Deep recovery process of thiram production wastewater

Abstract

The invention belongs to the technical field of wastewater treatment, and particularly relates to a deep recovery process of thiram production wastewater. The preparation method comprises the following specific steps: dissolving potassium persulfate and aluminum sulfate in water to prepare an initiator for later use; sequentially adding 0.5-5 volume of hydrogen peroxide and 0.5-5 volume of the initiator into the reaction equipment, uniformly mixing, and adjusting the pH value of the system to 1-7; adding 50-150 volume of the thiram production wastewater to be treated into the reaction equipment, stirring, and controlling the temperature of the system to be 10-50 DEG C; and after the reaction is finished, recovering the temperature of the system to room temperature, and centrifuging and drying to obtain thiram and treated wastewater. According to the method disclosed by the invention, the thiram active compound is obtained from the thiram production wastewater, the COD (Chemical Oxygen Demand) content and the ammonia nitrogen content in the wastewater are simultaneously reduced, the COD of the wastewater can be reduced to 5000mg / L or below, the reduction amplitude of the ammonia nitrogen content is close to 93% at most, and the subsequent treatment difficulty is reduced.

Description

Technical Field

[0001] The invention belongs to the technical field of wastewater treatment, and specifically relates to a deep recovery process of thiram production wastewater. Background Art

[0002] Thiram, molecular formula is C6H 12 N2S4, also known as tetramethylthiuram disulfide, is a vulcanization accelerator, bactericide and seed soaking agent widely used in industry and agriculture. The traditional preparation method of thiram is chlorine-air method, but the method will produce a large amount of waste gas, waste water and waste salt, not only causing great pollution to the environment, but also raising the production cost, and the process safety is low. The applicant has provided a kind of efficient green synthesis method of thiram (CN106699622 A) through a large number of experimental studies. Compared with the traditional chlorine oxidation method, the hydrogen peroxide oxidation method of thiram production method not only avoids the use of highly toxic chemicals chlorine, greatly reducing the safety risk of production, but also merges the original sodium thiram synthesis and chlorine oxidation two processes into one process, cancels the consumption of sodium hydroxide solution in the intermediate process, simplifies the production process, and enhances operational safety. From the perspective of environmental protection, the amount of waste water produced by the traditional chlorine oxidation method to produce one ton of thiram is more than 10 tons, while the amount of waste water produced by the hydrogen peroxide oxidation method to produce one ton of thiram drops to 3 tons, greatly reducing the pressure on environmental protection.

[0003] However, the COD concentration in the wastewater generated by the production of thiram is generally as high as 15,000 to 20,000 mg / L, which increases the difficulty of subsequent treatment. The main components of the wastewater are thiram and carbon disulfide partially dissolved in the water. Due to the low concentration of thiram and the inability to continue to generate thiram under normal synthesis conditions, it can only be treated together with other production wastewater through subsequent conventional sewage treatment processes and discharged after meeting the emission 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, which can not only extract valuable thiram technical from the thiram production wastewater again, but also reduce the COD of the wastewater to below 5000 mg / L, and the reduction of ammonia nitrogen content is as high as nearly 93%, thereby reducing the difficulty of subsequent treatment of the wastewater.

[0005] In order to solve the above technical problems, the present invention provides a deep recovery process of thiram production wastewater, comprising:

[0006] Dissolve potassium persulfate and aluminum sulfate in water to prepare an initiator for later use;

[0007] Add 0.5 to 5 volumes of hydrogen peroxide and 0.5 to 5 volumes of the initiator into the reaction device in sequence, mix well, and adjust the pH value of the system to 1 to 7;

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

[0009] After the reaction is completed, the system temperature is restored to room temperature, and the product is centrifuged and dried to obtain thiram and treated waste water.

[0010] The deep recovery process of thiram production wastewater provided by the present invention comprises the following steps: firstly, potassium persulfate and aluminum sulfate are dissolved in water to prepare an initiator, and then various reagents (hydrogen peroxide-initiator-pH adjustment system) are added in a specific order and proportion; under the condition of pH of 1 to 7, an aqueous hydrogen peroxide solution is used as an oxidant, and potassium persulfate and aluminum sulfate are used as initiators, and together with the oxidant, effective materials (mainly unreacted raw materials and generated intermediates) in the thiram mother liquor are promoted to continue to generate thiram, thereby realizing the recovery and utilization of potential thiram in the thiram production wastewater.

[0011] In combination with the first aspect, after the step of adding 50 to 150 volumes of the to-be-treated thiram production wastewater to the reaction equipment and stirring, the method further includes the step of adding 200 to 300 volumes of the to-be-treated thiram production wastewater in multiple times, and adding 0.5 to 5 volumes of hydrogen peroxide every time 50 to 150 volumes of the to-be-treated thiram production wastewater are added.

[0012] In combination with the first aspect, after the step of adding 200 to 300 volumes of the to-be-treated thiram production wastewater in multiple times, and supplementing 0.5 to 5 volumes of hydrogen peroxide when 50 to 150 volumes of the to-be-treated thiram production wastewater are added, the method further includes the steps of adding 0.5 to 5 volumes of the initiator to the reaction device, and then adding 200 to 400 volumes of the to-be-treated thiram production wastewater in multiple times, and supplementing 0.5 to 5 volumes of hydrogen peroxide when 50 to 150 volumes of the to-be-treated thiram production wastewater are added.

[0013] In practical applications, a suitable recovery process can be selected in combination with the actual situation and the amount of thiram production wastewater to be treated. When the total amount to be treated is large, the thiram production wastewater to be treated is added in batches and accompanied by the addition of hydrogen peroxide, which can make the reaction more sufficient, thereby improving the recovery rate of thiram in the thiram production wastewater.

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

[0015] In combination with the first aspect, in the initiator, the concentration of potassium persulfate is 5 to 50 g / L, and the concentration of aluminum sulfate is 30 to 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 combination with the first aspect, in the step of adjusting the pH value of the system to 1 to 7, the pH is adjusted with 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 actual conditions. For example, when the alkalinity of the system is strong, an acidic solution with a higher concentration can be used for adjustment. When the pH value of the system is close to the expected value, an acidic solution with a lower concentration can be used for fine-tuning.

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

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

[0020] In combination with the first aspect, the system temperature is always controlled between 35° C. and 40° C. during the reaction. Since the reaction is an exothermic reaction and the starting temperature is low, it is generally not necessary to take special measures to increase the system temperature. The system temperature can be controlled by combining the heat release of the reaction itself and the jacket cooling water.

[0021] In conjunction with the first aspect, the thiram production wastewater is the thiram mother liquor produced when thiram is prepared according to the hydrogen peroxide oxidation method. The hydrogen peroxide oxidation method is an efficient green synthesis method without an organic solvent, and the purity of the obtained thiram can reach more than 98% (see CN 106699622 A). However, the thiram mother liquor produced by the method is directly processed and discharged after passing the test, which causes a waste of resources to a certain extent.

[0022] The beneficial effects obtained by the present invention are as follows: the deep recovery process of the wastewater produced by the thiram provided by the present invention takes energy saving and consumption reduction and turning waste into treasure as the starting point, uses a specific initiator to perform secondary synthesis on the raw materials remaining in the mother liquor generated when the thiram is synthesized by the hydrogen peroxide oxidation method, and realizes deep recovery, not only a certain amount of thiram technical drug is obtained from the thiram mother liquor (the amount of thiram product with a content of more than 80% recovered per cubic meter of thiram production wastewater can reach more than 10kg), but also the chemical oxygen demand (COD) in the thiram mother liquor can be reduced to less than 5000mg / L, and the reduction of ammonia nitrogen is as high as nearly 93%, so that the difficulty of subsequent treatment of the wastewater produced by the thiram is greatly reduced. DETAILED DESCRIPTION

[0023] In order to make the purpose, technical solution and advantages of the present invention more clearly understood, the present invention is further described in detail below in conjunction with specific embodiments. It should be understood that the specific embodiments described herein are only used to explain the present invention and are not used to limit the present invention.

[0024] The thiram production wastewater used in the following examples and comparative examples is wastewater produced by hydrogen peroxide oxidation method (CN106699622 A) (i.e., the filtrate obtained after filtration - thiram mother liquor). In addition, the volume of the reactor used in the following examples and comparative examples is 10m 3 The volume of wastewater treated is 1 to 8 m 3 Among them, Examples 1 to 5 and Comparative Examples 1 to 3 all use the same batch of thiram production wastewater, and Example 1 and Examples 6 to 15 use different batches of thiram production wastewater. In practical applications, a larger volume of reactor 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 to treat 1m 3 , the specific process is:

[0027] Weigh 55g of potassium persulfate and 105g of aluminum sulfate respectively, add them into 3kg of water and stir until they are completely dissolved as initiators. Add 5kg of hydrogen peroxide with a concentration of 28% into the reactor, then add 1.58kg of initiator and stir to mix thoroughly. Use sulfuric acid solution to adjust the system pH to 3-3.5, then add 0.2m 3 The temperature of the system is always controlled between 35℃ and 40℃ for the wastewater produced by Fumei. 3 Thiram production wastewater, add 5kg hydrogen peroxide until 0.6m 3 After the wastewater, add the remaining 1.58 kg of initiator, and monitor the pH value in real time to maintain it at 3-3.5, and repeat every time 0.2 m 3 Thiram production wastewater, add 5kg hydrogen peroxide, and stir to react until 1m 3 After all the wastewater has been added, the reaction is continued with stirring for 0.5 h, the system temperature is lowered to room temperature, centrifuged to obtain the wet product of thimerosal, and then air-dried and weighed to obtain the dry product of thimerosal.

[0028] Example 2

[0029] This embodiment provides a deep recovery process for thiram production wastewater to treat 3m 3 , the specific process is:

[0030] Weigh 175g potassium persulfate and 325g aluminum sulfate respectively, add to 9.5kg water and stir until completely dissolved, as initiator. Add 20kg hydrogen peroxide with a concentration of 28% into the reactor, then add 10kg initiator, stir to mix thoroughly. Use sulfuric acid solution to adjust the system pH to 3-3.5, then add 1m 3 The wastewater produced by Thiram is kept at a temperature between 35℃ and 45℃, and stirred to make it react; then 1m 3 Thiram production wastewater, along with the addition of 20kg hydrogen peroxide, and real-time monitoring of the pH value to maintain it at 3-4, until 3m 3 After all the wastewater is added, the reaction is continued with stirring for 0.5 h, the system temperature is lowered to room temperature, centrifuged to obtain the wet product of thimerosal, and then air flow dried and weighed to obtain the dry product of thimerosal.

[0031] Example 3

[0032] This embodiment provides a deep recovery process for thiram production wastewater to treat 7m3 of thiram production wastewater. 3 , the specific process is:

[0033] Weigh 350g of potassium persulfate and 650g of aluminum sulfate respectively, add them into 19kg of water and stir until they are completely dissolved as initiators. Add 20kg of 28% hydrogen peroxide into the reactor, then add 10kg of initiator and stir to mix thoroughly. Use sulfuric acid solution to adjust the system pH to 2-3, then add 1m 3 The wastewater produced by Thiram is kept at a temperature between 35℃ and 40℃, and stirred to make it react; then continue to add 1m 3 Thiram production wastewater, add 20kg hydrogen peroxide until 3m 3 After the wastewater is discharged, the remaining 10 kg of initiator is added, and the pH value is monitored in real time to maintain it at 2-3. Repeat this process every time 1 m 3 Thiram production wastewater, add 20kg hydrogen peroxide, and stir to react until 7m3 of wastewater to be treated 3 After all the wastewater has been added, the reaction is continued with stirring for 0.5 h, the system temperature is lowered to room temperature, centrifuged to obtain the wet product of thimerosal, and then air-dried and weighed to obtain the dry product of thimerosal.

[0034] Example 4

[0035] This embodiment provides a deep recovery process for thiram production wastewater to treat 5m3 of thiram production wastewater. 3 , the specific process is:

[0036] Weigh 500g of potassium persulfate and 500g of aluminum sulfate respectively, add them into 10kg of water and stir until they are completely dissolved as initiators. Add 100kg of 5% hydrogen peroxide into the reactor, then add 5.5kg of initiator and stir to mix thoroughly. Use hydrochloric acid solution to adjust the system pH to 1-1.5, then add 1m 3 Furamide production wastewater, control the system temperature to always be between 30℃ and 40℃, stir to make it react; then continue to add 1m 3 Thiram production wastewater, add 100kg hydrogen peroxide until 2m 3 After the wastewater is added, the remaining initiator is added, and the pH value is monitored in real time to maintain it at 1-1.5. Repeat this process every time 1m 3 Thiram production wastewater, add 100kg hydrogen peroxide, and stir to react until 5m3 of wastewater to be treated 3 After all the wastewater is added, the reaction is stirred for 0.5 h, and then the system temperature is lowered to room temperature, centrifuged to obtain the wet product of thimerosal, and then air-dried and weighed to obtain the dry product of thimerosal.

[0037] Example 5

[0038] This embodiment provides a deep recovery process for thiram production wastewater to treat 8m3 of thiram production wastewater. 3 , the specific process is:

[0039] Weigh 500g of potassium persulfate and 5kg of aluminum sulfate respectively, add them into 100kg of water and stir until they are completely dissolved as initiators. Add 50kg of 20% hydrogen peroxide into the reactor, then add 50kg of initiator and stir to mix thoroughly. Use nitric acid solution to adjust the system pH to 5-7, then add 1m 3 The wastewater produced by Thiram is kept at a temperature between 35℃ and 40℃, and stirred to make it react; then continue to add 1m 3 Thiram production wastewater, add 50kg hydrogen peroxide until 4m 3 After the wastewater is added, the remaining initiator is added, and the pH value is monitored in real time to maintain it at 5-7. Repeat this process every time 1m 3 Thiram production wastewater, add 50kg hydrogen peroxide, and stir to react until 8m3 of wastewater to be treated 3 After all the wastewater is added, the reaction is stirred for 1 hour, and then the system temperature is lowered to room temperature, centrifuged to obtain the wet product of thiram, and then air-dried and weighed to obtain the dry product of thiram.

[0040] Embodiments 6 to 15

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

[0042] Comparative Example 1

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

[0044] Weigh 350g of potassium persulfate and 650g of aluminum sulfate respectively, add them into 19kg of water and stir until they are completely dissolved as initiators. 3 Thiram production wastewater was adjusted to pH 3-3.5 with the same sulfuric acid solution as in Example 1, 20 kg of hydrogen peroxide with a concentration of 28% was added, and then 10 kg of initiator was added. The system temperature was always controlled between 35°C and 40°C, and stirred to allow sufficient reaction; and then 1 m 3 Thiram production wastewater, add 20kg hydrogen peroxide until 3m 3 After the wastewater, add the remaining initiator, and repeat the process of adding 1m 3 Thiram production wastewater, along with the addition of 20kg hydrogen peroxide, and real-time monitoring of pH to maintain it at 3-3.5, while stirring to react until the 7m to be treated 3 After all the wastewater is added, the reaction is stirred for 0.5 h, and then the system temperature is lowered to room temperature, centrifuged to obtain the wet product of thimerosal, and then air-dried and weighed to obtain the dry product of thimerosal.

[0045] Comparative Example 2

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

[0047] Weigh 350g of potassium persulfate and 650g of aluminum sulfate respectively, add them into 19kg of water and stir until they are completely dissolved as initiators. Add 40% sulfuric acid solution and 20kg of 28% hydrogen peroxide into the reactor to adjust the system pH to 3-3.5, then add 20kg of the prepared initiator, and finally add 1m 3 Furamide production wastewater, control the system temperature always between 35 ℃ ~ 40 ℃, stir to make it fully react; then continue to add 1m 3 Thiram production wastewater, add 20kg hydrogen peroxide until 3m 3 After the wastewater, repeat the process of adding 1m 3 Thiram production wastewater, along with the addition of 20kg hydrogen peroxide, and real-time monitoring of pH to maintain it at 3-3.5, while stirring to react until the 7m to be treated 3After all the wastewater is added, the reaction is stirred for 0.5 h, and then the system temperature is lowered to room temperature, centrifuged to obtain the wet product of thimerosal, and then air-dried and weighed to obtain the dry product of thimerosal.

[0048] Comparative Example 3

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

[0050] Weigh 350g of potassium persulfate and 650g of aluminum sulfate respectively, add them into 19kg of water and stir until they are completely dissolved as initiators. Add 140kg of 28% hydrogen peroxide and 20kg of the prepared initiator into the reactor and stir to mix them thoroughly. Use sulfuric acid solution to adjust the system pH to 3-3.5, then add 7m 3 For the wastewater produced by thiram, the system temperature was controlled to be always between 35℃ and 40℃, and it was stirred for 0.5h to allow sufficient reaction. Then the system temperature was lowered to room temperature and centrifuged to obtain wet thiram. After air drying, it 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 to 15 and Comparative Examples 1 to 3 were respectively detected, and the content of the obtained thiram dry 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 products with a content of more than 80% per cubic meter of thiram production wastewater can reach 12kg. According to this calculation, 30-40kg of thiram products can be recovered from about 3 cubic meters of thiram mother liquor produced by producing one ton of thiram, which has considerable economic benefits. Specifically, according to the above embodiments 6-15, a total of 827kg of dry thiram products are recovered, which is equivalent to about 706kg of thiram per 100 tonnes of thiram, which is equivalent to 36.6kg more thiram per ton of thiram production (70 tons of thiram are recovered in total in embodiments 6-15 (according to the volume of 1 ton of wastewater as 1m 3Calculation) Thiram production wastewater, a total of 10 batches, recovered Thiram totaling 854kg. According to statistics, each batch of Thiram synthesis produces about 3.6t of production wastewater and 1.2t of Thiram finished product, equivalent to the amount of Thiram that can be recovered from the production wastewater per ton of Thiram production is 827 / 70*3.6 / 1.2=35.4kg, with an average content of 85.4%, equivalent to 30.2kg of Thiram).

[0058] What is described above is only a preferred specific implementation manner of the present invention, but the protection scope of the present invention is not limited thereto. Any technician familiar with the technical field can make equivalent replacements or changes according to the technical scheme and inventive concept of the present invention within the technical scope disclosed by the present invention, which should be covered by the protection scope of the present invention.

Claims

1. A deep recovery process for thiram production wastewater, characterized in that: include: Dissolve potassium persulfate and aluminum sulfate in water to prepare an initiator for later use; Add 0.5 to 5 volumes of hydrogen peroxide and 0.5 to 5 volumes of the initiator into the reaction device in sequence, mix well, and adjust the pH value of the system to 1 to 7; Add 50 to 150 volumes of the to-be-treated thiram production wastewater into the reaction equipment, stir, and control the system temperature to 10° C. to 50° C.; After the reaction is completed, the system temperature is restored to room temperature, and the product is centrifuged and dried to obtain thiram and treated waste water.

2. The deep recovery process of thiram production wastewater as claimed in claim 1, characterized in that: After adding 50 to 150 volumes of the to-be-treated thiram production wastewater to the reaction device and stirring, the step further comprises: 200 to 300 volumes of thiram production wastewater to be treated are added in several times, and 0.5 to 5 volumes of hydrogen peroxide are added when 50 to 150 volumes of thiram production wastewater to be treated are added.

3. The deep recovery process of thiram production wastewater as claimed in claim 2, characterized in that: After the step of adding 200 to 300 volumes of the to-be-treated thiram production wastewater in multiple times and adding 0.5 to 5 volumes of hydrogen peroxide every time 50 to 150 volumes of the to-be-treated thiram production wastewater are added, the method further comprises: 0.5 to 5 volumes of the initiator are added to the reaction device, and then 200 to 400 volumes of the thiram production wastewater to be treated are added in multiple times, and 0.5 to 5 volumes of hydrogen peroxide are added when 50 to 150 volumes of the thiram production wastewater to be treated are added.

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

5. The deep recovery process of thiram production wastewater as claimed in claim 1, characterized in that: In the initiator, the concentration of potassium persulfate is 5 to 50 g / L, and the concentration of aluminum sulfate is 30 to 50 g / L.

6. The deep recovery process of thiram production wastewater according to claim 1, characterized in that: In the step of adjusting the pH value of the system to 1-7, the pH is adjusted with an aqueous solution of sulfuric acid, hydrochloric acid or nitric acid.

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

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

200.

9. The deep recovery process of thiram production wastewater according to claim 1, characterized in that: During the reaction process, the system temperature is always controlled between 35°C and 40°C.

10. The deep recovery process of thiram production wastewater according to any one of claims 1 to 9, characterized in that: The thiram production wastewater is the thiram mother liquor generated when thiram is prepared by hydrogen peroxide oxidation method.

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