Efficient decoloring agent for printing and dyeing wastewater and decoloring treatment method

Abstract

The application belongs to the technical field of water treatment, and particularly relates to a high-efficiency decoloring agent for printing and dyeing wastewater and a decoloring treatment method. A preparation method of the high-efficiency decoloring agent comprises the following steps: step (a), crushing and activating a magnetic zeolite to obtain an activated zeolite; step (b), modifying the activated zeolite to obtain a zinc-cobalt bimetallic modified zeolite matrix suspension; step (c), adding carbon-coated titanium dioxide nanoparticles into the zinc-cobalt bimetallic modified zeolite matrix suspension to obtain a zinc-cobalt bimetallic modified zeolite matrix loaded with the carbon-coated titanium dioxide nanoparticles; and step (d), performing surface in-situ polymerization grafting to obtain the high-efficiency decoloring agent for printing and dyeing wastewater. Through the synergistic effect of the zinc-cobalt bimetallic modified zeolite matrix, the pH-responsive polymer grafting layer and the carbon-coated titanium dioxide nanoparticles, and in combination with microwave-enhanced pretreatment and photocatalytic oxidation technology, the adsorption capacity and photocatalytic performance of the decoloring agent are significantly improved, and efficient recovery and recycling are realized.

Description

TECHNICAL FIELD

[0001] The present application belongs to the technical field of water treatment, and particularly relates to a high-efficiency decolorizing agent for printing and dyeing wastewater and a decolorizing treatment method. BACKGROUND

[0002] Printing and dyeing wastewater has become a big problem in the field of industrial wastewater treatment due to its complex composition, high colority, high concentration of organic pollutants, and significant biological toxicity. The chromophoric groups such as azo bond and anthraquinone structure in dye molecules have strong chemical stability, and traditional treatment methods such as coagulation sedimentation, adsorption and biodegradation often have difficulty in achieving efficient decolorization and organic matter removal. In addition, the existing technology often accompanies problems such as large sludge production, low resource utilization rate and secondary pollution in the treatment process, which further limits its application effect.

[0003] The commonly used decolorizing agents at present are mostly single-function inorganic or organic materials, such as iron salts, aluminum salts and modified activated carbon, etc., but these materials have the disadvantages of limited decolorization efficiency, poor adaptability and difficulty in recycling. Especially for high-concentration and refractory printing and dyeing wastewater, a single decolorizing agent often cannot meet the actual demand. At the same time, there is a lack of effective resource utilization means for sludge in the existing treatment process, resulting in increased sludge accumulation and disposal cost, further aggravating the environmental burden.

[0004] On the other hand, as a research hotspot in recent years, advanced oxidation technology can destroy the structure of dye molecules through strong oxidizing agents (such as ozone, hydrogen peroxide, etc.), but its operation cost is high, and it has strict requirements on reaction conditions (such as pH value, catalyst performance, etc.), making it difficult to realize large-scale promotion. In addition, the existing photoelectrocatalytic technology still has many challenges in electrode material selection, light energy utilization rate and system integration, which limits its application effect in actual engineering.

[0005] In view of the above problems, it is particularly important to develop a new type of decolorizing agent with high-efficiency decolorization ability, recyclable utilization characteristics and sludge resource potential and its matching treatment process. The ideal decolorizing agent should have the following characteristics: first, it can flexibly release active substances under different pH conditions to cope with the complex water quality changes of printing and dyeing wastewater; second, it has good magnetic recovery performance to reduce operation cost and reduce secondary pollution; third, it cooperates with other treatment units to realize deep purification and resource utilization of wastewater. The present application aims to solve the problems of low decolorization efficiency, sludge treatment difficulty and high operation cost in the existing technology, and provides a new solution for efficient treatment of printing and dyeing wastewater.

[0006] In summary, the printing and dyeing wastewater contains a large amount of refractory organic dyes and auxiliaries, and its decolorization treatment has been a difficult problem in the environmental protection field. Although the traditional decolorization methods such as coagulation and adsorption are simple to operate, they have problems such as low decolorization efficiency, large sludge production and secondary pollution. Therefore, it is of great significance to develop a high-efficiency, recyclable and environmentally friendly decolorizing agent and a supporting treatment method. SUMMARY

[0007] The present application relates to the technical field of wastewater treatment, and particularly relates to a printing and dyeing wastewater high-efficiency decolorizing agent and a decolorization treatment method thereof. Through the synergistic effect of a zinc-cobalt bimetal modified zeolite matrix, a pH responsive polymer grafting layer and carbon-coated titanium dioxide nanoparticles, combined with microwave enhanced pretreatment and photocatalytic oxidation technology, the adsorption capacity and photocatalytic performance of the decolorizing agent are significantly improved, and efficient recovery and recycling are realized.

[0008] The present application provides a printing and dyeing wastewater high-efficiency decolorizing agent, a preparation method thereof, which comprises the following steps:

[0009] Step (a): after the magnetic zeolite is crushed, the crushed magnetic zeolite is acid-activated in a 0.3-0.8 mol / L HCl solution at 50-70 DEG C for 1.5-2.5 h, washed and dried to obtain an activated zeolite;

[0010] Step (b): the activated zeolite is made into a 10-15% suspension, and 20-30% of zinc nitrate and cobalt nitrate by weight of the activated zeolite is added, and Zn:Co=1:2-4, and the mixture is reacted at 80-90 DEG C for 6-7 h to obtain a zinc-cobalt bimetal modified zeolite matrix suspension;

[0011] Step (c): carbon-coated titanium dioxide nanoparticles (zeolite:titanium dioxide mass ratio 10-15:1) are added to the zinc-cobalt bimetal modified zeolite matrix suspension, ultrasonic dispersion is performed for 20-30 min, and drying is performed to obtain a carbon-coated titanium dioxide nanoparticle loaded zinc-cobalt bimetal modified zeolite matrix;

[0012] Step (d): 1 part of the carbon-coated titanium dioxide nanoparticle loaded zinc-cobalt bimetal modified zeolite matrix is added to 3-5 parts of a 10-15% mass concentration of a methyl methacrylate monomer and N,N-dimethylaminoethyl monomer solution, the molar ratio of the methyl methacrylate monomer to the N,N-dimethylaminoethyl monomer is 1:0.9-1.1, then 0.01-0.03 parts of a persulfate salt is added, in-situ polymerization is performed at 70-80 DEG C for 4-5 h to form a grafting layer, washing and drying are performed to obtain the printing and dyeing wastewater high-efficiency decolorizing agent.

[0013] Suitable polymerization conditions can ensure that the grafting layer uniformly covers the surface of the matrix, while avoiding the reduction of active sites caused by excessive crosslinking.

[0014] As can be seen from the above, the printing and dyeing wastewater high-efficiency decolorizing agent described in the present application comprises a multi-layer coating structure:

[0015] The core layer is a zinc-cobalt bimetal modified zeolite matrix: the molar ratio of Zn to Co is 1:2-4, preferably the pore size is 0.5-2 nm, and the specific surface area is ≥300 m 2 / g;

[0016] The intermediate layer is carbon-coated titanium dioxide nanoparticles: supported on the zeolite matrix, the ideal particle size is 10-50 nm, and the carbon layer thickness is 2-5 nm; this structure design not only improves the adsorption capacity of the decolorizing agent for dye molecules, but also enhances its stability in complex water quality.

[0017] The outermost layer is a pH-responsive polymer layer: surface grafting of polymethyl methacrylate monomer and N,N-dimethylaminoethyl copolymer, preferably the molecular weight is 80000-150000 Da, the thickness is 30-100 nm, and by adjusting the thickness and molecular weight of the polymer, the response speed and decolorization effect under different pH conditions can be optimized; the polymer layer shrinks at pH≤5 and swells to release active sites at pH>7; the carbon-coated titanium dioxide nanoparticles supported on the matrix are used to enhance the photocatalytic performance and realize the recovery of the external magnetic field.

[0018] In summary, the decolorizing agent of the present application realizes efficient decolorization through the following components: zinc-cobalt bimetal zeolite matrix, selective adsorption of dye molecules in zeolite pores (pore size matching dye size); cobalt ions (Co 2+ ) catalyze the generation of hydroxyl radicals (·OH), pre-oxidize dye chromophore groups, improve dye capture efficiency, and create favorable conditions for deep degradation; carbon-coated titanium dioxide generates strong oxidizing holes and free radicals under ultraviolet light excitation; the carbon layer promotes electron conduction, inhibits electron-hole recombination, significantly improves the quantum efficiency, and ensures complete mineralization of dye molecules; the pH-responsive polymer layer swells to expose active sites in alkaline environments (pH>7), strengthening adsorption and catalysis; shrinks to protect active components in acidic environments (pH≤5), avoiding deactivation, and can adapt to the pH fluctuations of printing and dyeing wastewater (common pH 9-12), prolonging the service life of the decolorizing agent.

[0019] Preferably, the conditions for acid activation are: using 0.5 mol / L HCl solution at 60°C for 2 h. This pretreatment process can effectively remove impurities in the zeolite, improve its specific surface area and porosity.

[0020] Preferably, the preparation method of the carbon-coated titanium dioxide nanoparticles is as follows: 3-5 parts of hydroxymethyl cellulose ammonium with a DS value of 0.7 or more is added to 50-60 parts of water, dissolved, then 15-20 parts of nanometer titanium dioxide is added, fully stirred and dispersed for 30-40 min, then 0.8-0.9 parts of boric acid is fully stirred, then spray drying (inlet temperature 180℃, outlet temperature 80℃), calcination under absolute oxygen condition at 410±10℃ for 2-3h, then ultrasonic washing with 5% acetic acid solution for 30min and water washing until neutral, and drying to obtain carbon-coated titanium dioxide nanoparticles.

[0021] The particle size of the above-mentioned carbon-coated titanium dioxide nanoparticles is preferably 10-50nm, and the carbon layer thickness is 25nm. The presence of the carbon layer not only improves the dispersibility of the nanoparticles, but also enhances the photocatalytic activity thereof, and realizes rapid separation and recovery under the action of an external magnetic field.

[0022] The present application also provides a printing and dyeing wastewater decolorization treatment method based on the above-mentioned printing and dyeing wastewater efficient decolorization agent,

[0023] comprising the following steps:

[0024] Step 1: microwave pretreatment: the wastewater is treated in a microwave field of 600-800W for 10-20min (50-70℃);

[0025] Step 2: photocatalytic oxidation: 1-3g / L of the decolorization agent is added, and the reaction is carried out under the synergistic action of ultraviolet light (100-280nm, ≥40mW / cm 2 ) and ozone (20-40mg / L) for 30-50min, then the printing and dyeing wastewater efficient decolorization agent is magnetically recovered, and the clear liquid is discharged;

[0026] Preferably, the operation conditions of the photocatalytic oxidation zone are as follows: the ozone dosage is 20-40mg / L, the ultraviolet light intensity is ≥40mW / cm 2 , and the hydraulic retention time is 30-50min. This synergistic action can significantly improve the degradation efficiency of dye molecules.

[0027] Preferably, the reaction time of the microwave intensified pretreatment zone is 10-20min, and the temperature is controlled at 50-70℃. The introduction of the microwave field can accelerate the demulsification and decomposition of organic matter in the wastewater, providing favorable conditions for subsequent treatment.

[0028] In the printing and dyeing wastewater decolorization treatment process, the present application uses microwave intensified pretreatment to demulsify and decompose the wastewater under the action of a microwave field, destroys the colloid structure of dyes, and creates conditions for deep oxidation. After adding the decolorization agent, under the synergistic action of ultraviolet light and ozone: the ultraviolet light excites titanium dioxide to produce strong oxidizing free radicals; the ozone intensifies the free radical chain reaction, completely destroys the dye chromophore group; the pH responsive layer swells in an alkaline environment, fully releasing active sites.

[0029] In addition, the application also includes a regeneration method of the high-efficiency decoloring agent for printing and dyeing wastewater: the decoloring agent is recovered by using an external magnetic field (intensity ≥ 0.3 T); the decoloring agent is immersed in a cleaning agent with a solute of 3-8% of NaCl and 8-10% of citric acid for oscillation for 20-30 min to remove surface contaminants; then, the decoloring agent is washed to neutral and recovered after drying.

[0030] Compared with the prior art, the application has the following advantages:

[0031] 1. The application significantly improves the adsorption capacity and photocatalytic performance of the decoloring agent through the synergistic effect of the zinc-cobalt bimetallic modified zeolite matrix, the pH-responsive polymer grafting layer and the carbon-coated titanium dioxide nanoparticles, and realizes efficient recovery and recycling. In the scheme, the dye molecules are selectively adsorbed by the zeolite pores (the pore size matches the size of the dye); the photocatalysis of titanium dioxide and the ozone oxidation form a double degradation path, ensuring that the chromophore group is completely broken.

[0032] 2. The treatment method of the application combines microwave-enhanced pretreatment and photocatalytic oxidation technology, greatly improves the decolorization efficiency and COD removal rate, reduces the sludge production, has significant environmental and economic benefits; the recycling of the decoloring agent reduces solid waste emissions; the microwave pretreatment replaces the chemical demulsifier, reducing the risk of secondary pollution; the pH-responsive layer ensures the treatment efficiency of alkaline wastewater; the magnetic separation technology is suitable for continuous operation scenarios. DETAILED DESCRIPTION

[0033] The technical solutions in the embodiments of the application will be clearly and completely described below with reference to the embodiments of the application. Obviously, the described embodiments are only part of the embodiments of the application, rather than all the embodiments of the application. Based on the embodiments in the application, all other embodiments obtained by those skilled in the art without creative labor fall within the scope of protection of the application.

[0034] General embodiment

[0035] Unless otherwise specified, the preparation method of the carbon-coated titanium dioxide nanoparticles in the following examples and comparative examples is as follows: 4 parts of hydroxymethyl cellulose ammonium with a DS value of 0.9 are added to 60 parts of water, dissolved, then 18 parts of nano-titanium dioxide are added, fully stirred and dispersed for 30 min, then 0.85 parts of boric acid are fully stirred, then spray drying is performed under the conditions of an inlet air temperature of 180 ℃ and an outlet air temperature of 80 ℃, calcination is performed under anoxic conditions at 410 ℃ for 2.5 h, then ultrasonic washing is performed with 5% acetic acid solution for 30 min and water washing is performed to neutral, and then drying is performed to obtain carbon-coated titanium dioxide nanoparticles;

[0036] The preparation method of the high-efficiency decoloring agent for printing and dyeing wastewater described in the scheme comprises:

[0037] Step (a): After the magnetic zeolite ZIF-8@Fe3O4 is crushed, it is acid activated in 0.3-0.8 mol / L HCl solution at 50-70℃ for 1.5-2.5 h, washed and dried to obtain activated zeolite;

[0038] Step (b): Prepare a 10-15% suspension of activated zeolite, add 20-30% zinc nitrate and cobalt nitrate by mass of activated zeolite, Zn:Co = 1:2-4, react at 80-90℃ for 6-7h to obtain a zinc-cobalt bimetallic modified zeolite matrix suspension.

[0039] Step (c): Add carbon-coated titanium dioxide nanoparticles (zeolite:titanium dioxide mass ratio 10-15:1) to the zinc-cobalt bimetallic modified zeolite matrix suspension, ultrasonically disperse for 20-30 min, and dry to obtain carbon-coated titanium dioxide nanoparticle-supported zinc-cobalt bimetallic modified zeolite matrix.

[0040] Step (d): By weight, add 1 part of carbon-coated titanium dioxide nanoparticle-supported zinc-cobalt bimetallic modified zeolite matrix to 3-5 parts of a 10-15% (w / w) solution of methacrylic acid monomer and N,N-dimethylaminoethyl ester monomer, with a molar ratio of methacrylic acid monomer to N,N-dimethylaminoethyl ester monomer of 1:0.9-1.1. Then add 0.01-0.03 parts of persulfate, and polymerize in situ at 70-80℃ for 4-5 hours to form a graft layer. Wash and dry to obtain a high-efficiency decolorizing agent for dyeing and printing wastewater.

[0041] The process flow of the decolorization treatment method for dyeing and printing wastewater in this plan includes:

[0042] Step 1: Microwave pretreatment: Treat the wastewater in a 600-800W microwave field for 10-20 minutes (50-70℃);

[0043] Step 2: Photocatalytic oxidation: Add 1-3 g / L of decolorizing agent and oxidize under ultraviolet light (254 nm, ≥40 mW / cm²). 2 The reaction proceeds for 30-50 minutes under the synergistic effect of ) and ozone (20-40 mg / L);

[0044] Step 3: Magnetic recovery and regeneration: Add a magnetic field of ≥0.3T to the treated wastewater to recover the high-efficiency decolorizing agent for dyeing and printing wastewater, and regenerate by shaking for 20-30 minutes with a 0.2-0.3mol / L (5% NaCl + 0.1M citric acid mixed solution). After washing and drying, the wastewater is recovered and regenerated.

[0045] The method for recovering and regenerating the high-efficiency decolorizing agent for dyeing and printing wastewater in this scheme is as follows: the decolorizing agent is recovered using an external magnetic field (intensity of 0.5T); it is then immersed in a cleaning agent containing 5% NaCl and 10% citric acid by mass and shaken for 20 minutes to remove surface contaminants; subsequently, it is washed with water until neutral to obtain the regenerated high-efficiency decolorizing agent for dyeing and printing wastewater.

[0046] Example 1

[0047] A method for preparing a highly efficient decolorizing agent for dyeing and printing wastewater includes:

[0048] Step (a): Magnetic zeolite ZIF-8@Fe3O4 was acid-activated in 0.4 mol / L HCl solution at 60℃ for 2.0 h, washed and dried to obtain activated zeolite;

[0049] Step (b): Prepare a 12% (mass fraction) suspension of activated zeolite, add 25% (by mass) of zinc nitrate and cobalt nitrate (Zn:Co molar ratio = 1:2.5) of activated zeolite, and react at 85℃ for 6.5 h to obtain a zinc-cobalt bimetallic modified zeolite matrix suspension.

[0050] Step (c): Add carbon-coated titanium dioxide nanoparticles (zeolite:titanium dioxide mass ratio = 12:1) to the zinc-cobalt bimetallic modified zeolite matrix suspension, ultrasonically disperse for 25 min, and dry to obtain carbon-coated titanium dioxide nanoparticle-supported zinc-cobalt bimetallic modified zeolite matrix.

[0051] Step (d): Add 1 part of carbon-coated titanium dioxide nanoparticle-supported zinc-cobalt bimetallic modified zeolite matrix to 4 parts of a 12.5% ​​(w / w) solution of methacrylic acid monomer and N,N-dimethylaminoethyl ester monomer (molar ratio of methacrylic acid monomer to N,N-dimethylaminoethyl ester monomer = 1:1), then add 0.02 parts of potassium persulfate, and polymerize in situ at 75°C for 4.5 h to form a graft layer. Wash and dry to obtain a high-efficiency decolorizing agent for dyeing and printing wastewater.

[0052] Example 2

[0053] A method for preparing a highly efficient decolorizing agent for dyeing and printing wastewater includes:

[0054] Step (a): Magnetic zeolite ZIF-8@Fe3O4 was acid-activated in 0.5 mol / L HCl solution at 55℃ for 2.0 h, washed and dried to obtain activated zeolite;

[0055] Step (b): Prepare a 10% (mass fraction) suspension of activated zeolite, add 28% (by mass) of zinc nitrate and cobalt nitrate (Zn:Co molar ratio = 1:3) of activated zeolite, and react at 82℃ for 7.0 h to obtain a zinc-cobalt bimetallic modified zeolite matrix suspension.

[0056] Step (c): Add carbon-coated titanium dioxide nanoparticles (zeolite:titanium dioxide mass ratio = 11:1) to the zinc-cobalt bimetallic modified zeolite matrix suspension, ultrasonically disperse for 30 min, and dry to obtain carbon-coated titanium dioxide nanoparticle-supported zinc-cobalt bimetallic modified zeolite matrix.

[0057] Step (d): Add 1 part of carbon-coated titanium dioxide nanoparticle-supported zinc-cobalt bimetallic modified zeolite matrix to 3 parts of a 15% (w / w) solution of methacrylic acid monomer and N,N-dimethylaminoethyl ester monomer (molar ratio of methacrylic acid monomer to N,N-dimethylaminoethyl ester monomer = 1:0.95), then add 0.015 parts of ammonium persulfate, and polymerize in situ at 78℃ for 4.0 h to form a graft layer. Wash and dry to obtain a high-efficiency decolorizing agent for dyeing and printing wastewater.

[0058] Example 3

[0059] A method for preparing a highly efficient decolorizing agent for dyeing and printing wastewater includes:

[0060] Step (a): Magnetic zeolite ZIF-8@Fe3O4 was acid-activated in 0.6 mol / L HCl solution at 65℃ for 1.8 h, washed and dried to obtain activated zeolite;

[0061] Step (b): Prepare a 14% (mass fraction) suspension of activated zeolite, add 22% (mass fraction) of zinc nitrate and cobalt nitrate (Zn:Co molar ratio = 1:3.5) of activated zeolite, and react at 88℃ for 6.0 h to obtain a zinc-cobalt bimetallic modified zeolite matrix suspension;

[0062] Step (c): Add carbon-coated titanium dioxide nanoparticles (zeolite:titanium dioxide mass ratio = 13:1) to the zinc-cobalt bimetallic modified zeolite matrix suspension, ultrasonically disperse for 20 min, and dry to obtain carbon-coated titanium dioxide nanoparticle-supported zinc-cobalt bimetallic modified zeolite matrix.

[0063] Step (d): Add 1 part of carbon-coated titanium dioxide nanoparticle-supported zinc-cobalt bimetallic modified zeolite matrix to 5 parts of a 10% (w / w) solution of methacrylic acid monomer and N,N-dimethylaminoethyl ester monomer (molar ratio of methacrylic acid monomer to N,N-dimethylaminoethyl ester monomer = 1:1.05), then add 0.025 parts of sodium persulfate, and polymerize in situ at 72℃ for 5.0 h to form a graft layer. Wash and dry to obtain a high-efficiency decolorizing agent for dyeing and printing wastewater.

[0064] Example 4

[0065] A method for preparing a highly efficient decolorizing agent for dyeing and printing wastewater includes:

[0066] Step (a): Magnetic zeolite ZIF-8@Fe3O4 was acid-activated in 0.3 mol / L HCl solution at 70 °C for 2.5 h, then washed and dried to obtain activated zeolite;

[0067] Step (b): Prepare a 15% (mass fraction) suspension of activated zeolite, add 30% (by mass) of zinc nitrate and cobalt nitrate (Zn:Co molar ratio = 1:4) of activated zeolite, and react at 80℃ for 7.0 h to obtain a zinc-cobalt bimetallic modified zeolite matrix suspension.

[0068] Step (c): Add carbon-coated titanium dioxide nanoparticles (zeolite:titanium dioxide mass ratio = 15:1) to the zinc-cobalt bimetallic modified zeolite matrix suspension, ultrasonically disperse for 30 min, and dry to obtain carbon-coated titanium dioxide nanoparticle-supported zinc-cobalt bimetallic modified zeolite matrix.

[0069] Step (d): Add 1 part of carbon-coated titanium dioxide nanoparticles loaded with zinc-cobalt bimetallic modified zeolite matrix to 3.5 parts of a 14% (w / w) solution of methacrylic acid monomer and N,N-dimethylaminoethyl ester monomer (molar ratio of methacrylic acid monomer to N,N-dimethylaminoethyl ester monomer = 1:0.9), then add 0.03 parts of potassium persulfate, and polymerize in situ at 80℃ for 4.2 h to form a graft layer. Wash and dry to obtain a high-efficiency decolorizing agent for dyeing and printing wastewater.

[0070] Example 5

[0071] The high-efficiency decolorizing agent for dyeing and printing wastewater prepared in Example 1 was regenerated by magnetic recovery: a 0.5T magnetic field was added to the treated wastewater to recover the high-efficiency decolorizing agent for dyeing and printing wastewater, and the wastewater was regenerated by shaking with a 0.25mol / L (5% NaCl + 0.1M citric acid mixed solution) for 20-30 minutes. After washing and drying, the wastewater was recovered and regenerated to obtain the regenerated high-efficiency decolorizing agent for dyeing and printing wastewater.

[0072] Comparative Example 1

[0073] Compared to Example 1, this is only a Co single-metal modified zeolite matrix.

[0074] Comparative Example 2

[0075] Compared to Example 1, this is only a Zn single-metal modified zeolite matrix.

[0076] Comparative Example 3

[0077] Compared to Example 1, there is no pH-responsive polymer layer.

[0078] Comparative Example 4

[0079] Compared to Example 1, ordinary titanium dioxide was selected.

[0080] Comparative Example 5

[0081] Compared to Example 1, the Zn:Co molar ratio is 1:5.

[0082] Comparative Example 6

[0083] Compared to Example 1, the Zn:Co molar ratio is 1:1.

[0084] Comparative Example 7

[0085] Compared to Example 1, the grafted layer was formed by in-situ polymerization at 75°C for 6 hours.

[0086] Comparative Example 8

[0087] Compared with Example 1, in the preparation method of carbon-coated titanium dioxide nanoparticles, the DS value of ammonium hydroxymethyl cellulose is 0.6.

[0088] Application Example 1

[0089] The desizing wastewater from a factory in Zhejiang Province (COD = 1350 mg / L, color 850 times, pH = 11.2) was selected.

[0090] The process flow of the decolorization treatment method for Examples 1-5 and Comparative Examples 1-6 above, with the addition of commercially available polyferric sulfate polysilicate (PSFS), includes:

[0091] Step 1: Microwave pretreatment: Wastewater is treated in a microwave field of 70℃ and 600W for 20 minutes;

[0092] Step 2: Photocatalytic oxidation: Add 3.0 g / L of decolorizing agent and apply it under 254 nm ultraviolet light (light intensity 40 mW / cm²). 2 The decolorizing agent was reacted for 30 minutes with 20 mg / L ozone and an external 0.5T magnetic field to recover the decolorizing agent, and a decolorized clear liquid was obtained.

[0093] Application Example 2

[0094] The selected mordant dye wastewater contains Cr 3+ 50m g / L, COD1400mg / L, pH=3.8,

[0095] The process flow for the above Examples 1-5 and Comparative Examples 1-6, with the addition of commercially available polyferric silicate sulfate (PSFS), includes:

[0096] Step 1: Microwave pretreatment: Wastewater is treated in a microwave field of 70℃ and 600W for 20 minutes;

[0097] Step 2: Photocatalytic oxidation: Add 3.0 g / L of decolorizing agent and apply it under 254 nm ultraviolet light (light intensity 40 mW / cm²). 2 The decolorizing agent was reacted for 30 minutes with 20 mg / L ozone and an external 0.5T magnetic field to recover the decolorizing agent, and a decolorized clear liquid was obtained.

[0098] Application Example 3

[0099] Wastewater containing 4 wt% NaCl (200 mg / L) of Reactive Black 5 dye was selected.

[0100] The process flow for the above Examples 1-5 and Comparative Examples 1-6, with the addition of commercially available polyferric silicate sulfate (PSFS), includes:

[0101] Step 1: Microwave pretreatment: Wastewater is treated in a microwave field of 70℃ and 600W for 20 minutes;

[0102] Step 2: Photocatalytic oxidation: Add 3.0 g / L of decolorizing agent and apply it under 254 nm ultraviolet light (light intensity 40 mW / cm²). 2 The decolorizing agent was reacted for 30 minutes with 20 mg / L ozone and an external 0.5T magnetic field to recover the decolorizing agent, and a decolorized clear liquid was obtained.

[0103] Application Example 4

[0104] The difference from Application Example 1 is that the microwave pretreatment process has been eliminated.

[0105] Application Example 5

[0106] The difference from Application Example 1 is that ozone was not used in the photocatalytic oxidation process.

[0107] Performance testing:

[0108] Decolorization rate: The decolorization rate was determined by spectrophotometry. Water samples before and after treatment were filtered through a 0.45 μm filter membrane. The absorbance (A0, A1) was measured using a UV-Vis spectrophotometer (such as PerkinElmer Lambda 950) at the maximum absorption wavelength of the dye (such as 598 nm for Reactive Black 5). The decolorization rate (%) was calculated using the formula (1-A1 / A0)×100%. The average value was taken from three parallel measurements.

[0109] COD removal rate: Take 50 mL of water sample, add potassium dichromate solution and silver sulfate catalyst, digest in a COD digester (150℃×2h), cool and titrate with ferrous ammonium sulfate, and perform a blank control at the same time. Calculate according to the formula COD removal rate (%) = (1-COD1 / COD0)×100%, where COD0 and COD1 are the chemical oxygen demand (mg / L) before and after treatment, respectively.

[0110] Heavy metal removal rate: Water samples were filtered through a 0.22 μm filter membrane, acidified with 2% nitric acid, and then injected. For chromium-containing samples, the valence state needed to be distinguished: hexavalent chromium was removed using the diphenylcarbazide spectrophotometric method, and trivalent chromium was calculated by subtracting hexavalent chromium from total chromium. The heavy metal removal rate (%) was calculated using the formula: Heavy metal removal rate (%) = (1 - C1 / C0) × 100%, where C0 and C1 are the heavy metal concentrations (mg / L) before and after treatment.

[0111] The test results are shown in Table 1.

[0112]

[0113]

[0114]

[0115]

[0116] The embodiments of this invention achieve technological breakthroughs through a multi-level synergistic mechanism: In the zinc-cobalt bimetallic modified zeolite matrix, zinc ions are dedicated to dye molecule adsorption, while cobalt ions catalyze the activation of peroxides, and the two synergistically form an adsorption-oxidation closed loop (compared to single-metal comparative examples 1 and 2, which suffer from efficiency collapse due to functional loss); carbon-coated titanium dioxide constructs a high-speed electron channel, significantly inhibiting photogenerated carrier recombination (compared to the uncoated comparative example 4, which suffers from severe charge annihilation); the pH-responsive polymer layer swells in alkaline wastewater (application example 1) to expose the active interface, and shrinks in acidic chromium-containing wastewater (application example 2) to form an anti-corrosion barrier (compared to the uncoated comparative example 3, which fails in both acidic and alkaline environments due to deactivation of active sites); the molecular sieve effect of the zeolite framework, combined with the hydrophobic groups of the polymer, effectively resists ion interference in high-salt environments (application example 3) (compared to commercially available ordinary carriers that collapse due to salting out). When encountering process defects, the endogenous catalysis of the bimetallic center and the carbon-coated photocatalysis synergistically maintain the basic oxidation capacity (Application Examples 4 and 5), while Comparative Examples 5 and 6, with an imbalanced bimetallic ratio, experience systemic collapse due to pore blockage or catalytic kinetic imbalance. In Comparative Example 7, the polymerization time was extended to 6 hours, increasing the graft layer thickness and hindering the active components, resulting in performance slightly lower than Example 1, but still higher than Comparative Example 3 without a polymer layer. In Comparative Example 8, the carbon coating layer was uneven due to a low DS value, reducing active sites, and its performance was only slightly higher than Comparative Example 4. This system comprehensively covers the shortcomings of traditional technologies in adsorption capacity, oxidation depth, and environmental adaptability through four-dimensional synergy: adsorption site design, catalytic center regulation, charge transport enhancement, and intelligent environmental response.

Claims

1. A highly efficient decolorizing agent for dyeing and printing wastewater, characterized in that, Its preparation method includes the following steps: Step (a): The magnetic zeolite is pulverized and then activated to obtain activated zeolite; Step (b): Prepare a 10-15% suspension of activated zeolite, add 20-30% of zinc salt and cobalt salt by mass of activated zeolite, Zn:Co=1:2-4, react at 80-90℃ for 6-7h to obtain a zinc-cobalt bimetallic modified zeolite matrix suspension. Step (c): Add carbon-coated titanium dioxide nanoparticles to a zinc-cobalt bimetallic modified zeolite matrix suspension, with a zeolite:titanium dioxide mass ratio of 10-15:1, ultrasonically disperse for 20-30 min, and dry to obtain a zinc-cobalt bimetallic modified zeolite matrix supported on carbon-coated titanium dioxide nanoparticles. Step (d): By weight, add 1 part of carbon-coated titanium dioxide nanoparticle-supported zinc-cobalt bimetallic modified zeolite matrix to 3-5 parts of a 10-15% (w / w) solution of methacrylic acid monomer and N,N-dimethylaminoethyl ester monomer, with a molar ratio of methacrylic acid monomer to N,N-dimethylaminoethyl ester monomer of 1:0.9-1.

1. Then add 0.01-0.03 parts of persulfate, and polymerize in situ at 70-80℃ for 4-5 hours to form a graft layer. Wash and dry to obtain a high-efficiency decolorizing agent for dyeing and printing wastewater.

2. The high-efficiency decolorizing agent for dyeing and printing wastewater as described in claim 1, characterized in that, In step (a), the activation process is as follows: after the magnetic zeolite is crushed, it is acid activated in 0.3-0.8 mol / L HCl solution at 50-70℃ for 1.5-2.5 h, then washed and dried.

3. The high-efficiency decolorizing agent for dyeing and printing wastewater as described in claim 1, characterized in that, In step (b), the zinc salt is zinc nitrate and the cobalt salt is cobalt nitrate.

4. The high-efficiency decolorizing agent for dyeing and printing wastewater as described in claim 1, characterized in that, In step (c), the preparation method of the carbon-coated titanium dioxide nanoparticles is as follows: by weight, 3-5 parts of ammonium hydroxymethyl cellulose are added to 50-60 parts of water, dissolved, and then 15-20 parts of nano-titanium dioxide are added, stirred and dispersed, and then 0.8-0.9 parts of boric acid are added and stirred thoroughly. Then, the mixture is spray-dried, calcined in an oxygen-free environment, washed, and dried to obtain carbon-coated titanium dioxide nanoparticles.

5. The high-efficiency decolorizing agent for dyeing and printing wastewater as described in claim 4, characterized in that, The DS value of the ammonium hydroxymethylcellulose is ≥0.

7.

6. The high-efficiency decolorizing agent for dyeing and printing wastewater as described in claim 4, characterized in that, The conditions for spray drying are: inlet air temperature 180℃ and outlet air temperature 80℃.

7. The high-efficiency decolorizing agent for dyeing and printing wastewater as described in claim 4, characterized in that, The oxygen-free calcination process is as follows: calcination is carried out at 410±10℃ under oxygen-free conditions for 2-3 hours.

8. The application of a high-efficiency decolorizing agent for dyeing and printing wastewater as described in any one of claims 1-7, characterized in that, include: Step 1: Microwave pretreatment: Treat wastewater in a microwave field of 50-70℃ and 600-800W for 10-20 minutes; Step 2: Photocatalytic oxidation: Add 1-3 g / L of decolorizing agent and react for 30-50 min under the synergistic effect of ultraviolet light and ozone. After magnetic recovery of the high-efficiency decolorizing agent from the dyeing and printing wastewater, discharge the clear liquid.

9. The application of the high-efficiency decolorizing agent for dyeing and printing wastewater as described in claim 8, characterized in that, The process of magnetically recovering the high-efficiency decolorizing agent for dyeing and printing wastewater is as follows: a magnetic field of ≥0.3T is added to the treated wastewater to recover the high-efficiency decolorizing agent for dyeing and printing wastewater, followed by adding it to a cleaning agent for shaking and regeneration, washing and drying, and then recovering and regenerating; the solute in the cleaning agent is 3-8% NaCl and 8-10% citric acid by mass fraction.

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