Preparation method of supported fenton-like catalyst and application thereof in tda wastewater treatment

Abstract

The application discloses a preparation method of a supported Fenton-like catalyst and application of the catalyst in TDA wastewater treatment. The catalyst comprises a carrier and an active component. The carrier is CuFe2O4 doped with Ce and Nd, and the active component is sulfidized nano zero-valent iron. When the catalyst is applied in TDA wastewater treatment, TDA can be broken into small molecular acids, or even mineralized into carbon dioxide and water, so that the biochemical property of the wastewater is greatly improved, and no secondary pollution is caused.

Description

Technical Field

[0001] This invention belongs to the technical field of supported Fenton-like catalysts, and specifically relates to a method for preparing a supported Fenton-like catalyst and its application in TDA wastewater treatment. Background Technology

[0002] 2,4-Diaminotoluene (TDA) is a pale yellow solid at room temperature with an ammonia odor. It is soluble in water, ethanol, and ether. TDA is mainly used as a raw material for toluene diisocyanate (TDI) and as an initiator for polyethers. It can also be used as a curing agent for epoxy resins and a dye intermediate. Furthermore, it can be used to synthesize aromatic diamine curing agents for polyurethane elastomers and epoxy resins, such as dimethylthiotoluene diamine (DMTDA) and diethyltoluene diammonium (DETDA).

[0003] TDA is classified as a recalcitrant and toxic substance in the field of wastewater treatment.

[0004] In practical engineering projects involving TDA-containing wastewater, pretreatment combined with biological treatment is the primary approach. However, conventional physicochemical and biological treatment methods often fail to achieve satisfactory results. While Fenton technology is a mature and conventional pretreatment process, its slow reaction rate, low hydrogen peroxide utilization, incomplete organic matter degradation, excessive iron sludge production, and high treatment costs still limit its industrial application. Fenton-like technologies, as alternatives to Fenton technology, offer significant advantages in catalytic reaction rate and hydrogen peroxide utilization, and the reaction does not produce iron sludge, thus significantly reducing treatment costs. Summary of the Invention

[0005] The purpose of this invention is to provide a method for preparing a supported Fenton-like catalyst, which has a fast reaction rate, high hydrogen peroxide utilization, simple preparation, wide range of application conditions, low metal loss, and does not cause secondary pollution.

[0006] Another objective of this invention is to provide a method for treating TDA wastewater that is highly efficient and simple to implement.

[0007] To achieve the above objectives, the technical solution adopted by the present invention is as follows:

[0008] A supported Fenton-like catalyst, comprising: a Ce and Nd-doped CuFe₂O₄ support and an active component, sulfide nano-zero-valent iron (S-NZVI), supported on the support, denoted as Ce. x Nd y CuFe (2-x-y)O4 / S-NZVI, where x is 0.01-0.05, y is 0.01-0.05, the mass ratio of iron in the carrier to iron in the active component S-NZVI is 0.7:1-5:1, and the molar ratio of sulfur to iron in S-NZVI is 0.2-0.6:1.

[0009] This invention provides a method for preparing the supported Fenton-like catalyst, comprising the following steps:

[0010] (1) Ce and Nd-doped catalyst supports were prepared by the sol-gel method. x Nd y CuFe (2-x-y) O4:

[0011] According to the stoichiometric ratio, cerium salt, neodymium salt, copper nitrate, and ferric nitrate were weighed and dissolved in water to form precursor solution A;

[0012] The complexing agent is dissolved in deionized water to form precursor solution B;

[0013] Precursor solution B was added dropwise to precursor solution A under water bath stirring, and the pH was adjusted to neutral with alkali solution until the solution reached a sol state. The sol was dried, ground, and the precursor powder was obtained. Then, it was calcined to obtain the carrier Ce. x Nd y CuFe (2-x-y) O4.

[0014] (2)Ce x Nd y CuFe (2-x-y) Preparation of O4-supported sulfide nano-zero valent iron:

[0015] Ce in a nitrogen atmosphere x Nd y CuFe (2-x-y) O4 and Na2S2O4 are placed in a mixed solution of FeSO4 in ethanol and water (preferably mixed in a 1:1 ratio) and mixed evenly, so that the molar ratio of S in Na2S2O4 to Fe in FeSO4 is controlled at 0.2-0.6:1. Then, NaBH4 solution is added dropwise through a separatory funnel and stirred evenly.

[0016] (3) The solid was cleaned several times by alternating between oxygen-free and anhydrous ethanol and oxygen-free water. Finally, the solid was dried in an oven to obtain the catalyst of the present invention. The dried catalyst sample was put back into the glove box for grinding and later use.

[0017] Preferably, in step (1), the cerium salt is at least one selected from cerium nitrate, cerium oxalate, cerium acetate, and cerium chloride.

[0018] The neodymium salt is at least one of neodymium nitrate, neodymium carbonate, neodymium chloride, and neodymium isooctanoate;

[0019] Preferably, in step (1), the complexing agent is one of citric acid, tartaric acid, maleic acid, diethanolamine, triethanolamine, and sodium ethylenediaminetetraacetate;

[0020] Preferably, in step (1), the molar ratio of the metal elements in the cerium salt, neodymium salt, copper nitrate, and ferric nitrate is 0.01-0.05:0.01-0.05:1:1.98-1.9.

[0021] The molar ratio of the total molar amount of cerium, neodymium, copper, and iron to the molar amount of the complexing agent is 1:0.8-1.6.

[0022] Preferably, in step (1), the alkaline solution is at least one of ammonia, sodium hydroxide, potassium hydroxide, sodium acetate, and potassium acetate.

[0023] Preferably, in step (1), the calcination conditions are calcination at 300-500℃ for 2-5 hours.

[0024] Preferably, in step (2), the concentration of the sodium borohydride solution is 0.05-0.25 mol / L, and the dosage is sufficient to completely reduce FeSO4.

[0025] This invention also relates to the application of the above-mentioned catalyst in TDA wastewater treatment.

[0026] A method for treating TDA wastewater includes the following steps:

[0027] (1) Adjust the pH of TDA wastewater to 3-12, and then react it with hydrogen peroxide under the action of the catalyst of the present invention;

[0028] (2) After the reaction in step (1), the generated waste gas is sent to the waste gas incinerator for treatment.

[0029] Preferably, the oxidation reaction temperature in step (1) is 30-80℃;

[0030] Preferably, the mass hourly space velocity (MSV) of the wastewater in step (1) is in the range of 0.2-1 h⁻¹. -1 The stay is 1-5 hours.

[0031] Preferably, in step (1), the molar ratio of hydrogen peroxide to COD in TDA wastewater is 0.5 to 3.0:1.

[0032] The TDA wastewater refers to the wastewater generated during the production of 2,4-diaminotoluene, which contains approximately 200-500 ppm TDA and 5000-8000 ppm COD.

[0033] Compared with the prior art, the present invention has at least the following beneficial effects:

[0034] (1) The supported Fenton-like catalyst prepared in this invention is prepared by Ce and Nd co-doped CuFe2O4 via the sol-gel method. The co-doping of Ce and Nd improves the reactive sites and redox potential of the catalyst support, further enhancing the catalytic activity of the catalyst. It can mutually promote the reaction with the active component, sulfide nano-zero-valent iron, through Ce… x Nd y CuFe (2-x-y) The synergistic effect between O4 and S-NZVI significantly increases the reactive sites of the catalyst and enhances its catalytic activity.

[0035] (2) The supported Fenton-like catalyst prepared in this invention is used to treat TDA wastewater. The TDA in the wastewater is oxidized into small molecule acids or even mineralized into CO2 and H2O by hydrogen peroxide oxidation. The reaction rate is fast, the hydrogen peroxide utilization rate is high, the preparation is simple, the application conditions are wide, and the metal loss is small.

[0036] (3) The supported Fenton-like catalyst prepared in this invention is applicable to TDA wastewater treatment as well as other difficult-to-biodegrade wastewater. Detailed Implementation

[0037] To make the objectives, technical solutions, and advantages of the embodiments of the present invention clearer, the technical solutions in the embodiments of the present invention will be clearly and completely described below in conjunction with the embodiments of the present invention. Obviously, the described embodiments are only some embodiments of the present invention, not all embodiments. The following detailed description of the embodiments of the present invention is not intended to limit the scope of the claimed invention, but merely to illustrate selected embodiments of the invention. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0038] TDA wastewater: The TDA content is approximately 500 ppm, and the COD is 8000 ppm. It is organic wastewater generated during the TDA production process at Wanhua Chemical's TDA plant.

[0039] Example 1: Catalyst 1

[0040] A method for preparing a supported Fenton-like catalyst includes the following steps:

[0041] (1) According to Ce 0.01 Nd 0.01 CuFe 1.98 O4 stoichiometrically weigh out cerium nitrate, neodymium nitrate, copper nitrate, and ferric nitrate, dissolve them in water to form precursor solution A;

[0042] (2) Dissolve citric acid in deionized water to form precursor solution B;

[0043] (3) 0.8 mol (referring to the molar amount of citric acid, the same in the following examples) of precursor solution B was added dropwise to 1 mol (referring to the total molar amount of cerium, neodymium, copper, and iron, the same in the following examples) of precursor solution A. The dropwise addition was carried out under water bath stirring and the pH was adjusted to neutral with ammonia water until the solution was in a sol state. The sol obtained from the reaction was dried, ground, and the precursor powder was obtained. The precursor powder was calcined at 400°C for 3 h to obtain the monomer Ce. 0.01 Nd 0.01 CuFe 1.98 O4.

[0044] (4)Ce 0.01 Nd 0.01 CuFe 1.98 Preparation of O4-supported sulfide nano-zero-valent iron: 4g Ce was added under a nitrogen atmosphere. 0.01 Nd 0.01 CuFe 1.98 O4 and 0.2 g Na2S2O4 were placed in 250 mL of a mixed solution of ethanol and water with a FeSO4 concentration of 0.04 mol / L and mixed thoroughly to make the S / Fe molar ratio approximately 0.2:1. Then, 250 mL of 0.08 mol / L NaBH4 solution was added dropwise using a separatory funnel and stirred thoroughly.

[0045] (5) The solid was cleaned several times by alternating between oxygen-free and anhydrous ethanol and oxygen-free water. Finally, the solid was dried in an oven. The dried sample was then placed back into the glove box for grinding and ready for use.

[0046] Example 2: Catalyst 2

[0047] A method for preparing a supported Fenton-like catalyst includes the following steps:

[0048] (1) According to Ce 0.02 Nd 0.02 CuFe 1.96 O4 stoichiometrically weighed cerium oxalate, neodymium carbonate, copper nitrate, and ferric nitrate, and dissolved them in water to form precursor solution A.

[0049] (2) Dissolve tartaric acid in deionized water to form precursor solution B;

[0050] (3) 1.0 mol of precursor solution B was added dropwise to 1 mol of precursor solution A. The dropwise addition was carried out under water bath stirring and the pH was adjusted to neutral with sodium hydroxide until the solution was in a sol state. The sol obtained from the reaction was dried, ground, and the precursor powder was obtained. The precursor powder was then calcined at 400℃ for 3 h to obtain the monomer Ce. 0.02 Nd0.02 CuFe 1.96 O4.

[0051] (4)Ce 0.02 Nd 0.02 CuFe 1.96 Preparation of O4-supported sulfide nano-zero-valent iron: 4g Ce was added under a nitrogen atmosphere. 0.02 Nd 0.02 CuFe 1.96 O4 and 0.52g Na2S2O4 were placed in 250mL of a mixed solution of ethanol and water with a FeSO4 concentration of 0.04mol / L and mixed thoroughly to achieve a S / Fe molar ratio of 0.6:1. Then, 250mL of 0.08mol / L NaBH4 solution was added dropwise through a separatory funnel and stirred until homogeneous.

[0052] (5) The solid was cleaned several times by alternating between oxygen-free and anhydrous ethanol and oxygen-free water. Finally, the solid was dried in an oven. The dried sample was then placed back into the glove box for grinding and ready for use.

[0053] Example 3: Catalyst 3

[0054] A method for preparing a supported Fenton-like catalyst includes the following steps:

[0055] (1) According to Ce 0.03 Nd 0.03 CuFe 1.94 O4 stoichiometrically weigh out cerium acetate, neodymium chloride, copper nitrate, and ferric nitrate, dissolve them in water to form precursor solution A.

[0056] (2) Dissolve maleic acid in deionized water to form precursor solution B;

[0057] (3) 1.2 mol of precursor solution B was added dropwise to 1 mol of precursor solution A. The dropwise addition was carried out under water bath stirring and the pH was adjusted to neutral with potassium hydroxide until the solution was in a sol state. The resulting sol was dried, ground, and the precursor powder was obtained. The precursor powder was then calcined at 400℃ for 3 h to obtain the monomer Ce. 0.03 Nd 0.03 CuFe 1.94 O4.

[0058] (4)Ce 0.03 Nd 0.03 CuFe 1.94 Preparation of O4-supported sulfide nano-zero valent iron: 5g Ce was added under a nitrogen atmosphere... 0.03 Nd 0.03 CuFe 1.94O4 and 0.5g Na2S2O4 were placed in 250mL of a mixed solution of ethanol and water with a FeSO4 concentration of 0.06mol / L and mixed thoroughly to make the S / Fe molar ratio approximately 0.4:1. Then, 150mL of 0.2mol / L NaBH4 solution was added dropwise through a separatory funnel and stirred until homogeneous.

[0059] (5) The solid was cleaned several times by alternating between oxygen-free and anhydrous ethanol and oxygen-free water. Finally, the solid was dried in an oven. The dried sample was then placed back into the glove box for grinding and ready for use.

[0060] Example 4: Catalyst 4

[0061] A method for preparing a supported Fenton-like catalyst includes the following steps:

[0062] (1) According to Ce 0.04 Nd 0.04 CuFe 1.92 O4 stoichiometrically weigh out cerium chloride, neodymium isooctanoate, copper nitrate, and ferric nitrate, dissolve them in water to form precursor solution A.

[0063] (2) Dissolve diethanolamine in deionized water to form precursor solution B;

[0064] (3) 1.6 mol of precursor solution B was added dropwise to 1 mol of precursor solution A. The addition was carried out under water bath stirring and the pH was adjusted to neutral with sodium acetate until the solution was in a sol state. The sol obtained from the reaction was dried, ground, and the precursor powder was obtained. The precursor powder was then calcined at 400℃ for 3 h to obtain the monomer Ce. 0.04 Nd 0.04 CuFe 1.92 O4.

[0065] (4)Ce 0.04 Nd 0.04 CuFe 1.92 Preparation of O4-supported sulfide nano-zero-valent iron: 4g Ce was added under a nitrogen atmosphere. 0.04 Nd 0.04 CuFe 1.92 O4 and 0.32g Na2S2O4 were placed in 250mL of a mixed solution of ethanol and water with a FeSO4 concentration of 0.03mol / L and mixed thoroughly to achieve a S / Fe molar ratio of 0.5:1. Then, 100mL of 0.15mol / L NaBH4 solution was added dropwise through a separatory funnel and stirred until homogeneous.

[0066] (5) The solid was cleaned several times by alternating between oxygen-free and anhydrous ethanol and oxygen-free water. Finally, the solid was dried in an oven. The dried sample was then placed back into the glove box for grinding and ready for use.

[0067] Example 5

[0068] Application of supported Fenton-like catalysts in the treatment of TDA wastewater (Catalyst 1)

[0069] The pH of the TDA wastewater was adjusted to 3, and it reacted with hydrogen peroxide under the action of catalyst 1. The reaction temperature was 40℃, the residence time was 1 h, and the wastewater mass hourly space velocity was 1 h⁻¹. -1 The molar ratio of hydrogen peroxide to COD in TDA wastewater is 1.5:1. The effluent COD is 5254 mg / L.

[0070] Example 6

[0071] Application of supported Fenton-like catalysts in the treatment of TDA wastewater (Catalyst 2)

[0072] The pH of the TDA wastewater was adjusted to 7, and it reacted with hydrogen peroxide in the presence of catalyst 2. The reaction temperature was 40℃, the residence time was 2 hours, and the wastewater mass hourly space velocity was 0.5 h⁻¹. -1 The molar ratio of hydrogen peroxide to COD in TDA wastewater is 1:1. The effluent COD is 4325 mg / L.

[0073] Example 7

[0074] Application of supported Fenton-like catalysts in the treatment of TDA wastewater (Catalyst 3)

[0075] The pH of the TDA wastewater was adjusted to 9, and it reacted with hydrogen peroxide in the presence of catalyst 3. The reaction temperature was 60℃, the residence time was 3 hours, and the wastewater mass hourly space velocity was 0.3 h⁻¹. -1 The molar ratio of hydrogen peroxide to COD in TDA wastewater is 1.5:1. The effluent COD is 3874 mg / L.

[0076] Example 8

[0077] Application of supported Fenton-like catalysts in the treatment of TDA wastewater (Catalyst 4)

[0078] The pH of the TDA wastewater was adjusted to 9, and it reacted with hydrogen peroxide in the presence of catalyst 4. The reaction temperature was 50℃, the residence time was 5 hours, and the wastewater mass hourly space velocity (MHSV) was 0.2 h⁻¹. -1 The molar ratio of hydrogen peroxide to COD in TDA wastewater is 2:1. The effluent COD is 2420 mg / L.

[0079] Comparative Example 1

[0080] A method for preparing a supported Fenton-like catalyst includes the following steps:

[0081] (1) Weigh out copper nitrate and ferric nitrate according to the stoichiometric ratio of CuFe2O4 and dissolve them in water to form precursor solution A.

[0082] (2) Dissolve tartaric acid in deionized water to form precursor solution B;

[0083] (3) 1.0 mol of precursor solution B was added dropwise to 1 mol of precursor solution A. The dropwise addition was carried out under water bath stirring and the pH was adjusted to neutral with sodium hydroxide until the solution was in a sol state. The sol obtained from the reaction was dried and ground to obtain precursor powder. The precursor powder was calcined at 400℃ for 3 h to obtain monomer CuFe2O4.

[0084] (4) Preparation of CuFe2O4-supported sulfide nano-zero-valent iron: Under a nitrogen atmosphere, 4g CuFe2O4 and 0.2g Na2S2O4 were placed in a 250mL mixture of ethanol and water with a FeSO4 concentration of 0.04mol / L and mixed thoroughly to achieve an S / Fe molar ratio of 0.2:1. Then, 250mL of 0.08mol / L NaBH4 solution was added dropwise using a separatory funnel and stirred until homogeneous.

[0085] (5) The solid was cleaned several times by alternating between oxygen-free and anhydrous ethanol and oxygen-free water. Finally, the solid was dried in an oven. The dried sample was then placed back into the glove box for grinding and ready for use.

[0086] Wastewater was treated under the same conditions as in Example 5, resulting in an effluent COD of 6550 mg / L. This comparative example demonstrates that Ce and Nd doping can enhance the activity of the support, ensuring efficient reaction.

[0087] Comparative Example 2

[0088] A method for preparing a doped Fenton-like catalyst includes the following steps:

[0089] (1) According to Ce 0.03 Nd 0.03 CuFe 1.94 O4 stoichiometrically weigh out cerium acetate, neodymium chloride, copper nitrate, and ferric nitrate, dissolve them in water to form precursor solution A.

[0090] (2) Dissolve maleic acid in deionized water to form precursor solution B;

[0091] (3) 1.2 mol of precursor solution B was added dropwise to 1 mol of precursor solution A. The dropwise addition was carried out under water bath stirring and the pH was adjusted to neutral with potassium hydroxide until the solution was in a sol state. The resulting sol was dried, ground, and the precursor powder was obtained. The precursor powder was then calcined at 400℃ for 3 h to obtain the monomer Ce. 0.03 Nd 0.03 CuFe 1.94 O4.

[0092] (4) The solid was cleaned several times by alternating between oxygen-free and anhydrous ethanol and oxygen-free water. Finally, the solid was dried in an oven. The dried sample was then placed back into the glove box for grinding and ready for use.

[0093] Wastewater was treated under the same conditions as in Example 7, and the effluent COD was only 7062 mg / L. This comparative example demonstrates that the loading of S-NZVI can significantly enhance the catalyst activity and promote the rapid progress of the Fenton reaction.

Claims

1. A supported Fenton-like catalyst, characterized in that, The catalyst comprises: a Ce and Nd-doped CuFe2O4 support and an active component, sulfide nano-zero-valent iron, supported on the support, denoted as Ce. x Nd y CuFe (2-x-y) O4 / S-NZVI; Where x is 0.01-0.05 and y is 0.01-0.05; In S-NZVI, the molar ratio of sulfur to iron is 0.2-0.6:

1.

2. The supported Fenton-like catalyst according to claim 1, characterized in that, The mass ratio of iron in the carrier to iron in the active component S-NZVI is 0.7:1-5:

1.

3. A method for preparing a supported Fenton-like catalyst as described in claim 1 or 2, comprising the following steps: (1) Weigh out cerium salt, neodymium salt, copper nitrate and ferric nitrate according to stoichiometric ratio and dissolve them in water to form precursor solution A; The complexing agent is dissolved in deionized water to form precursor solution B; Precursor solution B was mixed with precursor solution A, and the pH was adjusted to neutral with alkali solution during the mixing process until the solution reached a sol state. The sol was dried, ground, and the precursor powder was obtained. Then, the powder was calcined to obtain the carrier Ce. x Nd y CuFe (2-x-y) O4; (2) Ce x Nd y CuFe (2-x-y) O4 and Na2S2O4 are placed in a FeSO4 solution and mixed evenly, then NaBH4 solution is added and stirred evenly. (3) The obtained solid is dried to obtain the catalyst.

4. The preparation method according to claim 3, wherein, In step (1), the cerium salt is at least one of cerium nitrate, cerium oxalate, cerium acetate, and cerium chloride. The neodymium salt is at least one of neodymium nitrate, neodymium carbonate, neodymium chloride, and neodymium isooctanoate; The complexing agent is at least one of citric acid, tartaric acid, maleic acid, diethanolamine, triethanolamine, and sodium ethylenediaminetetraacetate.

5. The preparation method according to claim 3 or 4, wherein, In step (1), the molar ratio of the metal elements in the cerium salt, neodymium salt, copper nitrate, and ferric nitrate is 0.01-0.05:0.01-0.05:1:1.98-1.

9. The molar ratio of the total molar amount of cerium, neodymium, copper, and iron to the molar amount of the complexing agent is 1:0.8-1.

6.

6. The preparation method according to any one of claims 3-4, wherein, In step (1), the alkaline solution is at least one of ammonia, sodium hydroxide, potassium hydroxide, sodium acetate, and potassium acetate.

7. The preparation method according to claim 3, wherein, In step (2), the molar ratio of S in Na2S2O4 to Fe in FeSO4 is controlled at 0.2-0.6:

1.

8. The preparation method according to claim 3, wherein, The mass ratio of iron in the carrier to Fe in FeSO4 is 0.7:1-5:

1.

9. A method for treating TDA wastewater, comprising: The pH of the TDA wastewater is adjusted to 3-12, and it undergoes an oxidation reaction with hydrogen peroxide under the action of the catalyst described in claim 1 or 2 or the catalyst prepared by the method according to any one of claims 3-8.

10. The processing method according to claim 9, wherein, The oxidation reaction temperature is 30-80℃; The mass hourly space velocity (MSV) of the wastewater ranges from 0.2 to 1 h⁻¹. -1 The stay is 1-5 hours. The molar ratio of hydrogen peroxide to COD in TDA wastewater is 0.5–3.0:

1.

11. The processing method according to claim 9 or 10, wherein, The TDA wastewater contains 200-500 ppm TDA and 5000-8000 ppm COD.