Method for treating benzotriazole wastewater by light synergic fixed bed catalytic oxidation

Abstract

This invention relates to the field of wastewater treatment technology, specifically to a method for photocatalytic oxidation treatment of benzotriazole wastewater using a fixed bed, comprising adsorption, desorption, photocatalytic oxidation, dilution and cooling, and condensation separation steps. The photocatalytic oxidation system used in this method includes a reaction unit, a rapid cooling and dilution unit, and a gas-liquid separation unit connected in series. The reaction unit includes a reaction tube and a drive mechanism mounted on the reaction tube. Spherical shell-shaped beds are arranged at intervals within the reaction tube. The reaction unit in this method, by incorporating a synchronously rotating spherical shell-shaped bed structure and built-in ultraviolet lamps, forms dynamic forced mixing during the reaction process, enhancing the mass transfer process between the gas, liquid, and solid phases, increasing oxygen dispersion and interface renewal frequency, reducing blind spots, and improving light energy utilization and reaction rate. This method is suitable for the catalytic oxidation treatment of high-concentration, high-salinity, and recalcitrant organic wastewater.

Description

Technical Field

[0001] This invention relates to the field of wastewater treatment technology, specifically to a method for photosynergistic fixed-bed catalytic oxidation treatment of benzotriazole wastewater. Background Technology

[0002] Benzotriazole and its derivatives are widely used as highly efficient corrosion inhibitors and metal passivators in industrial cooling water, automotive antifreeze, and metalworking fluids. These substances are chemically stable, readily bioaccumulate, and possess potential toxicity. Conventional biochemical degradation methods are inefficient, making the treatment of industrial wastewater containing these pollutants difficult.

[0003] Currently, advanced oxidation processes, such as ozone oxidation and photocatalytic oxidation, are often used for the deep treatment of these recalcitrant organic compounds. Among them, photocatalytic oxidation technology has attracted much attention due to its mild reaction conditions, ability to utilize sunlight or artificial light sources, and ability to generate highly oxidizing hydroxyl radicals; while fixed-bed catalytic oxidation utilizes supported catalysts to provide a stable reaction interface, which can improve mass transfer efficiency.

[0004] However, existing technologies still face the following problems when processing high-concentration, high-salt benzotriazole concentrates containing triazole rings: Traditional treatment methods use ordinary photoreactors (such as flat plate and autoclave types), which have limited contact area between the light source and the fluid, resulting in low light energy utilization. At the same time, the mass transfer effect of gas-liquid-solid three-phase mixing is poor, affecting the reaction efficiency. Catalytic oxidation processes generate intermediate flocculants. Oxygen readily adsorbs or coats the surface of these flocculants in the form of bubbles, leading to aggregation and the formation of localized hyperoxygen environments. This increases the risk of combustion and explosion upon contact with combustible small-molecule organic matter, and also prevents this oxygen from effectively participating in the main catalytic oxidation reaction, thereby reducing oxidant utilization efficiency and reaction rate. Furthermore, the flocculants with attached bubbles can clog the pores of the catalyst bed, affecting fluid distribution. Summary of the Invention

[0005] The purpose of this invention is to provide a method for photo-coordinated fixed-bed catalytic oxidation treatment of benzotriazole wastewater, in order to solve the technical problems mentioned in the background art.

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

[0007] A method for photocatalytic fixed-bed catalytic oxidation treatment of benzotriazole wastewater includes the following steps: Adsorption: Adjust the pH of the influent to 5-7, and pass the wastewater through the adsorption tower at a rate of 3-10 BV / h. At least two adsorption towers should be operated in series, and the BTA concentration in the effluent should be monitored periodically. Desorption: After adsorption saturation, a 12-20% sodium hydroxide solution is used as the desorbent, and the solution is passed through at 50-70℃ to obtain a high-concentration benzotriazole sodium salt concentrate. Photocatalytic oxidation: The concentrated liquid is passed into a photo-coordinated fixed-bed catalytic oxidation treatment system, and oxygen is introduced at the same time. Under light conditions, the liquid is catalytically oxidized and decomposed to obtain a gas-liquid mixture after the reaction. The photo-coordinated fixed-bed catalytic oxidation treatment system includes a reaction unit, a rapid cooling and dilution unit, and a gas-liquid separation unit connected in series. Dilution and cooling: Nitrogen gas and the gas-liquid mixture after the reaction are passed into the rapid cooling and dilution unit for dilution and cooling; Condensation separation: Low-temperature mixed gas is introduced into the separation unit for condensation treatment. The condensed liquid enters the subsequent intermediate treatment unit for further treatment, and the non-condensable gas is discharged to the tail gas absorption tower for further treatment before being discharged. The reaction unit includes a reaction tube and a drive mechanism mounted on the reaction tube. Spherical shell-shaped beds are arranged at intervals inside the reaction tube. The drive mechanism is used to drive each spherical shell-shaped bed to rotate synchronously. Each spherical shell-shaped bed includes a shaft, an outer bed layer, and an inner bed layer. The inner bed layer and the outer bed layer are fixedly mounted on the outer wall of the shaft, and the outer bed layer is distributed around the inner bed layer.

[0008] Preferably, one end of the reaction tube has a feed inlet, and the other end is connected to a discharge pipe; several first frustum seats are fixed at intervals above the reaction tube, and second frustum seats are fixed at positions corresponding to the positions of the first frustum seats below the reaction tube; the shaft is hollow and transparent, and is rotatably mounted on the corresponding first and second frustum seats; each shaft is equipped with an ultraviolet lamp; the cavity formed between the outer bed and the inner bed is filled with a catalyst body; each second frustum seat is connected to an oxygen supply pipeline.

[0009] Preferably, both the outer and inner bed layers are spherical, with the inner bed layer having a smaller diameter than the outer bed layer; the outer bed layer diameter matches the inner diameter of the reaction tube; and pores are evenly distributed on both the outer and inner bed layers.

[0010] Preferably, one end of the shaft extends through to the top of the first truncated cone and is rotatably connected to the first truncated cone, and the other end of the shaft extends through to the bottom of the second truncated cone and is rotatably connected to the second truncated cone; an arched mounting bracket is fixed on the outer wall of the reaction tube at a position corresponding to the position of each first truncated cone, and the ultraviolet lamp is fixedly mounted on the arched mounting bracket accordingly; the ultraviolet lamp extends downward through to the corresponding shaft and is rotatably connected to the shaft.

[0011] Preferably, the second truncated cone base is provided with annular guide cavities distributed around the ultraviolet lamp tube; several air inlet channels are opened on the top wall of the annular guide cavities around the ultraviolet lamp tube, each air inlet channel extends vertically upward and is connected to the inside of the reaction tube; each air inlet channel is equipped with a one-way valve that only allows oxygen to flow upward into the reaction tube; the oxygen supply pipeline includes a main air inlet pipe and multiple connecting pipes, and adjacent annular guide cavities are connected by connecting pipes; one end of the main air inlet pipe is connected to the annular guide cavity closest to the feed inlet, and the other end is connected to the oxygen supply equipment.

[0012] Preferably, the drive mechanism includes a drive motor and a worm gear; the drive motor is fixed on the outer wall of the reaction tube, the worm gear is fixed on the output shaft of the drive motor, and the worm gear extends along the length of the reaction tube; a worm wheel is fixed at the bottom end of each shaft, and each worm wheel meshes with the worm gear.

[0013] Preferably, a number of arc-shaped baffles are fixed at intervals around the axis of the shaft on the outer wall, and each arc-shaped baffle extends radially along the inner bed layer; the outer walls of the arc-shaped baffles are fixed to the inner walls of the inner bed layer, and a flow divider cavity is formed between two adjacent arc-shaped baffles.

[0014] Preferably, a turbulent zone is formed between two adjacent outer beds inside the reaction tube; when the two adjacent spherical shell beds rotate synchronously, turbulence can be formed in the turbulent zone, which can wash away the oxygen bubbles adsorbed on the intermediate flocculent.

[0015] Preferably, the cross-sections of two adjacent arc-shaped partitions are in a figure-eight shape that gradually expands away from the ultraviolet lamp tube; the inner wall of the inner bed and the two sides of the arc-shaped partitions are coated with photocatalytic material.

[0016] Preferably, the reaction tube, the quenching and dilution unit, and the gas-liquid separation unit are connected in series in the material flow direction. The quenching and dilution unit is used to dilute the oxygen concentration and pre-cool the material, while the gas-liquid separation unit is used to condense and separate the gas and liquid phases. The quenching and dilution unit is a mixing tank, and the gas-liquid separation unit is a condenser. The inlet of the mixing tank is connected to the outlet pipe, and the top of the mixing tank is connected to an air inlet pipe, which is connected to a nitrogen supply device. The outlet of the mixing tank is connected to the feed end of the condenser through a conveying pipe. The outlet of the condenser is connected to the tail gas absorption tower, and the liquid outlet at the bottom of the condenser is connected to the neutralization treatment unit.

[0017] Compared with the prior art, the beneficial effects of the present invention are as follows.

[0018] The reaction unit used in this method features a synchronously rotating spherical bed structure, coupled with built-in ultraviolet lamps, which creates dynamic forced mixing during the reaction process. This enhances the mass transfer process between the gas, liquid, and solid phases, increases oxygen dispersion and interface renewal frequency, reduces blind spots in light exposure, and improves light energy utilization and reaction rate. It is suitable for the catalytic oxidation treatment of high-concentration, high-salinity, and recalcitrant organic wastewater.

[0019] The reaction unit used in this method forms a turbulent zone between adjacent spherical shell beds. By utilizing the fluid shearing and impact generated by the synchronous rotation of the spherical shell beds, oxygen bubbles adsorbed on the surface of intermediate flocculated materials can be stripped away, preventing them from agglomerating and forming a local high-oxygen environment, reducing the risk of system combustion and explosion, and improving the utilization efficiency of oxygen in the main reaction.

[0020] The reaction unit used in this method employs a hollow, transparent shaft as the mounting and protection carrier for the ultraviolet lamp tube, which also functions as a transmission device. This structure achieves physical isolation between the light source and the reaction liquid, ensuring electrical safety and the lifespan of the light source. Furthermore, the shaft drives the outer and inner bed layers of the external load to rotate synchronously, simplifying the transmission layout and improving the system's structural compactness and operational stability.

[0021] The reaction unit used in this method has an arc-shaped baffle inside the spherical bed to form multiple flow channels. During the rotation of the bed, the inlet and outlet flow directions are constantly switched, which generates a periodic backflushing effect on the pores, preventing the pores from being blocked by the accumulation of dirt and flocculation, maintaining the smooth flow of fluid, and ensuring that the reaction efficiency does not decrease during long-term operation. Attached Figure Description

[0022] Figure 1 This is a flowchart illustrating the steps of this processing method; Figure 2 This is a schematic diagram of the overall structure of the processing system used in this processing method; Figure 3 This is one of the schematic diagrams of a partial external structure of the reaction tube in this invention; Figure 4 for Figure 3 Enlarged schematic diagram of the structure at point A in the middle; Figure 5 This is the second schematic diagram of a partial external structure of the reaction tube in this invention; Figure 6 This is a schematic diagram of a partial internal structure of the reaction tube in this invention; Figure 7 This is a schematic diagram of the drive mechanism structure in this invention; Figure 8 for Figure 7 Enlarged schematic diagram of the structure at point B; Figure 9 This is a schematic diagram of the structure of a spherical shell-shaped bed. Figure 10 for Figure 9 Enlarged schematic diagram of the structure at point C; Figure 11 This is a schematic diagram of a partial internal structure of a spherical shell-shaped bed. Figure 12 This is a schematic diagram of the flow structure in the turbulent region; Figure 13 This is a schematic diagram of the structural configuration of the mixing tank and condenser separator in this invention.

[0023] In the diagram: 01, Turbulent flow zone; 1, Reaction tube; 101, Feed inlet; 102, Discharge pipe; 103, Cover; 11, First frustum; 12, Second frustum; 121, Annular guide cavity; 122, Air inlet channel; 123, One-way valve; 124, Connecting pipe; 125, Main air inlet pipe; 2, Shaft; 21, Outer bed; 211, Agitator blade; 22, Inner bed; 23, Jacket cavity; 24, Catalyst body; 3, Ultraviolet lamp; 31, Arched mounting bracket; 4, Drive mechanism; 41, Drive motor; 411, Fixed base; 42, Worm gear; 421, Bracket; 43, Worm wheel; 5, Arc-shaped baffle; 51, Diverter cavity; 6, Mixing tank; 61, Air inlet pipe; 62, Conveying pipe; 7, Condenser separator; 71, Feed end; 72, Air outlet end; 73, Liquid outlet end. Detailed Implementation

[0024] The embodiments of the present invention will now be described with reference to the accompanying drawings.

[0025] In the description of the embodiments of the present invention, it should be noted that, unless otherwise explicitly specified and limited, the terms "connection" and "installation" should be interpreted broadly, wherein "fixed" means that the devices or elements are connected to each other and their relative positional relationship remains unchanged after connection. The directional terms mentioned in the embodiments of the present invention are only for reference to the directions in the accompanying drawings, and are intended to better and more clearly illustrate and understand the embodiments of the present invention. They are not intended to indicate or imply that the devices or elements referred to must have a specific orientation, or be constructed and operated in a specific orientation, and therefore should not be construed as limitations on the embodiments of the present invention. Example 1

[0026] Please see Figures 1-13 This invention provides a method for photo-coordinated fixed-bed catalytic oxidation treatment of benzotriazole wastewater. The method employs a photo-coordinated fixed-bed catalytic oxidation system and specifically includes the following steps: Adsorption: Adjust the pH of the influent to 5-7, and pass the wastewater through the adsorption tower at a rate of 3-10 BV / h. At least two adsorption towers should be operated in series, and the BTA concentration in the effluent should be monitored periodically. Desorption: After adsorption saturation, a 12-20% sodium hydroxide solution is used as the desorbent, and the solution is passed through at 50-70℃ to obtain a high-concentration benzotriazole sodium salt concentrate. Photocatalytic oxidation: The concentrated liquid is passed into a photo-coordinated fixed-bed catalytic oxidation treatment system, and oxygen is introduced at the same time. Under light conditions, the liquid is catalytically oxidized and decomposed to obtain a gas-liquid mixture after the reaction. The photo-coordinated fixed-bed catalytic oxidation treatment system includes a reaction unit, a rapid cooling and dilution unit, and a gas-liquid separation unit connected in series. Dilution and cooling: Nitrogen gas and the gas-liquid mixture after the reaction are passed into the rapid cooling and dilution unit for dilution and cooling; Condensation separation: The low-temperature mixed gas is introduced into the separation unit for condensation treatment. The condensed liquid enters the subsequent intermediate treatment unit for further treatment, and the non-condensable gas is discharged to the tail gas absorption tower for further treatment before being discharged. Example 2

[0027] Please see Figures 2-13 This embodiment is used to further explain the photo-coordinated fixed-bed catalytic oxidation treatment system in Embodiment 1. The working principle (usage method) of this treatment system also belongs to the content of the photo-coordinated fixed-bed catalytic oxidation treatment method for benzotriazole wastewater.

[0028] The reaction unit in this system includes a reaction tube 1 and a drive mechanism 4 mounted on the reaction tube 1. One end of the reaction tube 1 has a feed inlet 101, and the other end is connected to a discharge pipe 102. The feed inlet 101 is connected to the preceding process (such as the resin adsorption and alkaline desorption unit). The resin adsorption and alkaline desorption unit uses existing technology, and its specific structure and principle will not be described in detail. The resin adsorption unit is used to adsorb benzotriazole in the wastewater, while the alkaline desorption unit uses alkaline solution to desorb the adsorbed benzotriazole. After treatment by the resin adsorption and alkaline desorption unit, concentrated alkaline wastewater containing sodium benzotriazole can be obtained.

[0029] At least three spherical shell-shaped beds are arranged at intervals inside the reaction tube 1. Each spherical shell-shaped bed is rotatably installed. The drive mechanism 4 is used to drive each spherical shell-shaped bed to rotate synchronously, that is, the drive mechanism 4 can drive the spherical shell-shaped beds to rotate in the same direction at the same time. The spherical shell-shaped bed includes a shaft 2, an outer bed layer 21 and an inner bed layer 22. The reaction tube 1 is arranged horizontally. The top of the cross-sectional circumference of the reaction tube 1 is defined as the upper part of the reaction tube 1, and the bottom of the cross-sectional circumference is defined as the lower part of the reaction tube 1. Several first frustum seats 11 are fixed at intervals above the reaction tube 1. A second frustum seat 12 is fixed at the bottom of the reaction tube 1 at the position corresponding to each of the first frustum seats 11. The number of first frustum seats 11 and second frustum seats 12 is the same as the number of spherical shell-shaped beds.

[0030] The shaft 2 is hollow and transparent, and is installed on the first frustum 11 and the second frustum 12 at corresponding positions. One end of the shaft 2 extends through to the top of the first frustum 11 and is rotatably connected to the first frustum 11. The other end of the shaft 2 extends through to the bottom of the second frustum 12 and is rotatably connected to the second frustum 12. That is, the shaft 2 is rotatably connected to the first frustum 11 and the second frustum 12 at corresponding positions, so that the shaft 2 has the ability to rotate. At the same time, the outer wall of the shaft 2 is sealed with the first frustum 11 and the second frustum 12. The specific sealing method adopts the existing technology and will not be described in detail.

[0031] Each shaft 2 has an inner bed 22 and an outer bed 21 fixedly mounted on its outer wall. The outer bed 21 is distributed around the inner bed 22. A cavity 23 is formed between the outer bed 21 and the inner bed 22. The cavity 23 is filled with a catalyst body 24. Both the outer bed 21 and the inner bed 22 are spherical. The diameter of the inner bed 22 is smaller than that of the outer bed 21. The diameter of the outer bed 21 matches the inner diameter of the reaction tube 1. Pores are evenly distributed on the outer bed 21 and the inner bed 22 to allow the liquid and gas to pass through.

[0032] An arched mounting bracket 31 is fixed on the outer wall of the reaction tube 1 at a position corresponding to the position of each first truncated cone 11. An ultraviolet lamp 3 is fixedly installed on each arched mounting bracket 31, and the ultraviolet lamp 3 extends downward through to the corresponding shaft 2. The ultraviolet lamp 3 serves as a light source and is located at the center of the spherical shell-shaped bed, extending along the rotation axis of the spherical shell-shaped bed. At the same time, the ultraviolet lamp 3 is rotatably connected to the shaft 2 to ensure that the ultraviolet lamp 3 does not rotate with the shaft 2. The wiring terminal of the ultraviolet lamp 3 is exposed for easy power access. Meanwhile, by placing the ultraviolet lamp 3 inside the shaft 2, the shaft 2 can provide waterproof protection for the ultraviolet lamp 3, preventing the ultraviolet lamp 3 from directly contacting the liquid and gas.

[0033] Among them, the shaft 2 is made of polycarbonate or a special glass material with reinforcement treatment. This gives the shaft 2 excellent transparency (light transmittance of up to 90%), which facilitates the emission of light from the ultraviolet lamp tube 3. At the same time, it also has excellent impact resistance and rigidity, which enables the shaft 2 to withstand certain torsional loads and bending stresses, and can be used as a rotating drive shaft.

[0034] In addition, the active component of the catalyst body 24 is a composite of nano-TiO2 and a small amount of copper oxide. The particles of the catalyst body 24 are packed in a random manner, and the filling amount accounts for 90-95% of the total space of the cavity 23, so that a certain gap is left between the catalyst particles to facilitate the passage of liquid and gas.

[0035] In addition, each of the second frustum bases 12 is connected to an oxygen supply pipeline to supply oxygen to the reaction tube 1, specifically, as follows: Figure 10As shown, the second truncated cone pedestal 12 has an annular guide cavity 121 distributed around the ultraviolet lamp tube 3. Several air inlet channels 122 are formed on the top wall of the annular guide cavity 121 around the ultraviolet lamp tube 3. Each air inlet channel 122 extends vertically upwards and communicates with the interior of the reaction tube 1. Each air inlet channel 122 is equipped with a one-way valve 123 that only allows oxygen to flow upwards into the reaction tube 1. Figure 5 As shown, the oxygen supply pipeline includes an air inlet main pipe 125 and multiple connecting pipes 124. Adjacent annular guide chambers 121 are connected by connecting pipes 124. One end of the air inlet main pipe 125 is connected to the annular guide chamber 121 closest to the feed inlet 101, and the other end is connected to the oxygen supply equipment (using existing technology, not shown in the figure).

[0036] Oxygen is supplied to the main intake pipe 125 via external oxygen supply equipment and flow meter control. The oxygen first enters the annular guide cavity 121 closest to the feed inlet 101, and then enters the subsequent annular guide cavities 121 in sequence under the guidance of the subsequent connecting pipes 124. The oxygen in each annular guide cavity 121 flows into the reaction tube 1 through the one-way valve 123 in each air inlet channel 122 (the one-way valve 123 only allows oxygen to flow from the annular guide cavity 121 into the reaction tube 1 and prevents liquid and gas in the reaction tube 1 from flowing back into the annular guide cavity 121), thus realizing the supply of oxygen. Moreover, the annular guide cavity 121 and the air inlet channel 122 are distributed at multiple points to ensure uniform oxygen supply.

[0037] like Figure 10 As shown, several stirring blades 211 are fixed on the outer wall of each outer bed 21 near the second truncated cone 12. The stirring blades 211 are arranged in a ring around the axis of the shaft 2. When the ultraviolet lamp tube 3, the inner bed 22 and the outer bed 21 rotate as a whole, they can drive the stirring blades 211 to rotate synchronously around the axis of the ultraviolet lamp tube 3. This can stir the oxygen bubbles entering the reaction tube 1 from the one-way valve 123, expand the distribution range of oxygen bubbles in the reaction tube 1, and ensure that the oxygen bubbles are more evenly distributed in the reaction tube 1.

[0038] The working principle of this embodiment is as follows: Concentrated alkaline wastewater containing sodium benzotriazole from the preceding process is stably fed into the reaction tube 1 through the feed inlet 101 via a metering pump and a flow meter. At the same time, oxygen (purity > 99%) or a mixture of ozone and oxygen is introduced into the reaction tube 1 through each one-way valve 123. The concentrate and oxygen can be preheated by a preheater (not shown in the figure) before entering the reaction tube 1. The concentrate and oxygen bubbles flow from the inlet 101 to the outlet 102 in the reaction tube 1. The drive mechanism 4 drives the shafts 2, outer bed 21 and inner bed 22 at each position to rotate simultaneously. The concentrate and oxygen bubbles pass through the outer bed 21 and inner bed 22 at each position in sequence to form a gas-liquid two-phase mixture. The fluid flows in the tortuous pores, and the cross-section of the flow channel changes continuously, resulting in fluctuating flow velocity and generating local eddies and turbulence. The liquid flow and bubbles continuously impact the surface of the catalyst particles, causing deformation, rupture and aggregation. Large bubbles are divided into smaller microbubbles, increasing the gas-liquid mass transfer interface. At the same time, the liquid film is continuously formed, renewed and detached on the catalyst surface, so that the benzotriazole salt molecules dissolved in the liquid and the oxygen molecules transferred from the gas phase to the liquid phase can diffuse more effectively to the active sites on the surface of the catalyst particles. Ultraviolet light emitted by the ultraviolet lamp 3 passes through the shaft 2 and the reaction liquid, irradiating the surface of the catalytic particles and exciting the generation of photogenerated electrons and holes. Holes can directly oxidize organic matter or react with water to generate ·OH free radicals. At the same time, dissolved oxygen and introduced oxygen capture photogenerated electrons to generate superoxide free radicals, which are further converted into active species such as ·OH. Components such as CuO in the catalyst body 24 can activate oxygen under thermal conditions, providing another pathway for the generation of active oxygen species. The coupling of light and catalysis, combined with the strong mixing effect of the outer bed 21 and the inner bed 22, ensures that the reactants are in full contact with the strong oxidant, so that the benzene ring and triazole ring structure of benzotriazole are broken down into small molecules such as formic acid, acetic acid, oxalic acid, nitrate, carbon dioxide and water, thereby achieving the photocatalytic oxidation treatment of wastewater.

[0039] The outer bed 21 and inner bed 22 have a circular structure, which effectively reduces the dead zones in the irradiation range of the ultraviolet lamp 3. The outer bed 21 and inner bed 22 rotate continuously, forming a dynamic forced mixing effect, which can continuously shear and renew the static liquid film attached to the surface of the catalyst particles, continuously transporting fresh reactants to the active sites of the catalyst, while rapidly removing reaction products. This solves the problem of interfacial reaction stagnation caused by diffusion limitation in traditional fixed beds. At the same time, this mechanism can also enhance the mass transfer process of the gas, liquid and solid phases, promote oxygen dispersion, increase the frequency of reaction interface renewal, and enhance the uniformity of ultraviolet light irradiation on the catalyst surface, thereby improving the rate and treatment effect of photocatalytic oxidation reaction.

[0040] In addition, the continuous rotation of the outer bed 21 and the inner bed 22 generates turbulence, which can break the adsorption and encapsulation of oxygen bubbles by the intermediate flocculants, prevent them from agglomerating and forming a local high-oxygen environment, reduce the risk of combustion and explosion, and improve the utilization efficiency of oxygen.

[0041] like Figure 12As shown (solid arrows in the figure indicate the direction of fluid flow), since all the spherical shell-shaped beds rotate simultaneously in the same direction (the direction of rotation corresponds to the corresponding dashed arrows), a turbulent zone 01 can be formed between the two adjacent outer beds 21 in the reaction tube 1. When the two adjacent spherical shell-shaped beds rotate synchronously, a turbulent impact effect is formed at the turbulent zone 01, which can further dislodge the oxygen bubbles adsorbed on the intermediate flocculent, reduce excessive oxygen accumulation. In addition, turbulence can also enhance the heat transfer between fluids, avoid local overheating, and maintain a stable reaction temperature.

[0042] In addition, the outer surface of each shaft 2 is smooth. When the drive mechanism 4 drives each shaft 2 to rotate, the shaft 2 and the fluid continue to move relative to each other and form a centrifugal force, which effectively prevents dirt and flocculation from adsorbing and accumulating on the outer wall of the shaft 2, thereby preventing the outer wall of the shaft 2 from reducing the transmittance of ultraviolet light due to scaling and ensuring that the light conditions remain stable. Example 3

[0043] Please see Figure 7 and Figure 8 Based on Embodiment 2, this embodiment provides a detailed explanation of the drive mechanism 4, as follows: The drive mechanism 4 includes a drive motor 41 and a worm gear 42. A fixed seat 411 is fixed on the outer wall of the reaction tube 1. The drive motor 41 is fixed on the fixed seat 411. Two brackets 421 are fixed on the outer wall of the reaction tube 1. The worm gear 42 is rotatably mounted on the two brackets 421. At the same time, the worm gear 42 is fixedly connected to the output shaft of the drive motor 41. The worm gear 42 extends along the length of the reaction tube 1. A worm wheel 43 is fixed on the bottom end of each shaft 2. Each worm wheel 43 meshes with the worm gear 42.

[0044] When the drive motor 41 is working, its output shaft can drive the worm 42 to rotate. Under the meshing transmission action of the worm 42 and each worm wheel 43, the worm 42 can simultaneously drive each shaft 2 to rotate in the same direction, providing a stable drive for each spherical bed.

[0045] In addition, such as Figure 2 and Figure 3 A cover 103 is provided on the outer wall of the reaction tube 1, and the drive mechanism 4 is located inside the cover 103. The cover 103 serves as a protective measure to prevent accidental contact. Example 4

[0046] Please see Figure 11 The difference between this embodiment and embodiment 3 is as follows: Several arc-shaped baffles 5 are fixed at intervals around the axis of the shaft 2 on the outer wall. Each arc-shaped baffle 5 extends radially along the inner bed 22. The outer walls of the arc-shaped baffles 5 are fixed to the inner walls of the inner bed 22. A flow divider 51 is formed between two adjacent arc-shaped baffles 5.

[0047] The inner bed 22 is divided into multiple flow distribution chambers 51 by the arc-shaped baffle 5. During the continuous rotation of the spherical bed, the position of each flow distribution chamber 51 changes continuously around the axis of the shaft 2. The fluid enters the flow distribution chamber 51 and follows the movement, which achieves the effect of flow distribution, improves the overall efficiency and consistency of fluid treatment, and achieves continuous self-drive by rotation, reduces local flow resistance, facilitates stable operation of the system, and reduces structural load.

[0048] In addition, such as Figure 11 As shown, the fluid flows into the spherical shell bed according to the solid arrow and then flows out according to the dashed arrow. Some dirt and flocculation will block the pores along the flow direction of the fluid, affecting the normal flow of the fluid. The spherical shell bed continues to rotate, causing the orientation of the diversion chamber 51 to change continuously. The original inlet pores are switched to outlet pores, and the original outlet pores are switched to inlet pores. This mechanism plays a role in backflushing and unblocking the pores. Example 5

[0049] Please see Figure 11 The difference between this embodiment and embodiment 4 is that: The cross-sections of the two adjacent arc-shaped partitions 5 are in a figure-eight shape that gradually expands away from the ultraviolet lamp tube 3, so as to avoid forming a light-blocking structure and ensure that the light from the ultraviolet lamp tube 3 can effectively irradiate the two sides of the arc-shaped partition 5 and the inner wall of the inner bed layer 22, reducing the light dead angle.

[0050] In addition, the inner wall of the inner bed 22 and the two sides of the arc-shaped partition 5 are loaded with photocatalytic material coatings. The photocatalytic material coatings are nano-TiO2 coatings, g-C3N4 coatings, or a composite coating of the two, which increases the catalytic area. Even in areas without catalyst particles, the photocatalytic material coatings can provide photocatalytic activity. The photocatalytic material coatings, combined with the catalyst filled in the cavity 23, form a dual photocatalytic system that combines surface and volume, improving the utilization efficiency of the reaction space and the light energy utilization rate. Example 6

[0051] Please see Figure 2 and Figure 13 The difference between this embodiment and embodiment 5 is as follows: The reaction tube 1, the quench dilution unit, and the gas-liquid separation unit are connected in series in the material flow direction. The quench dilution unit is used to dilute the oxygen concentration and perform preliminary cooling of the material, while the gas-liquid separation unit is used to condense and separate the gas and liquid phases.

[0052] The rapid cooling and dilution unit uses a mixing tank 6, and the gas-liquid separation unit uses a condenser separator 7. The inlet of the mixing tank 6 is connected to the outlet pipe 102. The top of the mixing tank 6 is connected to an air inlet pipe 61, which is connected to a nitrogen supply device (using existing technology, not shown in the figure). The outlet of the mixing tank 6 is connected to the feed end 71 of the condenser separator 7 through a conveying pipe 62. The outlet end 72 of the condenser separator 7 is connected to a tail gas absorption tower (using existing technology, not shown in the figure). The liquid outlet end 73 at the bottom of the condenser separator 7 is connected to a neutralization treatment unit (using existing technology, not shown in the figure).

[0053] The gas-liquid mixture after reaction in reaction tube 1 flows out from discharge pipe 102 into mixing tank 6. At the same time, nitrogen is injected into mixing tank 6 through gas inlet pipe 61. The nitrogen and the aforementioned gas-liquid mixture are mixed evenly in mixing tank 6. On the one hand, the gas can be rapidly diluted to reduce the concentration of possible combustible organic vapors and oxygen to below the lower explosive limit, thereby improving safety. On the other hand, nitrogen can quickly reduce the temperature of the mixture, thereby providing a further explosion-proof effect.

[0054] After rapid cooling and dilution, the low-temperature mixed gas enters the condenser separator 7. Most of the water vapor and small molecule organic acid vapor produced by cracking in the mixed gas are condensed into liquid in the condenser separator 7 and discharged from the liquid outlet 73 at the bottom, and enter the subsequent neutralization or biochemical treatment unit; while the non-condensable gas is discharged from the gas outlet 72 to the tail gas absorption tower, and is discharged after further treatment.

[0055] The mixing tank 6 and the condenser separator 7 both adopt existing technologies, and their specific structures and working principles will not be described in detail here.

[0056] The control method of the present invention is automatic control through a controller. The control circuit of the controller can be implemented by simple programming by those skilled in the art. The power supply is also common knowledge in the art. Therefore, the present invention will not explain the control method and circuit connection in detail.

[0057] It will be apparent to those skilled in the art that the present invention is not limited to the details of the exemplary embodiments described above, and that the present invention can be implemented in other specific forms without departing from the spirit or essential characteristics of the present invention.

Claims

1. A method for photosynthetic fixed-bed catalytic oxidation treatment of benzotriazole wastewater, characterized in that, Includes the following steps: Adsorption: Adjust the pH of the influent to 5-7, and pass the wastewater through the adsorption tower at a rate of 3-10 BV / h. At least two adsorption towers should be operated in series, and the BTA concentration in the effluent should be monitored periodically. Desorption: After adsorption saturation, a 12-20% sodium hydroxide solution is used as the desorbent, and the solution is passed through at 50-70℃ to obtain a high-concentration benzotriazole sodium salt concentrate. Photocatalytic oxidation: The concentrated liquid is passed into a photocatalytic fixed bed catalytic oxidation treatment system and oxygen is introduced. Under light conditions, the liquid is catalytically oxidized and decomposed to obtain a gas-liquid mixture after the reaction. The processing system includes a reaction unit, a rapid cooling and dilution unit, and a gas-liquid separation unit connected in series. Dilution and cooling: Nitrogen gas and the gas-liquid mixture after the reaction are passed into the rapid cooling and dilution unit for dilution and cooling; Condensation separation: Low-temperature mixed gas is introduced into the separation unit for condensation separation. The reaction unit includes a reaction tube and a drive mechanism mounted on the reaction tube. Spherical shell-shaped beds are arranged at intervals inside the reaction tube, and a drive mechanism is used to drive each spherical shell-shaped bed to rotate synchronously. The spherical shell-shaped bed includes a shaft, an outer bed layer, and an inner bed layer. The inner bed layer and the outer bed layer are fixedly fitted on the outer wall of the shaft, and the outer bed layer is distributed around the inner bed layer. One end of the reaction tube has a feed inlet, and the other end is connected to a discharge pipe; Several first frustum seats are fixed at intervals above the reaction tube, and second frustum seats are fixed at positions corresponding to the positions of the first frustum seats below the reaction tube. The shaft is hollow and transparent, and is rotatably mounted on the first and second truncated circular bases at corresponding positions; Each shaft is equipped with an ultraviolet lamp. The cavity formed between the outer and inner beds is filled with a catalyst body; The catalyst body is a composite of nano-TiO2 and copper oxide. The catalyst particles are randomly packed, and the filling amount occupies 90-95% of the total space of the cavity. Each of the second truncated cone bases is connected to the oxygen supply pipeline; Both the outer and inner bed layers are spherical, with the inner bed layer having a smaller diameter than the outer bed layer. The outer bed diameter matches the inner diameter of the reaction tube; Pores are evenly distributed on both the outer and inner bed layers; One end of the shaft extends through to the top of the first frustum and is rotatably connected to the first frustum; the other end of the shaft extends through to the bottom of the second frustum and is rotatably connected to the second frustum. An arched mounting bracket is fixed on the outer wall of the reaction tube at a position corresponding to the position of each first truncated cone, and the ultraviolet lamp tube is fixedly installed on the arched mounting bracket accordingly; The ultraviolet lamp extends downwards through the corresponding shaft and is rotatably connected to the shaft. The second truncated cone is equipped with an annular flow guiding cavity distributed around the ultraviolet lamp tube; Several air inlet channels are provided around the ultraviolet lamp tube on the top wall of the annular flow guide cavity. Each air inlet channel extends vertically upward and is connected to the inside of the reaction tube. Each air inlet is equipped with a one-way valve that allows only oxygen to flow upward into the reaction tube; The oxygen supply pipeline includes a main intake pipe and multiple connecting pipes, with adjacent annular guide chambers connected by connecting pipes; One end of the main air intake pipe is connected to the annular guide cavity closest to the feed inlet, and the other end is connected to the oxygen supply equipment. The drive mechanism includes a drive motor and a worm gear; The drive motor is fixed to the outer wall of the reaction tube, and the worm is fixed to the output shaft of the drive motor, with the worm extending along the length of the reaction tube. Each shaft has a worm gear fixed at its bottom end, and each worm gear meshes with the worm. Several arc-shaped partitions are fixed at intervals around the axis of the shaft on its outer wall, and each arc-shaped partition extends radially along the inner bed layer; The outer walls of the arc-shaped partitions are all fixed to the inner walls of the inner bed, and a flow divider is formed between two adjacent arc-shaped partitions; A turbulent zone is formed inside the reaction tube between two adjacent outer beds; When two adjacent spherical shell-shaped beds rotate synchronously, turbulence can be generated in the turbulent zone, which can wash away the oxygen bubbles adsorbed on the intermediate flocculated material.

2. The method for photosynergistic fixed-bed catalytic oxidation treatment of benzotriazole wastewater according to claim 1, characterized in that: The cross-sections of two adjacent arc-shaped partitions are V-shaped, gradually widening towards the side away from the ultraviolet lamp tube; The inner wall of the inner bed and the two sides of the arc-shaped partition are coated with photocatalytic material.

3. The method for photosynergistic fixed-bed catalytic oxidation treatment of benzotriazole wastewater according to claim 1, characterized in that: The reaction tube, the quench dilution unit, and the gas-liquid separation unit are connected in series in the material flow direction. The quench dilution unit is used to dilute the oxygen concentration and perform preliminary cooling of the material, while the gas-liquid separation unit is used to condense and separate the gas and liquid phases. The rapid cooling and dilution unit uses a mixing tank, and the gas-liquid separation unit uses a condenser separator; The mixing tank has an inlet and an outlet pipe connected together, and an air inlet pipe connected to the top of the mixing tank, which is connected to the nitrogen supply equipment. The outlet of the mixing tank is connected to the feed end of the condenser separator via a conveying pipe; The outlet of the condenser separator is connected to the tail gas absorption tower; The liquid outlet at the bottom of the condenser is connected to the neutralization treatment unit.

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