CN-118005527-B - Recycling treatment method of formamide production wastewater

Abstract

The invention relates to the technical field of industrial wastewater treatment, and particularly discloses a recycling treatment method of formamide production wastewater. The method comprises the steps of pretreating formamide production wastewater by using microbubbles, freezing, effectively reducing impurity occlusion in the formamide solid obtained by crystallization, improving the separation efficiency of formamide from wastewater, adding water into the obtained formamide solid crude product to melt, repeating the steps of microbubble pretreatment and freezing until the formamide solid with the purity of more than 95% is obtained, dissolving the formamide solid in a dichloromethane extractant for microbubble treatment, improving the extraction efficiency of dichloromethane on the formamide impurities, extracting and separating to obtain a formamide product with the purity of more than 99.6%, and distilling raffinate to obtain an avermectin byproduct with the content of more than 80%. The invention realizes the recycling utilization of the formamide wastewater, has higher economic benefit and environmental protection benefit, and has higher popularization and application value.

Inventors

• LIU CHUN
• MENG LIE
• ZHOU HONGZHENG
• WANG SHAN
• NIU JIANRUI
• GUO XIAOLIN
• ZHANG JING
• ZHAO JUNHUA

Assignees

• 河北科技大学
• 河北美荷药业有限公司

Dates

Publication Date

20260505

Application Date

20231226

Claims (9)

1. 1. A recycling treatment method of formamide production wastewater is characterized by comprising the following steps: S1, carrying out micro-bubble treatment on formamide production wastewater, carrying out gradient freezing at-30-0 ℃ and carrying out solid-liquid separation to obtain a formamide solid a; s2, adding the formamide solid a into water, and uniformly mixing to obtain a formamide solution a; s3, carrying out micro-bubble treatment on the formamide solution a, carrying out gradient freezing at-30-0 ℃ and carrying out solid-liquid separation to obtain a formamide solid b; S4, repeating the step S1-step S3 on the formamide solid b until the purity of the obtained formamide solid is more than 95%, so as to obtain a formamide solid c; S5, performing heat exchange on the formamide solid c and the formamide production wastewater to be treated through a non-contact heat exchanger to obtain molten formamide, then adding methylene dichloride into the molten formamide, performing micro-bubble treatment on the obtained formamide solution, standing for phase separation to obtain a formamide liquid product and a methylene dichloride extraction phase; S6, rectifying the dichloromethane extract phase to obtain abamectin and dichloromethane; in S1 and S3, the specific steps of gradient freezing are that the gradient freezing is carried out for 1 to 2 hours at-10 ℃ to 0 ℃, then for 1 to 2 hours at-20 ℃ to-10 ℃, and finally for 2 to 3 hours at-30 ℃ to-20 ℃; The formamide production wastewater is wastewater generated in the process of leaching and refining the avermectin, and comprises formamide, avermectin, other organic matters and water.
2. 2. The method for recycling carboxamide industrial wastewater according to claim 1, wherein in S1 and S3, the time for the microbubble treatment is 5 min-10 min, and/or In S1 and S3, in the micro-bubble treatment, the volume ratio of the formamide production wastewater to the air flow is 100:7-100:10, and the proportion of the micro-bubble particle diameter <30 mu m to all bubbles is more than 80%.
3. 3. The recycling treatment method of formamide production wastewater according to claim 1, wherein in S1 and S3, the cooling rate of gradient freezing is 0.2 ℃ per minute to 0.4 ℃ per minute.
4. 4. The recycling treatment method of formamide production wastewater according to claim 1, wherein in S2, the method further comprises the steps of carrying out heat exchange on formamide solid a and the formamide production wastewater to be treated through a non-contact heat exchanger to obtain molten formamide, adding water into the molten formamide, mixing uniformly to obtain formamide solution a, and returning the formamide production wastewater subjected to heat exchange to the step a for wastewater treatment.
5. 5. The method for recycling formamide production wastewater according to claim 4, wherein in S2, the mass ratio of the formamide solid a to the water is 10:1-15:1, and/or And S2, controlling the temperature of the melted formamide to be 5-10 ℃.
6. 6. The recycling method of formamide industrial wastewater according to claim 1, wherein in S5, the formamide industrial wastewater after heat exchange is returned to the step a for wastewater treatment.
7. 7. The recycling treatment method of formamide production wastewater according to claim 1 or 6, wherein in S5, the mass ratio of the melted formamide to the dichloromethane is 8:1-10:1.
8. 8. The method for recycling carboxamide production wastewater according to claim 1, wherein in S5, the time for the microbubble treatment is 20 min-30 min, and/or In S5, in the micro-bubble treatment, the volume ratio of the formamide solution to the air flow is 100:7-100:10, and the proportion of the micro-bubble particle diameter <30 mu m accounting for all bubbles is more than 80%.
9. 9. The recycling treatment method of formamide production wastewater according to claim 1, wherein in the step S6, rectification is performed under normal pressure, the bottom temperature of a rectifying tower is 48-115 ℃, the temperature of liquid in the rectifying tower is 43-110 ℃, the top temperature of the rectifying tower is 40-110 ℃, and the reflux ratio is 10:1-5:1.

Description

Recycling treatment method of formamide production wastewater Technical Field The invention relates to the technical field of industrial wastewater treatment, in particular to a recycling treatment method of formamide production wastewater. Background The formamide has active reactivity and excellent solubility, can be widely applied to organic synthesis, medicine and fiber industry, can carry out dehydration, carbon monoxide removal, graft acyl, cyclization and other reactions, can be used for producing sulfonamides, vitamins and serving as softeners for paper and fibers, and has wide application in the fields of pesticides, pigments, fragrances, assistants and the like, and has very broad market prospect. The formamide waste water from the extraction and refining process of avermectin mainly contains formamide, avermectin, other organic matters and the like, and the waste water has high organic matter content and high toxicity, so that the waste water cannot directly enter a sewage biochemical treatment system. At present, the waste water containing formamide is generally treated according to a hazardous waste management method in the industry, the treatment cost is high, and the formamide in the waste water can not be recycled, so that the resource waste is caused. Since formamide has excellent solubility, is miscible with water, various alcohols and organic solvents, has a low boiling point, and can be partially decomposed at 220 ℃ or above under normal pressure and 70.5 ℃ or above under 133.3Pa pressure, recovery of formamide is difficult to achieve by conventional methods of concentration and recovery of formamide, such as heating evaporation concentration, vacuum concentration, organic film treatment, adsorption and the like. In order to reduce the emission of hazardous waste and reduce the sewage treatment cost of enterprises, it is imperative to develop a treatment method of formamide waste water which can recycle various components of the waste water and has low cost. Disclosure of Invention Aiming at the problem that the prior formamide production wastewater can not be recycled, the invention provides a recycling treatment method of the formamide production wastewater, which mainly adopts the technologies of micro-bubble treatment, coupling repeated freezing crystallization, distilled water washing, dichloromethane extraction and the like, thereby realizing the treatment of the production wastewater, recycling formamide and avermectin in the production wastewater, the purity of the recycled formamide can reach more than 99 percent, the purity of the avermectin can reach more than 80 percent, and the method can be directly sold as a product, thereby increasing the income of enterprises and having higher economic and environmental benefits. In order to solve the technical problems, the technical scheme provided by the invention is as follows: A recycling treatment method of formamide production wastewater comprises the following steps: S1, carrying out micro-bubble treatment on formamide production wastewater, carrying out gradient freezing at-30-0 ℃ and carrying out solid-liquid separation to obtain a formamide solid a; s2, adding the formamide solid a into water, and uniformly mixing to obtain a formamide solution a; s3, carrying out micro-bubble treatment on the formamide solution a, carrying out gradient freezing at-30-0 ℃ and carrying out solid-liquid separation to obtain a formamide solid b; S4, repeating the step S1-step S3 on the formamide solid b until the purity of the obtained formamide solid is more than 95%, so as to obtain a formamide solid c; s5, adding the formamide solid c into dichloromethane, carrying out micro-bubble treatment on the obtained formamide solution, standing for phase separation to obtain a formamide liquid product and a dichloromethane extraction phase; And S6, rectifying the dichloromethane extract phase to obtain abamectin and dichloromethane. Compared with the prior art, the recycling treatment method of the formamide production wastewater provided by the invention has the advantages that firstly, the formamide production wastewater is pretreated by the micro-bubbles and then frozen, the surfaces of the micro-bubbles are provided with high-charge particles, the specific surface area is large, the residence time in water is long, and the thermal stability of the solution can be changed, so that the impurity occlusion in the formamide solid obtained by crystallization can be effectively reduced by re-freezing after the micro-bubble pretreatment, and meanwhile, the separation efficiency of the formamide from the wastewater can be improved; adding water into the obtained formamide solid crude product to melt, repeating the steps of microbubble pretreatment and freezing until the formamide solid with the purity of more than 95 percent is obtained, dissolving the formamide solid into a dichloromethane extractant, performing microbubble treatment to improve the extract