Hydrodynamic cavitation catalysis-based degradation device and antibiotic wastewater degradation method thereof

Abstract

The invention relates to the technical field of degradation of hydrodynamic cavitation catalysis, in particular to a degradation device based on hydrodynamic cavitation catalysis and an antibiotic wastewater degradation method thereof, and the degradation device comprises the following steps: S1, adding antibiotic-containing wastewater into a liquid storage tank, and adding a preset amount of catalyst to enable the catalyst and the wastewater to form a uniform solid-liquid mixture, meanwhile, stirring and temperature control preparation is carried out on the liquid storage tank; s2, a water pump is started, so that the solid-liquid mixture enters a Venturi cavitation generator through a main circulation pipeline, a hydrodynamic cavitation effect is formed in a contraction section, a throat part and a diffusion section of the Venturi cavitation generator, and circulating flow is completed; the synthesized ternary ZIS / NFO / BC catalyst has the advantages of being high in stability, resistant to chemical corrosion, resistant to light corrosion and the like, and compared with a single hydrodynamic cavitation process or a single photocatalysis process, the hydrodynamic cavitation catalysis synergistic degradation process greatly improves the degradation efficiency of antibiotic doxycycline hydrochloride.

Description

Technical Field

[0001] This invention relates to the field of hydrocavitation catalysis degradation technology, specifically to a hydrocavitation catalysis-based degradation device and a method for degrading antibiotic wastewater. Background Technology

[0002] In recent years, hydrocavitation technology, as an emerging physical enhancement method, has been used to treat recalcitrant organic compounds due to the localized high temperature, high pressure, and strong oxidizing free radicals generated during bubble generation and collapse. However, hydrocavitation alone still suffers from problems in practical applications, such as low energy utilization, limited effective free radical yield, and insufficient degradation efficiency for certain structurally complex antibiotics. Therefore, researchers have attempted to combine hydrocavitation with photocatalysis to achieve complementarity in free radical generation pathways and activation methods. However, existing synergistic technologies are still limited by the following factors: insufficient coupling between the cavitation field and the illumination field, easy coverage of photocatalyst active sites by intermediate products, difficulty in catalyst separation and recovery, and high energy consumption of the reaction system. These limitations all affect the promotion of synergistic systems in engineering applications.

[0003] Furthermore, while existing photocatalyst materials, such as ZnIn2S4, NiFe2O4, and biochar, each possess their own advantages, single materials typically struggle to simultaneously achieve high photogenerated carrier separation efficiency, good structural stability, rapid electron migration capability, and recyclability. Therefore, the construction of multi-semiconductor composite or heterostructures has become a research hotspot in recent years. By using composite structures to achieve directional interfacial charge migration, enhance light absorption range, and increase active site exposure, the shortcomings of traditional photocatalysis can be overcome to some extent. However, how to achieve efficient utilization of composite semiconductor materials in dynamic flow fields and fully synergize with strong cavitation fields remains a challenge for current technologies.

[0004] In summary, given the high stability, recalcitrant nature, and insufficient efficiency of existing advanced oxidation methods in the treatment of antibiotic wastewater, there is an urgent need for a deep treatment technology that can effectively synergize the advantages of photocatalysis and cavitation enhancement, possess high mineralization capacity, facilitate catalyst recovery, and operate under mild conditions, in order to improve the removal efficiency of antibiotic pollutants and reduce environmental governance costs. Summary of the Invention

[0005] The purpose of this invention is to address the shortcomings of traditional photocatalysis by constructing various semiconductor composite or heterostructures, which has become a research hotspot in recent years. Composite structures enable directional migration of interfacial charges, enhance light absorption range, and increase the exposure of active sites. However, how to efficiently utilize composite semiconductor materials in dynamic flow fields and fully coordinate them with strong cavitation fields remains a challenge in existing technologies.

[0006] To achieve the above objectives, the present invention provides the following technical solution:

[0007] This invention provides a method for degrading antibiotic wastewater based on hydraulic cavitation catalysis, comprising the following steps:

[0008] S1. Add antibiotic-containing wastewater to the storage tank and add a preset amount of catalyst to form a uniform solid-liquid mixture with the catalyst and wastewater. At the same time, stir and control the temperature of the storage tank.

[0009] S2. Start the water pump so that the solid-liquid mixture enters the Venturi cavitation generator through the main circulation pipeline, where hydraulic cavitation is formed in its contraction section-throat-diffuser section and circulation is completed.

[0010] S3. Turn on the external light source so that the light acts on the fluid area near the Venturi cavitation generator, and works together with the extreme microenvironment generated by hydraulic cavitation to stimulate the active components on the catalyst surface.

[0011] S4. Under the continuous action of circulation and light, the free radicals, microjets and hot spots generated by hydraulic cavitation, together with the photogenerated charge carriers of the catalyst, participate in the decomposition, ring cracking and mineralization reaction of antibiotic molecules.

[0012] S5. When the reaction reaches the preset treatment time or degradation effect, stop the cycle, separate the treated wastewater from the catalyst, recover the catalyst for reuse, and obtain the treated wastewater effluent.

[0013] Furthermore, in step S1, the catalyst added to the storage tank is a ternary composite material ZnIn2S4 / NiFe2O4 / biochar (ZIS / NFO / BC), with an addition amount of 2.5g. The volume of antibiotic wastewater is 5.0L. A cooling water jacket is installed on the outer wall of the storage tank, and the temperature of the solid-liquid mixture in the storage tank is maintained at 25±2℃ by circulating cooling water.

[0014] Further, in step S2, the step of constructing the circulating cavitation flow field includes: starting the water pump, so that the solid-liquid mixture in the storage tank flows through the main circulation pipeline in sequence through the water pump, control valve, pressure gauge, Venturi cavitation generator and pressure gauge.

[0015] Furthermore, in step S2, hydraulic cavitation is formed in the contraction section-throat-diffusion section of the Venturi cavitation generator, so that the generation and collapse of cavitation bubbles continue to occur. During the circulation process, highly oxidizing hydroxyl radicals and superoxide ion radicals are generated, and the solid-liquid mixture completes closed-loop circulation flow in the main circulation pipeline.

[0016] Furthermore, in step S3, the external xenon lamp light source located below the Venturi cavitation generator is activated to provide continuous light irradiation as the solid-liquid mixture passes through the Venturi cavitation generator; the external light source is a 150W xenon lamp.

[0017] Furthermore, in step S4, under the condition that the solid-liquid mixture forms a cavitation bubble generation-collapse cycle through the Venturi cavitation generator and is continuously irradiated by an external light source, the high temperature, high pressure, microjets and hydroxyl radicals generated by cavitation, together with the photogenerated holes and superoxide ion radicals generated by the photocatalyst ZIS / NFO / BC under light irradiation, participate in the decomposition reaction of target molecules in antibiotic wastewater.

[0018] Furthermore, in step S4, the strong shear force and microjets induced by hydrocavitation promote the desorption of degradation intermediates on the surface of the photocatalyst, thereby continuously exposing catalytic active sites and improving degradation efficiency and mineralization degree.

[0019] Furthermore, in step S5, after the reaction is completed, the solid-liquid mixture is separated by an external magnetic field, so that the ternary composite photocatalyst containing NiFe2O4 component is quickly collected from the wastewater under the action of magnetic force, and the supernatant is subsequently filtered to obtain the degraded clear liquid.

[0020] Furthermore, in step S5, the catalyst can be reused after being washed with distilled water and dried at 60°C.

[0021] On the other hand, a degradation device based on hydrodynamic cavitation catalysis includes: a storage tank containing antibiotic wastewater and a catalyst solid-liquid mixture and a main circulation pipeline. The outer wall of the storage tank is provided with a cooling water jacket. The lower end of the cooling water jacket is provided with a circulating water inlet, and the upper end of the cooling water jacket is provided with a circulating water outlet. A magnetic stirring device is provided at the bottom of the storage tank, and a magnetic rotor is provided inside the storage tank. The main circulation pipeline starts at the bottom of the inner cavity of the storage tank and is kept in communication with the inside of the storage tank. The main circulation pipeline inputs circulating fluid into the tank through the upper part of the storage tank. The end of the main circulation pipeline is located above the liquid surface of the solid-liquid mixture. A water pump, a control valve 1, a pressure gauge 1, a cavitation generator, and a pressure gauge 2 are respectively provided from the starting end to the end of the main circulation pipeline.

[0022] The main circulation pipeline is connected in parallel with a circulation bypass. The circulation bypass starts from the pipeline between control valve 1 and pressure gauge 1. The end of the circulation bypass is located above the liquid surface of the solid-liquid mixture in the storage tank. A control valve 2 is installed on the circulation bypass. An external light source is placed above the storage tank and is located below the cavitation generator.

[0023] The throat of the cavitation generator is circular; the contraction section of the cavitation generator is a conical tube with a cone angle of 21° to 25°; the diffusion section of the cavitation generator is a conical tube with a cone angle of 5° to 9°; and the external light source is a 150W xenon lamp.

[0024] Beneficial effects

[0025] Compared with known public technologies, the technical solution provided by this invention has the following beneficial effects:

[0026] The ternary ZIS / NFO / BC catalyst synthesized in this invention exhibits strong stability, resistance to chemical corrosion, and resistance to photocorrosion. Compared with single hydrodynamic cavitation processes or single photocatalytic processes, the hydrodynamic cavitation catalytic synergistic degradation process significantly improves the degradation efficiency of the antibiotic doxycycline hydrochloride. The ternary ZIS / NFO / BC catalyst possesses a pn heterojunction nanostructure, which effectively inhibits the recombination of photogenerated electrons and holes. The biochar support exhibits electron conduction properties, further conducting photogenerated electrons and holes to the surface active sites, enhancing the catalytic effect. Simultaneously, the biochar support surface has high adsorption capacity, achieving targeted enrichment of antibiotic molecules to the reaction sites, effectively improving the catalytic degradation effect at the reaction kinetics level. The ternary ZIS / NFO / BC catalyst possesses nanoscale superparamagnetism, allowing for easy magnetic separation via an external magnetic field, greatly simplifying the recycling and reuse process. Attached Figure Description

[0027] Figure 1 This is a schematic diagram of the hydrocavitation degradation device of the present invention;

[0028] Figure 2 This is a schematic diagram of the hydraulic cavitation sterilization device of the present invention;

[0029] Figure 3 This is a schematic flowchart of the method of the present invention. Detailed Implementation

[0030] To enable those skilled in the art to better understand the present invention, the technical solutions of the present invention will be clearly and completely described below with reference to the accompanying drawings of the embodiments of the present invention. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort should fall within the scope of protection of the present invention.

[0031] It should be noted that the terms "first," "second," etc., in the specification, claims, and accompanying drawings of this invention are used to distinguish similar objects and are not necessarily used to describe a specific order or sequence. It should be understood that such data can be interchanged where appropriate so that the embodiments of the invention described herein can be implemented in orders other than those illustrated or described herein. Furthermore, the terms "comprising" and "having," and any variations thereof, are intended to cover a non-exclusive inclusion; for example, a process, method, system, product, or apparatus that comprises a series of steps or units is not necessarily limited to those steps or units explicitly listed, but includes other steps or units not explicitly listed or inherent to such processes, methods, products, or apparatus.

[0032] The present invention will now be described in further detail with reference to the accompanying drawings:

[0033] Example 1:

[0034] like Figure 1-3 As shown,

[0035] S1. Add antibiotic-containing wastewater to the storage tank and add a preset amount of catalyst to form a uniform solid-liquid mixture with the catalyst and wastewater. At the same time, stir and control the temperature of the storage tank.

[0036] Furthermore, in step S1, the catalyst added to the storage tank in step S1 is a ternary composite material ZnIn2S4 / NiFe3O4 / biochar (ZIS / NFO / BC), with an addition amount of 2.5g, and the volume of antibiotic wastewater is 5.0L. A cooling water jacket is installed on the outer wall of the storage tank, and the temperature of the solid-liquid mixture in the storage tank is maintained at 25±2℃ by circulating cooling water.

[0037] Specifically: S1.1: The storage tank in the constructed hydro-cavitation catalytic degradation device is equipped with a cooling water jacket on its outer wall. The bottom of the jacket is equipped with a circulating water inlet and the top is equipped with a circulating water outlet to maintain a stable system temperature. Before starting the S1 operation, a magnetic rotor of the appropriate specification is placed at the installation position at the bottom of the storage tank using a magnetic stirring device to ensure that sufficient hybrid power can be provided subsequently.

[0038] S1.2: The antibiotic chosen was doxycycline hydrochloride, which was prepared to the target concentration according to experimental requirements;

[0039] The operation is as follows:

[0040] Weigh out an appropriate amount of doxycycline hydrochloride solid powder.

[0041] Dissolve and prepare a 30 mg / L antibiotic waste water solution using deionized water;

[0042] The resulting 5.0L antibiotic wastewater was directly poured into the inner cavity of the storage tank (1);

[0043] To ensure system uniformity, the magnetic stirrer is turned on after the wastewater is added to slowly stir the liquid.

[0044] S1.3: Catalyst preparation: The ternary heterojunction composite catalyst ZIS / NFO / BC prepared by the present invention consists of three parts: ZnIn2S4 (ZIS); NiFe2O4 (NFO); and biochar.

[0045] The catalyst is a black powder with superparamagnetic properties, a pn heterojunction structure, and high adsorption capacity.

[0046] The catalyst addition procedure is as follows:

[0047] Weigh out 2.5g of ZIS / NFO / BC powder;

[0048] Disperse the catalyst into the already stirred antibiotic wastewater to initially and uniformly suspend it;

[0049] Stir for about 3–5 minutes to fully wet the catalyst and mix it with the wastewater.

[0050] S1.4: Since subsequent hydraulic cavitation will generate heat, the cooling system needs to be turned on in advance: introduce circulating cooling water through the cooling water inlet, adjust the flow rate to stabilize the temperature in the storage tank at 25±2℃, and the cooling water flows out from the outlet to form a closed loop.

[0051] S1.5: After mixing the antibiotic wastewater and the catalyst, the following solid-liquid mixed reaction precursor system is formed: antibiotic wastewater + ternary catalyst (ZIS / NFO / BC). After magnetic stirring for about 10 minutes, the following results are obtained:

[0052] The catalyst is evenly distributed, and the biochar increases the adsorption capacity, so that antibiotic molecules are initially enriched on the catalyst surface. The initial solid and liquid fine particles are well dispersed, ready to enter the subsequent hydraulic cavitation cycle.

[0053] S2. Start the water pump to allow the solid-liquid mixture to enter the Venturi cavitation generator through the main circulation pipeline, where hydraulic cavitation is formed in its contraction section-throat-diffuser section and circulation is completed.

[0054] Further, in step S2,

[0055] In the process of hydro-cavitation catalytic degradation of antibiotic wastewater, wastewater containing doxycycline hydrochloride (5.0L volume) and ternary composite catalyst ZIS / NFO / BC (2.5g dosage) are first added to a storage tank, and the solid and liquid are fully mixed by a magnetic stirring device. Then, a circulating cavitation flow field is constructed.

[0056] The steps to construct a cyclic cavitation flow field are as follows:

[0057] S2.1: Start the water pump in the main circulation system to draw the solid-liquid mixture into the pipeline from the inlet of the main circulation pipeline at the bottom of the storage tank, and let it flow through the water pump, control valve 1 and pressure gauge 1 in sequence. After the inlet pressure at pressure gauge 1 reaches the set pressure range (e.g., 1.0 to 5.0 bar), the mixture enters the contraction section of the Venturi cavitation generator;

[0058] S2.2: In the contraction section, as the effective channel cross-sectional area gradually decreases, the linear velocity of the solid-liquid mixture rapidly increases, the local pressure decreases, and a large number of cavitation nuclei form in the fluid. When the mixture enters the Venturi throat, it reaches the lowest pressure state, and bubbles grow rapidly. In the diffusion section, the channel area gradually increases, the local pressure rises again, causing the cavitation bubbles to collapse instantaneously, forming local extreme physicochemical conditions, including high temperature (up to 15000K), high pressure (up to 1000 atm), high-speed microjets, and strong shearing.

[0059] S2.3: These extreme conditions promote the splitting of water molecules, generating hydroxyl radicals (·OH) with strong oxidizing power and a small amount of superoxide radicals (O2·-), which promote the ring-opening oxidation and continuous degradation of doxycycline hydrochloride. In addition, due to the presence of the catalyst ZIS / NFO / BC, the photogenerated carriers precipitated on its surface and the active species generated by cavitation work together to further improve the oxidation efficiency.

[0060] S2.4: The cavitation mixture is pressure monitored by a pressure gauge and then transported back to the upper part of the storage tank through the main circulation pipeline, so that it is sprayed back to the solid-liquid interface to achieve continuous circulation. This circulation process can maintain a stable cavitation collapse frequency and a high-efficiency free radical generation rate, ensuring that the antibiotic wastewater is in a highly efficient cavitation oxidation environment throughout the entire reaction cycle, thereby significantly improving the degradation rate and mineralization degree.

[0061] S3. Turn on the external light source so that the light acts on the fluid area near the Venturi cavitation generator, and works together with the extreme microenvironment generated by hydraulic cavitation to stimulate the active components on the catalyst surface.

[0062] Furthermore, in S3, an external xenon lamp light source positioned below the Venturi cavitation generator is activated to provide continuous light irradiation as the solid-liquid mixture passes through the Venturi cavitation generator. This external light source is a 150W xenon lamp, which can further promote the generation of photogenerated holes and reactive oxygen species on the catalyst surface under the high temperature, high pressure, and luminescence conditions in the cavitation micro-region. This, in turn, synergistically enhances the degradation and mineralization efficiency of the antibiotic with the hydroxyl radicals generated by cavitation. After the cyclic cavitation flow field in S2 has stabilized, a photo-cavitation synergistic step is further performed to improve degradation efficiency.

[0063] Specifically: S3.1: Directly below the Venturi cavitation generator (with a circular throat, a conical angle of 21° to 25° in the contraction section, and a conical angle of 5° to 9° in the diffusion section), install an external xenon lamp light source with a power of 150W. This light source corresponds to the transparent window area above the liquid storage tank, so that the light can directly illuminate the solid-liquid mixture flowing through the Venturi cavitation generator in the main circulation pipeline.

[0064] S3.2: After the water pump continues to run and the solid-liquid mixture passes through the Venturi tube to form a cavitation micro-region, turn on the external xenon lamp light source to generate broadband visible light and some ultraviolet light. Light irradiation can excite the surface of the ternary ZIS / NFO / BC catalyst to generate photogenerated electrons and holes, promoting the formation of superoxide radicals (·O2). - The formation of active substances such as Venturi cavitation. At the same time, the collapse of cavitation bubbles caused by Venturi cavitation can instantaneously generate local high temperature (up to 15000K), high pressure (up to 1000atm), microjets and high-speed shear force.

[0065] S3.3: Under the synergistic effect of light and cavitation, three types of reactive oxygen species (photogenerated holes, ·O2) - ·O2 and ·OH) jointly participate in the degradation process of doxycycline hydrochloride, in which photogenerated holes promote the removal of functional groups, and ·O2 - It participates in electron transfer reactions, while the ·OH generated by cavitation rapidly ring-cleaves the doxycycline molecular skeleton, causing the antibiotic molecule to gradually decompose into small molecule intermediates, ultimately achieving mineralization into terminal products such as CO2, H2O and inorganic ions.

[0066] S4. Under the continuous action of circulation and light, the free radicals, microjets and hot spots generated by hydraulic cavitation, together with the photogenerated charge carriers of the catalyst, participate in the decomposition, ring cracking and mineralization reaction of antibiotic molecules.

[0067] Furthermore, in step S4, the step of achieving hydrocavitation-photocatalytic synergistic degradation includes: under the condition that the solid-liquid mixture forms a cavitation bubble generation-collapse cycle through a Venturi cavitation generator and is continuously irradiated by an external light source, the high temperature, high pressure, microjets and hydroxyl radicals generated by cavitation, together with the photogenerated holes and superoxide ion radicals generated by the photocatalyst ZIS / NFO / BC under light irradiation, participate in the decomposition reaction of target molecules in antibiotic wastewater. The strong shear force and microjets induced by hydrocavitation promote the desorption of degradation intermediates on the surface of the photocatalyst, thereby continuously exposing catalytic active sites and improving degradation efficiency and mineralization degree.

[0068] S4.1: After completing the establishment of the circulating cavitation flow field in S2 and the photo-enhancing effect in S3, the process proceeds to the hydro-cavitation-photocatalytic synergistic degradation step. In this embodiment, the antibiotic used is doxycycline hydrochloride (initial concentration 30 mg / L), the catalyst is a ternary composite material ZIS / NFO / BC (dosage 2.5 g), and the wastewater volume is 5.0 L.

[0069] S4.2: Once the main circulation system is running stably, the solid-liquid mixture continuously enters the Venturi cavitation generator. In the Venturi contraction section, the rapid increase in liquid velocity leads to a significant decrease in local pressure, and a large number of cavitation nuclei begin to form. When the minimum pressure is reached at the throat, a large number of tiny cavitation bubbles grow rapidly. Upon entering the diffusion section, the pressure recovers, causing the cavitation bubbles to collapse instantaneously.

[0070] The collapse of cavitation bubbles produces the following extreme reaction conditions:

[0071] Localized high temperatures can reach approximately 15,000 K;

[0072] Localized high pressure can reach approximately 1000 atm;

[0073] This generates high-speed microjets and intense shear fields.

[0074] It generates strong oxidizing hydroxyl radicals (·OH) and a small amount of superoxide radicals (O2·-).

[0075] S4.3: A 150W xenon lamp installed below the Venturi generator continuously provides light irradiation to the solid-liquid mixture, exciting photogenerated electron-hole pairs in the ternary ZIS / NFO / BC catalyst. ZIS (ZnIn2S4), as a narrow bandgap semiconductor, provides light absorption, while the conductivity and heterostructure of NFO (NiFe2O4) and biochar suppress photogenerated carrier recombination, allowing photogenerated holes (h+) and superoxide radicals (O2·-) to maintain high reactivity on the catalyst surface.

[0076] S4.3: The concerted reaction mechanism is as follows:

[0077] S4.3.1: Cavitation increases the amount of free radicals generated.

[0078] Cavitation bubble collapse cleaves water molecules to produce a large amount of ·OH, which has strong oxidizing properties and can rapidly cause ring cleavage, deamination and decarboxylation reactions of doxycycline hydrochloride molecules.

[0079] S4.3.2: Photocatalysis promotes electron-hole separation:

[0080] Xenon lamp illumination excites the catalyst to generate electron-hole pairs. Holes can directly oxidize target molecules or water molecules, while photogenerated electrons can combine with O2 to generate O2·-, which participates in further oxidative decomposition.

[0081] S4.3.3: Cavitation-enhanced photocatalytic active site regeneration:

[0082] The cavitation microjets and shear forces can wash away the intermediate products adsorbed on the catalyst surface, preventing them from covering the active sites, thereby restoring the effective sites on the catalyst surface, maintaining high photogenerated carrier participation, and improving the overall catalytic efficiency.

[0083] S4.3.4: The combined action of three types of reactive oxygen species achieves deep degradation and mineralization:

[0084] ·OH (from cavitation), h+ (from photocatalysis), and O2·- (from composite catalysis) work together to degrade doxycycline into small molecule intermediates, and finally to CO2, H2O and inorganic ions.

[0085] S4.3.5: The structural advantages of the ternary catalyst ZIS / NFO / BC further enhance the reaction:

[0086] Heterogeneous structures facilitate directional electron migration;

[0087] Biochar pore adsorption enhances local concentration, enabling targeted enrichment of the reaction.

[0088] Magnetic NFO allows the catalyst to be repeatedly recovered.

[0089] It achieves a degradation efficiency far exceeding that of single photocatalysis or single hydrocavitation within the same reaction time, and effectively improves the degree of mineralization, so that doxycycline hydrochloride is eventually converted into harmless small molecule substances.

[0090] S5. When the reaction reaches the preset treatment time or degradation effect, stop the cycle, separate the treated wastewater from the catalyst, recover the catalyst for reuse, and obtain the treated wastewater effluent.

[0091] Further, in step S5,

[0092] After the reaction, the solid-liquid mixture is separated by an external magnetic field, allowing the ternary composite photocatalyst containing NiFe2O4 to be rapidly collected from the wastewater under magnetic force. The supernatant is then filtered to obtain the degraded clear liquid. The catalyst can be reused after being washed with distilled water and dried at 60°C.

[0093] This embodiment illustrates the post-treatment of the reaction system and the catalyst separation process after completing the S4 hydrocavitation-photocatalytic synergistic degradation step.

[0094] When the reaction reaches the set time point (60 minutes), the circulating water pump and external light source are turned off, stopping the circulation of the solid-liquid mixture. Since the photocatalyst used is a ternary composite material ZIS / NFO / BC, where NFO (NiFe2O4) exhibits significant magnetic properties, it can be rapidly separated using an external magnetic field.

[0095] The specific operating steps are as follows:

[0096] S5.1: Place a strong magnet (magnetic induction intensity of about 0.35T) at the bottom of the outer wall of the reaction tank and keep the solid-liquid mixture in a static state for about 3–5 minutes. At this time, the catalyst particles containing NiFe2O4 will rapidly gather and fix to the bottom of the container under the action of the magnetic field, forming a stable catalyst deposition layer.

[0097] S5.2: Slowly remove the supernatant using a siphon or drain outlet, avoiding disturbance to the magnetic precipitate layer. The resulting supernatant is essentially free of catalyst and can be used for subsequent detection or pretreatment before discharge.

[0098] S5.3: Further filtration through a 0.45μm filter membrane to ensure no suspended solids.

[0099] Depending on the experimental requirements, the filtrate was subjected to UV-Vis or LC-MS analysis to monitor changes in antibiotic degradation products.

[0100] S5.4: After the magnetic field is turned off, the catalyst adsorbed at the bottom of the container is rinsed with distilled water 2–3 times to remove intermediate products, degradation residues and some inorganic ions adsorbed on its surface, thereby keeping the active sites on the catalyst surface clean.

[0101] S5.5: The washed catalyst is dried in an oven at 60℃ for 6–8 hours to obtain a dried, reusable catalyst. Due to the high structural stability and good magnetic separation properties of the ternary ZIS / NFO / BC composite material, it can maintain high activity even after multiple cycles of use.

[0102] S5.6: Clean the Venturi cavitation generator, main circulation pipeline, and storage tank in preparation for the next batch of reactions. The cleaning solution can be treated to render it harmless in accordance with laboratory waste management requirements.

[0103] Example 2: Add catalyst (2.5g) and wastewater containing antibiotics (5.0L volume) to the storage tank, start the magnetic stirring device, and place the corresponding magnetic rotor in the storage tank. After the water pump is started, this solid-liquid mixture begins to circulate through the main circulation pipeline. At the same time, turn on the external light source to generate light and heat in conjunction with the hydraulic cavitation effect, and a hydraulic cavitation catalytic degradation reaction occurs.

[0104] Without adding a catalyst, turning on an external light source, starting a magnetic stirrer, or adding a corresponding magnetic rotor to the storage tank, the initial concentration of antibiotic wastewater is set to 30 mg / L, and the inlet pressure of the Venturi cavitation generator is set to 1.0–5.0 bar.

[0105] Without turning on the water pump, the solid-liquid mixture in the storage tank does not flow into the main circulation pipeline and the circulation bypass.

[0106] Furthermore, the catalyst is a ternary composite powder material composed of ZnIn2S4, NiFe2O4, and biochar.

[0107] This invention creatively proposes a hydro-cavitation-photocatalytic synergistic method for the degradation of antibiotics:

[0108] Hydrodynamic cavitation provides extreme conditions such as high temperature (up to 15000 K), high pressure (up to 1000 atm), hot spots, and luminescence. These extreme conditions lead to the generation of highly oxidizing species, hydroxyl radicals and superoxide radicals, which break down doxycycline hydrochloride molecules into smaller intermediates. Hydrodynamic cavitation also promotes the degradation efficiency of the photocatalyst. Under illumination, active components are generated on the surface of the photocatalyst, which convert doxycycline hydrochloride molecules into smaller intermediates. These intermediates can adsorb onto the photocatalyst surface and hinder the adsorption of doxycycline hydrochloride molecules at active sites, thereby reducing mass transfer efficiency. Simultaneously, photons cannot reach the covered active sites, affecting the number of photogenerated charge carriers and thus reducing photodegradation efficiency. In the synergistic process of hydrodynamic cavitation and photocatalysis, the mechanical action of hydrodynamic cavitation (due to the high shear force and microjets generated by cavitation collapse) instantaneously washes the photocatalyst surface, causing desorption of intermediates, thereby restoring mass transfer and the adsorption capacity for doxycycline hydrochloride, thus enhancing photodegradation activity. Simultaneously, photocatalysis enhances the degradation efficiency of hydraulic cavitation. A key factor affecting the degradation efficiency of hydraulic cavitation is the cavitation intensity of the fluid within the Venturi tube. There are two methods to improve the hydraulic cavitation intensity: one is to optimize the structure and operating parameters of the Venturi tube, which has been accomplished in this invention. The other is to introduce solid powder into the fluid. The reinforcing effect of the solid powder can be attributed to the gas molecules dissolved on its surface. These dissolved gas molecules are typically present in the pores of the solid powder and then develop into stable cavitation nuclei. This so-called heterogeneous nucleation process significantly weakens the free energy barrier, lowers the cavitation threshold, and thus improves the cavitation intensity and degradation performance. The synergistic effect between hydraulic cavitation and photocatalysis can also be attributed to the influence of active groups. As previously stated, the photocatalytic process in this invention mainly generates photogenerated holes, produces limited superoxide radicals, and lacks the participation of hydroxyl radicals. This results in the generation of various intermediate products, but very limited ring-cracking products. Meanwhile, the hydraulic cavitation process in this paper mainly generates hydroxyl radicals, while also producing a small amount of superoxide radicals. The main intermediates originate from ring-breaking reactions due to the high oxidizing power of hydroxyl radicals. Therefore, in the hydrodynamic cavitation catalytic synergistic process, all three types of radicals participate in the degradation reaction. Hydroxyl radicals accelerate the disintegration of the carbon ring, while photogenerated holes and superoxide ion radicals lead to the decomposition of various functional groups. The synergistic effect among reactive oxygen species enhances the degradation and mineralization efficiency of doxycycline hydrochloride, ultimately converting it into carbon dioxide, water, and other inorganic molecules.

[0109] On the other hand, a degradation device based on hydrodynamic cavitation catalysis,

[0110] The system is equipped with a storage tank containing antibiotic wastewater and catalyst. A cooling water jacket is installed around the storage tank. A circulating water inlet is located at the lower end of the jacket, and a circulating water outlet is located at the upper end. Magnetic stirring devices are installed at the bottom of the storage tank and the cooling water jacket, and a corresponding magnetic rotor is placed inside the storage tank. The main circulation pipeline starts at the bottom of the inner cavity of the storage tank and is kept in communication with the inside of the storage tank. The main circulation pipeline finally inputs circulating fluid into the tank through the upper part of the storage tank, and the pipeline end is located above the liquid surface of the solid-liquid mixture. A water pump, control valve 1, pressure gauge 1, Venturi cavitation generator, and pressure gauge 2 are installed from the starting end to the end of the main circulation pipeline.

[0111] Furthermore, the hydraulic cavitation catalytic degradation device incorporates a bypass in parallel with the main circulation pipeline. The bypass originates in the pipeline between control valve 1 and pressure gauge 1, and terminates above the surface of the solid-liquid mixture in the storage tank. Control valve 2 is installed on the bypass. An external light source is placed above the storage tank and below the Venturi cavitation generator.

[0112] Furthermore, in the hydrodynamic cavitation catalytic degradation device, the throat of the Venturi cavitation generator installed in the main circulation pipeline is circular; the contraction section of the Venturi cavitation generator is a conical tube with a cone angle of 21° to 25°; the diffusion section of the Venturi cavitation generator is a conical tube with a cone angle of 5° to 9°; and the external light source is a 150W xenon lamp.

[0113] The above embodiments are only used to illustrate the technical solutions of the present invention, and are not intended to limit it. Although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some of the technical features. Such modifications or substitutions will not cause the essence of the corresponding technical solutions to deviate from the spirit and scope of the technical solutions of the embodiments of the present invention.

Claims

1. A method for degrading antibiotic wastewater based on hydraulic cavitation catalysis, characterized in that, Includes the following steps: S1. Add antibiotic-containing wastewater to the storage tank and add a preset amount of catalyst to form a uniform solid-liquid mixture with the catalyst and wastewater. At the same time, stir and control the temperature of the storage tank. S2. Start the water pump so that the solid-liquid mixture enters the Venturi cavitation generator through the main circulation pipeline, where hydraulic cavitation is formed in its contraction section-throat-diffuser section and circulation is completed. S3. Turn on the external light source so that the light acts on the fluid area near the Venturi cavitation generator, and works together with the extreme microenvironment generated by hydraulic cavitation to stimulate the active components on the catalyst surface. S4. Under the continuous action of circulation and light, the free radicals, microjets and hot spots generated by hydraulic cavitation, together with the photogenerated charge carriers of the catalyst, participate in the decomposition, ring cracking and mineralization reaction of antibiotic molecules. S5. When the reaction reaches the preset treatment time or degradation effect, stop the cycle, separate the treated wastewater from the catalyst, recover the catalyst for reuse, and obtain the treated wastewater effluent.

2. The method for degrading antibiotic wastewater based on hydraulic cavitation catalysis according to claim 1, characterized in that, In step S1, the catalyst added to the storage tank is a ternary composite material ZnIn2S4 / NiFe2O4 / biochar (ZIS / NFO / BC), with an addition amount of 2.5g. The volume of antibiotic wastewater is 5.0L. A cooling water jacket is installed on the outer wall of the storage tank, and the temperature of the solid-liquid mixture in the storage tank is maintained at 25±2℃ by circulating cooling water.

3. The method for degrading antibiotic wastewater based on hydraulic cavitation catalysis according to claim 2, characterized in that, In step S2, the step of constructing the circulating cavitation flow field includes: starting the water pump, so that the solid-liquid mixture in the storage tank flows through the main circulation pipeline in sequence through the water pump, control valve, pressure gauge, Venturi cavitation generator and pressure gauge.

4. The method for degrading antibiotic wastewater based on hydraulic cavitation catalysis according to claim 3, characterized in that, In step S2, hydraulic cavitation is formed in the contraction section-throat-diffusion section of the Venturi cavitation generator, so that the generation and collapse of cavitation bubbles continue to occur. During the circulation process, strong oxidizing hydroxyl radicals and superoxide ion radicals are generated, and the solid-liquid mixture completes closed-loop circulation flow in the main circulation pipeline.

5. The method for degrading antibiotic wastewater based on hydraulic cavitation catalysis according to claim 4, characterized in that, In step S3, the external xenon lamp light source located below the Venturi cavitation generator is activated to provide continuous light irradiation as the solid-liquid mixture passes through the Venturi cavitation generator; the external light source is a 150W xenon lamp.

6. The method for degrading antibiotic wastewater based on hydraulic cavitation catalysis according to claim 5, characterized in that, In step S4, under the condition that the solid-liquid mixture forms a cavitation bubble generation-collapse cycle through the Venturi cavitation generator and is continuously irradiated by an external light source, the high temperature, high pressure, microjets and hydroxyl radicals generated by cavitation, together with the photogenerated holes and superoxide ion radicals generated by the photocatalyst ZIS / NFO / BC under light irradiation, participate in the decomposition reaction of target molecules in antibiotic wastewater.

7. The method for degrading antibiotic wastewater based on hydraulic cavitation catalysis according to claim 6, characterized in that, In step S4, the strong shear force and microjets induced by hydrocavitation cause the degradation intermediates on the surface of the photocatalyst to desorb, thereby continuously exposing the catalytic active sites and improving the degradation efficiency and mineralization degree.

8. The method for degrading antibiotic wastewater based on hydraulic cavitation catalysis according to claim 7, characterized in that, In step S5, after the reaction is completed, the solid-liquid mixture is separated by an external magnetic field, so that the ternary composite photocatalyst containing NiFe2O4 component is quickly collected from the wastewater under the action of magnetic force, and the supernatant is then filtered to obtain the degraded clear liquid.

9. The method for degrading antibiotic wastewater based on hydraulic cavitation catalysis according to claim 8, characterized in that, In step S5, the catalyst can be reused after being washed with distilled water and dried at 60°C.

10. A degradation device based on hydrodynamic cavitation catalysis, comprising a method for degrading antibiotic wastewater based on hydrodynamic cavitation catalysis according to any one of claims 1-9, characterized in that, The entire system is constructed in a closed-loop circulation system, including: a storage tank containing antibiotic wastewater and a catalyst solid-liquid mixture and a main circulation pipeline. The outer wall of the storage tank is equipped with a cooling water jacket. The lower end of the cooling water jacket is equipped with a circulation water inlet, and the upper end of the cooling water jacket is equipped with a circulation water outlet. A magnetic stirring device is installed at the bottom of the storage tank, and a magnetic rotor is installed inside the storage tank. The main circulation pipeline starts at the bottom of the inner cavity of the storage tank and is kept in communication with the inside of the storage tank. The main circulation pipeline inputs circulating fluid into the tank through the upper part of the storage tank. The end of the main circulation pipeline is located above the liquid surface of the solid-liquid mixture. A water pump, control valve 1, pressure gauge 1, cavitation generator, and pressure gauge 2 are respectively installed from the starting end to the end of the main circulation pipeline. The main circulation pipeline is connected in parallel with a circulation bypass. The circulation bypass starts from the pipeline between control valve 1 and pressure gauge 1. The end of the circulation bypass is located above the liquid surface of the solid-liquid mixture in the storage tank. A control valve 2 is installed on the circulation bypass. An external light source is placed above the storage tank and is located below the cavitation generator. The throat of the cavitation generator is circular; the contraction section of the cavitation generator is a conical tube with a cone angle of 21° to 25°; the diffusion section of the cavitation generator is a conical tube with a cone angle of 5° to 9°; and the external light source is a 150W xenon lamp.

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