Method and system for resourceful treatment of nitropyrazole mixed acid waste liquid

Abstract

The invention discloses a method and system for resourceful treatment of nitropyrazole mixed acid waste liquid, and belongs to the technical field of waste water resourceful treatment. The method for resourceful treatment of the nitropyrazole mixed acid waste liquid comprises a method for treating pyrazole and N-nitropyrazole in N-nitration waste acid by adopting an advanced oxidation technology and a method for recovering 3, 4-dinitropyrazole and sulfuric acid from C-nitration process waste liquid. According to the method, an advanced oxidation technology is adopted in the process of treating the N-nitration waste acid solution, an oxidizing agent is not needed, and effective degradation of pyrazole and N-nitropyrazole can be realized by utilizing an acetic acid solution in the wastewater and additional scrap iron; in the C-nitration process, the extraction method using the extractant effectively reduces the cost, the operation is simple, the risk of DNP explosion caused by high-temperature heating is avoided, the extraction recovery rate of DNP reaches 99.8%, the concentration of recovered sulfuric acid reaches 97%, and the COD content is lower than 100 mg / L.

Description

Technical Field

[0001] The present invention relates to the technical field of wastewater resource treatment, and in particular to a method and system for resource treatment of nitropyrazole mixed acid waste liquid. Background Art

[0002] Nitropyrazole compounds are important chemical raw materials, and a large amount of wastewater is inevitably generated during their synthesis and refining process. The synthesis of 3,4-dinitropyrazole (DNP) usually adopts a three-step synthesis method, using pyrazole as the raw material, and obtaining the product N-nitropyrazole through nitric acid nitration (N-nitration), and then obtaining 3,4-dinitropyrazole through rearrangement and C-nitration. Since a series of mixed acid reaction systems such as acetic acid, nitric acid and sulfuric acid are required in its synthesis process, the wastewater produced is highly acidic. At the same time, there are nitro compounds such as pyrazole, N-nitropyrazole, 3-nitropyrazole, and 3,4-dinitropyrazole in the wastewater. These wastewaters containing a large amount of acidic nitro compounds cannot be biodegraded after entering the environment. If not handled properly, they will seriously harm the ecological environment.

[0003] Traditional industrial treatment methods generally use a combination of stripping, thermal decomposition and ammonia distillation to improve the biodegradability of wastewater. However, during the treatment process, the wastewater contains a large amount of nitro compounds such as pyrazole, N-nitropyrazole, 3-nitropyrazole, 3,4-dinitropyrazole, etc., and high-temperature heating will have certain safety hazards. In addition, this method requires the equipment to be resistant to high temperatures and corrosion, which greatly increases the treatment cost. Summary of the invention

[0004] In order to solve the deficiencies in the prior art, the present invention provides a treatment process for recovering DNP and sulfuric acid from nitric-sulfuric acid mixed acid wastewater, and uses advanced oxidation technology to effectively degrade nitro compounds in water bodies to achieve standard discharge.

[0005] The present invention adopts the following technical solution.

[0006] The first aspect of the present invention discloses a method for resource-based treatment of nitropyrazole mixed acid waste liquid, comprising advanced oxidation treatment of pyrazole and N-nitropyrazole in N-nitration waste acid and recovery of 3,4-dinitropyrazole and sulfuric acid from C-nitration process waste liquid;

[0007] The method of treating pyrazole and N-nitropyrazole in N-nitration waste acid by advanced oxidation comprises taking N-nitration waste acid solution, mixing with a set amount of iron filings, and shaking at a constant temperature under set conditions to obtain a waste liquid after degrading pyrazole and N-nitropyrazole;

[0008] The method of recovering 3,4-dinitropyrazole and sulfuric acid from the waste liquid of the C-nitration process comprises using an extractant to recover 3,4-dinitropyrazole in the C-nitration process and using a distillation method to recover sulfuric acid in the C-nitration process.

[0009] Preferably, the N-nitration waste acid solution is prepared by diluting an N-nitration waste water solution and placing the diluted waste water solution in a reaction container.

[0010] Preferably, the set amount of iron filings is 0.01 g to 0.1 g of iron filings added to the reaction container.

[0011] Preferably, the set conditions are to place the reaction container in a water bath constant temperature oscillator for oscillation at room temperature and 0-300 rpm for 0-300 min.

[0012] Preferably, the method for recovering 3,4-dinitropyrazole and sulfuric acid from C-nitration process waste liquid comprises:

[0013] Place the C-nitration process waste liquid and the extractant in a separatory funnel in proportion and mix thoroughly, shake well and let stand to obtain a solution with a clear interface between the two phases;

[0014] Open the lid of the separatory funnel and turn the knob to separate the two phases;

[0015] The separated extract is placed in a vacuum distillation apparatus, and rotary distilled under set conditions to recover 3,4-dinitropyrazole;

[0016] The mother liquor separated above is taken and placed in a distillation tower, the distillation temperature is adjusted, and sulfuric acid is recovered.

[0017] Preferably, the content of 3,4-dinitropyrazole in the C-nitration process waste liquid is not less than 3.95%, and the extractant is ethyl acetate.

[0018] Preferably, the set conditions for rotary evaporation are to adjust the vacuum degree to -0.1 MPa and perform rotary evaporation at 80°C.

[0019] Preferably, during the distillation process, the tower kettle and the distillation tower are heated at normal pressure, and the temperatures of the tower kettle and the upper and lower sections of the distillation tower are always kept the same. The temperature of each heating point is gradually increased from 80°C, by 10°C each time, and each temperature is maintained for more than half an hour.

[0020] Preferably, during the distillation process, when a fraction is generated, total reflux is maintained for 10 minutes and then the fraction is collected at a reflux ratio of 1:1.

[0021] The second aspect of the present invention discloses a system for recycling nitropyrazole mixed acid waste liquid, and the method for recycling nitropyrazole mixed acid waste liquid comprises: a mixing module, an extraction module, a rotary evaporation module and a distillation module;

[0022] The mixing module includes a conical flask and a water bath constant temperature oscillator, which is used to degrade pyrazole and N-nitropyrazole in N-nitration waste acid;

[0023] The extraction module includes a separatory funnel for separating 3,4-dinitropyrazole and sulfuric acid;

[0024] The rotary evaporation module includes a vacuum distillation device for rotary evaporation to recover 3,4-dinitropyrazole;

[0025] The distillation module comprises a tower kettle and a distillation tower, and is used for distilling and recovering sulfuric acid.

[0026] Compared with the prior art, the beneficial effects of the present invention include at least:

[0027] The present invention adopts advanced oxidation technology in the process of treating N-nitration waste acid solution, without oxidant, and utilizes the acetic acid solution in the wastewater and the added iron filings to achieve effective degradation of pyrazole and N-nitropyrazole; in the C-nitration process, compared with the traditional high-temperature heating process, the extraction method using an extractant can effectively reduce costs, is simple to operate, avoids the risk of 3,4-dinitropyrazole explosion caused by high-temperature heating, and the extraction recovery rate of 3,4-dinitropyrazole reaches 99.8%. The method of the present invention realizes the separation of nitric acid and sulfuric acid in the mother liquor after extraction, and recycles sulfuric acid, the concentration of sulfuric acid after recovery reaches 97%, and the COD content is less than 100mg / L. BRIEF DESCRIPTION OF THE DRAWINGS

[0028] Figure 1 The degradation performance of nitro compounds with different iron filing dosages;

[0029] Figure 2 is the extraction performance of different extractants;

[0030] Figure 3 It is the effect of ethyl acetate extraction ratio;

[0031] Figure 4 is the effect of the number of ethyl acetate extractions;

[0032] Figure 5 are (a) extract and mother liquor; (b) recovered 3,4-dinitropyrazole;

[0033] Figure 6 It is the change of sulfuric acid content and COD in high temperature oxidation degradation solution;

[0034] Figure 7 It is the change in the content of nitric acid in the high-temperature oxidative degradation solution. DETAILED DESCRIPTION

[0035] In order to make the purpose, technical scheme and advantages of the present invention clearer, the technical scheme of the present invention will be clearly and completely described below in conjunction with the drawings in the embodiments of the present invention. The embodiments described in this application are only embodiments of a part of the present invention, rather than all embodiments. Based on the spirit of the present invention, all other embodiments obtained by ordinary technicians in this field without making creative work belong to the protection scope of the present invention.

[0036] In recent years, my country has actively promoted the clean substitution of fuel raw materials, emphasized the clean and low-carbon transformation of key industries, and promoted the clean production of process flows. Among them, wastewater reuse is an important means of water conservation and emission reduction. The recycling of nitropyrazole compounds in wastewater can also create value for enterprises. The recycling of 3,4-dinitropyrazole and sulfuric acid in wastewater has obvious economic and environmental benefits. At the same time, the use of advanced oxidation technology can effectively treat the remaining tail water of other nitro compounds to achieve standard discharge.

[0037] The embodiment of the present invention provides a method for resource-based treatment of nitropyrazole mixed acid waste liquid, comprising using advanced oxidation technology to treat pyrazole and N-nitropyrazole in N-nitration waste acid and recovering 3,4-dinitropyrazole and sulfuric acid from C-nitration process waste liquid.

[0038] The method for treating pyrazole and N-nitropyrazole in N-nitration waste acid by using advanced oxidation technology comprises the following steps:

[0039] Step 1: After the N-nitration wastewater solution is diluted 100 times, 50 mL of the solution is taken into a 250 mL conical flask, and 0.01 g to 0.1 g of iron filings are quickly added into the conical flask.

[0040] Step 2, placing the conical flask in a water bath constant temperature oscillator for shaking at room temperature and 0-300 rpm, reacting for 0-300 min, and obtaining a waste liquid after degrading pyrazole and N-nitropyrazole.

[0041] Preferably, the conical flask is placed in a water bath constant temperature oscillator at 25°C and 200 rpm for 300 min. Figure 1 As shown, (a) is the degradation effect of 1-nitropyrazole under different iron filings addition conditions; (b) is the degradation kinetic fitting result of 1-nitropyrazole under different iron filings addition conditions.

[0042] The method for recovering 3,4-dinitropyrazole and sulfuric acid from C-nitration process waste liquid comprises the following steps:

[0043] Step A, placing the C-nitration process waste liquid and the extractant in a separatory funnel in a set ratio and mixing them thoroughly, shaking them well and letting them stand to obtain a solution with a clear interface between the two phases;

[0044] The content of 3,4-dinitropyrazole in the C-nitration process waste liquid is not less than 3.95%.

[0045] The extractant is ethyl acetate.

[0046] The volume ratio of the waste liquid to the extractant liquid is 1:1. It is worth noting that when ethyl acetate is used as the extractant, the extraction effect increases as the volume of ethyl acetate increases.

[0047] Step B, open the cover of the separatory funnel and turn the knob to separate the two phases;

[0048] Step C, taking the above separated extract, placing it in a vacuum distillation apparatus, and performing rotary distillation under set conditions to obtain 3,4-dinitropyrazole.

[0049] The conditions set in step C are to adjust the vacuum degree to -0.1 MPa and perform rotary evaporation at 80°C.

[0050] Step D, taking the separated mother liquor, placing it in a distillation tower, adjusting the distillation temperature, and recovering sulfuric acid.

[0051] In the step D, the tower bottom and the distillation tower are heated at normal pressure. During the distillation process, the tower bottom and the upper and lower sections of the distillation tower are always kept at the same temperature. The temperature of each heating point is gradually increased from 80°C. To maintain a stable state, the temperature is increased by 10°C each time, and each temperature is maintained for more than half an hour. When a distillate is generated, the distillate is collected at a reflux ratio of 1:1 after maintaining full reflux for 10 minutes.

[0052] Embodiment 1:

[0053] The wastewater obtained by C-nitration reaction in the production process of 3,4-dinitropyrazole has the following physical and chemical properties: pH = 1, 3,4-dinitropyrazole content is about 3.95%, H2SO4 content is about 29.1%, HNO3 content is about 3.3%, and the waste liquid is mixed with ethyl acetate / toluene / chloroform / carbon tetrachloride as extractants in a volume ratio of 1:1 and shaken. After standing, when the interface between the two phases is clear, open the cover of the separatory funnel and turn the knob to separate the two phases, and calculate the 3,4-dinitropyrazole content in the two phases. Figure 2 As shown, with ethyl acetate / chloroform / carbon tetrachloride / toluene as the extracting agent, the extraction rates of 3,4-dinitropyrazole, i.e., the extraction effects, are 87.1%, 1.4%, 23.9% and 4.9% respectively.

[0054] When ethyl acetate is used as the extractant, the separated extract is placed in a reduced pressure distillation apparatus, the vacuum degree in the reactor is adjusted to -0.1 MPa, and rotary evaporation is performed at 80°C. After all the liquid is evaporated, 3,4-dinitropyrazole solid is obtained, and the recovery rate reaches 95.5%.

[0055] When ethyl acetate is used as the extractant, the separated mother liquor is placed in a distillation tower, and the tower bottom and the distillation tower are heated at normal pressure. During the distillation process, the tower bottom and the upper and lower sections of the distillation tower are always kept at the same temperature. The temperature of each heating point is gradually increased from 80°C. To maintain a stable state, the temperature is increased by 10°C each time, and each temperature is maintained for more than half an hour. When a distillate is produced, the distillate is taken at a reflux ratio of 1:1 after maintaining full reflux for 10 minutes. The temperature is heated to 240°C to obtain recovered sulfuric acid, and the concentration of sulfuric acid finally reaches more than 97%.

[0056] Embodiment 2:

[0057] The wastewater obtained by C-nitration reaction in the production process of 3,4-dinitropyrazole has the following physical and chemical properties: pH = 1, 3,4-dinitropyrazole content is about 3.95%, H2SO4 content is about 29.1%, HNO3 content is about 3.3%, and the waste liquid is mixed with ethyl acetate as an extractant in a volume ratio of 5:1, 3:1, 1:1, 1:3, and 1:5, and shaken well. After standing, when the interface between the two phases is clear, open the cover of the separatory funnel and turn the knob to separate the two phases, and calculate the 3,4-dinitropyrazole content in the two phases. Figure 3 As shown, when ethyl acetate is used as the extractant, the extraction effect increases with the increase of the volume of ethyl acetate, which are 25.9%, 68.6%, 80.4%, 86.8% and 94.7% respectively.

[0058] The separated extract was placed in a reduced pressure distillation apparatus, the vacuum degree in the reactor was adjusted to -0.1 MPa, and rotary distillation was performed at 80°C. After all the liquid was distilled out, 3,4-dinitropyrazole solid was obtained, and the recovery rate could reach 96%.

[0059] The separated mother liquor is placed in a distillation tower, and the tower bottom and the distillation tower are heated at normal pressure. During the distillation process, the tower bottom and the upper and lower sections of the distillation tower are always kept at the same temperature. The temperature of each heating point is gradually increased from 80°C. To maintain a stable state, the temperature is increased by 10°C each time, and each temperature is maintained for more than half an hour. When a distillate is produced, the distillate is collected at a reflux ratio of 1:1 after maintaining full reflux for 10 minutes. The temperature is heated to 240°C to obtain recovered sulfuric acid, and the concentration of sulfuric acid finally reaches more than 97%.

[0060] Embodiment 3:

[0061] The wastewater obtained by C-nitration reaction in the production process of 3,4-dinitropyrazole has the following physical and chemical properties: pH = 1, 3,4-dinitropyrazole content is about 3.95%, H2SO4 content is about 29.1%, HNO3 content is about 3.3%, and the waste liquid is mixed with ethyl acetate as an extractant in a volume ratio of 1:1 and shaken. Extract 1, 2, 3, 4, and 5 times respectively. After standing, when the interface between the two phases is clear, open the cover of the separatory funnel and turn the knob to separate the two phases, and calculate the 3,4-dinitropyrazole content in the two phases. Figure 4 As shown in the figure, when ethyl acetate is used as the extractant, the total extraction effect increases with the number of extractions, which is 84.9%, 99.5%, 99.6%, 99.8%, and 99.8% in sequence. The extraction effect of each extraction increases first, then decreases and tends to be stable, which is 84.9%, 97.2%, 39.4%, 34.0%, and 35.7% in sequence.

[0062] The separated extract was placed in a vacuum distillation apparatus, the vacuum degree in the reactor was adjusted to -0.1 MPa, and rotary distillation was performed at 80°C. After all the liquid was distilled out, 3,4-dinitropyrazole solid ( Figure 5 ), and the recovery rate can reach 96%.

[0063] Place the separated mother liquor in a distillation tower, and start heating the tower bottom and the distillation tower under normal pressure. During the distillation process, always keep the tower bottom and the upper and lower sections of the distillation tower at the same temperature. The temperature of each heating point gradually rises from 80°C. To maintain a stable state, the temperature is raised by 10°C each time, and each temperature is maintained for more than half an hour. When a distillate is produced, keep full reflux for 10 minutes, then start collecting the distillate at a reflux ratio of 1:1, and heat it to 240°C. Figure 6 As shown, it can be seen that the content of sulfuric acid increases with time, especially at 130°C, the content increases sharply. When it reaches 240°C, the recovered sulfuric acid is obtained, and the concentration of sulfuric acid finally reaches more than 97%, and the COD content is less than 100 mg / L. Figure 7 As shown, the content of nitric acid drops sharply from 80°C. When the temperature reaches 110°C, all the nitric acid is vaporized to generate nitrogen oxides which are eliminated. When the temperature reaches 240°C, the nitric acid content is less than 0.01%.

[0064] The present invention also provides a system for recycling nitropyrazole mixed acid waste liquid, which implements the method for recycling nitropyrazole mixed acid waste liquid, comprising: a mixing module, an extraction module, a rotary evaporation module and a distillation module;

[0065] The mixing module includes a conical flask and a water bath constant temperature oscillator, which is used to degrade pyrazole and N-nitropyrazole in N-nitration waste acid;

[0066] It is worth noting that the conical flask is only a reaction container option for an experimental environment. In engineering practice, any reaction container with mixing function used by those skilled in the art to implement the present invention falls within the scope of the present invention.

[0067] The extraction module includes a separatory funnel for separating 3,4-dinitropyrazole and sulfuric acid;

[0068] The rotary evaporation module includes a vacuum distillation device for rotary evaporation to recover 3,4-dinitropyrazole;

[0069] The distillation module comprises a tower kettle and a distillation tower, and is used for distilling and recovering sulfuric acid.

[0070] Compared with the prior art, the beneficial effects of the present invention include at least:

[0071] The invention adopts advanced oxidation technology in the process of treating N-nitration waste acid solution, without oxidant, and utilizes acetic acid solution and added iron filings in wastewater to achieve effective degradation of pyrazole and N-nitropyrazole; in C-nitration process, compared with the traditional high-temperature heating process, the extraction method using extractant can effectively reduce costs, is simple to operate, avoids the risk of DNP explosion caused by high-temperature heating, and the DNP extraction recovery rate reaches 99.8%. The method of the invention realizes the separation of nitric acid and sulfuric acid in the mother liquor after extraction, and recycles sulfuric acid, the concentration of sulfuric acid after recovery reaches 97%, and the COD content is lower than 100mg / L.

[0072] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention rather than to limit it. Although the present invention has been described in detail with reference to the above embodiments, ordinary technicians in the relevant field should understand that the specific implementation methods of the present invention can still be modified or replaced by equivalents, and any modifications or equivalent replacements that do not depart from the spirit and scope of the present invention should be covered within the scope of protection of the claims of the present invention.

Claims

1. A method for recycling nitropyrazole mixed acid waste liquid, characterized in that: include: Advanced oxidation treatment of pyrazole and N-nitropyrazole in N-nitration waste acid and recovery of 3,4-dinitropyrazole and sulfuric acid from C-nitration process wastewater; The advanced oxidation treatment of pyrazole and N-nitropyrazole in N-nitration waste acid comprises: taking N-nitration waste acid solution, mixing with a set amount of iron filings, and shaking at a constant temperature under set conditions to obtain a waste liquid after degrading pyrazole and N-nitropyrazole; The method for recovering 3,4-dinitropyrazole and sulfuric acid from waste liquid of C-nitration process comprises: using an extractant to recover 3,4-dinitropyrazole in the C-nitration process and using a distillation method to recover sulfuric acid in the C-nitration process.

2. A method for recycling nitropyrazole mixed acid waste liquid according to claim 1, characterized in that: The N-nitration waste acid solution is prepared by diluting the N-nitration waste water solution and placing the diluted solution in a reaction container.

3. A method for recycling nitropyrazole mixed acid waste liquid according to claim 1, characterized in that: The set amount of iron filings is 0.01 g to 0.1 g of iron filings added to the reaction container.

4. The method for recycling nitropyrazole mixed acid waste liquid according to claim 1, characterized in that: The set conditions are as follows: the reaction container is placed in a water bath constant temperature oscillator and oscillated at room temperature and 0-300 rpm, and the reaction time is 0-300 min.

5. The method for recycling nitropyrazole mixed acid waste liquid according to claim 1, characterized in that: The method for recovering 3,4-dinitropyrazole and sulfuric acid from C-nitration process waste liquid specifically comprises: Place the C-nitration process waste liquid and the extractant in a separatory funnel in proportion and mix thoroughly, shake well and let stand to obtain a solution with a clear interface between the two phases; Open the lid of the separatory funnel and turn the knob to separate the two phases; The separated extract is placed in a vacuum distillation apparatus, and rotary distilled under set conditions to recover 3,4-dinitropyrazole; The mother liquor separated above is taken and placed in a distillation tower, the distillation temperature is adjusted, and sulfuric acid is recovered.

6. A method for recycling nitropyrazole mixed acid waste liquid according to claim 5, characterized in that: The content of 3,4-dinitropyrazole in the C-nitration process waste liquid is not less than 3.95%, and the extractant is ethyl acetate.

7. A method for recycling nitropyrazole mixed acid waste liquid according to claim 5, characterized in that: The set conditions for rotary evaporation are to adjust the vacuum degree to -0.1 MPa and perform rotary evaporation at 80°C.

8. The method for recycling nitropyrazole mixed acid waste liquid according to claim 5, characterized in that: During the distillation process, the tower kettle and the distillation tower are heated under normal pressure, and the temperatures of the tower kettle and the upper and lower sections of the distillation tower are always kept the same. The temperature of each heating point is gradually increased from 80°C, by 10°C each time, and each temperature is maintained for more than half an hour.

9. A method for recycling nitropyrazole mixed acid waste liquid according to claim 8, characterized in that: During the distillation process, when a fraction is generated, the fraction is collected at a reflux ratio of 1:1 after maintaining full reflux for 10 minutes.

10. A system for recycling nitropyrazole mixed acid waste liquid, which implements the method for recycling nitropyrazole mixed acid waste liquid according to any one of claims 1 to 9, characterized in that: include: Mixing module, extraction module, rotary evaporation module and distillation module; The mixing module includes a conical flask and a water bath constant temperature oscillator, which is used to degrade pyrazole and N-nitropyrazole in N-nitration waste acid; The extraction module includes a separatory funnel for separating 3,4-dinitropyrazole and sulfuric acid; The rotary evaporation module includes a vacuum distillation device for rotary evaporation to recover 3,4-dinitropyrazole; The distillation module comprises a tower kettle and a distillation tower, and is used for distilling and recovering sulfuric acid.

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