Cyanuric acid wastewater resource utilization treatment method

Abstract

The invention discloses a cyanuric acid wastewater resource utilization treatment method, and relates to the technical field of organic wastewater treatment.The cyanuric acid wastewater resource utilization treatment method is characterized by comprising the steps that the pH value and salt concentration of cyanuric acid-containing wastewater are adjusted, a precipitation reaction is performed at normal temperature till solid-liquid separation is performed, clear liquid and sodium cyanurate filter residues are obtained, and the sodium cyanurate filter residues are recycled; and carrying out suction filtration treatment on the clear liquid by using special resin to obtain suction filtration produced water, and treating the special resin subjected to suction filtration treatment by using regenerated liquid flow to obtain regenerated waste liquid and recycling the regenerated waste liquid. The method has the effects that sodium cyanurate is efficiently recycled, and a high-salt matrix is synchronously constructed to directly meet the requirements of ionic membrane raw materials; the special resin is high in adsorption capacity and regeneration efficiency, and regenerated waste liquid is recycled; the total nitrogen removal rate and the TOC removal rate are high after deep treatment of the electro-catalysis process, and the energy consumption is remarkably reduced compared with that of a traditional process; the resource utilization treatment method is free of secondary pollution, and the treatment cost is remarkably reduced compared with that of a traditional process.

Description

Technical Field

[0001] The present invention relates to the technical field of organic wastewater treatment, and more particularly to a method for resource utilization and treatment of cyanuric acid wastewater. Background Art

[0002] Chloroisocyanuric acid compounds (such as trichloroisocyanuric acid and dichloroisocyanuric acid) are highly effective, broad-spectrum disinfectants and bleaching agents, widely used in public health, water treatment, and industrial circulating cooling water systems. However, the cyanuric acid wastewater generated during their production process is characterized by complex composition, high salinity, high chemical oxygen demand, and high total nitrogen content, creating a technical bottleneck that hinders the sustainable development of the industry. Traditional treatment methods (such as CN104803531B) use direct oxidation with sodium hypochlorite, which requires excessive addition of oxidant, resulting in high treatment costs and long reaction cycles. Furthermore, the introduction of excessive sulfate ions far exceeds the standard for brine refining by ion-exchange membrane electrolysis, significantly increasing the subsequent impurity removal load.

[0003] Chloroisocyanuric acid production and the chlor-alkali industry are naturally intertwined. The former produces cyanuric acid-containing wastewater, while the latter requires high-purity sodium chloride brine to produce caustic soda. However, traditional end-of-pipe treatment models suffer from two major limitations: low cyanuric acid recovery rates and the difficulty of salt purification. Membrane concentration processes produce concentrated water containing 1.5%-2.5% cyanuric acid, which still requires additional treatment, failing to form a closed-loop resource recovery chain.

[0004] Adsorption method is a key technology for deep purification. However, existing materials have many defects. Conventional styrene resins have a low adsorption capacity for cyanuric acid. They are easily contaminated by organic matter during long-term operation, and the adsorption capacity decays seriously.

[0005] With the advancement of the dual carbon goals, the traditional high-energy consumption and low-efficiency wastewater treatment model can no longer meet the needs of industrial upgrading, and there is an urgent need to develop a resource utilization and treatment method for cyanuric acid wastewater. Summary of the Invention

[0006] In view of the shortcomings of the prior art, the present invention aims to provide a method for resource utilization and treatment of cyanuric acid wastewater.

[0007] To achieve the above object, the present invention provides the following technical solutions:

[0008] A method for resource utilization of cyanuric acid wastewater, comprising the following steps:

[0009] (S01) Pretreatment

[0010] Adjusting the pH value and salt concentration of the cyanuric acid-containing wastewater, performing a precipitation reaction at room temperature until solid-liquid separation is achieved to obtain a clear liquid and a sodium cyanuric acid salt filter residue, and reusing the sodium cyanuric acid salt filter residue;

[0011] (S02) resin adsorption

[0012] The clear liquid is treated by suction filtration with a special resin to obtain suction filtration water, and the special resin after suction filtration is treated by regeneration liquid flow to obtain regeneration waste liquid and reuse;

[0013] The special resin is prepared by calcining carbon nanofibers modified with cerium nitrate, compounding with polystyrene microspheres, and then re-calcining the composites, followed by solvent extraction and drying.

[0014] (S03) Electrocatalytic treatment

[0015] The pH value of the water produced by resin filtration is adjusted to acidic, and TOC and nitrogen removal are carried out through electrocatalytic oxidation deep treatment.

[0016] In the above-mentioned scheme of the present invention, sodium chloride is added during the pretreatment step to, on the one hand, increase the sodium chloride concentration in the cyanuric acid wastewater to meet the brine requirements for ion-exchange membrane caustic soda; on the other hand, the solubility of sodium cyanurate salt is reduced through the salting-out effect, thereby reducing the processing load of subsequent processes. In the process setup, pretreatment and resin adsorption are first performed to allow most raw materials to be returned to production for use, improving resource utilization. Finally, electrocatalytic treatment is performed to not only remove organic matter and ammonia nitrogen through electrocatalytic oxidation, but also remove total nitrogen through electrocatalytic reduction, ensuring that the brine indicators meet the requirements of ion-exchange membrane electrolysis. The treatment process is clean: no waste is generated throughout the entire process, and all resources are utilized.

[0017] Preferably, in said (S01), the pH of the cyanuric acid-containing raw wastewater is adjusted to 7-9, preferably 8.5, using liquid alkali, the salt concentration is adjusted to 310±5 g / L using solid sodium chloride, and the precipitation reaction time is 1-2 h.

[0018] According to the above scheme of the present invention, the precipitation rate of sodium cyanurate reaches 98% under the preferred pH condition of 8.5, while avoiding equipment corrosion and by-product generation caused by excessively high pH.

[0019] Preferably, the suction filtration speed of the special resin in (S02) is 2-5BV / h, the flow rate of the special resin after the regeneration liquid flows through the suction filtration is 1-2BV / h, and during the flow, the temperature of the regeneration liquid is 40-70°C, and the volume of the regeneration liquid is 1-3BV; preferably, the suction filtration speed of the special resin in (S02) is 3-4BV / h, the flow rate of the special resin after the regeneration liquid flows through the suction filtration is 1-2BV / h, and during the flow, the temperature of the regeneration liquid is 50-60°C, and the volume of the regeneration liquid is 2BV;

[0020] Wherein, the regeneration liquid is 1-8wt% sodium hydroxide solution; preferably, the regeneration liquid is 3-6wt% sodium hydroxide solution;

[0021] In the step (S03), the pH value of the water produced by resin adsorption is adjusted to 3-5; preferably, the pH value of the water produced by resin adsorption is adjusted to 4 in the step (S03).

[0022] Preferably, the preparation method of the special resin in (S02) is as follows:

[0023] (S02-1) The cerium nitrate solution impregnated with carbon nanofibers is ultrasonically treated to obtain modified carbon nanofibers;

[0024] (S02-2) washing the modified carbon nanofibers until the pH is neutral and then calcining them in a tubular furnace under nitrogen protection to obtain a calcined product;

[0025] (S02-3) ball milling the calcined product, dispersant, and polystyrene microspheres to obtain a mixture, placing the mixture in a tube furnace under high-purity nitrogen protection, heating, maintaining the temperature, and cooling to room temperature to obtain a heat-treated product;

[0026] (S02-4) The heat-treated product is subjected to solvent extraction to obtain a solid product, which is then dried to obtain the special resin.

[0027] The above scheme of the present invention prepares a hierarchical pore structure resin with micropores, mesopores and macropores by compounding cerium nitrate-modified carbon nanofibers with polystyrene microspheres, which significantly enhances the specific surface area and improves the adsorption selectivity of cyanuric acid.

[0028] Preferably, the concentration of the cerium nitrate solution in (S02-1) is 0.05-0.15M, the solid-liquid mass ratio of the carbon nanofiber to the cerium nitrate solution is 1:(10-20), the ultrasonic treatment time of the cerium nitrate solution is 1-2h, the ultrasonic power is 200-300W, the frequency is 40-50kHz, and the ultrasonic temperature is 20-30℃; Preferably, the concentration of the cerium nitrate solution in (S02-1) is 0.08-0.12M, the solid-liquid mass ratio of the carbon nanofiber to the cerium nitrate solution is 1:(10-20), the ultrasonic treatment time of the cerium nitrate solution is 1-2h, the ultrasonic power is 200-300W, the frequency is 40-50kHz, and the ultrasonic temperature is 20-30℃. The mass ratio of carbon nanofiber to cerium nitrate solution is 1:(13-18), the ultrasonic treatment time of the cerium nitrate solution is 1.5h, the ultrasonic power is 220-280W, the frequency is 42-48kHz, and the ultrasonic temperature is 22-28°C; preferably, the concentration of the cerium nitrate solution in (S02-1) is 0.1M, the solid-liquid mass ratio of carbon nanofiber to cerium nitrate solution is 1:15, the ultrasonic treatment time of the cerium nitrate solution is 1.5h, the ultrasonic power is 250W, the frequency is 45kHz, and the ultrasonic temperature is 25°C.

[0029] In the above solution of the present invention, the solid-liquid mass ratio of carbon nanofiber to cerium nitrate solution is 1:(10-20) to ensure that cerium nitrate is evenly loaded on the fiber surface to form highly active Ce 4+The oxidation sites promote the chemical adsorption of cyanuric acid, and the ultrasonic treatment makes the cerium nitrate nanoparticles uniformly dispersed and the porosity improved, while avoiding the decomposition of the precursor caused by high temperature.

[0030] Preferably, the solid-liquid mass ratio of the carbon nanofibers to the cerium nitrate solution is 1:(14-16); preferably, the solid-liquid mass ratio of the carbon nanofibers to the cerium nitrate solution is 1:15.

[0031] Preferably, the modified carbon nanofibers in (S02-2) are washed with deionized water to a neutral pH, and calcined in a tubular furnace at 550-600°C for 1-3 hours with a heating rate of 4-6°C / min; preferably, the modified carbon nanofibers in (S02-2) are calcined in a tubular furnace at 580°C for 2 hours with a heating rate of 5°C / min.

[0032] Preferably, the calcined product and polystyrene microspheres in (S02-3) are mixed in a mass ratio of 1:(3-5), the amount of the dispersant added is 1-3% of the total mass of the calcined product and the polystyrene microspheres, and the dispersant is anhydrous ethanol; preferably, the calcined product and polystyrene microspheres in (S02-3) are mixed in a mass ratio of 1:4, the amount of the dispersant added is 2% of the total mass of the calcined product and the polystyrene microspheres, and the dispersant is anhydrous ethanol.

[0033] In the above scheme of the present invention, the calcined product is mixed with polystyrene microspheres in a mass ratio of 1:(3-5), which can optimize the balance between the mechanical strength and adsorption performance of the resin, improve the compressive strength, and reduce the adsorption capacity attenuation rate. In addition, anhydrous ethanol is used as a green dispersant to improve the uniformity of the mixture, effectively reduce agglomeration, and improve pore connectivity.

[0034] Preferably, the ball milling mixing time in (S02-3) is 30-60 min, the ball milling speed is 80-100 rpm, high-purity nitrogen is introduced into the tubular furnace in (S02-3), the flow rate is controlled to 100-200 mL / min, the temperature is raised to 800-900 ° C at a rate of 9-11 ° C / min and kept warm for 2-3 hours, and naturally cooled to room temperature under the protection of high-purity nitrogen; Preferably, the ball milling mixing time in (S02-3) is 40-50 min, the ball milling speed is 85-95 rpm, the tube furnace in (S02-3) is introduced with high-purity nitrogen, the flow rate is controlled to 100-200 mL / min, the temperature is raised to 800-900 ° C at a rate of 9-11 ° C / min and kept warm for 2-3 hours, and then naturally cooled to room temperature under the protection of high-purity nitrogen; Preferably, the ball milling mixing time in (S02-3) is 40-50 min, the ball milling speed is 85-95 rpm, and the tube furnace in (S02-3) is introduced with high-purity nitrogen, the flow rate is controlled to 100-200 mL / min, the temperature is raised to 800-900 ° C at a rate of 9-11 ° C / min and kept warm for 2-3 hours, and then naturally cooled to room temperature under the protection of high-purity nitrogen; High-purity nitrogen is introduced into the tubular furnace with a flow rate controlled at 120-180 mL / min, the temperature is increased to 820-880°C at a rate of 10°C / min and kept warm for 2-3 hours, and then naturally cooled to room temperature under the protection of high-purity nitrogen; preferably, the ball milling mixing time in (S02-3) is 45 minutes, the ball milling speed is 90 rpm, high-purity nitrogen is introduced into the tubular furnace in (S02-3), the flow rate is controlled at 150 mL / min, the temperature is increased to 850°C at a rate of 10°C / min and kept warm for 2-3 hours, and then naturally cooled to room temperature under the protection of high-purity nitrogen.

[0035] In the above solution of the present invention, the rotation speed of the ball mill is 80-100 rpm, which can achieve nano-scale composite of microspheres and fibers and optimize fluid mechanics performance.

[0036] Preferably, the heat-treated product in (S02-4) is placed in a Soxhlet extractor for solvent extraction, the extraction solvent is tetrahydrofuran, the extraction time is 10-14 hours, and the solid product is dried in a vacuum oven at 80-100°C for 10-16 hours; preferably, the heat-treated product in (S02-4) is placed in a Soxhlet extractor for solvent extraction, the extraction solvent is tetrahydrofuran, the extraction time is 11-13 hours, and the solid product is dried in a vacuum oven at 85-95°C for 11-15 hours; preferably, the heat-treated product in (S02-4) is placed in a Soxhlet extractor for solvent extraction, the extraction solvent is tetrahydrofuran, the extraction time is 12 hours, and the solid product is dried in a vacuum oven at 90°C for 12-14 hours.

[0037] In the above solution of the present invention, tetrahydrofuran selectively dissolves uncarbonized polystyrene, retains the multi-level pore structure, and improves the regeneration efficiency.

[0038] Preferably, the special resin has hierarchical pores of micropores, mesopores and macropores, and the mesopore diameter is 3-5 nm.

[0039] In the above solution of the present invention, the hierarchical pores realize the rapid diffusion and deep adsorption of cyanuric acid molecules, and the kinetic adsorption rate constant is large.

[0040] Preferably, the preparation method of the electrocatalytic electrode in (S03) is as follows:

[0041] (S03-1) acidifying the carbon nanotubes with a mixed acid, washing with deionized water until neutral, and then drying to obtain pretreated carbon nanotubes;

[0042] (S03-2) Tetraethyl titanate is dissolved in ethanol, and deionized water is added dropwise and stirred to obtain a titanium dioxide sol;

[0043] (S03-3) The pretreated carbon nanotubes are mixed with titanium dioxide sol and ultrasonically treated, and then polyethylene glycol is added and stirred at room temperature and aged. The gel is coated on the surface of conductive glass, dried, and then calcined in a muffle furnace to obtain the electrocatalytic electrode.

[0044] The above scheme of the present invention efficiently introduces carboxyl groups and sulfonic acid groups on the surface of carbon nanotubes through the synergistic oxidation of concentrated sulfuric acid, concentrated nitric acid and hydrogen peroxide, significantly improving their chemical bonding ability with titanium dioxide and significantly improving the interfacial binding energy; then, the hydrolysis conditions of tetraethyl titanate are optimized to prepare anatase-type titanium dioxide sol with uniform particle size, reducing the phase transition temperature during subsequent calcination and saving energy; finally, by optimizing the mass ratio of carbon nanotubes to titanium dioxide and the action of polyethylene glycol, a three-dimensional porous structure with a large specific surface area is formed, the mass transfer efficiency is improved, and the conductive network of the carbon nanotubes increases the electrode conductivity and the exposed proportion of catalytic active sites.

[0045] Preferably, the mixed acid in (S03-1) is a mixture of concentrated sulfuric acid, concentrated nitric acid and hydrogen peroxide in a volume ratio of 1:(1-3):1, and the carbon nanotubes in (S03-1) are washed with deionized water while the mixed acid is refluxed at 80°C for 4-6 hours.

[0046] In the above scheme of the present invention, concentrated sulfuric acid is used as the main oxidant to introduce carboxyl groups on the surface of carbon nanotubes, thereby increasing the surface polarity of carbon nanotubes. The addition of concentrated sulfuric acid can catalyze the oxidation of nitric acid and introduce sulfonic acid groups through a sulfonation reaction, thereby enhancing the hydrophilicity of carbon nanotubes. Hydrogen peroxide decomposes to produce hydroxyl radicals, which selectively oxidize defect sites in carbon nanotubes and synergistically enrich carboxyl groups with nitric acid, thereby enhancing the chemical bonding between carbon nanotubes and titanium dioxide. Hydrogen peroxide replaces part of the strong acid, significantly reducing the amount of nitric acid used and significantly reducing the concentration of nitrate ions in the waste acid, thereby reducing subsequent processing costs. At the same time, it can avoid the high corrosive risk of pure concentrated sulfuric acid systems and extend the service life of the reactor. In addition, the mild oxidation of hydrogen peroxide avoids the degradation of conductivity caused by excessive breakage of carbon nanotubes.

[0047] Preferably, the pretreated carbon nanotubes in (S03-2) are mixed with the titanium dioxide sol in a mass ratio of 1:(3-5), and the mixture in (S03-2) is stirred at a speed of 200-300 rpm for 1-2 hours; preferably, the pretreated carbon nanotubes in (S03-2) are mixed with the titanium dioxide sol in a mass ratio of 1:4, and the mixture in (S03-2) is stirred at a speed of 220-280 rpm for 1-2 hours.

[0048] In the above scheme of the present invention, the pretreated carbon nanotubes are mixed with the titanium dioxide sol in a mass ratio of 1:(3-5), ensuring that TiO2 fully wraps the carbon nanotubes and retains a certain porosity to promote mass transfer; at the same time, the electrode conductivity and the photocatalytic activity of titanium dioxide reach an optimal balance, promoting catalytic oxidation efficiency.

[0049] Preferably, the amount of polyethylene glycol added is 0.1-0.2 times the mass of the carbon nanotubes, the ultrasonic treatment in (S03-3) is 30-60 minutes, the stirring treatment is 1-2 hours, the aging treatment is 22-26 hours, and the muffle furnace is calcined at 400-500°C for 1-3 hours; preferably, the amount of polyethylene glycol added is 0.1-0.2 times the mass of the carbon nanotubes, the ultrasonic treatment in (S03-3) is 40-50 minutes, the stirring treatment is 1-2 hours, the aging treatment is 23-25 hours, and the muffle furnace is calcined at 420-480°C for 2 hours.

[0050] In the above scheme of the present invention, polyethylene glycol decomposes during calcination to form a mesoporous and macroporous composite structure, thereby increasing the specific surface area; at the same time, the polyethylene glycol chains wrap around the carbon nanotubes to prevent agglomeration during ultrasonic treatment, thereby improving the uniformity of carbon nanotube dispersion; and after the polyethylene glycol is pyrolyzed, a microporous skeleton is left behind, which can increase the hardness of the electrode and maintain a high catalytic activity.

[0051] Preferably, the current density of the electrocatalytic treatment in (S03) is 50-100 mA / cm 2 , preferably 55mA / cm 2 , oxidation time is 0.5-1h.

[0052] In the above solution of the present invention, the current density is 50-100 mA / cm 2 Within this range, the TOC degradation rate is faster, the electrode life is extended, and the comprehensive treatment cost is effectively controlled.

[0053] Compared with the prior art, the present invention has the following beneficial effects:

[0054] The present invention realizes the full resource utilization of raw wastewater containing cyanuric acid through a pretreatment-graded adsorption-electrocatalytic quality improvement synergistic process, with significant treatment efficiency and environmental benefits. First, the precipitation rate of sodium cyanuric acid salt under pH 8.5 conditions in the pretreatment step is improved, and a 310g / L high-salt matrix is simultaneously constructed, which not only recovers more than 95% of cyanuric acid, but also meets the ion-exchange membrane brine concentration requirements, reducing the subsequent processing load. Subsequently, a hierarchical pore resin prepared by blending and calcining cerium nitrate-modified carbon nanofibers and polystyrene is used to increase the adsorption capacity and regeneration efficiency. At the same time, the regenerated waste liquid is effectively reused, reducing alkali consumption. Finally, through the synergistic oxidation-reduction effect of carbon nanotube / titanium dioxide composite electrodes, the TOC removal rate and total nitrogen removal rate are both greater than 98%, which can be used as a raw material for ion-exchange membrane caustic soda. The treatment method realizes the full resource treatment of wastewater, and the treatment cost is significantly reduced compared with the traditional process. BRIEF DESCRIPTION OF THE DRAWINGS

[0055] Figure 1 This is a schematic diagram of the process flow of the resource utilization treatment method for cyanuric acid-containing wastewater proposed in the present invention;

[0056] Figure 2 This is a schematic diagram of a photo of raw water used in Example 1 of the present invention;

[0057] Figure 3 This is a schematic diagram of a water quality photograph of Example 1 of the present invention in which the pH value is adjusted to 3;

[0058] Figure 4 This is a schematic diagram of a water quality photograph obtained by electrocatalytic oxidation for 0.5 h according to Example 1 of the present invention;

[0059] Figure 5 This is a schematic diagram of a water quality photograph after electrocatalytic oxidation for 1 hour according to Example 1 of the present invention. DETAILED DESCRIPTION

[0060] A method for resource utilization of cyanuric acid wastewater, comprising the following steps:

[0061] (S01) Pretreatment

[0062] Adjusting the pH value and salt concentration of the cyanuric acid-containing wastewater, subjecting it to a precipitation reaction at room temperature until solid-liquid separation results in obtaining a clear liquid and a sodium cyanuric acid salt filter residue, which is then reused; in (S01), the pH of the cyanuric acid-containing raw wastewater is adjusted to 7-9 using liquid caustic soda, and the salt concentration is adjusted to 310±5 g / L using solid sodium chloride, and the precipitation reaction time is 1-2 hours;

[0063] (S02) resin adsorption

[0064] The clear liquid is treated by suction filtration with a special resin to obtain suction filtration water, and the special resin after suction filtration is treated by regeneration liquid flow to obtain regeneration waste liquid and reuse;

[0065] The special resin is made by calcining carbon nanofibers modified with cerium nitrate, then compounding with polystyrene microspheres and re-calcining, followed by solvent extraction and drying.

[0066] The suction filtration rate of the special resin in (S02) is 2-5BV / h, and the flow rate of the regeneration liquid after the special resin is 1-2BV / h. During the flow, the temperature of the regeneration liquid is 40-70°C, and the volume of the regeneration liquid is 1-3BV; wherein, the regeneration liquid is 1-8wt% sodium hydroxide solution;

[0067] The preparation method of the special resin in (S02) is as follows:

[0068] (S02-1) The cerium nitrate solution impregnated with carbon nanofibers is ultrasonically treated to obtain modified carbon nanofibers; the concentration of the cerium nitrate solution in (S02-1) is 0.05-0.15M, the solid-liquid mass ratio of the carbon nanofibers to the cerium nitrate solution is 1:(10-20), the ultrasonic treatment time of the cerium nitrate solution is 1-2h, the ultrasonic power is 200-300W, the frequency is 40-50kHz, and the ultrasonic temperature is 20-30°C; the solid-liquid mass ratio of the carbon nanofibers to the cerium nitrate solution is 1:(14-16);

[0069] (S02-2) The modified carbon nanofibers were washed to a neutral pH and then calcined in a tubular furnace under nitrogen protection to obtain a calcined product; (S02-2) The modified carbon nanofibers were washed with deionized water to a neutral pH and calcined in a tubular furnace at 550-600°C for 1-3h at a heating rate of 4-6°C / min

[0070] (S02-3) ball milling the calcined product, a dispersant, and polystyrene microspheres to obtain a mixture, placing the mixture in a tube furnace under high-purity nitrogen protection, heating, keeping the temperature, and cooling to room temperature to obtain a heat-treated product; in (S02-3), the calcined product and polystyrene microspheres are mixed in a mass ratio of 1:(3-5), and the amount of the dispersant added is 1-3% of the total mass of the calcined product and the polystyrene microspheres, and the dispersant is anhydrous ethanol;

[0071] (S02-3) The ball milling mixing time is 30-60 minutes, the ball milling speed is 80-100 rpm, and high-purity nitrogen is introduced into the tubular furnace in (S02-3) at a flow rate of 100-200 mL / min. The temperature is raised to 800-900°C at a rate of 9-11°C / min and kept at this temperature for 2-3 hours. The mixture is then naturally cooled to room temperature under the protection of high-purity nitrogen.

[0072] (S02-4) The heat-treated product is subjected to solvent extraction to obtain a solid product, which is then dried to obtain a special resin. The heat-treated product in (S02-4) is placed in a Soxhlet extractor for solvent extraction using tetrahydrofuran for 10-14 hours. The solid product is dried in a vacuum oven at 80-100°C for 10-16 hours. The special resin has hierarchical pores of micropores, mesopores, and macropores, with the mesopore diameter being 3-5 nm.

[0073] (S03) Electrocatalytic treatment

[0074] Adjust the pH value of the resin filtration water to acidic, and remove TOC and denitrify by electrocatalytic oxidation deep treatment; the current density of the electrocatalytic treatment in (S03) is 50-100mA / cm 2 , the oxidation time is 0.5-1h; (S03) adjusting the pH value of the resin adsorption water to 3-5;

[0075] The preparation method of the electrocatalytic electrode in (S03) is as follows:

[0076] (S03-1) acidifying the carbon nanotubes with a mixed acid, washing with deionized water until neutral, and then drying to obtain pretreated carbon nanotubes; wherein the mixed acid in (S03-1) is a mixture of concentrated sulfuric acid, concentrated nitric acid, and hydrogen peroxide in a volume ratio of 1:(1-3):1, and wherein the carbon nanotubes in (S03-1) are refluxed at 75-85° C. for 4-6 hours with the mixed acid, and then washed with deionized water;

[0077] (S03-2) Tetraethyl titanate is dissolved in ethanol, and deionized water is added dropwise and stirred to obtain a titanium dioxide sol; the pretreated carbon nanotubes in (S03-2) are mixed with the titanium dioxide sol in a mass ratio of 1:(3-5), and the mixture in (S03-2) is stirred at a speed of 200-300 rpm for 1-2 hours;

[0078] (S03-3) The pretreated carbon nanotubes are mixed with a titanium dioxide sol and ultrasonically treated, followed by the addition of polyethylene glycol, stirring at room temperature, and aging. The gel is coated on a conductive glass surface, dried, and calcined in a muffle furnace to obtain an electrocatalytic electrode. The amount of polyethylene glycol added is 0.1-0.2 times the mass of the carbon nanotubes. In (S03-3), the mixture is ultrasonically treated for 30-60 minutes, stirred for 1-2 hours, aged for 22-26 hours, and calcined in a muffle furnace at 400-500°C for 1-3 hours.

[0079] Reference Figures 1 to 5 shown.

[0080] Example 1

[0081] A method for resource utilization of cyanuric acid wastewater, comprising the following steps:

[0082] Take the raw cyanuric acid wastewater, first add liquid alkali to adjust the pH to 8.5, then add sodium chloride salt to make the brine concentration reach 310g / L, stir and precipitate at room temperature for 2h and then filter. The filtered clear liquid is removed from the resin adsorption treatment and treated with a single-stage resin tower with a filtration rate of 2BV / h. The resin is a special resin. After adsorption of 40BV, it reaches the adsorption end point. A 4% sodium hydroxide solution is used, the temperature is 50℃, the regeneration flow rate is 1BV / h, and the total volume of regeneration liquid consumed is 2BV. Hydrochloric acid is added to the resin adsorption water to adjust the pH to 3, and then electrocatalytic treatment is carried out with a current density of 55mA / cm 2 The reaction was stopped after 1 h of oxidation.

[0083] Among them, the preparation method of special resin is as follows:

[0084] (S02-1) The carbon nanofibers were immersed in a 0.1 M cerium nitrate solution to make the solid-liquid mass ratio 1:15, and ultrasonically treated for 1.5 h at an ultrasonic power of 250 W, a frequency of 45 kHz, and an ultrasonic temperature of 25°C.

[0085] (S02-2) The washed carbon nanofibers were then rinsed with deionized water until the pH was neutral. The washed carbon nanofibers were placed in a tubular furnace under nitrogen protection and calcined at 570°C for 2 h at a heating rate of 5°C / min.

[0086] (S02-3) The calcined product was mixed with polystyrene microspheres in a mass ratio of 1:4, and anhydrous ethanol (2% of the total mass of the calcined product and the polystyrene microspheres) was added, and the mixture was mixed in a ball mill for 45 minutes at a speed of 90 rpm. The blended mixture was placed in a tube furnace, and high-purity nitrogen was introduced at a flow rate of 150 mL / min. The temperature was raised to 850°C at a rate of 10°C / min and kept at this temperature for 2.5 hours. The mixture was allowed to cool naturally to room temperature under the protection of high-purity nitrogen.

[0087] (S02-4) The cooled mixture was placed in a Soxhlet extractor for solvent extraction using tetrahydrofuran for 12 hours. The mixture was then placed in a vacuum oven and dried at 90°C for 14 hours to obtain a special resin.

[0088] The preparation method of the electrocatalytic electrode in (S03) is as follows:

[0089] (S03-1) acidifying the carbon nanotubes with a mixed acid, wherein the mixed acid is a mixture of concentrated sulfuric acid, concentrated nitric acid, and hydrogen peroxide in a volume ratio of 1:2:1, refluxing at 80° C. for 5 hours, washing with deionized water until neutral, and then drying to obtain pretreated carbon nanotubes;

[0090] (S03-2) Tetraethyl titanate was dissolved in ethanol, deionized water was added dropwise, and the mixture was stirred at 250 rpm for 1.5 h to obtain a titanium dioxide sol;

[0091] (S03-3) The pretreated carbon nanotubes were mixed with titanium dioxide sol in a mass ratio of 1:4 and ultrasonically treated for 45 minutes. Then, polyethylene glycol (0.15 times the mass of the carbon nanotubes) was added and stirred at room temperature for 1.5 hours. The mixture was then aged for 24 hours. The gel was coated on the surface of conductive glass, dried, placed in a muffle furnace, and calcined at 450°C for 2 hours to obtain an electrocatalytic electrode.

[0092] TOC and TN were measured for the water produced at each stage of the treatment process in Example 1. TOC was determined according to HJ501-2009, Water Quality - Determination of Total Organic Carbon (Determination of Total Organic Carbon) by Combustion Oxidation-Non-Dispersive Infrared Absorption Method, using a Shimadzu TOC-L instrument. The error range was ±3%. Each sample was replicated three times, with the average value taken. TN was determined according to HJ636-2012, Water Quality - Determination of Total Nitrogen by Alkaline Potassium Persulfate Digestion-UV Spectrophotometry Method, using a HACHDR6000 UV-Vis Spectrophotometer. The error range was ±5%. Each sample was replicated three times, with the average value taken. The specific experimental results are shown in the table below.

[0093] Serial number name TOC (mg / L) TN (mg / L) 1 Raw wastewater 564 358 2 Pre-treated water 95 113 3 Resin adsorption water production 12.6 18 4 Electrocatalytic water production 6.5 3.2

[0094] Example 2

[0095] During the preparation of the special resin, the solid-liquid mass ratio of the carbon nanofibers to the cerium nitrate solution was 1:10, and the remaining steps were consistent with Example 1.

[0096] TOC and TN were measured for the water produced at each stage of the treatment process in Example 2. TOC was determined according to HJ501-2009, Water Quality - Determination of Total Organic Carbon (Determination of Total Organic Carbon) by Combustion Oxidation-Non-Dispersive Infrared Absorption Method, using a Shimadzu TOC-L instrument. The error range was ±3%. Each sample was replicated three times, with the average value taken. TN was determined according to HJ636-2012, Water Quality - Determination of Total Nitrogen by Alkaline Potassium Persulfate Digestion-UV Spectrophotometry Method, using a HACHDR6000 UV-Vis Spectrophotometer. The error range was ±5%. Each sample was replicated three times, with the average value taken. The specific experimental results are shown in the table below.

[0097] Serial number name TOC (mg / L) TN (mg / L) 1 Raw wastewater 564 358 2 Pre-treated water 95 113 3 Resin adsorption water production 13.9 20.1 4 Electrocatalytic water production 7.2 5.9

[0098] Example 3

[0099] During the preparation of the special resin, the solid-liquid mass ratio of the carbon nanofibers to the cerium nitrate solution was 1:20, and the remaining steps were consistent with Example 1.

[0100] TOC and TN were measured for the water produced at each stage of the treatment process in Example 3. TOC was determined according to HJ501-2009, Water Quality - Determination of Total Organic Carbon (Determination of Total Organic Carbon) by Combustion Oxidation-Non-Dispersive Infrared Absorption Method, using a Shimadzu TOC-L instrument. The error range was ±3%. Each sample was replicated three times, with the average value taken. TN was determined according to HJ636-2012, Water Quality - Determination of Total Nitrogen by Alkaline Potassium Persulfate Digestion-UV Spectrophotometry Method, using a HACHDR6000 UV-Vis Spectrophotometer. The error range was ±5%. Each sample was replicated three times, with the average value taken. The specific experimental results are shown in the table below.

[0101] Serial number name TOC (mg / L) TN (mg / L) 1 Raw wastewater 564 358 2 Pre-treated water 95 113 3 Resin adsorption water production 14.7 22.0 4 Electrocatalytic water production 8.4 7.5

[0102] Example 4

[0103] During the preparation of the special resin, the calcined product was mixed with polystyrene microspheres at a mass ratio of 1:3, and the remaining steps were the same as in Example 1.

[0104] TOC and TN were measured for the water produced at each stage of the treatment process in Example 4. TOC was determined according to HJ501-2009, Water Quality - Determination of Total Organic Carbon (Determination of Total Organic Carbon) by Combustion Oxidation-Non-Dispersive Infrared Absorption Method, using a Shimadzu TOC-L instrument. The error range was ±3%. Each sample was replicated three times, and the average value was calculated. TN was determined according to HJ636-2012, Water Quality - Determination of Total Nitrogen by Alkaline Potassium Persulfate Digestion-UV Spectrophotometry Method, using a HACHDR6000 UV-Vis Spectrophotometer. The error range was ±5%. Each sample was replicated three times, and the average value was calculated. The specific experimental results are shown in the table below.

[0105] Serial number name TOC (mg / L) TN (mg / L) 1 Raw wastewater 564 358 2 Pre-treated water 95 113 3 Resin adsorption water production 13.1 19.2 4 Electrocatalytic water production 6.8 3.8

[0106] Example 5

[0107] During the preparation of the special resin, the calcined product was mixed with polystyrene microspheres at a mass ratio of 1:5, and the remaining steps were the same as in Example 1.

[0108] TOC and TN were measured for the water produced at each stage of the treatment process in Example 5. TOC was determined according to HJ501-2009, Water Quality - Determination of Total Organic Carbon - Combustion Oxidation-Non-Dispersive Infrared Absorption Method, using a Shimadzu TOC-L instrument. The error range was ±3%. Each sample was replicated three times, with the average value taken. TN was determined according to HJ636-2012, Water Quality - Determination of Total Nitrogen - Alkaline Potassium Persulfate Digestion - UV Spectrophotometry Method, using a HACHDR6000 UV-Vis Spectrophotometer. The error range was ±5%. Each sample was replicated three times, with the average value taken. The specific experimental results are shown in the table below.

[0109] Serial number name TOC (mg / L) TN (mg / L) 1 Raw wastewater 564 358 2 Pre-treated water 95 113 3 Resin adsorption water production 13.7 18.6 4 Electrocatalytic water production 7.1 4.0

[0110] Example 6

[0111] During the preparation of the electrocatalytic electrode, the carbon nanotubes pretreated with S11-3 were mixed with the titanium dioxide sol in a mass ratio of 1:3, and the remaining steps were consistent with Example 1.

[0112] TOC and TN were measured for the water produced at each treatment stage in Example 6. TOC was determined according to HJ501-2009, Water Quality - Determination of Total Organic Carbon (Determination of Total Organic Carbon) by Combustion Oxidation-Non-Dispersive Infrared Absorption Method, using a Shimadzu TOC-L instrument. The error range was ±3%. Each sample was replicated three times, with the average value taken. TN was determined according to HJ636-2012, Water Quality - Determination of Total Nitrogen by Alkaline Potassium Persulfate Digestion-UV Spectrophotometry Method, using a HACHDR6000 UV-Vis Spectrophotometer. The error range was ±5%. Each sample was replicated three times, with the average value taken. The specific experimental results are shown in the table below.

[0113] Serial number name TOC (mg / L) TN (mg / L) 1 Raw wastewater 564 358 2 Pre-treated water 95 113 3 Resin adsorption water production 12.6 18 4 Electrocatalytic water production 6.9 3.6

[0114] Example 7

[0115] During the preparation of the electrocatalytic electrode, the carbon nanotubes pretreated with S11-3 were mixed with the titanium dioxide sol in a mass ratio of 1:5, and the remaining steps were consistent with Example 1.

[0116] TOC and TN were measured for the water produced at each stage of the treatment process in Example 7. TOC was determined according to HJ501-2009, Water Quality - Determination of Total Organic Carbon (Determination of Total Organic Carbon) by Combustion Oxidation-Non-Dispersive Infrared Absorption Method, using a Shimadzu TOC-L instrument. The error range was ±3%. Each sample was replicated three times, and the average value was calculated. TN was determined according to HJ636-2012, Water Quality - Determination of Total Nitrogen by Alkaline Potassium Persulfate Digestion-UV Spectrophotometry Method, using a HACHDR6000 UV-Vis Spectrophotometer. The error range was ±5%. Each sample was replicated three times, and the average value was calculated. The specific experimental results are shown in the table below.

[0117] Serial number name TOC (mg / L) TN (mg / L) 1 Raw wastewater 564 358 2 Pre-treated water 95 113 3 Resin adsorption water production 12.6 18 4 Electrocatalytic water production 6.6 3.5

[0118] Example 8

[0119] During the preparation of the electrocatalytic electrode, the amount of S11-3 polyethylene glycol added was 0.1 times the mass of the carbon nanotubes, and the remaining steps were consistent with Example 1.

[0120] TOC and TN were measured for the water produced at each stage of the treatment process in Example 8. TOC was determined according to HJ501-2009, Water Quality - Determination of Total Organic Carbon - Combustion Oxidation-Non-Dispersive Infrared Absorption Method, using a Shimadzu TOC-L instrument. The error range was ±3%. Each sample was replicated three times, with the average value taken. TN was determined according to HJ636-2012, Water Quality - Determination of Total Nitrogen - Alkaline Potassium Persulfate Digestion - UV Spectrophotometry Method, using a HACHDR6000 UV-Vis Spectrophotometer. The error range was ±5%. Each sample was replicated three times, with the average value taken. The specific experimental results are shown in the table below.

[0121] Serial number name TOC (mg / L) TN (mg / L) 1 Raw wastewater 564 358 2 Pre-treated water 95 113 3 Resin adsorption water production 12.6 18 4 Electrocatalytic water production 7.1 3.3

[0122] Example 9

[0123] During the preparation of the electrocatalytic electrode, the amount of S11-3 polyethylene glycol added was 0.2 times the mass of the carbon nanotubes, and the remaining steps were consistent with Example 1.

[0124] TOC and TN were measured for the water produced at each stage of the treatment process in Example 9. TOC was measured according to HJ501-2009, Water Quality - Determination of Total Organic Carbon - Combustion Oxidation-Non-Dispersive Infrared Absorption Method, using a Shimadzu TOC-L instrument. The error range was ±3%. Each sample was replicated three times, with the average value taken. TN was measured according to HJ636-2012, Water Quality - Determination of Total Nitrogen - Alkaline Potassium Persulfate Digestion UV Spectrophotometry Method, using a HACHDR6000 UV-Vis Spectrophotometer. The error range was ±5%. Each sample was replicated three times, with the average value taken. The specific experimental results are shown in the table below.

[0125] Serial number name TOC (mg / L) TN (mg / L) 1 Raw wastewater 564 358 2 Pre-treated water 95 113 3 Resin adsorption water production 12.6 18 4 Electrocatalytic water production 6.8 3.2

[0126] Comparative Example 1

[0127] No NaCl was added during the pretreatment stage, and the solution was filtered directly after adjusting the pH to 8.5. The remaining steps were the same as those in Example 1.

[0128] The TOC and TN of the produced water at different treatment stages of Comparative Example 1 were measured, and the specific experimental results are shown in the following table.

[0129] Serial number name TOC (mg / L) TN (mg / L) 1 Raw wastewater 564 358 2 Pre-treated water 216 281 3 Resin adsorption water production 46.5 86.9 4 Electrocatalytic water production 19.8 26.5

[0130] Comparative Example 2

[0131] Conventional styrene resin was used in the resin adsorption stage, which was purchased from Shanghai Yuanye Biotechnology Co., Ltd. The remaining steps were the same as those in Example 1.

[0132] The TOC and TN of the produced water at different treatment stages of Comparative Example 2 were measured, and the specific experimental results are shown in the following table.

[0133] Serial number name TOC (mg / L) TN (mg / L) 1 Raw wastewater 564 358 2 Pre-treated water 95 113 3 Resin adsorption water production 38.4 57.3 4 Electrocatalytic water production 12.6 15.2

[0134] Comparative Example 3

[0135] The preparation process of the special resin does not add cerium nitrate, and the remaining steps are consistent with Example 1.

[0136] The TOC and TN of the produced water at different treatment stages of Comparative Example 3 were measured, and the specific experimental results are shown in the following table.

[0137] Serial number name TOC (mg / L) TN (mg / L) 1 Raw wastewater 564 358 2 Pre-treated water 95 113 3 Resin adsorption water production 52.0 64.1 4 Electrocatalytic water production 18.3 32.6

[0138] Comparative Example 4

[0139] The preparation process of the special resin does not include the addition of polystyrene microspheres, and the remaining steps are consistent with those of Example 1.

[0140] The TOC and TN of the produced water at different treatment stages of Comparative Example 4 were measured, and the specific experimental results are shown in the following table.

[0141] Serial number name TOC (mg / L) TN (mg / L) 1 Raw wastewater 564 358 2 Pre-treated water 95 113 3 Resin adsorption water production 63.2 58.9 4 Electrocatalytic water production 32.7 26.5

[0142] Comparative Example 5

[0143] In the preparation process of the special resin (S3-2), no anhydrous ethanol is added, and the remaining steps are the same as those in Example 1.

[0144] The TOC and TN of the produced water at different treatment stages of Comparative Example 5 were measured, and the specific experimental results are shown in the following table.

[0145] Serial number name TOC (mg / L) TN (mg / L) 1 Raw wastewater 564 358 2 Pre-treated water 95 113 3 Resin adsorption water production 42.1 53.6 4 Electrocatalytic water production 16.9 19.8

[0146] Comparative Example 6

[0147] Untreated carbon nanofibers were used instead of the special resin, and the remaining steps were consistent with those in Example 1.

[0148] The TOC and TN of the produced water at different treatment stages of Comparative Example 6 were measured, and the specific experimental results are shown in the following table.

[0149] Serial number name TOC (mg / L) TN (mg / L) 1 Raw wastewater 564 358 2 Pre-treated water 95 113 3 Resin adsorption water production 78.3 83.9 4 Electrocatalytic water production 42.3 49.6

[0150] Comparative Example 7

[0151] In the preparation of the electrocatalytic electrode, hydrogen peroxide was not added to the mixed acid, and the remaining steps were the same as in Example 1.

[0152] The TOC and TN of the produced water at different treatment stages of Comparative Example 7 were measured, and the specific experimental results are shown in the following table.

[0153] Serial number name TOC (mg / L) TN (mg / L) 1 Raw wastewater 564 358 2 Pre-treated water 95 113 3 Resin adsorption water production 12.6 18 4 Electrocatalytic water production 7.6 4.5

[0154] Comparative Example 8

[0155] Polyethylene glycol was not added during the preparation of the electrocatalytic electrode, and the remaining steps were the same as those in Example 1.

[0156] The TOC and TN of the produced water at different treatment stages of Comparative Example 8 were measured, and the specific experimental results are shown in the following table.

[0157] Serial number name TOC (mg / L) TN (mg / L) 1 Raw wastewater 564 358 2 Pre-treated water 95 113 3 Resin adsorption water production 12.6 18 4 Electrocatalytic water production 6.9 3.5

[0158] Comparative Example 9

[0159] Titanium dioxide sol was not added during the preparation of the electrocatalytic electrode, and the remaining steps were the same as those in Example 1.

[0160] The TOC and TN of the produced water at different treatment stages of Comparative Example 9 were measured, and the specific experimental results are shown in the following table.

[0161] Serial number name TOC (mg / L) TN (mg / L) 1 Raw wastewater 564 358 2 Pre-treated water 95 113 3 Resin adsorption water production 12.6 18 4 Electrocatalytic water production 9.1 11.3

[0162] Comparative Example 10

[0163] In the preparation of the electrocatalytic electrode, the carbon nanotubes were not subjected to acidification treatment, and the remaining steps were the same as those in Example 1.

[0164] The TOC and TN of the produced water at different treatment stages of Comparative Example 10 were measured, and the specific experimental results are shown in the following table.

[0165] Serial number name TOC (mg / L) TN (mg / L) 1 Raw wastewater 564 358 2 Pre-treated water 95 113 3 Resin adsorption water production 12.6 18 4 Electrocatalytic water production 8.2 7.5

[0166] The above experimental data show that the pretreatment stage significantly reduced the TOC and TN content of the wastewater by adjusting the pH and adding sodium chloride for precipitation reaction. This step effectively removed most of the organic matter and nitrogen pollutants, laying a good foundation for subsequent treatment. The selective adsorption of the dedicated resin in the resin adsorption stage deeply purified the organic matter and nitrogen pollutants in the wastewater, further removing TOC and TN in the wastewater. As the final treatment step, the electrocatalytic treatment stage effectively decomposed the difficult-to-degrade organic matter. At the same time, the electrocatalytic action removed the residual nitrogen pollutants, reduced the TOC and TN content of the wastewater, and ensured that the water quality met the standards for brine used in ion membrane electrolysis.

[0167] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, rather than to limit it. Although the present invention has been described in detail with reference to the aforementioned embodiments, those skilled in the art should understand that they can still modify the technical solutions described in the aforementioned embodiments, or make equivalent replacements for some of the technical features therein. However, these modifications or replacements do not deviate the essence of the corresponding technical solutions from the spirit and scope of the technical solutions of the various embodiments of the present invention.

Claims

1. A method for resource utilization of cyanuric acid wastewater, characterized by: The method comprises the following steps, (S01) Pretreatment Adjusting the pH value and salt concentration of the cyanuric acid-containing wastewater, performing a precipitation reaction at room temperature until solid-liquid separation is achieved to obtain a clear liquid and a sodium cyanuric acid salt filter residue, and reusing the sodium cyanuric acid salt filter residue; (S02) resin adsorption The clear liquid is treated by suction filtration with a special resin to obtain suction filtration water, and the special resin after suction filtration is treated by regeneration liquid flow to obtain regeneration waste liquid and reuse; The special resin is prepared by calcining carbon nanofibers modified with cerium nitrate, compounding with polystyrene microspheres, and then re-calcining the composites, followed by solvent extraction and drying. (S03) Electrocatalytic treatment The pH value of the water produced by resin filtration is adjusted to acidic, and TOC and nitrogen removal are carried out through electrocatalytic oxidation deep treatment.

2. The method for resource utilization of cyanuric acid wastewater according to claim 1, wherein: In (S01), the pH of the cyanuric acid-containing raw wastewater is adjusted to 7-9 using liquid alkali, the salt concentration is adjusted to 310±5 g / L using solid sodium chloride, and the precipitation reaction time is 1-2 hours; The suction filtration rate of the special resin in (S02) is 2-5 BV / h, the flow rate of the special resin after the regeneration liquid flows through the suction filtration is 1-2 BV / h, and during the flow process, the temperature of the regeneration liquid is 40-70°C, and the volume of the regeneration liquid is 1-3 BV; Wherein, the regeneration liquid is 1-8wt% sodium hydroxide solution; In the step (S03), the pH value of the water produced by resin adsorption is adjusted to 3-5.

3. The method for resource utilization of cyanuric acid wastewater according to claim 1, wherein: The preparation method of the special resin in (S02) is as follows: (S02-1) The cerium nitrate solution impregnated with carbon nanofibers is ultrasonically treated to obtain modified carbon nanofibers; (S02-2) washing the modified carbon nanofibers until the pH is neutral and then calcining them in a tubular furnace under nitrogen protection to obtain a calcined product; (S02-3) ball milling the calcined product, dispersant, and polystyrene microspheres to obtain a mixture, placing the mixture in a tube furnace under high-purity nitrogen protection, heating, maintaining the temperature, and cooling to room temperature to obtain a heat-treated product; (S02-4) The heat-treated product is subjected to solvent extraction to obtain a solid product, which is then dried to obtain the special resin.

4. The method for resource utilization of cyanuric acid wastewater according to claim 3, characterized in that: The concentration of the cerium nitrate solution in (S02-1) is 0.05-0.15M, the solid-liquid mass ratio of the carbon nanofiber to the cerium nitrate solution is 1:(10-20), the ultrasonic treatment time of the cerium nitrate solution is 1-2h, the ultrasonic power is 200-300W, the frequency is 40-50kHz, and the ultrasonic temperature is 20-30°C; The solid-liquid mass ratio of the carbon nanofiber to the cerium nitrate solution is 1:(14-16).

5. The method for resource utilization of cyanuric acid wastewater according to claim 3, characterized in that: The modified carbon nanofibers in (S02-2) are washed with deionized water until the pH is neutral, and calcined in a tubular furnace at 550-600°C for 1-3 hours at a heating rate of 4-6°C / min; The calcined product in (S02-3) is mixed with polystyrene microspheres in a mass ratio of 1:(3-5), and the added amount of the dispersant is 1-3% of the total mass of the calcined product and the polystyrene microspheres. The dispersant is anhydrous ethanol.

6. The method for resource utilization of cyanuric acid wastewater according to claim 3, characterized in that: The ball milling mixing time in (S02-3) is 30-60 min, the ball milling speed is 80-100 rpm, high-purity nitrogen is introduced into the tubular furnace in (S02-3), the flow rate is controlled at 100-200 mL / min, the temperature is increased to 800-900°C at a rate of 9-11°C / min and kept at this temperature for 2-3 hours, and then naturally cooled to room temperature under the protection of high-purity nitrogen; The heat-treated product in (S02-4) is placed in a Soxhlet extractor for solvent extraction, the extraction solvent is tetrahydrofuran, and the extraction time is 10-14 hours. The solid product is dried in a vacuum oven at 80-100°C for 10-16 hours.

7. The method for resource utilization of cyanuric acid wastewater according to claim 1, characterized in that: The preparation method of the electrocatalytic electrode in (S03) is as follows: (S03-1) acidifying the carbon nanotubes with a mixed acid, washing with deionized water until neutral, and then drying to obtain pretreated carbon nanotubes; (S03-2) Tetraethyl titanate is dissolved in ethanol, and deionized water is added dropwise and stirred to obtain a titanium dioxide sol; (S03-3) The pretreated carbon nanotubes are mixed with titanium dioxide sol and ultrasonically treated, and then polyethylene glycol is added and stirred at room temperature and aged. The gel is coated on the surface of conductive glass, dried, and then calcined in a muffle furnace to obtain the electrocatalytic electrode.

8. The method for resource utilization of cyanuric acid wastewater according to claim 7, characterized in that: The mixed acid in (S03-1) is a mixture of concentrated sulfuric acid, concentrated nitric acid and hydrogen peroxide in a volume ratio of 1:(1-3):

1. The carbon nanotubes in (S03-1) are refluxed at 75-85° C. for 4-6 hours and then washed with deionized water.

9. The method for resource utilization of cyanuric acid wastewater according to claim 7, characterized in that: The pretreated carbon nanotubes in (S03-2) are mixed with the titanium dioxide sol in a mass ratio of 1:(3-5), and the mixture in (S03-2) is stirred at a speed of 200-300 rpm for 1-2 hours.

10. The method for resource utilization of cyanuric acid wastewater according to claim 7, characterized in that: The amount of polyethylene glycol added is 0.1-0.2 times the mass of the carbon nanotubes. In the step (S03-3), the ultrasonic treatment is performed for 30-60 minutes, the stirring treatment is performed for 1-2 hours, the aging treatment is performed for 22-26 hours, and the muffle furnace is calcined at 400-500° C. for 1-3 hours.

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