A microplastic degradation device based on acoustic, photothermal synergistic catalysis

Abstract

The present invention provides a microplastic degradation device based on acoustic-photothermal synergistic catalysis, which first promotes a Fenton-like activation oxidation reaction between a water sample to be tested and an activated oxidant by acoustic wave catalysis through an acoustic mold component, and simultaneously promotes the above-mentioned Fenton-like activation oxidation reaction by photothermal catalysis after being irradiated with light through a 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.

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 synergistic catalysis. Background Art

[0002] Microplastics, defined as plastic particles smaller than 5 mm in size, have garnered widespread attention in recent years due to their resistance to degradation and their propensity to absorb pollutants. Microplastics primarily originate from the production, use, and disposal of plastic products. They are widely present in water, soil, air, and organisms, posing a serious threat to the ecological environment and human health. However, existing microplastic degradation technologies suffer from incomplete degradation, prolonged degradation times, and high energy consumption and pollution, resulting in significant 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] 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;

[0006] 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 the 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.

[0007] Preferably, the substrate comprises a lithium niobate substrate, the activated oxidant comprises persulfate, and the high molecular polymer layer comprises a polydimethylsiloxane layer.

[0008] Preferably, the polymer layer is provided with a groove having microchannels near the bottom surface of the substrate, and the groove and the substrate are combined to form a reaction chamber; the acoustic mold assembly includes two interdigital electrodes arranged at intervals, and the groove is located between the two interdigital electrodes.

[0009] Preferably, each interdigitated electrode 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 the thickness of the first metal layer.

[0010] Preferably, the thickness of the first metal layer is 30-60 nm, and the thickness of the second metal layer is 100-300 nm.

[0011] 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.

[0012] 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.

[0013] 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.

[0014] Preferably, the thickness of the photothermal catalytic layer is 100-300 μm.

[0015] Preferably, an inlet and an outlet are respectively provided at both ends of the reaction chamber, the inlet is communicated with the liquid input channel, and the outlet is communicated with the liquid output channel.

[0016] The beneficial effects of the present invention are: different from the existing technology, the microplastic degradation device based on acoustic, photothermal and synergistic catalysis provided by the present invention first promotes the 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 and 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

[0017] Figure 1 A top view of a microplastic degradation device based on acoustic, photothermal synergistic catalysis provided by an embodiment of the present invention;

[0018] 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;

[0019] Figure 3 A flow chart of the microplastic degradation method provided in an embodiment of the present invention;

[0020] In the figure: 100 - microplastic degradation device; 10 - substrate; 20 - acoustic mode assembly; 21 - interdigitated electrodes; 30 - polymer layer; 31 - reaction chamber; 311 - liquid input channel; 312 - liquid output channel; 40 - photothermal catalytic layer. DETAILED DESCRIPTION

[0021] 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 embodiments described 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 making creative efforts are within the scope of protection of the present invention.

[0022] The purpose of this application is to overcome the above technical deficiencies and propose a microplastic degradation device 100 based on acoustic, photothermal 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.

[0023] See also Figures 1 to 2 , Figure 1 A top view of a microplastic degradation device 100 based on acoustic, photothermal synergistic catalysis provided by an embodiment of the present invention; Figure 2 A schematic diagram of the cross-sectional structure of the microplastic degradation device 100 based on acoustic, photothermal synergistic catalysis provided by an embodiment of the present invention along the A1A2 direction; Figure 1 and Figure 2 It can be seen that the above-mentioned microplastic degradation device 100 based on acoustic, photothermal and 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 has a groove with a microchannel near the bottom surface of the substrate 10. The groove and the substrate 10 are combined to form a reaction chamber 31. The photothermal catalytic layer 40 is disposed inside the reaction chamber 31;

[0024] 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 activation 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 activation oxidation reaction.

[0025] Specifically, the microplastic degradation device 100 based on acoustic, photothermal, and synergistic catalysis provided herein belongs to a class of microfluidic chips. Microfluidic chips are a scientific technology that precisely controls and manipulates fluids at the micrometer scale. Microfluidic chips integrate various functional microchannels. These use microchannels (tens to hundreds of micrometers in size) to process or manipulate tiny fluids, creating a high-temperature, high-pressure cavity environment that facilitates catalytic reactions.

[0026] 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.

[0027] Specifically, the substrate 10 includes a lithium niobate substrate. The use of a lithium niobate substrate for the substrate 10 has the following advantages:

[0028] First, lithium niobate (LiNbO3) is a material with excellent acousto-optic properties. The acoustic field vibrations generated by the acoustic mode assembly 20 can trigger a strong acousto-optic interaction as they propagate through the lithium niobate substrate. This interaction causes light passing through the lithium niobate substrate to undergo diffraction and refraction, thereby modulating the direction and intensity of light propagation. In the microplastic degradation device 100, this property helps to more effectively direct light to the photothermal catalyst layer 40 and the area where the microplastics are located, enhancing the interaction between light and reactants and improving photocatalytic efficiency.

[0029] Secondly, the lithium niobate substrate has a moderate acoustic velocity and low acoustic loss. This moderate acoustic velocity enables the acoustic field vibrations generated by the acoustic mode assembly 20 to propagate through the substrate at an appropriate speed and be effectively transferred to the water sample in the reaction chamber 31, ensuring that the acoustic energy is uniformly applied throughout the reaction system. Low acoustic loss ensures efficient propagation of acoustic energy, minimizing energy loss. This allows the acoustic mode assembly 20 to maintain sufficiently high acoustic field vibrations with low energy consumption, promoting the Fenton-like activation oxidation reaction.

[0030] Thirdly, lithium niobate has high optical transmittance over 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 and enter the reaction chamber 31, reducing light loss during transmission through the substrate 10. For example, for common visible and near-infrared light, the high transmittance of the lithium niobate substrate ensures that the photothermal catalyst layer 40 fully absorbs the light energy, effectively converting it into heat energy, improving thermal degradation efficiency and promoting Fenton-like reactions.

[0031] Thirdly, the lithium niobate substrate exhibits excellent thermal stability, capable of withstanding the high temperatures generated by the photothermal catalyst layer 40 upon exposure to light without undergoing structural changes or performance degradation. This is crucial for maintaining the stability of the entire microplastic degradation device 100 during prolonged operation. For example, under continuous light exposure, the photothermal catalyst layer 40 may locally increase its temperature to tens or even hundreds of degrees Celsius. The thermal stability of the lithium niobate substrate ensures that it can provide stable support for the acoustic mold assembly 20 and polymer layer 30 under such temperature conditions, ensuring the proper functioning of the device.

[0032] Finally, lithium niobate exhibits excellent tolerance to many chemical substances. It is not susceptible to corrosion or chemical reactions in the reaction environment of the water sample containing microplastics to be degraded and the activated oxidant. This chemical stability enables the lithium niobate substrate to operate stably and long-term, extending the lifespan of the microplastic degradation device 100. It also prevents chemical reactions between the substrate 10 material and the reactants from interfering with the degradation process.

[0033] 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 microplastic particles to more fully contact and mix with the activated oxidant. From a microscopic perspective, the intensified molecular thermal motion increases the frequency of collisions between reactants, making Fenton-like activation 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, but the acoustic field vibrations generated by the acoustic mold assembly 20 can effectively break this limitation and improve the reaction efficiency.

[0034] Specifically, the acoustic mold assembly 20 includes two interdigital electrodes 21 spaced apart from each other, and the groove is located between the two interdigital electrodes 21 .

[0035] Furthermore, the interdigitated electrodes 21 are key components for generating acoustic field vibrations. When an alternating voltage is applied to the interdigitated electrodes 21, the substrate 10 material (e.g., a lithium niobate substrate) in contact with the interdigitated electrodes 21 undergoes periodic expansion and contraction deformation due to the inverse piezoelectric effect. This deformation excites elastic waves, or acoustic waves, in the material. In the microplastic degradation device 100, these acoustic waves are transmitted into the water sample in the reaction chamber 31, generating acoustic field vibrations. The two interdigitated electrodes 21 are spaced apart, creating a relatively uniform acoustic field in the area between them. Because the acoustic waves excited by the interdigitated electrodes 21 propagate outward, the acoustic waves excited by the two spaced electrodes interfere and superimpose, forming a relatively stable and uniform acoustic field distribution in the area between them. This ensures that the water sample containing microplastics to be degraded within the groove (i.e., the reaction chamber 31) is subjected to a relatively consistent acoustic field, ensuring that the Fenton-like activation oxidation reaction proceeds relatively evenly throughout the reaction area, improving the consistency of the degradation effect.

[0036] Specifically, each interdigitated electrode 21 has 30 to 60 pairs of electrode fingers, with a line width and line spacing of 80 to 120 μm. The number of electrode fingers directly affects the intensity of the excited acoustic energy. More electrode fingers mean that under the same voltage excitation, more areas of the piezoelectric material will simultaneously expand and contract, thereby stimulating stronger acoustic energy. During the microplastic degradation process, stronger acoustic energy can generate more intense acoustic field vibrations, further promoting the mixing and reaction of microplastics with the activated oxidant. For example, when the number of electrode fingers increases, the movement of molecules in the water sample becomes more intense, significantly increasing the frequency of collisions between microplastic particles and the activated oxidant, accelerating the rate of the Fenton-like activation oxidation reaction and promoting more efficient microplastic degradation. Within the line width and line spacing range of 80 to 120 μm, high acoustic energy coupling efficiency is ensured, allowing sufficient acoustic energy to be transmitted to the water sample to induce effective acoustic field vibrations, while also balancing cost and performance within the achievable range of practical manufacturing processes.

[0037] 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. The first metal layer is made of chromium, and the second metal layer is made of gold. The second metal layer is thicker than the first metal layer. The first metal layer has a thickness of 30 to 60 nm, and the second metal layer has a thickness of 100 to 300 nm.

[0038] Furthermore, the first metal layer is made of chromium (Cr), which has excellent adhesion and firmly adheres to the surface of the lithium niobate substrate. Due to the surface properties of the lithium niobate substrate, directly depositing metals such as gold (Au) on it may result in poor adhesion, making the electrodes susceptible to detachment during long-term use. The chromium layer, as a base layer, provides a reliable adhesion foundation for subsequent metal layers, ensuring the stability of the entire interdigital electrode 21 structure on the substrate 10. This ensures good adhesion even under the influence of vibrations generated by the acoustic mold assembly 20 and the chemical environment in the reaction chamber 31, ensuring the proper function of the interdigital electrodes 21. The second metal layer is made of gold, which has excellent electrical properties, such as low resistivity. Gold effectively conducts current, reduces resistance losses under alternating voltage, and improves the efficiency of the interdigital electrodes 21 in exciting the acoustic field. Furthermore, gold also has good optical reflectivity 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 opportunity for light to interact with the photothermal catalyst layer 40 and microplastics, and indirectly improve the photocatalytic and thermal degradation effects.

[0039] Furthermore, a relatively thicker gold layer can better demonstrate 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.

[0040] 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. This design can prevent the interdigital electrodes 21 from being contaminated and adsorbed by impurities.

[0041] In this embodiment of the present invention, polymer layer 30 completely covers acoustic mold assembly 20. This not only protects acoustic mold assembly 20 from external interference, ensuring stable operation, but also forms a reaction chamber 31 with the substrate 10 through a recessed surface near the bottom surface of the substrate 10. The material properties of polymer layer 30 may provide a certain degree of chemical stability for reaction chamber 31, preventing corrosion and other adverse effects of the aqueous sample and activated oxidant on internal components.

[0042] 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:

[0043] First, the polydimethylsiloxane layer possesses exceptional flexibility, allowing the polymer layer 30 to adapt to the varying shapes of the substrate 10 and internal components. In the microplastic degradation device 100, it can closely adhere to the substrate 10 and acoustic mold assembly 20. Even when the substrate 10 has some unevenness or the acoustic mold assembly 20 has a complex structure, the polydimethylsiloxane layer perfectly adapts to these, ensuring the sealing and structural stability of the reaction chamber 31.

[0044] Secondly, the polydimethylsiloxane layer does not interact with reactants such as microplastics and activated oxidants, and does not interfere with the microplastic degradation reaction process. This allows the reaction to proceed in a relatively pure environment, facilitating accurate assessment and control of microplastic degradation, and avoiding side reactions between the polymer layer 30 and the reactants that could affect degradation efficiency or produce other unknown chemical reaction products.

[0045] 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 and trigger thermal degradation reactions and promote Fenton-like activation oxidation reactions. High transmittance reduces the loss of light during transmission, improves the utilization efficiency of light energy, and thus enhances 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 problems such as decomposition and deformation.

[0046] Finally, the acoustic impedance of the polydimethylsiloxane layer is close to that of water, which enables the acoustic field vibrations 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 reflection and energy loss during the transmission process of sound waves, ensuring that the acoustic field vibrations of sufficient intensity act on the water sample, promoting the mixing of microplastics and the activated oxidant and the Fenton-like activation oxidation reaction, thereby improving the degradation efficiency of microplastics.

[0047] In this embodiment of the present invention, reaction chamber 31 serves as the space where the entire reaction occurs. It is formed by the groove on the bottom surface of polymer layer 30 and substrate 10. Here, the water sample containing microplastics to be degraded and the activated oxidant are loaded, providing a venue for the subsequent degradation reaction. Specifically, reaction chamber 31 is used to load the water sample containing microplastics to be degraded and the activated oxidant, which includes persulfate.

[0048] Specifically, persulfates (such as potassium persulfate, sodium persulfate, etc.) can generate sulfate radicals (SO4 2⁻) have extremely strong oxidizing power, even outperforming hydroxyl radicals in some cases. These strong oxidizing radicals can rapidly attack the chemical bonds on the surface of microplastics, oxidizing them into small molecules and thus degrading them. For example, sulfate radicals can break down carbon-carbon and carbon-hydrogen bonds in some difficult-to-degrade high-molecular-weight microplastics, gradually breaking them down into low-molecular-weight compounds.

[0049] 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 heat 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 have the ability to react, thereby accelerating the reaction rate. Moreover, the photothermal catalytic layer 40 may also have catalytic active sites, which can selectively promote the key steps in the Fenton-like reaction and improve the efficiency and selectivity of the reaction.

[0050] Specifically, the photothermal catalyst layer 40 comprises a transition metal oxide thin film or a metal-organic framework thin film, and has a thickness of 100 to 300 μm. A thinner thickness (e.g., 100 μm) allows light to penetrate the thin film more efficiently, increasing the area of ​​interaction between light and the transition metal oxide, improving light utilization efficiency, and facilitating the generation of photogenerated carriers. However, excessively thin thicknesses may result in insufficient heat generated by photothermal conversion and a limited number of catalytically active sites. A thicker thickness (e.g., 300 μm) can provide more catalytically active sites, enhancing persulfate activation while accumulating more heat for thermal degradation. However, excessive thickness increases light absorption loss, preventing light from effectively reaching the inner region and reducing the overall photothermal catalytic efficiency. Therefore, this thickness range strikes a balance between light absorption, heat accumulation, and catalytic activity.

[0051] In the embodiment of the present invention, the reaction chamber 31 is provided with an inlet and an outlet at both ends, the inlet communicating with the liquid input channel 311, and the outlet communicating with the liquid output channel 312. This design allows for continuous input and output of the water sample to be tested, while maintaining the stability of the reaction system.

[0052] 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 includes the following steps:

[0053] S1, applying a radio frequency electric field to the acoustic module 20 to generate surface acoustic waves;

[0054] S2, irradiating visible light to excite the photothermal catalyst layer 40;

[0055] 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;

[0056] S4, generating an acoustic field through the acoustic mode assembly 20 to vibrate the water sample to be tested to promote Fenton-like activation oxidation, while generating heat through the photothermal catalytic layer 40 to perform thermal decomposition and promote Fenton-like activation oxidation.

[0057] 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 the microplastics (microspheres) in the water sample to be tested more easily adsorbed on the photothermal catalytic layer 40 .

[0058] The technical solution of the present invention will now be described with reference to specific embodiments.

[0059] Example 1:

[0060] See also Figure 1 as well as Figure 2 This embodiment 1 provides a microplastic degradation device 100 based on acoustic, photothermal and synergistic catalysis, comprising a substrate 10, an acoustic mold assembly 20 disposed on the substrate 10, and a polymer layer 30 disposed on the substrate 10 and completely covering the acoustic mold assembly 20. The polymer layer 30 has a groove having a microchannel formed near the bottom surface of the substrate 10. The groove and the substrate 10 are combined to form a reaction chamber 31. The reaction chamber 31 has a photothermal catalytic layer 40 disposed therein.

[0061] 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 activation 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 activation oxidation reaction.

[0062] The specific parameters of each film layer in this embodiment 1 are as follows:

[0063] The substrate 10 is a lithium niobate substrate, the length and width of the lithium niobate substrate are 10 cm and 5 cm respectively;

[0064] The acoustic mold assembly 20 includes two interdigital electrodes 21 spaced apart, with a groove located between the two interdigital electrodes 21. Each interdigital electrode 21 comprises a first metal layer disposed on the substrate 10 and a second metal layer disposed on the first metal layer. The first metal layer is made of chromium and has a thickness of 50 nm; the second metal layer is made of gold and has a thickness of 200 nm. The interdigital electrodes 21 are comb-shaped electrodes with a total of 50 pairs of electrode fingers and a line width and line spacing of 100 μm.

[0065] The polymer layer 30 is made of polydimethylsiloxane;

[0066] 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, with a total volume of 150 μL. The inlet of the reaction chamber 31 is used to input a mixture of microplastic water samples and persulfate solution to form a Fenton-like reaction system, and the outlet is connected to the outlet of the microchannel for discharging the degraded water sample. The height of the microchannel in the reaction chamber 31 is 50 μm, which is tightly integrated with other membrane layers.

[0067] The photothermal catalyst layer 40, made of titanium dioxide with a thickness of 200 nm, completely covers the bottom of the reaction chamber 31 and reacts with the persulfate in the mixed water sample to form a Fenton-like reaction system to oxidatively degrade the mixed water sample. This layer generates heat through a photothermal conversion mechanism, stimulating photocatalysis and photothermal catalytic digestion. Applying an acoustic field causes the photothermal catalyst material to undergo dynamic deformation, promoting sonocatalysis.

[0068] 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:

[0069] (1) Preparation of flow cell mold: The 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 respectively. 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 50μm.

[0070] (2) Preparation of the polymer layer 30: polydimethylsiloxane and a curing agent are mixed in proportion and stirred thoroughly until uniform small bubbles appear 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 ends of the microchannel.

[0071] (3) Preparation of acoustic mold assembly 20: Provide a lithium niobate substrate and clean its surface. Then, place the lithium niobate substrate in an electron beam evaporation coating machine. After vacuuming, 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 board 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 assembly 20. The acoustic mold assembly 20 is also connected to an external radio frequency signal generator, a signal amplifier, and a power supply to promote the generation of surface acoustic waves.

[0072] (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;

[0073] (5) Preparation of the microplastic degradation device 100: The polymer layer 30 and the lithium niobate substrate are placed together 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.

[0074] Specifically, the microplastic degradation method provided in this embodiment 1 specifically includes the following steps:

[0075] (1) applying a radio frequency electric field to the acoustic mode assembly 20 to generate surface acoustic waves;

[0076] (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;

[0077] (3) The mixed solution of microplastics and persulfate is injected into the liquid input channel 311 from the inlet end and uniformly mixed in the microchannel;

[0078] (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, surface acoustic waves cause the substrate 10 to undergo mechanical deformation, and the deformation has a different electrode sequence from the material of the photothermal catalyst layer 40, generating an electric field on the photothermal catalyst layer 40, causing the electrons and holes generated by light in the photothermal catalyst layer 40 to move in different directions of electric potential, thereby enhancing the photothermal catalytic efficiency. The photothermal catalyst layer 40 absorbs incident light through the photothermal material and converts light energy into heat energy. This conversion process can achieve complete degradation through localized plasma heating, non-radiative relaxation of semiconductors, or thermal vibration of molecules.

[0079] (5) After degradation, the mixed water sample flows out from the output port through the liquid output channel 312.

[0080] In this embodiment, the area of ​​lithium niobate substrate 10 directly below reaction chamber 31 is covered with a photothermal catalytic film, which is the same size as the reaction chamber 31. This film is used to perform a photothermal-Fenton-like synergistic degradation of microplastics in water samples. The photothermal catalytic film creates a high-temperature, high-pressure environment beneath reaction chamber 31, leveraging the water pressure within the chamber to promote the development of a Fenton-like reaction.

[0081] The embodiment of the present application designs a microplastic degradation device 100 based on acoustic-photothermal synergistic catalysis, creating a combination of a microfluidic degradation chip and multiple enhancement effects, forming a new method for the rapid and complete degradation of microplastic water samples. By combining a microfluidic chip with multiple enhancement effects, it uses the synergistic reactions of photocatalysis, acoustic-photocatalysis, and photothermal catalysis simultaneously or separately to degrade microplastics. The microplastic degradation device 100 is small in size and consumes little energy, which 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, and can solve the existing problem of difficult degradation of microplastic water samples.

[0082] In summary, unlike some existing technologies, the embodiments of the present application design a microplastic degradation device 100 based on acoustic, photothermal synergistic catalysis, resulting in a combination of a microfluidic chip and multiple enhancement effects, forming a new method for the rapid and complete degradation of microplastic water samples. It uses photocatalysis, acoustic, photocatalysis, and photothermal catalysis to degrade microplastics simultaneously or separately. Compared with existing microplastic degradation technologies, the microplastic degradation device 100 can simultaneously utilize more catalytic reaction modes and have synergistic effects, which can achieve faster processing with lower energy consumption in the field of microplastic degradation and can shorten the degradation time to within a few minutes.

[0083] The above embodiments merely illustrate the implementation methods of the present invention. While the descriptions are relatively specific and detailed, they should not be construed as limiting the scope of the patent. It should be noted that a person skilled in the art could make various modifications and improvements without departing from the spirit of the present invention, all of which fall within the scope of protection of the present invention. Therefore, the scope of protection of the patent for this invention shall be determined by the appended claims.

Claims

1. A microplastic degradation device based on acoustic, photothermal and synergistic catalysis, characterized in that: The invention 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 provided inside the reaction chamber for thermally degrading the water sample to be tested after being irradiated with light; Wherein, the substrate comprises a lithium niobate substrate, and the acoustic mode assembly comprises two interdigital electrodes arranged at intervals.

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

3. The microplastic degradation device based on acoustic, photothermal synergistic catalysis according to claim 1 is characterized in that: The polymer layer is provided with a groove having a micro-channel near the bottom surface of the substrate. The groove and the substrate are combined to form the reaction chamber. The groove is located between the two interdigitated electrodes.

4. The microplastic degradation device based on acoustic, photothermal 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 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 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 synergistic catalysis according to claim 3 is characterized in that: A protective layer is further 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 synergistic catalysis according to claim 8, 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 and an outlet are respectively provided at both ends of the reaction chamber. The inlet is communicated with a liquid input channel, and the outlet is communicated with a liquid output channel.

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