Photoresponsive sewage treatment agent and preparation method thereof

Abstract

The invention discloses a photoresponse sewage treatment agent and a preparation method thereof, and belongs to the technical field of sewage treatment. The preparation method comprises the following steps: preparing F-BiVO4 pre-complexed colloid and Zr-O-P pre-complexed colloid, carrying out ultrasonic dispersion on the F-BiVO4 pre-complexed colloid and Zr-O-P pre-complexed colloid and carboxylated nitrogen-doped mesoporous carbon, carrying out a hydrothermal reaction, washing, and drying. The active components of the photoresponsive sewage treatment agent are uniformly loaded, the treatment capacity is dynamically improved along with the illumination intensity through the synergistic effect of photocatalytic degradation of F-BiVO4 and adsorption and fixation of Zr-O-P, organic phosphorus can be efficiently degraded, and inorganic phosphorus can be fixed. The photoresponse sewage treatment agent prepared by the method is high in adsorptive selectivity, excellent in cycling stability, firm in active component loading and adaptive to a complex wastewater system, and an efficient solution is provided for phosphorus pollution treatment.

Description

A photoresponsive wastewater treatment agent and its preparation method Technical Field

[0001] This invention relates to the field of wastewater treatment technology, and in particular to a photoresponsive wastewater treatment agent and its preparation method. Background Technology

[0002] Phosphorus pollution is one of the core causes of eutrophication in water bodies. The uncontrolled discharge of large amounts of phosphorus-containing industrial wastewater (such as pesticide, electroplating, and chemical wastewater) and domestic sewage has led to total phosphorus concentrations in water bodies far exceeding the self-purification threshold, triggering ecological crises such as algal blooms, water hypoxia, and fish deaths. It also threatens human drinking water safety, and excessive phosphorus intake may induce health risks. Among these, organophosphorus pollutants (such as glyphosate and triethyl phosphate) have stable chemical structures, are difficult to degrade, and have long residual periods in water bodies. Traditional treatment technologies struggle to completely remove them, making them a key challenge in wastewater treatment. Developing technologies for efficiently treating organophosphorus while simultaneously immobilizing inorganic phosphorus is urgently needed.

[0003] Currently, phosphorus removal technologies in wastewater treatment mainly include biological methods, chemical methods, adsorption methods, and photocatalysis. Biological methods accumulate phosphorus through the metabolism of polyphosphate-accumulating bacteria, but suffer from drawbacks such as long bacterial acclimation periods, weak resistance to shock loads, and a sharp drop in phosphorus removal efficiency at low temperatures. Chemical methods utilize iron and aluminum salts to form precipitates with phosphorus, which can rapidly reduce phosphorus levels, but require large dosages, are costly, and generate large amounts of highly moist chemical sludge, making subsequent disposal difficult. Adsorption methods capture phosphorus using the specific properties of adsorbents, offering simple operation, but traditional adsorbents (such as zeolite and activated carbon) have limited selectivity for inorganic phosphorus and almost no removal effect on organophosphorus. Photocatalysis degrades organophosphorus through active free radicals generated by semiconductor materials, but photocatalytic systems alone suffer from high carrier recombination rates, easy diffusion and loss of degradation products (inorganic phosphorus), and the inability to completely fix phosphorus, limiting their practical application.

[0004] While existing composite phosphorus removal technologies attempt to combine photocatalysis and adsorption functions, significant shortcomings remain: some schemes employ physical mixing methods to composite active components, resulting in weak interfacial bonding and uneven dispersion, hindering the synergistic effect of photocatalysis and adsorption; some photoresponsive materials lack precise structural design, leading to high recombination rates of photogenerated carriers, and the inability to dynamically control the activity of adsorption units with light intensity, limiting the improvement in treatment efficiency; furthermore, insufficient surface modification of carrier materials results in poor stability of active component loading, making them prone to detachment during recycling, affecting the sustainability and safety of treatment effects. Therefore, developing a wastewater treatment agent that combines highly efficient photocatalytic degradation of organophosphorus, targeted adsorption and fixation of inorganic phosphorus, enhanced photoresponsiveness, and excellent cycle stability has become a key direction for solving the current challenges of phosphorus pollution control. Summary of the Invention

[0005] The purpose of this invention is to overcome the shortcomings of the existing technology and to propose a photoresponsive wastewater treatment agent and its preparation method.

[0006] To achieve the above objectives, the present invention adopts the following technical solution: a method for preparing a photoresponsive wastewater treatment agent, comprising the following steps: (1) adding bismuth nitrate pentahydrate, ammonium metavanadate, and ammonium fluoride to an ethylene glycol / water mixed solution, stirring, and then adjusting the pH of the system to 5.0-5.5 with triethylamine to form an F-BiVO4 pre-complexed colloid; in this step, after bismuth nitrate pentahydrate (Bi(NO3)3・5H2O), ammonium metavanadate (NH4VO3), and ammonium fluoride (NH4F) are dissolved in the ethylene glycol / water mixed solvent, they first undergo ion dissociation and hydrolysis reactions; Bi 3+ After being released from bismuth nitrate pentahydrate, it undergoes partial hydrolysis upon reaction with water molecules in the solvent, generating Bi(OH)₂. + Intermediate products; VO3 dissociated from NH4VO3 - Further hydrolysis in aqueous solution yields the V(OH)5 precursor. Ethylene glycol added to the system plays a crucial complexing role, with its hydroxyl groups reacting with Bi... 3+ Forming stable chelate complexes, effectively inhibiting Bi 3+ Excessive hydrolysis produces Bi(OH)3 precipitate, providing a stable environment for the subsequent in-situ formation of BiVO4; the process of adjusting the pH to 5.0-5.5 with triethylamine neutralizes the H+ produced by hydrolysis. + Promote Bi 3+ The hydrolysis equilibrium with V(OH)5 shifts to the right, promoting a condensation reaction between the two to form the BiVO4 unit. The reaction equation is: Bi(NO3)3・5H2O + NH4VO3 + 3H2O → BiVO4↓ + NH4NO3 + 2HNO3 + 5H2O; simultaneously, F, released from ammonium fluoride... - Due to the ionic radius (133 pm) and O 2- (132pm) similar, can selectively replace some of the double-coordinated O atoms in the BiVO4 lattice to form an F-doped lattice defect structure. This process does not require additional energy to drive it and can be completed simply by lattice substitution, ultimately forming a stable F-BiVO4 pre-complexed colloid; (2) Zirconium oxychloride and ammonium dihydrogen phosphate are added to deionized water, and after stirring, the pH of the system is adjusted to 5.0-5.5 with triethylamine to form a Zr-OP pre-complexed colloid; after zirconium oxychloride (ZrOCl2・8H2O) is dissolved in deionized water, Zr 4+ It undergoes rapid hydrolysis to produce Zr(OH)4 colloidal particles, with the reaction formula: ZrOCl2・8H2O + 2H2O → Zr(OH)4↓ + 2HCl + 6H2O; ammonium dihydrogen phosphate (NH4H2PO4) ionizes in aqueous solution to produce H2PO4.- In an environment where the pH is adjusted to 5.0-5.5 by triethylamine, H2PO4 - Further ionization to HPO4 2- Its oxygen atoms are rich in lone pairs of electrons, which can react with Zr atoms on the Zr(OH)4 surface. 4 + (The empty 4d orbital) undergoes strong coordination to form a multidentate Zr-OP complex; in this coordination reaction, Zr 4+ As the central ion, with HPO4 2- A stable octahedral coordination structure is formed through Zr-OP covalent bonds, and the reaction formula is: Zr(OH)4 + H2PO4 - →Zr-OP (OH)2 - +2OH - +H2O; due to Zr 4+ With a high coordination number (6-8), it can form a cross-linked structure with multiple phosphate ions. In addition, the pH environment regulated by triethylamine inhibits the aggregation and precipitation of Zr(OH)4, and finally forms a stable Zr-OP pre-complexed colloid; (3) Mix F-BiVO4 pre-complexed colloid with Zr-OP pre-complexed colloid, add carboxylated nitrogen-doped mesoporous carbon, and ultrasonically disperse it evenly. Transfer it to a hydrothermal reactor with a polytetrafluoroethylene liner and carry out the reaction at 160-200℃ for 12-24h with stirring. The surface of carboxylated nitrogen-doped mesoporous carbon is rich in carboxyl groups. This functional group is generated by the oxidation of surface defect sites after nitrogen-doped mesoporous carbon undergoes oxidation and oxidation. When F-BiVO4 is mixed with Zr-OP pre-complexed colloid, the hydroxyl groups of the carboxyl groups on the surface of the mesoporous carbon can react with Bi in the colloid. 3+ Zr 4+ The empty orbitals form weak coordination bonds, while the oxygen atoms of the carboxyl group form hydrogen bonds with the hydroxyl groups on the surface of the colloidal particles. Under this dual action, the colloidal particles are rapidly adsorbed onto the inner walls and surface of the pores of the mesoporous carbon. Ultrasonic dispersion breaks the weak agglomeration forces between colloidal particles through mechanical vibration, ensuring that the colloid is uniformly dispersed in the mesoporous structure of the mesoporous carbon and guaranteeing the dispersion of the active component on the carrier. After being transferred to a hydrothermal reactor, the high-temperature environment of 160-200℃ becomes the key driving force for the solidification and bonding strengthening of the colloid. At this temperature, the ethylene glycol complexing agent in the pre-complexed colloid gradually desorbs, and Bi... 3+ The condensation reaction with V(OH)5 is further completed, forming F-BiVO4 active sites with higher crystallinity; simultaneously, the Zr-OP complex undergoes dehydration and solidification, forming a stable Zr3(PO4)4-like crystal structure. More importantly, the high temperature promotes the reaction of carboxyl groups on the mesoporous carbon surface with Bi... 3+ Zr 4+The formation of stronger coordination bonds (-COO-M, where M is Bi or Zr) transforms the physical adsorption between the active component and the support into chemical bonding, significantly improving the loading stability. In addition, the pore structure of the mesoporous carbon remains intact under hydrothermal conditions, providing sufficient channels for the mass transfer of pollutants in the subsequent wastewater treatment process. The spatial separation distribution of F-BiVO4 and Zr-OP active components within the pores avoids performance waste and lays the structural foundation for the synergistic effect of "photocatalytic degradation-adsorption fixation". (4) The reaction product obtained in (3) is cooled to room temperature, centrifuged, and washed 3-4 times alternately with deionized water and anhydrous ethanol. Then it is dried in a vacuum drying oven at 60-80℃ for 8-12 hours to obtain a photoresponsive wastewater treatment agent. After the reaction product is cooled to room temperature, centrifugation can quickly separate the mesoporous carbon particles loaded with active components from the unreacted soluble impurities (such as excess NH4). + NO3 - Solid-liquid separation is achieved through alternating washing with deionized water and anhydrous ethanol, which has a clear targeting effect: deionized water mainly removes water-soluble impurities, while anhydrous ethanol can dissolve residual ethylene glycol complexing agents and organic impurities, while reducing the surface tension of the particles and preventing the loss of active components during washing. Vacuum drying at 60-80℃ can quickly remove water and ethanol from the particle surface and pores, and because the temperature is below the structural transformation threshold of the active components, it can effectively retain the photocatalytic active structure of F-BiVO4 and the adsorption coordination structure of Zr-OP, ultimately obtaining a light-responsive wastewater treatment agent with both high-efficiency photocatalytic and adsorption performance.

[0007] Preferably, in (1), the molar ratio of bismuth nitrate pentahydrate, ammonium metavanadate, and ammonium fluoride is 1:1:0.01-0.12.

[0008] Preferably, the weight ratio of bismuth nitrate pentahydrate and ethylene glycol / water mixed solution in (1) is 1:6-8.

[0009] Preferably, the volume ratio of ethylene glycol to water in the ethylene glycol / water mixed solution in (1) is 1:1.

[0010] Preferably, the stirring time in (1) is 20-40 min.

[0011] Preferably, the molar ratio of zirconium oxychloride and ammonium dihydrogen phosphate in (2) is 1:1.2-1.5.

[0012] Preferably, in step (2), the ratio of zirconium oxychloride to deionized water is 1:5-10 by weight.

[0013] Preferably, the stirring time in (2) is 30-60 min.

[0014] Preferably, in (3), the F-BiVO4 pre-complexed colloid, Zr-OP pre-complexed colloid and carboxylated nitrogen-doped mesoporous carbon are in a weight ratio of 4-6:2-3:1.

[0015] Preferably, the ultrasonic dispersion time in (3) is 10-30 min, the frequency is 15-25 kHz, and the power is 300-500 W.

[0016] Preferably, the method for preparing carboxylated nitrogen-doped mesoporous carbon in (3) includes the following steps: immersing nitrogen-doped mesoporous carbon in a 30% hydrogen peroxide solution with pH adjusted to 2.0-3.0 by dilute sulfuric acid, heating to 35-45℃ and stirring at a constant temperature for 4-8 hours to obtain an oxidation treatment solution; filtering the oxidation treatment solution, collecting the solid product, washing with deionized water until the filtrate is neutral; and then drying in a vacuum drying oven at 50-70℃ for 8-12 hours to obtain carboxylated nitrogen-doped mesoporous carbon.

[0017] More preferably, the method for preparing carboxylated nitrogen-doped mesoporous carbon in (3) includes the following steps: immersing nitrogen-doped mesoporous carbon in a 30% hydrogen peroxide solution with pH adjusted to 2.0-3.0 by dilute sulfuric acid, heating to 40°C and stirring at a constant temperature for 6 hours to obtain an oxidation treatment solution; filtering the oxidation treatment solution, collecting the solid product, washing with deionized water until the filtrate is neutral; and then drying in a vacuum drying oven at 60°C for 12 hours to obtain carboxylated nitrogen-doped mesoporous carbon.

[0018] Preferably, in the method for preparing carboxylated nitrogen-doped mesoporous carbon, the average length of the nitrogen-doped mesoporous carbon is 1 μm, and the specific surface area is ≥350 m². 2 / g, pore size approximately 4.83nm, nitrogen content approximately 6.7at.

[0019] Furthermore, the present invention also provides a photoresponsive wastewater treatment agent, which is prepared by the above-described method for preparing a photoresponsive wastewater treatment agent.

[0020] Preferably, the mechanism of action of the photoresponsive wastewater treatment agent of the present invention is explained as follows: The core of the photoresponsiveness of the wastewater treatment agent of the present invention originates from the semiconductor photocatalytic properties of F-doped BiVO4 (F-BiVO4). Its degradation effect on organophosphorus pollutants in wastewater depends on visible light-driven carrier separation and active free radical generation. The band gap of F-BiVO4 is narrowed by F doping, which effectively absorbs visible light. When visible light irradiates the material surface, electrons (e) in the valence band of F-BiVO4... - The electron undergoes a jump to the conduction band, simultaneously leaving a hole in the valence band (h). + The process involves the formation of electron-hole pairs, with the core reaction being: F-BiVO4 + hν (visible light) → F-BiVO4 (hν). + ₍VB₎ + e- ₍CB₎); Light intensity is a key factor in regulating the efficiency of this process, and as light intensity increases (e.g., from 100 mW / cm²), the efficiency of this process increases. 2 Increased to 300 mW / cm 2 The number of photons irradiating the F-BiVO4 surface per unit time increases proportionally, more valence band electrons gain enough energy to jump to the conduction band, and the total number of generated electron-hole pairs increases significantly (carrier concentration increases). This is because F... - The lattice defects formed by replacing some O atoms in the BiVO4 lattice can act as electron traps, effectively suppressing recombination even with an increased number of charge carriers. This provides ample support for the generation of active free radicals. The valence band holes have extremely strong oxidizing power, directly capturing electrons from water molecules (H2O) adsorbed on the material surface and oxidizing them to generate hydroxyl radicals (·OH). The reaction formula is h. + ₍VB₎ +H₂O→·OH+H + Higher light intensity results in more holes and a faster ·OH generation rate. Hydroxyl radicals, as strong oxidizing agents, can non-selectively attack the active functional groups such as CP and CCC bonds in organophosphorus pollutants (e.g., glyphosate, triethyl phosphate), gradually degrading them into inorganic phosphate (PO4). 3- Simultaneously, it is mineralized into CO2 and H2O. Taking glyphosate (C3H8NO5P), a typical organophosphorus pollutant, as an example, its degradation reaction formula is: C3H8NO5P + 10·OH → 3CO2↑ +NH4 + +PO4 3- + 7H2O+H + The increase in OH concentration directly accelerates the rate of this degradation reaction, increasing the amount of organophosphorus converted into inorganic phosphorus per unit time.

[0021] PO4 generated by photocatalytic degradation 3- Zr migrates to Zr-OP adsorption sites through internal mass transfer channels, achieving efficient adsorption and fixation through multiple synergistic effects. This process is primarily chemisorption, but also exhibits physical adsorption characteristics, ensuring the stability and selectivity of the adsorption. In the Zr-OP structure, Zr... 4+ As a typical hard Lewis acid, its empty 4d orbital can interact with PO4. 3- In a hard Lewis base, the lone pair electrons of the oxygen atom form stable octahedral coordinate bonds, constructing an inner spherical complex structure. The core equation for this coordination reaction is: Zr-OP(OH)2 - +PO4 3- → Zr-OPO-PO3 3- +2OH - The bond energy of the formed Zr3(PO4)4 chelate is much higher than that of physical adsorption, ensuring that PO4 3-It does not easily desorb; as the light intensity increases, the number of photogenerated electrons in the conduction band of F-BiVO4 increases synchronously. These electrons are directionally transported to the Zr-OP unit through the nitrogen-doped sites of carboxylated nitrogen-doped mesoporous carbon, making Zr... 4+ The electron cloud density is rearranged, the exposure of empty d orbitals is further increased, the activity of Lewis acids is significantly enhanced, and it interacts with PO4. 3- The coordination binding ability is stronger; at the same time, the electron transport process promotes the deprotonation reaction of hydroxyl groups on the Zr-OP surface to generate more Zr-O. - Active site, ligand exchange reaction (Zr(OH)4+PO4) 3- → ZrPO4 - +4OH - The rate of adsorption of PO4 in the wastewater increases, and the adsorption capacity increases simultaneously. Furthermore, increased light intensity further raises the surface positive potential of Zr-OP sites, while the PO4 in the wastewater... 3- In natural aquatic environments, it mainly exists as HPO4. 2- PO4 3- The electrostatic attraction between the two forms can accelerate the reaction of PO4. 3- Diffusion to adsorption sites shortens the adsorption equilibrium time, and the three-dimensional cross-linked structure of Zr-OP can also repel SO4 through steric hindrance. 2- Cl - The coexistence of anions makes the adsorption process highly selective and unaffected by other ions in complex wastewater systems.

[0022] The wastewater treatment capacity of this invention significantly increases with light intensity, primarily due to the positive correlation between the synergistic effect of "photocatalytic degradation-adsorption fixation" and light intensity. The high specific surface area and mesoporous structure of carboxylated nitrogen-doped mesoporous carbon provide ample channels for pollutant transport, ensuring that rapidly generated organophosphorus degradation products under high light intensity can diffuse to adsorption sites in a timely manner, avoiding the accumulation of intermediate products that inhibit the photocatalytic reaction. The nitrogen-doped sites (approximately 6.7 at%) in the mesoporous carbon exhibit excellent electron transport performance, acting as electron bridges to promote the directional transport of photogenerated electrons from the conduction band of F-BiVO4 to the Zr-OP unit. This electron transfer process not only further suppresses electron-hole recombination in F-BiVO4 but also regulates the electron cloud distribution of Zr-OP: electrons are transferred to Zr... 4+ After the empty orbit, make Zr 4+ The activity of Lewis acids is enhanced, with PO4 3- The coordination binding energy is enhanced, and the deprotonation of hydroxyl groups on the Zr-OP surface is promoted, generating more active adsorption sites (Zr-O). -This achieves "dynamic enhancement of adsorption activity driven by photogenerated electrons"; when the light intensity increases, the degradation rate of organophosphorus compounds by F-BiVO4 and the adsorption rate of inorganic phosphorus compounds by Zr-OP accelerate synchronously, forming a positive cycle of "accelerated degradation - synchronous enhancement of adsorption": under high light irradiation, the production of ·OH increases, the degradation rate of organophosphorus compounds increases, and the generated PO4 3- The concentration increases instantaneously; however, the simultaneously enhanced adsorption activity of Zr-OP can rapidly capture these PO4 groups. 3- Reduce PO4 in the reaction system 3- According to Le Chatelier's principle, the concentration of high light intensity further promotes the positive shift of the organophosphorus degradation reaction equilibrium, achieving a synergistic acceleration of degradation and adsorption. Furthermore, under high light irradiation, more photogenerated electrons are transported to Zr-OP via the carrier, not only enhancing adsorption activity but also further inhibiting electron-hole recombination in F-BiVO4, thus maintaining high photocatalytic efficiency. This synergistic enhancement effect driven by light intensity ultimately manifests as a significant increase in the total phosphorus removal rate and degradation rate of the wastewater treatment agent with increasing light intensity, demonstrating a clear light-response enhancement characteristic.

[0023] Compared with the prior art, the beneficial effects of the present invention are: 1. The present invention constructs a highly efficient photocatalytic unit by modifying BiVO4 with F doping, F - The lattice substitution effect narrows the band gap and enhances visible light absorption. At the same time, the lattice defects formed can capture photogenerated electrons, significantly suppress carrier recombination, and improve the generation efficiency of hydroxyl radicals. Combined with the electron transport function of Zr-OP adsorption units and nitrogen-doped mesoporous carbon, the photogenerated electrons can dynamically regulate the adsorption activity, so that the catalytic degradation and adsorption fixation rates can be increased synchronously with the light intensity, forming a positive cycle of "light intensity enhancement - dual-function synergistic enhancement", which can efficiently complete the integrated treatment of organophosphorus degradation and inorganic phosphorus fixation.

[0024] 2. The carboxyl groups on the surface of the carboxylated nitrogen-doped mesoporous carbon used in this invention react with the Bi in the active component. 3+ Zr 4+ By forming stable coordination bonds, the active components are transformed from physical adsorption to chemical bonding loading, which greatly reduces the risk of detachment during use and regeneration. The hydrothermal process further enhances the crystallinity and solidification of the active components, ensuring that the material can maintain its complete structure and sufficient active sites after multiple "adsorption-desorption-regeneration" cycles, eliminating the need for frequent replacement, reducing practical application costs, and providing the ability to treat wastewater stably for a long time.

[0025] 3. In this invention, the Zr-OP unit of the wastewater treatment agent, through its three-dimensional cross-linked structure and coordination with hard acid-hard base, forms a specific targeted adsorption of inorganic phosphorus, effectively repelling Cl through steric hindrance. - SO4 2-The presence of coexisting anions avoids competitive adsorption. The high specific surface area and suitable pore size of carboxylated nitrogen-doped mesoporous carbon provide a smooth channel for pollutant transport, ensuring that phosphorus components can still be accurately captured in complex wastewater environments such as high-salt wastewater, without interference from other ions in the system, thus broadening the applicable scenarios of wastewater treatment agents.

[0026] 4. This invention employs a pre-complexed colloid in-situ assembly process, with clear steps, requiring no complex equipment or harsh reaction conditions. Raw materials are readily available and costs are controllable. The combination of ultrasonic dispersion and hydrothermal curing ensures that the active components are uniformly dispersed in the carrier channels and surface, avoiding performance waste caused by agglomeration. Subsequent washing and drying steps specifically remove impurities, ensuring product purity and activity. The entire preparation process is easy to operate and scale up, enabling large-scale production and laying the foundation for the industrial application of wastewater treatment agents. Detailed Implementation

[0027] The technical solutions in the embodiments of the present invention will be clearly and completely described below in conjunction with existing known technologies. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments.

[0028] Preparation Example: A specific preparation method for carboxylated nitrogen-doped mesoporous carbon includes the following steps: Nitrogen-doped mesoporous carbon was purchased from Jiangsu Xianfeng Nanomaterials Technology Co., Ltd., model: XFP14, with an average length of 1 μm and a specific surface area ≥350 m². 2 / g, pore size approximately 4.83nm, nitrogen content approximately 6.7at.

[0029] 10g of nitrogen-doped mesoporous carbon was immersed in a 30% hydrogen peroxide solution with pH adjusted to 2.0-3.0 by dilute sulfuric acid, and the solution was heated to 40℃ and stirred for 6h to obtain an oxidation treatment solution. The oxidation treatment solution was filtered, the solid product was collected, and washed with deionized water until the filtrate was neutral. Then it was placed in a vacuum drying oven at 60℃ and dried for 12h to obtain carboxylated nitrogen-doped mesoporous carbon.

[0030] Comparative preparation example: The difference between the comparative preparation example and the preparation example is that nitrogen-doped mesoporous carbon is replaced with mesoporous carbon.

[0031] Example 1: A specific preparation method of a photoresponsive wastewater treatment agent, comprising the following steps: (1) Adding 100g of bismuth nitrate pentahydrate, 24.12g of ammonium metavanadate and 0.08g of ammonium fluoride to 600g of ethylene glycol / water mixed solution (the volume ratio of ethylene glycol to water is 1:1), stirring for 20min, and then adjusting the pH of the system to 5.0-5.5 with triethylamine to form F-BiVO4 pre-complexed colloid; (2) Adding 100g of zirconium oxychloride and 77.49g of ammonium dihydrogen phosphate to 500g of deionized water, stirring for 30min, and then adjusting the pH of the system to 5.0-5.5 with triethylamine to form Zr-OP pre-complexed colloid; (3) Adding 400g of F-BiVO4 pre-complexed colloid and 200g of... Zr-OP pre-complexed colloid was mixed and 100g of carboxylated nitrogen-doped mesoporous carbon prepared according to Preparation Example 1 was added and ultrasonically dispersed evenly. The ultrasonic time was 10min, the frequency was 15kHz, and the power was 300W. The mixture was transferred to a hydrothermal reactor with a polytetrafluoroethylene liner and stirred at 160℃ for 12h. (4) The reaction product obtained in (3) was cooled to room temperature, centrifuged, and washed 3-4 times alternately with deionized water and anhydrous ethanol. Then it was placed in a vacuum drying oven at 60℃ and dried for 8h to obtain a photoresponsive wastewater treatment agent.

[0032] Example 2: A specific preparation method of a photoresponsive wastewater treatment agent, comprising the following steps: (1) Adding 100g of bismuth nitrate pentahydrate, 24.12g of ammonium metavanadate and 0.61g of ammonium fluoride to 700g of ethylene glycol / water mixed solution (the volume ratio of ethylene glycol to water is 1:1), stirring for 30min, and then adjusting the pH of the system to 5.0-5.5 with triethylamine to form F-BiVO4 pre-complexed colloid; (2) Adding 100g of zirconium oxychloride and 87.18g of ammonium dihydrogen phosphate to 800g of deionized water, stirring for 40min, and then adjusting the pH of the system to 5.0-5.5 with triethylamine to form Zr-OP pre-complexed colloid; (3) Adding 500g of F-BiVO4 pre-complexed colloid and 250g of... Zr-OP pre-complexed colloid was mixed, and 100g of carboxylated nitrogen-doped mesoporous carbon prepared according to the preparation example was added and ultrasonically dispersed evenly. The ultrasonic time was 20min, the frequency was 20kHz, and the power was 400W. The mixture was transferred to a hydrothermal reactor with a polytetrafluoroethylene liner and stirred at 180℃ for 18h. (4) The reaction product obtained in (3) was cooled to room temperature, centrifuged, and washed 3-4 times alternately with deionized water and anhydrous ethanol. Then it was placed in a vacuum drying oven at 70℃ and dried for 10h to obtain a photoresponsive wastewater treatment agent.

[0033] Example 3: A specific preparation method of a photoresponsive wastewater treatment agent, comprising the following steps: (1) Adding 100g of bismuth nitrate pentahydrate, 24.12g of ammonium metavanadate and 0.92g of ammonium fluoride to 800g of ethylene glycol / water mixed solution (the volume ratio of ethylene glycol to water is 1:1), stirring for 40min, and then adjusting the pH of the system to 5.0-5.5 with triethylamine to form F-BiVO4 pre-complexed colloid; (2) Adding 100g of zirconium oxychloride and 96.86g of ammonium dihydrogen phosphate to 1kg of deionized water, stirring for 60min, and then adjusting the pH of the system to 5.0-5.5 with triethylamine to form Zr-OP pre-complexed colloid; (3) Adding 600g of F-BiVO4 pre-complexed colloid and 300g of... Zr-OP pre-complexed colloid was mixed, and 100g of carboxylated nitrogen-doped mesoporous carbon was added and ultrasonically dispersed evenly. The ultrasonic time was 30min, the frequency was 25kHz, and the power was 500W. The mixture was then transferred to a hydrothermal reactor with a polytetrafluoroethylene liner and stirred at 200℃ for 24h. (4) The reaction product obtained in (3) was cooled to room temperature, centrifuged, and washed 3-4 times alternately with deionized water and anhydrous ethanol. It was then placed in an 80℃ vacuum drying oven and dried for 12h to obtain a photoresponsive wastewater treatment agent.

[0034] Comparative Example 1: The difference between Comparative Example 1 and Example 2 is that ammonium fluoride is not added in step (1).

[0035] Comparative Example 2: The difference between Comparative Example 2 and Example 2 is that ammonium dihydrogen phosphate is not added in step (2).

[0036] Comparative Example 3: The difference between Comparative Example 3 and Example 2 is that the carboxylated nitrogen-doped mesoporous carbon prepared in step (3) according to the preparation example is replaced with nitrogen-doped mesoporous carbon.

[0037] Comparative Example 4: The difference between Comparative Example 4 and Example 3 is that the carboxylated nitrogen-doped mesoporous carbon prepared according to the preparation example in step (3) is replaced with the carboxylated mesoporous carbon prepared according to the comparative preparation example.

[0038] Comparative Example 5: The difference between Comparative Example 4 and Example 2 is that step (2) is omitted and Zr-OP pre-complexed colloid is not added in step (3).

[0039] Comparative Example 6: The difference between Comparative Example 6 and Example 2 is that the active component is combined with a porous carbon support by physical mixing. The specific preparation method is as follows: A specific preparation method of a photoresponsive wastewater treatment agent includes the following steps: (1) 100g of bismuth nitrate pentahydrate, 24.12g of ammonium metavanadate and 0.61g of ammonium fluoride are added to 700g of ethylene glycol / water mixed solution (ethylene glycol and water volume ratio 1:1), stirred for 30min, and then the pH of the system is adjusted to 5.0-5.5 with triethylamine to form F-BiVO4 pre-complexed colloid; the colloid is transferred to a hydrothermal reactor with a polytetrafluoroethylene liner, and reacted at a constant temperature of 180℃ for 18h. After the reaction is completed, it is cooled to room temperature, centrifuged, and the solid product is collected. (1) Wash 3-4 times with deionized water and anhydrous ethanol alternately, and dry in a vacuum drying oven at 70℃ for 10h to obtain crystalline F-BiVO4 powder; (2) Add 100g zirconium oxychloride and 87.18g ammonium dihydrogen phosphate to 800g deionized water, stir for 40min, and adjust the pH of the system to 5.0-5.5 with triethylamine to form Zr-OP pre-complexed colloid; transfer the colloid to a hydrothermal reactor with a polytetrafluoroethylene liner, react at 180℃ for 18h, cool to room temperature after the reaction, centrifuge, collect the solid product, wash 3-4 times with deionized water and anhydrous ethanol alternately, and dry in a vacuum drying oven at 70℃ for 10h to obtain crystalline Zr-OP powder; (3) Add 45g F-BiVO4 powder, 22.5g of Zr-OP powder prepared above, and 100g of carboxylated nitrogen-doped mesoporous carbon obtained in the preparation example were added together into a high-speed mixer and mechanically stirred at 300r / min for 30min to obtain a physically mixed photoresponsive wastewater treatment agent.

[0040] Performance Testing: 1. Total Phosphorus Removal Rate Test: Prepare glyphosate-simulated wastewater with an initial total phosphorus concentration of 50 mg / L. Weigh 0.1 g of the wastewater treatment agents from Examples 1-3 and Comparative Examples 1-6 respectively, add them to 100 mL of the simulated wastewater, and place them in a visible light photocatalytic reactor (light intensity fixed at 200 mW / cm²). 2 The reaction temperature was 25℃, and the magnetic stirring speed was 300 r / min. Samples were taken at 0, 30, 60, 90, and 120 min of reaction. After filtration through a 0.22 μm filter membrane, the total phosphorus concentration in the filtrate was determined by molybdenum antimony spectrophotometry. The total phosphorus removal rate at different reaction times was calculated (removal rate = (initial total phosphorus concentration - remaining total phosphorus concentration) / initial total phosphorus concentration × 100%). The experimental results are shown in Table 1.

[0041] 2. Maximum Adsorption Capacity Test: The wastewater treatment agents prepared in Examples 1-3 and Comparative Examples 1-6 were selected as test objects, and the maximum adsorption capacity was determined by static adsorption experiments. A series of inorganic phosphorus simulated wastewaters (using potassium dihydrogen phosphate as the phosphorus source) with initial total phosphorus concentrations of 10, 20, 50, 100, 200, and 300 mg / L were prepared. 100 mL of each concentration of wastewater was placed in an Erlenmeyer flask, and 0.1 g of sample was added. Adsorption was carried out at 25℃ and 300 r / min under magnetic stirring in the dark for 24 h. After the reaction, samples were filtered, and the residual phosphorus concentration in the filtrate was determined by molybdenum-antimony spectrophotometry. The adsorption capacity per unit mass of sample was calculated (adsorption capacity = (initial concentration - equilibrium concentration) × solution volume / sample mass). Based on the adsorption capacity data corresponding to different initial concentrations, the maximum adsorption capacity of each sample was obtained by fitting the Langmuir adsorption isotherm model. The experimental results are shown in Table 1.

[0042] 3. Cyclic Stability Test: Using the wastewater treatment agents prepared in Examples 1-3 and Comparative Examples 1-6 as test objects, after completing the first treatment under the same conditions as the total phosphorus removal rate test, the reacted wastewater treatment agents were centrifuged, washed three times with deionized water, and then soaked in 0.5 mol / L hydrochloric acid solution for 30 min to achieve desorption and regeneration. After washing until neutral, they were vacuum dried for later use. The above "adsorption-desorption-regeneration" cycle process was repeated for a total of 10 cycles. The total phosphorus removal rate after each cycle was recorded, and the ratio of the total phosphorus removal rate after the 10th cycle to that after the first cycle was calculated to obtain the total phosphorus removal rate retention rate. The experimental results are shown in Table 1.

[0043] Table 1. Results of total phosphorus removal rate, maximum adsorption capacity, and cycle stability tests. 4. Effect of light intensity on treatment efficiency test: Using the wastewater treatment agents prepared in Examples 1-3 and Comparative Examples 1-6 as test objects, glyphosate simulated wastewater with an initial total phosphorus concentration of 50 mg / L was prepared. 0.1 g of sample was weighed and added to 100 mL of simulated wastewater and placed in a visible light photocatalytic reactor (reaction temperature 25℃, magnetic stirring speed 300 r / min). The light intensity was set to 100 mW / cm². 2 200 mW / cm 2 300 mW / cm 2 Three light intensities were used. The reaction was carried out for 120 min at each light intensity. After the reaction, samples were taken and filtered. The total phosphorus concentration in the filtrate was determined by the molybdenum-antimony spectrophotometric method, and the total phosphorus removal rate was calculated. The experimental results are shown in Table 2.

[0044] 5. Adsorption Selectivity Test: A glyphosate-simulated wastewater containing multiple coexisting anions was prepared, with a total phosphorus concentration of 50 mg / L, and Cl- was added simultaneously. - SO42- NO3 - Three coexisting anions (each anion concentration of 500 mg / L, simulating a high-salt wastewater environment). Weigh 0.1 g of the wastewater treatment agent from Examples 1-3 and Comparative Examples 1-6, add it to 100 mL of the above-mentioned simulated wastewater, and apply it under a light intensity of 200 mW / cm². 2 The reaction was carried out at 25℃ and 300 r / min for 120 min. After filtration, the total phosphorus concentration was determined by the molybdenum antimony spectrophotometric method, and the total phosphorus removal rate was calculated. The experimental results are shown in Table 2.

[0045] 6. Stability Test of Active Component Loading: The wastewater treatment agents prepared in Examples 1-3 and Comparative Examples 1-6 were selected as test objects. After treatment according to the standard conditions for total phosphorus removal rate testing, the reaction solution was centrifuged at 8000 r / min for 10 min, and the supernatant was collected. The dissolution concentrations of Bi and Zr elements (corresponding to Zr-OP active components) in the supernatant were determined by atomic absorption spectrophotometry. The experimental results are shown in Table 2.

[0046] Table 2. Test results of total phosphorus removal rate, adsorption selectivity, and active component loading stability under different light intensities. Data Analysis: As can be seen from the experimental data in Tables 1-2, the photoresponsive wastewater treatment agents prepared by the technical solution of the present invention in Examples 1-3, with the synergistic design of F-BiVO4 photocatalytic unit, Zr-OP adsorption unit and carboxylated nitrogen-doped mesoporous carbon support, exhibit excellent performance in terms of total phosphorus removal efficiency, photoresponsive characteristics, adsorption selectivity, cycle stability and active component loading stability, which are significantly better than the comparative examples. Among them, the comprehensive performance of Example 2 is the most outstanding.

[0047] The extremely high total phosphorus removal rate in Example 2 is likely due to the highly efficient synergistic mechanism of photocatalysis and adsorption. The moderate F doping in its F-BiVO4 effectively traps photogenerated electrons and suppresses carrier recombination through lattice defects, while also narrowing the band gap and enhancing visible light absorption. This maintains the hydroxyl radical generation rate at an optimal level, rapidly breaking the CP and C-C bonds of organophosphorus pollutants and degrading them into inorganic phosphate. Simultaneously, under the directional transport regulation of photogenerated electrons, the Zr-OP adsorption unit... 4+ With its empty d orbitals fully exposed, Lewis acid activity is enhanced, enabling it to rapidly capture PO4 generated during degradation through coordination and electrostatic attraction. 3-This avoids the accumulation of intermediate products that inhibit photocatalytic reactions, forming a positive cycle of "degradation-adsorption". In addition, the high specific surface area and suitable pore size of carboxylated nitrogen-doped mesoporous carbon provide smooth channels for pollutant transport and product diffusion, further improving the overall efficiency of total phosphorus removal.

[0048] Example 2 exhibits the best photoresponse sensitivity, likely because the F doping in F-BiVO4 creates lattice defects with a reasonable density. These defects act as electron traps, efficiently capturing the increased photogenerated electrons as light intensity increases, preventing an increase in carrier recombination rate, while ensuring a sufficient number of valence band holes for continuous and efficient ·OH generation. Simultaneously, the nitrogen-doped sites in the carboxylated nitrogen-doped mesoporous carbon act as electron bridges, directionally transporting photogenerated electrons to the Zr-OP unit, enabling Zr… 4+ The electron cloud density is rearranged, and the adsorption activity is enhanced synchronously with the light intensity, realizing the synergistic effect of "increased light intensity - increased charge carriers - dual enhancement of catalysis and adsorption".

[0049] The maximum adsorption capacity advantage of Example 2 stems from the efficient construction of Zr-OP adsorption units and the regulation of photogenerated electrons. The hydrothermal process allows for the complete dehydration and solidification of the Zr-OP complex, forming a stable and sufficiently dense Zr3(PO4)4 type crystal structure. 4+ As a hard Lewis acid, it can react with PO4. 3- A stable inner spherical complex structure is formed, with a significantly higher density of coordination adsorption sites than other samples. Simultaneously, photogenerated electrons from F-BiVO4 are directionally transported to the Zr-OP unit via nitrogen-doped mesoporous carbon, prompting deprotonation of the hydroxyl groups on the Zr-OP surface and generating more Zr-O. - The active adsorption sites further enhance the adsorption capacity for PO4. 3- The adsorption capacity is high. Furthermore, the mesoporous structure of the carboxylated nitrogen-doped mesoporous carbon ensures uniform dispersion of the Zr-OP active component, preventing aggregation and allowing more adsorption sites to connect with PO4. 3- Sufficient contact ensures that the adsorption capacity is fully utilized.

[0050] The excellent cycling stability of Example 2 is due to the strong chemical bond between its active component and the support. The carboxyl groups on the surface of carboxylated nitrogen-doped mesoporous carbon interact with the Bi groups in F-BiVO4. 3+ Zr in Zr-OP 4+The formation of stable coordination bonds (-COO-M) transforms the active component from physical adsorption to chemical bonding loading, significantly improving its stability during recycling and desorption / regeneration processes. Simultaneously, the optimized F doping amount and hydrothermal process balance the crystallinity of F-BiVO4 and the solidification degree of Zr-OP, preventing performance degradation due to structural wear or detachment of the active component during recycling. Furthermore, the pore structure of the mesoporous carbon remains intact during recycling, providing continuous protection for pollutant transport and active site exposure, enabling the wastewater treatment agent to maintain a high total phosphorus removal rate even after multiple "adsorption-desorption-regeneration" cycles.

[0051] Example 2 maintains excellent adsorption selectivity in high-salinity wastewater environments, thanks to the targeted adsorption properties of the Zr-OP structure. The three-dimensional cross-linked structure of Zr-OP effectively repels Cl through steric hindrance. - SO4 2- The coexistence of anions reduces competition for adsorption sites. Meanwhile, Zr... 4+ With PO4 3- The hard acid-hard base coordination between them is highly specific, combined with the Zr modulation brought about by photogenerated electrons. 4+ The increased Lewis acid activity enhances Zr-OP's response to PO4. 3- The adsorption affinity of the carbon is much higher than that of other anions. The surface charge characteristics of carboxylated nitrogen-doped mesoporous carbon further enhance this selectivity, avoiding the interference of coexisting anions in high-salt environments on the total phosphorus removal effect, and ensuring the reliability of its application in complex wastewater systems.

[0052] In Example 2, the extremely low dissolution concentrations of Bi and Zr demonstrate excellent stability of the active component loading. This is attributed to the chemical bonding between the carboxylated nitrogen-doped mesoporous carbon and the active component. The carboxyl groups on the surface of the mesoporous carbon coordinate with Bi through coordination bonds. 3+ Zr 4+ The tight bond forms a strong interfacial interaction, effectively inhibiting the detachment and dissolution of active components during reaction and cycling. The optimized hydrothermal process further enhances this chemical bonding effect, significantly improving the interfacial compatibility of F-BiVO4 and Zr-OP with the support and avoiding the problem of easy detachment of active components caused by physical adsorption. Furthermore, the uniform dispersion of F-BiVO4 and Zr-OP within the support pores reduces stress concentration caused by local agglomeration, further lowering the risk of dissolution of active components and ensuring the long-term stable use of the material.

[0053] Comparative Example 1 (without F doping): Compared to Example 2, the lack of F element to modify the BiVO4 lattice resulted in the BiVO4 band gap not being narrowed, weak visible light absorption, high photogenerated carrier recombination rate, insufficient hydroxyl radical generation, and a significant decrease in the organophosphorus degradation rate. Simultaneously, the absence of F-induced lattice defects prevented effective regulation of Zr-OP adsorption activity, resulting in a lack of photoresponse synergy and ultimately performance far below that of Example 2. Comparative Example 2 (without P component): Without the addition of ammonium dihydrogen phosphate, Zr-OP adsorption units could not be formed, relying solely on the physical adsorption of Zr(OH)4. The adsorption site density was extremely low and lacked targeting selectivity, leading to poor photocatalytic degradation of PO4. 3- Unable to be efficiently captured, Zr(OH)4 accumulates and inhibits the forward photocatalytic reaction. Furthermore, the weak binding force between Zr(OH)4 and the support makes it prone to detachment during cycling, resulting in significantly lower total phosphorus removal rate, adsorption capacity, and cycling stability compared to Example 2. Comparative Example 3 (uncarboxylated support): Nitrogen-doped mesoporous carbon without oxidation-hydrogenation was used as the support. Lacking carboxyl functional groups on its surface, it cannot bind with Bi. 3+ Zr 4+ Coordination bonds are formed, and the active component and the support are only physically adsorbed, resulting in poor dispersion uniformity and weak binding force. During the cycle, the active component is prone to agglomeration and detachment, and electron transport is hindered, leading to a weakened photocatalytic-adsorption synergistic effect. The total phosphorus removal rate, cycle stability, and loading stability are all inferior to those of Example 2. Comparative Example 4 (nitrogen-free support): The support is carboxylated mesoporous carbon without nitrogen doping, lacking the electron transport channels provided by nitrogen doping sites. Photogenerated electrons cannot be directionally transferred from F-BiVO4 to Zr-OP units. 4+ The electron cloud rearrangement effect is weakened, and the adsorption activity regulation fails. At the same time, the lack of nitrogen doping reduces the interaction between the support and the active component, resulting in lower total phosphorus removal rate, photoresponse characteristics, and adsorption selectivity compared to Example 2. Comparative Example 5 (without Zr-OP): The Zr-OP pre-complexed colloid preparation step is omitted, and only the F-BiVO4 photocatalytic unit exists. There is no adsorption unit to capture the PO4 generated by degradation. 3- PO4 3- Accumulation in the system inhibits the forward progress of the photocatalytic reaction, making it impossible to achieve the synergistic effect of "degradation-adsorption". As a result, the total phosphorus removal rate, adsorption capacity and light response enhancement effect are significantly worse than those of Example 2. Comparative Example 6 (physical mixing): The method of "preparing active component powder separately + mechanical stirring and mixing" was adopted. The process of "pre-complexed colloid-ultrasonic dispersion-hydrothermal curing" was not carried out. The active component and the carrier, as well as the active component, only had physical contact and no chemical bonding. There were interfacial gaps, which led to blocked electron transport, low mass transfer efficiency, uneven dispersion of active components and easy agglomeration and detachment. The light response characteristics, cycle stability and load stability were the worst among all samples, far inferior to Example 2.

[0054] The above description is only a preferred embodiment of the present invention, but the scope of protection of the present invention is not limited thereto. Any equivalent substitutions or modifications made by those skilled in the art within the scope of the technology disclosed in the present invention, based on the technical solution and inventive concept of the present invention, should be covered within the scope of protection of the present invention.

Claims

1. A method for preparing a photoresponsive wastewater treatment agent, characterized in that, Includes the following steps: (1) Add bismuth nitrate pentahydrate, ammonium metavanadate and ammonium fluoride to a ethylene glycol / water mixed solution, stir and adjust the pH of the system to 5.0-5.5 with triethylamine to form F-BiVO4 pre-complexed colloid; (2) Add zirconium oxychloride and ammonium dihydrogen phosphate to deionized water, stir, and adjust the pH of the system to 5.0-5.5 with triethylamine to form Zr-OP pre-complexed colloid; (3) Mix F-BiVO4 pre-complexed colloid with Zr-OP pre-complexed colloid, add carboxylated nitrogen-doped mesoporous carbon, disperse evenly by ultrasonication, transfer to a hydrothermal reactor with polytetrafluoroethylene liner, carry out the reaction at 160-200℃, and stir for 12-24h; (4) Cool the reaction product obtained in (3) to room temperature, centrifuge, wash with deionized water and anhydrous ethanol alternately 3-4 times, and then dry in a vacuum drying oven at 60-80℃ for 8-12h to obtain a photoresponsive wastewater treatment agent.

2. The method for preparing the photoresponsive wastewater treatment agent according to claim 1, characterized in that, In (1), the molar ratio of bismuth nitrate pentahydrate, ammonium metavanadate, and ammonium fluoride is 1:1:0.01-0.12; the weight ratio of bismuth nitrate pentahydrate and ethylene glycol / water mixed solution is 1:6-8; and the volume ratio of ethylene glycol and water in the ethylene glycol / water mixed solution is 1:

1.

3. The method for preparing the photoresponsive wastewater treatment agent according to claim 1, characterized in that, The stirring time in (1) is 20-40 min.

4. The method for preparing the photoresponsive wastewater treatment agent according to claim 1, characterized in that, In (2), the molar ratio of zirconium oxychloride and ammonium dihydrogen phosphate is 1:1.2-1.5; the weight ratio of zirconium oxychloride and deionized water is 1:5-10.

5. The method for preparing the photoresponsive wastewater treatment agent according to claim 1, characterized in that, The stirring time in (2) is 30-60 min.

6. The method for preparing the photoresponsive wastewater treatment agent according to claim 1, characterized in that, In (3), the F-BiVO4 pre-complexed colloid, Zr-OP pre-complexed colloid, and carboxylated nitrogen-doped mesoporous carbon are in a weight ratio of 4-6:2-3:

1.

7. The method for preparing the photoresponsive wastewater treatment agent according to claim 1, characterized in that, The ultrasonic dispersion time in (3) is 10-30 min, the frequency is 15-25 kHz, and the power is 300-500 W.

8. The method for preparing the photoresponsive wastewater treatment agent according to claim 1, characterized in that, The method for preparing carboxylated nitrogen-doped mesoporous carbon in (3) includes the following steps: immersing nitrogen-doped mesoporous carbon in a 30% hydrogen peroxide solution with pH adjusted to 2.0-3.0 by dilute sulfuric acid, heating to 35-45℃ and stirring at a constant temperature for 4-8 hours to obtain an oxidation treatment solution; filtering the oxidation treatment solution, collecting the solid product, washing with deionized water until the filtrate is neutral; and then drying in a vacuum drying oven at 50-70℃ for 8-12 hours to obtain carboxylated nitrogen-doped mesoporous carbon.

9. The method for preparing the photoresponsive wastewater treatment agent according to claim 9, characterized in that, In the method for preparing carboxylated nitrogen-doped mesoporous carbon, the average length of the nitrogen-doped mesoporous carbon is 1 μm, and the specific surface area is ≥350 m². 2 / g, pore size approximately 4.83nm, nitrogen content approximately 6.7at.

10. A photoresponsive wastewater treatment agent, characterized in that, It is prepared by the method for preparing the photoresponsive wastewater treatment agent according to any one of claims 1-9.

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