A deep recovery process for thiram production wastewater

Abstract

This invention belongs to the field of wastewater treatment technology, specifically relating to a deep recovery process for thiram production wastewater. The specific steps include: dissolving potassium persulfate and aluminum sulfate in water to prepare an initiator; sequentially adding 0.5-5 volumes of hydrogen peroxide and 0.5-5 volumes of the initiator to a reaction apparatus, mixing thoroughly, and adjusting the pH of the system to 1-7; adding 50-150 volumes of the thiram production wastewater to be treated to the reaction apparatus, stirring, and controlling the system temperature at 10℃-50℃; after the reaction is complete, restoring the system temperature to room temperature, centrifuging, and drying to obtain thiram and the treated wastewater. This invention not only obtains thiram technical from thiram production wastewater but also simultaneously reduces the COD and ammonia nitrogen content in the wastewater, lowering the COD to below 5000 mg / L and reducing the ammonia nitrogen content by up to nearly 93%, thus reducing the difficulty of subsequent treatment.

Description

Technical Field

[0001] This invention belongs to the field of wastewater treatment technology, specifically relating to a deep recovery process for thiram production wastewater. Background Technology

[0002] Thiram, with the molecular formula C6H 12 N2S4, also known as tetramethylthiuram disulfide, is a widely used sulfurization accelerator, fungicide, and seed soaking agent in industrial and agricultural fields. The traditional method for preparing thiram (sodium thiram) is the chlorine-air process, but this method generates large amounts of waste gas, wastewater, and waste salt, causing significant environmental pollution, increasing production costs, and exhibiting low process safety. Through extensive experimental research, the applicant has developed a highly efficient and green synthesis method for thiram (CN106699622 A). Compared to the traditional chlorine oxidation method, the peroxide-hydrogenation method for thiram production not only avoids the use of the highly toxic chemical chlorine, greatly reducing production safety risks, but also combines the original sodium thiram synthesis and chlorine oxidation processes into a single step, eliminating the consumption of sodium hydroxide solution in the intermediate process, simplifying the production process, and enhancing operational safety. From an environmental perspective, the traditional chlorine oxidation method generates over 10 tons of wastewater per ton of thiram, while the peroxide-hydrogenation method reduces this to 3 tons, significantly alleviating environmental pressure.

[0003] However, the COD concentration in the wastewater produced by the production of thiram is generally as high as 15,000 to 20,000 mg / L, which increases the difficulty of subsequent treatment. Moreover, the main components of this wastewater are thiram and partially dissolved carbon disulfide. Since the concentration of thiram is low, thiram cannot be generated under normal synthesis conditions. It can only be treated together with other production wastewater through subsequent conventional wastewater treatment processes and discharged after meeting the discharge standards, resulting in a waste of resources. Summary of the Invention

[0004] In view of this, the present invention provides a deep recovery process for thiram production wastewater. This deep recovery process can not only extract valuable thiram technical from the thiram production wastewater, but also reduce the COD of the wastewater to below 5000 mg / L and reduce the ammonia nitrogen content by up to nearly 93%, thereby reducing the difficulty of subsequent wastewater treatment.

[0005] To solve the above technical problems, this invention provides a deep recovery process for thiram production wastewater, comprising:

[0006] Potassium persulfate and aluminum sulfate were dissolved in water to prepare an initiator for later use.

[0007] Add 0.5–5 volumes of hydrogen peroxide and 0.5–5 volumes of the initiator sequentially into the reaction apparatus, mix well, and adjust the pH of the system to 1–7;

[0008] Add 50-150 volumes of the thiram production wastewater to be treated to the reaction equipment, stir, and control the system temperature at 10℃-50℃;

[0009] After the reaction was complete, the system temperature was restored to room temperature, and after centrifugation and drying, thiram and the treated wastewater were obtained.

[0010] The deep recovery process for thiram production wastewater provided by this invention first involves dissolving potassium persulfate and aluminum sulfate in water to prepare an initiator. Then, reagents (hydrogen peroxide - initiator - pH adjustment) are added in a specific order and proportion. Under pH conditions of 1 to 7, hydrogen peroxide aqueous solution is used as an oxidant, and potassium persulfate and aluminum sulfate are used as initiators. Together with the oxidant, they promote the continued generation of thiram from the effective materials in the thiram mother liquor (mainly unreacted raw materials and generated intermediates), thus realizing the recovery and utilization of potential thiram in the thiram production wastewater.

[0011] In conjunction with the first aspect, after adding 50-150 volumes of the thiram production wastewater to be treated to the reaction equipment and stirring, the method further includes the step of adding 200-300 volumes of the thiram production wastewater to be treated in multiple batches, and adding 0.5-5 volumes of hydrogen peroxide at the same time as each 50-150 volumes of the thiram production wastewater to be treated.

[0012] In conjunction with the first aspect, after the step of adding 200-300 volumes of the thiram production wastewater to be treated in multiple batches, and adding 0.5-5 volumes of hydrogen peroxide at the same time as adding 50-150 volumes of the thiram production wastewater to be treated, the method further includes the step of adding 0.5-5 volumes of the initiator to the reaction equipment, and then adding 200-400 volumes of the thiram production wastewater to be treated in multiple batches, and adding 0.5-5 volumes of hydrogen peroxide at the same time as adding 50-150 volumes of the thiram production wastewater to be treated.

[0013] In practical applications, the appropriate recovery process can be selected based on the specific circumstances and the volume of thiram production wastewater to be treated. When the total volume to be treated is large, adding the thiram production wastewater in batches along with hydrogen peroxide can make the reaction more complete, thereby improving the recovery rate of thiram in the thiram production wastewater.

[0014] In conjunction with the first aspect, the mass ratio of potassium persulfate to aluminum sulfate is 1:1 to 10, preferably 1:1.5 to 5, and more preferably 1:1.5 to 3.

[0015] In conjunction with the first aspect, in the initiator, the concentration of potassium persulfate is 5-50 g / L, and the concentration of aluminum sulfate is 30-50 g / L.

[0016] Preferably, in the initiator, the concentration of potassium persulfate is 18.4 g / L and the concentration of aluminum sulfate is 34.2 g / L.

[0017] In conjunction with the first aspect, in steps 1 to 7 of the pH adjustment system, the pH is adjusted using an aqueous solution of sulfuric acid, hydrochloric acid, or nitric acid. The concentration of the aqueous solution of sulfuric acid, hydrochloric acid, or nitric acid is not limited and can be selected and adjusted according to the actual situation. For example, when the system is highly alkaline, a more concentrated acidic solution can be used for adjustment. Once the pH value of the system is close to the expected value, a less concentrated acidic solution can be used for fine-tuning.

[0018] In conjunction with the first aspect, the concentration of hydrogen peroxide is 5% to 30%, preferably 10% to 28%.

[0019] In conjunction with the first aspect, the volume ratio of hydrogen peroxide added in each batch to the wastewater from the production of thiram is 1 to 10:200.

[0020] In conjunction with the first aspect, the system temperature is maintained between 35°C and 40°C throughout the reaction process. Since this reaction is exothermic and has a low start-up temperature, it is generally not necessary to take special measures to increase the system temperature; the system temperature can be controlled by combining the exothermic nature of the reaction itself with the cooling water in the jacket.

[0021] In conjunction with the first aspect, the thiram production wastewater is the thiram mother liquor generated during the preparation of thiram using the hydrogen peroxide oxidation method. The hydrogen peroxide oxidation method is a highly efficient and green synthesis method that does not require organic solvents, and the purity of the obtained thiram can reach over 98% (see CN 106699622 A). However, currently, the thiram mother liquor generated by this method is directly treated and discharged only after meeting the standards, which to some extent leads to a waste of resources.

[0022] The beneficial effects of this invention are as follows: The deep recovery process for thiram production wastewater provided by this invention takes energy saving, consumption reduction, and waste-to-treasure transformation as its starting point. It utilizes a specific initiator to perform secondary synthesis on the raw materials remaining in the mother liquor generated during the synthesis of thiram via the hydrogen peroxide oxidation method, achieving deep recovery. Not only can a certain amount of thiram technical material be obtained from the thiram mother liquor (the amount of thiram product with a content greater than 80% recovered per cubic meter of thiram production wastewater can reach more than 10 kg), but it can also reduce the chemical oxygen demand (COD) in the thiram mother liquor to below 5000 mg / L, and reduce ammonia nitrogen by up to nearly 93%, greatly reducing the difficulty of subsequent treatment of thiram production wastewater. Detailed Implementation

[0023] To make the objectives, technical solutions, and advantages of this invention clearer, the invention will be further described in detail below with reference to specific embodiments. It should be understood that the specific embodiments described herein are for illustrative purposes only and are not intended to limit the invention.

[0024] The thiram production wastewater used in the following examples and comparative examples was generated according to the hydrogen peroxide oxidation process (CN106699622 A) (i.e., the filtrate obtained after filtration—thiram mother liquor). Furthermore, the reaction vessel volume used in the following examples and comparative examples was 10 m³. 3 The volume of wastewater treated is 1-8 m³. 3 In this study, Examples 1-5 and Comparative Examples 1-3 all used the same batch of thiram production wastewater, while Examples 1 and 6-15 used different batches of thiram production wastewater. In practical applications, larger-volume reactors can also be used to treat more thiram production wastewater.

[0025] Example 1

[0026] This embodiment provides a deep recovery process for thiram production wastewater, treating 1m³ of thiram production wastewater. 3 The specific process is as follows:

[0027] Weigh out 55g of potassium persulfate and 105g of aluminum sulfate, add them to 3kg of water and stir until completely dissolved; these will serve as initiators. Add 5kg of 28% hydrogen peroxide solution to the reactor, followed by 1.58kg of the initiator, and stir until thoroughly mixed. Adjust the pH of the system to 3–3.5 with sulfuric acid solution, then add 0.2mg of [amount missing]. 3 The temperature of the TFMI (Fumaron) production wastewater system was consistently maintained between 35℃ and 40℃; subsequent additions of 0.2m³... 3 The wastewater from the production of thiram was treated with the addition of 5 kg of hydrogen peroxide until 0.6 m³ of the solution was completely added. 3 After treating the wastewater, add the remaining 1.58 kg of initiator and monitor the pH value in real time to maintain it between 3 and 3.5. Repeat this process for every 0.2 kg of initiator added. 3 The wastewater from the production of thiram was treated by adding 5 kg of hydrogen peroxide while stirring to allow the reaction to proceed until the volume of the wastewater to be treated reached 1 m³. 3 After all the wastewater was added, the reaction was stirred for another 0.5 hours. The system temperature was then lowered to room temperature, centrifuged, and the wet product of thiram was obtained. After air drying, the product was weighed to obtain the dry product of thiram.

[0028] Example 2

[0029] This embodiment provides a deep recovery process for thiram production wastewater, treating 3m³ of thiram production wastewater. 3 The specific process is as follows:

[0030] Weigh out 175g of potassium persulfate and 325g of aluminum sulfate, add them to 9.5kg of water and stir until completely dissolved; these will serve as initiators. Add 20kg of 28% hydrogen peroxide solution to the reactor, followed by 10kg of the initiator, and stir until thoroughly mixed. Adjust the pH of the system to 3–3.5 with sulfuric acid solution, then add 1mg of [amount missing]. 3 The wastewater from the production of Fumei Shuang was treated by maintaining the system temperature between 35℃ and 45℃ and stirring to ensure a reaction; then, 1m³ of the solution was added continuously. 3 The wastewater from the production of thiram was treated with the addition of 20 kg of hydrogen peroxide, and the pH value was monitored in real time to maintain it at 3-4, until the 3m³ of wastewater was treated. 3 After adding all the wastewater and continuing to stir the reaction for 0.5 hours, the system temperature was lowered to room temperature, centrifuged, and the wet product of thiram was obtained. After air drying, the product was weighed to obtain the dry product of thiram.

[0031] Example 3

[0032] This embodiment provides a deep recovery process for thiram production wastewater, treating 7m³ of thiram production wastewater. 3 The specific process is as follows:

[0033] Weigh out 350g of potassium persulfate and 650g of aluminum sulfate, respectively, and add them to 19kg of water, stirring until completely dissolved. Use this as an initiator. Add 20kg of 28% hydrogen peroxide to the reactor, then add 10kg of the initiator, stirring until thoroughly mixed. Adjust the pH of the system to 2-3 with sulfuric acid solution, then add 1mg of... 3 The wastewater from the production of Fumei Shuang was treated by maintaining the system temperature between 35℃ and 40℃ and stirring to ensure a reaction; then, 1m³ of the solution was added continuously. 3 The wastewater from the production of Fumei Shuang was treated with the addition of 20 kg of hydrogen peroxide until 3 m³ of the solution was completely added. 3 After treating the wastewater, add the remaining 10 kg of initiator and monitor the pH value in real time to maintain it at 2-3. Repeat this process every time 1 kg of initiator is added. 3 The wastewater from the production of thiram was treated by adding 20 kg of hydrogen peroxide while stirring to allow the reaction to proceed until the 7 m³ of the solution to be treated was reached. 3 After all the wastewater was added, the reaction was stirred for another 0.5 hours. The system temperature was then lowered to room temperature, centrifuged, and the wet product of thiram was obtained. After air drying, the product was weighed to obtain the dry product of thiram.

[0034] Example 4

[0035] This embodiment provides a deep recovery process for thiram production wastewater, treating 5m³ of thiram production wastewater. 3 The specific process is as follows:

[0036] Weigh out 500g of potassium persulfate and 500g of aluminum sulfate, add them to 10kg of water and stir until completely dissolved; these will serve as initiators. Add 100kg of 5% hydrogen peroxide solution to the reactor, then add 5.5kg of the initiator and stir until thoroughly mixed. Adjust the pH of the system to 1-1.5 with hydrochloric acid solution, then add 1mg of... 3 The wastewater from the production of Fumei Shuang was treated by maintaining the system temperature between 30℃ and 40℃ and stirring to ensure a reaction; then, 1m³ of the solution was added continuously. 3 The wastewater from the production of Fumei Shuang was treated by adding 100 kg of hydrogen peroxide until 2 m³ of the solution was completely dissolved. 3 After the wastewater is treated, the remaining initiator is added, and the pH value is monitored in real time to maintain it between 1 and 1.5. This process is repeated every 1 ml of initiator added. 3 The wastewater from the production of thiram was treated by adding 100 kg of hydrogen peroxide while stirring to allow the reaction to proceed until the 5 m³ of the wastewater to be treated was reached. 3 After all the wastewater was added and the mixture was stirred and reacted for 0.5 hours, the system temperature was lowered to room temperature, centrifuged, and the wet product of thiram was obtained. After air drying, the product was weighed to obtain the dry product of thiram.

[0037] Example 5

[0038] This embodiment provides a deep recovery process for thiram production wastewater, treating 8m³ of thiram production wastewater. 3 The specific process is as follows:

[0039] Weigh out 500g of potassium persulfate and 5kg of aluminum sulfate, add them to 100kg of water and stir until completely dissolved; this will serve as the initiator. Add 50kg of 20% hydrogen peroxide solution to the reactor, followed by 50kg of the initiator, and stir until thoroughly mixed. Adjust the pH of the system to 5-7 with nitric acid solution, then add 1mg of [amount missing]. 3 The wastewater from the production of Fumei Shuang was treated by maintaining the system temperature between 35℃ and 40℃ and stirring to ensure a reaction; then, 1m³ of the solution was added continuously. 3 The wastewater from the production of Fumei Shuang was treated with the addition of 50 kg of hydrogen peroxide until 4 m³ of the solution was completely added. 3 After the wastewater is treated, the remaining initiator is added, and the pH value is monitored in real time to maintain it at 5-7. This process is repeated every 1m³ of initiator added. 3 The wastewater from the production of thiram was treated by adding 50 kg of hydrogen peroxide while stirring to allow the reaction to proceed until the 8 m³ of the solution to be treated was reached. 3 After all the wastewater was added and the mixture was stirred and reacted for 1 hour, the system temperature was lowered to room temperature, centrifuged, and the wet product of thiram was obtained. After air drying, the product was weighed to obtain the dry product of thiram.

[0040] Examples 6-15

[0041] The deep recovery processes used in Examples 6 to 15 are the same as those provided in Example 3, and the wastewater treatment volume is also the same. The only difference is that the batches of the thiram production wastewater used are different.

[0042] Comparative Example 1

[0043] This comparative example provides a deep recovery process for thiram production wastewater, the specific process is as follows:

[0044] Weigh out 350g of potassium persulfate and 650g of aluminum sulfate, add them to 19kg of water and stir until completely dissolved; these will be used as initiators. Add 1m of [unclear text - possibly a reagent or solution] to the reaction vessel. 3 The wastewater from the production of thiram was treated with a sulfuric acid solution (same as in Example 1) to adjust the pH to 3-3.5. 20 kg of 28% hydrogen peroxide was added, followed by 10 kg of initiator. The system temperature was maintained between 35°C and 40°C, and the mixture was stirred to ensure complete reaction. Then, 1 kg of initiator was added each time. 3 The wastewater from the production of Fumei Shuang was treated with the addition of 20 kg of hydrogen peroxide until 3 m³ of the solution was completely added. 3 After the wastewater is treated, the remaining initiator is added, and the process is repeated for every 1m³ of initiator added. 3 The wastewater from the production of thiram was treated by adding 20 kg of hydrogen peroxide, while the pH was monitored in real time to maintain it at 3-3.5. The mixture was stirred to ensure a reaction, until the 7 m³ of wastewater to be treated was reached. 3 After all the wastewater was added and the mixture was stirred and reacted for 0.5 hours, the system temperature was lowered to room temperature, centrifuged, and the wet product of thiram was obtained. After air drying, the product was weighed to obtain the dry product of thiram.

[0045] Comparative Example 2

[0046] This comparative example provides a deep recovery process for thiram production wastewater, the specific process being:

[0047] Weigh out 350g of potassium persulfate and 650g of aluminum sulfate, add them to 19kg of water and stir until completely dissolved to prepare the initiator. Add 40% sulfuric acid solution and 20kg of 28% hydrogen peroxide to the reactor to adjust the pH to 3-3.5. Then add the prepared 20kg of initiator, and finally add 1ml of... 3 The wastewater from the production of Fumei Shuang was treated by maintaining the system temperature between 35℃ and 40℃ and stirring to ensure a complete reaction. Then, 1 ml of the solution was added continuously. 3 The wastewater from the production of Fumei Shuang was treated with the addition of 20 kg of hydrogen peroxide until 3 m³ of the solution was completely added. 3 After the wastewater is discharged, repeat the process of adding 1m³ of wastewater each time. 3 The wastewater from the production of thiram was treated by adding 20 kg of hydrogen peroxide, while the pH was monitored in real time to maintain it at 3-3.5. The mixture was stirred to ensure a reaction, until the 7 m³ of wastewater to be treated was reached. 3After all the wastewater was added and the mixture was stirred and reacted for 0.5 hours, the system temperature was lowered to room temperature, centrifuged, and the wet product of thiram was obtained. After air drying, the product was weighed to obtain the dry product of thiram.

[0048] Comparative Example 3

[0049] This comparative example provides a deep recovery process for thiram production wastewater, the specific process being:

[0050] Weigh out 350g of potassium persulfate and 650g of aluminum sulfate, add them to 19kg of water and stir until completely dissolved to prepare the initiator. Add 140kg of 28% hydrogen peroxide and 20kg of the prepared initiator to the reactor, stir until thoroughly mixed. Adjust the pH of the system to 3-3.5 with sulfuric acid solution, then add 7mg of... 3 The wastewater from the production of thiram was treated by controlling the system temperature between 35℃ and 40℃ and stirring for 0.5 hours to allow for a full reaction. After that, the system temperature was lowered to room temperature, centrifuged, and wet thiram was obtained. After air drying, the product was weighed to obtain dry thiram.

[0051] Test Example

[0052] The ammonia nitrogen and COD of the thiram production wastewater before and after treatment in Examples 1-15 and Comparative Examples 1-3 were detected, and the content of the dried thiram product was determined by liquid chromatography. The results are shown in Table 1.

[0053] Table 1

[0054]

[0055]

[0056]

[0057] As shown in Table 1, the amount of thiram product with a content greater than 80% can be recovered from each cubic meter of thiram production wastewater up to 12 kg. Based on this, it can be calculated that from approximately 3 cubic meters of thiram mother liquor produced for every ton of thiram production, 30-40 kg of thiram product can be recovered, resulting in considerable economic benefits. Specifically, in Examples 6-15, a total of 827 kg of dry thiram product was recovered, equivalent to approximately 706 kg of thiram at 100% concentration. This translates to an additional 36.6 kg of thiram recovered per ton of thiram produced (Examples 6-15 yielded a total deep recovery of 70 tons; assuming 1 ton of wastewater has a volume of 1 cubic meter). 3(Calculation) A total of 10 batches of thiram production wastewater were collected, and a total of 854 kg of thiram was recovered. According to statistics, each batch of thiram synthesis generates approximately 3.6 tons of production wastewater and 1.2 tons of thiram product. Therefore, the amount of thiram that can be recovered from the production wastewater per ton of thiram produced is 827 / 70*3.6 / 1.2 = 35.4 kg, with an average content of 85.4%, equivalent to 30.2 kg of thiram per 100% of its composition.

[0058] The above description is merely a preferred embodiment of the present invention, but the scope of protection of the present invention is not limited thereto. Any equivalent substitutions or modifications made by those skilled in the art within the scope of the technology disclosed in the present invention, based on the technical solution and inventive concept of the present invention, should be covered within the scope of protection of the present invention.

Claims

1. A deep recovery process for thiram production wastewater, characterized in that, include: Potassium persulfate and aluminum sulfate were dissolved in water to prepare an initiator for later use. Add 0.5–5 volumes of hydrogen peroxide and 0.5–5 volumes of the initiator sequentially into the reaction apparatus, mix well, and adjust the pH of the system to 1–7; Add 50-150 volumes of the thiram production wastewater to be treated to the reaction equipment, stir, and control the system temperature at 10℃-50℃; After the reaction was complete, the system temperature was restored to room temperature, and after centrifugation and drying, thiram and the treated wastewater were obtained.

2. The deep recovery process for the production wastewater of thiram as described in claim 1, characterized in that, After adding 50-150 volumes of the to-be-treated thiram production wastewater to the reaction equipment and stirring, the process further includes: Add 200-300 volumes of the thiram production wastewater to be treated in multiple batches, and add 0.5-5 volumes of hydrogen peroxide at the same time as adding 50-150 volumes of the thiram production wastewater.

3. The deep recovery process for the production wastewater of thiram as described in claim 2, characterized in that, After the step of adding 200-300 volumes of the thiram production wastewater to be treated in multiple batches, and simultaneously adding 0.5-5 volumes of hydrogen peroxide every 50-150 volumes of the thiram production wastewater, the method further includes: Add 0.5 to 5 volumes of the initiator to the reaction equipment, and then add 200 to 400 volumes of the thiram production wastewater to be treated in multiple batches. Add 0.5 to 5 volumes of hydrogen peroxide at the same time as adding 50 to 150 volumes of the thiram production wastewater to be treated.

4. The deep recovery process for the production wastewater of thiram as described in claim 1, characterized in that, In the initiator, the mass ratio of potassium persulfate to aluminum sulfate is 1:1 to 10.

5. The deep recovery process for the production wastewater of Fumei Shuang as described in claim 1, characterized in that, In the initiator, the concentration of potassium persulfate is 5-50 g / L, and the concentration of aluminum sulfate is 30-50 g / L.

6. The deep recovery process for the production wastewater of Fumei Shuang as described in claim 1, characterized in that, In steps 1 to 7, the pH of the system is adjusted using an aqueous solution of sulfuric acid, hydrochloric acid, or nitric acid.

7. The deep recovery process for the production wastewater of thiram as described in claim 1, characterized in that, The concentration of hydrogen peroxide is 5% to 30%.

8. The deep recovery process for the production wastewater of thiram as described in claim 2, characterized in that, The volume ratio of hydrogen peroxide added to the thiram production wastewater in each batch is 1-10:

200.

9. The deep recovery process for the production wastewater of thiram as described in claim 1, characterized in that, The system temperature is controlled to be between 35℃ and 40℃ throughout the reaction process.

10. The deep recovery process for thiram production wastewater as described in any one of claims 1 to 9, characterized in that, The thiram production wastewater is the thiram mother liquor produced during the preparation of thiram using the hydrogen peroxide method.

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