A method for resource-based treatment of diethyl maleate process wastewater

Abstract

The present application relates to the technical field of treatment of maleic acid-containing wastewater, and in particular to a method for resource-based treatment of diethyl maleate process wastewater, comprising: first subjecting diethyl maleate process wastewater to a hydrolysis reaction and dealcoholization treatment to obtain dealcoholized wastewater; then mixing an appropriate amount of maleic anhydride with the dealcoholized wastewater to synthesize a sodium polyepoxysuccinate solution, which is a scale inhibitor with dual effects of scale inhibition and corrosion inhibition and has a huge market demand. The treatment process steps of the present application are simple, and no high-cost environmental protection treatment equipment and material investment are required. The obtained product can be sold directly in liquid form, and no secondary wastewater and waste gas are generated throughout the process, thereby achieving high environmental protection and good economic efficiency of diethyl maleate process wastewater treatment.

Description

Technical Field

[0001] The present application relates to the technical field of treatment of maleic acid-containing wastewater, and in particular to a method for resource-based treatment of diethyl maleate process wastewater. Background Art

[0002] Diethyl maleate is an important basic chemical raw material and has great value in pesticides and synthetic resins. The preparation method of diethyl maleate usually adopts maleic anhydride, maleic acid or a mixture containing maleic anhydride and maleic acid and ethanol to be prepared by catalytic esterification. In view of process and cost considerations, the current mainstream process all adopts maleic anhydride as starting material, and is produced by batch process or continuous process, generally including the ring-opening half-esterification of maleic anhydride and anhydrous ethanol to prepare monoethyl maleate, which is then subjected to the two reaction steps of catalytic diesterization with excess ethanol. The first step half-esterification reaction usually can completely react under mild conditions and without the need for a catalyst in the presence of a catalyst, and the monoethyl maleate obtained needs to continue to carry out diesterization reaction with excess ethanol under strong acid catalysis. But the second step reaction is a reversible reaction, needs the water generated in the continuous separation system, to promote esterification to move to the forward direction, usually reaction yield is at most about 95%, and impurity is mainly monoethyl maleate in the product, also comprises a small amount of monoethyl fumarate, diethyl fumarate, maleic acid and fumaric acid etc.In addition, in the reaction system, also contain excessive alcohol and water.And in actual production, except that excess alcohol can be mostly recovered for recycling, all the other impurities need to be purified and removed.Generally first carry out rectification and purification again by alkali cleaning, water washing process, catalyzer (such as sulfuric acid, sulfonic acid etc.), monoethyl maleate and maleic acid, fumaric acid, monoethyl fumarate etc. can be removed in alkali cleaning, water washing step, the process wastewater after processing mainly contains aforementioned excessive alkali (mainly sodium carbonate), the neutralization salt and the mixed carboxylate of catalyzer, also comprises the diethyl maleate of a small amount of dissolving or sneaking into in addition, diethyl maleate solubility in water is about 2%, and also has the diethyl maleate that in the alkali cleaning process, not thoroughly causes sneaking into with oil emulsion state. In general, the total amount of wastewater accounts for about 10% to 15% of the production batch.

[0003] Conventional wastewater treatment methods for the process wastewater from diethyl maleate production require multi-stage wastewater treatment equipment, including chemical sedimentation, adsorption filtration, bio-fermentation, Fenton oxidation, and membrane separation. This not only requires investment in wastewater treatment equipment and materials, increasing the complexity of daily maintenance, but also requires separate disposal of the treated sludge as contaminated waste, further increasing treatment costs.

[0004] Patent publication number CN111689848B discloses a method for recycling and purifying maleic acid-containing wastewater. This method uses a catalytic reaction to isomerize maleic acid into fumaric acid, which is then separated and separated into a fumaric acid product. The three wastes are then treated in an oxygen-based cracking unit. However, the treatment process is complex, and a small amount of waste gas and wastewater is still discharged after the treatment is complete, causing secondary pollution. Summary of the Invention

[0005] The purpose of this application is to solve the problem that the wastewater treatment process of maleic acid is relatively complicated and a small amount of waste gas and wastewater are still discharged after the treatment is completed. The present invention provides a resource-based treatment method for diethyl maleate process wastewater with a simple treatment process and no secondary generation of wastewater and waste gas.

[0006] On the one hand, the present application provides a method for resource-based treatment of diethyl maleate process wastewater, which adopts the following technical solution:

[0007] A method for resource-based treatment of diethyl maleate process wastewater comprises the following steps:

[0008] S1: adding 1.0% to 2.0% of the mass of sodium hydroxide to the diethyl maleate process wastewater, stirring to dissolve, heating to 45-65°C, and hydrolyzing for 1-2 hours;

[0009] S2: vacuum-dealcoholizing the wastewater after hydrolysis in step S1 for 0.5 to 1 hour at a temperature of 45 to 65° C. to obtain dealcoholized wastewater;

[0010] S3: Add 90-100 parts by weight of maleic anhydride to the reactor, slowly add 320-350 parts of the dealcoholized wastewater from step S2 while maintaining stirring, and then add 140-145 parts of a 50% NaOH solution, and hydrolyze for 0.5-1 hour to obtain solution a;

[0011] S4: adding 10 to 15 parts of a catalyst to the solution a, stirring evenly, and then slowly adding dropwise a 50% hydrogen peroxide solution. After the addition is complete, controlling the temperature to 65 to 70° C. and keeping the temperature for 12 to 20 hours to obtain a solution b;

[0012] S5: Add 4 to 6 parts of initiator to the solution b, stir evenly, add 10 to 20 parts of 50% NaOH solution, control the temperature to 85 to 90° C., add 6 to 12 parts of ethylene glycol, raise the temperature to 90 to 105° C., and keep the temperature to react for 3 to 6 hours to obtain a sodium polyepoxysuccinate solution.

[0013] In the treatment of diethyl maleate process wastewater, diethyl maleate process wastewater generally needs to be treated at a cost by a wastewater treatment plant, and the industry will not reuse it. This application uses the diethyl maleate process wastewater after hydrolysis and dealcoholization treatment as a raw material to synthesize sodium polyepoxysuccinate, and the synthesized sodium polyepoxysuccinate is a scale inhibitor with dual functions of scale inhibition and corrosion inhibition, which has huge market demand. This is one of the innovations of this application; secondly, if only the treated wastewater is used to synthesize sodium polyepoxysuccinate, the solid content of the obtained solution is low, far from the solid content of the standard scale inhibitor, and secondary treatment is required. This application mixes an appropriate amount of maleic anhydride with the dealcoholization wastewater, and then synthesizes sodium polyepoxysuccinate so that its solid content reaches the level of the standard scale inhibitor, which can be sold directly in liquid form, thereby avoiding the subsequent discharge of secondary process wastewater.

[0014] In the present application, sodium hydroxide is added to diethyl maleate process wastewater, and diethyl maleate and monoethyl maleate in the wastewater undergo hydrolysis reaction under alkaline conditions to obtain sodium maleate and ethanol, and then the generated alcohol is removed by vacuum dealcoholization to obtain dealcoholized wastewater. In step S3, maleic anhydride is hydrolyzed under the action of NaOH solution to obtain sodium maleate; in step S4, sodium maleate is oxidized by hydrogen peroxide under catalytic conditions to generate sodium epoxysuccinate; in step S5, sodium epoxysuccinate undergoes polymerization reaction under the action of an initiator to obtain polyepoxy sodium succinate, wherein ethylene glycol can act as a polymerization initiator and chain transfer agent in the polymerization reaction, and can adjust the polymerization reaction rate and the molecular weight distribution of the polyepoxy sodium succinate, thereby improving the performance of the polyepoxy sodium succinate. The treatment process steps of the present application are simple, and no high-cost environmental protection treatment equipment and material investment are required. The obtained product can be sold directly in liquid form, and no secondary wastewater and waste gas are generated throughout the process, thereby achieving high environmental protection and good economic efficiency in the treatment of diethyl maleate process wastewater.

[0015] In step S4, the catalyst is sodium tungstate dihydrate.

[0016] By adopting the above technical solution, sodium tungstate dihydrate is used as a catalyst, which has good catalytic activity, can promote the epoxidation reaction of maleic acid, and increase the reaction rate.

[0017] Optionally, based on the molar amount of H2O2, the added amount of hydrogen peroxide is 1.2 to 1.5 times the molar amount of maleic anhydride.

[0018] By adopting the above technical solution, during the epoxidation reaction, part of the hydrogen peroxide will decompose to generate water and oxygen; therefore, adding excess hydrogen peroxide can fully carry out the reaction, increase the yield and purity of sodium polyepoxysuccinate, and thus improve its scale inhibition performance.

[0019] Optionally, the initiator is calcium hydroxide.

[0020] By adopting the above technical solution, calcium hydroxide can effectively initiate the polymerization reaction, improve the reaction rate and efficiency, and enable the reaction to be completed in a shorter time.

[0021] Optionally, in step S3, NaOH solution is added to adjust the pH value of the reaction solution to 5.0-7.0.

[0022] By adopting the above technical solution, maleic anhydride and monoethyl maleate in the wastewater will produce a large amount of acid during the hydrolysis reaction, causing the pH of the solution to decrease; and in the epoxidation reaction in step S4, if the pH value is too low, the epoxy group in the sodium epoxysuccinate will be activated, and it will be easily opened by the addition of water, alcohol, carboxylic acid, etc. to obtain tartaric acid or a similar structure by-product, while if the pH value is too high, a large amount of hydrogen peroxide will be decomposed into oxygen and water. Therefore, adjusting the pH value of the reaction solution to a weak acid or neutral state can improve the yield of the product.

[0023] Optionally, in step S5, NaOH solution is added to adjust the pH value of the reaction solution to above 12.0.

[0024] By adopting the above technical solution, during the synthesis process of sodium polyepoxysuccinate, in a highly alkaline environment, the polymerization reaction can be promoted and the side reactions can be suppressed, thereby improving the yield and purity of the product.

[0025] Optionally, the mass percentage of maleic acid monoester and diethyl maleate in the diethyl maleate process wastewater is 8% to 12%.

[0026] On the other hand, the present application provides a sodium polyepoxysuccinate solution, which adopts the following technical solution:

[0027] A sodium polyepoxysuccinate solution is obtained by adopting the resource recovery treatment method of the present application.

[0028] By adopting the above technical solution and utilizing resource recovery treatment methods, sodium polyepoxysuccinate can be efficiently synthesized, the cost of scale inhibitors can be reduced, and resource recovery and reuse can be achieved.

[0029] In summary, this application includes at least one of the following beneficial technical effects:

[0030] 1. The treatment process of this application is simple, does not require high-cost environmental protection treatment equipment and materials, and the obtained product can be sold directly in liquid form. No secondary wastewater and waste gas are generated throughout the process, achieving high environmental protection and good economic efficiency in the treatment of diethyl maleate process wastewater.

[0031] 2. During the epoxidation reaction, some hydrogen peroxide decomposes to produce water and oxygen; therefore, adding excess hydrogen peroxide can fully promote the reaction, increase the yield and purity of sodium polyepoxysuccinate, and thus improve its scale inhibition performance; 3. Utilizing resource recovery methods, sodium polyepoxysuccinate can be efficiently synthesized, reducing the cost of scale inhibitors and achieving resource recovery and reuse. DETAILED DESCRIPTION

[0032] To avoid redundancy, the items used in the following examples are all commercially available products unless otherwise specified, and the methods used are all conventional methods unless otherwise specified.

[0033] The present application is further described in detail below with reference to the following examples and comparative examples.

[0034] Example

[0035] Example 1

[0036] The preparation method of the polyepoxy sodium succinate solution provided in this embodiment comprises the following steps:

[0037] S1: Add 800g of diethyl maleate process wastewater and 8g of sodium hydroxide to a 1L three-necked flask, stir thoroughly to dissolve, heat to 65°C, and hydrolyze for 2h until there is no stratification on the surface of the solution and no oil droplets or turbidity;

[0038] S2: The hydrolyzed wastewater is vacuum-dealcoholized for 1 h at 65°C to obtain dealcoholized wastewater;

[0039] S3: In another 1L three-necked flask, add 98g of maleic anhydride, and slowly add 320g of dealcoholized wastewater while stirring. Then add 140g of 50% NaOH solution, adjust the pH to 7.0, and hydrolyze for 1h to obtain solution a.

[0040] S4: Add 12 g of catalyst to solution a, stir evenly, and slowly dropwise add 100 g of 50% hydrogen peroxide solution. After the addition is complete, control the temperature to 70°C and keep the temperature for 15 hours to obtain solution b.

[0041] S5: Add 5 g of calcium hydroxide to solution b, stir evenly, add 16 g of 50% NaOH solution, adjust the pH to above 12.0, control the temperature to 90°C, add 8 g of ethylene glycol, then raise the temperature to 95°C, and keep the reaction for 5 hours to obtain a sodium polyepoxysuccinate solution.

[0042] Example 2

[0043] The difference between this embodiment and embodiment 1 is that in step S1, the amount of sodium hydroxide added is 12 g.

[0044] Example 3

[0045] The difference between this embodiment and embodiment 1 is that in step S3, the amount of sodium hydroxide added is 16 g.

[0046] Example 4

[0047] The difference between this embodiment and embodiment 2 is that in step S3, the amount of dealcoholization wastewater added is 290 g.

[0048] Example 5

[0049] The difference between this embodiment and embodiment 2 is that in step S3, the amount of dealcoholization wastewater added is 350 g.

[0050] Example 6

[0051] The difference between this embodiment and embodiment 2 is that in step S5, the amount of ethylene glycol added is 6 g.

[0052] Example 7

[0053] The difference between this embodiment and embodiment 2 is that in step S5, the amount of ethylene glycol added is 10 g.

[0054] Example 8

[0055] The difference between this embodiment and embodiment 2 is that in step S5, the amount of ethylene glycol added is 12 g.

[0056] Comparative Example

[0057] Comparative Example 1

[0058] The preparation method of the polyepoxy sodium succinate solution provided in this embodiment comprises the following steps:

[0059] S3: Add 98 g of maleic anhydride to another 1 L three-necked flask, slowly add 320 g of dealcoholized wastewater while maintaining stirring, then add 140 g of 50% NaOH solution, adjust the pH to 7, and hydrolyze for 1 hour to obtain solution a; S4: Add 12 g of catalyst to solution a, stir evenly, and slowly add 100 g of 50% hydrogen peroxide solution dropwise. After the addition is complete, control the temperature to 70°C and keep the temperature for 15 hours to obtain solution b;

[0060] S5: Add 5 g of calcium hydroxide to solution b, stir evenly, add 16 g of 50% NaOH solution, adjust the pH to above 12, control the temperature to 90°C, add 8 g of ethylene glycol, then raise the temperature to 95°C, and keep the reaction warm for 5 hours to obtain a sodium polyepoxysuccinate solution.

[0061] Comparative Example 2

[0062] The preparation method of the polyepoxy sodium succinate solution provided in this embodiment comprises the following steps:

[0063] S1: Add 800g of diethyl maleate process wastewater and 12g of sodium hydroxide to a 1L three-necked flask, stir thoroughly to dissolve, heat to 65°C, and hydrolyze for 2h until there is no stratification on the surface of the solution and no oil droplets or turbidity;

[0064] S2: The hydrolyzed wastewater is vacuum-dealcoholized for 1 h at 65°C to obtain dealcoholized wastewater;

[0065] S3: In another 1L three-necked flask, add 98g of deionized water, and slowly add 320g of dealcoholized wastewater while maintaining stirring. Then, add 50% NaOH solution, adjust the pH to 7, and hydrolyze for 1h to obtain solution a.

[0066] S4: Add 12 g of catalyst to solution a, stir evenly, and slowly dropwise add 100 g of 50% hydrogen peroxide solution. After the addition is complete, control the temperature to 70°C and keep the temperature for 15 hours to obtain solution b.

[0067] S5: Add 5 g of calcium hydroxide to solution b, stir evenly, add 50% mass concentration of NaOH solution, adjust the pH to above 12, control the temperature to 90°C, add 8 g of ethylene glycol, and then raise the temperature to 95°C. Keep the temperature for reaction for 5 hours to obtain sodium polyepoxysuccinate solution.

[0068] Comparative Example 3

[0069] The difference between this comparative example and Example 2 is that in step S5, the amount of ethylene glycol added is 0.

[0070] In order to intuitively present the formulation data of all embodiments and comparative examples, Table 1 is prepared as follows:

[0071] Table 1: Formulation data of Examples 1 to 8 and Comparative Examples 1 to 3

[0072]

[0073] Performance Testing

[0074] The following performance tests were performed on the sodium polyepoxysuccinate solutions provided in Examples 1 to 8 and Comparative Examples 1 to 3 of the present application. The specific test results are shown in Table 2.

[0075] 1. Solid content

[0076] The solid content is determined by the drying method. The final sodium polyepoxysuccinate solution is weighed (total weight of the solution) and placed in a constant temperature and humidity chamber to lose moisture at a certain temperature and time. The remaining weight (solid weight) is then weighed and the solid content is calculated based on the weight of the solution and the weight of the remaining weight.

[0077] The specific calculation method is:

[0078] Solid content of solution = weight of residue / weight of solution × 100%.

[0079] 2. Scale inhibition rate

[0080] Referring to the standard of "GB / T 16632-2019 Determination of scale inhibition performance of water treatment agents - Calcium carbonate precipitation method", the scale inhibition rate of the sodium polyepoxysuccinate solution of the present application was tested.

[0081] Note: The dosage of the scale inhibitor tested is 10 mg / L, and the dosage of the scale inhibitor is calculated based on the solid weight in the sodium polyepoxysuccinate solution.

[0082] Table 2: Performance test results of Examples 1 to 8 and Comparative Examples 1 to 3

[0083] Example Solid content / % Scale inhibition rate / % Example 1 43.1 95.6 Example 2 45.4 100.0 Example 3 45.2 100.0 Example 4 42.8 99.5 Example 5 45.9 97.2 Example 6 44.4 97.0 Example 7 44.9 97.3 Example 8 44.1 95.0 Comparative Example 1 37.9 86.5 Comparative Example 2 25.5 93.9 Comparative Example 3 40.5 91.1

[0084] As shown in Tables 1-2, combined with the test results of Examples 1-3, different amounts of sodium hydroxide added during the hydrolysis reaction of diethyl maleate process wastewater affect the performance of polysodium epoxysuccinate. The addition of sodium hydroxide can hydrolyze the diethyl maleate in the diethyl maleate process wastewater to produce sodium maleate and ethanol. If the amount of sodium hydroxide added is too small, the hydrolysis reaction is insufficient, affecting the solid content and scale inhibition performance of the polysodium epoxysuccinate. In Example 3, the addition of a larger amount of sodium hydroxide does not significantly improve the product's performance. This indicates that when the amount of sodium hydroxide added is 12g, diethyl maleate is fully hydrolyzed, and the resulting sodium epoxysuccinate has excellent solid content and scale inhibition performance.

[0085] In addition, a comparison of the test results of Example 2 and Comparative Example 1 further demonstrates that the addition of sodium hydroxide for hydrolysis and dealcoholization prior to the synthesis reaction of sodium polyepoxysuccinate can effectively increase the solids content of sodium polyepoxysuccinate. In Comparative Example 1, although the diethyl maleate process wastewater was not hydrolyzed, the addition of sodium hydroxide solution during the subsequent reaction also caused the diethyl maleate to undergo hydrolysis, resulting in a final product solids content of 37.9%. However, due to the lack of dealcoholization, the sodium polyepoxysuccinate solution contained a relatively high amount of alcohol, which compromised the scale inhibition performance of the sodium polyepoxysuccinate.

[0086] The test results of Examples 2, 4, and 5 show that by adjusting the amount of dealcoholization wastewater added, polyepoxy sodium succinate solutions with varying solid contents can be obtained. When 320 g of dealcoholization wastewater was added, the resulting polyepoxy sodium succinate solution had a solid content of 45.4%, meeting the standards of commercially available scale inhibitors and exhibiting optimal scale inhibition performance. However, in Example 5, the scale inhibition performance of the polyepoxy sodium succinate solution decreased compared to that of Example 2. This is because the dealcoholization wastewater was not fully reacted, resulting in the incorporation of impurities into the product, which affected the scale inhibition performance of the polyepoxy sodium succinate.

[0087] In addition, by comparing the test results of Example 2 and Comparative Example 2, it can be seen that when maleic anhydride is replaced with deionized water and only dealcoholized wastewater is used as a raw material to synthesize sodium polyepoxysuccinate, the solid content of the product is far below the commercial standard, and secondary treatment is required to adjust the solid content of the sodium polyepoxysuccinate solution.

[0088] Combined with the test results of Examples 2, 6-8, it can be seen that the addition of ethylene glycol to the polymerization reaction of sodium epoxysuccinate can act as a polymerization initiator and chain transfer agent, regulating the polymerization reaction rate and the molecular weight distribution of sodium polyepoxysuccinate, thereby improving the scale inhibition performance of sodium polyepoxysuccinate and increasing the efficiency of the polymerization reaction. In Example 6, the amount of ethylene glycol added was relatively small, and the performance of the obtained product was inferior to that of Example 2. This may be because insufficient ethylene glycol addition may lead to incomplete polymerization, resulting in a decrease in product molecular weight, making it difficult to control the polymerization process and resulting in performance degradation. In contrast, in Examples 7-8, the addition of a large amount of ethylene glycol may result in an excessively broad molecular weight distribution and an excessively low molecular weight of the generated sodium polyepoxysuccinate, affecting product stability and, consequently, the scale inhibition performance of the sodium epoxysuccinate solution. Therefore, it can be seen that when the amount of ethylene glycol added was 8g, the scale inhibition performance of the obtained sodium polyepoxysuccinate solution was optimal.

[0089] In addition, the comparison of the test results of Example 2 and Comparative Example 3 further illustrates that ethylene glycol can effectively promote the polymerization reaction, increase the solid content of the sodium polyepoxysuccinate solution, and optimize the molecular weight and molecular weight distribution of the sodium polyepoxysuccinate, thereby improving its scale inhibition performance.

[0090] In summary, the best embodiment among all the embodiments of this application is Example 2. The solid content of the prepared sodium polyepoxysuccinate solution is 45.4%, and the scale inhibition rate is 100.0%, which meets the standards of commercially available scale inhibitors and can be sold directly in liquid form without the need for secondary treatment, and at a lower cost, thereby achieving high environmental protection and good economic efficiency in the treatment of diethyl maleate process wastewater.

[0091] The embodiments of this specific implementation are all preferred embodiments of this application and are not intended to limit the scope of protection of this application. Therefore, any equivalent changes made based on the structure, shape, and principle of this application should be included in the scope of protection of this application.

Claims

1. A method for resource-based treatment of diethyl maleate process wastewater, characterized in that: The following steps are involved: S1: Add 1.0% to 2.0% of the mass of sodium hydroxide to the diethyl maleate process wastewater, stir and dissolve, raise the temperature to 45 to 65°C, and hydrolyze for 1 to 2 hours; S2: vacuum-dealcoholizing the wastewater after hydrolysis in step S1 for 0.5 to 1 hour at a temperature of 45 to 65° C. to obtain dealcoholized wastewater; S3: Add 90-100 parts by weight of maleic anhydride to the reactor, slowly add 320-350 parts of the dealcoholized wastewater from step S2 while stirring, and then add 140-145 parts of a 50% NaOH solution, and neutralize for 0.5-1 hour to obtain solution a; S4: Add 10-15 parts of the catalyst to the solution a, stir evenly, and slowly dropwise add a hydrogen peroxide solution having a mass concentration of 30%-50%. After the dropwise addition is complete, control the temperature to 65-70° C. and keep the temperature for 12-20 hours to obtain a solution b; S5: Add 4 to 6 parts of initiator to the solution b, stir evenly, add 10 to 20 parts of 50% NaOH solution, control the temperature to 85 to 90°C, then add 6 to 12 parts of ethylene glycol, raise the temperature to 90 to 105°C, and keep the temperature to react for 3 to 6 hours to obtain a sodium polyepoxysuccinate solution.

2. A method for resource-based treatment of diethyl maleate process wastewater according to claim 1, characterized in that: In step S4, the catalyst is sodium tungstate dihydrate.

3. A method for resource-based treatment of diethyl maleate process wastewater according to claim 1, characterized in that: Calculated on the molar amount of H2O2, the added amount of hydrogen peroxide is 1.2 to 1.5 times the molar amount of maleic anhydride.

4. A method for resource-based treatment of diethyl maleate process wastewater according to claim 1, characterized in that: The initiator is calcium hydroxide.

5. A method for resource-based treatment of diethyl maleate process wastewater according to claim 4, characterized in that: In step S3, NaOH solution is added to adjust the pH value of the reaction solution to 5.0-7.

0.

6. A method for resource-based treatment of diethyl maleate process wastewater according to claim 1, characterized in that: In step S5, NaOH solution is added to adjust the pH value of the reaction solution to above 12.

0.

7. A method for resource-based treatment of diethyl maleate process wastewater according to claim 1, characterized in that: The total mass percentage of maleic acid monoester and diethyl maleate in the diethyl maleate process wastewater is 8% to 12%.

Images