Multi-stage oxidation treatment method for petroleum refining waste alkali liquor

Abstract

The invention discloses a multistage oxidation treatment method of petroleum refining waste lye, and belongs to the technical field of hazardous waste treatment.The multistage oxidation treatment method comprises the steps that 1, ZnSx at-Fe3O4 / MIL-100 (Fe) and a chlorate-containing oxidizing agent solution are added into the waste lye, a reaction is conducted for 4-6 hours under the micro-negative pressure condition, and most of foul smell is eliminated; (2) adding hydrogen peroxide into the mixed solution treated in the step (1), and reacting at room temperature for 2.5-3.5 hours to completely deodorize; adjusting the pH (Potential of Hydrogen) to 8.0 to 9.0; (3) carrying out solid-liquid separation on the mixed solution treated in the step (2), recycling filter residues, and carrying out next-step reaction on filtrate; 4) adjusting the pH value of the filtrate treated in the step 3) to 2.8-3.3 by using dilute sulphuric acid, and adding ferrous sulfate / hydrogen peroxide into the filtrate for deep treatment; adjusting the pH (Potential of Hydrogen) to 8.0 to 9.0; and (5) carrying out solid-liquid separation on the mixed solution treated in the step (4), and recycling the filtrate after evaporative desalination and biochemical treatment.

Description

Technical Field

[0001] This invention belongs to the field of hazardous waste treatment technology, specifically relating to a multi-stage oxidation treatment method for petroleum refining waste alkali liquid. Background Technology

[0002] In petrochemical production processes, waste alkaline solutions containing large amounts of pollutants are generated from the absorption of sulfides using sodium hydroxide (potassium hydroxide) solutions. Because these solutions contain sulfides, thiols, sulfides, and other substances, they have a foul, unpleasant odor. In the "National Hazardous Waste List," waste alkaline solutions and alkali residues generated during petroleum refining are classified as HW35 category hazardous waste. These waste alkaline solutions possess corrosive and toxic properties, and if not properly treated, they can cause serious environmental and social harm.

[0003] Patent application CN 117550736 A discloses a method for treating waste alkaline solution from petroleum refining, comprising the following steps: 1) mixing sodium hydroxide solution with the waste alkaline solution via a storage tank; 2) adding the mixed solution to a reactor for oxidation; and 3) performing gas-liquid separation on the oxidized waste alkaline solution via a circulating cooling tower. However, this method may produce toxic byproducts, as it uses chlorate-containing oxidants (sodium hypochlorite, sodium chlorite, etc.) to oxidize sulfides and other substances, potentially generating toxic byproducts such as chlorinated organic compounds.

[0004] Currently, the main methods for treating waste alkaline solutions include wet air oxidation, photo-oxidation, and integrated treatment methods combining neutralization, oxidation, and biological processes. These methods convert sulfides into relatively stable sulfur, insoluble metal sulfides, or soluble sulfates. However, wet air oxidation requires high temperature and pressure, resulting in expensive engineering costs and hindering its further promotion. Photo-oxidation suffers from high reagent costs, high overall costs, and low light utilization rates, and is mainly in the laboratory research stage. Integrated treatment methods are effective for waste disposal, but they are difficult to implement due to supply chain integration issues. Therefore, a new disposal technology is needed to achieve the complete treatment of waste alkaline solutions. Summary of the Invention

[0005] The purpose of this invention is to provide a multi-stage oxidation treatment method for petroleum refining waste alkali liquid, so as to degrade the high concentration of COD and toxic and harmful pollutants in the waste alkali liquid, realize the harmless treatment and reuse of the waste alkali liquid, and avoid harm to the environment.

[0006] The objective of this invention can be achieved through the following technical solutions:

[0007] A multi-stage oxidation treatment method for waste alkaline liquor from petroleum refining includes the following steps:

[0008] 1) Add ZnS to the waste alkaline solution x@Fe3O4 / MIL-100(Fe) and a chlorate-containing oxidant solution reacted under slight negative pressure for 4-6 hours to eliminate most of the foul odor;

[0009] 2) Add hydrogen peroxide to the mixture after treatment in step 1), react at room temperature for 2.5-3.5 hours to completely deodorize; adjust the pH to 8.0-9.0;

[0010] 3) The mixture after step 2) is subjected to solid-liquid separation. The filter residue is reused, and the filtrate is used for the next reaction.

[0011] 4) Adjust the pH of the filtrate after treatment in step 3) to 2.8-3.3 using dilute sulfuric acid, and add ferrous sulfate / hydrogen peroxide for further treatment; adjust the pH to 8.0-9.0.

[0012] 5) The mixture after step 4) is subjected to solid-liquid separation, and the filtrate is reused after evaporation, desalination and biochemical treatment.

[0013] Furthermore, the ZnS x @Fe3O4 / MIL-100(Fe) is prepared by the following steps:

[0014] S1. Mix Zn(CH3COO)2 solution with thioacetamide solution, and stir at a constant temperature of 55-65℃ under N2 protection; add mercaptoacetic acid and continue stirring to obtain ZnS quantum dots;

[0015] S2. Using the co-precipitation method, FeCl3·6H2O solution and FeCl2·4H2O solution were mixed and the pH was adjusted to 11; citric acid was added, and the mixture was refluxed at 75-85℃ and magnetically separated and washed until neutral to obtain nano Fe3O4.

[0016] S3. Disperse nano-Fe3O4 in DMF, add FeCl3·6H2O and pyromellitic acid, and synthesize Fe3O4 / MIL-100(Fe) by microwave.

[0017] S4. ZnS quantum dots and Fe3O4 / MIL-100(Fe) were mixed in ethanol and dried under vacuum to obtain ZnS. x @Fe3O4 / MIL-100(Fe), 0<x<1.

[0018] Furthermore, the Zn:S molar ratio is 1:(1-1.4).

[0019] Furthermore, the amount of thioglycolic acid added is 0.1% to 0.5% of the total mass of the solution in S1.

[0020] Furthermore, the volume ratio of the FeCl3·6H2O solution to the FeCl2·4H2O solution is (1.8-2.3):1; the concentration of the FeCl3·6H2O solution is 0.4-0.6 mol / L, and the concentration of the FeCl2·4H2O solution is 0.2-0.3 mol / L.

[0021] Furthermore, the weight ratio of the nano-Fe3O4, DMF, FeCl3·6H2O and trimesic acid is 1:(40-60):(0.5-0.6):(0.25-0.35).

[0022] Furthermore, the weight ratio of the ZnS quantum dots, Fe3O4 / MIL-100(Fe) and ethanol is (0.15-0.25):(0.9-1.1):(40-65).

[0023] Furthermore, the waste alkaline solution has a pH of 12-14, total sulfides of 4000-5000 mg / L, and COD of 70,000-90,000 mg / L.

[0024] Furthermore, the ZnS x The amount of Fe3O4 / MIL-100(Fe) added is 0.6-1.2 g / L; the amount of the chlorate-containing oxidant added is 14-17 g / L.

[0025] Furthermore, the micro-negative pressure is -0.02 to -0.08 MPa.

[0026] Furthermore, in step 1), the chlorate-containing oxidant is one or more of sodium hypochlorite, sodium chlorite, and sodium chlorate.

[0027] Furthermore, the hydrogen peroxide concentration is 25% to 35%, and the amount of hydrogen peroxide added in step 2) is 2% to 5% of the solution volume.

[0028] Furthermore, the filter residue recycling step is as follows: the filter residue is regenerated by soaking it in a mixed solution of 0.1-0.2 mol / L NaOH and 5%-10% ethanol for 30-60 minutes, and then it can be recycled.

[0029] Furthermore, in step 4), the amount of ferrous sulfate added is 3% to 10% of the solution mass, and the amount of hydrogen peroxide added is 1% to 4% of the solution volume.

[0030] By controlling the reagents in the reaction system under micro-negative pressure conditions, the chemical substances that produce foul odors in the waste alkali solution are eliminated through a multi-stage reaction process, and then further treated by an advanced oxidation system to achieve safe treatment of the waste alkali solution.

[0031] Treatment principle: The primary treatment target is waste alkaline solution from petroleum refining (alkalinity: 2-5 mol / L, sulfur ion + mercaptans + thioether content: 0.2%–0.5%, COD content: 30000 mg / L–90000 mg / L). First, the reaction system is maintained under slight negative pressure to ensure no foul odors would affect personnel operations. A composite material, using the porous structure of MIL-100 (Fe), is used to target and adsorb malodorous substances such as mercaptans and thioethers. ZnS... x Fe3O4 forms a coordinate bond with S2- to enhance trapping. 3+ / Fe 2+ Cyclic catalytic directed oxidation of chlorates S 2- Using a chlorate-containing oxidant solution (sodium hypochlorite, sodium chlorite, sodium chlorate), sulfide ions, thiols, and thioethers in the waste alkaline solution are oxidized into sulfates, disulfides, sulfonic acids, etc. This step initially achieves the degradation of sulfides and thiols, eliminating most of the malodorous odor. Then, hydrogen peroxide is added, which can oxidize unreacted thiols, thioethers, and disulfides under alkaline conditions to generate corresponding sulfones and sulfoxides. Then, ferrous sulfate / hydrogen peroxide is added to form a Fenton oxidation system for deep treatment, oxidizing organic matter such as sulfonic acids into CO2 and H2O. Finally, sodium hydroxide is added to adjust the pH to 8.0. After solid-liquid separation, the filter residue is handed over to a qualified company for treatment, and the filtrate is recycled after evaporation, desalination, and biochemical treatment.

[0032] Main reaction mechanism:

[0033] NaClO + S 2- →NaSO4 + NaCl

[0034] NaClO + R-SH → R-SO4 + NaCl + H2O

[0035] NaClO + RSSR → R-SO4 + NaCl + H2O

[0036] H2O2+S 2- →NaSO4 + H2O

[0037] H₂O₂ + R⁻SH → RS(O)H + H₂O

[0038] H2O2 + RSS-R' → RS(O)-S(O)-R'

[0039] H2O2+R-SH→RSS-R'→RS(O)-S(O)-R'

[0040] H2O2 + Fe 2+ +R-SO3H→HOOC-R'-COOH→CO2+H2O

[0041] HOO-R-OOH + HO (high dose) → H2O + CO2

[0042] Fe 2+ +S 2- →FeS↓

[0043] The beneficial effects of this invention are:

[0044] (1) The ZnS used in this invention x In @Fe3O4 / MIL-100(Fe), the porous structure of MIL-100(Fe) can target and adsorb malodorous organic compounds such as thiols and thioethers. ZnS x Through S 2- The formation of coordination bonds enhances sulfide capture, while Fe3O4 contains Fe 3+ / Fe 2+ The cycle catalyzes the directional oxidation of chlorates containing S. 2- It is a sulfate. The three components work synergistically to improve the capture rate of malodorous substances, increase the oxidation rate of S2-, and significantly reduce the amount of subsequent oxidant used, thus solving the problem of incomplete malodor control in traditional oxidation methods.

[0045] (2) In this invention, Fe3O4 not only catalyzes the chlorate-containing reaction in the pre-oxidation stage, but also promotes the conversion of residual thiols and sulfides into odorless sulfones / sulfoxides in the hydrogen peroxide oxidation stage, while simultaneously replenishing Fe for subsequent Fenton oxidation. 2+ It synergistically generates more ·OH with ferrous sulfate, enhancing the mineralization of recalcitrant organic compounds such as sulfonic acid. This end-to-end synergistic process of "adsorption-catalysis-oxidation" significantly improves the removal rate of total sulfides and avoids the formation of chlorinated byproducts, solving the problem of high toxicity of byproducts in traditional oxidation methods.

[0046] (3) The micro-negative pressure conditions, multi-stage oxidation and high-efficiency adsorption synergy of composite materials adopted in this invention can control the odor concentration in the operating environment to below 50 ppm, ensuring operational safety; after solid-liquid separation, the filter residue is regenerated by NaOH-ethanol solution, which greatly reduces material costs. At the same time, the filtrate after terminal evaporation and desalination can be biochemically reused to achieve "treatment-resource utilization", reduce process costs, and achieve significant environmental and economic benefits. Attached Figure Description

[0047] The invention will now be further described with reference to the accompanying drawings.

[0048] Figure 1 This is a schematic flowchart of the multi-stage oxidation treatment method of the present invention. Detailed Implementation

[0049] The specific embodiments of the present invention will be described in detail below, but it should be understood that the scope of protection of the present invention is not limited to the specific embodiments.

[0050] Example 1

[0051] This embodiment provides a multi-stage oxidation treatment method for petroleum refining waste alkaline liquor, which is prepared through the following steps:

[0052] 1) Mix 200 mL of 0.1 mol / L Zn(CH3COO)2 solution with 200 mL of 0.12 mol / L thioacetamide (TAA) solution, and stir magnetically at 600 rpm for 2 hours under N2 protection at 60 °C; add 1.0 g of mercaptoacetic acid and continue stirring for 30 minutes to obtain ZnS quantum dots;

[0053] 2) Using the co-precipitation method, 300 mL of 0.5 mol / L FeCl3·6H2O solution was mixed with 150 mL of 0.25 mol / L FeCl2·4H2O solution, and the pH was adjusted to 11 with ammonia. 10 wt% citric acid was added, and the mixture was refluxed at 80 °C for 1 hour. After magnetic separation and washing until neutral, Fe3O4 nanomaterials were obtained.

[0054] 3) 1.0 g Fe3O4 was dispersed in 50 mL LDM, 0.55 g FeCl3·6H2O and 0.3 g trimesic acid were added, and the mixture was synthesized by microwave (120 °C, 300 W, 30 min) to obtain Fe3O4 / MIL-100(Fe);

[0055] 4) Mix 0.2 g of ZnS quantum dots with 1.0 g of Fe3O4 / MIL-100(Fe) in 50 mL of ethanol, and dry under vacuum at 60 °C for 12 hours to obtain ZnS. x @Fe3O4 / MIL-100(Fe), 0<x<1;

[0056] 5) Odor removal treatment: Add 0.8 g / L ZnS to the waste alkaline solution (pH 13, total sulfide 4500 mg / L, COD 80,000 mg / L). x @Fe3O4 / MIL-100(Fe) and 150mL / L 10% sodium hypochlorite solution were reacted at room temperature under slight negative pressure (-0.06MPa) for 5 hours until most of the foul odor was eliminated;

[0057] 6) Oxidation reaction: Add 30% hydrogen peroxide to the mixture after treatment in step 5), the amount added is 3% of the solution volume, react at room temperature for 3 hours, and after oxidation to sulfone and sulfoxide, the reaction system is completely deodorized; adjust the pH to 8.5 using dilute sulfuric acid;

[0058] 7) Solid-liquid separation: The mixture after step 6) is subjected to solid-liquid separation. The filter residue is reused. The reuse steps are as follows: the filter residue is regenerated by soaking it in a mixed solution of 0.1 mol / L NaOH and 5% ethanol for 30 minutes. The filtrate can then be recycled for the next reaction.

[0059] 8) Advanced treatment: Adjust the pH of the filtrate after treatment in step 7) to 3.0 using dilute sulfuric acid, and add ferrous sulfate / hydrogen peroxide for advanced treatment. The amount of ferrous sulfate added is 5% of the solution mass, and the amount of hydrogen peroxide added is 3% of the solution volume. Adjust the pH of the mixture to 8.5 using sodium hydroxide.

[0060] 9) Solid-liquid separation: The mixture after step 8) is subjected to solid-liquid separation. The filter residue is handed over to a qualified company for processing, and the filtrate is reused after evaporation, desalination and biochemical treatment.

[0061] The above steps are as follows Figure 1 As shown.

[0062] Example 2

[0063] Compared with Example 1, the difference in this embodiment is that the amount of hydrogen peroxide added is increased and the amount of ferrous sulfate added is decreased. The specific implementation steps of 5) to 9) are as follows:

[0064] 5) Odor removal treatment: Add 0.8 g / L ZnS to the waste alkaline solution (pH 13, total sulfide 4500 mg / L, COD 80,000 mg / L). x @Fe3O4 / MIL-100(Fe) and 150mL / L 10% sodium hypochlorite solution were reacted at room temperature under slight negative pressure (-0.06MPa) for 5 hours until most of the foul odor was eliminated;

[0065] 6) Oxidation reaction: Add 30% hydrogen peroxide to the mixture after treatment in step 5), the amount added is 5% of the solution volume, react at room temperature for 3 hours, and after oxidation to sulfone and sulfoxide, the reaction system is completely deodorized; adjust the pH to 9 using dilute sulfuric acid;

[0066] 7) Solid-liquid separation: The mixture after step 6) is subjected to solid-liquid separation. The filter residue is reused. The reuse steps are as follows: the filter residue is regenerated by soaking it in a mixed solution of 0.1 mol / L NaOH and 5% ethanol for 30 minutes. The filtrate can then be recycled for the next reaction.

[0067] 8) Advanced treatment: Adjust the pH of the filtrate after treatment in step 7) to 2.9 using dilute sulfuric acid, and add ferrous sulfate / hydrogen peroxide for advanced treatment. The amount of ferrous sulfate added is 3% of the solution mass, and the amount of hydrogen peroxide added is 5% of the solution volume. Adjust the pH of the mixture to 8.5 using sodium hydroxide.

[0068] 9) Solid-liquid separation: The mixture after step 8) is subjected to solid-liquid separation. The filter residue is handed over to a qualified company for processing, and the filtrate is reused after evaporation, desalination and biochemical treatment.

[0069] The remaining raw materials and preparation process are the same as in Example 1.

[0070] The above steps are as follows Figure 1 As shown.

[0071] Example 3

[0072] Compared with Example 1, the difference in this embodiment is that the amount of hydrogen peroxide added is reduced and the amount of ferrous sulfate added is increased. The specific implementation steps of 5) to 9) are as follows:

[0073] 5) Odor removal treatment: Add 0.8 g / L ZnS to the waste alkaline solution (pH 13, total sulfide 4500 mg / L, COD 80,000 mg / L). x @Fe3O4 / MIL-100(Fe) and 150mL / L 10% sodium hypochlorite solution were reacted at room temperature under slight negative pressure (-0.06MPa) for 5 hours until most of the foul odor was eliminated;

[0074] 6) Oxidation reaction: Add 30% hydrogen peroxide to the mixture after treatment in step 5), the amount added is 2% of the solution volume, react at room temperature for 3 hours, and after oxidation to sulfone and sulfoxide, the reaction system is completely deodorized; adjust the pH to 8.5 using dilute sulfuric acid;

[0075] 7) Solid-liquid separation: The mixture after step 6) is subjected to solid-liquid separation. The filter residue is reused. The reuse steps are as follows: the filter residue is regenerated by soaking it in a mixed solution of 0.1 mol / L NaOH and 5% ethanol for 30 minutes. The filtrate can then be recycled for the next reaction.

[0076] 8) Advanced treatment: Adjust the pH of the filtrate after treatment in step 7) to 3.1 using dilute sulfuric acid, and add ferrous sulfate / hydrogen peroxide for advanced treatment. The amount of ferrous sulfate added is 8% of the solution mass, and the amount of hydrogen peroxide added is 2% of the solution volume. Adjust the pH of the mixture to 8.2 using sodium hydroxide.

[0077] 9) Solid-liquid separation: The mixture after step 8) is subjected to solid-liquid separation. The filter residue is handed over to a qualified company for processing, and the filtrate is reused after evaporation, desalination and biochemical treatment.

[0078] The remaining raw materials and preparation process are the same as in Example 1.

[0079] The above steps are as follows Figure 1 As shown.

[0080] Example 4

[0081] The difference between this embodiment and Embodiment 1 is that the ZnS content is increased. x The addition amount of @Fe3O4 / MIL-100(Fe) is reduced, and the addition amount of chlorate-containing oxidant is decreased. The specific implementation steps for steps 5) to 9) are as follows:

[0082] 5) Odor removal treatment: Add 1.2 g / L ZnS to the waste alkaline solution (pH 13, total sulfide 4500 mg / L, COD 80,000 mg / L). x @Fe3O4 / MIL-100(Fe) and 140mL / L 10% sodium hypochlorite solution were reacted at room temperature under slight negative pressure (-0.05MPa) for 5 hours until most of the foul odor was eliminated;

[0083] 6) Oxidation reaction: Add 30% hydrogen peroxide to the mixture after treatment in step 5), the amount added is 3% of the solution volume, react at room temperature for 3 hours, and after oxidation to sulfone and sulfoxide, the reaction system is completely deodorized; adjust the pH to 8.5 using dilute sulfuric acid;

[0084] 7) Solid-liquid separation: The mixture after step 6) is subjected to solid-liquid separation. The filter residue is reused. The reuse steps are as follows: the filter residue is regenerated by soaking it in a mixed solution of 0.1 mol / L NaOH and 5% ethanol for 30 minutes. The filtrate can then be recycled for the next reaction.

[0085] 8) Advanced treatment: Adjust the pH of the filtrate after treatment in step 7) to 3.0 using dilute sulfuric acid, and add ferrous sulfate / hydrogen peroxide for advanced treatment. The amount of ferrous sulfate added is 5% of the solution mass, and the amount of hydrogen peroxide added is 3% of the solution volume. Adjust the pH of the mixture to 8.5 using sodium hydroxide.

[0086] 9) Solid-liquid separation: The mixture after step 8) is subjected to solid-liquid separation. The filter residue is handed over to a qualified company for processing, and the filtrate is reused after evaporation, desalination and biochemical treatment.

[0087] The remaining raw materials and preparation process are the same as in Example 1.

[0088] The above steps are as follows Figure 1 As shown.

[0089] Example 5

[0090] The difference between this embodiment and Embodiment 1 is that the ZnS content is reduced. x The addition amount of @Fe3O4 / MIL-100(Fe) increases the addition amount of chlorate-containing oxidant. The specific implementation steps for steps 5) to 9) are as follows:

[0091] 5) Odor removal treatment: Add 0.6 g / L ZnS to the waste alkaline solution (pH 13, total sulfide 4500 mg / L, COD 80,000 mg / L). x @Fe3O4 / MIL-100(Fe) and 165mL / L 10% sodium hypochlorite solution were reacted at room temperature under slight negative pressure (-0.08MPa) for 5 hours until most of the foul odor was eliminated;

[0092] 6) Oxidation reaction: Add 30% hydrogen peroxide to the mixture after treatment in step 5), the amount added is 3% of the solution volume, react at room temperature for 3 hours, and after oxidation to sulfone and sulfoxide, the reaction system is completely deodorized; adjust the pH to 8.5 using dilute sulfuric acid;

[0093] 7) Solid-liquid separation: The mixture after step 6) is subjected to solid-liquid separation. The filter residue is reused. The reuse steps are as follows: the filter residue is regenerated by soaking it in a mixed solution of 0.1 mol / L NaOH and 5% ethanol for 30 minutes. The filtrate can then be recycled for the next reaction.

[0094] 8) Advanced treatment: Adjust the pH of the filtrate after treatment in step 7) to 3.0 using dilute sulfuric acid, and add ferrous sulfate / hydrogen peroxide for advanced treatment. The amount of ferrous sulfate added is 5% of the solution mass, and the amount of hydrogen peroxide added is 3% of the solution volume. Adjust the pH of the mixture to 8.5 using sodium hydroxide.

[0095] 9) Solid-liquid separation: The mixture after step 8) is subjected to solid-liquid separation. The filter residue is handed over to a qualified company for processing, and the filtrate is reused after evaporation, desalination and biochemical treatment.

[0096] The remaining raw materials and preparation process are the same as in Example 1.

[0097] The above steps are as follows Figure 1 As shown.

[0098] Example 6

[0099] The difference between this embodiment and Embodiment 1 is that the ZnS is adjusted. x The specific implementation steps for the preparation of Fe3O4 / MIL-100(Fe), including the component dosages and steps 1) to 4), are as follows:

[0100] 1) Mix 200 mL of 0.1 mol / L Zn(CH3COO)2 solution with 200 mL of 0.14 mol / L thioacetamide (TAA) solution, and stir magnetically at 600 rpm for 2 hours under N2 protection; add 1.1 g of mercaptoacetic acid and continue stirring for 30 minutes to obtain ZnS quantum dots;

[0101] 2) Using the co-precipitation method, 300 mL of 0.5 mol / L FeCl3·6H2O solution was mixed with 150 mL of 0.25 mol / L FeCl2·4H2O solution, and the pH was adjusted to 11 with ammonia. 10 wt% citric acid was added, and the mixture was refluxed at 80 °C for 1 hour. After magnetic separation and washing until neutral, Fe3O4 nanomaterials were obtained.

[0102] 3) 1.1g Fe3O4 was dispersed in 50ml LDM, 0.5g FeCl3·6H2O and 0.25g trimellitic acid were added, and the mixture was synthesized by microwave (120℃, 300W, 30 minutes) to obtain Fe3O4 / MIL-100(Fe);

[0103] 4) Mix 0.25 g of ZnS quantum dots with 0.9 g of Fe3O4 / MIL-100(Fe) in 60 mL of ethanol, and dry under vacuum at 60 °C for 12 hours to obtain ZnS. x @Fe3O4 / MIL-100(Fe), 0<x<1;

[0104] The remaining raw materials and preparation process are the same as in Example 1.

[0105] The above steps are as follows Figure 1 As shown.

[0106] Example 7

[0107] The difference between this embodiment and Embodiment 1 is that the ZnS is adjusted. x The specific implementation steps for the preparation of Fe3O4 / MIL-100(Fe), including the component dosages and steps 1) to 4), are as follows:

[0108] 1) Mix 200 mL of 0.1 mol / L Zn(CH3COO)2 solution with 200 mL of 0.11 mol / L thioacetamide (TAA) solution, and stir magnetically at 600 rpm for 2 hours under N2 protection; add 0.95 g of mercaptoacetic acid and continue stirring for 30 minutes to obtain ZnS quantum dots;

[0109] 2) Using the co-precipitation method, 300 mL of 0.5 mol / L FeCl3·6H2O solution was mixed with 150 mL of 0.25 mol / L FeCl2·4H2O solution, and the pH was adjusted to 10.5 with ammonia. 10 wt% citric acid was added, and the mixture was refluxed at 80 °C for 1 hour. After magnetic separation and washing until neutral, Fe3O4 nanomaterials were obtained.

[0110] 3) 1.0 g Fe3O4 was dispersed in 55 mL LDM, 0.6 g FeCl3·6H2O and 0.35 g trimesic acid were added, and the mixture was synthesized by microwave (120 °C, 300 W, 30 min) to obtain Fe3O4 / MIL-100(Fe);

[0111] 4) Mix 0.15 g of ZnS quantum dots with 1.1 g of Fe3O4 / MIL-100(Fe) in 55 mL of ethanol, and dry under vacuum at 60 °C for 12 hours to obtain ZnS. x @Fe3O4 / MIL-100(Fe), 0<x<1;

[0112] The remaining raw materials and preparation process are the same as in Example 1.

[0113] The above steps are as follows Figure 1 As shown.

[0114] Example 8

[0115] The difference between this embodiment and Example 1 is that the type of chlorate-containing oxidant is replaced, and the specific implementation steps 5) to 9) are as follows:

[0116] 5) Odor removal treatment: Add 0.8 g / L ZnS to the waste alkaline solution (pH 12-14, total sulfide 4500 mg / L, COD 80,000 mg / L). x @Fe3O4 / MIL-100(Fe) and 150mL / L 10% sodium chlorite solution were reacted at room temperature under slight negative pressure (-0.07MPa) for 5 hours until most of the foul odor was eliminated;

[0117] 6) Oxidation reaction: Add 30% hydrogen peroxide to the mixture after treatment in step 5), the amount added is 3% of the solution volume, react at room temperature for 3 hours, and after oxidation to sulfone and sulfoxide, the reaction system is completely deodorized; adjust the pH to 8.5 using dilute sulfuric acid;

[0118] 7) Solid-liquid separation: The mixture after step 6) is subjected to solid-liquid separation. The filter residue is reused. The reuse steps are as follows: the filter residue is regenerated by soaking it in a mixed solution of 0.1 mol / L NaOH and 5% ethanol for 30 minutes. The filtrate can then be recycled for the next reaction.

[0119] 8) Advanced treatment: Adjust the pH of the filtrate after treatment in step 7) to 3.0 using dilute sulfuric acid, and add ferrous sulfate / hydrogen peroxide for advanced treatment. The amount of ferrous sulfate added is 5% of the solution mass, and the amount of hydrogen peroxide added is 3% of the solution volume. Adjust the pH of the mixture to 8.5 using sodium hydroxide.

[0120] 9) Solid-liquid separation: The mixture after step 8) is subjected to solid-liquid separation. The filter residue is handed over to a qualified company for processing, and the filtrate is reused after evaporation, desalination and biochemical treatment.

[0121] The remaining raw materials and preparation process are the same as in Example 1.

[0122] The above steps are as follows Figure 1 As shown.

[0123] Comparative Example 1

[0124] The difference between this comparative example and Example 1 is that it is not carried out in a slightly negative pressure environment. The specific implementation steps 5) to 9) are as follows:

[0125] 5) Odor removal treatment: Add 0.8 g / L ZnS to the waste alkaline solution (pH 13, total sulfide 4500 mg / L, COD 80,000 mg / L). x @Fe3O4 / MIL-100(Fe) and 150mL / L 10% sodium hypochlorite solution were reacted at room temperature for 5 hours until most of the foul odor was eliminated;

[0126] 6) Oxidation reaction: Add 30% hydrogen peroxide to the mixture after treatment in step 5), the amount added is 3% of the solution volume, react at room temperature for 3 hours, and after oxidation to sulfone and sulfoxide, the reaction system is completely deodorized; adjust the pH to 8.5 using dilute sulfuric acid;

[0127] 7) Solid-liquid separation: The mixture after step 6) is subjected to solid-liquid separation. The filter residue is reused. The reuse steps are as follows: the filter residue is regenerated by soaking it in a mixed solution of 0.1 mol / L NaOH and 5% ethanol for 30 minutes. The filtrate can then be recycled for the next reaction.

[0128] 8) Advanced treatment: Adjust the pH of the filtrate after treatment in step 7) to 3.0 using dilute sulfuric acid, and add ferrous sulfate / hydrogen peroxide for advanced treatment. The amount of ferrous sulfate added is 5% of the solution mass, and the amount of hydrogen peroxide added is 3% of the solution volume. Adjust the pH of the mixture to 8.5 using sodium hydroxide.

[0129] 9) Solid-liquid separation: The mixture after step 8) is subjected to solid-liquid separation. The filter residue is handed over to a qualified company for processing, and the filtrate is reused after evaporation, desalination and biochemical treatment.

[0130] The remaining raw materials and preparation process are the same as in Example 1.

[0131] The above steps are as follows Figure 1 As shown.

[0132] Comparative Example 2

[0133] The difference between this comparative example and Example 1 is that no chlorate-containing oxidant is added. The specific implementation steps 5) to 9) are as follows:

[0134] 5) Odor removal treatment: Add 0.8 g / L ZnS to the waste alkaline solution (pH 13, total sulfide 4500 mg / L, COD 80,000 mg / L). x@Fe3O4 / MIL-100(Fe) was reacted at room temperature under slight negative pressure (-0.06MPa) for 5 hours until most of the foul odor was eliminated;

[0135] 6) Oxidation reaction: Add 30% hydrogen peroxide to the mixture after treatment in step 5), the amount added is 3% of the solution volume, react at room temperature for 3 hours, and after oxidation to sulfone and sulfoxide, the reaction system is completely deodorized; adjust the pH to 8.5 using dilute sulfuric acid;

[0136] 7) Solid-liquid separation: The mixture after step 6) is subjected to solid-liquid separation. The filter residue is reused. The reuse steps are as follows: the filter residue is regenerated by soaking it in a mixed solution of 0.1 mol / L NaOH and 5% ethanol for 30 minutes. The filtrate can then be recycled for the next reaction.

[0137] 8) Advanced treatment: Adjust the pH of the filtrate after treatment in step 7) to 3.0 using dilute sulfuric acid, and add ferrous sulfate / hydrogen peroxide for advanced treatment. The amount of ferrous sulfate added is 5% of the solution mass, and the amount of hydrogen peroxide added is 3% of the solution volume. Adjust the pH of the mixture to 8.5 using sodium hydroxide.

[0138] 9) Solid-liquid separation: The mixture after step 8) is subjected to solid-liquid separation. The filter residue is handed over to a qualified company for processing, and the filtrate is reused after evaporation, desalination and biochemical treatment.

[0139] The remaining raw materials and preparation process are the same as in Example 1.

[0140] The above steps are as follows Figure 1 As shown.

[0141] Comparative Example 3

[0142] The difference between this comparative example and Example 1 is that ZnS is not added. x The specific implementation steps for @Fe3O4 / MIL-100(Fe), 5)~9) are as follows:

[0143] 5) Odor elimination treatment: Add 150 mL / L of 10% sodium hypochlorite solution to the waste alkaline solution (pH 13, total sulfide 4500 mg / L, COD 80,000 mg / L), and react at room temperature under slight negative pressure (-0.06 MPa) for 5 hours until most of the odor is eliminated.

[0144] 6) Oxidation reaction: Add 30% hydrogen peroxide to the mixture after treatment in step 5), the amount added is 3% of the solution volume, react at room temperature for 3 hours, and after oxidation to sulfone and sulfoxide, the reaction system is completely deodorized; adjust the pH to 8.5 using dilute sulfuric acid;

[0145] 7) Solid-liquid separation: The mixture after step 6) is subjected to solid-liquid separation. The filter residue is reused. The reuse steps are as follows: the filter residue is regenerated by soaking it in a mixed solution of 0.1 mol / L NaOH and 5% ethanol for 30 minutes. The filtrate can then be recycled for the next reaction.

[0146] 8) Advanced treatment: Adjust the pH of the filtrate after treatment in step 7) to 3.0 using dilute sulfuric acid, and add ferrous sulfate / hydrogen peroxide for advanced treatment. The amount of ferrous sulfate added is 5% of the solution mass, and the amount of hydrogen peroxide added is 3% of the solution volume. Adjust the pH of the mixture to 8.5 using sodium hydroxide.

[0147] 9) Solid-liquid separation: The mixture after step 8) is subjected to solid-liquid separation. The filter residue is handed over to a qualified company for processing, and the filtrate is reused after evaporation, desalination and biochemical treatment.

[0148] The remaining raw materials and preparation process are the same as in Example 1.

[0149] The above steps are as follows Figure 1 As shown.

[0150] Comparative Example 4

[0151] The difference between this comparative example and Example 1 is that ZnS is not added. x The specific implementation steps are as follows:

[0152] 1) Using the co-precipitation method, 300 mL of 0.5 mol / L FeCl3·6H2O solution was mixed with 150 mL of 0.25 mol / L FeCl2·4H2O solution, and the pH was adjusted to 11 with ammonia water; 10 wt% citric acid was added, and the mixture was refluxed at 80 °C for 1 hour. After magnetic separation and washing until neutral, Fe3O4 nanomaterials were obtained.

[0153] 2) 1.0 g Fe3O4 was dispersed in 50 mL LDM, 0.55 g FeCl3·6H2O and 0.3 g trimesic acid were added, and the mixture was synthesized by microwave (120 °C, 300 W, 30 min) to obtain Fe3O4 / MIL-100(Fe);

[0154] 3) Odor elimination treatment: Add 0.8 g / L Fe3O4 / MIL-100 (Fe) and 150 mL / L 10% sodium hypochlorite solution to the waste alkaline solution (pH 13, total sulfide 4500 mg / L, COD 80,000 mg / L), and react at room temperature under slight negative pressure (-0.06 MPa) for 5 hours until most of the odor is eliminated;

[0155] 4) Oxidation reaction: Add 30% hydrogen peroxide to the mixture after treatment in step 5), the amount added is 3% of the solution volume, react at room temperature for 3 hours, and after oxidation to sulfone and sulfoxide, the reaction system is completely deodorized; adjust the pH to 8.5 using dilute sulfuric acid;

[0156] 5) Solid-liquid separation: The mixture after step 6) is subjected to solid-liquid separation. The filter residue is reused. The reuse steps are as follows: the filter residue is regenerated by soaking it in a mixed solution of 0.1 mol / L NaOH and 5% ethanol for 30 minutes. The filtrate can then be recycled for the next reaction.

[0157] 6) Advanced treatment: Adjust the pH of the filtrate after treatment in step 7) to 3.0 using dilute sulfuric acid, and add ferrous sulfate / hydrogen peroxide for advanced treatment. The amount of ferrous sulfate added is 5% of the solution mass, and the amount of hydrogen peroxide added is 3% of the solution volume. Adjust the pH of the mixture to 8.5 using sodium hydroxide.

[0158] 7) Solid-liquid separation: The mixture after step 8) is subjected to solid-liquid separation. The filter residue is handed over to a qualified company for processing, and the filtrate is reused after evaporation, desalination and biochemical treatment.

[0159] The remaining raw materials and preparation process are the same as in Example 1.

[0160] The above steps are as follows Figure 1 As shown.

[0161] Performance testing

[0162] The petroleum refining waste alkali liquor treated in Examples 1-8 and Comparative Examples 1-4 was tested:

[0163] 1. Odor Pollutant Control: The "Odor Pollutant Emission Standard" (GB 14554-1993) is used to detect the concentration of odorous substances (dimensionless) and hydrogen sulfide (H2S).

[0164] 2. Wastewater pollutant discharge: "Emission Standard of Pollutants from Petrochemical Industry" (GB 31571-2015), with tests for indicators such as COD and total sulfides.

[0165] 3. Material regeneration performance: Refer to the "Evaluation Method for Performance of Water Treatment Agents" (GB / T 23957-2009) to evaluate the activity retention rate of the composite material after recycling.

[0166] The results are shown in Table 1:

[0167] Table 1

[0168]

[0169] As shown in Table 1, the odor concentrations in Examples 1-8 were significantly lower than those in Comparative Examples 1, 2, 3, and 4. This effect stems from the synergistic effect of the composite material and the process: ZnS x In @Fe3O4 / MIL-100(Fe), the porous structure of MIL-100(Fe) targets and adsorbs malodorous organic compounds such as thiols and thioethers. ZnS x Through S 2- The formation of coordination bonds enhances sulfide capture, and the combination of the two increases the "enrichment-oxidation" efficiency of odorous substances by more than 40%; Fe3O4's Fe 3+ / Fe 2+ The cycle catalyzes the targeted oxidation of odorous substances containing chlorate, preventing their desorption and diffusion.

[0170] Regarding sulfide removal, the residual sulfide levels in Examples 1-8 were significantly lower than those in Comparative Examples 3 and 4. This is due to ZnS x Through Zn 2+ With S 2- Strong coordination will free S 2- The capture of S in a coordinated state provides a high concentration of reaction sites for Fe3O4-catalyzed chlorate oxidation, allowing S to... 2- The oxidation rate increased from 89.9% in Comparative Example 4 to 99.98% in Example 1; the three-dimensional porous structure of MIL-100(Fe) has a high adsorption capacity for thiols and thioethers, and the pore confinement effect increases the contact frequency between them and the oxidant, further improving the oxidation rate.

[0171] Regarding COD degradation, the COD residues in Examples 1-8 were significantly lower than those in Comparative Examples 3 and 2, with COD removal rates ≥99.8%. This is attributed to the full-process catalytic effect of Fe3O4: in the pre-oxidation stage, Fe3O4 catalyzes the formation of chlorate to ClO·, which oxidizes readily degradable sulfides; in the hydrogen peroxide oxidation stage, Fe3O4 catalyzes the formation of readily degradable sulfides. 3+ / Fe 2+ Cycle promotes ·OH generation by oxidizing residual thiols as sulfones, and the Fenton stage supplements Fe. 2+ In synergistic effect with ferrous sulfate, the concentration of ·OH is increased, which enhances the mineralization of recalcitrant organic matter such as sulfonic acid. In contrast, Comparative Example 2 suffered from incomplete COD degradation due to the lack of chlorate pre-oxidation.

[0172] Regarding material cycling activity, the composite materials of Examples 1-8 showed significantly higher activity after 5 cycles compared to Comparative Example 4 and Comparative Example 1. This is due to the ZnS... x The protective effect of MIL-100(Fe): ZnS x The coating layer reduces the dissolution of Fe3O4 in a strongly alkaline environment, and the organic framework of MIL-100(Fe) provides physical support, reducing leaching. Comparative Example 4, lacking ZnS... xFe3O4 is easily corroded by sulfides, and its cycling activity drops sharply, highlighting the role of component synergy in improving the stability of the material.

[0173] The above-disclosed embodiments are merely a few specific examples of the present invention. However, the embodiments of the present invention are not limited thereto, and any variations that can be conceived by those skilled in the art should fall within the protection scope of the present invention.

Claims

1. A multi-stage oxidation treatment method for petroleum refining waste alkaline liquor, characterized in that, Includes the following steps: 1) Add ZnS to the waste alkaline solution x @Fe3O4 / MIL-100(Fe) and a chlorate-containing oxidant solution were reacted under slight negative pressure for 4-6 hours; 2) Add hydrogen peroxide to the mixture after treatment in step 1), react at room temperature for 2.5-3.5 hours, and adjust the pH to 8.0-9.0; 3) The mixture after step 2) is subjected to solid-liquid separation. The filter residue is reused, and the filtrate is used for the next reaction. 4) Adjust the pH of the filtrate after treatment in step 3) to 2.8-3.3, add ferrous sulfate / hydrogen peroxide for further treatment; adjust the pH to 8.0-9.

0. 5) The mixture after step 4) is subjected to solid-liquid separation, and the filtrate is reused after evaporation, desalination and biochemical treatment.

2. The multi-stage oxidation treatment method for petroleum refining waste alkali liquor according to claim 1, characterized in that, The ZnS x @Fe3O4 / MIL-100(Fe) is prepared by the following steps: S1. Mix Zn(CH3COO)2 solution with thioacetamide solution, and stir at a constant temperature of 55-65℃ under N2 protection; add mercaptoacetic acid and continue stirring to obtain ZnS quantum dots; S2. Using the co-precipitation method, FeCl3·6H2O solution and FeCl2·4H2O solution were mixed and the pH was adjusted to 11; citric acid was added, and the mixture was refluxed at 75-85℃ and magnetically separated and washed until neutral to obtain nano Fe3O4. S3. Disperse nano-Fe3O4 in DMF, add FeCl3·6H2O and pyromellitic acid, and synthesize Fe3O4 / MIL-100(Fe) by microwave. S4. ZnS quantum dots and Fe3O4 / MIL-100(Fe) were mixed in ethanol and dried under vacuum to obtain ZnS. x @Fe3O4 / MIL-100(Fe), 0<x<1.

3. The multi-stage oxidation treatment method for petroleum refining waste alkali liquor according to claim 2, characterized in that, The Zn:S molar ratio is 1:(1-1.4); the amount of thioglycolic acid added is 0.1% to 0.5% of the total mass of the solution in S1.

4. The multi-stage oxidation treatment method for petroleum refining waste alkali liquor according to claim 2, characterized in that, The volume ratio of the FeCl3·6H2O solution to the FeCl2·4H2O solution is (1.8-2.3):1; the concentration of the FeCl3·6H2O solution is 0.4-0.6 mol / L, and the concentration of the FeCl2·4H2O solution is 0.2-0.3 mol / L.

5. The multi-stage oxidation treatment method for petroleum refining waste alkaline liquor according to claim 2, characterized in that, The weight ratio of nano-Fe3O4, DMF, FeCl3·6H2O and trimesic acid is 1:(40-60):(0.5-0.6):(0.25-0.35); the weight ratio of ZnS quantum dots, Fe3O4 / MIL-100(Fe) and ethanol is (0.15-0.25):(0.9-1.1):(40-65).

6. The multi-stage oxidation treatment method for petroleum refining waste alkali liquor according to claim 1, characterized in that, The waste alkaline solution has a pH of 12-14, total sulfides of 4000-5000 mg / L, and COD of 70,000-90,000 mg / L.

7. The multi-stage oxidation treatment method for petroleum refining waste alkali liquor according to claim 1, characterized in that, The ZnS x The amount of Fe3O4 / MIL-100(Fe) added is 0.6-1.2 g / L; the amount of the chlorate-containing oxidant added is 14-17 g / L.

8. The multi-stage oxidation treatment method for petroleum refining waste alkali liquor according to claim 1, characterized in that, The micro-negative pressure is -0.02 to -0.08 MPa.

9. The multi-stage oxidation treatment method for petroleum refining waste alkali liquor according to claim 1, characterized in that, In step 1), the chlorate oxidant is one or a combination of sodium hypochlorite, sodium chlorite, and sodium chlorate; the hydrogen peroxide concentration is 25%–35%; in step 2), the amount of hydrogen peroxide added is 2%–5% of the solution volume; in step 4), the amount of ferrous sulfate added is 3%–10% of the solution mass, and the amount of hydrogen peroxide added is 1%–4% of the solution volume.

10. A multi-stage oxidation treatment method for petroleum refining waste alkali liquor according to claim 1, characterized in that, The filter residue recycling process involves soaking the filter residue in a mixed solution of 0.1-0.2 mol / L NaOH and 5%-10% ethanol for 30-60 minutes for regeneration, after which it can be recycled.

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