A method for treating polyphenyl ether synthesis process wastewater and application

Abstract

The present application belongs to the technical field of wastewater treatment, and particularly relates to a method for treating wastewater from a polyphenyl ether synthesis process and application. The method for treating wastewater from the polyphenyl ether synthesis process comprises the following steps: adding an aromatic solvent to wastewater from the polyphenyl ether synthesis process to perform a first extraction; then adding sodium persulfate to perform a first degradation reaction; adding the aromatic solvent again to perform a second extraction; then adding sodium persulfate to perform a second degradation reaction to obtain wastewater after the second degradation reaction; adjusting the pH of the wastewater after the second degradation reaction to neutral or alkaline, filtering, and completing the wastewater treatment. The present application greatly reduces the COD of the wastewater by re-extracting the oxidation intermediate product, can reduce the COD of the wastewater from the polyphenyl ether synthesis process to below 500 mg / L, and even to 206 mg / L, reduces the wastewater COD by 98.9%, and has the advantages of simple operation, low energy consumption, and green environmental protection.

Description

Technical Field

[0001] This invention belongs to the field of wastewater treatment technology, and specifically relates to a method and application for treating wastewater from the polyphenylene ether synthesis process. Background Technology

[0002] Polyphenylene ether (PPE) possesses excellent heat resistance and dielectric properties, making it one of the ideal resin materials for high-frequency, high-speed copper-clad laminates (CCLs). However, PPE with conventional molecular weights has high melt viscosity and poor flowability, making it difficult to use in CCL manufacturing. Therefore, the industry generally uses difunctional low molecular weight PPE as the resin raw material for high-frequency, high-speed CCLs.

[0003] A typical method for preparing bifunctional low molecular weight polyphenylene ethers includes: oxidative copolymerization of tetramethylbisphenol A and 2,6-dimethylphenol under the catalytic conditions of a copper-amine complex; sequential addition of a chelating agent to chelate and extract copper ions after the reaction; addition of an alkaline solution to extract residual phenolic monomers; and washing and purification with deionized water. In actual production, approximately 400 kg of wastewater is generated for every ton of product produced. Furthermore, tetramethylbisphenol A has relatively low activity in this oxidative copolymerization reaction, generally requiring an increased amount of the copper-amine complex catalyst. Therefore, this type of wastewater contains higher concentrations of sodium phenolate, organic amines, and copper ion chelates, exhibiting a high chemical oxygen demand (COD), necessitating pretreatment before discharge into a wastewater treatment plant.

[0004] Due to the complex composition of such industrial wastewater, conventional methods such as Fenton oxidation, distillation, and biodegradation are insufficient for its direct and effective treatment. Currently, a method for treating polyphenylene ether (PPE) process wastewater has been disclosed, involving sequential alkali treatment, aeration, and distillation to thoroughly separate difficult-to-treat phenolic substances, amine-containing substances, and low-molecular-weight PPE, thus ensuring the wastewater meets standards. However, this method utilizes distillation with a reflux ratio of 2-3, resulting in high energy consumption. Furthermore, this method cannot effectively recover copper ions. Chelated copper ions exhibit high stability and typically require the use of sodium sulfide or sodium hydrosulfide for precipitation, which inevitably introduces sulfide ion contaminants.

[0005] Therefore, it is of great significance to provide a method for treating wastewater from polyphenylene ether synthesis processes that is energy-efficient, can effectively reduce COD in wastewater, and is environmentally friendly. Summary of the Invention

[0006] The present invention aims to solve one or more technical problems existing in the prior art, and at least provide a beneficial option or create conditions. Specifically, the present invention provides a method for treating wastewater from the polyphenylene ether synthesis process, which has low energy consumption, can effectively reduce the COD of the wastewater, and is environmentally friendly.

[0007] The inventive concept of this invention is as follows: The method for treating wastewater from the polyphenylene ether (PPE) synthesis process is as follows: An aromatic solvent is added to the PPE synthesis wastewater for a first extraction; then sodium persulfate is added for a first degradation reaction; an aromatic solvent is added again for a second extraction; then sodium persulfate is added again for a second degradation reaction, yielding wastewater after the second degradation reaction; the pH of the wastewater after the second degradation reaction is adjusted to neutral or alkaline, and then filtered to complete the treatment of the PPE synthesis wastewater. This invention sequentially performs a first extraction, a first oxidative degradation, a second extraction, and a second oxidative degradation, finally adjusting the pH to precipitate copper ions. This method is simple to operate, has low energy consumption, and significantly reduces the COD of the wastewater by further extracting the oxidative intermediates. Simultaneously, by oxidizing and degrading the copper ion ligands, the use of sulfides and hydrosulfides is avoided during the recovery of copper ions, thus preventing the introduction of sulfur ion pollutants, making it environmentally friendly. The treatment method of this invention can reduce the COD of PPE synthesis wastewater to below 500 mg / L.

[0008] Therefore, the first aspect of the present invention provides a method for treating wastewater from the polyphenylene ether synthesis process.

[0009] Specifically, the method for treating the wastewater from the polyphenylene ether synthesis process includes the following steps:

[0010] (1) Add an aromatic solvent to the wastewater from the polyphenylene ether synthesis process for the first extraction; then add sodium persulfate for the first degradation reaction; then add an aromatic solvent for the second extraction; then add sodium persulfate for the second degradation reaction to obtain the wastewater after the second degradation reaction.

[0011] (2) Adjust the pH of the wastewater obtained in step (1) after the second degradation reaction to neutral or alkaline, filter it, and complete the treatment of wastewater from the polyphenylene ether synthesis process.

[0012] Preferably, the wastewater from the polyphenylene ether synthesis process includes a complex of triacetate and copper ions, bromide ions, and tertiary amine compounds.

[0013] Preferably, the tertiary amine compound includes N,N-dimethylbutylamine.

[0014] Preferably, the pH of the wastewater from the polyphenylene ether synthesis process is 10-13.

[0015] Preferably, the COD of the wastewater from the polyphenylene ether synthesis process is 10,000-20,000 mg / L.

[0016] Preferably, the aromatic solvent includes at least one of toluene and xylene; more preferably, the aromatic solvent is toluene.

[0017] Preferably, in step (1), during the first extraction, the volume ratio of the aromatic solvent to the polyphenylene ether synthesis process wastewater is (0.1-0.5):1; more preferably, in step (1), during the first extraction, the volume ratio of the aromatic solvent to the polyphenylene ether synthesis process wastewater is (0.2-0.4):1.

[0018] Preferably, in step (1), the first extraction method is as follows: after adding an aromatic solvent, stir for 5-30 minutes, let stand to separate the phases, remove the light phase, and obtain the heavy phase, which is the wastewater after the first extraction.

[0019] Preferably, in step (1), during the first degradation reaction, the ratio of the concentration of sodium persulfate to the COD of the polyphenylene ether synthesis process wastewater is (0.8-1.2):1; more preferably, in step (1), during the first degradation reaction, the ratio of the concentration of sodium persulfate to the COD of the polyphenylene ether synthesis process wastewater is (0.9-1.1):1.

[0020] Preferably, the reaction temperature of the first degradation reaction is 5-40℃, and the reaction time of the first degradation reaction is 2-6h; more preferably, the reaction temperature of the first degradation reaction is 15-30℃, and the reaction time of the first degradation reaction is 3-5h.

[0021] Preferably, stirring is performed during the first degradation reaction.

[0022] Specifically, in the first degradation reaction, the amount of sodium persulfate added and the stirring time are related to the effect of the second extraction. By further controlling the amount of sodium persulfate added and the stirring time, it is beneficial to improve the effect of the second extraction.

[0023] Preferably, in step (1), during the second extraction, the volume ratio of the aromatic solvent to the polyphenylene ether synthesis process wastewater is (0.1-0.3):1; more preferably, in step (1), during the second extraction, the volume ratio of the aromatic solvent to the polyphenylene ether synthesis process wastewater is (0.15-0.25):1.

[0024] Preferably, in step (1), the second extraction method is as follows: after adding an aromatic solvent, stir for 5-30 minutes, let stand to separate the phases, remove the light phase, and obtain the heavy phase, which is the wastewater after the second extraction.

[0025] Preferably, in step (1), during the second degradation reaction, the ratio of the concentration of sodium persulfate to the COD of the polyphenylene ether synthesis process wastewater is (2-4):1; more preferably, in step (1), during the second degradation reaction, the ratio of the concentration of sodium persulfate to the COD of the polyphenylene ether synthesis process wastewater is (2.5-3.5):1.

[0026] Preferably, the reaction temperature of the second degradation reaction is 5-40℃, and the reaction time of the second degradation reaction is 18-30h; more preferably, the reaction temperature of the second degradation reaction is 15-30℃, and the reaction time of the second degradation reaction is 20-28h.

[0027] Preferably, during the second degradation reaction, the sodium persulfate is first stirred to dissolve, and then allowed to stand for the reaction.

[0028] Specifically, in the second degradation reaction, the amount of sodium persulfate added and the stirring time affect the precipitation effect of copper ions and the final COD of the wastewater. By further controlling the amount of sodium persulfate added and the stirring time, it is beneficial to improve the wastewater treatment effect.

[0029] Preferably, in step (2), the pH of the wastewater after the second degradation reaction obtained in step (1) is adjusted to neutral or alkaline by adding alkali.

[0030] Preferably, the alkali includes sodium hydroxide.

[0031] Preferably, in step (2), the pH is 7-9.

[0032] Specifically, when a large amount of alkali is added, it can be prepared into a solution in advance, and the addition rate can be controlled to avoid the liquid boiling caused by a large amount of neutralization heat and solubility heat.

[0033] Preferably, in step (2), after the wastewater from the polyphenylene ether synthesis process is treated, the COD of the wastewater is 200-500 mg / L; more preferably, in step (2), after the wastewater from the polyphenylene ether synthesis process is treated, the COD of the wastewater is 200-300 mg / L.

[0034] The second aspect of the present invention provides an application of the method for treating wastewater from the polyphenylene ether synthesis process described in the first aspect of the present invention in the field of wastewater treatment.

[0035] Compared with the prior art, the beneficial effects of the technical solution provided by the present invention are as follows:

[0036] (1) This invention first uses an aromatic solvent for initial extraction, then adds sodium persulfate for initial oxidative degradation. The product from the first oxidative degradation is then extracted a second time using an aromatic solvent, followed by a second oxidative degradation using sodium persulfate. Finally, the pH is adjusted to precipitate copper ions. This method is simple to operate and has low energy consumption. By extracting the intermediate oxidation product again, the COD of the wastewater is significantly reduced. Furthermore, by oxidizing and degrading the copper ion ligands, the use of sulfides and hydrosulfides is avoided during the copper ion recovery process, thus preventing the introduction of sulfur ion pollutants, making it environmentally friendly. The treatment method of this invention can reduce the COD of wastewater from the polyphenylene ether synthesis process to below 500 mg / L, and even as low as 206 mg / L, representing a 98.9% reduction in COD.

[0037] (2) In the first degradation reaction of the present invention, by adding a specific amount of sodium persulfate and controlling the time of the first degradation reaction, it is beneficial to improve the effect of the second extraction, thereby achieving the goal of significantly reducing COD after wastewater treatment. Detailed Implementation

[0038] To enable those skilled in the art to more clearly understand the technical solutions described in this invention, the following embodiments are provided for illustration. It should be noted that the following embodiments do not constitute a limitation on the scope of protection claimed by this invention.

[0039] Unless otherwise specified, the raw materials, reagents or devices used in the following examples are available from conventional commercial sources or can be obtained by existing known methods.

[0040] The polyphenylene ether synthesis process wastewater used in the embodiments and comparative examples of this invention was obtained by the following synthesis method, specifically including the following steps:

[0041] (1) Add 250 kg of 2,6-dimethylphenol, 50 kg of tetramethylbisphenol A, and 1000 kg of toluene to a reaction vessel. Stir until all monomers are dissolved. Then add 3.8 kg of di-n-butylamine, 11.3 kg of N,N-dimethylbutylamine, and 2.2 kg of 25 wt% copper bromide solution. Mix thoroughly and then introduce oxygen (15 Nm³). 3 The reaction was carried out at 40℃ for 200 min; after the reaction was completed, 37.5 kg of 5% sodium triamcinolone acetonide aqueous solution was added, and the mixture was stirred at 70℃ for 60 min. After the reaction was completed, the liquid was centrifuged to obtain a light phase polyphenylene ether solution and a heavy phase chelated copper ion wastewater W1.

[0042] (2) Add 10 kg of 5% sodium hydroxide solution to the light phase polyphenylene ether solution obtained in step (1), stir and react at 70°C for 60 min, and then centrifuge to obtain light phase polyphenylene ether solution and alkaline washing wastewater W2.

[0043] (3) Add 10 kg of deionized water to the light phase polyphenylene ether solution obtained in step (2), stir and react at 70°C for 60 min, and then centrifuge to obtain the light phase polyphenylene ether solution and water washing wastewater W3.

[0044] The above-mentioned heavy phase chelated copper ion wastewater W1, alkaline washing wastewater W2, and water washing wastewater W3 constitute the polyphenylene ether synthesis process wastewater. The wastewater has a pH of 11, a COD of 18500 mg / L, and is dark green in color.

[0045] Example 1

[0046] A method for treating wastewater from polyphenylene ether synthesis process includes the following steps:

[0047] (1) Add 300 mL of toluene to 1000 mL of polyphenylene ether synthesis process wastewater, stir for 10 min, let stand to separate phases, remove the light phase, and obtain the heavy phase, which is the wastewater after the first extraction.

[0048] (2) Add 18.5g of sodium persulfate to the wastewater after the first extraction obtained in step (1), stir at 25°C for 4h to carry out the first degradation reaction, and obtain the wastewater after the first degradation reaction.

[0049] (3) Add 200 mL of toluene to the wastewater after the first degradation reaction obtained in step (2), stir for 10 min, let stand to separate the phases, remove the light phase, and obtain the heavy phase, which is the wastewater after the second extraction.

[0050] (4) Add 55.5g of sodium persulfate to the wastewater after the second extraction obtained in step (3), stir to dissolve, let stand at 25°C for 24h, and carry out the second degradation reaction to obtain the wastewater after the second degradation reaction.

[0051] (5) Add a 30% sodium hydroxide solution to the wastewater after the second degradation reaction obtained in step (4), adjust the pH to 7.5, stir, so that copper ions precipitate, filter, and obtain a black solid and the treated wastewater.

[0052] Example 2

[0053] A method for treating wastewater from polyphenylene ether synthesis process includes the following steps:

[0054] (1) Add 200 mL of toluene to 1000 mL of polyphenylene ether synthesis process wastewater, stir for 10 min, let stand to separate phases, remove the light phase, and obtain the heavy phase, which is the wastewater after the first extraction.

[0055] (2) Add 20.3g of sodium persulfate to the wastewater after the first extraction obtained in step (1), stir at 25°C for 4h to carry out the first degradation reaction, and obtain the wastewater after the first degradation reaction;

[0056] (3) Add 250 mL of toluene to the wastewater after the first degradation reaction obtained in step (2), stir for 10 min, let stand to separate the phases, remove the light phase, and obtain the heavy phase, which is the wastewater after the second extraction.

[0057] (4) Add 59.2g of sodium persulfate to the wastewater after the second extraction obtained in step (3), stir to dissolve, let stand at 25°C for 28h, carry out the second degradation reaction, and obtain the wastewater after the second degradation reaction;

[0058] (5) Add a 30% sodium hydroxide solution to the wastewater after the second degradation reaction obtained in step (4), adjust the pH to 8, stir, so that copper ions precipitate, filter, and obtain a black solid and the treated wastewater.

[0059] Example 3

[0060] A method for treating wastewater from polyphenylene ether synthesis process includes the following steps:

[0061] (1) Add 300 mL of toluene to 1000 mL of polyphenylene ether synthesis process wastewater, stir for 15 min, let stand to separate phases, remove the light phase, and obtain the heavy phase, which is the wastewater after the first extraction.

[0062] (2) Add 18.5g of sodium persulfate to the wastewater after the first extraction obtained in step (1), stir at 15°C for 6h to carry out the first degradation reaction, and obtain the wastewater after the first degradation reaction.

[0063] (3) Add 200 mL of toluene to the wastewater after the first degradation reaction obtained in step (2), stir for 15 min, let stand to separate phases, remove the light phase, and obtain the heavy phase, which is the wastewater after the second extraction.

[0064] (4) Add 55.5g of sodium persulfate to the wastewater after the second extraction obtained in step (3), stir to dissolve, let stand at 15°C for 24h, and carry out the second degradation reaction to obtain the wastewater after the second degradation reaction.

[0065] (5) Add a 30% sodium hydroxide solution to the wastewater after the second degradation reaction obtained in step (4), adjust the pH to 9, stir, so that copper ions precipitate, filter, and obtain a black solid and the treated wastewater.

[0066] Example 4

[0067] A method for treating wastewater from polyphenylene ether synthesis process includes the following steps:

[0068] (1) Add 250 mL of toluene to 1000 mL of polyphenylene ether synthesis process wastewater, stir for 10 min, let stand to separate phases, remove the light phase, and obtain the heavy phase, which is the wastewater after the first extraction.

[0069] (2) Add 14.8g of sodium persulfate to the wastewater after the first extraction obtained in step (1), stir at 30°C for 4h to carry out the first degradation reaction, and obtain the wastewater after the first degradation reaction.

[0070] (3) Add 200 mL of toluene to the wastewater after the first degradation reaction obtained in step (2), stir for 10 min, let stand to separate the phases, remove the light phase, and obtain the heavy phase, which is the wastewater after the second extraction.

[0071] (4) Add 64.7g of sodium persulfate to the wastewater after the second extraction obtained in step (3), stir to dissolve, let stand at 30°C for 20h, and carry out the second degradation reaction to obtain the wastewater after the second degradation reaction.

[0072] (5) Add a 30% sodium hydroxide solution to the wastewater after the second degradation reaction obtained in step (4), adjust the pH to 7, stir, so that copper ions precipitate, filter, and obtain a black solid and the treated wastewater.

[0073] When treating wastewater from the polyphenylene ether synthesis process in Examples 1-4 of this invention, obvious experimental phenomena were observed. In Example 1, after adding sodium persulfate and stirring for 4 hours in step (2) for the first degradation reaction, the wastewater changed from dark green to blue. After adding sodium persulfate and letting it stand for 24 hours in step (4) for the second degradation reaction, the wastewater changed from blue to bright green. After adding sodium hydroxide solution in step (5) to adjust the pH to 7.5, the wastewater released a large amount of heat, the temperature rose sharply, and black solids were gradually generated. The filtered wastewater was colorless and transparent.

[0074] Comparative Example 1

[0075] The only difference between Comparative Example 1 and Example 1 is that Comparative Example 1 was subjected to two extractions, followed by a first degradation and a second degradation. Otherwise, it was the same as Example 1.

[0076] Specifically, the treatment method for the polyphenylene ether synthesis process wastewater in Comparative Example 1 includes the following steps:

[0077] (1) Add 300 mL of toluene to 1000 mL of polyphenylene ether synthesis process wastewater, stir for 10 min, let stand to separate phases, remove the light phase, and obtain the heavy phase, which is the wastewater after the first extraction.

[0078] (2) Add 200 mL of toluene to the wastewater after the first extraction obtained in step (1), stir for 10 min, let stand to separate the phases, remove the light phase, and obtain the heavy phase, which is the wastewater after the second extraction.

[0079] (3) Add 18.50g of sodium persulfate to the wastewater after the second extraction obtained in step (2), stir at 25°C for 4h to carry out the first degradation reaction, and obtain the wastewater after the first degradation reaction.

[0080] (4) Add 55.50g of sodium persulfate to the wastewater after the first degradation reaction obtained in step (3), stir to dissolve, let stand at 25°C for 24h, and carry out the second degradation reaction to obtain the wastewater after the second degradation reaction.

[0081] (5) Add a 30% sodium hydroxide solution to the wastewater after the second degradation reaction obtained in step (4), adjust the pH to 7.5, stir, so that copper ions precipitate, filter, and obtain a black solid and the treated wastewater.

[0082] Comparative Example 2

[0083] The only difference between Comparative Example 2 and Example 1 is that the amount of sodium persulfate added in step (2) of Comparative Example 2 is 12.9g, and the rest is the same as in Example 1.

[0084] Comparative Example 3

[0085] The only difference between Comparative Example 3 and Example 1 is that the amount of sodium persulfate added in step (2) of Comparative Example 3 is 24.0g, and the rest is the same as in Example 1.

[0086] Comparative Example 4

[0087] The only difference between Comparative Example 4 and Example 1 is that the stirring time for the first degradation reaction in step (2) of Comparative Example 4 is 1 hour, while the rest is the same as in Example 1.

[0088] Comparative Example 5

[0089] The only difference between Comparative Example 5 and Example 1 is that the stirring time for the first degradation reaction in step (2) of Comparative Example 5 is 7 hours, while the rest is the same as in Example 1.

[0090] Comparative Example 6

[0091] A method for treating wastewater from polyphenylene ether synthesis process includes the following steps:

[0092] (1) Add 300 mL of toluene to 1000 mL of polyphenylene ether synthesis process wastewater, stir for 10 min, let stand to separate phases, remove the light phase, and obtain the heavy phase, which is the wastewater after the first extraction.

[0093] (2) Add 50% sulfuric acid to the wastewater after the first extraction obtained in step (1) to adjust the pH to 3, add 8.3g sodium chlorate, stir at 25℃ for 4h to carry out the first degradation reaction, and obtain the wastewater after the first degradation reaction.

[0094] (3) Add 200 mL of toluene to the wastewater after the first degradation reaction obtained in step (2), stir for 10 min, let stand to separate the phases, remove the light phase, and obtain the heavy phase, which is the wastewater after the second extraction.

[0095] (4) Add 24.8g of sodium chlorate to the wastewater after the second extraction obtained in step (3), stir to dissolve, let stand at 25°C for 24h, carry out the second degradation reaction, and obtain the wastewater after the second degradation reaction.

[0096] (5) Add a 30% sodium hydroxide solution to the wastewater after the second degradation reaction obtained in step (4), adjust the pH to 7.5, stir, so that copper ions precipitate, filter, and obtain a black solid and the treated wastewater.

[0097] Comparative Example 7

[0098] A method for treating wastewater from polyphenylene ether synthesis process includes the following steps:

[0099] (1) Add 300 mL of toluene to 1000 mL of polyphenylene ether synthesis process wastewater, stir for 10 min, let stand to separate phases, remove the light phase, and obtain the heavy phase, which is the wastewater after the first extraction.

[0100] (2) Add 50% sulfuric acid to the wastewater after the first extraction obtained in step (1) to adjust the pH to 3, add 8.8g of hydrogen peroxide with a mass fraction of 30%, stir at 25°C for 4h to carry out the first degradation reaction, and obtain the wastewater after the first degradation reaction.

[0101] (3) Add 200 mL of toluene to the wastewater after the first degradation reaction obtained in step (2), stir for 10 min, let stand to separate the phases, remove the light phase, and obtain the heavy phase, which is the wastewater after the second extraction.

[0102] (4) Add 26.4g of 30% hydrogen peroxide to the wastewater after the second extraction obtained in step (3), stir evenly, let stand at 25°C for 24h, and carry out the second degradation reaction to obtain the wastewater after the second degradation reaction.

[0103] (5) Add a 30% sodium hydroxide solution to the wastewater after the second degradation reaction obtained in step (4), adjust the pH to 7.5, stir, and obtain the treated wastewater.

[0104] Performance testing

[0105] Add 2 mL of the wastewater treated in Examples 1-4 and Comparative Examples 1-7 to the COD pre-prepared tube reagent (purchased from Hach, USA). Digest the wastewater at 165°C for 20 min using a digester, cool to room temperature, and test the COD of the wastewater using a COD analyzer. The test results are shown in Table 1.

[0106] Table 1: COD of wastewater treated by the methods of Examples 1-4 and Comparative Examples 1-7

[0107]

[0108] As can be seen from Table 1, the treatment method of the present invention can significantly reduce the COD of wastewater, reducing the COD of polyphenylene ether synthesis process wastewater from 18,500 mg / L to below 400 mg / L, or even as low as 206 mg / L.

[0109] Comparative Example 1, which involved two extractions before the degradation reaction (i.e., a second toluene extraction followed by the first degradation reaction), resulted in a wastewater COD of 3550 mg / L, significantly higher than the 262 mg / L in Example 1. This indicates that a good COD removal effect can only be achieved by performing a first degradation reaction followed by a second toluene extraction. This is because after oxidation with sodium persulfate, some water-soluble organic matter in the water is converted into oxidation intermediates with higher solubility in toluene. Toluene extraction transfers these oxidation intermediates to the toluene phase, reducing the COD of the wastewater.

[0110] Comparative Example 2 used less sodium persulfate in the first degradation reaction, resulting in a treated wastewater COD of 1720 mg / L. Comparative Example 3 used more sodium persulfate in the first degradation reaction, resulting in a treated wastewater COD of 574 mg / L, both higher than the 262 mg / L in Example 1. This indicates that insufficient sodium persulfate cannot completely convert the organic matter in the wastewater into toluene-soluble oxidation intermediates; while excessive sodium persulfate can further oxidize the oxidation intermediates. Both of these factors affect the effectiveness of the second toluene extraction, thus impacting the wastewater treatment efficiency and leading to higher COD values ​​in Comparative Examples 2 and 3. Therefore, the amount of sodium persulfate used in the first oxidative degradation process must be strictly controlled.

[0111] Comparative Example 4 reduced the stirring time of the first degradation reaction to 1 hour, and the COD of the treated wastewater reached 1280 mg / L. This was because there was insufficient time for sodium persulfate to oxidize the organic matter. In contrast, Comparative Example 5 increased the stirring time of the first degradation reaction to 7 hours, and the COD of the treated wastewater was 258 mg / L, comparable to Example 1. This indicates that after 4 hours of stirring, the first degradation reaction was essentially complete, and further extending the time had no significant effect on reducing COD. Therefore, the stirring time of the first oxidative degradation reaction must be strictly controlled.

[0112] Comparative Example 6 mainly replaced sodium persulfate in steps (2) and (4) of Example 1 with an equimolar amount of sodium chlorate. Since sodium chlorate has weak oxidizing power under alkaline conditions and its effect is poor, 50% sulfuric acid was used to adjust the pH to 3 before the first degradation reaction. The COD of the wastewater treated in Comparative Example 6 reached 2630 mg / L, far higher than the 262 mg / L in Example 1. Therefore, sodium persulfate is more suitable for the polyphenylene ether synthesis process wastewater system of this patent.

[0113] Comparative Example 7 mainly replaced sodium persulfate in steps (2) and (4) of Example 1 with an equimolar amount of hydrogen peroxide. Since hydrogen peroxide rapidly decomposes under alkaline conditions, forming a large number of bubbles, it is ineffective. Therefore, 50% sulfuric acid was used to adjust the pH to 3 before the first degradation reaction. The COD of the wastewater treated in Comparative Example 7 reached 4330 mg / L, far higher than the 262 mg / L in Example 1. Furthermore, copper ions could not be precipitated by adjusting the pH. Therefore, hydrogen peroxide is not suitable for the polyphenylene ether synthesis process wastewater system of this patent.

[0114] In summary, this invention sequentially performs a first extraction, a first oxidative degradation reaction, a second extraction, and a second oxidative degradation reaction, finally adjusting the pH to precipitate copper ions. By re-extracting the oxidation intermediates, the COD of the wastewater is significantly reduced, and the method is simple to operate and has low energy consumption. Furthermore, by oxidizing and degrading the copper ion ligands, the use of sulfides and hydrosulfides is avoided during copper ion recovery, thus preventing the introduction of sulfur ion pollutants, making it environmentally friendly. The treatment method of this invention can reduce the COD of polyphenylene ether synthesis process wastewater to below 500 mg / L, and even as low as 206 mg / L, representing a 98.9% reduction in wastewater COD.

[0115] The above embodiments are only used to illustrate the technical solutions of the present invention and are not intended to limit the scope of protection of the present invention. Although the present invention has been described in detail with reference to preferred embodiments, those skilled in the art should understand that modifications or equivalent substitutions can be made to the technical solutions of the present invention without departing from the essence and scope of the technical solutions of the present invention.

Claims

1. A method for treating wastewater from the polyphenylene ether synthesis process, characterized in that, Includes the following steps: (1) Add an aromatic solvent to the wastewater from the polyphenylene ether synthesis process for the first extraction; then add sodium persulfate for the first degradation reaction; then add an aromatic solvent for the second extraction; then add sodium persulfate for the second degradation reaction to obtain the wastewater after the second degradation reaction; (2) Adjust the pH of the wastewater after the second degradation reaction obtained in step (1) to neutral or alkaline, filter it, and complete the treatment of wastewater from the polyphenylene ether synthesis process. The wastewater from the polyphenylene ether synthesis process includes a complex of triacetate and copper ions, bromide ions, and tertiary amine compounds. During the first degradation reaction, the ratio of the concentration of sodium persulfate to the chemical oxygen demand of the polyphenylene ether synthesis process wastewater is (0.8-1.2):

1.

2. The processing method according to claim 1, characterized in that, The pH of the wastewater from the polyphenylene ether synthesis process is 10-13; and / or the chemical oxygen demand (COD) of the wastewater from the polyphenylene ether synthesis process is 10000-20000 mg / L.

3. The processing method according to claim 1, characterized in that, The aromatic solvent includes at least one of toluene and xylene.

4. The processing method according to claim 1, characterized in that, In step (1), during the first extraction, the volume ratio of the aromatic solvent to the polyphenylene ether synthesis process wastewater is (0.1-0.5):

1.

5. The processing method according to claim 1, characterized in that, In step (1), the reaction temperature of the first degradation reaction is 5-40℃, and the reaction time of the first degradation reaction is 2-6h.

6. The processing method according to claim 1, characterized in that, In step (1), during the second extraction, the volume ratio of the aromatic solvent to the polyphenylene ether synthesis process wastewater is (0.1-0.3):

1.

7. The processing method according to claim 1, characterized in that, In step (1), during the second degradation reaction, the ratio of the concentration of sodium persulfate to the chemical oxygen demand of the polyphenylene ether synthesis process wastewater is (2-4):1; and / or, the reaction temperature of the second degradation reaction is 5-40℃, and the reaction time of the second degradation reaction is 18-30h.

8. The processing method according to claim 1, characterized in that, In step (2), the pH is 7-9.

9. The processing method according to any one of claims 1-8, characterized in that, In step (2), after the wastewater from the polyphenylene ether synthesis process is treated, the chemical oxygen demand of the wastewater is 200-500 mg / L.

10. The application of the treatment method according to any one of claims 1-9 in the field of wastewater treatment.

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