Method and device for hydrogen production by photocatalytic swirling of organic wastewater

Abstract

The present disclosure relates to a method and device for hydrogen production from organic wastewater by photocatalysis and cyclone strengthening, and provides a method for hydrogen production from organic wastewater by photocatalysis and cyclone strengthening, which comprises the following steps: (A) mixing the catalyst with the wastewater by shearing oscillation, (B) hydrogen production from the wastewater by photocatalysis and cyclone oscillation, and (C) separation of the gas-liquid-solid three phases and reuse of the catalyst. The present disclosure also provides a device for hydrogen production from organic wastewater by photocatalysis and cyclone strengthening. The present disclosure makes the organic pollutants in water decomposed under the action of the catalyst, and the chemical energy of the organic pollutants is recovered in the form of hydrogen, so that the hydrogen production from wastewater by photocatalysis and wastewater treatment are coordinated, the reaction rate of the hydrogen production from wastewater by photocatalysis is improved, and the secondary pollution caused by the catalyst is avoided.

Description

Technical Field

[0001] This disclosure pertains to the field of photocatalytic hydrogen production from wastewater, and relates to a method and apparatus for photocatalytic cyclone-enhanced hydrogen production from organic wastewater. Background Technology

[0002] Hydrogen energy is a clean energy source with high energy density, zero pollution, and wide applications. Utilizing photocatalytic oxidation of organic wastewater to produce hydrogen is considered a promising comprehensive solution to energy consumption and environmental problems. High-concentration organic wastewater from chemical plants is characterized by poor biodegradability and high biotoxicity. High-concentration organic wastewater is typically treated using advanced oxidation technologies such as Fenton oxidation to reduce biotoxicity and improve biodegradability before further biological treatment. However, this technology is costly and contradicts the initial goal of resource recovery. In contrast, photocatalytic hydrogen production from wastewater generates hydroxyl radicals to oxidize and decompose organic matter. Simultaneously, the photogenerated electrons from the catalyst combine with hydrogen ions in the solution to generate hydrogen gas, achieving a synergistic goal of wastewater treatment and resource recovery.

[0003] To improve the reaction efficiency and industrial application of photocatalytic hydrogen production from wastewater, increase the utilization rate of light energy, and solve problems such as low photocatalytic efficiency of reactors, poor effluent quality, and difficulty in separating catalysts from wastewater, researchers are currently focusing on reactor design and optimization of separation methods.

[0004] In reactor design, the arrangement of the reaction light source and the overall reactor design are key areas of focus for many researchers seeking optimization. A well-designed combination of light source placement and reactor design can significantly improve the photocatalytic reaction rate within the system. Chinese invention patent application CN 117902673A discloses a packed-bed photocatalytic reactor, characterized by the use of a top-illuminated UV lamp to excite a photocatalytic degradation reaction between a solid catalyst attached to quartz glass and the solution after the removal of suspended matter. While removing suspended particles effectively reduces light source loss, the top-illuminated structure hinders effective light distribution. The quartz glass-like packing catalyst, placed in the reactor, suffers from low photocatalytic efficiency due to its low specific surface area and the potential for large catalyst particles to obstruct each other.

[0005] Chinese invention patent application CN 117504773A discloses a photocatalytic hydrogen production device, characterized by a serpentine spherical expansion tube as the photocatalytic reactor, with a UV lamp placed inside the tube as the light source. Although the expansion tube can increase the residence time compared to a straight tube, its improvement in solution turbulence is very limited. Furthermore, the expansion section has a slower flow velocity near the wall, easily creating dead zones that cause catalyst deposition on the reactor wall, thus affecting subsequent photocatalytic reactions. This jacketed design also hinders the cleaning and maintenance of the device, limiting its industrial application prospects.

[0006] Furthermore, the rate of photocatalytic hydrogen production from wastewater is significantly affected by the catalyst. Smaller catalyst particles result in a larger specific surface area and a higher reaction rate. However, smaller catalysts also make separation from the solution more difficult. Catalyst residues during wastewater treatment can cause secondary pollution. Therefore, efficient and low-cost catalyst separation is one of the main challenges facing the industrial application of photocatalytic hydrogen production from wastewater.

[0007] Therefore, in order to improve the efficiency of photocatalytic hydrogen production from wastewater and the separation and recovery of catalysts in solution, there is an urgent need in the field to develop a method and apparatus that can overcome the above-mentioned technical defects. Summary of the Invention

[0008] This disclosure provides a novel method and apparatus for photocatalytic cyclone-enhanced hydrogen production from organic wastewater, which can efficiently remove organic matter from organic wastewater and recover its chemical energy in the form of hydrogen. This treatment method is cleaner and more efficient, the equipment is simple, the investment cost is low, and it does not produce secondary pollution, thus solving the problems existing in the prior art.

[0009] On the one hand, this disclosure provides a method for photocatalytic cyclone-enhanced hydrogen production from organic wastewater, the method comprising the following steps:

[0010] (A) Shearing and oscillating mixing of catalyst and wastewater: The catalyst particles and organic wastewater are initially sheared and mixed using a swirling flow field, and then the resulting initial mixture is oscillated and mixed using the Venturi effect to obtain a uniformly dispersed mixed solution of catalyst.

[0011] (B) Wastewater vortex oscillation photocatalytic hydrogen production: The mixed solution obtained in step (A) is controlled to undergo three-dimensional rotating turbulent motion to form a vortex field, and a light source is introduced at the center of the vortex field for photocatalytic hydrogen production, thereby obtaining a three-phase mixed solution containing catalyst particles, wastewater, and hydrogen; and

[0012] (C) Gas-liquid-solid three-phase separation and catalyst recycling: Centrifugation is used to separate the catalyst particles, hydrogen and wastewater by utilizing the density difference between the three to obtain the catalyst particle solid phase, the hydrogen-containing gas phase and the treated liquid phase. The catalyst particle solid phase is returned to the treatment process in step (A) for recycling.

[0013] In a preferred embodiment, in step (A), the COD content of the organic wastewater is 500-6000 mg / L; the particle size of the catalyst particles is 50-600 μm, and the catalyst includes COFs or TiO2.

[0014] On the other hand, this disclosure provides a photocatalytic cyclone-enhanced hydrogen production device for organic wastewater, the device comprising:

[0015] The reactor consists of a cyclone mixer, a cyclone photocatalytic reactor, a water pump, and a cyclone gas-liquid-solid three-phase separator. The cyclone mixer, cyclone photocatalytic reactor, and cyclone gas-liquid-solid three-phase separator constitute a primary reaction unit. The outlet of the mixed solution from the cyclone mixer is connected to the dual tangential cyclone inlet of the cyclone photocatalytic reactor. The three-phase mixed solution of wastewater, catalyst particles, and hydrogen from the photocatalytic hydrogen production process is discharged from the bottom outlet of the cyclone photocatalytic reactor, pressurized by the water pump, and then discharged from the water pump outlet. The catalyst particles enter the cyclone gas-liquid-solid three-phase separator through the tangential inlet for gas-liquid-solid three-phase separation, obtaining a catalyst particle solid phase, a hydrogen-containing gas phase, and a treated liquid phase. The catalyst particle solid phase is discharged from the solid phase outlet of the cyclone gas-liquid-solid three-phase separator and returned to the cyclone mixer through the catalyst inlet of the mixer connected to the solid phase outlet. The treated liquid phase is discharged from the liquid phase outlet of the cyclone gas-liquid-solid three-phase separator and returned to the cyclone mixer through the liquid phase tangential inlet of the mixer connected to the liquid phase outlet.

[0016] In a preferred embodiment, the apparatus further includes a carbon dioxide absorption tower, wherein a hydrogen-containing gaseous phase is discharged from the gaseous outlet of a cyclone gas-liquid-solid three-phase separator and enters the carbon dioxide absorption tower.

[0017] In another preferred embodiment, the number of reaction stages increases according to the increase in COD content of the organic wastewater, including 1-4 stages; the reflux ratio of the treated liquid phase is 2:1 to 4:1.

[0018] In another preferred embodiment, when the COD content is 500 mg / L to less than 1000 mg / L, a single-stage treatment is used; when the COD content is 1000 mg / L to less than 3000 mg / L, a two-stage series treatment is used; when the COD content is 3000 mg / L to less than 4500 mg / L, a three-stage series treatment is used; and when the COD content is 4500-6000 mg / L, a four-stage series treatment is used.

[0019] In another preferred embodiment, the cyclone mixer includes: a tangential liquid phase inlet, a mixer column, a catalyst distributor, a Venturi mixing section, a mixed solution outlet, and a catalyst inlet; wherein, the tangential liquid phase inlet is located at the bottom of the mixer column, and the catalyst distributor is coaxially disposed at the bottom of the mixer column; the Venturi mixing section consists of two spherical shells with decreasing diameters, located above the mixer column, and connected to the mixed solution outlet;

[0020] The ratio of the diameter D1 of the cyclone mixer to the height H1 of the mixer column is 1:2, and the diameter D of the catalyst distributor is... 12 The ratio is 0.5D1, and the ratio of the spherical shell radius R1:R2 of the Venturi mixed segment is 2:1.

[0021] In another preferred embodiment, the swirling photocatalytic reactor includes: a reactor column section, a reactor cone section, a dual-tangential swirling inlet, a central light source, an anti-vortex baffle, and a bottom outlet; wherein, the dual-tangential swirling inlet is located in the middle of the reactor column section; the central light source includes a quartz light-transmitting lamp column and a mercury lamp, and is located at the center of the swirling photocatalytic reactor and connected to the top of the reactor; the bottom outlet is connected to the bottom of the reactor cone section; the center lines of the anti-vortex baffle, the central light source, and the bottom outlet coincide.

[0022] The reactor column diameter D2:column height H2 ratio is 1:1, and the reactor cone angle is... The tangential inlet diameter is 60°~120°. 21 Bottom outlet diameter D 22 The ratio is 1:2.

[0023] In another preferred embodiment, the cyclone gas-liquid-solid three-phase separator includes: a tangential inlet, a gas-liquid separation section, a helical guide vane, and a solid-liquid separation section; wherein, the gas-liquid separation section includes a columnar section, a central inner cone, a gas phase outlet, and a liquid phase outlet connected to the top of the helical guide vane; the helical guide vane is located between the gas-liquid separation section and the solid-liquid separation section; the solid-liquid separation section includes a columnar section, a conical section, an overflow outlet located at the center of the helical guide vane, and a solid phase outlet, wherein the overflow outlet penetrates the gas-liquid separation section and extends along the side of the liquid phase outlet of the gas-liquid separation section.

[0024] Among them, the diameter D3 of the cyclone gas-liquid-solid three-phase separator, the columnar height H3 of the gas-liquid separation section, and the columnar length H of the solid-liquid separation section are... 31 The ratio D3:H3:H 31 The ratio is 1:4:1, and the diameter D of the liquid phase outlet in the gas-liquid separation section is... 31 The overflow outlet diameter D of the solid-liquid separation section is 0.5D3. 32 The cone angle of the central inner cone is 0.3D3. The cone angle of the solid-liquid separation cone section is 16°. The range is 6° to 15°.

[0025] Furthermore, this disclosure provides a method for photocatalytic cyclone-enhanced hydrogen production from organic wastewater using the above-mentioned apparatus, the method comprising the following steps:

[0026] (a) Mixing of catalyst and wastewater: Wastewater entering the cyclone mixer tangentially and catalyst concentrate flowing out of the catalyst distributor of the cyclone mixer are initially mixed under the action of the cyclone field; then the initially mixed solution enters the Venturi mixing section of the cyclone mixer to achieve uniform mixing of wastewater and catalyst particles and obtain fully mixed material;

[0027] (b) Hydrogen production by cyclone-enhanced photocatalytic wastewater decomposition: The fully mixed material obtained in step (a) is fed into a cyclone photocatalytic reactor, and the wastewater photocatalytic reaction is excited by a central light source to decompose the organic wastewater to obtain hydrogen.

[0028] (c) Gas-liquid-solid three-phase separation: The hydrogen obtained in step (b) and the wastewater containing the mixed catalyst are fed into a cyclone gas-liquid-solid three-phase separator. Gas-liquid separation is completed in the middle of the separator. The gas is discharged from the gas phase outlet, and the liquid and catalyst enter the lower solid-liquid separation section. In the solid-liquid separation section, under the action of the spiral guide vanes, the density difference between the catalyst and the liquid is used to separate the catalyst particles from the liquid.

[0029] (d) Multi-stage treatment and reflux: The catalyst separated by the gas-liquid-solid three-phase separator is returned to step (a). Part of the treated liquid phase discharged from the separator is returned to step (a), and the other part enters the next stage reaction unit to repeat step (ad) until the treated water quality meets the standards.

[0030] (e) Hydrogen purification and collection: The gaseous products separated in the gas-liquid-solid three-phase separator are introduced from the bottom of the carbon dioxide absorption tower. After absorption and purification by the carbon dioxide absorption tower, pure hydrogen products are obtained.

[0031] Beneficial effects:

[0032] (1) By adopting a swirling photocatalytic reactor, the photocatalytic hydrogen production reaction of wastewater is enhanced from three aspects: reducing the activation energy of the photocatalytic hydrogen production reaction of wastewater by tensile and compressive stress and strain, breaking up liquid microparticles by turbulence to improve the mass transfer rate, promoting gas removal, and enhancing the active sites of the catalyst. This significantly improves the rate of the photocatalytic hydrogen production reaction of wastewater.

[0033] (2) A complete wastewater photocatalytic hydrogen production process is formed by combining a cyclone mixer, a cyclone photocatalytic reactor and a cyclone gas-liquid-solid three-phase separator. This process achieves enhanced control of the entire process from wastewater mixing, catalytic reaction and product separation. While ensuring a high reaction rate, it minimizes catalyst waste and features low catalyst loss and low secondary pollution.

[0034] (3) A treatment unit consisting of a cyclone photocatalytic reactor, a cyclone gas-liquid-solid three-phase separator and a cyclone mixer is adopted. Through the two methods of multi-unit series connection and reflux ratio adjustment, the wastewater with a wide range of organic pollutant concentrations can be effectively purified and has high resistance to shock loads. Attached Figure Description

[0035] The accompanying drawings are provided to further illustrate this disclosure and constitute only a part of this specification to further explain this disclosure, and do not constitute a limitation thereof.

[0036] Figure 1 This is a schematic diagram of a process for photocatalytic cyclone-enhanced hydrogen production from organic wastewater according to a preferred embodiment of the present disclosure.

[0037] Figure 2 This is a schematic diagram of a cyclone mixer structure according to a preferred embodiment of the present disclosure.

[0038] Figure 3 This is a schematic diagram of a swirling photocatalytic reactor according to a preferred embodiment of the present disclosure.

[0039] Figure 4 This is a schematic diagram of a swirling gas-liquid-solid three-phase separator according to a preferred embodiment of the present disclosure.

[0040] Figure 5 This is a schematic diagram of the process for photocatalytic cyclone-enhanced hydrogen production from tertiary organic wastewater according to Example 1 of this application. Detailed Implementation

[0041] The endpoints and any values ​​of the ranges disclosed herein are not limited to the precise ranges or values, and these ranges or values ​​should be understood to include values ​​close to these ranges or values. For numerical ranges, the endpoint values ​​of the various ranges, the endpoint values ​​of the various ranges and individual point values, and individual point values ​​can be combined with each other to obtain one or more new numerical ranges, which should be considered as specifically disclosed herein.

[0042] To address the problems of low photocatalytic efficiency, poor effluent quality, and difficulty in separating catalyst from wastewater in existing technologies, this application adopts a complete wastewater photocatalytic hydrogen production process combining a cyclone mixer, a cyclone photocatalytic reactor, and a cyclone gas-liquid-solid three-phase separator. This process utilizes photocatalysis to decompose organic matter in wastewater while simultaneously producing hydrogen, and leverages the chemical energy in the wastewater to achieve resource recovery in the form of hydrogen gas. Organic pollutants in the water are oxidized into carbon dioxide and water, reducing the COD of the wastewater and achieving the goal of synergistic water purification and resource recovery. After the photocatalytic reaction, a mixed solution containing hydrogen and catalyst particles is obtained. This solution enters the cyclone gas-liquid-solid three-phase separator to complete the separation of the solid, liquid, and gas phases. The cyclone gas-liquid-solid three-phase separator adopts a design of degassing before solid removal, improving solid separation efficiency. Effective separation of catalyst particles minimizes catalyst waste and prevents catalyst from escaping into the water and causing secondary pollution. Furthermore, even with excessively high organic matter concentrations in the wastewater, the treatment liquid reflux ratio can be adjusted to change the wastewater retention time to ensure effluent quality, making it applicable to a wide range of water qualities.

[0043] The applicant discovered that the photocatalytic hydrogen production reaction from wastewater is a pseudo-first-order reaction, and the first-order reaction kinetics formula is as follows:

[0044]

[0045] In the formula, c A denoted as reactant concentration, k as rate constant, and t as reaction time.

[0046] Therefore, the reaction rate of a first-order reaction can be obtained as a function of the reactant concentration c. A The square root of the reaction rate is inversely proportional to the concentration of the reaction solution, meaning the reaction rate is significantly affected by the concentration of the solution. Ensuring a uniform concentration distribution in the reaction solution is one of the main methods to maximize the rate of a first-order reaction. The principle of homogeneous mixing utilizes turbulence to break the fluid into micro-clusters, the size of which depends on the degree of turbulence. Intense turbulence reduces the size of these micro-clusters, and the smaller the micro-clusters, the faster the process of achieving molecular-scale homogeneity through molecular diffusion. In a hydrocyclone, the swirling flow field exhibits high turbulence, which can minimize the size of the micro-clusters, resulting in a uniform concentration distribution in the reaction solution and thus increasing the reaction rate.

[0047] In the photocatalytic hydrogen production process from wastewater, the generated hydrogen gas adheres to the active sites of the catalyst, reducing the effective contact area between the catalyst and the reaction solution. The mass transfer rate between the hydrogen gas generated on the catalyst surface and the solution is a crucial factor limiting the reaction rate; removing the adhered hydrogen gas will facilitate the photocatalytic reaction. In a hydrocyclone, the high-speed flow of liquid around the center of the hydrocyclone creates a negative pressure zone at the center of the swirling field, as described by Henry's Law.

[0048]

[0049] in The equilibrium partial pressure of the solute in the gas phase, in kPa;

[0050] Mole fraction of solute in the liquid phase;

[0051] E Henry coefficient, kPa.

[0052] According to Henry's Law, a negative pressure zone reduces the equilibrium partial pressure of hydrogen gas, causing hydrogen in the solution to precipitate and coalesce in the form of small bubbles within the negative pressure zone. This process effectively reduces the hydrogen concentration *c* in the solution. Furthermore, since hydrogen is a sparingly soluble gas, the hydrogen mass transfer rate is controlled by the liquid film, according to the absorption rate equation:

[0053]

[0054] In the formula, —Overall liquid phase absorption coefficient, kmol / (m 2 ·s·kmol / m 3 );

[0055] N A —Liquid film absorption rate, kmol / (m2 ·s)

[0056] c — The mass concentration of hydrogen at the phase interface, kmol / m 3 ,

[0057] c—Hydrogen concentration in the solution, kmol / m³ 3 .

[0058] Reducing the hydrogen concentration c in the solution can accelerate the liquid absorption rate of hydrogen generated on the catalyst surface, while preventing hydrogen from precipitating on the catalyst particle surface and affecting the reaction rate of photocatalytic hydrogen production from wastewater.

[0059] Tensile and compressive strain can effectively lower the activation energy of chemical reactions by altering the atomic structure and electronic properties of materials, thus playing a crucial role in enhancing the catalytic performance of catalysts. The principles of strain are mainly reflected in the following aspects:

[0060] First, lattice stress affects the electronic structure. When a material is stretched or compressed, the interatomic spacing in the lattice changes. This change affects the electronic band structure of the material, thereby altering the adsorption behavior of reactants on the catalyst surface. Tensile strain typically increases the interatomic spacing, adjusts the electronic structure, and makes the active sites on the surface more conducive to the binding and dissociation of reactants, thus lowering the activation energy of the reaction.

[0061] Secondly, the relationship between strain, adsorption energy, and reaction can be studied in depth through theoretical simulations. Density functional theory (DFT) simulations show that tensile or compressive strain directly affects the adsorption energy of reactants by altering the electronic states of the catalyst surface, thereby regulating the activation energy of the chemical reaction. In the electrocatalytic processes of the oxygen reduction reaction (ORR) and the hydrogen evolution reaction (HER), applying strain can significantly improve catalyst performance. This method of regulating catalyst performance through strain is particularly suitable for alloy and core-shell structured catalysts, where strain can alter the interactions between different metal elements, enhancing the overall catalytic effect.

[0062] Furthermore, the combined effects of geometric strain and energy factors in strain regulation are also crucial. Taking core-shell nanoparticles as an example, both geometric strain and the electronic state of the core material directly influence the catalyst's activity. When strain is applied to a core-shell catalyst, the lattice constant of the shell metal changes, thereby altering its electronic band structure. This change includes both structural deformation caused by geometric strain and energy regulation of the shell's electronic state by the core material. By rationally selecting the core material and adjusting the shell thickness, the strain effect can be optimized, thereby regulating the activation energy and catalytic performance of the reaction.

[0063] In summary, tensile and compressive strains can significantly improve catalyst performance by altering the electronic structure and geometry of the catalyst material, thereby reducing the activation energy of the chemical reaction. In a swirling flow field, the presence of a three-dimensional high-speed swirling turbulent field causes the catalyst particles within it to be continuously subjected to varying tensile and compressive strains, thus reducing the activation energy of the photocatalytic hydrogen production reaction from wastewater.

[0064] In a first aspect of this disclosure, a method for photocatalytic cyclone-enhanced hydrogen production from organic wastewater is provided, the method comprising the following steps:

[0065] (A) Shearing and oscillating mixing of catalyst and wastewater: The catalyst particles and organic wastewater are initially sheared and mixed using a swirling flow field, and then the initial mixture is oscillated and mixed using the Venturi effect to obtain a uniformly dispersed mixed solution of catalyst.

[0066] (B) Wastewater swirling oscillation photocatalytic hydrogen production: The mixed solution is regulated to undergo three-dimensional rotating turbulent motion to form a swirling field, and a light source is introduced at the center of the swirling field to produce hydrogen through photolysis; the high turbulence of the fluid in the swirling field breaks up the liquid micro-particles in the solution, thereby improving the mass transfer rate of the reaction; at the same time, the swirling excites micro-interface oscillations on the catalyst surface; this reduces the activation energy of the wastewater photocatalytic reaction, increases the reaction rate of photocatalytic hydrogen production, and yields a three-phase mixed solution containing catalyst particles, hydrogen, and wastewater;

[0067] (C) Gas-liquid-solid three-phase separation and catalyst recycling: Centrifugation is used to separate the catalyst particles, hydrogen and wastewater by utilizing the density difference between the three to obtain the catalyst particle solid phase, the hydrogen-containing gas phase and the treated liquid phase. The catalyst is recycled back to the treatment process in step (A).

[0068] In this disclosure, the COD (chemical oxygen demand) content of the organic wastewater is 500-6000 mg / L.

[0069] In this disclosure, the catalyst is granular with a particle size of 50-600 μm, and includes COFs (covalent organic framework materials) or TiO2, with a Pt content of 0.5-12% of the catalyst mass.

[0070] In this disclosure, in step (A), since cyclone mixing relies on the kinetic energy of the fluid for mixing, the process control precision is poor, and the turbulent characteristics of the flow make it difficult to accurately control the mixing effect. In the case of a Venturi mixer without premixing, the energy distribution in the fluid will be uneven due to the inertia of the solid particles and the rapid change of the flow velocity in the mixer. The solid particles cannot effectively respond to these energy changes, making it difficult to achieve uniform dispersion and mixing. By using a cyclone mixer to premix the catalyst and wastewater, the catalyst and wastewater mixed microparticles are premixed into millimeter-sized microparticles, and then finely mixed using a Venturi mixer, a uniformly distributed catalyst-wastewater system can be obtained.

[0071] In a second aspect of this disclosure, an apparatus for photocatalytic cyclone-enhanced hydrogen production from organic wastewater is provided, the apparatus comprising:

[0072] The reactor consists of a cyclone mixer, a cyclone photocatalytic reactor, a water pump, a cyclone gas-liquid-solid three-phase separator, and a carbon dioxide absorption tower. The cyclone mixer, cyclone photocatalytic reactor, and cyclone gas-liquid-solid three-phase separator constitute the primary reaction unit. The outlet of the mixed solution from the cyclone mixer is connected to the double-tangential cyclone inlet of the cyclone photocatalytic reactor. After photocatalytic hydrogen production is completed, the three-phase mixed solution of wastewater, catalyst, and hydrogen is discharged from the bottom outlet of the cyclone photocatalytic reactor. After being pressurized by the water pump, it is discharged from the water pump outlet and then passes through the cyclone separator connected to the water pump outlet. The catalyst particles enter the cyclone gas-liquid-solid three-phase separator through the tangential inlet. After gas-liquid-solid separation is achieved by the cyclone gas-liquid-solid three-phase separator, the solid phase is discharged from the solid phase outlet of the cyclone gas-liquid-solid three-phase separator and returned to the cyclone mixer through the catalyst inlet of the mixer connected to the solid phase outlet. The treated liquid phase is discharged from the liquid phase outlet of the cyclone gas-liquid-solid three-phase separator and returned to the cyclone mixer through the liquid phase tangential inlet of the mixer connected to the liquid phase outlet. The hydrogen-containing gas phase is discharged from the gas phase outlet of the cyclone gas-liquid-solid three-phase separator and enters the carbon dioxide absorption tower.

[0073] In this disclosure, the number of reaction stages increases according to the increase in COD content of the treated wastewater, typically ranging from 1 to 4 stages; the reflux ratio of the treated liquid phase is 2:1 to 4:1.

[0074] In this disclosure, when the COD content is 500 mg / L to less than 1000 mg / L, a single-stage treatment is used; when the COD content is 1000 mg / L to less than 3000 mg / L, a two-stage series treatment is used; when the COD content is 3000 mg / L to less than 4500 mg / L, a three-stage series treatment is used; and when the COD content is 4500-6000 mg / L, a four-stage series treatment is used.

[0075] In this disclosure, the cyclone mixer includes: a tangential liquid phase inlet, a mixer column, a catalyst distributor, a Venturi mixing section, a mixed solution outlet, and a catalyst inlet; wherein, the tangential liquid phase inlet is located at the bottom of the mixer column, and the catalyst distributor is coaxially disposed at the bottom of the mixer column; the Venturi mixing section consists of two spherical shells with decreasing diameters, located above the mixer column, and connected to the mixed solution outlet.

[0076] In this disclosure, the ratio of the diameter D1 of the cyclone mixer to the height H1 of the mixer column is 1:2, and the diameter D of the catalyst distributor is... 12 The ratio is 0.5D1, and the ratio of the spherical shell radius R1:R2 of the Venturi mixed segment is 2:1.

[0077] In this disclosure, the diameter D1 of the cyclone mixer is 200-800 mm.

[0078] In this disclosure, the radius R1 of the spherical shell of the Venturi hybrid segment is 1 / 3D1-1 / 2D1.

[0079] In this disclosure, the swirling photocatalytic reactor includes: a reactor column section, a reactor cone section, a dual-tangential swirling inlet, a central light source, an anti-vortex baffle, and a bottom outlet; wherein, the dual-tangential swirling inlet is located in the middle of the reactor column section; the central light source includes a quartz light-transmitting lamp column and a mercury lamp, and is located at the center of the swirling photocatalytic reactor and connected to the top of the reactor; the bottom outlet is connected to the bottom of the reactor cone section; the center lines of the anti-vortex baffle, the central light source, and the bottom outlet coincide.

[0080] In this disclosure, the reactor column diameter D2:column height H2 ratio is 1:1, and the reactor cone angle is... The tangential inlet diameter is 60°~120°. 21 Bottom outlet diameter D 22 The ratio is 1:2.

[0081] In this disclosure, the reactor column diameter D2 is 300-3000 mm.

[0082] In this disclosure, the tangential inlet diameter D 21 It is 0.05D2.

[0083] In this disclosure, the cyclone gas-liquid-solid three-phase separator includes: a tangential inlet, a gas-liquid separation section, a helical guide vane, and a solid-liquid separation section; wherein, the gas-liquid separation section includes a gas-liquid separation section column, a central inner cone, a gas phase outlet, and a liquid phase outlet connected to the top of the helical guide vane; the helical guide vane is located between the gas-liquid separation section and the solid-liquid separation section; the solid-liquid separation section includes a solid-liquid separation section column, a solid-liquid separation section cone, an overflow outlet located at the center of the helical guide vane, and a solid phase outlet, wherein the overflow outlet penetrates the gas-liquid separation section and extends along the side of the liquid phase outlet of the gas-liquid separation section.

[0084] In this disclosure, the diameter D3 of the cyclone gas-liquid-solid three-phase separator, the columnar height H3 of the gas-liquid separation section, and the columnar length H of the solid-liquid separation section are specified. 31 The ratio D3:H3:H 31 The ratio is 1:4:1, and the diameter D of the liquid phase outlet in the gas-liquid separation section is... 31 The overflow outlet diameter D of the solid-liquid separation section is 0.5D3. 32 The cone angle of the central inner cone is 0.3D3. The cone angle of the solid-liquid separation cone section is 16°. The range is 6° to 15°.

[0085] In this disclosure, the diameter D3 of the cyclone gas-liquid-solid three-phase separator is 50-500 mm.

[0086] In a third aspect of this disclosure, a method for photocatalytic cyclone-enhanced hydrogen production from organic wastewater using the above-described apparatus is provided, the method comprising the following steps:

[0087] (a) Mixing of catalyst and wastewater: Wastewater entering the cyclone mixer tangentially and catalyst concentrate flowing out of the catalyst distributor of the cyclone mixer are initially mixed under the action of the cyclone field; then the initially mixed solution enters the Venturi mixing section of the cyclone mixer. In the Venturi mixing section, the flow rate of the mixed solution increases rapidly and the turbulence in the fluid increases, so as to achieve uniform mixing of wastewater and catalyst particles and obtain fully mixed material;

[0088] (b) Cyclone-enhanced photocatalytic wastewater decomposition for hydrogen production: The thoroughly mixed material obtained in step (a) is fed into a cyclone photocatalytic reactor, and the wastewater photocatalytic reaction is excited by a central light source to decompose the organic wastewater to obtain hydrogen. In this process, the high turbulence of the flow field in the cyclone field is utilized to enhance the surface renewal rate of the wastewater and catalyst particles, break up the liquid micro-clusters of the fluid, and improve the photocatalytic hydrogen production rate. At the same time, the surface of the catalyst particles is subjected to continuously changing tensile and compressive strains in the cyclone field. The surface tensile and compressive strains will reduce the activation energy required for the catalyst reaction, thereby increasing the photocatalytic hydrogen production rate of the wastewater.

[0089] (c) Gas-liquid-solid three-phase separation: The hydrogen obtained in step (b) and the wastewater containing the mixed catalyst are fed into a cyclone gas-liquid-solid three-phase separator. Gas-liquid separation is completed in the middle of the separator. The gas is discharged from the gas phase outlet, and the liquid and catalyst enter the lower solid-liquid separation section. In the solid-liquid separation section, the flow rate of the mixed material in the separator is increased under the action of the spiral guide vanes, which enhances the effect of the cyclone flow field. The density difference between the catalyst and the liquid is used to separate the catalyst particles from the liquid.

[0090] (d) Multi-stage treatment and reflux: The catalyst separated by the gas-liquid-solid three-phase separator is returned to step (a). Part of the treated liquid phase discharged from the separator is returned to step (a), while the other part enters the next stage reaction unit to repeat step (ad) until the treated water quality meets the standards; and

[0091] (e) Hydrogen purification and collection: The gaseous products separated in the gas-liquid-solid three-phase separator are introduced from the bottom of the carbon dioxide absorption tower. After absorption and purification by the carbon dioxide absorption tower, pure hydrogen products are obtained.

[0092] In this disclosure, a multi-stage photocatalytic cyclone-enhanced hydrogen production device for organic wastewater can be connected in series according to the different COD contents and organic matter decomposition difficulties in the actual water body, so as to maintain high treatment efficiency while taking into account the requirements of water quality. By connecting the multi-stage photocatalytic cyclone-enhanced hydrogen production reaction units for organic wastewater in series, the COD content in the treated wastewater can be reduced step by step, so as to obtain better water quality treatment effect and improve hydrogen production efficiency. The generated gas is concentrated and passed into a carbon dioxide absorption tower to absorb carbon dioxide and obtain pure hydrogen.

[0093] Please refer to the attached diagram below.

[0094] Figure 1 This is a schematic diagram of a process for photocatalytic cyclone-enhanced hydrogen production from organic wastewater according to a preferred embodiment of this disclosure. Figure 1As shown, the cyclone mixer 1, the cyclone photocatalytic reactor 2, and the cyclone gas-liquid-solid three-phase separator 4 constitute the primary reaction unit. Organic wastewater enters the cyclone mixer through the liquid-phase tangential inlet, where the catalyst and wastewater undergo shear-oscillation mixing to obtain a uniformly dispersed catalyst solution. Once the catalyst concentration reaches the target concentration, catalyst injection is stopped, and the catalyst circulates within the reaction unit. The mixed solution exits from the cyclone mixer's outlet and enters the cyclone photocatalytic reactor through the dual-tangential cyclone inlet, where it undergoes cyclone oscillation photocatalytic hydrogen production, yielding a three-phase mixed solution containing catalyst particles, wastewater, and hydrogen. The three-phase mixed solution exits from the bottom outlet of the cyclone photocatalytic reactor, is pressurized by water pump 3, and then discharged from the water pump outlet. The catalyst particles enter the cyclone gas-liquid-solid three-phase separator through the tangential inlet for gas-liquid-solid three-phase separation, obtaining a catalyst particle solid phase, a hydrogen-containing gas phase, and a treated liquid phase. The catalyst particle solid phase is discharged from the solid phase outlet of the cyclone gas-liquid-solid three-phase separator and returned to the cyclone mixer via the catalyst inlet of the mixer connected to the solid phase outlet. The treated liquid phase is discharged from the liquid phase outlet of the cyclone gas-liquid-solid three-phase separator, with a portion flowing back to the cyclone mixer via the liquid phase tangential inlet of the mixer connected to the liquid phase outlet, and the other portion being discharged as purified water. The hydrogen-containing gas phase is discharged from the gas phase outlet of the cyclone gas-liquid-solid three-phase separator and enters the carbon dioxide absorption tower 5 (in which lean absorbent is added). The purified hydrogen is discharged from the top of the carbon dioxide absorption tower, and the rich absorbent is discharged from the bottom of the carbon dioxide absorption tower.

[0095] Figure 2 This is a schematic diagram of a cyclone mixer structure according to a preferred embodiment of the present disclosure. Figure 2 As shown, the cyclone mixer includes: a tangential liquid phase inlet 11, a mixer column section 13, a catalyst distributor 12, a Venturi mixing section 14, a mixed solution outlet 15, and a catalyst inlet 16. The tangential liquid phase inlet 11 is located at the bottom of the mixer column section 13, and the catalyst distributor 12 is coaxially disposed at the bottom of the mixer column section 13. The Venturi mixing section 14 consists of two spherical shells with decreasing diameters, located above the mixer column section 13, and connected to the mixed solution outlet 15. The ratio of the diameter D1 of the cyclone mixer to the height H1 of the mixer column section is 1:2, and the diameter D1 of the catalyst distributor is... 12 The ratio of the spherical shell radius R1:R2 of the Venturi hybrid segment is 0.5D1, which is 2:1.

[0096] The catalyst concentrate is ejected from the catalyst distributor and initially mixed with the tangentially entering wastewater. The pre-mixed solution then enters the Venturi mixing section. Since swirling mixing relies on the kinetic energy of the fluid, process control precision is poor, and the turbulent flow characteristics make precise control of the mixing effect difficult. In the Venturi mixing section, without premixing, the inertia of the solid particles combined with rapid velocity changes in the mixer leads to uneven energy distribution in the fluid, making it difficult for the solid particles to effectively respond to these energy changes and achieve uniform dispersion and mixing. Premixing the catalyst and wastewater using a swirling mixer followed by fine mixing in the Venturi mixing section results in a uniformly distributed catalyst-wastewater system. During the Venturi mixing, the continuous change in the flow velocity of the mixed solution induces the Venturi effect, achieving uniform mixing of the wastewater and catalyst particles and obtaining a fully mixed material system.

[0097] Figure 3 This is a schematic diagram of a swirling photocatalytic reactor according to a preferred embodiment of the present disclosure. Figure 3 As shown, the swirling photocatalytic reactor includes: a reactor column section 21, a reactor cone section 22, a dual-tangential swirling inlet 23, a central light source 24, an anti-vortex baffle 25, and a bottom outlet 26; wherein, the dual-tangential swirling inlet 23 is located in the middle of the reactor column section 21; the central light source 24 includes a quartz light-transmitting lamp column 241 and a mercury lamp 242, and is located at the center of the swirling photocatalytic reactor and connected to the top of the reactor; the bottom outlet 26 is connected to the bottom of the reactor cone section 22; the center lines of the anti-vortex baffle 25, the central light source 24, and the bottom outlet 26 coincide; wherein, the ratio of the reactor column diameter D2 to the column height H2 is 1:1, and the cone angle of the reactor cone section is... The tangential inlet diameter is 60°~120°. 21 Bottom outlet diameter D 22 The ratio is 1:2;

[0098] The described swirling photocatalytic reactor utilizes the high turbulence within the swirling flow field to enhance the renewal rate of the liquid film on the surface of the catalyst particles and thus increase the photocatalytic hydrogen production rate by improving the mass transfer rate. Simultaneously, the catalyst particles are subjected to continuously varying tensile and compressive strains within the swirling flow field. These strains lower the activation energy required for the catalyst reaction, further increasing the photocatalytic hydrogen production rate.

[0099] Figure 4 This is a schematic diagram of a swirling gas-liquid-solid three-phase separator according to a preferred embodiment of this disclosure. Figure 4As shown, the cyclone gas-liquid-solid three-phase separator includes: a tangential inlet 41, a gas-liquid separation section 42, a helical guide vane 43, and a solid-liquid separation section 44; wherein, the gas-liquid separation section 42 includes a gas-liquid separation section column 421, a central inner cone 422, a gas phase outlet 423, and a liquid phase outlet 445 connected to the top of the helical guide vane 43; the helical guide vane 43 is located between the gas-liquid separation section 42 and the solid-liquid separation section 44; the solid-liquid separation section 44 includes a solid-liquid separation section column 441, a solid-liquid separation section cone 442, an overflow outlet 444 located at the center of the helical guide vane 43, and a solid phase outlet 443, wherein the overflow outlet 444 penetrates the gas-liquid separation section 42 and extends along the side of the liquid phase outlet 445 of the gas-liquid separation section 42; wherein, the diameter D3 of the cyclone gas-liquid-solid three-phase separator, the columnar height H3 of the gas-liquid separation section, and the columnar length H of the solid-liquid separation section are... 31 The ratio D3:H3:H 31 The ratio is 1:4:1, and the diameter D of the liquid phase outlet in the gas-liquid separation section is... 31 The overflow outlet diameter D of the solid-liquid separation section is 0.5D3. 32 The cone angle of the central inner cone is 0.3D3. The cone angle of the solid-liquid separation cone section is 16°. The range is 6° to 15°.

[0100] The cyclone gas-liquid-solid three-phase separator adopts a design of degassing first and then removing solids, which can effectively reduce the entrainment of catalyst particles by gas during the liquid-solid separation process and improve the solid separation efficiency. The spiral guide vanes installed between the gas-liquid separation zone and the liquid-solid separation zone can increase the flow velocity of the liquid out of the gas-liquid separation zone, thereby increasing the difference between the inertial force and centrifugal force on the particles in the liquid in the flow field, intensifying the migration of particles towards the wall in the conical section, and improving the liquid-solid separation effect.

[0101] Figure 5 This is a schematic diagram of the process for photocatalytic cyclone-enhanced hydrogen production from tertiary organic wastewater according to Example 1 of this application. Figure 5 As shown, the three-stage reaction units are connected in series, and each stage of the reaction unit consists of a cyclone mixer 1, a cyclone photocatalytic reactor 2, and a cyclone gas-liquid-solid three-phase separator 4;

[0102] First-stage reaction unit: Organic wastewater with a COD of 3000 mg / L enters the cyclone mixer through the liquid-phase tangential inlet. The catalyst and wastewater undergo shear-oscillation mixing to obtain a uniformly dispersed catalyst solution. This solution exits the cyclone mixer and enters the cyclone photocatalytic reactor through the dual tangential cyclone inlets. There, hydrogen is produced through cyclone oscillation photocatalysis, resulting in a three-phase solution containing catalyst particles, wastewater, and hydrogen. This three-phase solution exits the bottom outlet of the cyclone photocatalytic reactor, is pressurized by water pump 3, and then exits through the pump outlet. Finally, it passes through a cyclone gas-liquid-solid three-phase separator connected to the pump outlet. The gas enters a cyclone gas-liquid-solid three-phase separator for gas-liquid-solid three-phase separation, obtaining a catalyst particle solid phase, a hydrogen-containing gas phase, and a treated liquid phase. The catalyst particle solid phase is discharged from the solid phase outlet of the cyclone gas-liquid-solid three-phase separator and returned to the cyclone mixer via the catalyst inlet of the mixer connected to the solid phase outlet. Part of the treated liquid phase is discharged from the liquid phase outlet of the cyclone gas-liquid-solid three-phase separator and returned to the cyclone mixer via the liquid phase tangential inlet of the mixer connected to the liquid phase outlet. The other part (COD reduced to 1100 mg / L) is sent to the cyclone mixer of the secondary reaction unit. The hydrogen-containing gas phase is discharged from the gas phase outlet of the cyclone gas-liquid-solid three-phase separator and enters the carbon dioxide absorption tower 5 (in which lean absorbent is added).

[0103] Secondary Reaction Unit: Organic wastewater with a COD of 1100 mg / L enters the cyclone mixer through the liquid-phase tangential inlet. The catalyst and wastewater undergo shear-oscillation mixing to obtain a uniformly dispersed catalyst solution. This solution exits the cyclone mixer and enters the cyclone photocatalytic reactor through the dual-tangential cyclone inlet. There, hydrogen is produced through cyclone oscillation photocatalysis, resulting in a three-phase solution containing catalyst particles, wastewater, and hydrogen. This three-phase solution exits the bottom outlet of the cyclone photocatalytic reactor, is pressurized by water pump 3, and then discharged from the pump outlet. The solution then passes through a cyclone gas-liquid-solid three-phase reactor connected to the pump outlet. The catalyst particles enter the cyclone gas-liquid-solid three-phase separator through the tangential inlet of the separator for gas-liquid-solid three-phase separation, obtaining a catalyst particle solid phase, a hydrogen-containing gas phase, and a treated liquid phase. The catalyst particle solid phase is discharged from the solid phase outlet of the cyclone gas-liquid-solid three-phase separator and returned to the cyclone mixer via the catalyst inlet of the mixer connected to the solid phase outlet. Part of the treated liquid phase is discharged from the liquid phase outlet of the cyclone gas-liquid-solid three-phase separator and returned to the cyclone mixer via the liquid phase tangential inlet of the mixer connected to the liquid phase outlet. The other part (COD has been reduced to 500 mg / L) is sent to the cyclone mixer of the third-stage reaction unit. The hydrogen-containing gas phase is discharged from the gas phase outlet of the cyclone gas-liquid-solid three-phase separator and enters the carbon dioxide absorption tower 5.

[0104] In the tertiary reaction unit, organic wastewater with a COD of 500 mg / L enters the cyclone mixer through the tangential inlet of the liquid phase. The catalyst and wastewater undergo shear-oscillation mixing to obtain a uniformly dispersed catalyst solution. This solution exits the cyclone mixer and enters the cyclone photocatalytic reactor through the dual tangential cyclone inlets. There, hydrogen is produced through cyclone oscillation photocatalysis, yielding a three-phase solution containing catalyst particles, wastewater, and hydrogen. This three-phase solution exits the bottom outlet of the cyclone photocatalytic reactor, is pressurized by water pump 3, and then exits through the pump outlet. Finally, it enters the cyclone gas-liquid-solid three-phase separator through the tangential inlet connected to the pump outlet. The three-phase separator performs gas-liquid-solid three-phase separation to obtain catalyst particle solid phase, hydrogen-containing gas phase, and treated liquid phase. The catalyst particle solid phase is discharged from the solid phase outlet of the cyclone gas-liquid-solid three-phase separator and returned to the cyclone mixer via the catalyst inlet of the mixer connected to the solid phase outlet. Part of the treated liquid phase is discharged from the liquid phase outlet of the cyclone gas-liquid-solid three-phase separator and returned to the cyclone mixer via the liquid phase tangential inlet of the mixer connected to the liquid phase outlet. The other part (COD has been reduced to 50 mg / L) is discharged as purified water. The hydrogen-containing gas phase is discharged from the gas phase outlet of the cyclone gas-liquid-solid three-phase separator and enters the carbon dioxide absorption tower 5. The purified hydrogen is discharged from the top of the carbon dioxide absorption tower, and the rich absorbent is discharged from the bottom of the carbon dioxide absorption tower.

[0105] Example

[0106] The present invention is further illustrated below with reference to specific embodiments. However, it should be understood that these embodiments are for illustrative purposes only and do not constitute a limitation on the scope of the invention. Test methods in the following embodiments, unless otherwise specified, are generally performed under conventional conditions or as recommended by the manufacturer. Unless otherwise stated, all percentages and parts are by weight.

[0107] Example 1:

[0108] The method of this invention is used to treat organic wastewater in the methanol-to-olefins (MTO) process. The specific operation process and effects are described below:

[0109] 1. Material properties and related parameters

[0110] The main pollutants in the wastewater are phenol, cresol and hydroquinone, etc. The treatment capacity of the device is 3t / h, the COD content in the wastewater is 2500-3000mg / L, the catalyst used is COFs, the catalyst concentration in the reaction device is maintained at 0.05g / L, the catalyst particle size is 50-100μm, and the reaction temperature is room temperature.

[0111] 2. Process Flow

[0112] like Figure 5 As shown.

[0113] A three-stage photocatalytic cyclone-enhanced hydrogen production unit for organic wastewater is connected in series. The reflux ratio of the first-stage wastewater treatment is 2:1, the second-stage wastewater treatment is 2:1, and the third-stage wastewater treatment is 4:1. The diameters of the first-stage, second-stage, and third-stage cyclone photocatalytic reactors are 1500 mm, 1500 mm, and 3000 mm, respectively. The catalyst concentration in the treated wastewater is controlled at 500 mg / L.

[0114] 3. Main structural dimensions of the photocatalytic cyclone-enhanced hydrogen production unit from organic wastewater

[0115]

[0116] 4. Results Analysis

[0117] After 100 hours of continuous operation, the average effluent COD of the primary organic wastewater photocatalytic cyclone enhanced hydrogen production unit reached 1100 mg / L, the secondary organic wastewater photocatalytic cyclone enhanced hydrogen production unit reached 500 mg / L, and the tertiary organic wastewater photocatalytic cyclone enhanced hydrogen production unit reached 50 mg / L. The average residence time of the organic wastewater was 5 hours. The reaction unit treated the organic wastewater to meet discharge standards in a much shorter time than typical photocatalytic wastewater hydrogen production units. After the catalyst is mixed with the wastewater once, the catalyst is recycled within the reaction unit. The amount of catalyst carried away when the purified water is discharged is less than 10 ppm, the concentration of suspended solids (SS) in the water is less than 15 ppm, which is lower than the 20 ppm standard of the first stage in the "Integrated Wastewater Discharge Standard". The hydrogen production rate is 15.6 m³ / h.

[0118] Example 2:

[0119] According to the method of this invention, a laboratory-simulated organic wastewater treatment process with a capacity of 100 L / h was carried out. The specific operation process and effects are described below:

[0120] 1. Material properties and related parameters

[0121] The main pollutants in the wastewater are phenol, acetic acid, butanol, etc. The treatment capacity of the device is 100L / h, the COD content in the wastewater is 800mg / L, the catalyst used is COFs, the catalyst concentration in the reaction device is maintained at 0.1g / L, the catalyst particle size is 50-60μm, and the reaction temperature is room temperature.

[0122] 2. Process Flow

[0123] like Figure 1 As shown.

[0124] A single-stage organic wastewater photocatalytic cyclone enhanced hydrogen production device was adopted. The catalyst injection was stopped after the catalyst concentration in the reactor reached 1000 mg / L, and the reflux ratio was 3:1.

[0125] 3. Main structural dimensions of the photocatalytic cyclone-enhanced hydrogen production unit from organic wastewater

[0126]

[0127] 4. Results Analysis

[0128] After 10 hours of continuous operation and stabilization, the average COD of the effluent was 30 mg / L, and the average retention time of the organic wastewater was 1 hour. The time required for the reactor to treat the organic wastewater to meet discharge standards is significantly shorter than that of typical photocatalytic wastewater hydrogen production devices. After the catalyst is mixed with the wastewater once, it is recycled within the reactor. The amount of catalyst carried away by the purified water is less than 8 ppm, and the concentration of suspended solids (SS) in the water is less than 10 ppm, which is lower than the 20 ppm standard for Class I wastewater discharge in the "Integrated Wastewater Discharge Standard," resulting in minimal environmental impact. The hydrogen production rate is 1 m³ / h.

[0129] The embodiments listed above are merely preferred embodiments of this disclosure and are not intended to limit the scope of this disclosure. All equivalent changes and modifications made in accordance with the scope of this application should be considered within the technical scope of this disclosure.

[0130] All documents mentioned in this disclosure are incorporated herein by reference as if each document were individually incorporated herein by reference. Furthermore, it should be understood that after reading the foregoing teachings of this disclosure, those skilled in the art can make various alterations or modifications to this disclosure, and these equivalent forms also fall within the scope defined by the appended claims.

Claims

1. A method for photocatalytic cyclone-enhanced hydrogen production from organic wastewater, comprising the following steps: (A) Shearing and oscillating mixing of catalyst and wastewater: The catalyst particles and organic wastewater are initially sheared and mixed using a swirling flow field, and then the resulting initial mixture is oscillated and mixed using the Venturi effect to obtain a uniformly dispersed mixed solution of catalyst. (B) Wastewater vortex oscillation photocatalytic hydrogen production: The mixed solution obtained in step (A) is controlled to undergo three-dimensional rotating turbulent motion to form a vortex field, and a light source is introduced at the center of the vortex field for photocatalytic hydrogen production, thereby obtaining a three-phase mixed solution containing catalyst particles, wastewater, and hydrogen; and (C) Gas-liquid-solid three-phase separation and catalyst recycling: Centrifugation is used to separate the catalyst particles, hydrogen and wastewater by utilizing the density difference between the three to obtain the catalyst particle solid phase, the hydrogen-containing gas phase and the treated liquid phase. The catalyst particle solid phase is returned to the treatment process in step (A) for recycling.

2. The method as described in claim 1, characterized in that, In step (A), the COD content of the organic wastewater is 500-6000 mg / L; the particle size of the catalyst particles is 50-600 μm, and the catalyst includes COFs or TiO2.

3. A photocatalytic cyclone-enhanced hydrogen production device for organic wastewater, the device comprising: The reactor consists of a cyclone mixer (1), a cyclone photocatalytic reactor (2), a water pump (3), and a cyclone gas-liquid-solid three-phase separator (4). The cyclone mixer (1), the cyclone photocatalytic reactor (2), and the cyclone gas-liquid-solid three-phase separator (4) form a primary reaction unit. The mixed solution outlet (15) of the cyclone mixer is connected to the double tangential cyclone inlet (23) of the cyclone photocatalytic reactor. The three-phase mixed solution of wastewater, catalyst particles, and hydrogen obtained from the photolysis hydrogen production of the cyclone photocatalytic reactor is discharged from the bottom outlet (26) of the cyclone photocatalytic reactor. After being pressurized by the water pump (3), it is discharged from the outlet of the water pump (3) and then discharged through the water pump. (3) The tangential inlet (41) of the cyclone gas-liquid-solid three-phase separator connected to the outlet enters the cyclone gas-liquid-solid three-phase separator for gas-liquid-solid three-phase separation to obtain catalyst particle solid phase, hydrogen-containing gas phase and treated liquid phase. The catalyst particle solid phase is discharged from the solid phase outlet (443) of the cyclone gas-liquid-solid three-phase separator and returned to the cyclone mixer through the catalyst inlet (16) of the mixer connected to the solid phase outlet (443). The treated liquid phase is discharged from the liquid phase outlet (445) of the cyclone gas-liquid-solid three-phase separator and returned to the cyclone mixer (1) through the liquid phase tangential inlet (11) of the mixer connected to the liquid phase outlet (445). The cyclone mixer includes: a tangential liquid phase inlet (11), a mixer column (13), a catalyst distributor (12), a Venturi mixing section (14), a mixed solution outlet (15), and a catalyst inlet (16); wherein the tangential liquid phase inlet (11) is located at the bottom of the mixer column (13), and the catalyst distributor (12) is coaxially arranged at the bottom of the mixer column (13); the Venturi mixing section (14) is composed of two spherical shells with decreasing diameters, located above the mixer column (13), and connected to the mixed solution outlet (15).

4. The apparatus as described in claim 3, characterized in that, The device also includes a carbon dioxide absorption tower (5), wherein a hydrogen-containing gas phase is discharged from the gas phase outlet (423) of the cyclone gas-liquid-solid three-phase separator and enters the carbon dioxide absorption tower (5).

5. The apparatus as described in claim 3, characterized in that, The number of reaction stages increases with the increase of COD content in the organic wastewater, including 1-4 stages; the reflux ratio of the treated liquid phase is 2:1 to 4:

1.

6. The apparatus as claimed in claim 5, characterized in that, When the COD content is 500 mg / L to less than 1000 mg / L, a single-stage treatment is used; when the COD content is 1000 mg / L to less than 3000 mg / L, a two-stage series treatment is used; when the COD content is 3000 mg / L to less than 4500 mg / L, a three-stage series treatment is used; and when the COD content is 4500-6000 mg / L, a four-stage series treatment is used.

7. The apparatus as claimed in claim 3, characterized in that, The ratio of the diameter D1 of the cyclone mixer to the height H1 of the mixer column is 1:2, and the diameter D of the catalyst distributor is... 12 The ratio is 0.5D1, and the ratio of the spherical shell radius R1:R2 of the Venturi mixed segment is 2:

1.

8. The apparatus as claimed in claim 3, characterized in that, The swirling photocatalytic reactor includes: a reactor column section (21), a reactor cone section (22), a dual-tangential swirling inlet (23), a central light source (24), an anti-vortex baffle (25), and a bottom outlet (26); wherein, the dual-tangential swirling inlet (23) is located in the middle of the reactor column section (21); the central light source (24) includes a quartz light-transmitting lamp column (241) and a mercury lamp (242), which is located in the center of the swirling photocatalytic reactor and connected to the top of the reactor; the bottom outlet (26) is connected to the bottom of the reactor cone section (22); the center lines of the anti-vortex baffle (25), the central light source (24), and the bottom outlet (26) coincide; The reactor column diameter D2:column height H2 ratio is 1:1, and the reactor cone angle is... The tangential inlet diameter is 60°~120°. 21 Bottom outlet diameter D 22 The ratio is 1:

2.

9. The apparatus as claimed in claim 3, characterized in that, The swirling gas-liquid-solid three-phase separator includes: a tangential inlet (41), a gas-liquid separation section (42), a spiral guide vane (43), and a solid-liquid separation section (44); wherein, the gas-liquid separation section (42) includes a gas-liquid separation section column section (421), a central inner cone (422), a gas phase outlet (423), and a liquid phase outlet (445) connected to the top of the spiral guide vane (43); the spiral guide vane (43) is located between the gas-liquid separation section (42) and the solid-liquid separation section (44); the solid-liquid separation section (44) includes a solid-liquid separation section column section (441), a solid-liquid separation section cone section (442), an overflow outlet (444) located at the center of the spiral guide vane (43), and a solid phase outlet (443), wherein the overflow outlet (444) penetrates the gas-liquid separation section (42) and extends along the side of the liquid phase outlet (445) of the gas-liquid separation section (42). Among them, the diameter D3 of the cyclone gas-liquid-solid three-phase separator, the columnar height H3 of the gas-liquid separation section, and the columnar length H of the solid-liquid separation section are... 31 The ratio D3:H3:H 31 The ratio is 1:4:1, and the diameter D of the liquid phase outlet in the gas-liquid separation section is... 31 The overflow outlet diameter D of the solid-liquid separation section is 0.5D3. 32 The cone angle of the central inner cone is 0.3D3. The cone angle of the solid-liquid separation cone section is 16°. The range is 6° to 15°.

10. A method for photocatalytic cyclone-enhanced hydrogen production from organic wastewater using the apparatus of any one of claims 3-9, the method comprising the following steps: (a) Mixing of catalyst and wastewater: Wastewater entering the cyclone mixer tangentially and catalyst concentrate flowing out of the catalyst distributor of the cyclone mixer are initially mixed under the action of the cyclone field; then the initially mixed solution enters the Venturi mixing section of the cyclone mixer to achieve uniform mixing of wastewater and catalyst particles and obtain fully mixed material; (b) Hydrogen production by cyclone-enhanced photocatalytic wastewater decomposition: The fully mixed material obtained in step (a) is fed into a cyclone photocatalytic reactor, and the wastewater photocatalytic reaction is excited by a central light source to decompose the organic wastewater to obtain hydrogen. (c) Gas-liquid-solid three-phase separation: The hydrogen obtained in step (b) and the wastewater containing the mixed catalyst are fed into a cyclone gas-liquid-solid three-phase separator. Gas-liquid separation is completed in the middle of the separator. The gas is discharged from the gas phase outlet, and the liquid and catalyst enter the lower solid-liquid separation section. In the solid-liquid separation section, under the action of the spiral guide vanes, the density difference between the catalyst and the liquid is used to separate the catalyst particles from the liquid. (d) Multi-stage treatment and reflux: The catalyst separated by the gas-liquid-solid three-phase separator is returned to step (a). Part of the treated liquid phase discharged from the separator is returned to step (a), while the other part enters the next stage reaction unit to repeat step (ad) until the treated water quality meets the standards; and (e) Hydrogen purification and collection: The gaseous products separated in the gas-liquid-solid three-phase separator are introduced from the bottom of the carbon dioxide absorption tower. After absorption and purification by the carbon dioxide absorption tower, pure hydrogen products are obtained.

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