acrylic cylinder. The mobile layer is made of metal and contacts the fixed layer. The conductive layer is extended to the outer surface of the cylinder and is respectively connected to two flexible photoelectrodes, and the two ends of the cylinder are closed with acrylic sheets. The two ends of the degradation unit are fixed by bearings and half immersed in sewage, and the fins on the surface of the degradation unit are impacted by the flow of the water body, so that the degradation unit is caused to rotate and emit a low-frequency alternating current. The low-frequency alternating current acts on the photoelectrode to perform photoelectric synergistic catalysis on the sewage.

Description

Technical Field

[0001] The present invention relates to the technical fields of environmental protection, water purification, and photo-electro-catalytic technology, and particularly relates to an integrated photo-electro-catalytic degradation system based on a triboelectric nanogenerator and a photocatalyst. Background Art

[0002] The "Water Pollution Investigation Report" of the World Health Organization points out that more than 80% of the diseases and 50% of child deaths globally are related to insufficient drinking water. Among them, organic pollutants such as phenols, polycyclic aromatic hydrocarbons, nitrobenzene, and dyes can invade the human endocrine system, leading to fertility problems, developmental problems, and even cancer. Therefore, the effective treatment of organic pollutants in water has gradually attracted social attention. At present, although photocatalysis has not been widely applied in the industrial field due to cost and efficiency issues, it has considerable application potential due to its low energy consumption, pollution-free nature, universality, and reusability. To solve the problem of low degradation efficiency of a single photocatalyst, researchers usually adopt composite catalytic technologies, and photo-electro-catalytic is a composite degradation technology. This technology uses an electric field to drive the directional movement of photoelectrons on the surface of the photocatalyst to reduce the recombination of hole-electron pairs and increase the generation of hydroxyl radicals; in addition, in the cathode part, due to the movement of charges in water, the rate of generating superoxide radicals will be further accelerated with dissolved oxygen, thereby improving the degradation efficiency of the photocatalyst.

[0003] Chinese Utility Model Application No. 202020731776.1 discloses a pollutant photo-electro-catalytic degradation system, which mainly includes a power supply system, a photocatalytic system, an aeration system, and a stirring system. These four systems are also typical components in current photo-electro-catalytic devices. However, except for the photocatalytic system, the other parts need to be externally powered to work, which increases the energy consumption of photo-electro-catalysis and affects its application value. In 2012, the research team of Professor Zhong Lin Wang invented the triboelectric nanogenerator and proposed the concept of blue energy, which generates electricity by absorbing micro-kinetic energy in nature. In a photo-electro-catalytic device, using a triboelectric nanogenerator as an energy generator to achieve self-driven power generation and replacing the external electric field can minimize the operating cost of the photo-electro-catalytic system. Summary of the Invention

[0004] The purpose of the present invention is to provide a new technology of an integrated photo-electro-catalytic degradation system based on self-power supply of a triboelectric nanogenerator and applicable to low-frequency alternating current, aiming at the problems of the existing photo-electro-catalytic degradation device with complex structure and the need for additional power supply, as well as the difficult application of alternating current in the field of photo-electro-catalysis.

[0005] The technical problems to be solved by the present invention are achieved through the following technical solutions:

[0006] As Figure 1As shown in the figure, the integrated photoelectrocatalytic degradation system based on triboelectric nanogenerator (hereinafter referred to as "system") of the present invention is characterized in that it is composed of multiple repeated and independent degradation units, which can operate in artificial water bodies or natural water bodies. The number of degradation units can be increased or decreased according to the actual working conditions of the system, and most organic pollutants can be fully degraded. Each independent degradation unit is composed of a rolling independent layer triboelectric nanogenerator and two flexible conductive substrate titanium-based titanium dioxide nanowire photocatalyst films (i.e., photoanodes). The two ends of the degradation unit are fixed on the wall of the degradation pool or the underwater bracket through bearings and are semi-immersed in the water body. Small fins are assembled on its surface to collect water flow energy for rotation and power generation. The water flow energy can be artificial or natural. The current generated by the degradation unit is low-frequency alternating current, and its frequency is proportional to the water flow speed. Under the irradiation of xenon lamp light source, the photoanode generates the separation of holes and electrons due to the photoelectric effect, and the low-frequency alternating current can assist the photoanode in the photoelectrocatalytic reaction.

[0007] The degradation unit described above has a component structure as Figure 2 , Figure 3 shown in the figure. The main body of the rolling independent layer triboelectric nanogenerator is a hollow acrylic cylinder with a diameter of Φ50mm, a thickness of 5mm and a length of 100mm. The fixed layer is composed of two polytetrafluoroethylene films with a size of 100mm×50mm×0.1mm, and there is a conductive layer on the back. They are fixed on the inner wall of the acrylic cylinder to form a symmetric arrangement; in order to increase the contact pressure, the moving layer uses an aluminum-clad steel with a diameter of Φ20mm and a length of 95mm, and is placed inside the hollow acrylic cylinder. The conductive layer is extended to the surface of the acrylic cylinder and is respectively connected to two flexible conductive substrates with a size of 8cm×15cm carrying titanium-based titanium dioxide nanowire photocatalyst. The two ends of the acrylic cylinder are closed with acrylic wafers with a diameter of Φ50mm, and the gaps are filled with silicone rubber to achieve sealing. Eight acrylic fins with a size of 10mm×20mm×2mm are vertically fixed on the outer surface of the hollow acrylic cylinder at uniform intervals, so that the degradation unit can rotate with the flow of water, and the rotating triboelectric nanogenerator provides an electric field for the photoanode. Photoelectrochemical catalytic cooperation can be implemented by irradiating the upper surface of the degradation unit with a catalytic light source.

[0008] Optionally, the water body includes but is not limited to artificial circulation pools, and can be natural flowing water channels or rivers.

[0009] Optionally, the main body material includes but is not limited to acrylic, and can also be other plastic insulating materials.

[0010] Optionally, the fixed layer is a thin film with a thickness not exceeding 0.15 mm, including but not limited to polytetrafluoroethylene, and may also be ethylene propylene chloride copolymer, polytetrafluoroethylene, polydimethylsiloxane, polyvinyl chloride, polyimide, polypropylene, polyethylene, polystyrene, polyvinylidene chloride, (poly)acrylonitrile, rubber, or other insulating materials.

[0011] Optionally, the moving layer includes but not limited to aluminum-clad steel, and may also be other metal conductors or nylon, wool, cellulose, animal hair, silk, or paper.

[0012] Optionally, the conductive layer includes but not limited to copper foil, and may also be metals such as gold and silver or graphite, with a thickness not exceeding 0.1 mm.

[0013] Optionally, the photocatalyst includes but not limited to titanium dioxide, and may also be other photocatalytic materials.

[0014] Optionally, the light source for photocatalysis includes but not limited to xenon lamps, and may be ultraviolet lamps, tritium tungsten lamps, bromine tungsten lamps, mercury lamps, sodium lamps, or sunlight or natural light.

[0015] Optionally, the fin material includes but not limited to acrylic, and may also be other hard materials.

[0016] The main body, fixed layer, moving layer, conductive copper foil, and sealing sheet of the degradation unit described in the present invention include, but are not limited to, the above dimensions, and may also be enlarged and reduced in equal proportion.

[0017] The integrated photocatalytic degradation system based on a triboelectric nanogenerator described in the present invention has the following working principle:

[0018] The degradation unit is semi-immersed in the water body containing the target substance to be degraded, and sodium chloride or sodium sulfate is added as an electrolyte. Fins are assembled on the surface of the degradation unit to increase the conductivity of the water body, and their direction is consistent with the direction of water movement. Under the action of water flow, the fins are subjected to a thrust force, causing the degradation unit to rotate. At this time, as the degradation unit rotates, the internal moving friction layer rolls over the fixed friction layer in turn. Due to electrostatic induction and contact electrification, a low-frequency alternating current is generated. The fixed friction layer is connected in series with the two photocathodes on the surface. At this time, the triboelectric generator, photocathodes, and the degraded water body form a closed loop. Among them, the triboelectric generator provides an electric field, and the photocathodes perform catalytic degradation. When the degradation unit is rotating, solution stirring and air injection are carried out simultaneously, and a specific light source is used to irradiate the photocathodes, and then photocatalytic degradation operations can be carried out.

[0019] The integrated photocatalytic degradation system involved in the present invention has the following remarkable features:

[0020] (1) An alternating electric field provided by low-frequency alternating current is used to drive the photocathode to carry out catalytic reactions. The latest research shows (L. Zhou, L. Liu, W. Qiao, Y. Gao, Z. Zhao, D. Liu, Z. Bian, J. Wang and ZLWang, Improving Degradation Efficiency of Organic Pollutants through a Self-Powered Alternating Current Electrocoagulation System [J] ACS Nano, 2021, 15:19684-19691.) that the alternation of the cathode and anode can effectively avoid the oxidation or pollution of the photocathode, and at the same time, the low-frequency alternating current can avoid the generation of thermal effects. In the present invention, the cathode and anode reactions are alternating. On the anode, some of the photoelectrons excited by the photocathode will enter the circuit loop under the electric field, enabling the separated holes to react with H 2 O on the surface of the photocathode to form hydroxyl radicals (·OH). In addition, under aeration, dissolved oxygen will combine with photoelectrons and free electrons to form superoxide radicals (·O 2 - ). At the cathode, a Fenton-like reaction occurs, where dissolved oxygen combines with hydrogen ions and electrons to produce H 2 O 2 , and the generated H 2 O 2 combines with electrons again to form ·OH. These radicals can effectively decompose most organic pollutants.

[0021] (2) The integrated design of the degradation unit allows it to simultaneously complete four process steps: power generation, catalytic degradation, aeration, and stirring during the rotation with the water flow. Compared with the segmented design structure, it has the characteristics of simpler structure, lower manufacturing and usage costs. BRIEF DESCRIPTION OF THE DRAWINGS

[0022] Figure 1 is a working schematic diagram of the integrated photocatalytic degradation system of the present invention.

[0023] Figure 2 is a structural model diagram of the degradation unit.

[0024] Figure 3 is a schematic cross-sectional structure diagram of the degradation unit.

[0025] Figure 4 are the open-circuit voltage output values of the degradation unit under different working conditions (i.e., Example 1, Example 2, Example 3, Example 4, Example 5) of the present invention.

[0026] Figure 5 They are the degradation curves of Embodiment 7, Embodiment 8, and Embodiment 9 of the present invention.

[0027] Figure 6 Scanning electron microscope ×10000 cross-sectional view of titanium-based titanium dioxide nanowires.

[0028] Appendix Figure 2 、 Figure 3 Marking description: 1. Photocatalyst. 2. Conductive copper foil, 3. Teflon film, 4. Acrylic shell, 5. Aluminum-clad steel rod, 6. Fins. Detailed implementation manners

[0029] The present invention will be further described in detail below with reference to the accompanying drawings and specific embodiments, but the protection scope of the present invention is not limited to the following content.

[0030] Embodiment 1

[0031] Assemble a photocatalyst (titanium-based titanium dioxide nanowires), a conductive copper foil, a Teflon film, an acrylic shell, fins, and an aluminum-clad steel rod together in a Figure 2 、 Figure 3 manner to form a degradation unit. Use one degradation unit to form an artificial circulating water system in a Figure 1 manner. The circulating water is sewage containing organic pollutants. By controlling the water flow rate, the rotation speed of the degradation unit is adjusted. When the rotation speed of the degradation unit is 50 rpm, the integrated power supply module can provide an AC output voltage of 14.2 ± 0.2V.

[0032] Embodiment 2

[0033] Assemble a photocatalyst (titanium-based titanium dioxide nanowires), a conductive copper foil, a Teflon film, an acrylic shell, fins, and an aluminum-clad steel rod together in a Figure 2 、 Figure 3 manner to form a degradation unit. Use one degradation unit to form an artificial circulating water system in a Figure 1 manner. The circulating water is sewage containing organic pollutants. By controlling the water flow rate, the rotation speed of the degradation unit is adjusted. When the rotation speed of the degradation unit is 100 rpm, the integrated power supply module can provide an AC output voltage of 15.5 ± 0.9V.

[0034] Embodiment 3

[0035] Assemble a photocatalyst (titanium-based titanium dioxide nanowires), a conductive copper foil, a Teflon film, an acrylic shell, fins, and an aluminum-clad steel rod together in a Figure 2 、 Figure 3 manner to form a degradation unit. Use one degradation unit to form an artificial circulating water system in a Figure 1It is assembled into an artificial circulating water system in the following way. The circulating water is sewage containing organic pollutants. The rotation speed of the degradation unit is adjusted by controlling the water flow rate. When the rotation speed of the degradation unit is 150 rpm, the integrated power supply module can provide an AC output voltage of 21.9 ± 1V.

[0036] Example 4

[0037] The photocatalyst (titanium-based titanium dioxide nanowires), conductive copper foil, polytetrafluoroethylene film, acrylic shell, fins and aluminum-clad steel bars are assembled together in the following Figure 2 , Figure 3 way to form a degradation unit. An artificial circulating water system is built using one degradation unit in the following Figure 1 way. The circulating water is sewage containing organic pollutants. The rotation speed of the degradation unit is adjusted by controlling the water flow rate. When the rotation speed of the degradation unit is 200 rpm, the integrated power supply module can provide an AC output voltage of 18.7 ± 2.6V.

[0038] Example 5

[0039] The photocatalyst (titanium-based titanium dioxide nanowires), conductive copper foil, polytetrafluoroethylene film, acrylic shell, fins and aluminum-clad steel bars are assembled together in the following Figure 2 , Figure 3 way to form a degradation unit. An artificial circulating water system is built using one degradation unit in the following Figure 1 way. The circulating water is sewage containing organic pollutants. The rotation speed of the degradation unit is adjusted by controlling the water flow rate. When the rotation speed of the degradation unit is 300 rpm, the integrated power supply module can provide an AC output voltage of 19.1 ± 1.9V.

[0040] Example 6

[0041] The photocatalyst (titanium-based titanium dioxide nanowires), conductive copper foil, polytetrafluoroethylene film, acrylic shell, fins and aluminum-clad steel bars are assembled together in the following Figure 2 , Figure 3 way to form a degradation unit. An artificial circulating water system is built using one degradation unit in the following Figure 1 way. The circulating water is sewage containing bisphenol A. The rotation speed of the degradation unit is adjusted by controlling the water flow rate, and the unit rotation speed is controlled at 150 rpm. The integrated power supply module can provide an AC output voltage of 21.9 ± 1V. A 300W xenon lamp with an AM 1.5G filter is used to simulate sunlight irradiation of the catalyst to degrade 400 ml of 20 mg / L bisphenol A solution. Sodium sulfate (NaSO 4)Adjust its concentration to 0.05 mol / L to improve the conductivity of the system. After the degradation unit works for 3 hours, the degradation rate of bisphenol A reaches 90.1%; after 6 hours, the degradation rate of bisphenol A reaches 99.5%.

[0042] Example 7

[0043] Assemble the photocatalyst (titanium-based titanium dioxide nanowires), conductive copper foil, polytetrafluoroethylene film, acrylic shell, fins and aluminum-clad steel rods together in a Figure 2 , Figure 3 way to form a degradation unit. Use one degradation unit to build an artificial circulating water system in a Figure 1 way. The circulating water is sewage containing tetracycline. By controlling the water flow rate, the rotation speed of the degradation unit is adjusted, and the unit rotation speed is controlled at 150 rpm. The integrated power supply module can provide an AC output voltage of 21.9 ± 1V. Use a 300W xenon lamp with an AM 1.5G filter to simulate sunlight irradiating the catalyst to degrade 400 ml of 20 mg / L tetracycline solution. Sodium sulfate (NaSO 4 ) is added to the tetracycline solution to make its concentration reach 0.05 mol / L to improve the conductivity of the system. After the degradation unit works for 3 hours, the degradation rate of tetracycline reaches 98.3%; after 6 hours, the degradation rate of tetracycline reaches 98.5%.

[0044] Example 8

[0045] Assemble the photocatalyst (titanium-based titanium dioxide nanowires), conductive copper foil, polytetrafluoroethylene film, acrylic shell, fins and aluminum-clad steel rods together in a Figure 2 , Figure 3 way to form a degradation unit. Use one degradation unit to build an artificial circulating water system (integrated photoelectrocatalytic degradation system) in a Figure 1 way. The circulating water is sewage containing methylene blue. By controlling the water flow rate, the rotation speed of the degradation unit is adjusted, and the unit rotation speed is controlled at 150 rpm. The integrated power supply module can provide an AC output voltage of 21.9 ± 1V. Use a 300W xenon lamp with an AM 1.5G filter to simulate sunlight irradiating the catalyst to degrade 400 ml of 20 mg / L methylene blue solution. Sodium sulfate (NaSO 4 ) is added to the methylene blue solution to make its concentration reach 0.05 mol / L to improve the conductivity of the system. After the degradation unit works for 3 hours, the degradation rate of methylene blue reaches 99.1%; after 6 hours, the degradation rate of methylene blue reaches 99.9%.

[0046] Example 9

[0047] Assemble a photocatalyst (zinc oxide nanorods supported on a stainless steel mesh), a conductive copper foil, a polytetrafluoroethylene film, an acrylic shell, fins, and an aluminum-clad steel rod together according to Figure 2 , Figure 3 to form a degradation unit. Use one degradation unit to assemble an artificial circulating water system (integrated photoelectrocatalytic degradation system) according to Figure 1 . The circulating water is sewage containing methylene blue. Adjust the rotation speed of the degradation unit by controlling the water flow rate, and control the unit rotation speed at 150 rpm. The integrated power supply module can provide an AC output voltage of 21.9 ± 1V. Use a 300W xenon lamp with an AM 1.5G filter to simulate sunlight irradiating the catalyst to degrade 400 ml of 20 mg / L methylene blue solution. Sodium sulfate (NaSO 4 ) is added to the methylene blue solution to make its concentration reach 0.05 mol / L to improve the conductivity of the system. After the degradation unit works for 3 hours, the degradation rate of methylene blue reaches 99.8%; after 6 hours, the degradation rate of methylene blue reaches 100%.

Claims

1. An integrated photoelectrocatalytic degradation system based on a triboelectric nanogenerator, characterized in that: The degradation system is composed of one or more repeated and independent degradation units. Each single degradation unit is of an integrated design and includes: a cylindrical moving friction layer, a fixed friction layer, a conductive layer, a hollow cylindrical sealed housing, a catalytic light source, and a photocatalytic thin film material with a flexible conductive substrate. There is a conductive layer of the same size on the back of the fixed friction layer, and it is fixed on the inner surface of the cylindrical sealed housing with a uniform gap. The moving friction layer is a cylindrical material and contacts the fixed friction layer. Both ends of the hollow cylindrical sealed housing are equipped with bearings and fixed on a bracket or the wall of a container, so that the cylindrical sealed housing is semi-immersed in sewage containing organic pollutants. Fins are installed on the surface of the cylindrical sealed housing to capture water flow energy to drive the sealed housing to rotate, and to prompt the internal moving friction layer to continuously move on the surface of the fixed friction layer to generate a low-frequency alternating electric field. A photocatalytic thin film material with a flexible conductive substrate is fixed on the outer surface of the cylindrical sealed housing, and the flexible conductive substrate of the photocatalytic thin film material is connected to the conductive layer. The degradation system works by irradiating the upper surface of the photoelectrode with a catalytic light source, and simultaneously completes four technological processes of power generation, aeration, stirring, and degradation in the working state.

2. An integrated photoelectrocatalytic degradation system based on a triboelectric nanogenerator according to claim 1, characterized in that, The length of the cylindrical moving friction layer is less than the total inner length of the hollow cylindrical sealed housing, the diameter is less than the inner diameter of the cylindrical sealed housing and greater than 5 mm, and its material is any one of metal conductors, cellulose materials, nylon, animal hair, silk, or paper.

3. An integrated photoelectrocatalytic degradation system based on a triboelectric nanogenerator according to claim 1, characterized in that, The fixed friction layer is a thin film with a thickness not exceeding 0.15 mm, and its material is any one of ethylene propylene chloride copolymer, polytetrafluoroethylene, polydimethylsiloxane, polyvinyl chloride, polyimide, polypropylene, polyethylene, polystyrene, polyvinylidene chloride, acrylonitrile, polyacrylonitrile, or rubber.

4. An integrated photoelectrocatalytic degradation system based on a triboelectric nanogenerator according to claim 1, characterized in that, The conductive layer is a metal or graphite conductive thin film, and its thickness does not exceed 0.1 mm.

5. An integrated photoelectrocatalytic degradation system based on a triboelectric nanogenerator according to claim 1, characterized in that, The material of the hollow cylindrical sealed housing is a plastic insulating material.

6. An integrated photoelectrocatalytic degradation system based on a triboelectric nanogenerator according to claim 1, characterized in that, The catalytic light source is any one of xenon lamps, tritium tungsten lamps, sodium lamps, mercury lamps, or ultraviolet lamps.

7. An integrated photoelectrocatalytic degradation system based on a triboelectric nanogenerator according to claim 1, characterized in that, The photocatalytic thin film material with a flexible conductive substrate is titanium dioxide or zinc oxide.

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