A purification process for hydrazine-containing industrial wastewater
By loading cobalt and copper ions onto mesoporous silica to form a composite catalyst with a gradient pore structure, the problem of low decomposition efficiency of unsymmetrical dimethylhydrazine at low concentrations was solved, achieving a highly efficient wastewater treatment effect.
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Patents(China)
- Current Assignee / Owner
- SHAANXI DAMEI CHEM TECH CO LTD
- Filing Date
- 2026-03-23
- Publication Date
- 2026-05-26
AI Technical Summary
In existing technologies, when treating hydrazine-containing industrial wastewater, the concentration of unsymmetrical dimethylhydrazine decreases as the reaction proceeds, and the catalyst cannot effectively enrich unsymmetrical dimethylhydrazine, resulting in a low decomposition rate and difficulty in meeting the effluent requirements.
A composite catalyst is employed, which consists of cobalt and copper ions supported on mesoporous silica. A gradient pore structure is formed by inner and outer coating liquids. The inner and outer shells use an organic-inorganic hybrid structure formed by the hydrolysis products of TEOS and VTMS and acrylic acid as a framework. The inner walls of the pores in the inner and outer shells contain carboxyl groups, which enrich unsymmetrical dimethylhydrazine (UDMH) through electrostatic interaction and synergistically work with hydrogen peroxide to improve the concentration of UDMH near the active site and the utilization rate of hydrogen peroxide.
The concentration of unsymmetrical dimethylhydrazine in wastewater was effectively reduced within the hydraulic retention time, meeting effluent requirements and improving the utilization rate of hydrogen peroxide and the decomposition rate of unsymmetrical dimethylhydrazine.
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Abstract
Description
Technical Field
[0001] This invention belongs to the field of wastewater treatment technology, and in particular relates to a treatment process for hydrazine-containing industrial wastewater. Background Technology
[0002] In industrial applications, the production of methylhydrazine using the hydrazine hydrochloride-methanol method often results in wastewater containing unsymmetrical dimethylhydrazine (UDMH). UDMH is highly toxic and volatile, easily causing air, water, and soil pollution, and therefore requires decomposition and removal. Wastewater containing UDMH at a concentration of less than 0.5 mg / L meets effluent requirements.
[0003] Chinese patent document CN105036289B discloses a method for degrading high-concentration unsymmetrical dimethylhydrazine (UDMH) wastewater, comprising the following steps: preparing a mixed solution of tetraethyl orthosilicate, anhydrous ethanol, and deionized water; adding solid ferric nitrate to the mixed solution and stirring to dissolve; adjusting the pH with dilute nitric acid; refluxing with diethanolamine for 2-8 hours; drying the solution in an oven to form a dry gel; calcining the dry gel to obtain nano-iron-based SiO2; grinding the nano-iron-based SiO2 to obtain a powdered solid; immersing the nano-iron-based SiO2 powdered solid in one of rhenium, rhodium, and cerium salts dissolved in anhydrous ethanol to form a suspension; stirring the suspension to coat the Fe surface with rhenium, rhodium, and cerium; drying the suspension; and calcining the suspension to obtain a nano-sandwich structured iron-based catalyst. When the above catalyst and hydrogen peroxide synergistically treat wastewater containing UDMH, the catalyst can catalyze the generation of hydroxyl radicals from hydrogen peroxide. The hydroxyl radicals can break the N-N and CN bonds in the UDMH molecule to generate small molecules such as carbon dioxide, effectively degrading UDMH.
[0004] However, as the reaction continues, the concentration of unsymmetrical dimethylhydrazine (UDMH) in the wastewater decreases, and the number of UDMH molecules per unit volume decreases. The catalyst does not have a structure that selectively enriches UDMH, which leads to a significant decrease in the probability of UDMH colliding with hydroxyl radicals. Hydroxyl radicals are easily quenched before encountering UDMH, hydrogen peroxide is wasted, and the decomposition rate of UDMH is low. Within the specified hydraulic retention time, the concentration of UDMH is prone to continuously exceeding the standard, failing to meet the effluent requirements. Summary of the Invention
[0005] This invention provides a purification process for hydrazine-containing industrial wastewater. The process uses a composite catalyst and hydrogen peroxide to treat the wastewater. The composite catalyst can rapidly enrich unsymmetrical dimethylhydrazine (UDMH) in the wastewater and continuously transfer it to the active sites. It maintains high treatment efficiency even when the UDMH concentration decreases, effectively reducing the concentration of UDMH in the wastewater within a specified hydraulic retention time to meet effluent requirements.
[0006] A purification process for hydrazine-containing industrial wastewater includes the following steps:
[0007] S1. Cobalt and copper ions are loaded onto mesoporous silica and calcined to obtain composite microparticles.
[0008] S2. Polyethylene glycol hexadecyl ether was dissolved in an ethanol solution and the pH was adjusted. TEOS and VTMS were added to react, and acrylic acid and an initiator were added and mixed to obtain an inner coating solution. Poloxamer was dissolved in an ethanol solution and the pH was adjusted. TEOS and VTMS were added to react, and acrylic acid and an initiator were added and mixed to obtain an outer coating solution. The composite microparticles were subjected to hydroxylation treatment and then dispersed in the inner coating solution and heated to react. After extraction and washing, they were dispersed in the outer coating solution and heated to react. After extraction, washing, and drying, the composite catalyst was obtained.
[0009] S3. Adjust the pH value of the hydrazine-containing industrial wastewater, mix it with hydrogen peroxide solution and composite catalyst to obtain low-hydrazine effluent, thus completing the purification treatment of the hydrazine-containing industrial wastewater.
[0010] This invention employs a composite catalyst and hydrogen peroxide solution to synergistically treat industrial wastewater containing unsymmetrical dimethylhydrazine. The composite catalyst, from the inside out, comprises composite microparticles, an inner shell layer prepared using an inner coating liquid, and an outer shell layer prepared using an outer coating liquid. The composite microparticles contain active sites composed of copper and cobalt oxides. Both the inner and outer shell layers utilize an organic-inorganic hybrid structure formed by the hydrolysis products of TEOS (tetraethyl orthosilicate) and VTMS (vinyltrimethoxysilane) and acrylic acid as a framework. The inner shell layer contains pores formed after the in-situ removal of the pore-forming agent polyethylene glycol hexadecyl ether, while the outer shell layer contains pores formed after the in-situ removal of the pore-forming agent poloxamer, whose molecular size is larger than polyethylene glycol hexadecyl ether. This creates a gradient pore structure on the composite microparticles with pore size decreasing from the outside to the inside, reducing... The mass transfer resistance of wastewater facilitates the rapid penetration of composite microparticles, accelerating wastewater treatment efficiency. Because acrylic acid participates in the construction of the inner and outer shell skeletal structures, and the pore walls of these layers contain carboxyl groups, they can effectively enrich unsymmetrical dimethylhydrazine (UDMH) in wastewater through electrostatic interactions. Under the influence of the concentration gradient, UDMH continuously diffuses towards the active sites, increasing the concentration of UDMH near the active sites. Even if the concentration of UDMH in the wastewater decreases, it still ensures efficient collision between hydroxyl radicals generated from hydrogen peroxide catalyzed by the active sites and UDMH, improving the utilization rate of hydrogen peroxide and the decomposition rate of UDMH. This reduces the UDMH content in the wastewater within the specified hydraulic retention time, meeting effluent requirements.
[0011] Further, in step S1, the mesoporous silica is modified with aminosilane and then dispersed in a precursor solution. The mixture is heated to 70-75°C and reacted for 4-5 hours, then allowed to stand for aging for 12-14 hours. After filtration, it is washed with deionized water and anhydrous ethanol and dried in an environment of 55-60°C and 20-25 kPa for 8-10 hours. It is then placed in a nitrogen atmosphere and calcined at 300-310°C for 2-3 hours, cooled to 70-80°C, and the nitrogen is replaced with air. The mixture is then calcined at 300-310°C for 25-30 minutes and cooled to obtain composite microparticles. The precursor solution is obtained by dissolving copper nitrate, cobalt nitrate, and glucose in deionized water.
[0012] Furthermore, mesoporous silica was modified with aminosilane in the following manner: 90-95 wt% ethanol solution was mixed with APTES, acetic acid solution was added dropwise to adjust the pH to 5-6, the reaction was allowed to proceed for 2-3 hours, mesoporous silica was added and dispersed, the reaction was allowed to proceed for 3-4 hours, the mixture was filtered, and the silica was washed with anhydrous ethanol and deionized water to complete the aminosilane modification of the mesoporous silica.
[0013] Mesoporous silica was modified using APTES (3-aminopropyltriethoxysilane) to introduce primary amino groups onto the mesoporous silica, providing a molecular basis for the subsequent binding of cobalt and copper ions through coordination and other processes to form active sites through subsequent oxidation.
[0014] Furthermore, the composite microparticles comprise the following raw materials in parts by weight: 48-53 parts mesoporous silica, 9-11 parts APTES, and 300-310 parts precursor solution; the precursor solution is prepared by dissolving 8-10 parts by weight of copper nitrate, 2-3 parts by weight of cobalt nitrate, and 2-3 parts by weight of glucose in 300-320 parts by weight of deionized water.
[0015] Furthermore, during the preparation of the inner coating solution, polyethylene glycol hexadecyl ether is dissolved in a 50-60 wt% ethanol solution, hydrochloric acid is added dropwise to adjust the pH value to 5.5-6, TEOS and VTMS are added and mixed, and the reaction is carried out for 1-1.5 hours; the average molecular weight of the polyethylene glycol hexadecyl ether is 1100-1150 g / mol.
[0016] Furthermore, in the preparation of the outer coating solution, poloxamer is dissolved in a 30-40 wt% ethanol solution, hydrochloric acid is added dropwise to adjust the pH value to 5.5-6, TEOS and VTMS are added and mixed well, and the reaction is carried out for 2-3 hours to obtain the outer coating solution.
[0017] Under weakly acidic conditions with a pH of 5.5-6, TEOS and VTMS undergo controlled hydrolysis and initial condensation to generate silicon-oxygen oligomers with increased size. By adjusting the reaction time, the size of the silicon-oxygen oligomers can be controlled, making it difficult for them to penetrate into the mesopores of the composite microparticles or the pores of the inner shell due to steric hindrance, thus preventing mesopore and pore blockage and improving mass transfer efficiency.
[0018] Further, in step S2, the composite microparticles are dispersed in a 5-7 wt% ammonium fluoride solution and reacted for 12-15 min. After washing, the composite microparticles are enriched with hydroxyl groups. Then, they are dispersed in an inner coating solution and heated to 40-45℃ for 6-7 h, then to 60-65℃ for 4-5 h. After washing, they are dispersed in a 20-30 wt% ethanol solution and extracted at 78-80℃ for 7-8 h. After washing, they are dispersed in an outer coating solution and heated to 40-45℃ for 6-7 h, then to 60-65℃ for 4-5 h. After washing, they are dispersed in a 30-40 wt% ethanol solution and extracted at 78-80℃ for 10-12 h. After washing, they are dried at 50-60℃ and 8-10 kPa for 10-12 h to obtain the composite catalyst. The washing liquid is anhydrous ethanol and / or deionized water.
[0019] After etching with a 5-7 wt% ammonium fluoride solution, silanol groups are reintroduced onto the surface of the composite microparticles. These microparticles are then dispersed in an inner coating solution. TEOS and VTMS in the inner coating solution hydrolyze under acidic conditions. Condensation reactions occur between the hydrolysis products and between the hydrolysis products and the silanol groups on the surface of the composite microparticles. Initiated by an initiator, the VTMS hydrolysis products undergo free radical polymerization with the carbon-carbon double bonds of acrylic acid, forming an organic-inorganic hybrid framework templated with polyethylene glycol hexadecyl ether. At 78-80°C, polyethylene glycol hexadecyl ether diffuses into a 20-30 wt% ethanol solution under a concentration gradient and forms pores in situ. An inner shell is formed on the composite microparticles and then dispersed in the outer coating solution. Condensation reactions occur between the hydrolysis products of TEOS and VTMS, and between the hydrolysis products and the silanol groups of the inner shell. Free radical polymerization reactions occur between the hydrolysis products of VTMS and the carbon-carbon double bonds of acrylic acid, forming an organic-inorganic hybrid framework with poloxamer as a template. Under the action of a concentration gradient, poloxamer can diffuse into a 30-40wt% ethanol solution and form pores in situ, forming an outer shell on the inner shell. The composite microparticles, inner shell, and outer shell are connected by covalent bonds, resulting in a stable structure and good long-term stability of the composite catalyst.
[0020] Furthermore, in step S2, the hydroxylated composite microparticles are dispersed in the inner coating solution and reacted at 40-45℃ for 6-7 hours, then cooled to 15-20℃ and dissolved by adding NH4HCO3; the microparticles are also dispersed in the outer coating solution and reacted at 40-45℃ for 6-7 hours, then cooled to 15-20℃ and dissolved by adding NH4HCO3.
[0021] After the hydroxylated composite microparticles are mixed with the inner coating solution, they are reacted at 40-45℃ for 6-7 hours. The organic-inorganic hybrid framework is initially formed and is in a wet gel state. After cooling, NH4HCO3 is added to dissolve the microparticles. The NH4HCO3 molecules diffuse into the wet gel and decompose at 60-65℃ to generate ammonia and carbon dioxide. This generates microbubble disturbance in the wet gel, inhibiting excessive densification of the organic-inorganic hybrid framework. This makes it easier for polyethylene glycol hexadecyl ether to diffuse outward under the action of the concentration gradient, improving the porosity and pore connectivity of the inner shell layer and preventing the subsequent continuous leakage of polyethylene glycol hexadecyl ether from affecting the COD of the effluent. Similarly, it can also improve the porosity and pore connectivity of the outer shell layer.
[0022] Furthermore, the composite catalyst comprises the following raw materials in parts by weight: 28-33 parts composite microparticles, 160-170 parts inner coating liquid, 160-170 parts outer coating liquid, and 0-6 parts NH4HCO3; the inner coating liquid comprises the following raw materials in parts by weight: 9-12 parts polyethylene glycol hexadecyl ether, 300-320 parts 50-60wt% ethanol solution, 13-16 parts TEOS, 7-9 parts VTMS, 8-10 parts acrylic acid, and 0.1-0.2 parts initiator V-50; the outer coating liquid comprises the following raw materials in parts by weight: 5-7 parts poloxamer, 300-320 parts 30-40wt% ethanol solution, 10-12 parts TEOS, 6-8 parts VTMS, 7-9 parts acrylic acid, and 0.1-0.2 parts initiator V-50.
[0023] Furthermore, in step S3, the composite catalyst is packed into the column of the fixed bed. After adjusting the pH of the hydrazine-containing industrial wastewater to 6-7 with sodium hydroxide, it is simultaneously introduced into the fixed bed along with a 5-7 wt% hydrogen peroxide solution at a mass ratio of (25-27):1. The liquid flow rate in the fixed bed is controlled at 1.5-2 BV / h to obtain low-hydrazine effluent, thus completing the purification treatment of the hydrazine-containing industrial wastewater.
[0024] The present invention has the following beneficial effects:
[0025] This invention provides a purification process for hydrazine-containing industrial wastewater. The process utilizes a composite catalyst and hydrogen peroxide solution to treat the wastewater. The composite catalyst comprises composite microparticles, an inner shell, and an outer shell. The composite microparticles are loaded with copper oxide and cobalt oxide as active sites. Both the inner and outer shells use an organic-inorganic hybrid structure formed by the hydrolysis products of TEOS and VTMS and acrylic acid as a framework. The inner shell contains small-diameter pores formed in situ after the removal of polyethylene glycol hexadecyl ether, while the outer shell contains large-diameter pores formed in situ after the removal of poloxamer. This creates a gradient pore structure with decreasing pore size from the outside to the inside, facilitating rapid wastewater penetration. Due to the introduction of acrylic acid, the inner walls of the pores contain carboxyl groups, allowing the pores to accumulate unsymmetrical dimethylhydrazine (UDMH) through electrostatic interactions and continuously diffuse towards the active sites. Even when the UDMH concentration in the wastewater decreases, the concentration near the active sites remains high, improving the utilization rate of hydrogen peroxide and the degradation rate of UDMH. This effectively removes UDMH from the wastewater within a specified hydraulic retention time, meeting effluent standards. Detailed Implementation
[0026] Preparation Example 1
[0027] Add 8g copper nitrate, 3g cobalt nitrate, and 2g glucose to 300g deionized water and stir at 500rpm for 15min to obtain the precursor solution; add 10g of [unspecified ingredient] to 250g 90wt% ethanol solution. APTES (3-aminopropyltriethoxysilane) was stirred at 500 rpm for 10 min, and the pH was adjusted to 5 by adding 10 wt% acetic acid solution. The mixture was stirred at 300 rpm for 2 h, and 50 g of mesoporous silica with a particle size of 5 μm was added. The mixture was ultrasonically dispersed at 200 W for 20 min, stirred at 300 rpm for 3 h, filtered, washed three times with anhydrous ethanol, and washed three times with deionized water to complete the modification treatment of mesoporous silica. Then, it was added to 300 g of precursor solution, stirred at 1000 rpm for 20 min, heated to 70 °C, stirred at 400 rpm for 4 h, and allowed to stand for aging for 12 h. The mixture was filtered, washed four times with deionized water, and washed four times with anhydrous ethanol. It was dried in an environment of 55 °C and 20 kPa for 8 h, placed in a tube furnace, and calcined at 300 °C for 2 h under nitrogen protection. The temperature was lowered to 80 °C, the nitrogen was replaced with air, and the temperature was raised to 300 °C for 30 min. The mixture was then naturally cooled to room temperature to obtain composite microparticles.
[0028] Preparation Example 2
[0029] Add 10g copper nitrate, 2.6g cobalt nitrate, and 2.5g glucose to 310g deionized water and stir at 500rpm for 15min to obtain a precursor solution; add 11g of [unspecified ingredient] to 255g 92wt% ethanol solution. APTES was stirred at 500 rpm for 10 min, and 10 wt% acetic acid solution was added dropwise to adjust the pH to 5.5. The mixture was stirred at 300 rpm for 2.5 h, and 53 g of mesoporous silica with a particle size of 5 μm was added. The mixture was ultrasonically dispersed at 200 W for 20 min, stirred at 300 rpm for 3.5 h, filtered, washed three times with anhydrous ethanol, and washed three times with deionized water to complete the modification treatment of mesoporous silica. Then, it was added to 306 g of precursor solution, stirred at 1000 rpm for 20 min, heated to 75 °C, stirred at 400 rpm for 4.5 h, and allowed to stand for aging for 14 h. The mixture was filtered, washed four times with deionized water, and washed four times with anhydrous ethanol. It was dried in an environment of 58 °C and 23 kPa for 9 h, placed in a tube furnace, and calcined at 305 °C for 3 h under nitrogen protection. The temperature was lowered to 75 °C, the nitrogen was replaced with air, and the temperature was raised to 310 °C for calcination for 25 min. The mixture was then naturally cooled to room temperature to obtain composite microparticles.
[0030] Preparation Example 3
[0031] Add 9g copper nitrate, 2g cobalt nitrate, and 3g glucose to 320g deionized water and stir at 500rpm for 15min to obtain a precursor solution; add 9g of copper nitrate, 2g cobalt nitrate, and 3g glucose to 260g 95wt% ethanol solution. APTES was stirred at 500 rpm for 10 min, and 10 wt% acetic acid solution was added dropwise to adjust the pH to 6. The mixture was stirred at 300 rpm for 3 h, and 48 g of mesoporous silica with a particle size of 5 μm was added. The mixture was ultrasonically dispersed at 200 W for 20 min, stirred at 300 rpm for 4 h, filtered, washed three times with anhydrous ethanol, and washed three times with deionized water to complete the modification treatment of mesoporous silica. Then, it was added to 310 g of precursor solution, stirred at 1000 rpm for 20 min, heated to 72 °C, stirred at 400 rpm for 5 h, and allowed to stand for aging for 13 h. The mixture was filtered, washed four times with deionized water, and washed four times with anhydrous ethanol. It was dried in an environment of 60 °C and 25 kPa for 10 h, placed in a tube furnace, and calcined at 310 °C for 2.5 h under nitrogen protection. The temperature was lowered to 70 °C, the nitrogen was replaced with air, and the temperature was raised to 305 °C for calcination for 28 min. The mixture was then naturally cooled to room temperature to obtain composite microparticles.
[0032] Example 1
[0033] Add 9g of polyethylene glycol hexadecyl ether with an average molecular weight of 1100g / mol to 300g of 50wt% ethanol solution, stir at 500rpm for 30min, adjust the pH to 5.5 by adding 2wt% hydrochloric acid dropwise, add 13g of TEOS (tetraethyl orthosilicate) and 7g of VTMS (vinyltrimethoxysilane), stir at 800rpm for 10min, stir at 400rpm for 1h, add 8g of acrylic acid and 0.1g of V-50 (2,2'-azobis[2-(2-imidazolin-2-yl)propane] dihydrochloride), stir at 800rpm for 10min to obtain the inner coating solution; add 6g of poloxamer (preferably poloxamer 407) to 300g of 30wt% ethanol solution, stir at 500rpm for 50min, adjust the pH to 5.5 by adding 2wt% hydrochloric acid dropwise, add 10g of TEOS and 6g of... VTMS was stirred at 800 rpm for 10 min, then at 400 rpm for 2 h. 8 g of acrylic acid and 0.1 g of V-50 were added, and the mixture was stirred at 800 rpm for 10 min to obtain the outer coating solution.
[0034] 30g of composite microparticles were added to 400g of 5wt% ammonium fluoride solution and ultrasonically dispersed at 200W for 15min. The mixture was then filtered and washed with deionized water until the eluent was neutral, completing the hydroxylation treatment of the composite microparticles. Subsequently, the mixture was added to 160g of inner coating solution and stirred at 1000rpm for 20min. The temperature was raised to 40℃ and stirred at 300rpm for 6h. The temperature was lowered to 20℃, and 2g of NH4HCO3 (ammonium bicarbonate) was added. The mixture was stirred at 500rpm for 20min, raised to 60℃ and stirred at 300rpm for 4h. The mixture was filtered, washed three times with anhydrous ethanol, and three times with deionized water. The mixture was then added to 500g of... In a 20wt% ethanol solution, the mixture was stirred at 1000 rpm for 20 min, heated to 78℃, and refluxed at 300 rpm for 8 h. After filtration, the mixture was washed three times with deionized water and added to 160 g of the outer coating solution. The mixture was stirred at 1000 rpm for 20 min, heated to 40℃, and stirred at 300 rpm for 6 h. After cooling to 20℃, 2 g of NH4HCO3 was added, and the mixture was stirred at 500 rpm for 20 min, heated to 60℃, and stirred at 300 rpm for 4 h. After filtration, the mixture was washed three times with anhydrous ethanol and three times with deionized water. The mixture was then added to 500 g of a 30wt% ethanol solution, stirred at 1000 rpm for 20 min, heated to 78℃, and stirred at 500 rpm for 12 h. After filtration, the mixture was washed three times with deionized water and three times with anhydrous ethanol and dried at 50℃ and 10 kPa for 10 h to obtain the composite catalyst.
[0035] The composite catalyst was loaded into a fixed-bed column. Sodium hydroxide was added to the hydrazine-containing industrial wastewater to adjust the pH to 6. Then, it was simultaneously introduced into the fixed bed along with a 5wt% hydrogen peroxide solution at a mass ratio of 25:1. The liquid flow rate in the fixed bed was 2 BV / h, resulting in low-hydrazine effluent and completing the purification treatment of the hydrazine-containing industrial wastewater.
[0036] The composite microparticles used in this embodiment were prepared in Preparation Example 1.
[0037] Example 2
[0038] 9g of polyethylene glycol hexadecyl ether with an average molecular weight of 1100g / mol was added to 300g of 50wt% ethanol solution, stirred at 500rpm for 30min, and the pH was adjusted to 5.5 by adding 2wt% hydrochloric acid dropwise. 14g of TEOS and 7g of VTMS were added, and the mixture was stirred at 800rpm for 10min and then at 400rpm for 1h. 8g of acrylic acid and 0.1g of V-50 were added, and the mixture was stirred at 800rpm for 10min to obtain the inner coating solution. 6g of poloxamer (preferably poloxamer 407) was added to 300g of 30wt% ethanol solution, stirred at 500rpm for 50min, and the pH was adjusted to 5.5 by adding 2wt% hydrochloric acid dropwise. 10g of TEOS and 6g of VTMS were added, and the mixture was stirred at 800rpm for 10min and then at 400rpm for 2h. 8g of acrylic acid and 0.1g of V-50 were added, and the mixture was stirred at 800rpm for 10min to obtain the outer coating solution.
[0039] 28g of composite microparticles were added to 400g of 5wt% ammonium fluoride solution and ultrasonically dispersed at 200W for 15min. The mixture was filtered, washed with deionized water until the eluent was neutral, completing the hydroxylation treatment of the composite microparticles. Subsequently, the mixture was added to 160g of inner coating solution and stirred at 1000rpm for 20min. The temperature was raised to 40℃ and stirred at 300rpm for 6h. The temperature was lowered to 20℃, and 2.5g of NH4HCO3 (ammonium bicarbonate) was added. The mixture was stirred at 500rpm for 20min, raised to 60℃ and stirred at 300rpm for 4h. The mixture was filtered, washed three times with anhydrous ethanol, and three times with deionized water. The mixture was then added to 500g of... In a 20wt% ethanol solution, the mixture was stirred at 1000 rpm for 20 min, heated to 78℃, and refluxed at 300 rpm for 8 h. After filtration, the mixture was washed three times with deionized water and added to 165 g of the outer coating solution. The mixture was stirred at 1000 rpm for 20 min, heated to 40℃, and stirred at 300 rpm for 6 h. After cooling to 20℃, 2.3 g of NH4HCO3 was added, and the mixture was stirred at 500 rpm for 20 min, heated to 60℃, and stirred at 300 rpm for 4 h. After filtration, the mixture was washed three times with anhydrous ethanol and three times with deionized water. The mixture was added to 500 g of a 30wt% ethanol solution, stirred at 1000 rpm for 20 min, heated to 78℃, and stirred at 500 rpm for 12 h. After filtration, the mixture was washed three times with deionized water and three times with anhydrous ethanol and dried at 50℃ and 10 kPa for 10 h to obtain the composite catalyst.
[0040] The composite catalyst was loaded into a fixed-bed column. Sodium hydroxide was added to the hydrazine-containing industrial wastewater to adjust the pH to 6. Then, it was simultaneously introduced into the fixed bed along with a 5wt% hydrogen peroxide solution at a mass ratio of 25:1. The liquid flow rate in the fixed bed was 2 BV / h, resulting in low-hydrazine effluent and completing the purification treatment of the hydrazine-containing industrial wastewater.
[0041] The composite microparticles used in this embodiment were prepared in Preparation Example 1.
[0042] Example 3
[0043] 10g of polyethylene glycol hexadecyl ether with an average molecular weight of 1130g / mol was added to 310g of 55wt% ethanol solution, stirred at 500rpm for 30min, and the pH was adjusted to 5.7 by adding 2wt% hydrochloric acid dropwise. 15g of TEOS and 8g of VTMS were added, and the mixture was stirred at 800rpm for 10min and then at 400rpm for 1.5h. 9g of acrylic acid and 0.15g of V-50 were added, and the mixture was stirred at 800rpm for 10min to obtain the inner coating solution. 7g of poloxamer (preferably poloxamer 407) was added to 310g of 35wt% ethanol solution, stirred at 500rpm for 50min, and the pH was adjusted to 5.7 by adding 2wt% hydrochloric acid dropwise. 11g of TEOS and 8g of VTMS were added, and the mixture was stirred at 800rpm for 10min and then at 400rpm for 2.5h. 7g of acrylic acid and 0.15g of V-50 were added, and the mixture was stirred at 800rpm for 10min to obtain the outer coating solution.
[0044] 31g of composite microparticles were added to 400g of 6wt% ammonium fluoride solution and ultrasonically dispersed at 200W for 13min. The mixture was filtered, washed with deionized water until the eluent was neutral, completing the hydroxylation treatment of the composite microparticles. Subsequently, the mixture was added to 165g of inner coating solution and stirred at 1000rpm for 20min. The temperature was raised to 45℃ and stirred at 300rpm for 6.5h. The temperature was lowered to 20℃, and 2.4g of NH4HCO3 was added. The mixture was stirred at 500rpm for 20min, raised to 65℃ and stirred at 300rpm for 4.5h. The mixture was filtered, washed three times with anhydrous ethanol, and three times with deionized water. The mixture was then added to 500g of... In a 25wt% ethanol solution, the mixture was stirred at 1000 rpm for 20 min, heated to 80℃, and refluxed at 300 rpm for 7 h. After filtration, the mixture was washed three times with deionized water and added to 168 g of the outer coating solution. The mixture was stirred at 1000 rpm for 20 min, heated to 45℃, and stirred at 300 rpm for 7 h. After cooling to 18℃, 2.5 g of NH4HCO3 was added, and the mixture was stirred at 500 rpm for 20 min, heated to 65℃, and stirred at 300 rpm for 4.5 h. After filtration, the mixture was washed three times with anhydrous ethanol and three times with deionized water. The mixture was added to 500 g of a 35wt% ethanol solution, stirred at 1000 rpm for 20 min, heated to 79℃, and stirred at 500 rpm for 11 h. After filtration, the mixture was washed three times with deionized water and three times with anhydrous ethanol and dried at 60℃ and 9 kPa for 11 h to obtain the composite catalyst.
[0045] The composite catalyst was loaded into the column of a fixed bed. Sodium hydroxide was added to the hydrazine-containing industrial wastewater to adjust the pH to 6.5. Then, it was simultaneously introduced into the fixed bed along with a 6wt% hydrogen peroxide solution at a mass ratio of 26:1. The liquid flow rate in the fixed bed was 1.8 BV / h, resulting in low-hydrazine effluent and completing the purification treatment of the hydrazine-containing industrial wastewater.
[0046] The composite microparticles used in this embodiment were prepared in Preparation Example 2.
[0047] Example 4
[0048] 10g of polyethylene glycol hexadecyl ether with an average molecular weight of 1130g / mol was added to 310g of 55wt% ethanol solution, stirred at 500rpm for 30min, and the pH was adjusted to 5.7 by adding 2wt% hydrochloric acid dropwise. 15g of TEOS and 8g of VTMS were added, and the mixture was stirred at 800rpm for 10min and then at 400rpm for 1.5h. 9g of acrylic acid and 0.15g of V-50 were added, and the mixture was stirred at 800rpm for 10min to obtain the inner coating solution. 7g of poloxamer (preferably poloxamer 407) was added to 310g of 35wt% ethanol solution, stirred at 500rpm for 50min, and the pH was adjusted to 5.7 by adding 2wt% hydrochloric acid dropwise. 11g of TEOS and 8g of VTMS were added, and the mixture was stirred at 800rpm for 10min and then at 400rpm for 2.5h. 7g of acrylic acid and 0.15g of V-50 were added, and the mixture was stirred at 800rpm for 10min to obtain the outer coating solution.
[0049] 33g of composite microparticles were added to 400g of 6wt% ammonium fluoride solution and ultrasonically dispersed at 200W for 13min. The mixture was filtered, washed with deionized water until the eluent was neutral, completing the hydroxylation treatment of the composite microparticles. Subsequently, the mixture was added to 165g of inner coating solution and stirred at 1000rpm for 20min. The temperature was raised to 45℃ and stirred at 300rpm for 6.5h. The temperature was lowered to 20℃, and 2.8g of NH4HCO3 was added. The mixture was stirred at 500rpm for 20min, raised to 65℃ and stirred at 300rpm for 4.5h. The mixture was filtered, washed three times with anhydrous ethanol, and three times with deionized water. The mixture was then added to 500g of... In a 25 wt% ethanol solution, the mixture was stirred at 1000 rpm for 20 min, heated to 80 °C, and refluxed at 300 rpm for 7 h. After filtration, the mixture was washed three times with deionized water and added to 163 g of the outer coating solution. The mixture was stirred at 1000 rpm for 20 min, heated to 45 °C, and stirred at 300 rpm for 7 h. After cooling to 18 °C, 2.7 g of NH4HCO3 was added, and the mixture was stirred at 500 rpm for 20 min, heated to 65 °C, and stirred at 300 rpm for 4.5 h. After filtration, the mixture was washed three times with anhydrous ethanol and three times with deionized water. The mixture was added to 500 g of a 35 wt% ethanol solution, stirred at 1000 rpm for 20 min, heated to 79 °C, and stirred at 500 rpm for 11 h. After filtration, the mixture was washed three times with deionized water and three times with anhydrous ethanol and dried at 60 °C and 9 kPa for 11 h to obtain the composite catalyst.
[0050] The composite catalyst was loaded into the column of a fixed bed. Sodium hydroxide was added to the hydrazine-containing industrial wastewater to adjust the pH to 6.5. Then, it was simultaneously introduced into the fixed bed along with a 6wt% hydrogen peroxide solution at a mass ratio of 26:1. The liquid flow rate in the fixed bed was 1.8 BV / h, resulting in low-hydrazine effluent and completing the purification treatment of the hydrazine-containing industrial wastewater.
[0051] The composite microparticles used in this embodiment were prepared in Preparation Example 2.
[0052] Example 5
[0053] 12g of polyethylene glycol hexadecyl ether with an average molecular weight of 1150g / mol was added to 320g of 60wt% ethanol solution, stirred at 500rpm for 30min, and the pH was adjusted to 6 by adding 2wt% hydrochloric acid dropwise. 16g of TEOS and 9g of VTMS were added, and the mixture was stirred at 800rpm for 10min and then at 400rpm for 1.2h. 10g of acrylic acid and 0.2g of V-50 were added, and the mixture was stirred at 800rpm for 10min to obtain the inner coating solution. 5g of poloxamer (preferably poloxamer 407) was added to 320g of 40wt% ethanol solution, stirred at 500rpm for 50min, and the pH was adjusted to 6 by adding 2wt% hydrochloric acid dropwise. 12g of TEOS and 7g of VTMS were added, and the mixture was stirred at 800rpm for 10min and then at 400rpm for 3h. 9g of acrylic acid and 0.2g of V-50 were added, and the mixture was stirred at 800rpm for 10min to obtain the outer coating solution.
[0054] 32g of composite microparticles were added to 400g of 7wt% ammonium fluoride solution and ultrasonically dispersed at 200W for 12min. The mixture was filtered and washed with deionized water until the eluent was neutral, completing the hydroxylation treatment of the composite microparticles. Subsequently, the mixture was added to 170g of inner coating solution and stirred at 1000rpm for 20min. The temperature was raised to 42℃ and stirred at 300rpm for 7h. The temperature was lowered to 15℃, and 3g of NH4HCO3 was added. The mixture was stirred at 500rpm for 20min, raised to 63℃ and stirred at 300rpm for 5h. The mixture was filtered, washed three times with anhydrous ethanol, and three times with deionized water. The mixture was then added to 500g of... In a 30wt% ethanol solution, the mixture was stirred at 1000 rpm for 20 min, heated to 79℃, and refluxed at 300 rpm for 7.5 h. After filtration, the mixture was washed three times with deionized water and added to 170 g of the outer coating solution. The mixture was stirred at 1000 rpm for 20 min, heated to 42℃, and stirred at 300 rpm for 6.5 h. After cooling to 15℃, 3 g of NH4HCO3 was added, and the mixture was stirred at 500 rpm for 20 min, heated to 63℃, and stirred at 300 rpm for 5 h. After filtration, the mixture was washed three times with anhydrous ethanol and three times with deionized water. The mixture was then added to 500 g of a 40wt% ethanol solution, stirred at 1000 rpm for 20 min, heated to 79℃, and stirred at 500 rpm for 10 h. After filtration, the mixture was washed three times with deionized water and three times with anhydrous ethanol. The mixture was then dried at 55℃ and 8 kPa for 12 h to obtain the composite catalyst.
[0055] The composite catalyst was loaded into the column of a fixed bed. Sodium hydroxide was added to the hydrazine-containing industrial wastewater to adjust the pH to 7. Then, it was simultaneously introduced into the fixed bed along with a 7wt% hydrogen peroxide solution at a mass ratio of 27:1. The liquid flow rate in the fixed bed was 1.5 BV / h, resulting in low-hydrazine effluent and completing the purification treatment of the hydrazine-containing industrial wastewater.
[0056] The composite microparticles used in this embodiment were prepared in Preparation Example 3.
[0057] Example 6
[0058] 12g of polyethylene glycol hexadecyl ether with an average molecular weight of 1150g / mol was added to 320g of 60wt% ethanol solution, stirred at 500rpm for 30min, and the pH was adjusted to 6 by adding 2wt% hydrochloric acid dropwise. 16g of TEOS and 9g of VTMS were added, and the mixture was stirred at 800rpm for 10min and then at 400rpm for 1.2h. 10g of acrylic acid and 0.2g of V-50 were added, and the mixture was stirred at 800rpm for 10min to obtain the inner coating solution. 5g of poloxamer (preferably poloxamer 407) was added to 320g of 40wt% ethanol solution, stirred at 500rpm for 50min, and the pH was adjusted to 6 by adding 2wt% hydrochloric acid dropwise. 12g of TEOS and 7g of VTMS were added, and the mixture was stirred at 800rpm for 10min and then at 400rpm for 3h. 9g of acrylic acid and 0.2g of V-50 were added, and the mixture was stirred at 800rpm for 10min to obtain the outer coating solution.
[0059] 32g of composite microparticles were added to 400g of 7wt% ammonium fluoride solution and ultrasonically dispersed at 200W for 12min. The mixture was then filtered and washed with deionized water until the eluent was neutral, completing the hydroxylation treatment of the composite microparticles. Subsequently, the mixture was added to 170g of inner coating solution and stirred at 1000rpm for 20min. The temperature was raised to 42℃ and stirred at 300rpm for 7h. The temperature was then raised to 63℃ and stirred at 300rpm for 5h. The mixture was filtered, washed three times with anhydrous ethanol, and three times with deionized water. The mixture was then added to 500g of... In a 30wt% ethanol solution, the mixture was stirred at 1000 rpm for 20 min, heated to 79℃, and refluxed at 300 rpm for 7.5 h. After filtration, the mixture was washed three times with deionized water and added to 170 g of the outer coating solution. The mixture was stirred at 1000 rpm for 20 min, heated to 42℃, and stirred at 300 rpm for 6.5 h. After heating to 63℃, the mixture was stirred at 300 rpm for 5 h. After filtration, the mixture was washed three times with anhydrous ethanol and three times with deionized water. The mixture was added to 500 g of a 40wt% ethanol solution, stirred at 1000 rpm for 20 min, heated to 79℃, and stirred at 500 rpm for 10 h. After filtration, the mixture was washed three times with deionized water and three times with anhydrous ethanol and dried at 55℃ and 8 kPa for 12 h to obtain the composite catalyst.
[0060] The composite catalyst was loaded into the column of a fixed bed. Sodium hydroxide was added to the hydrazine-containing industrial wastewater to adjust the pH to 7. Then, it was simultaneously introduced into the fixed bed along with a 7wt% hydrogen peroxide solution at a mass ratio of 27:1. The liquid flow rate in the fixed bed was 1.5 BV / h, resulting in low-hydrazine effluent and completing the purification treatment of the hydrazine-containing industrial wastewater.
[0061] The composite microparticles used in this embodiment were prepared in Preparation Example 3.
[0062] The present invention also includes comparative examples and related experiments.
[0063] Comparative Example 1
[0064] The composite microparticles prepared in Example 5 were loaded into a column of a fixed bed. Sodium hydroxide was added to the hydrazine-containing industrial wastewater to adjust the pH to 7. Then, a 7wt% hydrogen peroxide solution was simultaneously introduced into the fixed bed at a mass ratio of 27:1. The liquid flow rate in the fixed bed was 1.5 BV / h, resulting in low-hydrazine effluent, thus completing the purification treatment of the hydrazine-containing industrial wastewater.
[0065] Comparative Example 2
[0066] The difference between this comparative example and Example 5 is that neither the inner nor outer coating liquid contains acrylic acid. The remaining operation steps and reaction conditions are the same as in Example 5, resulting in a composite catalyst and completing the purification treatment of hydrazine-containing industrial wastewater.
[0067] Comparative Example 3
[0068] The difference between this comparative example and Example 5 is that the composite particles were not treated with an outer coating liquid. The remaining operation steps and reaction conditions were the same as in Example 5, and a composite catalyst was obtained to complete the purification treatment of hydrazine-containing industrial wastewater.
[0069] Comparative Example 4
[0070] The difference between this comparative example and Example 5 is that the inner coating liquid was not used to treat the composite particles. The remaining operation steps and reaction conditions are the same as in Example 5, and a composite catalyst is obtained to complete the purification treatment of hydrazine-containing industrial wastewater.
[0071] Hydrazine-containing industrial wastewater treatment test
[0072] A solution of unsymmetrical dimethylhydrazine with a concentration of 5 mg / L and a COD value of 10.7 mg / L was prepared, and 10 wt% hydrochloric acid was added to adjust the pH value to 6. This solution was used to simulate hydrazine-containing industrial wastewater after pH adjustment. Take 30g of the composite catalysts prepared in each example and Comparative Examples 2 to 4, and pack them into the fixed-bed column tubes respectively. For Comparative Example 1, take 30g of the composite microparticles prepared in Example 5 and pack them into the fixed-bed column tubes. Hydrazine-containing industrial wastewater and 6wt% hydrogen peroxide solution are simultaneously introduced into each fixed bed at a mass ratio of 25:1. The liquid flow rate in each fixed bed is controlled at 2 BV / h to obtain low-hydrazine effluent. Effluent samples are collected on the 1st, 5th, 15th, 30th and 50th days after introduction. Catalase is added for treatment. The concentration of unsymmetrical dimethylhydrazine (mg / L) in the treated samples is detected by colorimetric spectrophotometry, and the COD value (mg / L) of the treated samples is detected by potassium dichromate method. The results are shown in Table 1.
[0073] Table 1
[0074]
[0075] As shown in Table 1, compared with Example 6, the content and COD value of unsymmetrical dimethylhydrazine (UDMH) in the low-hydrazine effluent obtained in Examples 1 to 5 were lower. This indicates that the addition of NH4HCO3 is beneficial to the complete removal of polyethylene glycol hexadecyl ether (PEG) and poloxamer, increases the porosity of the composite catalyst, accelerates mass transfer, and reduces the impact of continuously leaking PEG and poloxamer on the COD value of the effluent. Compared with Comparative Example 1, the content and COD value of UDMH in the low-hydrazine effluent obtained in Example 5 were lower. This indicates that when the UDMH concentration is low, the inner and outer shell layers can increase the concentration of UDMH near the active sites, thereby improving the removal efficiency of UDMH and effectively reducing the COD value within the specified hydraulic retention time. The concentration of unsymmetrical dimethylhydrazine (UDMH) in the wastewater meets the effluent requirements. Compared with Comparative Example 2, the UDMH content and COD value of the low-hydrazine effluent obtained in Example 5 are lower, indicating that the addition of acrylic acid can introduce carboxyl groups into the inner and outer shell layers, thereby enriching low-concentration UDMH and transferring it to the active sites, increasing the concentration of UDMH near the active sites. Compared with Comparative Examples 3 and 4, the UDMH content and COD value of the low-hydrazine effluent obtained in Example 5 are lower, indicating that in the composite catalyst, the inner and outer shell layers can synergistically construct a gradient pore structure with decreasing pore size from the outside to the inside, accelerating the mass transfer rate of wastewater, increasing the enrichment and treatment capacity of UDMH, and effectively reducing the UDMH content in wastewater.
Claims
1. A purification process for hydrazine-containing industrial wastewater, characterized in that, Includes the following steps: S1. Cobalt and copper ions are loaded onto mesoporous silica and calcined to obtain composite microparticles. S2. Polyethylene glycol hexadecyl ether was dissolved in an ethanol solution and the pH was adjusted. TEOS and VTMS were added to react, and acrylic acid and an initiator were added and mixed to obtain an inner coating solution. Poloxamer was dissolved in an ethanol solution and the pH was adjusted. TEOS and VTMS were added to react, and acrylic acid and an initiator were added and mixed to obtain an outer coating solution. The composite microparticles were subjected to hydroxylation treatment and then dispersed in the inner coating solution and heated to react. After extraction and washing, they were dispersed in the outer coating solution and heated to react. After extraction, washing, and drying, the composite catalyst was obtained. S3. Adjust the pH value of the hydrazine-containing industrial wastewater, mix it with hydrogen peroxide solution and composite catalyst to obtain low-hydrazine effluent, thus completing the purification treatment of the hydrazine-containing industrial wastewater.
2. The purification process for hydrazine-containing industrial wastewater according to claim 1, characterized in that, In step S1, mesoporous silica is modified with aminosilane and then dispersed in a precursor solution. The solution is heated to 70-75℃ and reacted for 4-5 hours. After standing and aging for 12-14 hours, the silica is filtered, washed with deionized water and anhydrous ethanol, and dried in an environment of 55-60℃ and 20-25kPa for 8-10 hours. The silica is then placed in a nitrogen atmosphere and calcined at 300-310℃ for 2-3 hours. The temperature is lowered to 70-80℃, the nitrogen is replaced with air, and the silica is calcined at 300-310℃ for 25-30 minutes. After cooling, composite microparticles are obtained. The precursor solution is obtained by dissolving copper nitrate, cobalt nitrate, and glucose in deionized water.
3. The purification process for hydrazine-containing industrial wastewater according to claim 2, characterized in that, The aminosilane modification of mesoporous silica was carried out by the following method: 90-95 wt% ethanol solution was mixed with APTES, acetic acid solution was added dropwise to adjust the pH to 5-6, and the reaction was carried out for 2-3 hours. Mesoporous silica was then added and dispersed, and the reaction was carried out for 3-4 hours. After filtration, the silica was washed with anhydrous ethanol and deionized water to complete the aminosilane modification of the mesoporous silica.
4. The purification process for hydrazine-containing industrial wastewater according to claim 3, characterized in that, The composite microparticles comprise the following raw materials in parts by weight: 48-53 parts mesoporous silica, 9-11 parts APTES, and 300-310 parts precursor solution; the precursor solution is prepared by dissolving 8-10 parts by weight of copper nitrate, 2-3 parts by weight of cobalt nitrate, and 2-3 parts by weight of glucose in 300-320 parts by weight of deionized water.
5. The purification process for hydrazine-containing industrial wastewater according to claim 1, characterized in that, In the preparation of the inner coating solution, polyethylene glycol hexadecyl ether is dissolved in a 50-60 wt% ethanol solution, hydrochloric acid is added dropwise to adjust the pH value to 5.5-6, TEOS and VTMS are added and mixed, and the reaction is carried out for 1-1.5 h; the average molecular weight of the polyethylene glycol hexadecyl ether is 1100-1150 g / mol.
6. The purification process for hydrazine-containing industrial wastewater according to claim 1, characterized in that, In the preparation of the outer coating solution, poloxamer is dissolved in a 30-40 wt% ethanol solution, hydrochloric acid is added dropwise to adjust the pH value to 5.5-6, TEOS and VTMS are added and mixed well, and the reaction is carried out for 2-3 hours to obtain the outer coating solution.
7. The purification process for hydrazine-containing industrial wastewater according to claim 1, characterized in that, In step S2, the composite microparticles are dispersed in a 5-7 wt% ammonium fluoride solution and reacted for 12-15 min. After washing, the composite microparticles are enriched with hydroxyl groups. Then, they are dispersed in an inner coating solution and heated to 40-45℃ for 6-7 h, then to 60-65℃ for 4-5 h. After washing, they are dispersed in a 20-30 wt% ethanol solution and extracted at 78-80℃ for 7-8 h. After washing, they are dispersed in an outer coating solution and heated to 40-45℃ for 6-7 h, then to 60-65℃ for 4-5 h. After washing, they are dispersed in a 30-40 wt% ethanol solution and extracted at 78-80℃ for 10-12 h. After washing, they are dried at 50-60℃ and 8-10 kPa for 10-12 h to obtain the composite catalyst. The washing liquid is anhydrous ethanol and / or deionized water.
8. The purification process for hydrazine-containing industrial wastewater according to claim 7, characterized in that, In step S2, the hydroxylated composite microparticles are dispersed in the inner coating solution and reacted at 40-45℃ for 6-7 hours. Then, the temperature is lowered to 15-20℃ and NH4HCO3 is added to dissolve them. After dispersing in the outer coating solution and reacting at 40-45℃ for 6-7 hours, the temperature is lowered to 15-20℃, and NH4HCO3 is added to dissolve it.
9. The purification process for hydrazine-containing industrial wastewater according to claim 1, characterized in that, The composite catalyst comprises the following raw materials in parts by weight: 28-33 parts composite microparticles, 160-170 parts inner coating liquid, 160-170 parts outer coating liquid, and 0-6 parts NH4HCO3. The inner coating liquid comprises the following raw materials in parts by weight: 9-12 parts polyethylene glycol hexadecyl ether, 300-320 parts 50-60 wt% ethanol solution, 13-16 parts TEOS, 7-9 parts VTMS, 8-10 parts acrylic acid, and 0.1-0.2 parts initiator V-50; the outer coating liquid comprises the following raw materials in parts by weight: 5-7 parts poloxamer, 300-320 parts 30-40 wt% ethanol solution, 10-12 parts TEOS, 6-8 parts VTMS, 7-9 parts acrylic acid, and 0.1-0.2 parts initiator V-50.
10. The purification process for hydrazine-containing industrial wastewater according to claim 1, characterized in that, In step S3, the composite catalyst is loaded into the column of a fixed bed. After adjusting the pH of the hydrazine-containing industrial wastewater to 6-7 with sodium hydroxide, it is simultaneously introduced into the fixed bed along with a 5-7 wt% hydrogen peroxide solution at a mass ratio of (25-27):
1. The liquid flow rate in the fixed bed is controlled at 1.5-2 BV / h to obtain low-hydrazine effluent, thus completing the purification treatment of the hydrazine-containing industrial wastewater.