Purification and recovery device for waste liquid containing N-methyl pyrrolidone

Abstract

The embodiment of the utility model discloses a purification and recovery device for waste liquid containing N-methyl pyrrolidone. According to one specific embodiment, the purification and recovery device for the waste liquid containing the N-methyl pyrrolidone comprises a first membrane separation assembly, a second membrane separation assembly, a third membrane separation assembly, a fourth membrane separation assembly and a rectifying tower, and the second membrane separation assembly is connected to the permeation side of the first membrane separation assembly; the rectifying tower is connected to the retentate side of the second membrane separation assembly; the third membrane separation assembly is connected to a tower kettle of the rectifying tower; and the fourth membrane separation assembly is connected to the permeation side of the third membrane separation assembly. According to the embodiment, the purity of the recovered N-methyl pyrrolidone can be improved.

Description

TECHNICAL FIELD

[0001] Embodiments of the present disclosure relate to the technical field of industrial wastewater treatment, in particular to a purification and recovery device for N-methyl pyrrolidone-containing waste liquid. BACKGROUND

[0002] In modern industry, N-methyl pyrrolidone is widely used in electronic component cleaning, and its high solubility and low residue can effectively remove dirt and impurities. This leads to a large amount of N-methyl pyrrolidone-containing waste liquid. The composition of the waste liquid is complex and contains many impurities. If it is directly discharged, not only will it cause resource waste, but also will cause serious environmental pollution. Therefore, purification and recovery of N-methyl pyrrolidone-containing waste liquid has important economic and environmental protection significance.

[0003] At present, the purification of N-methyl pyrrolidone-containing waste liquid mainly uses extraction devices. However, when the above device is used to purify N-methyl pyrrolidone-containing waste liquid, the following technical problems often exist: when the extraction device is used to purify N-methyl pyrrolidone-containing waste liquid, the extractant may remain in the recovered N-methyl pyrrolidone. Even after subsequent separation operation, it is difficult to completely remove the extractant. This will affect the purity of the recovered N-methyl pyrrolidone, so that it cannot meet some application scenarios with high purity requirements, such as the recovery of electronic-grade N-methyl pyrrolidone.

[0004] The above information disclosed in this BACKGROUND section is only for the purpose of enhancing the understanding of the background of the present disclosure and therefore, it can contain information that does not form the prior art that is already known to those of ordinary skill in the art in this country. SUMMARY

[0005] The summary of the present disclosure is used to introduce the concepts in a brief manner, which will be described in detail in the specific embodiments section. The summary of the present disclosure is not intended to identify key or essential features of the claimed technical solutions, nor is it intended to be used to limit the scope of the claimed technical solutions.

[0006] Some embodiments of the present disclosure propose a purification and recovery device for N-methyl pyrrolidone-containing waste liquid to solve one or more of the technical problems mentioned in the above BACKGROUND section.

[0007] Some embodiments of the present disclosure provide a device for purifying and recycling N-methylpyrrolidone-containing waste liquid, characterized in that the device comprises a first membrane separation assembly, a second membrane separation assembly, a third membrane separation assembly, a fourth membrane separation assembly, and a rectifying column, wherein the second membrane separation assembly is connected to the permeate side of the first membrane separation assembly; the rectifying column is connected to the retentate side of the second membrane separation assembly; the third membrane separation assembly is connected to the column bottom of the rectifying column; and the fourth membrane separation assembly is connected to the permeate side of the third membrane separation assembly.

[0008] Optionally, the first membrane separation assembly comprises an ultrafiltration membrane configured to remove solid particles in the N-methylpyrrolidone-containing waste liquid.

[0009] Optionally, a heat exchanger is further provided between the first membrane separation assembly and the second membrane separation assembly.

[0010] Optionally, the heat exchanger is connected to the top of the rectifying column.

[0011] Optionally, a raw material tank is connected to the retentate side of the first membrane separation assembly, and the raw material tank is configured to contain the N-methylpyrrolidone-containing waste liquid.

[0012] Optionally, an intermediate tank is further provided between the third membrane separation assembly and the fourth membrane separation assembly.

[0013] Optionally, a condenser is further provided between the third membrane separation assembly and the intermediate tank.

[0014] Optionally, a product tank is connected to the permeate side of the fourth membrane separation assembly.

[0015] Optionally, a second vacuum pump is connected to the permeate side of the second membrane separation assembly; and a first vacuum pump is connected to the permeate side of the third membrane separation assembly.

[0016] Optionally, a first circulating pump is connected to the retentate side of the first membrane separation assembly; a second circulating pump is connected between the rectifying column and the third membrane separation assembly; and a third circulating pump is connected to the retentate side of the fourth membrane separation assembly.

[0017] Some embodiments of the present disclosure provide a purification and recovery device for N-methylpyrrolidone-containing waste liquid, which can improve the purity of recovered N-methylpyrrolidone. Specifically, the reason for the low purity of recovered N-methylpyrrolidone is that currently, the purification of N-methylpyrrolidone-containing waste liquid mainly uses an extraction device. When the N-methylpyrrolidone-containing waste liquid is purified by using the extraction device, the extractant may remain in the recovered N-methylpyrrolidone. Even after subsequent separation operations, it is difficult to completely remove the extractant. This results in low purity of the recovered N-methylpyrrolidone. Based on this, some embodiments of the present disclosure provide a purification and recovery device for N-methylpyrrolidone-containing waste liquid, which includes a first membrane separation assembly, a second membrane separation assembly, a third membrane separation assembly, a fourth membrane separation assembly, and a rectifying column. The second membrane separation assembly is connected to the permeation side of the first membrane separation assembly. The rectifying column is connected to the retentate side of the second membrane separation assembly. The third membrane separation assembly is connected to the column bottom of the rectifying column. The fourth membrane separation assembly is connected to the permeation side of the third membrane separation assembly. Because the purification and recovery device for N-methylpyrrolidone-containing waste liquid relies on the filtration of the first membrane separation assembly, the second membrane separation assembly, the third membrane separation assembly, and the fourth membrane separation assembly and the rectification of the rectifying column to achieve the purification and recovery of the N-methylpyrrolidone-containing waste liquid, it is not necessary to add an extractant to the waste liquid, thereby avoiding the introduction of other impurities. In addition, the fourth membrane separation assembly can remove trace metal ions in the waste liquid. Thus, the purity of the recovered N-methylpyrrolidone can be improved to meet the electronic grade standard. BRIEF DESCRIPTION OF DRAWINGS

[0018] The above and other features, advantages, and aspects of embodiments of the present disclosure will become more apparent upon consideration of the following detailed description, taken in conjunction with the accompanying drawings. In the drawings like reference numerals designate like elements throughout the various figures. It should be understood that the drawings are schematic and elements and features are not necessarily drawn to scale.

[0019] Figure 1 is a schematic diagram of a purification and recovery device for N-methylpyrrolidone-containing waste liquid according to some embodiments of the present disclosure;

[0020] Figure 2 is a schematic diagram of a purification and recovery device for N-methylpyrrolidone-containing waste liquid according to some other embodiments of the present disclosure;

[0021] Figure 3 is a schematic diagram of a purification and recovery device for N-methylpyrrolidone-containing waste liquid according to yet some other embodiments of the present disclosure. DETAILED DESCRIPTION

[0022] Embodiments of the present disclosure will be described below in greater detail with reference to the accompanying drawings. While certain embodiments of the present disclosure are shown in the drawings, it is understood that the present disclosure can be embodied in various forms and should not be construed as being limited to the embodiments set forth herein. Rather, these embodiments are provided so as to more completely and thoroughly understand the present disclosure. It should be understood that the drawings and embodiments of the present disclosure are for exemplary purposes only and are not intended to limit the scope of protection of the present disclosure.

[0023] It should also be noted that only parts related to the present application are shown in the drawings for the convenience of description. The embodiments in the present disclosure and the features in the embodiments can be combined with each other without conflict.

[0024] It should be noted that the concepts of "first", "second" and the like mentioned in the present disclosure are only used to distinguish different devices, modules or units, and are not intended to limit the order or interdependence of the functions performed by these devices, modules or units.

[0025] It should be noted that the adjectives "one", "multiple" mentioned in the present disclosure are illustrative and not limiting, and those skilled in the art should understand that unless otherwise explicitly stated in the context, it should be understood as "one or more".

[0026] The names of the messages or information exchanged between the devices in the embodiments of the present disclosure are only for illustrative purposes, and are not intended to limit the scope of the messages or information.

[0027] The present disclosure will be described in detail below with reference to the accompanying drawings and in conjunction with the embodiments.

[0028] Figure 1 is a schematic diagram of a purification and recovery device for N-methylpyrrolidone waste liquid of some embodiments of the present disclosure. Figure 1 It includes a raw material tank 1, a first membrane separation assembly 3, a heat exchanger 4, a second membrane separation assembly 5, a rectifying column 6, a third membrane separation assembly 7, a condenser 8, a fourth membrane separation assembly 9, a product tank 11, a first vacuum pump 14, and a second vacuum pump 15.

[0029] In some embodiments, the above-mentioned purification and recovery device for N-methylpyrrolidone-containing waste liquid can include a first membrane separation assembly 3, a second membrane separation assembly 5, a third membrane separation assembly 7, a fourth membrane separation assembly 9, and a rectifying column 6. The N-methylpyrrolidone-containing waste liquid can pass through the above-mentioned first membrane separation assembly 3, the above-mentioned second membrane separation assembly 5, the above-mentioned rectifying column 6, the above-mentioned third membrane separation assembly 7, and the fourth membrane separation assembly 9 in sequence. The above-mentioned first membrane separation assembly 3 can include, but is not limited to, at least one of the following: a microfiltration membrane, an ultrafiltration membrane, a nanofiltration membrane, and a reverse osmosis membrane. The above-mentioned first membrane separation assembly 3 can be used to filter out solid impurities such as suspended particles contained in the N-methylpyrrolidone-containing waste liquid.

[0030] In some embodiments, the second membrane separation module 5 can comprise a water- permeable membrane. The second membrane separation module 5 can be connected to the permeate side of the first membrane separation module 3. The second membrane separation module 5 can be used to separate water from the N-methyl pyrrolidone-containing waste liquid treated by the first membrane separation module 3. Since the second membrane separation module 5 is a water-permeable membrane, the permeate side of the second membrane separation module 5 is water, and the retentate side of the second membrane separation module 5 is the N-methyl pyrrolidone-containing waste liquid after water separation. Therefore, the retentate side of the second membrane separation module 5 can be connected to the rectification column 6.

[0031] In some embodiments, the rectification column 6 can use the difference in boiling points of the components in the waste liquid treated by the second membrane separation module 5 to achieve the separation function. For example, for the N-methyl pyrrolidone-containing waste liquid, there is a difference in boiling points between N-methyl pyrrolidone (boiling point about 202°C) and water (boiling point 100°C) or other low-boiling-point impurities. In the rectification column 6, the N-methyl pyrrolidone-containing waste liquid is partially vaporized by heating, and the generated vapor rises in the column and repeatedly contacts the descending condensed liquid for multiple times of heat and mass exchange. The concentration of volatile components (such as low-boiling-point impurities or water) in the gas phase gradually increases, and the concentration of non-volatile components (such as N-methyl pyrrolidone) in the liquid phase gradually increases, thereby achieving the purpose of separation. During this period, the operating conditions of the rectification column 6 can be set as follows: reflux ratio 0.5-5, number of trays 20-50, column top temperature control 90-110°C, column bottom temperature control 110-130°C, and column absolute pressure 5-15 kPa. Since N-methyl pyrrolidone has a high boiling point, it mainly exists in the column bottom of the rectification column 6. Therefore, the third membrane separation module 7 can be connected to the column bottom.

[0032] In some embodiments, the third membrane separation module 7 can comprise a N-methyl pyrrolidone-permeable membrane. The N-methyl pyrrolidone-permeable membrane can be a pervaporation membrane prepared by using polydimethylsiloxane (PDMS) as the basic membrane material. Because the PDMS pervaporation membrane has selective permeability to N-methyl pyrrolidone, it can achieve the separation of N-methyl pyrrolidone from other organic impurities. For example, the N-methyl pyrrolidone-containing waste liquid in the column bottom of the rectification column 6 after rectification treatment can be introduced into the retentate side of the third membrane separation module 7, and the permeate side can be reduced in pressure by vacuumizing or purging with inert gas, so that N-methyl pyrrolidone can permeate from the retentate side to the permeate side of the third membrane separation module 7 under the action of the component vapor partial pressure difference between the two sides of the third membrane separation module 7.

[0033] In some embodiments, the fourth membrane separation component 9 can be connected to the permeate side of the third membrane separation component 7. The fourth membrane separation component 9 can include a metal ion de-chelating membrane. The fourth membrane separation component 9 can be used to separate metal ions from N-methylpyrrolidone-containing wastewater treated by the third membrane separation component 7. The principle by which the fourth membrane separation component 9 removes metal ions is that the metal ion de-chelating membrane has specific chelating groups, such as amino, carboxyl, hydroxyl, and mercapto groups. These groups can form stable chelates with metal ions. When N-methylpyrrolidone containing metal ions comes into contact with the metal ion de-chelating membrane, the chelating groups on the membrane preferentially undergo coordination reactions with specific metal ions, forming multiple coordination bonds that firmly bind the metal ions to the membrane surface or within the membrane pores. When the waste liquid containing N-methylpyrrolidone passes through the first membrane separation component 3, the second membrane separation component 5, the distillation column 6, the third membrane separation component 7, and the fourth membrane separation component 9 in sequence, electronic-grade high-purity N-methylpyrrolidone that meets the needs of industrial production can be obtained on the permeate side of the fourth membrane separation component.

[0034] Optionally, the first membrane separation component 3 may include an ultrafiltration membrane. The first membrane separation component 3 can be used to filter out solid particles from N-methylpyrrolidone-containing waste liquid to prevent solid particles from damaging or clogging downstream devices during subsequent purification processes. The ultrafiltration membrane can be made of one of polysulfone, polyethersulfone, polyvinylidene fluoride, or alumina ceramic membranes, and the membrane pore size can be between 0.01 and 0.1 micrometers.

[0035] Optionally, such as Figure 1 As shown, a heat exchanger 4 can be provided between the first membrane separation component 3 and the second membrane separation component 5. The heat exchanger 4 can be a gas-liquid heat exchanger (such as a tubular heat exchanger). The heat exchanger 4 can be used to preheat the N-methylpyrrolidone-containing waste liquid treated by the first membrane separation component 3. The purpose of preheating the N-methylpyrrolidone-containing waste liquid is to improve the dehydration efficiency of the subsequent N-methylpyrrolidone-containing waste liquid by the second membrane separation component 5. The reason is as follows:

[0036] First, it reduces viscosity. Waste liquid containing N-methylpyrrolidone typically has a certain viscosity. Preheating raises the temperature of the waste liquid, intensifies molecular motion, and thus reduces its viscosity, enhancing its fluidity. This allows the waste liquid to flow and diffuse more easily within the equipment during dehydration, resulting in better contact with the dehydration medium or equipment surface and improved dehydration efficiency.

[0037] Secondly, it promotes water evaporation. Increased temperature increases the saturated vapor pressure of water, making it easier for water to change from a liquid to a gaseous state. After preheating, the water in the waste liquid will evaporate more quickly during the dehydration process, thus accelerating the dehydration speed and improving dehydration efficiency.

[0038] Optionally, such as Figure 1 As shown, the heat exchanger 4 can be connected to the top of the distillation column 6. During distillation, the N-methylpyrrolidone-containing waste liquid is decomposed into a light vapor component at the top of the column and a heavy component at the bottom. The light vapor component carries a high temperature. Therefore, connecting the heat exchanger 4 to the top of the distillation column 6 allows the heat carried by the light vapor component to preheat the N-methylpyrrolidone-containing waste liquid after treatment by the first membrane separation component 3. Simultaneously, the light vapor component can be condensed and returned to the waste liquid for continued circulation, achieving efficient energy utilization.

[0039] Optionally, such as Figure 1 As shown, the permeate side of the first membrane separation component 3 can be connected to a feed tank 1. The feed tank 1 can be used to contain waste liquid containing N-methylpyrrolidone. The purpose of connecting the feed tank 1 to the permeate side of the first membrane separation component 3 is that the waste liquid contained in the feed tank 1 can be directly passed to the first membrane separation component 3 for solid particle filtration.

[0040] Optionally, such as Figure 2 As shown, an intermediate tank 10 is provided between the third membrane separation component 7 and the fourth membrane separation component 9. The intermediate tank 10 can be used to contain the waste liquid treated by the third membrane separation component 7. Since the third membrane separation component 7 can be a pervaporation membrane, the waste liquid treated by it is in a vapor state. Therefore, in order to carry out the next purification process, the vaporized waste liquid needs to be condensed first. The intermediate tank 10 can also play a condensation role to some extent.

[0041] Optionally, such as Figure 1 As shown, a condenser 8 may also be provided between the third membrane separation component 7 and the intermediate tank 10. The condenser 8 allows the waste liquid, which is in a gaseous state after being treated by the third membrane separation component 7, to be condensed. During the condensation process, the condenser 8 can be the primary component, with the intermediate tank 10 serving as a secondary component, to achieve a better condensation effect. The type of condenser 8 may include, but is not limited to, any of the following: a water-cooled condenser and an air-cooled condenser.

[0042] Optionally, such as Figure 1As shown, the permeate side of the fourth membrane separation component 9 can be connected to a product tank 11. The product tank 11 can be used to contain the N-methylpyrrolidone finished product obtained after purification and recovery of waste liquid containing N-methylpyrrolidone. Since N-methylpyrrolidone is an organic solvent with certain chemical activity, the material of the product tank 11 must be able to withstand the corrosion of N-methylpyrrolidone; at the same time, to meet electronic grade requirements, there must be no excessive metal ion precipitation. For example, a stainless steel storage tank with an inner lining can be used. The material of the inner lining can be one or more of the following, including but not limited to: soluble polytetrafluoroethylene (PFA), polytetrafluoroethylene (PTFE), and polyvinylidene fluoride (PVDF). No specific limitation is made here regarding the material of the product tank 11.

[0043] Optionally, such as Figure 1 As shown, a second vacuum pump 15 can be connected to the permeate side of the second membrane separation component 5. A first vacuum pump 14 can be connected to the permeate side of the third membrane separation component 7. The second vacuum pump 15 can reduce the pressure on the permeate side of the second membrane separation component 5. Since the second membrane separation component 5 may include a water-permeable membrane, the pressure difference across the membrane is one of the driving forces for water to permeate through the membrane, according to the principle of osmotic pressure. Since the third membrane separation component 7 may include a N-methylpyrrolidone membrane, the first vacuum pump 14 can reduce the pressure on the permeate side of the N-methylpyrrolidone membrane. Because the permeation of N-methylpyrrolidone molecules is driven by the pressure difference, the negative pressure generated by the vacuum pump makes it easier for N-methylpyrrolidone molecules to permeate from the retentate side to the permeate side, thereby improving the recovery efficiency. The second vacuum pump 15 and the first vacuum pump 14 can be of the same type, including but not limited to any of the following: rotary vane vacuum pump, water ring vacuum pump, and Roots vacuum pump.

[0044] Optionally, such as Figure 3As shown, the retentate side of the first membrane separation assembly 3 can be connected with a first circulation pump 2. The rectifying column 6 and the third membrane separation assembly 7 can be connected with a second circulation pump 12. The retentate side of the fourth membrane separation assembly 9 can be connected with a third circulation pump 13. The first circulation pump 2, the second circulation pump 12 and the third circulation pump 13 can be of the same model or different models. The first circulation pump 2, the second circulation pump 12 and the third circulation pump 13 all serve to provide power for the purification and recovery device for the N-methylpyrrolidone-containing waste liquid. The first circulation pump 2, the second circulation pump 12 and the third circulation pump 13 can be of any one of the following types, but are not limited to: centrifugal pump, gear pump, diaphragm pump. The first circulation pump 2 can be a diaphragm pump, which has the advantage that the first circulation pump 2 is used to transport the untreated N-methylpyrrolidone-containing waste liquid. The untreated N-methylpyrrolidone-containing waste liquid can contain solid impurities, and the diaphragm pump can transport liquid containing a small amount of solid particles or impurities, because the diaphragm separates the liquid from the moving parts of the pump, avoiding damage to the internal structure of the pump by solid particles. At the same time, the diaphragm pump has good self-priming ability and can overcome problems such as cavitation and idling to some extent. Therefore, in the purification and recovery device for the N-methylpyrrolidone-containing waste liquid, if the waste liquid contains some impurities or needs to work at different liquid levels, the diaphragm pump is more suitable. The type of the first circulation pump 2, the second circulation pump 12 and the third circulation pump 13 is not specifically limited herein, as long as it can provide power for the purification and recovery device for the N-methylpyrrolidone-containing waste liquid.

[0045] Optionally, the second membrane separation assembly 5 can comprise a preferential water permeable membrane. The preferential water permeable membrane can be one of polyvinyl alcohol (PVA) membrane, polyimide (PI) membrane, chitosan membrane, and inorganic molecular sieve membrane. Further, the PVA membrane, PI membrane, and chitosan membrane can be a composite membrane structure. The composite membrane structure comprises a support layer and a selective layer. The support layer can be used to ensure the mechanical strength of the preferential water permeable membrane, and can maintain the shape and performance of the preferential water permeable membrane under different pressures and operating environments. Therefore, the material of the support layer can include, but is not limited to, any one of the following: polyether sulfone (PES), polysulfone (PSU), polyacrylonitrile (PAN), polyvinylidene fluoride (PVDF), and inorganic ceramic. The selective layer can selectively retain different substances according to the size or other characteristics of the molecules. The selective layer can be composed of one or more of polyvinyl alcohol (PVA), polyimide (PI), and chitosan. The third membrane separation assembly 7 can comprise a preferential N-methylpyrrolidone permeable membrane. The preferential N-methylpyrrolidone permeable membrane can allow N-methylpyrrolidone in the waste liquid to pass through preferentially. At the same time, in order to prevent membrane pollution, the preferential N-methylpyrrolidone permeable membrane can be subjected to some special surface treatment, such as anti-pollution coating, to improve the service life of the membrane. The fourth membrane separation assembly 9 can comprise a metal ion removal chelating membrane. The metal ion removal chelating membrane can be used to remove metal ions contained in the waste liquid treated by the third membrane separation assembly 7, so as to further improve the purity of N-methylpyrrolidone. The metal ion removal chelating membrane can remove metal ions because the metal ion removal chelating membrane has specific chelating groups such as amino, carboxyl, hydroxyl, and sulfhydryl groups. These groups can form stable chelates with metal ions. Different chelating groups have selectivity for different metal ions, for example, amino and carboxyl groups can have good chelating ability for copper ions and nickel ions, while sulfhydryl groups have stronger affinity for mercury ions and silver ions. The principle of application in N-methylpyrrolidone purification and recovery is as follows: when N-methylpyrrolidone containing metal ions contacts the chelating membrane, the chelating groups on the membrane will preferentially coordinate with specific metal ions to form multiple coordination bonds, firmly binding the metal ions on the membrane surface or in the membrane pores.

[0046] The optional embodiment above is one of the inventive points of the embodiments of the present disclosure, and solves the technical problem of "low purity of N-methylpyrrolidone product obtained when using a membrane separation assembly for N-methylpyrrolidone purification and recovery". The factors that cause the low purity of the obtained N-methylpyrrolidone product are as follows: At present, when using a membrane for N-methylpyrrolidone purification and recovery, the membrane is usually used as an auxiliary device, and there is no device that integrates membranes with various separation functions in a system. If the above factors are solved, the effect of improving the purity of the obtained N-methylpyrrolidone product when using a membrane separation assembly for N-methylpyrrolidone purification and recovery can be achieved. In order to achieve this effect, the present disclosure further provides a device that organically integrates a preferential water-permeable membrane, a preferential N-methylpyrrolidone-permeable membrane, and a metal ion-removing chelating membrane in a system. In addition, the use of a membrane separation assembly can more efficiently and simply perform N-methylpyrrolidone purification and recovery. Thus, the purity of the N-methylpyrrolidone product is improved.

[0047] Some embodiments of the present disclosure provide a device for purifying and recovering N-methylpyrrolidone-containing waste liquid, which can improve the purity of the recovered N-methylpyrrolidone. Specifically, the reason for the low purity of the recovered N-methylpyrrolidone is that at present, the purification of N-methylpyrrolidone-containing waste liquid mainly uses an extraction device. When the extraction device is used to purify the N-methylpyrrolidone-containing waste liquid, the extractant may remain in the recovered N-methylpyrrolidone. Even after subsequent separation operations, it is difficult to completely remove the extractant. This results in low purity of the recovered N-methylpyrrolidone. Based on this, some embodiments of the present disclosure provide a device for purifying and recovering N-methylpyrrolidone-containing waste liquid, which includes a first membrane separation assembly, a second membrane separation assembly, a third membrane separation assembly, a fourth membrane separation assembly, and a rectifying column, wherein the second membrane separation assembly is connected to the permeation side of the first membrane separation assembly; the rectifying column is connected to the retentate side of the second membrane separation assembly; the third membrane separation assembly is connected to the column bottom of the rectifying column; and the fourth membrane separation assembly is connected to the permeation side of the third membrane separation assembly. Because the device for purifying and recovering N-methylpyrrolidone-containing waste liquid relies on the filtration of the first, second, third, and fourth membrane separation assemblies and the rectification of the rectifying column to achieve the purification and recovery of the N-methylpyrrolidone-containing waste liquid, it is not necessary to add an extractant to the waste liquid, thereby avoiding the introduction of other impurities. In addition, the fourth membrane separation assembly can remove trace metal ions in the waste liquid. Thus, the purity of the recovered N-methylpyrrolidone can be improved to meet the standard of electronic grade.

[0048] The above description is merely exemplary of some of the many possible embodiments of the present disclosure and of the principles thereof. It is to be understood that those skilled in the art will be able to devise various embodiments of the present disclosure without departing from the scope of the present disclosure as disclosed in the above description and attached claims, and that the scope of the present disclosure is not limited to the specific technical features described above. For example, the technical features described above can be replaced with other technical features with similar functions disclosed in the embodiments of the present disclosure (but not limited to) to form other technical solutions.

Claims

1. A purification and recovery apparatus for N-methylpyrrolidone-containing waste liquid, characterized by comprising: The purification and recovery device of the N-methyl pyrrolidone-containing waste liquid comprises a first membrane separation assembly, a second membrane separation assembly, a third membrane separation assembly, a fourth membrane separation assembly and a rectifying tower, wherein, The second membrane separation assembly is connected to the permeation side of the first membrane separation assembly; The rectifying tower is connected to the retentate side of the second membrane separation assembly; The third membrane separation assembly is connected to the tower bottom of the rectifying tower; The fourth membrane separation assembly is connected to the permeation side of the third membrane separation assembly.

2. The purification and recovery apparatus for N-methylpyrrolidone-containing waste liquid according to claim 1, characterized by The first membrane separation assembly comprises an ultrafiltration membrane configured to remove solid particles in the N-methyl pyrrolidone-containing waste liquid.

3. The purification and recovery apparatus for N-methylpyrrolidone-containing waste liquid according to claim 1, characterized by A heat exchanger is further arranged between the first membrane separation assembly and the second membrane separation assembly.

4. The purification and recovery apparatus for N-methylpyrrolidone-containing waste liquid according to claim 3, characterized by The heat exchanger is connected to the top of the rectifying tower.

5. The N-methylpyrrolidone-containing waste liquor purification recovery apparatus according to claim 1, characterized by The retentate side of the first membrane separation assembly is connected with a raw material tank configured to contain the N-methyl pyrrolidone-containing waste liquid.

6. The N-methylpyrrolidone-containing waste liquor purification recovery apparatus according to claim 1, characterized by An intermediate tank is further arranged between the third membrane separation assembly and the fourth membrane separation assembly.

7. The purification and recovery apparatus for N-methylpyrrolidone-containing waste liquid according to claim 6, characterized by A condenser is further arranged between the third membrane separation assembly and the intermediate tank.

8. The N-methylpyrrolidone-containing waste liquor purification recovery apparatus according to claim 1, characterized by The permeation side of the fourth membrane separation assembly is connected with a product tank.

9. The N-methylpyrrolidone-containing waste liquor purification recovery apparatus according to claim 1, characterized by The permeation side of the second membrane separation assembly is connected with a second vacuum pump; The permeation side of the third membrane separation assembly is connected with a first vacuum pump.

10. The N-methylpyrrolidone-containing waste liquor purification recovery apparatus according to claim 1, characterized by The retentate side of the first membrane separation assembly is connected with a first circulating pump; A second circulating pump is connected between the rectifying tower and the third membrane separation assembly; The retentate side of the fourth membrane separation assembly is connected with a third circulating pump.

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