A method for treating wastewater based on three-phase catalytic oxidation

Abstract

The application discloses a wastewater treatment method based on three-phase catalytic oxidation, which adopts a catalytic oxidation tower for treatment, wherein an aeration pipe and a catalyst layer are arranged from bottom to top in the catalytic oxidation tower, a water inlet pipe is arranged between the aeration pipe and the catalyst layer, and a water outlet pipe is arranged above the catalyst layer; a mixed solution of sewage and an oxidant is introduced into the tower from the water inlet pipe; and the catalyst comprises a carrier, a multi-phase transition metal material applied on the carrier and a sulfonate group grafted on the carrier. The catalyst used in the method has a good COD digestion effect, and can maintain a good COD degradation effect and has a prominent stability in a continuous working process.

Description

TECHNICAL FIELD

[0001] The present application relates to the field of sewage treatment, in particular to a wastewater treatment method based on three-phase catalytic oxidation. BACKGROUND

[0002] Three-phase catalytic oxidation technology is an oxidation treatment method suitable for treating refractory organic wastewater. It establishes an efficient oxidation reaction system between the liquid phase (wastewater), gas phase (usually oxygen) and solid phase (catalyst), significantly improving the degradation rate and efficiency of organic matter. Specifically, the introduced oxygen is activated on the surface of the solid phase catalyst to form highly active free radicals, which have extremely strong oxidizing ability and can rapidly destroy the molecular structure of organic pollutants, converting them into harmless small molecular substances such as CO2 and H2O, thereby achieving the purpose of deep purification of water quality.

[0003] In three-phase catalytic oxidation technology, the solid phase catalyst plays a crucial role, and it usually uses a carrier loaded with multi-phase catalytic metal components. These carrier materials, such as activated carbon, titanium dioxide, zeolite, ceramic particles, etc., not only have a large specific surface area to provide abundant active sites, but also can stably load noble metals (such as platinum, palladium, ruthenium, etc.) or transition metals and their oxides, further enhancing catalytic performance. Metal components as active centers can promote the effective decomposition of oxygen to generate free radicals with strong oxidation ability, accelerating the oxidation and degradation process of organic matter.

[0004] However, due to the adsorption properties of the carrier, its surface is prone to adhere and accumulate suspended solids in wastewater. These suspended solids may include incompletely precipitated solid particles, microbial debris, and other impurities, which cover the surface of the catalyst, reducing the effective contact area of the catalyst, hindering the effective mass transfer between the gas-liquid two phases and the catalyst surface, leading to a decrease in the suspension performance of the catalyst, a decrease in reaction efficiency, and even a reduction in the service life of the catalyst. SUMMARY

[0005] To alleviate the problem of easy adhesion of pollutants to the solid phase catalyst in three-phase catalytic oxidation wastewater treatment technology, affecting the degradation efficiency and service life, the present application provides a wastewater treatment method based on three-phase catalytic oxidation.

[0006] The present application provides a wastewater treatment method based on three-phase catalytic oxidation, which uses a catalytic oxidation tower for treatment. The catalytic oxidation tower is provided with an aeration pipe and a catalyst layer from bottom to top, an inlet pipe is arranged between the aeration pipe and the catalyst layer, and an outlet pipe is arranged above the catalyst layer. The mixture of wastewater and oxidant is introduced into the tower from the inlet pipe. The catalyst includes a carrier, a multi-phase transition metal material applied to the carrier, and a sulfonate group grafted to the carrier.

[0007] The mixture of sewage and oxidant enters the tower, and when passing through the catalyst layer, a large amount of hydroxyl radicals, superoxide radicals and peroxide radicals are generated. These radicals have extremely high electronegativity and reactivity, and can react with organic pollutants in water without selectivity, attacking carbon-carbon bonds, carbon-hydrogen bonds and carbon-oxygen bonds in organic molecules, resulting in the breaking of organic molecules to form smaller, more biodegradable intermediates or final products such as water and carbon dioxide.

[0008] The present application can effectively increase the affinity and wettability of water molecules to the catalyst by introducing sulfonate groups with negative charge and polarity on the surface of the catalyst carrier. On the one hand, it is beneficial to improve the contact reaction efficiency of the catalyst with oxidants and dissolved oxygen in the water phase. On the other hand, it can increase the contact of water molecules with pollutants on the surface of the carrier, making the attachments more easily detached from the carrier and less likely to accumulate and block the carrier. It is beneficial to maintain the catalytic degradation efficiency.

[0009] More importantly, grafting the sulfonate group does not affect the degradation of macromolecular organic matter in sewage by the catalyst, and does not block the pores of the carrier. The sulfonate compound is stably connected to the carrier through chemical bonding and is not easily reacted with free radicals, having good stability.

[0010] Preferably, the catalyst surface is grafted with a pyrrolidone group.

[0011] The introduction of the pyrrolidone group has good hydrophilicity due to its nitrogen heterocyclic structure, which is beneficial to improve the dirt resistance of the catalyst and ensure its catalytic degradation efficiency. On the other hand, the nitrogen heterocyclic structure can form a protective layer on the surface of the catalyst, adsorb and chelate oxidizing metal ions in the sewage, inhibit the contact of the oxidizing metal ions with the heterogeneous metal components in the catalyst or the generated free radicals, reduce the catalyst and free radical loss caused by side reactions, and ensure the sewage treatment effect.

[0012] Preferably, the heterogeneous transition metal material comprises one or more transition metals and / or transition metal oxides.

[0013] Preferably, the raw materials of the catalyst include:

[0014] Carrier 10 parts;

[0015] Transition metal salt solution 7.5-12 parts;

[0016] Sulfonate acrylate monomer 3-5 parts;

[0017] Vinyl pyrrolidone 1-2 parts;

[0018] Radical initiator 0.05-0.1 parts;

[0019] The concentration of the transition metal salt solution is 20-30 wt%.

[0020] Preferably, the sulfonated acrylate monomer comprises at least one of sodium methallyl sulfonate, sodium allyl sulfonate, and sodium 2-propenyl sulfonate.

[0021] Preferably, the transition metal is selected from one or more of platinum, palladium, rhodium, copper, iron, manganese, cobalt, nickel, and zirconium.

[0022] Preferably, the preparation method of the catalyst comprises the following steps:

[0023] Dissolving the transition metal salt in water to prepare a transition metal salt solution with a concentration of 18-30 wt%;

[0024] Mixing the activated carbon with the transition metal salt solution under vacuum, and rotating the impregnation for 3-5 days; after the impregnation is completed, filtering the product to obtain an impregnated carrier;

[0025] Activating the impregnated carrier in an atmosphere containing 5-10 wt% oxygen at a temperature of 500-600 °C for 2-4 h, and cooling the product to obtain an activated carrier;

[0026] Dissolving the vinyl silane coupling agent in an alcohol-water mixture, adding the activated carrier, and stirring the reaction for 0.5-1 h, and filtering and washing with water to obtain a modified carrier;

[0027] Adding the modified carrier to an emulsifier solution, stirring uniformly, adding the sulfonated acrylate monomer, N-vinyl pyrrolidone, and an initiator, heating to 65-75 °C, stirring the reaction for 3-5 h, and centrifuging, washing with water, and drying to obtain the product.

[0028] Preferably, the vacuum degree after the vacuuming is -0.08 to -0.1 MPa.

[0029] Preferably, the rotating impregnation is performed in a rotating drum at a rotating speed of 1-10 revolutions / min.

[0030] Preferably, the vinyl silane coupling agent is selected from one or more of vinyl trimethoxysilane, vinyl triethoxysilane, methyl vinyl dimethoxysilane, and methyl vinyl diethoxysilane.

[0031] Preferably, the alcohol-water mixture is a mixture of a short-chain alcohol and water, and more preferably a mixture of methanol or ethanol and water.

[0032] In the preparation process of the catalyst, the carrier is first immersed in a transition metal salt solution, the drum is continuously rotated to make the metal ions fully contact and load on the surface of the carrier and in the pore structure thereof, and then high-temperature activation is performed to convert the metal ions into metal or metal oxide with catalytic activity. Then, a vinyl silane coupling agent is introduced on the surface of the carrier, and a comonomer and an initiator are added to enable the sulfonate group and the pyrrolidone group to be grafted and bonded to the surface of the carrier through a free radical copolymerization reaction, so as to improve the hydrophilic property of the catalyst.

[0033] It should be noted that the oxygen content refers to the volume percentage of oxygen. Controlling the oxygen content is beneficial to prevent the combustion reaction of the activated carbon, affect the porosity and loading rate thereof, and ensure good catalytic efficiency.

[0034] Preferably, the carrier is a pretreated activated carbon, and the pretreated activated carbon is obtained by calcining the activated carbon at a temperature of 230-300 DEG C for 0.5-1 h.

[0035] The calcination treatment of the activated carbon can increase the oxygen-containing groups in the pore structure on the surface of the activated carbon, which is helpful to improve the hydrophilic property thereof, thereby reducing the possibility of dirt accumulation on the surface of the catalyst and affecting the catalytic degradation efficiency of the organic matter. It should be noted that the increase of the calcination temperature is easy to cause the combustion reaction, resulting in the carbon loss and the collapse of the pore structure of the activated carbon, which is not conducive to improving the loading rate of the multi-phase metal component.

[0036] Preferably, the oxidizing agent is hydrogen peroxide.

[0037] Preferably, a filter packing layer is arranged between the aeration pipe and the catalyst layer.

[0038] Preferably, the filter packing is selected from one or more of the following: ceramic granules, quartz sand, gravel, zeolite and porous ceramic.

[0039] The physical filtration is helpful to filter out most of the large-particle suspended matters in the wastewater, reduce the plugging and blocking effect of the catalyst layer, and ensure the exertion of the catalytic degradation effect.

[0040] In summary, the present application has the following beneficial effects:

[0041] 1. By grafting the sulfonate group on the surface of the catalyst carrier, the probability of dirt adhesion and plugging is effectively reduced, and the service life and catalytic efficiency of the catalyst are improved.

[0042] 2. The further grafting of the pyrrolidone group can increase the hydrophilic property and inhibit the deposition of dirt, while reducing the loss of the effective catalytic component or free radical product in the catalyst caused by the oxidizing metal ions in the wastewater.

[0043] 3. Low-temperature calcination of the activated carbon carrier can increase the hydrophilicity of the carrier, thereby improving the pollution resistance, which is conducive to improving the catalytic efficiency and prolonging the service life. BRIEF DESCRIPTION OF DRAWINGS

[0044] Figure 1 is a schematic diagram of the overall structure of the catalytic oxidation tower of the present application.

[0045] BRIEF DESCRIPTION OF DRAWINGS: 1, tower body; 2, aeration pipe; 3, filter filler layer; 4, catalyst layer; 5, water inlet pipe; 6, water outlet pipe; 7, exhaust pipe. DETAILED DESCRIPTION

[0046] Preparation Example

[0047] The performance parameters of the activated carbon raw material of the present application are as follows: cylindrical activated carbon, diameter 4 mm, length 50-60 mm; bulk specific gravity 600 kg / m 3 ; specific surface area 850-900 m 2 / g; pore volume 0.42 cm 3 / g; average pore size 1.73 mm.

[0048] Preparation Example 1, catalyst, prepared according to the following steps:

[0049] The activated carbon is added to a calcination furnace, the temperature of the calcination furnace is controlled at 260±5℃, and calcination is carried out for 0.8h to obtain pretreated activated carbon.

[0050] 100g of transition metal salt is dissolved in water to prepare a transition metal salt solution with a concentration of 20wt% for standby use. The transition metal salt includes 40g of manganese nitrate, 15g of cobalt nitrate, 25g of copper nitrate and 20g of platinum nitrate.

[0051] 100g of pretreated activated carbon is added to a rotating drum, vacuumized to a vacuum degree of -0.08 to -0.1 MPa, and the above prepared transition metal salt solution is added for impregnation at 5 revolutions / min for 4d; after impregnation, the material is centrifuged and filtered to obtain an impregnated carrier.

[0052] The above obtained impregnated carrier is placed in a calcination furnace in a nitrogen atmosphere, heated to 550±5℃, and high-temperature activated for 3h; after activation, the material is cooled and discharged to obtain an activated carrier.

[0053] 50g of vinyltriethoxysilane is dissolved in 500mL of ethanol-water mixture (water content 10wt%), acetic acid is added to adjust the pH value to 4, and the above obtained activated carrier is added, stirred for 1h, filtered and washed with water three times to obtain a modified carrier.

[0054] The fatty alcohol polyoxyethylene ether was added to water and stirred to obtain a 3 wt% emulsifier solution. The modified carrier obtained above was added to 600 mL of the emulsifier solution and stirred uniformly. Then, 42 g of sodium allyl sulfonate, 16 g of 1-vinyl-2-pyrrolidone and 1 g of sodium persulfate were added. The temperature was raised to 70°C and the reaction was stirred for 4 h. The carrier was separated by centrifugal filtration, washed with deionized water and dried to obtain the desired catalyst.

[0055] Preparation Example 2, Catalyst, was prepared according to the following steps:

[0056] The activated carbon was placed in a calcination furnace and the temperature of the calcination furnace was controlled at 240±5°C. The activated carbon was calcined for 1 h to obtain a pretreated activated carbon.

[0057] 80 g of transition metal salt was dissolved in water to prepare a 25 wt% transition metal salt solution. The transition metal salt included 30 g of manganese nitrate, 10 g of cobalt nitrate, 10 g of copper nitrate, 10 g of zirconium nitrate and 20 g of platinum nitrate.

[0058] 100 g of the pretreated activated carbon was placed in a rotating drum and vacuumized to a vacuum degree of -0.08 to -0.1 MPa. The transition metal salt solution prepared above was added and the rotating drum was rotated at 5 revolutions per minute for 4 d. After the impregnation was completed, the material was separated by centrifugal filtration to obtain an impregnated carrier.

[0059] The impregnated carrier obtained above was placed in a calcination furnace in a nitrogen atmosphere and the temperature was raised to 590±5°C. The high-temperature activation was performed for 4 h. After the activation was completed, the material was cooled and discharged to obtain an activated carrier.

[0060] 30 g of vinyltriethoxysilane was dissolved in 500 mL of an ethanol-water mixture (water content 10 wt%) and acetic acid was added to adjust the pH value to 4. The activated carrier obtained above was added and the reaction was stirred for 0.5 h. After filtration, the material was washed with water three times to obtain a modified carrier.

[0061] The fatty alcohol polyoxyethylene ether was added to water and stirred to obtain a 2 wt% emulsifier solution. The modified carrier obtained above was added to 600 mL of the emulsifier solution and stirred uniformly. Then, 33 g of sodium allyl sulfonate, 20 g of 1-vinyl-2-pyrrolidone and 1 g of sodium persulfate were added. The temperature was raised to 65°C and the reaction was stirred for 5 h. The carrier was separated by centrifugal filtration, washed with deionized water and dried to obtain the desired catalyst.

[0062] Preparation Example 3, Catalyst, was prepared according to the following steps:

[0063] The activated carbon was placed in a calcination furnace and the temperature of the calcination furnace was controlled at 290±5°C. The activated carbon was calcined for 0.5 h to obtain a pretreated activated carbon.

[0064] 100 g of transition metal salt was dissolved in water to prepare a transition metal salt solution with a concentration of 20 wt% for later use. The transition metal salt included 35 g of manganese nitrate, 35 g of copper nitrate, 15 g of zirconium nitrate and 15 g of platinum nitrate.

[0065] 100 g of the pretreated activated carbon was added into a rotating drum, vacuumized to a vacuum degree of -0.08 to -0.1 MPa, and the transition metal salt solution prepared above was added to impregnate for 5 days at a rotation speed of 3 rpm. After the impregnation, the impregnated carrier was obtained by centrifugal filtration.

[0066] The impregnated carrier obtained above was placed in a nitrogen atmosphere calcination furnace, heated to 510 ± 5 °C, and activated for 4 hours at high temperature. After the activation, the activated carrier was obtained by cooling and discharging.

[0067] 60 g of vinyltriethoxysilane was dissolved in 600 mL of an ethanol-water mixture (water content 10 wt%), and acetic acid was added to adjust the pH value to 5. The activated carrier obtained above was added, and stirred for 0.5 hours. After filtration, the modified carrier was obtained by washing with water three times.

[0068] The fatty alcohol polyoxyethylene ether was added to water and stirred to prepare a 3 wt% emulsifier solution. The modified carrier obtained above was added to 800 mL of the emulsifier solution, stirred uniformly, and 42 g of sodium methallyl sulfonate, 16 g of 1-vinyl-2-pyrrolidone and 1 g of sodium persulfate were added. The temperature was raised to 70 °C, and stirred for 4 hours. The carrier was obtained by centrifugal filtration, washed with deionized water, and dried to obtain the desired catalyst.

[0069] Preparation Example 4, Catalyst, which is different from Preparation Example 1 in that an equal amount of sodium allyl sulfonate is used instead of 1-vinyl-2-pyrrolidone.

[0070] Preparation Example 5, Catalyst, which is different from Preparation Example 1 in that an equal amount of aminopropyltriethoxysilane is used instead of vinyltriethoxysilane.

[0071] Preparation Example 6, Catalyst, which is different from Preparation Example 1 in that, in the step of preparing the pretreated activated carbon, the calcination temperature is controlled to 330 ± 5 °C.

[0072] Preparation Example 7, Catalyst, which is different from Preparation Example 1 in that, in the step of preparing the pretreated activated carbon, the calcination temperature is controlled to 200 ± 5 °C.

[0073] Preparation Example 8, Catalyst, which is different from Preparation Example 1 in that the activated carbon pretreatment process is not performed, and the activated carbon that has not been pretreated is used in the transition metal salt solution impregnation process.

[0074] Preparation Example 9, Catalyst, which is prepared according to the following steps:

[0075] 100g transition metal salt was dissolved in water to prepare a transition metal salt solution with a concentration of 20wt%. The transition metal salt includes 40g manganese nitrate, 15g cobalt nitrate, 25g copper nitrate and 20g platinum nitrate.

[0076] 100g pretreated activated carbon was added into a rotating drum, vacuumed to a vacuum degree of -0.08 to -0.1 MPa, and the transition metal salt solution prepared above was added. The rotating drum was rotated at 5 revolutions per minute for impregnation for 4 days. After impregnation, the impregnated carrier was obtained by centrifugal filtration.

[0077] The impregnated carrier obtained above was placed in a nitrogen atmosphere calcination furnace, heated to 550±5℃, and high-temperature activated for 3 hours. After activation, the activated carrier was obtained by cooling and discharging.

[0078] 50g vinyltriethoxysilane was dissolved in 500mL ethanol water mixture (water content 10wt%), and acetic acid was added to adjust the pH value to 4. The activated carrier obtained above was added, stirred for 1 hour, and then filtered and washed with water three times to obtain the modified carrier.

[0079] Fatty alcohol polyoxyethylene ether was added to water and stirred to prepare a 3wt% emulsifier solution. The modified carrier obtained above was added to 600mL of the emulsifier solution, stirred uniformly, and 58g of 1-vinyl-2-pyrrolidone and 1g of sodium persulfate were added. The temperature was raised to 70℃, and the mixture was stirred for 4 hours. The carrier was obtained by centrifugal filtration, washed with deionized water, and dried to obtain the desired catalyst.

[0080] Preparation Example 10, Catalyst, was prepared according to the following steps:

[0081] 100g transition metal salt was dissolved in water to prepare a transition metal salt solution with a concentration of 20wt%. The transition metal salt includes 40g manganese nitrate, 15g cobalt nitrate, 25g copper nitrate and 20g platinum nitrate.

[0082] 100g pretreated activated carbon was added into a rotating drum, vacuumed to a vacuum degree of -0.08 to -0.1 MPa, and the transition metal salt solution prepared above was added. The rotating drum was rotated at 5 revolutions per minute for impregnation for 4 days. After impregnation, the impregnated carrier was obtained by centrifugal filtration.

[0083] The impregnated carrier obtained above was placed in a nitrogen atmosphere calcination furnace, heated to 550±5℃, and high-temperature activated for 3 hours. After activation, the activated carrier was obtained by cooling and discharging.

[0084] Example

[0085] Example 1

[0086] A wastewater treatment method based on three-phase catalytic oxidation, specifically using a catalytic oxidation tower for treatment. See Figure 1The catalytic oxidation tower comprises a tower body 1, an aeration pipe 2 connected to the bottom of the tower body 1, an exhaust pipe 7 connected to the top of the tower body 1, a water inlet pipe 5 and a water outlet pipe 6 connected to the side wall of the tower body. The tower body 1 is sequentially provided with a first grid plate and a second grid plate from bottom to top, the first grid plate is filled with quartz sand to form a filter filler layer 3, and the second grid plate is filled with the catalyst obtained in Preparation Example 1 to form a catalyst layer 4. The water inlet pipe 5 is located below the first grid plate, and the water outlet pipe 6 is located above the second grid plate. The wastewater mixed with H2O2 (the concentration of H2O2 is 100 ppm) enters the tower body 1 from the water inlet pipe 5, and at the same time, air is introduced into the wastewater through the aeration pipe 2. The wastewater sequentially passes through the filter filler layer 3 and the catalyst layer 4 and is discharged from the water outlet pipe 6 of the catalytic oxidation tower. In the process, the COD of the wastewater is 700-800 mg / L, and the residence treatment time after each water inlet is 2 h. Cr

[0087] Example 2

[0088] A wastewater treatment method based on three-phase catalytic oxidation, which is different from Example 1 in that an equal amount of the catalyst obtained in Preparation Example 2 is used to replace the catalyst obtained in Preparation Example in the catalyst layer.

[0089] Example 3

[0090] A wastewater treatment method based on three-phase catalytic oxidation, which is different from Example 1 in that an equal amount of the catalyst obtained in Preparation Example 3 is used to replace the catalyst obtained in Preparation Example in the catalyst layer.

[0091] Example 4

[0092] A wastewater treatment method based on three-phase catalytic oxidation, which is different from Example 1 in that an equal amount of the catalyst obtained in Preparation Example 4 is used to replace the catalyst obtained in Preparation Example in the catalyst layer.

[0093] Example 5

[0094] A wastewater treatment method based on three-phase catalytic oxidation, which is different from Example 1 in that an equal amount of the catalyst obtained in Preparation Example 5 is used to replace the catalyst obtained in Preparation Example in the catalyst layer.

[0095] Example 6

[0096] A wastewater treatment method based on three-phase catalytic oxidation, which is different from Example 1 in that an equal amount of the catalyst obtained in Preparation Example 6 is used to replace the catalyst obtained in Preparation Example in the catalyst layer.

[0097] Example 7

[0098] A wastewater treatment method based on three-phase catalytic oxidation, which is different from Example 1 in that an equal amount of the catalyst obtained in Preparation Example 7 is used to replace the catalyst obtained in Preparation Example in the catalyst layer.

[0099] ​Example 8

[0100] A wastewater treatment method based on three-phase catalytic oxidation, which differs from Example 1 in that the catalyst layer uses an equal amount of the catalyst obtained in Preparation Example 8 instead of the catalyst obtained in Preparation Example.

[0101] Comparative Example

[0102] Comparative Example 1

[0103] A wastewater treatment method based on three-phase catalytic oxidation, which differs from Example 1 in that the catalyst layer uses an equal amount of the catalyst obtained in Preparation Example 9 instead of the catalyst obtained in Preparation Example.

[0104] Comparative Example 2

[0105] A wastewater treatment method based on three-phase catalytic oxidation, which differs from Example 1 in that the catalyst layer uses an equal amount of the catalyst obtained in Preparation Example 10 instead of the catalyst obtained in Preparation Example.

[0106] Performance test

[0107] Test 1: COD removal rate test of wastewater

[0108] According to the provisions of GB11914-89 "Determination of Chemical Oxygen Demand in Water by Dichromate Method", the COD content of the effluent from the catalytic oxidation tower for the 1st, 3rd, 5th, and 10th times was determined, and the COD removal rate was calculated.

[0109] Table 1, test results

[0110]

[0111] Analysis of test results:

[0112] 1. As can be seen from Examples 1-8 and Comparative Examples 1-2 and Table 1, the catalyst with grafted sulfonate groups on the surface has more excellent COD degradation effect after multiple wastewater treatments, and its stability and long-term performance of catalytic performance are more outstanding than those of the catalyst without grafting. The reason may be that the sulfonate groups can be stably grafted and bonded to the surface of the carrier, which can give the catalyst good hydrophilicity, easy to be wetted by water molecules, thereby facilitating the removal of deposits attached to the surface of the catalyst, reducing the coverage of the carrier surface and the blockage of the pores, and affecting the COD catalytic degradation rate.

[0113] 2、Combined with Example 1 and Example 4 and combined with Table 1, it can be seen that grafting pyrrolidone groups on the surface of the catalyst is beneficial to improve the degradation rate of COD in wastewater; combined with Comparative Example 1, it can be seen that replacing the sulfonate group with a pyrrolidone group reduces the degradation of the catalyst, especially the long-term degradation. The reason may be that pyrrolidone has certain hydrophilicity, which is beneficial to reduce the deposition and coverage of dirt; at the same time, it can chelate metal ions to block their contact reaction with catalytic metals or free radicals, thereby improving the degradation rate. However, compared with the sulfonate group, its hydrophilicity is poor, and its use alone is not conducive to ensuring the long-term degradation of the catalyst.

[0114] 3、Combined with Example 1 and Example 5 and combined with Table 1, it can be seen that before grafting the sulfonate group and the pyrrolidone group, surface treatment of the carrier with a vinyl silane coupling agent is beneficial to ensure the degradation effect of the catalyst. The reason may be that the vinyl silane coupling agent can introduce vinyl groups on the surface of the catalyst carrier, which can participate in copolymerization, improve the grafting rate of the sulfonate and pyrrolidone groups, and ensure the hydrophilic effect of the catalyst.

[0115] 4、Combined with Example 1 and Examples 6-8 and combined with Table 1, it can be seen that calcining the activated carbon carrier at low temperature is beneficial to improve its hydrophilicity, and thus improve its long-term catalytic degradation effect. The reason may be that low-temperature calcination can introduce more oxygen-containing polar functional groups on the surface and in the pores of the activated carbon, thereby improving the wettability and affinity of the carrier to water molecules.

[0116] This specific embodiment is only an explanation of the present application, and is not a limitation of the present application. Those skilled in the art can make modifications to the present embodiment without creative contribution after reading the present specification, but as long as the modifications are within the scope of the claims of the present application, they are protected by the Patent Law.

Claims

1. A wastewater treatment method based on three-phase catalytic oxidation, characterized by, The catalytic oxidation tower is used for treatment, wherein an aeration pipe and a catalyst layer are arranged from bottom to top in the catalytic oxidation tower, a water inlet pipe is arranged between the aeration pipe and the catalyst layer, and a water outlet pipe is arranged above the catalyst layer; a mixture of sewage and an oxidant is fed into the tower through the water inlet pipe; the catalyst comprises a carrier, a multi-phase transition metal material applied to the carrier, and a sulfonate group and a pyrrolidone group grafted to the carrier; the raw materials of the catalyst include, in mass parts, 10 parts of the carrier, 7.5-12 parts of a transition metal salt solution, 3-6 parts of a vinyl silane coupling agent, 3-5 parts of a sulfonate acrylate monomer, 1-2 parts of N-vinyl pyrrolidone, and 0.05-0.1 parts of a free radical initiator; The preparation method of the catalyst comprises the following operations: The transition metal salt is dissolved in water to prepare a transition metal salt solution with a concentration of 20-25 wt%; The activated carbon is mixed with the transition metal salt solution under vacuum, and the impregnation is rotated for 3-5 days; after the impregnation is completed, the material is filtered out to obtain an impregnated carrier; The impregnated carrier is activated at a temperature of 500-600 ℃ in a nitrogen atmosphere for 2-4 hours, and the material is cooled to obtain an activated carrier; The vinyl silane coupling agent is dissolved in an alcohol-water mixture, the activated carrier is added, and the reaction is stirred for 0.5-1 hour; the modified carrier is obtained by filtering and washing with water; The modified carrier is added to an emulsifier solution, stirred uniformly, and the sulfonate acrylate monomer, N-vinyl pyrrolidone, and initiator are added; the temperature is raised to 65-75 ℃, the reaction is stirred for 3-5 hours, and centrifugation, water washing, and drying are performed.

2. The method of claim 1, wherein, The multi-phase transition metal material comprises one or more transition metals and / or transition metal oxides.

3. The method of claim 1, wherein, The sulfonate acrylate monomer comprises at least one of sodium methacrylate sulfonate, sodium allyl sulfonate, and sodium 2-propylene sulfonate.

4. The method of claim 2, wherein, The transition metal is selected from one or more of platinum, palladium, rhodium, copper, iron, manganese, cobalt, nickel, and zirconium.

5. The method of claim 1, wherein, The carrier is a pretreated activated carbon, which is obtained by calcining activated carbon at a temperature of 230-300 ℃ for 0.5-1 hour.

6. The method of claim 1, wherein, The oxidant is hydrogen peroxide.

7. The method of claim 1, wherein, A filter packing layer is arranged between the aeration pipe and the catalyst layer.

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