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

Abstract

The invention belongs to the technical field of water treatment, and particularly relates to an efficient decolorizing agent for printing and dyeing wastewater and a decolorizing treatment method.The preparation method comprises the following steps that (a) magnetic zeolite is smashed and then activated, and activated zeolite is obtained; (b) modifying the activated zeolite to prepare a zinc-cobalt bimetallic modified zeolite matrix suspension; (c) adding the carbon-coated titanium dioxide nano-particles into the zinc-cobalt bimetallic modified zeolite matrix suspension to obtain a carbon-coated titanium dioxide nano-particle loaded zinc-cobalt bimetallic modified zeolite matrix; and (d) carrying out surface in-situ polymerization on a grafting layer to obtain the efficient decolorizing agent for printing and dyeing wastewater. According to the scheme, through the synergistic effect of the zinc-cobalt double-metal modified zeolite matrix, the pH response type polymer grafting layer and the carbon-coated titanium dioxide nanoparticles and in combination with microwave enhanced pretreatment and photocatalytic oxidation technologies, the adsorption capacity and photocatalytic performance of the decolorizing agent are remarkably improved, and efficient recycling and cyclic utilization are achieved.

Description

Technical Field

[0001] The invention belongs to the technical field of water treatment, and in particular relates to a high-efficiency decolorizing agent and a decolorizing treatment method for printing and dyeing wastewater. Background Art

[0002] Printing and dyeing wastewater has become a major challenge in industrial wastewater treatment due to its complex composition, high chroma, high concentration of organic pollutants, and significant biological toxicity. Chromophores such as azo bonds and anthraquinone structures in dye molecules are chemically stable, making traditional treatment methods such as coagulation and sedimentation, adsorption, and biodegradation difficult to achieve efficient decolorization and organic matter removal. Furthermore, existing treatment technologies are often accompanied by high sludge production, low resource utilization, and secondary pollution, further limiting their effectiveness.

[0003] Currently, most commonly used decolorizers are single-function inorganic or organic materials, such as iron salts, aluminum salts, and modified activated carbon. However, these materials suffer from limited decolorization efficiency, poor adaptability, and difficulty in recycling. In particular, for high-concentration, recalcitrant printing and dyeing wastewater, a single decolorizer often fails to meet practical needs. Furthermore, existing treatment processes lack effective resource utilization methods for sludge, leading to sludge accumulation and increased disposal costs, further exacerbating the environmental burden.

[0004] On the other hand, advanced oxidation technology, a research hotspot in recent years, can destroy the dye's molecular structure through strong oxidants (such as ozone and hydrogen peroxide). However, its high operating costs and strict requirements for reaction conditions (such as pH and catalyst performance) make it difficult to achieve large-scale promotion. In addition, existing photoelectrocatalytic technology still faces many challenges in electrode material selection, light energy utilization, and system integration, limiting its application in practical engineering.

[0005] In view of the above problems, it is particularly important to develop a new type of decolorizing agent and its supporting treatment process that has high efficiency decolorizing ability, recyclable characteristics and sludge resource utilization potential. 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 operating costs and reduce secondary pollution; third, it can work synergistically with other treatment units to achieve deep purification and resource utilization of wastewater. The present invention aims to solve the problems of low decolorization efficiency, difficult sludge treatment and high operating costs in the existing technology, and provide a new solution for the efficient treatment of printing and dyeing wastewater.

[0006] In summary, decolorization of printing and dyeing wastewater, which contains a large amount of recalcitrant organic dyes and auxiliaries, has always been a challenge in the environmental protection field. While traditional decolorization methods such as coagulation and adsorption are simple to operate, they suffer from low decolorization efficiency, high sludge production, and secondary pollution. Therefore, the development of efficient, recyclable, and environmentally friendly decolorizers and supporting treatment methods is of great significance. Summary of the Invention

[0007] The present invention relates to the technical field of wastewater treatment, and in particular to a high-efficiency decolorant for printing and dyeing wastewater and a decolorization treatment method thereof. Through the synergistic effect of a zinc-cobalt bimetallic modified zeolite matrix, a pH-responsive polymer graft layer, and carbon-coated titanium dioxide nanoparticles, combined with microwave-enhanced pretreatment and photocatalytic oxidation technology, the adsorption capacity and photocatalytic performance of the decolorant are significantly improved, and efficient recovery and recycling are achieved.

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

[0009] Step (a): The magnetic zeolite is crushed and activated with 0.3-0.8 mol / L HCl solution at 50-70° C. for 1.5-2.5 h, followed by washing and drying to obtain activated zeolite;

[0010] Step (b): preparing a 10-15% suspension of activated zeolite, adding zinc nitrate and cobalt nitrate in an amount of 20-30% by weight of the activated zeolite, with Zn:Co = 1:2-4, and reacting at 80-90° C. for 6-7 hours to obtain a zinc-cobalt bimetallic modified zeolite matrix suspension;

[0011] Step (c): adding carbon-coated titanium dioxide nanoparticles (zeolite: titanium dioxide mass ratio of 10-15:1) to the zinc-cobalt bimetallic modified zeolite matrix suspension, ultrasonically dispersing for 20-30 minutes, and drying to obtain a carbon-coated titanium dioxide nanoparticle-loaded zinc-cobalt bimetallic modified zeolite matrix;

[0012] Step (d): adding 1 part by weight of a carbon-coated titanium dioxide nanoparticle-loaded zinc-cobalt bimetallic modified zeolite matrix to 3-5 parts by weight of a 10-15% mass concentration of methacrylic acid monomer and N,N-dimethylaminoethyl ester monomer solution, wherein the molar ratio of the methacrylic acid monomer to the N,N-dimethylaminoethyl ester monomer is 1:0.9-1.1, and then adding 0.01-0.03 parts of persulfate, in situ polymerization is carried out at 70-80° C. for 4-5 hours to form a graft layer, and the mixture is washed and dried to obtain a high-efficiency decolorizer for printing and dyeing wastewater.

[0013] Appropriate polymerization conditions can ensure that the grafted layer is evenly covered on the substrate surface while avoiding the reduction of active sites caused by excessive cross-linking.

[0014] From the above, it can be seen that the high-efficiency decolorant for printing and dyeing wastewater described in this scheme includes a multi-layer coating structure:

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

[0016] The middle layer is carbon-coated titanium dioxide nanoparticles: loaded on a zeolite matrix, with an ideal particle size of 10-50nm and a carbon layer thickness of 2-5nm; this structural design not only improves the decolorizer's adsorption capacity for dye molecules, but also enhances its stability in complex water quality.

[0017] The outermost layer is a pH-responsive polymer layer: the surface is grafted with a copolymer of polymethacrylic acid monomer and N,N-dimethylaminoethyl ester, preferably with a molecular weight of 80,000-150,000 Da and a thickness of 30-100 nm. By adjusting the thickness and molecular weight of the polymer, its response speed and decolorization effect under different pH conditions can be optimized; the polymer layer shrinks when the pH is ≤ 5 and swells to release active sites when the pH is > 7; carbon-coated titanium dioxide nanoparticles loaded on the substrate are used to enhance photocatalytic performance and achieve recovery in an external magnetic field.

[0018] In summary, the decolorizing agent of the present invention achieves efficient decolorization through the synergistic effect of the following components: zinc-cobalt bimetallic zeolite matrix, zeolite pores selectively adsorb dye molecules (pore size matches dye size); cobalt ions (Co 2+ ) catalyzes the generation of hydroxyl radicals (·OH), pre-oxidizes the dye chromophores, improves the dye capture efficiency, and creates favorable conditions for deep degradation; carbon-coated titanium dioxide produces strong oxidizing holes and free radicals under ultraviolet light excitation; the carbon layer promotes electron conduction, inhibits electron-hole recombination, significantly improves the photoquantum efficiency, and ensures the thorough mineralization of the dye molecules; the pH-responsive polymer layer swells in an alkaline environment (pH>7) to expose active sites, enhance adsorption and catalysis; in an acidic environment (pH≤5), it shrinks to protect the active components and avoid inactivation. It can adapt to pH fluctuations of printing and dyeing wastewater (commonly pH9-12) and extend the service life of the decolorizer.

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

[0020] Preferably, the preparation method of the carbon-coated titanium dioxide nanoparticles is as follows: by weight, 3-5 parts of hydroxymethyl cellulose ammonium with a DS value ≥ 0.7 are added to 50-60 parts of water, and after dissolution, 15-20 parts of nano-titanium dioxide are added, and the mixture is fully stirred and dispersed for 30-40 minutes, followed by adding 0.8-0.9 parts of boric acid and fully stirring, followed by spray drying (inlet air temperature 180°C, outlet air temperature 80°C), calcining at 410±10°C under anaerobic conditions for 2-3 hours, and then ultrasonically washing with 5% acetic acid solution for 30 minutes and washing with water until neutral, and drying to obtain carbon-coated titanium dioxide nanoparticles.

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

[0022] The present invention also proposes a decolorization treatment method for printing and dyeing wastewater based on the above-mentioned high-efficiency decolorizer for printing and dyeing wastewater.

[0023] The following steps are involved:

[0024] Step 1: Microwave pretreatment: The wastewater is treated in a 600-800W microwave field for 10-20min (50-70°C);

[0025] Step 2: Photocatalytic oxidation: Add 1-3g / L of decolorizer and irradiate under ultraviolet light (100-280nm, ≥40mW / cm 2 ) and ozone (20-40 mg / L) for 30-50 min, magnetically recover the high-efficiency decolorant for printing and dyeing wastewater and then discharge the clear liquid;

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

[0027] Preferably, the reaction time of the microwave-enhanced pretreatment zone is 10-20 minutes, and the temperature is controlled at 50-70° C. 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] During the decolorization process of printing and dyeing wastewater, this solution utilizes microwave-enhanced pretreatment to demulsify the wastewater under the action of the microwave field, destroying the dye's colloidal structure and creating conditions for deep oxidation. After the addition of the decolorizer, the synergistic action of ultraviolet light and ozone: UV light excites titanium dioxide to produce strong oxidizing free radicals; ozone intensifies the free radical chain reaction, completely destroying the dye's chromophores; and the pH-responsive layer swells in an alkaline environment, fully releasing active sites.

[0029] In addition, the present invention also includes a method for regenerating a high-efficiency decolorant for printing and dyeing wastewater: using an external magnetic field (intensity ≥ 0.3T) to recover the decolorant; immersing the decolorant in a cleaning agent containing 3-8% by mass of NaCl and 8-10% by mass of citric acid and shaking it for 20-30 minutes to remove surface pollutants; then washing with water until neutral, washing and drying, and then recovering and regenerating.

[0030] Compared with the prior art, the advantages of the present invention are:

[0031] 1. This invention significantly enhances the adsorption capacity and photocatalytic performance of the decolorizer through the synergistic effects of a zinc-cobalt bimetallic modified zeolite matrix, a pH-responsive polymer graft layer, and carbon-coated titanium dioxide nanoparticles, enabling efficient recovery and recycling. In this scheme, dye molecules are selectively adsorbed by the zeolite pores (pore size matched to the dye size); titanium dioxide photocatalysis and ozone oxidation form a dual degradation pathway, ensuring the complete breakdown of chromophores.

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

[0033] The following will be combined with the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the embodiments described are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making creative efforts are within the scope of protection of the present invention.

[0034] Overall 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 by weight of hydroxymethylcellulose ammonium with a DS value of 0.9 are added to 60 parts of water, and after dissolution, 18 parts of nano-titanium dioxide are added, and the mixture is fully stirred and dispersed for 30 minutes, followed by adding 0.85 parts of boric acid and fully stirring, followed by spray drying at an inlet air temperature of 180°C and an outlet air temperature of 80°C, and after drying, calcining at 410°C under anaerobic conditions for 2.5 hours, and then ultrasonically washing with a 5% acetic acid solution for 30 minutes and washing with water until neutral, and drying to obtain carbon-coated titanium dioxide nanoparticles;

[0036] The method for preparing a high-efficiency decolorant for printing and dyeing wastewater described in this scheme comprises:

[0037] Step (a): Magnetic zeolite ZIF-8@Fe3O4 is crushed and activated with 0.3-0.8 mol / L HCl solution at 50-70°C for 1.5-2.5 h, followed by washing and drying to obtain activated zeolite;

[0038] Step (b): preparing a 10-15% suspension of activated zeolite, adding zinc nitrate and cobalt nitrate in an amount of 20-30% by weight of the activated zeolite, with Zn:Co = 1:2-4, and reacting at 80-90° C. for 6-7 hours to obtain a zinc-cobalt bimetallic modified zeolite matrix suspension;

[0039] Step (c): adding carbon-coated titanium dioxide nanoparticles (zeolite: titanium dioxide mass ratio of 10-15:1) to the zinc-cobalt bimetallic modified zeolite matrix suspension, ultrasonically dispersing for 20-30 minutes, and drying to obtain a carbon-coated titanium dioxide nanoparticle-loaded zinc-cobalt bimetallic modified zeolite matrix;

[0040] Step (d): adding 1 part by weight of a carbon-coated titanium dioxide nanoparticle-loaded zinc-cobalt bimetallic modified zeolite matrix to 3-5 parts by weight of a 10-15% mass concentration of methacrylic acid monomer and N,N-dimethylaminoethyl ester monomer solution, wherein the molar ratio of the methacrylic acid monomer to the N,N-dimethylaminoethyl ester monomer is 1:0.9-1.1, and then adding 0.01-0.03 parts of persulfate, performing in-situ polymerization at 70-80° C. for 4-5 hours to form a graft layer, washing, and drying to obtain a high-efficiency decolorizer for printing and dyeing wastewater;

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

[0042] Step 1: Microwave pretreatment: The wastewater is treated in a 600-800W microwave field for 10-20min (50-70°C);

[0043] Step 2: Photocatalytic oxidation: Add 1-3g / L of decolorizer and oxidize under ultraviolet light (254nm, ≥40mW / cm 2 ) and ozone (20-40 mg / L) for 30-50 min;

[0044] Step 3: Magnetic recovery and regeneration: Add a ≥0.3T magnetic field to the treated wastewater to recover the high-efficiency decolorant for printing and dyeing wastewater, 0.2-0.3mol / L (5% NaCl + 0.1M citric acid mixed solution) and shake for 20-30min, then wash and dry before recovery and regeneration;

[0045] The recovery and regeneration method of the high-efficiency decolorant for printing and dyeing wastewater of this scheme includes: using an external magnetic field (with an intensity of 0.5T) to recover the decolorant; immersing it in a cleaning agent with a solute of 5% by mass of NaCl and 10% by mass of citric acid and shaking it for 20 minutes to remove surface pollutants; then washing it with water until it is neutral to obtain a regenerated high-efficiency decolorant for printing and dyeing wastewater.

[0046] Example 1

[0047] A method for preparing a high-efficiency decolorant for printing and dyeing wastewater, comprising:

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

[0049] Step (b): Activated zeolite was prepared into a 12% (mass fraction) suspension, and zinc nitrate and cobalt nitrate (Zn:Co molar ratio = 1:2.5) with a mass fraction of 25% of the activated zeolite were added, and the mixture was reacted at 85°C for 6.5 hours to obtain a zinc-cobalt bimetallic modified zeolite matrix suspension;

[0050] Step (c): adding carbon-coated titanium dioxide nanoparticles (zeolite: titanium dioxide mass ratio = 12:1) to the zinc-cobalt bimetallic modified zeolite matrix suspension, ultrasonically dispersing for 25 minutes, and drying to obtain a carbon-coated titanium dioxide nanoparticle-loaded zinc-cobalt bimetallic modified zeolite matrix;

[0051] Step (d): Add 1 part of carbon-coated titanium dioxide nanoparticles loaded with zinc-cobalt bimetallic modified zeolite matrix to 4 parts of 12.5% ​​mass concentration of methacrylic acid monomer and N,N-dimethylaminoethyl ester monomer solution (methacrylic acid monomer and N,N-dimethylaminoethyl ester monomer molar ratio = 1:1), then add 0.02 parts of potassium persulfate, in situ polymerize at 75°C for 4.5 hours to form a grafted layer, wash, and dry to obtain a high-efficiency decolorizer for printing and dyeing wastewater.

[0052] Example 2

[0053] A method for preparing a high-efficiency decolorant for printing and dyeing wastewater, comprising:

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

[0055] Step (b): Activated zeolite was prepared into a 10% (mass fraction) suspension, and zinc nitrate and cobalt nitrate (Zn:Co molar ratio = 1:3) with a mass fraction of 28% of the activated zeolite were added, and the mixture was reacted at 82°C for 7.0h to obtain a zinc-cobalt bimetallic modified zeolite matrix suspension;

[0056] Step (c): adding carbon-coated titanium dioxide nanoparticles (zeolite: titanium dioxide mass ratio = 11:1) to the zinc-cobalt bimetallic modified zeolite matrix suspension, ultrasonically dispersing for 30 minutes, and drying to obtain a carbon-coated titanium dioxide nanoparticle-loaded zinc-cobalt bimetallic modified zeolite matrix;

[0057] Step (d): Add 1 part of carbon-coated titanium dioxide nanoparticles loaded with zinc-cobalt bimetallic modified zeolite matrix to 3 parts of 15% mass concentration of methacrylic acid monomer and N,N-dimethylaminoethyl ester monomer solution (methacrylic acid monomer and N,N-dimethylaminoethyl ester monomer molar ratio = 1:0.95), then add 0.015 parts of ammonium persulfate, in situ polymerize at 78°C for 4.0h to form a grafted layer, wash, and dry to obtain a high-efficiency decolorizer for printing and dyeing wastewater.

[0058] Example 3

[0059] A method for preparing a high-efficiency decolorant for printing and dyeing wastewater, comprising:

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

[0061] Step (b): Activated zeolite was prepared into a 14% (mass fraction) suspension, and zinc nitrate and cobalt nitrate (Zn:Co molar ratio = 1:3.5) were added at 22% of the mass of the activated zeolite, and the mixture was reacted at 88°C for 6.0 hours to obtain a zinc-cobalt bimetallic modified zeolite matrix suspension;

[0062] Step (c): adding carbon-coated titanium dioxide nanoparticles (zeolite: titanium dioxide mass ratio = 13:1) to the zinc-cobalt bimetallic modified zeolite matrix suspension, ultrasonically dispersing for 20 minutes, and drying to obtain a carbon-coated titanium dioxide nanoparticle-loaded zinc-cobalt bimetallic modified zeolite matrix;

[0063] Step (d): Add 1 part of carbon-coated titanium dioxide nanoparticles loaded with zinc-cobalt bimetallic modified zeolite matrix to 5 parts of 10% mass concentration of methacrylic acid monomer and N,N-dimethylaminoethyl ester monomer solution (methacrylic acid monomer and N,N-dimethylaminoethyl ester monomer molar ratio = 1:1.05), then add 0.025 parts of sodium persulfate, in situ polymerize at 72°C for 5.0h to form a grafted layer, wash, and dry to obtain a high-efficiency decolorizer for printing and dyeing wastewater.

[0064] Example 4

[0065] A method for preparing a high-efficiency decolorant for printing and dyeing wastewater, comprising:

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

[0067] Step (b): Activated zeolite was prepared into a 15% (mass fraction) suspension, and zinc nitrate and cobalt nitrate (Zn:Co molar ratio = 1:4) with a mass fraction of 30% of the activated zeolite were added, and the mixture was reacted at 80°C for 7.0h to obtain a zinc-cobalt bimetallic modified zeolite matrix suspension;

[0068] Step (c): adding carbon-coated titanium dioxide nanoparticles (zeolite: titanium dioxide mass ratio = 15:1) to the zinc-cobalt bimetallic modified zeolite matrix suspension, ultrasonically dispersing for 30 minutes, and drying to obtain a carbon-coated titanium dioxide nanoparticle-loaded 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 14% mass concentration of methacrylic acid monomer and N,N-dimethylaminoethyl ester monomer solution (methacrylic acid monomer and N,N-dimethylaminoethyl ester monomer molar ratio = 1:0.9), then add 0.03 parts of potassium persulfate, in situ polymerize at 80°C for 4.2h to form a grafted layer, wash, and dry to obtain an efficient decolorizer for printing and dyeing wastewater.

[0070] Example 5

[0071] The high-efficiency decolorant for printing and dyeing 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 decolorant for printing and dyeing wastewater, and 0.25mol / L (5% NaCl+0.1M citric acid mixed solution) was shaken and regenerated for 20-30min. After washing and drying, the high-efficiency decolorant for printing and dyeing wastewater was recovered and regenerated to obtain a regenerated high-efficiency decolorant for printing and dyeing wastewater.

[0072] Comparative Example 1

[0073] Compared with Example 1, only the Co single metal modified the zeolite matrix.

[0074] Comparative Example 2

[0075] Compared with Example 1, only the Zn single metal modified zeolite matrix.

[0076] Comparative Example 3

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

[0078] Comparative Example 4

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

[0080] Comparative Example 5

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

[0082] Comparative Example 6

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

[0084] Comparative Example 7

[0085] Compared with Example 1, the graft layer was formed by in-situ polymerization at 75° C. for 6 h.

[0086] Comparative Example 8

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

[0088] Application Example 1

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

[0090] The process flow of the decolorization treatment method of the above Examples 1-5 and Comparative Examples 1-6, in which commercially available polyferric silicate sulfate (PSFS) is added, includes:

[0091] Step 1: Microwave pretreatment: wastewater was treated in a microwave field at 70°C and 600W for 20 min;

[0092] Step 2: Photocatalytic oxidation: Add 3.0g / L of decolorizer and irradiate under 254nm ultraviolet light (intensity 40mW / cm 2 ) and 20 mg / L ozone for 30 min, and then a 0.5 T magnetic field was added to recover the decolorizing agent to obtain a decolorized clear solution.

[0093] Application Example 2

[0094] Mordant dye wastewater containing Cr 3+ 50m g / L, COD1400mg / L, pH=3.8,

[0095] The process flow of 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 was treated in a microwave field at 70°C and 600W for 20 min;

[0097] Step 2: Photocatalytic oxidation: Add 3.0g / L of decolorizer and irradiate under 254nm ultraviolet light (intensity 40mW / cm 2 ) and 20 mg / L ozone for 30 min, and then a 0.5 T magnetic field was added to recover the decolorizing agent to obtain a decolorized clear solution.

[0098] Application Example 3

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

[0100] The process flow of 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 was treated in a microwave field at 70°C and 600W for 20 min;

[0102] Step 2: Photocatalytic oxidation: Add 3.0g / L of decolorizer and irradiate under 254nm ultraviolet light (intensity 40mW / cm 2 ) and 20 mg / L ozone for 30 min, and then a 0.5 T magnetic field was added to recover the decolorizing agent to obtain a decolorized clear solution.

[0103] Application Example 4

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

[0105] Application Example 5

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

[0107] Performance testing:

[0108] Decolorization rate: Detected by spectrophotometry. Take water samples before and after treatment and filter them through a 0.45 μm filter membrane. Use a UV-visible spectrophotometer (such as PerkinElmer Lambda950) to measure the absorbance (A0, A1) at the maximum absorption wavelength of the dye (such as 598 nm for Reactive Black 5). Calculate the decolorization rate (%) according to the formula: (1-A1 / A0)×100%. Repeat the measurement three times and take the average value.

[0109] COD removal rate: Take 50mL of water sample, add potassium dichromate solution and silver sulfate catalyst, digest it in a COD digester (150℃×2h), cool it down, titrate it with ammonium ferrous sulfate, and make 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 membrane, acidified with 2% nitric acid, and then injected. Chromium-containing samples require valence analysis: hexavalent chromium is determined using diphenylcarbazide spectrophotometry, while trivalent chromium is calculated by subtracting hexavalent chromium from total chromium. Heavy Metal Removal Rate (%) = (1-C1 / C0) × 100%, where C0 and C1 represent 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 the present invention achieve a technological breakthrough through a multi-level synergistic mechanism: zinc ions in the zinc-cobalt bimetallic modified zeolite matrix are responsible for the adsorption of dye molecules, and cobalt ions catalyze the activation of peroxides, and the two synergistically form an adsorption-oxidation closed loop (compared with single metal comparative examples 1 and 2, which have efficiency collapse due to functional loss); carbon-coated titanium dioxide constructs an electron high-speed channel, significantly inhibiting the recombination of photogenerated carriers (compared with comparative example 4 without carbon coating, which has serious 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 with comparative example 3 without a polymer layer, which fails in acidic and alkaline environments due to deactivation of active sites); the molecular sieve effect of the zeolite framework combined with the hydrophobic group of the polymer effectively resists ion interference in a high-salt environment (application example 3) (compared with ordinary carrier commercial products 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 the comparative examples 5 and 6 with an imbalance in the bimetallic ratio cause systemic collapse due to pore blockage or catalytic kinetic imbalance. In comparative example 7, the polymerization time is extended to 6h, and the increased thickness of the grafted layer hinders the active components, resulting in performance slightly lower than that of Example 1, but still higher than that of comparative example 3 without a polymer layer. The carbon coating layer of comparative example 8 is uneven due to its low DS value, and the active sites are reduced, and the performance is only slightly higher than that of comparative example 4. This solution system comprehensively covers the defects of traditional technologies in adsorption capacity, oxidation depth and environmental adaptability through the four-dimensional synergy of adsorption site design, catalytic center regulation, charge transfer enhancement and environmental response intelligence.

Claims

1. A high-efficiency decolorizing agent for printing and dyeing wastewater, characterized in that: The preparation method comprises the following steps: Step (a): pulverizing and activating the magnetic zeolite to obtain activated zeolite; Step (b): preparing a 10-15% suspension of activated zeolite, adding 20-30% of the weight of the activated zeolite to a zinc salt and a cobalt salt, with Zn:Co = 1:2-4, and reacting at 80-90° C. for 6-7 hours to obtain a zinc-cobalt bimetallic modified zeolite matrix suspension; Step (c): adding carbon-coated titanium dioxide nanoparticles to the zinc-cobalt bimetallic modified zeolite matrix suspension, with a zeolite:titanium dioxide mass ratio of 10-15:1, ultrasonically dispersing for 20-30 minutes, and drying to obtain a carbon-coated titanium dioxide nanoparticle-loaded zinc-cobalt bimetallic modified zeolite matrix; Step (d): adding 1 part by weight of a carbon-coated titanium dioxide nanoparticle-loaded zinc-cobalt bimetallic modified zeolite matrix to 3-5 parts by weight of a 10-15% mass concentration of methacrylic acid monomer and N,N-dimethylaminoethyl ester monomer solution, wherein the molar ratio of the methacrylic acid monomer to the N,N-dimethylaminoethyl ester monomer is 1:0.9-1.1, and then adding 0.01-0.03 parts of persulfate, in situ polymerization is carried out at 70-80° C. for 4-5 hours to form a graft layer, and the mixture is washed and dried to obtain a high-efficiency decolorizer for printing and dyeing wastewater.

2. The high-efficiency decolorizing agent for printing and dyeing wastewater according to claim 1, wherein In the step (a), the activation process is as follows: the magnetic zeolite is crushed, activated with 0.3-0.8 mol / L HCl solution at 50-70° C. for 1.5-2.5 h, and then washed and dried.

3. The high-efficiency decolorizing agent for printing and dyeing wastewater according to claim 1, wherein In step (b), the zinc salt is zinc nitrate, and the cobalt salt is cobalt nitrate.

4. The high-efficiency decolorizing agent for printing and dyeing wastewater according to claim 1, wherein In step (c), the preparation method of the carbon-coated titanium dioxide nanoparticles is as follows: by weight, 3-5 parts of hydroxymethylcellulose ammonium are added to 50-60 parts of water, and after dissolution, 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, followed by spray drying, anaerobic calcination, washing, and drying to obtain carbon-coated titanium dioxide nanoparticles.

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

7.

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

7. The high-efficiency decolorizing agent for printing and dyeing wastewater according to claim 4, characterized in that The anaerobic calcination process is: calcining at 410±10°C under anaerobic conditions for 2-3 hours.

8. A method for preparing the high-efficiency decolorizing agent for printing and dyeing wastewater according to any one of claims 1 to 7.

9. A method for using the high-efficiency decolorizing agent for printing and dyeing wastewater according to any one of claims 1 to 7, characterized in that: include: Step 1: Microwave pretreatment: The wastewater is treated in a microwave field at 50-70°C and 600-800W for 10-20 minutes; Step 2: Photocatalytic oxidation: Add 1-3g / L of decolorizer, react for 30-50min under the synergy of ultraviolet light and ozone, magnetically recover the high-efficiency decolorizer of printing and dyeing wastewater and discharge the clear liquid.

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

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