Treatment method and application of wastewater of polyphenyl ether synthesis process

Abstract

The invention belongs to the technical field of wastewater treatment, and particularly relates to a treatment method and application of polyphenyl ether synthesis process wastewater. The treatment method of the wastewater of the polyphenyl ether synthesis process comprises the following steps: adding an aromatic solvent into the wastewater of the polyphenyl ether synthesis process, and carrying out first extraction; then adding sodium persulfate, and carrying out a first degradation reaction; adding an aromatic solvent, and extracting for the second time; then adding sodium persulfate, and carrying out a second degradation reaction to obtain wastewater after the second degradation reaction; and adjusting the pH value of the wastewater after the second degradation reaction to be neutral or alkaline, and filtering to complete wastewater treatment. The oxidation intermediate product is extracted again, the COD of the wastewater is greatly reduced, the COD of the wastewater of the polyphenyl ether synthesis process can be reduced to 500 mg / L or below, even 206 mg / L, the COD of the wastewater is reduced by 98.9%, and the method is easy to operate, low in energy consumption and environmentally friendly.

Description

Technical Field

[0001] The invention belongs to the technical field of wastewater treatment, and particularly relates to a method for treating wastewater from a polyphenylene ether synthesis process and application thereof. Background Art

[0002] Polyphenylene ether has excellent heat resistance and dielectric properties, and is one of the ideal resin materials for high-frequency and high-speed copper-clad laminates. However, polyphenylene ether with conventional molecular weight has high melt viscosity and poor fluidity, making it difficult to be used in copper-clad laminate manufacturing. Therefore, the industry generally uses difunctional low molecular weight polyphenylene ether as the resin raw material for high-frequency and high-speed copper-clad laminates.

[0003] A typical method for preparing bifunctional low molecular weight polyphenylene ether includes: under the catalytic conditions of copper amine complex, tetramethyl bisphenol A and 2,6-dimethylphenol are subjected to oxidative copolymerization reaction, after the reaction, chelating agents are added in sequence to chelate and extract copper ions, alkali solution is added to react and extract residual phenolic monomers, and deionized water is added for washing and purification. In actual production, about 400 kg of wastewater is generated for every ton of product produced. At the same time, in the oxidative copolymerization reaction, tetramethyl bisphenol A has low activity, and generally the amount of copper amine complex catalyst needs to be increased. Therefore, this type of wastewater contains higher concentrations of sodium phenolate, organic amines and copper ion chelates, and has a higher chemical oxygen demand (COD), which needs to be pretreated before it can be discharged into the sewage treatment plant.

[0004] Due to the complex composition of such industrial wastewater, it is impossible to directly and effectively treat it only by conventional Fenton oxidation, distillation and biodegradation methods. At present, a method for treating polyphenylene ether process wastewater has been disclosed, which sequentially performs alkali treatment, aeration treatment and distillation treatment to thoroughly separate difficult-to-treat phenolic substances, amine-containing substances and low-molecular polyphenylene ethers so that the process wastewater meets the standards. However, this method uses a distillation process with a reflux ratio of 2-3 and high energy consumption. At the same time, this method cannot effectively recycle copper ions. Chelated copper ions have high stability and usually require the use of sodium sulfide or sodium hydrosulfide to precipitate them, but this will inevitably introduce sulfide ion pollutants.

[0005] Therefore, it is of great significance to provide a method for treating wastewater from the polyphenylene ether synthesis process which has low energy consumption, can effectively reduce the COD of wastewater, and is green and environmentally friendly. Summary of the invention

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

[0007] The inventive concept of the present invention: The method for treating wastewater from the synthesis process of polyphenylene ether of the present invention is as follows: adding an aromatic solvent to the wastewater from the synthesis process of polyphenylene ether to perform a first extraction; then adding sodium persulfate to perform a first degradation reaction; then adding an aromatic solvent 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 treatment of wastewater from the synthesis process of polyphenylene ether. The present invention sequentially performs a first extraction, a first oxidation degradation, a second extraction, and a second oxidation degradation, and finally adjusts the pH to precipitate copper ions. The method is simple to operate and has low energy consumption. By extracting the oxidation intermediate product again, the COD of the wastewater is greatly reduced. At the same time, by oxidizing and degrading the copper ion ligand, the use of sulfide and hydrosulfide is avoided in the process of recovering copper ions, thereby avoiding the introduction of sulfide ion pollutants, and being green and environmentally friendly. The treatment method of the present invention can reduce the COD of wastewater from the synthesis process of polyphenylene ether to below 500 mg / L.

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

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

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

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

[0012] Preferably, the wastewater from the polyphenylene ether synthesis process comprises a complex of nitrilotriacetate 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 10000-20000 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 wastewater from the polyphenylene ether synthesis process is (0.1-0.5):1; further preferably, in step (1), during the first extraction, the volume ratio of the aromatic solvent to the wastewater from the polyphenylene ether synthesis process is (0.2-0.4):1.

[0018] Preferably, in step (1), the first extraction is carried out by adding an aromatic solvent, stirring for 5-30 minutes, standing for phase separation, removing the light phase, and obtaining a heavy phase, i.e., waste water 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; further 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°C, and the reaction time of the first degradation reaction is 2-6h; further preferably, the reaction temperature of the first degradation reaction is 15-30°C, 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. Further controlling the amount of sodium persulfate added and the stirring time is beneficial to improving 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; further 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 is carried out by adding an aromatic solvent, stirring for 5-30 minutes, standing for phase separation, removing the light phase, and obtaining a heavy phase, i.e., waste water 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; further 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°C, and the reaction time of the second degradation reaction is 18-30h; further preferably, the reaction temperature of the second degradation reaction is 15-30°C, 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 to react.

[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 COD of the final wastewater. By further controlling the amount of sodium persulfate added and the stirring time, it is beneficial to improve the treatment effect of the wastewater.

[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 base comprises sodium hydroxide.

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

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

[0033] Preferably, in step (2), after the treatment of the wastewater from the polyphenylene ether synthesis process is completed, the COD of the wastewater is 200-500 mg / L; further preferably, in step (2), after the treatment of the wastewater from the polyphenylene ether synthesis process is completed, 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 a polyphenylene ether synthesis process according to the first aspect of the present invention in the field of wastewater treatment.

[0035] Compared with the prior art, the technical solution provided by the present invention has the following beneficial effects:

[0036] (1) The present invention first uses an aromatic solvent for the first extraction, then adds sodium persulfate for the first oxidation degradation, then uses an aromatic solvent for the second extraction of the first oxidation degradation product, then uses sodium persulfate for the second oxidation degradation, and finally adjusts the pH to precipitate copper ions. The method is simple to operate and has low energy consumption. By extracting the oxidation intermediate product again, the COD of the wastewater is greatly reduced. In addition, by oxidizing and degrading the copper ion ligand, the use of sulfide and hydrosulfide is avoided in the process of recovering copper ions, thereby avoiding the introduction of sulfide ion pollutants, which is green and environmentally friendly. The treatment method of the present invention can reduce the COD of the wastewater from the polyphenylene ether synthesis process to less than 500 mg / L, and even to 206 mg / L, and the COD of the wastewater is reduced by 98.9%.

[0037] (2) During 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, the effect of the second extraction is improved, thereby achieving the purpose of significantly reducing the COD after wastewater treatment. DETAILED DESCRIPTION

[0038] In order to make the technical scheme of the present invention more clearly understood by those skilled in the art, the following embodiments are listed for illustration. It should be pointed out that the following embodiments do not limit the protection scope of the present invention.

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

[0040] The polyphenylene ether synthesis process wastewater used in the embodiments and comparative examples of the present invention is obtained by the following synthesis method, which specifically includes the following steps:

[0041] (1) Add 250 kg of 2,6-dimethylphenol, 50 kg of tetramethyl bisphenol A, and 1000 kg of toluene to a reactor, stir until all the 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 well, and introduce oxygen (15 Nm 3 / min), react at 40°C for 200min; after the reaction, add 37.5kg of 5% trisodium nitrilotriacetate aqueous solution, stir and react at 70°C for 60min, then centrifuge the liquid to obtain a light phase polyphenylene ether solution and a heavy phase chelated copper ion wastewater W1;

[0042] (2) adding 10 kg of 5% by mass sodium hydroxide solution to the light phase polyphenylene ether solution obtained in step (1), stirring and reacting at 70° C. for 60 min, and then centrifuging the liquid to obtain a light phase polyphenylene ether solution and alkali washing wastewater W2;

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

[0044] The heavy phase chelated copper ion wastewater W1, alkali washing wastewater W2 and water washing wastewater W3 constitute the wastewater of the polyphenylene ether synthesis process. The pH of the wastewater is 11, the COD is 18500 mg / L, and it is dark green.

[0045] Example 1

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

[0047] (1) Add 300 mL of toluene to 1000 mL of polyphenylene ether synthesis process wastewater, stir for 10 min, stand for phase separation, remove the light phase, and obtain the heavy phase, i.e., the wastewater after the first extraction;

[0048] (2) adding 18.5 g of sodium persulfate to the wastewater after the first extraction obtained in step (1), stirring at a temperature of 25° C. for 4 hours to perform a first degradation reaction, and obtaining wastewater after the first degradation reaction;

[0049] (3) adding 200 mL of toluene to the wastewater after the first degradation reaction obtained in step (2), stirring for 10 min, standing for phase separation, removing the light phase, and obtaining the heavy phase, i.e., the wastewater after the second extraction;

[0050] (4) adding 55.5 g of sodium persulfate to the wastewater after the second extraction obtained in step (3), stirring to dissolve, and standing at a temperature of 25° C. for 24 hours to perform a second degradation reaction to obtain wastewater after the second degradation reaction;

[0051] (5) adding a sodium hydroxide solution with a mass fraction of 30% to the wastewater after the second degradation reaction obtained in step (4), adjusting the pH to 7.5, stirring to cause a precipitation reaction of copper ions, filtering, and obtaining a black solid and treated wastewater.

[0052] Example 2

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

[0054] (1) Add 200 mL of toluene to 1000 mL of polyphenylene ether synthesis process wastewater, stir for 10 min, stand for phase separation, remove the light phase, and obtain the heavy phase, i.e., the wastewater after the first extraction;

[0055] (2) adding 20.3 g of sodium persulfate to the wastewater after the first extraction obtained in step (1), stirring at a temperature of 25° C. for 4 hours to carry out a first degradation reaction, and obtaining wastewater after the first degradation reaction;

[0056] (3) adding 250 mL of toluene to the wastewater after the first degradation reaction obtained in step (2), stirring for 10 min, standing for phase separation, removing the light phase, and obtaining the heavy phase, i.e., the wastewater after the second extraction;

[0057] (4) adding 59.2 g of sodium persulfate to the wastewater after the second extraction obtained in step (3), stirring and dissolving, and standing at a temperature of 25° C. for 28 h to perform a second degradation reaction to obtain wastewater after the second degradation reaction;

[0058] (5) adding a sodium hydroxide solution with a mass fraction of 30% to the wastewater after the second degradation reaction obtained in step (4), adjusting the pH to 8, stirring to cause a precipitation reaction of copper ions, filtering, and obtaining a black solid and treated wastewater.

[0059] Example 3

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

[0061] (1) Add 300 mL of toluene to 1000 mL of polyphenylene ether synthesis process wastewater, stir for 15 min, stand for phase separation, remove the light phase, and obtain the heavy phase, i.e., the wastewater after the first extraction;

[0062] (2) adding 18.5 g of sodium persulfate to the wastewater after the first extraction obtained in step (1), stirring at a temperature of 15° C. for 6 hours to perform a first degradation reaction, and obtaining wastewater after the first degradation reaction;

[0063] (3) adding 200 mL of toluene to the wastewater after the first degradation reaction obtained in step (2), stirring for 15 min, standing for phase separation, removing the light phase, and obtaining the heavy phase, i.e., the wastewater after the second extraction;

[0064] (4) adding 55.5 g of sodium persulfate to the wastewater after the second extraction obtained in step (3), stirring to dissolve, and standing at a temperature of 15° C. for 24 hours to perform a second degradation reaction to obtain wastewater after the second degradation reaction;

[0065] (5) adding a sodium hydroxide solution with a mass fraction of 30% to the wastewater after the second degradation reaction obtained in step (4), adjusting the pH to 9, stirring to cause a precipitation reaction of copper ions, filtering, and obtaining a black solid and treated wastewater.

[0066] Example 4

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

[0068] (1) Add 250 mL of toluene to 1000 mL of polyphenylene ether synthesis process wastewater, stir for 10 min, stand for phase separation, remove the light phase, and obtain the heavy phase, i.e., the wastewater after the first extraction;

[0069] (2) adding 14.8 g of sodium persulfate to the wastewater after the first extraction obtained in step (1), stirring at a temperature of 30° C. for 4 hours to perform a first degradation reaction, and obtaining wastewater after the first degradation reaction;

[0070] (3) adding 200 mL of toluene to the wastewater after the first degradation reaction obtained in step (2), stirring for 10 min, standing for phase separation, removing the light phase, and obtaining the heavy phase, i.e., the wastewater after the second extraction;

[0071] (4) adding 64.7 g of sodium persulfate to the wastewater after the second extraction obtained in step (3), stirring and dissolving, and standing at a temperature of 30° C. for 20 h to perform a second degradation reaction to obtain wastewater after the second degradation reaction;

[0072] (5) adding a sodium hydroxide solution with a mass fraction of 30% to the wastewater after the second degradation reaction obtained in step (4), adjusting the pH to 7, stirring to cause a precipitation reaction of copper ions, filtering, and obtaining a black solid and treated wastewater.

[0073] When treating the wastewater from the synthesis process of polyphenylene ether in Examples 1-4 of the present invention, obvious experimental phenomena were observed. In Example 1, after sodium persulfate was added in step (2) and stirred for 4 hours for the first degradation reaction, the wastewater changed from the original dark green to blue; after sodium persulfate was added in step (4) and allowed to stand for 24 hours for the second degradation reaction, the wastewater changed from blue to bright green; after sodium hydroxide solution was added 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 wastewater after filtration was colorless and transparent.

[0074] Comparative Example 1

[0075] The only difference between Comparative Example 1 and Example 1 is that Comparative Example 1 first performs two extractions and then performs the first degradation and the second degradation. The other steps are the same as Example 1.

[0076] Specifically, the method for treating wastewater from the polyphenylene ether synthesis process of Comparative Example 1 comprises the following steps:

[0077] (1) Add 300 mL of toluene to 1000 mL of polyphenylene ether synthesis process wastewater, stir for 10 min, stand for phase separation, remove the light phase, and obtain the heavy phase, i.e., the wastewater after the first extraction;

[0078] (2) adding 200 mL of toluene to the wastewater after the first extraction obtained in step (1), stirring for 10 min, standing for phase separation, removing the light phase, and obtaining the heavy phase, i.e., the wastewater after the second extraction;

[0079] (3) adding 18.50 g of sodium persulfate to the wastewater after the second extraction obtained in step (2), stirring at a temperature of 25° C. for 4 hours to carry out a first degradation reaction, and obtaining wastewater after the first degradation reaction;

[0080] (4) adding 55.50 g of sodium persulfate to the wastewater after the first degradation reaction obtained in step (3), stirring and dissolving, standing at a temperature of 25° C. for 24 h, and performing a second degradation reaction to obtain wastewater after the second degradation reaction;

[0081] (5) adding a sodium hydroxide solution with a mass fraction of 30% to the wastewater after the second degradation reaction obtained in step (4), adjusting the pH to 7.5, stirring to cause a precipitation reaction of copper ions, filtering, and obtaining a black solid and treated wastewater.

[0082] Comparative Example 2

[0083] The difference between Comparative Example 2 and Example 1 is that the amount of sodium persulfate added in step (2) of Comparative Example 2 is 12.9 g, and the rest is the same as 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 24.0 g, and the rest is the same as Example 1.

[0086] Comparative Example 4

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

[0088] Comparative Example 5

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

[0090] Comparative Example 6

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

[0092] (1) Add 300 mL of toluene to 1000 mL of polyphenylene ether synthesis process wastewater, stir for 10 min, stand for phase separation, remove the light phase, and obtain the heavy phase, i.e., the wastewater after the first extraction;

[0093] (2) adding 50% sulfuric acid to the wastewater after the first extraction obtained in step (1) to adjust the pH to 3, adding 8.3 g of sodium chlorate, stirring at a temperature of 25° C. for 4 hours, and performing a first degradation reaction to obtain wastewater after the first degradation reaction;

[0094] (3) adding 200 mL of toluene to the wastewater after the first degradation reaction obtained in step (2), stirring for 10 min, standing for phase separation, removing the light phase, and obtaining the heavy phase, i.e., the wastewater after the second extraction;

[0095] (4) adding 24.8 g of sodium chlorate to the wastewater after the second extraction obtained in step (3), stirring and dissolving, and standing at a temperature of 25° C. for 24 h to perform a second degradation reaction to obtain wastewater after the second degradation reaction;

[0096] (5) adding a sodium hydroxide solution with a mass fraction of 30% to the wastewater after the second degradation reaction obtained in step (4), adjusting the pH to 7.5, stirring to cause a precipitation reaction of copper ions, filtering, and obtaining a black solid and treated wastewater.

[0097] Comparative Example 7

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

[0099] (1) Add 300 mL of toluene to 1000 mL of polyphenylene ether synthesis process wastewater, stir for 10 min, stand for phase separation, remove the light phase, and obtain the heavy phase, i.e., the wastewater after the first extraction;

[0100] (2) adding 50% sulfuric acid to the wastewater after the first extraction obtained in step (1) to adjust the pH to 3, adding 8.8 g of 30% hydrogen peroxide, stirring at a temperature of 25° C. for 4 hours, and performing a first degradation reaction to obtain wastewater after the first degradation reaction;

[0101] (3) adding 200 mL of toluene to the wastewater after the first degradation reaction obtained in step (2), stirring for 10 min, standing for phase separation, removing the light phase, and obtaining the heavy phase, i.e., the wastewater after the second extraction;

[0102] (4) adding 26.4 g of 30% by mass hydrogen peroxide to the wastewater after the second extraction obtained in step (3), stirring evenly, and standing at a temperature of 25° C. for 24 hours to perform a second degradation reaction to obtain wastewater after the second degradation reaction;

[0103] (5) Adding a sodium hydroxide solution with a mass fraction of 30% to the wastewater after the second degradation reaction obtained in step (4), adjusting the pH to 7.5, stirring, and obtaining treated wastewater.

[0104] Performance Testing

[0105] 2 mL of wastewater treated with Examples 1-4 and Comparative Examples 1-7 was added to the COD prefabricated tube reagent (purchased from Hach, USA), respectively, and digested at 165° C. for 20 min using a digester, cooled to room temperature, and the COD of the wastewater was tested using a COD meter. The test results are shown in Table 1.

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

[0107]

[0108] It can be seen from Table 1 that the treatment method of the present invention can significantly reduce the COD of wastewater, and can reduce the COD of wastewater from the polyphenylene ether synthesis process from 18500 mg / L to below 400 mg / L, or even as low as 206 mg / L.

[0109] Comparative Example 1 is subjected to degradation reaction after two extractions, that is, the second toluene extraction is performed first, and then the first degradation reaction is performed. The COD of the treated wastewater is as high as 3550 mg / L, which is significantly higher than 262 mg / L in Example 1. This shows that only after the first degradation reaction and then the second toluene extraction can a better COD removal effect be achieved. This is because after the addition of sodium persulfate for oxidation, part of the water-soluble organic matter in the water is converted into an oxidation intermediate with higher solubility in toluene. The toluene extraction can transfer the part of the oxidation intermediate to the toluene phase, thereby reducing the COD of the wastewater.

[0110] Comparative Example 2 uses less sodium persulfate in the first degradation reaction, and the COD of the treated wastewater reaches 1720 mg / L, while Comparative Example 3 uses more sodium persulfate in the first degradation reaction, and the COD of the treated wastewater reaches 574 mg / L, both higher than 262 mg / L in Example 1. This shows that when sodium persulfate is insufficient, all organic matter in the wastewater cannot be converted into oxidation intermediates soluble in toluene; and when sodium persulfate is excessive, the oxidation intermediates can be further oxidized, which affects the effect of the second toluene extraction, and further affects the treatment effect of the wastewater, making the COD of Comparative Examples 2 and 3 higher. Therefore, it is necessary to strictly control the amount of sodium persulfate used in the first oxidation degradation.

[0111] In Comparative Example 4, the stirring time of the first degradation reaction was reduced to 1 h, and the COD of the treated wastewater reached 1280 mg / L, because there was not enough time for sodium persulfate to oxidize the organic matter. In Comparative Example 5, the stirring time of the first degradation reaction was increased to 7 h, and the COD of the treated wastewater was 258 mg / L, which was equivalent to Example 1. This shows that after 4 h of stirring, the first degradation reaction was basically completed, and further extension of the time had no obvious effect on COD reduction. Therefore, the stirring time of the first oxidation degradation reaction needs to be strictly controlled.

[0112] Comparative Example 6 mainly replaces the sodium persulfate in step (2) and step (4) of Example 1 with an equimolar amount of sodium chlorate. At the same time, because the oxidizing property of sodium chlorate is not strong under alkaline conditions and the effect is very poor, 50% sulfuric acid is used to adjust the pH to 3 before the first degradation reaction. The COD of the wastewater after the treatment of Comparative Example 6 reaches 2630 mg / L, which is much higher than 262 mg / L in Example 1. Therefore, sodium persulfate is more suitable for the wastewater system of the polyphenylene ether synthesis process of this patent.

[0113] Comparative Example 7 mainly replaces the sodium persulfate in step (2) and step (4) of Example 1 with an equimolar amount of hydrogen peroxide. At the same time, because hydrogen peroxide quickly decomposes under alkaline conditions to form a large number of bubbles, it cannot achieve the desired effect. Therefore, 50% sulfuric acid is also used to adjust the pH to 3 before the first degradation reaction. The COD of the wastewater treated in Comparative Example 7 reaches 4330 mg / L, which is much higher than 262 mg / L in Example 1. At the same time, copper ions cannot be precipitated by adjusting the pH. Therefore, hydrogen peroxide is not suitable for the wastewater system of the polyphenylene ether synthesis process of this patent.

[0114] In summary, the present invention sequentially performs the first extraction, the first oxidation degradation reaction, the second extraction and the second oxidation degradation reaction, and finally adjusts the pH to precipitate copper ions. By extracting the oxidation intermediate product again, the COD of the waste water is greatly reduced, and the method is simple to operate and has low energy consumption. In addition, by oxidizing and degrading the copper ion ligand, the use of sulfide and hydrosulfide is avoided in the process of recovering copper ions, thereby avoiding the introduction of sulfide ion pollutants, and being green and environmentally friendly. The COD of the waste water of the polyphenylene ether synthesis process can be reduced to less than 500 mg / L, or even to 206 mg / L by the treatment method of the present invention, and the COD of the waste water is reduced by 98.9%.

[0115] The above embodiments are only used to illustrate the technical solution of the present invention rather than to limit the protection scope of the present invention. Although the present invention has been described in detail with reference to the preferred embodiments, those skilled in the art should understand that the technical solution of the present invention can be modified or replaced by equivalents without departing from the essence and scope of the technical solution of the present invention.

Claims

1. A method for treating wastewater from a polyphenylene ether synthesis process, characterized in that: The following steps are involved: (1) adding an aromatic solvent to wastewater from a polyphenylene ether synthesis process to perform a first extraction; then adding sodium persulfate to perform a first degradation reaction; then adding an aromatic solvent to perform a second extraction; then adding sodium persulfate to perform a second degradation reaction to obtain wastewater after the second degradation reaction; (2) adjusting the pH of the wastewater after the second degradation reaction obtained in step (1) to neutral or alkaline, filtering, and completing the treatment of the wastewater from the polyphenylene ether synthesis process.

2. The processing method according to claim 1, characterized in that: The polyphenylene ether synthesis process wastewater includes a complex of nitrilotriacetate and copper ions, bromide ions and tertiary amine compounds; and / or the pH of the polyphenylene ether synthesis process wastewater is 10-13; and / or the chemical oxygen demand of the polyphenylene ether synthesis process wastewater 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 wastewater from the polyphenylene ether synthesis process is (0.1-0.5):

1.

5. The processing method according to claim 1, characterized in that: In step (1), 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; and / or, the reaction temperature of the first degradation reaction is 5-40°C, 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 wastewater from the polyphenylene ether synthesis process 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°C, 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 to 8, characterized in that: In step (2), after the treatment of the wastewater from the polyphenylene ether synthesis process is completed, the chemical oxygen demand of the wastewater is 200-500 mg / L.

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

Images