Micro-plastic degradation device based on acousto-optic-thermal synergistic catalysis

Abstract

The invention provides a micro-plastic degradation device based on acousto-optic-thermal synergistic catalysis, which is characterized in that firstly, a water sample to be detected and an activated oxidant are promoted to generate a Fenton-like activated oxidation reaction in a sound wave catalysis mode through a sound module assembly, and meanwhile, the Fenton-like activated oxidation reaction is promoted in a photo-thermal catalysis mode after a photo-thermal catalysis layer is irradiated by light; compared with an existing micro-plastic degradation technology, the micro-plastic degradation device based on acousto-optic-thermal synergistic catalysis can utilize more catalytic reaction modes at the same time, has a synergistic effect, and can realize degradation treatment with lower energy consumption and shorter degradation time in the field of micro-plastic degradation; therefore, the degradation efficiency of the micro-plastics in the water sample to be detected is effectively improved.

Description

Technical Field

[0001] The present invention relates to the technical field of microplastic processing, and in particular to a microplastic degradation device based on acoustic, photothermal and synergistic catalysis. Background Art

[0002] Microplastics are plastic particles with a particle size of less than 5 mm. Due to their difficult decomposition and easy adsorption of pollutants, they have received widespread attention in recent years. Microplastics mainly come from the production, use and disposal of plastic products. They are widely present in water, soil, air and organisms, causing serious harm to the ecological environment and human health. However, existing microplastic degradation technologies generally have technical problems such as incomplete degradation, long degradation time, high energy consumption and pollution, which leads to serious environmental pollution.

[0003] Therefore, designing an efficient and convenient microplastic degradation device has important and urgent practical significance for environmental protection. Summary of the invention

[0004] The purpose of the present invention is to provide a microplastic degradation device based on acoustic, photothermal synergistic catalysis to solve the technical problem of low degradation efficiency of existing microplastic degradation technology.

[0005] In order to solve the above technical problems, the present invention provides a microplastic degradation device based on acoustic, photothermal and synergistic catalysis, comprising a substrate, an acoustic mold component disposed on the substrate, and a polymer layer disposed on the substrate and completely covering the acoustic mold component; At least one reaction chamber is provided between the polymer layer and the substrate, and acoustic mold components are provided on both sides of the reaction chamber. The acoustic mold components are used to generate acoustic field vibrations for the water sample to be tested containing an activated oxidant in the reaction chamber; a photothermal catalytic layer is provided inside the reaction chamber, which is used to thermally degrade the water sample to be tested after being irradiated with light.

[0006] Preferably, the substrate comprises a lithium niobate substrate, the activated oxidant comprises persulfate, and the high molecular polymer layer comprises a polydimethylsiloxane layer.

[0007] Preferably, a groove having microchannels is formed near the bottom surface of the polymer layer on the substrate, and the groove and the substrate are combined to form a reaction chamber; the acoustic mold assembly includes two interdigitated electrodes arranged at intervals, and the groove is located between the two interdigitated electrodes.

[0008] Preferably, each interdigitated electrode comprises a first metal layer disposed on the substrate and a second metal layer disposed on the first metal layer, the material of the first metal layer comprises chromium, and the material of the second metal layer comprises gold; the thickness of the second metal layer is greater than that of the first metal layer.

[0009] Preferably, the thickness of the first metal layer is 30-60 nm, and the thickness of the second metal layer is 100-300 nm.

[0010] Preferably, the total number of electrode fingers of each interdigitated electrode is 30 to 60 pairs, and the line width and line spacing are 80 to 120 μm.

[0011] Preferably, a protective layer is further provided on the upper surface of each interdigital electrode, and the material of the protective layer includes nitride silicon.

[0012] Preferably, the photothermal catalytic layer completely covers the bottom of the reaction chamber, and the photothermal catalytic layer includes one of a transition metal oxide film and a metal organic framework film.

[0013] Preferably, the thickness of the photothermal catalytic layer is 100-300 μm.

[0014] Preferably, an inlet end and an outlet end are respectively provided at two ends of the reaction chamber, the inlet end is communicated with the liquid input channel, and the outlet end is communicated with the liquid output channel.

[0015] The beneficial effect of the present invention is as follows: Different from the prior art, the microplastic degradation device based on acoustic-photothermal synergistic catalysis provided by the present invention first promotes a Fenton-like activation oxidation reaction between the water sample to be tested and the activated oxidant by acoustic wave catalysis through the acoustic mold component, and at the same time promotes the above-mentioned Fenton-like activation oxidation reaction by photothermal catalysis after being irradiated with light through the photothermal catalytic layer. Compared with the existing microplastic degradation technology, the microplastic degradation device based on acoustic-photothermal synergistic catalysis can simultaneously utilize more catalytic reaction modes and have a synergistic effect, and can achieve degradation treatment with lower energy consumption and shorter degradation time in the field of microplastic degradation, thereby effectively improving the degradation efficiency of microplastics in the water sample to be tested. BRIEF DESCRIPTION OF THE DRAWINGS

[0016] Figure 1 A top view of a microplastic degradation device based on acoustic, photothermal synergistic catalysis provided in an embodiment of the present invention; Figure 2 A schematic diagram of the cross-sectional structure of a microplastic degradation device based on acoustic, photothermal synergistic catalysis along the A1A2 direction provided by an embodiment of the present invention; Figure 3 A flow chart of a method for degrading microplastics provided in an embodiment of the present invention; In the figure: 100 - microplastic degradation device; 10 - substrate; 20 - acoustic mold assembly; 21 - interdigitated electrodes; 30 - polymer layer; 31 - reaction chamber; 311 - liquid input channel; 312 - liquid output channel; 40 - photothermal catalytic layer. DETAILED DESCRIPTION

[0017] The following will be combined with the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0018] The purpose of this application is to overcome the above technical deficiencies and propose a microplastic degradation device 100 based on acoustic, photothermal and synergistic catalysis to solve the technical problem of low degradation efficiency of microplastic degradation technology in the prior art due to incomplete degradation and long degradation time.

[0019] See also Figure 1 to Figure 2 , Figure 1 A top view of a microplastic degradation device 100 based on acoustic, photothermal synergistic catalysis provided in an embodiment of the present invention; Figure 2 A schematic diagram of the cross-sectional structure of a microplastic degradation device 100 based on acoustic-photothermal synergistic catalysis provided in an embodiment of the present invention along the direction A1A2; Figure 1 and Figure 2 It can be seen that the above-mentioned microplastic degradation device 100 based on acoustic-photothermal synergistic catalysis includes a substrate 10, an acoustic mold component 20 disposed on the substrate 10, and a polymer layer 30 disposed on the substrate 10 and completely covering the acoustic mold component 20. The polymer layer 30 is provided with a groove having a microchannel near the bottom surface of the substrate 10, and the groove and the substrate 10 are combined to form a reaction chamber 31, and a photothermal catalytic layer 40 is disposed inside the reaction chamber 31; Among them, the reaction chamber 31 is used to load the water sample to be degraded containing microplastics and the activated oxidant, the acoustic model assembly 20 is used to generate acoustic field vibration for the water sample to be tested and promote the Fenton-like activated oxidation reaction between the water sample to be tested and the activated oxidant; the photothermal catalytic layer 40 is used to thermally degrade the water sample to be tested after being irradiated with light and promote the Fenton-like activated oxidation reaction.

[0020] Specifically, the microplastic degradation device 100 based on acoustic, photothermal and synergistic catalysis provided in the present application belongs to a type of microfluidic chip, which is a scientific technology that accurately controls and manipulates fluids at the micrometer scale. Microfluidic chips integrate various functional microchannels, use microchannels (with a size of tens to hundreds of micrometers) to process or manipulate tiny fluids, and create a high-temperature and high-pressure cavity environment that helps catalytic reactions.

[0021] In the embodiment of the present invention, the substrate 10 is the basic supporting part of the entire microplastic degradation device 100, providing a mounting platform for the acoustic mold component 20 and the polymer layer 30, ensuring the relative position stability of each component and the integrity of the overall structure of the device.

[0022] Specifically, the substrate 10 includes a lithium niobate substrate. The lithium niobate substrate used for the substrate 10 has the following advantages: First, lithium niobate (LiNbO3) is a material with excellent acousto-optic properties. The acoustic field vibration generated by the acoustic mode assembly 20 can induce a strong acousto-optic interaction during the propagation of the lithium niobate substrate. This effect can cause the light passing through the lithium niobate substrate to undergo diffraction, refraction and other changes, thereby modulating the propagation direction and intensity of the light. In the microplastic degradation device 100, this characteristic helps to more effectively guide the light to the photothermal catalyst layer 40 and the area where the microplastics are located, enhance the interaction between light and reactants, and improve the photocatalytic efficiency.

[0023] Secondly, the lithium niobate substrate has a moderate sound velocity and low acoustic loss. The moderate sound velocity enables the acoustic field vibration generated by the acoustic mode assembly 20 to propagate in the substrate at a suitable speed and effectively transmit to the water sample in the reaction chamber 31, ensuring that the acoustic energy acts evenly on the entire reaction system. Low acoustic loss ensures the high efficiency of the acoustic energy during the propagation process, reduces energy loss, and enables the acoustic mode assembly 20 to maintain a sufficiently strong acoustic field vibration with low energy consumption, promoting the Fenton-like activation oxidation reaction.

[0024] Thirdly, lithium niobate has a high optical transmittance in a wide wavelength range. This means that the light used to excite the photothermal catalyst layer 40 can smoothly pass through the lithium niobate substrate into the reaction chamber 31, reducing the loss of light during the transmission process of the substrate 10. For example, for common visible light and near-infrared light, the high transmittance of the lithium niobate substrate can ensure that the photothermal catalyst layer 40 fully absorbs light energy, effectively converts light energy into heat energy, improves thermal degradation efficiency and promotes Fenton-like reactions.

[0025] Thirdly, the lithium niobate substrate has good thermal stability and can withstand the high temperature generated by the photothermal catalyst layer 40 after being exposed to light without structural changes or performance degradation. This is crucial to maintaining the stability of the entire microplastic degradation device 100 during long-term operation. For example, under continuous light irradiation, the photothermal catalyst layer 40 may cause the local temperature to rise to tens or even hundreds of degrees Celsius. The thermal stability of the lithium niobate substrate ensures that it can still provide stable support for the acoustic mold assembly 20 and the polymer layer 30 under such temperature conditions, ensuring the normal operation of the device.

[0026] Finally, lithium niobate has good tolerance to many chemical substances and is not easily corroded or chemically reacted in the reaction environment of water samples loaded with microplastics to be degraded and activated oxidants. This chemical stability enables the lithium niobate substrate to work stably for a long time, prolonging the service life of the microplastic degradation device 100, while also avoiding interference with the degradation process due to chemical reactions between the substrate 10 material and the reaction substances.

[0027] In an embodiment of the present invention, the acoustic mold assembly 20 exerts a physical effect on the water sample to be tested in the reaction chamber 31 by generating acoustic field vibrations. This vibration can significantly enhance the movement of molecules in the water sample, allowing the microplastic particles to contact and mix more fully with the activated oxidant. From a microscopic perspective, the intensified molecular thermal motion increases the collision frequency between the reactants, making Fenton-like activated oxidation reactions more likely to occur. For example, in a traditional Fenton-like reaction system, the diffusion rate of the reactants may limit the reaction rate, and the acoustic field vibrations generated by the acoustic mold assembly 20 can effectively break this limitation and improve the reaction efficiency.

[0028] Specifically, the acoustic mold assembly 20 includes two interdigital electrodes 21 disposed at intervals, and the groove is located between the two interdigital electrodes 21 .

[0029] Furthermore, the interdigital electrode 21 is a key component for generating acoustic field vibration. When an alternating voltage is applied to the interdigital electrode 21, due to the inverse piezoelectric effect, the substrate 10 material (such as a lithium niobate substrate) in contact with the interdigital electrode 21 will undergo periodic expansion and contraction deformation. This deformation will excite elastic waves, that is, sound waves, in the material. In the microplastic degradation device 100, these sound waves will be transmitted to the water sample in the reaction chamber 31, thereby generating acoustic field vibration. The two interdigital electrodes 21 are arranged at intervals, and such a layout can form a relatively uniform acoustic field in the area between them. Because the acoustic waves excited by the interdigital electrodes 21 will propagate to the surroundings, the acoustic waves excited by the two spaced electrodes interfere and superimpose with each other, and a relatively stable and uniform acoustic field distribution can be formed in the area between them, so that the water sample to be degraded containing microplastics in the groove (i.e., the reaction chamber 31) can be subjected to a relatively consistent acoustic field effect, ensuring that the Fenton-like activation oxidation reaction is carried out relatively uniformly in the entire reaction area, thereby improving the consistency of the degradation effect.

[0030] Specifically, the total number of electrode fingers of each interdigitated electrode 21 is 30 to 60 pairs, and the line width and line spacing are 80 to 120 μm; wherein, the number of electrode fingers is directly related to the intensity of the excited acoustic energy. More electrode fingers mean that under the same voltage excitation, more piezoelectric material areas will simultaneously undergo expansion and contraction deformation, thereby exciting stronger acoustic energy. In the process of microplastic degradation, stronger acoustic energy can produce more violent acoustic field vibrations, further promoting the mixing and reaction of microplastics and activated oxidants. For example, when the number of electrode fingers increases, the movement of molecules in the water sample becomes more violent, and the collision frequency between microplastic particles and activated oxidants is greatly increased, which accelerates the rate of Fenton-like activated oxidation reactions, which is conducive to more efficient degradation of microplastics. Within the range of 80 to 120 μm line width and line spacing, it can not only ensure a high acoustic energy coupling efficiency, so that sufficient acoustic energy is transmitted to the water sample to induce effective acoustic field vibrations, but also take into account both cost and performance within the achievable range of the actual manufacturing process.

[0031] Specifically, each interdigital electrode 21 includes a first metal layer disposed on the substrate 10 and a second metal layer disposed on the first metal layer, wherein the material of the first metal layer includes chromium, and the material of the second metal layer includes gold; the thickness of the second metal layer is greater than the thickness of the first metal layer. The thickness of the first metal layer is 30-60 nm, and the thickness of the second metal layer is 100-300 nm.

[0032] Furthermore, the first metal layer is made of chromium (Cr), which has good adhesion and can be firmly attached to the surface of the lithium niobate substrate. Due to the surface characteristics of the lithium niobate substrate, directly depositing metals such as gold (Au) on it may result in poor adhesion, and the electrode is easy to fall off during long-term use. The chromium layer, as the bottom layer, provides a reliable adhesion basis for the subsequent metal layer, ensuring the stability of the entire forked electrode 21 structure on the substrate 10, and can maintain a good adhesion state even under the influence of the vibration generated when the acoustic mold assembly 20 is working and the chemical environment in the reaction chamber 31, ensuring the normal operation of the forked electrode 21. The second metal layer is made of gold, which has excellent electrical properties, such as low resistivity, can effectively conduct current, reduce resistance loss under the action of alternating voltage, and improve the efficiency of the forked electrode 21 in exciting the sound field. In addition, gold also has good optical reflection properties to a certain extent. In the microplastic degradation device 100, when light is irradiated, the gold layer can reflect part of the light, change the propagation path of the light near the reaction chamber 31, increase the chance of interaction between the light and the photothermal catalyst layer 40 and the microplastics, and indirectly improve the photocatalytic and thermal degradation effects.

[0033] Furthermore, a relatively thicker gold layer can better exert its electrical and optical advantages. A thicker gold layer can carry a larger current, further reduce resistance loss, and enhance the ability of the interdigital electrodes 21 to excite the acoustic field.

[0034] Specifically, a protective layer is provided on the upper surface of each interdigital electrode 21, and the material of the protective layer includes nitride silicon. Such a design can prevent the interdigital electrodes 21 from being polluted and adsorbed by impurities.

[0035] In the embodiment of the present invention, the polymer layer 30 completely covers the acoustic mold component 20, which protects the acoustic mold component 20 from interference from the external environment and ensures its stable operation; on the other hand, the groove opened near the bottom surface of the substrate 10 forms a reaction chamber 31 together with the substrate 10. The material properties of the polymer layer 30 may play a certain role in protecting the chemical stability of the reaction chamber 31, preventing the water sample and the activated oxidant from causing corrosion and other adverse effects on the internal components.

[0036] Specifically, the polymer layer 30 includes a polydimethylsiloxane layer; the polydimethylsiloxane layer brings many characteristics and advantages to the microplastic degradation device 100 based on acoustic-photothermal synergistic catalysis: First, the polydimethylsiloxane layer has excellent flexibility, which enables the polymer layer 30 to adapt to substrates 10 and internal components of different shapes. In the microplastic degradation device 100, it can fit the substrate 10 and the acoustic mold component 20 tightly. Even when the substrate 10 has a certain degree of unevenness or the acoustic mold component 20 has a complex structure, the polydimethylsiloxane layer can perfectly adapt to it, ensuring the sealing and structural stability of the reaction chamber 31.

[0037] Secondly, the polydimethylsiloxane layer will not interact with reactants such as microplastics and activated oxidants, and will not interfere with the degradation reaction process of microplastics. This allows the reaction to be carried out in a relatively pure environment, which is conducive to accurately evaluating and controlling the degradation effect of microplastics, and avoiding the side reactions between the polymer layer 30 and the reactants that affect the degradation efficiency or produce other unknown chemical reaction products.

[0038] Again, the polydimethylsiloxane layer has a high transmittance in the visible light and near-infrared light regions, which is crucial for the photothermal catalytic process. In the device, light can smoothly pass through the polydimethylsiloxane layer to reach the photothermal catalytic layer 40, ensuring that the photothermal catalytic layer 40 can fully absorb light energy, convert it into heat energy, trigger thermal degradation reactions, and promote Fenton-like activation oxidation reactions. High transmittance reduces the loss of light during transmission and improves the utilization efficiency of light energy, thereby enhancing the degradation effect of microplastics. At the same time, the polydimethylsiloxane layer has good thermal stability and can withstand the high temperatures generated by the photothermal catalytic layer 40 during operation without decomposition, deformation, and other problems.

[0039] Finally, the acoustic impedance of the polydimethylsiloxane layer is close to that of water, which enables the acoustic field vibration generated by the acoustic mold assembly 20 to be effectively transmitted from the substrate 10 to the water sample in the reaction chamber 31. Good acoustic impedance matching reduces the reflection and energy loss of sound waves during transmission, ensuring that the acoustic field vibration of sufficient intensity acts on the water sample, promoting the mixing of microplastics and activated oxidants and Fenton-like activated oxidation reactions, and improving the degradation efficiency of microplastics.

[0040] In the embodiment of the present invention, the reaction chamber 31 is a space where the entire reaction occurs, and it is composed of a groove on the bottom surface of the polymer layer 30 and a substrate 10. Here, the water sample to be degraded with microplastics and the activated oxidant are loaded to provide a place for the subsequent degradation reaction. Among them, the reaction chamber 31 is used to load the water sample to be degraded with microplastics and the activated oxidant, and the activated oxidant includes persulfate.

[0041] Specifically, persulfates (such as potassium persulfate, sodium persulfate, etc.) can generate sulfate radicals (SO4 2⁻), which has extremely strong oxidizing ability, and even performs better than hydroxyl radicals in some cases. These strong oxidizing free radicals can quickly attack the chemical bonds on the surface of microplastics, oxidizing and decomposing them into small molecules, thereby achieving the degradation of microplastics. For example, for some high-molecular-weight microplastics that are difficult to degrade, sulfate radicals can destroy their carbon-carbon bonds, carbon-hydrogen bonds, etc., and gradually decompose them into low-molecular-weight compounds.

[0042] In an embodiment of the present invention, the photothermal catalytic layer 40 completely covers the bottom of the reaction chamber 31 and is one of the key functional layers for achieving microplastic degradation. When irradiated with light, the photothermal catalytic layer 40 can convert light energy into thermal energy to thermally degrade the water sample to be tested. At the same time, this photothermal effect can further promote Fenton-like activation oxidation reactions. From the perspective of chemical reaction kinetics, an increase in temperature will increase the activation energy of the reactant molecules, enabling more molecules to react, thereby accelerating the reaction rate. Moreover, the photothermal catalytic layer 40 may also have catalytic active sites that can selectively promote the key steps in Fenton-like reactions and improve the efficiency and selectivity of the reaction.

[0043] Specifically, the photothermal catalyst layer 40 includes one of a transition metal oxide film and a metal organic framework film, and the thickness of the photothermal catalyst layer 40 is 100~300μm. Among them, a thinner thickness (such as 100μm) can enable light to penetrate the film more effectively, increase the action area of ​​light and transition metal oxide, improve the utilization efficiency of light, and facilitate the generation of photogenerated carriers. However, too thin may result in insufficient heat generated by photothermal conversion and a limited number of catalytic active sites. A thicker thickness (such as 300μm) can provide more catalytic active sites, enhance the activation ability of persulfate, and accumulate more heat for thermal degradation. However, excessive thickness will increase the absorption loss of light, resulting in the inability of light to effectively reach the internal area, reducing the overall photothermal catalytic efficiency. Therefore, this thickness range seeks a balance between light absorption, heat accumulation, and catalytic activity.

[0044] In the embodiment of the present invention, the two ends of the reaction chamber 31 are respectively provided with an inlet and an outlet, the inlet is connected to the liquid input channel 311, and the outlet is connected to the liquid output channel 312. This design can realize the continuous input and output of the water sample to be tested and maintain the stability of the reaction system.

[0045] See also Figure 3 , Figure 3 A flow chart of a microplastic degradation method provided in an embodiment of the present invention; wherein the above-mentioned degradation method specifically comprises the following steps: S1, applying a radio frequency electric field to the acoustic mode assembly 20 to generate surface acoustic waves; S2, irradiating visible light to excite the photothermal catalyst layer 40; S3, injecting a mixed water sample formed by the microplastic water sample and the activated oxidant from the inlet end of the reaction chamber 31, and uniformly mixing them in the microchannel of the reaction chamber 31; S4, generating an acoustic field through the acoustic model assembly 20 to vibrate the water sample to be tested to promote Fenton-like activation oxidation, and at the same time generating heat through the photothermal catalytic layer 40 to perform thermal digestion and promote Fenton-like activation oxidation.

[0046] Specifically, due to the effect of the acoustic field of the mold assembly, the surface of the photothermal catalytic layer 40 undergoes mechanical deformation, thereby making it easier for the microplastics (microspheres) in the water sample to be tested to be adsorbed on the photothermal catalytic layer 40 .

[0047] The technical solution of the present invention is now described in conjunction with specific embodiments.

[0048] Embodiment 1: See also Figure 1 as well as Figure 2 , this embodiment 1 provides a microplastic degradation device 100 based on acoustic-photothermal synergistic catalysis, comprising a substrate 10, an acoustic mold component 20 disposed on the substrate 10, and a polymer layer 30 disposed on the substrate 10 and completely covering the acoustic mold component 20, wherein the polymer layer 30 has a groove with a microchannel near the bottom surface of the substrate 10, and the groove and the substrate 10 are combined to form a reaction chamber 31, and a photothermal catalytic layer 40 is disposed inside the reaction chamber 31; Among them, the reaction chamber 31 is used to load the water sample to be degraded containing microplastics and the activated oxidant, the acoustic model assembly 20 is used to generate acoustic field vibration for the water sample to be tested and promote the Fenton-like activated oxidation reaction between the water sample to be tested and the activated oxidant; the photothermal catalytic layer 40 is used to thermally degrade the water sample to be tested after being irradiated with light and promote the Fenton-like activated oxidation reaction.

[0049] The specific parameters of each film layer in this embodiment 1 are as follows: The substrate 10 is a lithium niobate substrate, the length and width of the lithium niobate substrate are 10 cm and 5 cm respectively; The acoustic mold assembly 20 includes two interdigitated electrodes 21, and the groove is located between the two interdigitated electrodes 21; each interdigitated electrode 21 includes a first metal layer disposed on the substrate 10 and a second metal layer disposed on the first metal layer; the material of the first metal layer is chromium, and the thickness is 50nm; the material of the second metal layer includes gold, and the thickness is 200nm. The interdigitated electrode 21 is a comb-shaped electrode, and the total number of electrode fingers is 50 pairs, and the line width and line spacing are 100μm; The polymer layer 30 is made of polydimethylsiloxane; The reaction chamber 31 consists of a microchannel for inputting and outputting mixed water samples and a rectangular cavity; the length, width and height of the reaction chamber 31 are 20 mm, 15 mm and 50 μm respectively, and the total volume is 150 μL; the inlet end of the reaction chamber 31 is used to input a mixed solution of microplastic water samples and persulfate solution to form a Fenton-like reaction system, and the outlet end is connected to the outlet of the microchannel to discharge the degraded water sample; the height of the microchannel in the reaction chamber 31 is 50 μm, which is closely combined with other membrane layers; The photothermal catalytic layer 40 is made of titanium dioxide with a thickness of 200 nm. It completely covers the bottom of the reaction chamber 31 and can form a Fenton-like reaction system with the persulfate in the mixed water sample to oxidize and degrade the mixed water sample. It can generate heat through the photothermal conversion mechanism to stimulate photocatalysis and photothermal catalytic digestion. When the acoustic field is applied, the photothermal catalytic material will undergo dynamic deformation, promoting the acoustic catalytic effect.

[0050] Specifically, the preparation method of the microplastic degradation device 100 based on acoustic, photothermal and synergistic catalysis provided in this embodiment 1 is as follows: (1) Preparation of flow cell mold: A chip designed according to the reaction chamber is made into a mask template, and SU8-50 negative photoresist is applied to the surface for uniform coating; then baking, exposure, and re-baking are performed. After completion, the photoresist outside the microstructure is removed and the film is hardened to make the structure more solid, thereby obtaining a flow cell mold with a microstructure. The microstructure is a groove with a microchannel, and the height of the microchannel is 50 μm.

[0051] (2) Preparation of polymer layer 30: polydimethylsiloxane and curing agent are mixed in proportion and stirred thoroughly until uniform small bubbles are present in the mixture to obtain a polymer. Then, a certain amount of the uniformly mixed polymer is poured onto the prepared silicon wafer template (the flow cell mold is placed on the corresponding position of the silicon wafer template before pouring), and the mixture is placed in an oven for heating and vacuuming. Finally, the polymer layer 30 with grooves after curing is removed, and holes are punched at the inlet and outlet of the microchannel. (3) Preparation of acoustic mold component 20: Provide a lithium niobate substrate and clean its surface. Then, place the lithium niobate substrate in an electron beam evaporation coating machine. After evacuation, first evaporate a 50nm chromium metal layer and then evaporate a 200nm gold layer. Use a coating machine to spin-coat a uniform layer of photoresist on the surface of the glass substrate with a thickness of about 1~2μm. Use a photolithography machine and a photolithography plate with a prepared interdigital electrode 21 pattern to perform an ultraviolet exposure process on the surface of the glass sheet. Develop in a developer to obtain a mask pattern. After photolithography is completed, an electrode pattern of the photoresist is formed on the surface of the chromium-gold metal film. Finally, two oppositely arranged interdigital electrodes 21 are obtained on the surface of the lithium niobate substrate to form an acoustic mold component 20. The acoustic mold component 20 is simultaneously connected to an external RF signal generator, a signal amplifier, and a power supply to promote the generation of surface acoustic waves.

[0052] (4) Preparation of the photothermal catalyst layer 40: A photothermal catalyst layer 40 made of titanium dioxide is in situ grown in the region corresponding to the two interdigitated electrodes 21 on the lithium niobate substrate; the thickness of the photothermal catalyst layer 40 is 200 nm, and its size is the same as the opening size of the groove in the polymer layer 30; (5) Preparation of the microplastic degradation device 100: The polymer layer 30 and the lithium niobate substrate are placed in a plasma cleaning machine for cleaning. After cleaning, the side of the polymer layer 30 with the groove is bonded to the lithium niobate substrate by ion bombardment to obtain a microplastic degradation device 100 with a reaction chamber 31, wherein the photothermal catalytic layer 40 is located in the reaction chamber 31 and completely covers the bottom surface of the reaction chamber 31. This tightly combined method can avoid the generation of bubbles, thereby avoiding interference with the experiment and accurate measurement.

[0053] Specifically, the microplastic degradation method provided in this embodiment 1 specifically includes the following steps: (1) applying a radio frequency electric field to the acoustic mode assembly 20 to generate surface acoustic waves; (2) irradiating visible light to excite the photothermal catalyst layer 40; white light is irradiated on the surface of the photothermal catalyst layer 40 to excite electrons and holes, which can promote the photocatalytic reaction to degrade microplastics; (3) injecting the mixed liquid of microplastics and persulfate into the liquid input channel 311 from the inlet end and uniformly mixing them in the microchannel; (4) The mixed liquid enters the reaction chamber 31, and the Fenton-like oxidation system, microfluidic reaction system, and acoustic-photothermal degradation system are carried out simultaneously; during the reaction process, the surface acoustic wave causes the substrate 10 to produce mechanical deformation, and the deformation has a different electrode sequence from the material of the photothermal catalyst layer 40, and an electric field is generated on the photothermal catalyst layer 40, so that the electrons and holes generated by light in the photothermal catalyst layer 40 move in different directions of electric potential, respectively, which can enhance the photothermal catalytic efficiency. The photothermal catalyst layer 40 absorbs the incident light through the photothermal material and converts the light energy into heat energy. This conversion process can achieve complete degradation through local heating of plasma, non-radiative relaxation of semiconductors, or thermal vibration of molecules; (5) After the degradation is completed, the mixed water sample flows out from the output port through the liquid output channel 312.

[0054] In this embodiment, the lithium niobate substrate 10 area directly below the reaction chamber 31 is covered with a photothermal catalytic material film, which has the same plane size as the reaction chamber 31, and is used to perform photothermal-Fenton-like synergistic degradation of microplastic water samples. Under the reaction chamber 31, the photothermal catalytic material film uses the water pressure in the reaction chamber 31 to form a high-temperature and high-pressure environment, which promotes the occurrence of a Fenton-like system.

[0055] The embodiment of the present application designs a microplastic degradation device 100 based on acoustic-photothermal synergistic catalysis, which produces a combination of a microfluidic degradation chip and a variety of enhancement effects, forming a new method for rapid and complete degradation of microplastic water samples. It combines a microfluidic chip with a variety of enhancement effects, and uses photocatalysis, acoustic-photocatalysis, and photothermal catalysis to degrade microplastics simultaneously or separately. The microplastic degradation device 100 has a small size and low energy consumption, and can improve the degradation efficiency of microplastics. The embodiment of the present application is based on Fenton-like oxidation technology, photothermal conversion technology, acoustic-photodegradation technology, and microfluidic technology, which can solve the problem of the difficulty of degrading existing microplastic water samples.

[0056] In summary, different from some existing technologies, the embodiment of the present application designs a microplastic degradation device 100 based on acoustic, photothermal synergistic catalysis, which produces a combination of a microfluidic chip and multiple enhancement effects, forming a new method for rapid and complete degradation of microplastic water samples. It uses photocatalysis, acoustic, photocatalysis, and photothermal catalysis to degrade microplastics simultaneously or separately. Compared with the existing microplastic degradation technology, the microplastic degradation device 100 can simultaneously utilize more catalytic reaction modes and have synergistic effects, and can achieve rapid processing with less energy consumption in the field of microplastic degradation, and can shorten the degradation time to within a few minutes.

[0057] The above embodiments only express the implementation methods of the present invention, and the descriptions thereof are relatively specific and detailed, but they cannot be understood as limiting the scope of the invention patent. It should be pointed out that, for those of ordinary skill in the art, several variations and improvements can be made without departing from the concept of the present invention, and these all belong to the protection scope of the present invention. Therefore, the protection scope of the patent of the present invention shall be subject to the attached claims.

Claims

1. A microplastic degradation device based on acoustic, photothermal and synergistic catalysis, characterized in that: It comprises a substrate, an acoustic mold component disposed on the substrate, and a polymer layer disposed on the substrate and completely covering the acoustic mold component; At least one reaction chamber is provided between the polymer layer and the substrate, and the acoustic mold components are provided on both sides of the reaction chamber, and the acoustic mold components are used to generate acoustic field vibrations for the water sample to be tested containing the activated oxidant in the reaction chamber; A photothermal catalytic layer is arranged inside the reaction chamber, which is used to thermally degrade the water sample to be tested after being irradiated with light.

2. The microplastic degradation device based on acoustic, photothermal and synergistic catalysis according to claim 1 is characterized in that: The substrate comprises a lithium niobate substrate, the activated oxidant comprises persulfate, and the high molecular polymer layer comprises a polydimethylsiloxane layer.

3. The microplastic degradation device based on acoustic, photothermal and synergistic catalysis according to claim 1 is characterized in that: The polymer layer is provided with a groove having a microchannel near the bottom surface of the substrate, and the groove is combined with the substrate to form the reaction chamber; the acoustic mold component includes two interdigitated electrodes arranged at intervals, and the groove is located between the two interdigitated electrodes.

4. The microplastic degradation device based on acoustic, photothermal and synergistic catalysis according to claim 3 is characterized in that: Each of the interdigitated electrodes includes a first metal layer disposed on the substrate and a second metal layer disposed on the first metal layer. The material of the first metal layer includes chromium, and the material of the second metal layer includes gold. The thickness of the second metal layer is greater than that of the first metal layer.

5. The microplastic degradation device based on acoustic, photothermal and synergistic catalysis according to claim 4 is characterized in that: The thickness of the first metal layer is 30-60 nm, and the thickness of the second metal layer is 100-300 nm.

6. The microplastic degradation device based on acoustic, photothermal and synergistic catalysis according to claim 3 is characterized in that: The total number of electrode fingers of each interdigitated electrode is 30 to 60 pairs, and the line width and line spacing are 80 to 120 μm.

7. The microplastic degradation device based on acoustic, photothermal and synergistic catalysis according to claim 3 is characterized in that: A protective layer is also provided on the upper surface of each of the interdigital electrodes, and the material of the protective layer includes nitride silicon.

8. The microplastic degradation device based on acoustic, photothermal synergistic catalysis according to claim 1 is characterized in that: The photothermal catalytic layer completely covers the bottom of the reaction chamber, and the photothermal catalytic layer includes one of a transition metal oxide film and a metal organic framework film.

9. The microplastic degradation device based on acoustic, photothermal and synergistic catalysis according to claim 8 is characterized in that: The thickness of the photothermal catalytic layer is 100-300 μm.

10. The microplastic degradation device based on acoustic, photothermal synergistic catalysis according to claim 1 is characterized in that: An inlet end and an outlet end are respectively arranged at two ends of the reaction chamber, the inlet end is communicated with a liquid input channel, and the outlet end is communicated with a liquid output channel.

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