KR20210082711A - Pervaporation membrane separation process for concentration of the organic compound and treatment of wastewater from specific organic compound containing wastewater - Google Patents

Abstract

The present invention relates to a pervaporation membrane separation process which dehydrates wastewater containing a specific organic compound such as NMP to concentrate the specific organic compound and can treat the wastewater at the same time. According to the present invention, the pervaporation membrane separation process dehydrates wastewater containing a specific organic compound such as NMP and selectively separates the specific organic compound, so that the organic compound can be concentrated at high concentration of up to 70.0 to 99.0 wt% to be recycled and wastewater containing an organic compound having a low concentration of 0.5 wt% or less can be treated in existing wastewater treatment plants without separate dilution and additional water treatment.

Description

Pervaporation membrane separation process for concentration of the organic compound and treatment of wastewater from specific organic compound containing wastewater

The present invention relates to a pervaporation membrane separation process for concentration and wastewater treatment of organic compounds from wastewater containing specific organic compounds, and more particularly, dehydration from wastewater containing specific organic compounds such as NMP to obtain the specific organic compounds. It relates to a pervaporation membrane separation process capable of treating wastewater at the same time as concentration.

N-methylpyrrolidone (NMP) is useful as a medium for various chemical reactions among specific organic compounds widely used for purposes such as organic solvents, as a cleaning agent in LCD and semiconductor manufacturing processes, as an extractant in the petrochemical industry, and at high cost. It is also used as a pesticide solvent in the manufacturing process of secondary batteries. In particular, NMP, which is used as an important solvent in the manufacturing process of cathode active materials for lithium-ion batteries, is entirely dependent on imports, and maintains high prices due to the monopoly of BASF and ISPs. For this reason, most lithium-ion battery manufacturers are using the method of recovering the NMP exhausted from the air during the drying process during the cathode manufacturing process and then reusing it. In Korea, a method of recovering from a wet scrubber using the hydrophilicity of NMP is mainly used, and the purity of NMP recovered in this way is about 60%.

On the other hand, as semiconductor devices are highly integrated, the number of manufacturing processes has increased. After each process, many residues or contaminants are left on the surface, so isopropyl alcohol (IPA) is used in the cleaning process to remove them. In the existing process, water was used to remove it, but the surface tension of water causes product defects to occur, and thus contaminants on the surface of the semiconductor wafer are removed using IPA, which evaporates easily. Since it takes a lot of cost to process such IPA wastewater through evaporation and concentration through the existing distillation method, the economic feasibility of recycling the wastewater is greatly reduced, and the toxicity of IPA kills microorganisms, making it difficult to treat with the existing biological treatment method. . Therefore, there is a need for a technology capable of efficiently concentrating and processing them to recycle resources.

In addition, dimethylacetamide (DMAC) and dimethylformamide (DMF) are colorless liquids with a fishy smell, and are well soluble in polar and non-polar substances. used Dimethyl sulfoxide (DMSO) is also used as a solvent for various resins, and due to the toxicity of these solvents, the discharge of wastewater is greatly restricted. Therefore, there is a need for more efficient and safe technology in recycling and disposing of it.

Accordingly, there have been prior studies for selectively separating water from a mixed solution of an organic compound/water such as NMP or for selectively separating an organic compound from an aqueous solution (Patent Documents 1, 2, 3), but mostly using a distillation process or reverse ginseng Since it is a NMP treatment method using a permeation membrane or a NMP recovery method using vacuum drying, a method for recovering NMP in wastewater using a pervaporation membrane separation process is not known.

Therefore, the present inventor concentrates the specific organic compound from wastewater containing a specific organic compound such as NMP at a concentration not suitable for concentrating and recycling or wastewater treatment, and simultaneously adjusting the concentration of the organic compound in the treated water to the wastewater. The present invention was completed by developing a pervaporation membrane separation process capable of separating at a concentration suitable for treatment.

Patent Document 1 Unexamined Patent Publication No. 10-2012-0093826 Patent Document 2 Unexamined Patent Publication No. 10-2013-0101278 Patent Document 3 Unexamined Patent Publication No. 10-2017-0125729

The present invention has been devised in view of the above problems, and an object of the present invention is to selectively separate a specific organic compound from wastewater containing a specific organic compound such as NMP, and to concentrate the organic compound up to 70.0 to 99.0% by weight. An object of the present invention is to provide a pervaporation membrane separation process that can be concentrated and recycled, and the separated permeate containing organic compounds with a low concentration of 0.5 wt% or less can be treated as it is in a wastewater treatment plant without dilution and separate water treatment.

The present invention for achieving the above object is characterized in that moisture is dehydrated from wastewater containing a specific organic compound by a pervaporation membrane, and the specific organic compound is concentrated to a concentration of 70.0 to 99.0 wt% A pervaporation membrane separation process is provided.

The pervaporation membrane separation process comprises the steps of: (I) supplying a specific organic compound-containing wastewater with an elevated temperature to the pervaporation membrane module; (II) condensing the water permeated by the separation membrane into a liquid phase; (III) transferring the condensed water to a treated water tank or a waste water treatment facility; and (IV) transferring the specific organic compound, wherein the water is separated and concentrated, to a concentration tank or an inlet tank.

The elevated temperature of the specific organic compound-containing wastewater is characterized in that it is maintained at 70 ~ 130 ℃ by a heater.

The supply flow rate of the specific organic compound-containing wastewater supplied to the pervaporation membrane module is 10 times or more of the permeate flow rate.

The concentration of the specific organic compound recovered as a concentrated solution through the pervaporation membrane module is characterized in that 70 ~ 99.9% by weight.

It is characterized in that the concentration of a specific organic compound in the water permeated and dehydrated in step (III) is 0.5 wt% or less.

The specific organic compound is N-methylpyrrolidone (NMP), dimethylformamide (DMF), dimethylacetamide (DMAC), dimethyl sulfoxide (DMSO), isopropyl alcohol (IPA), methanol, ethanol or propanol. characterized.

The pervaporation membrane is characterized in that the zeolite or silicon-based material is attached to the ceramic-based porous support.

According to the pervaporation membrane separation process of the present invention, dehydration from wastewater containing a specific organic compound such as NMP, and selectively separating the specific organic compound can be recycled by concentrating the organic compound to a high concentration of 70.0 to 99.0 wt%. At the same time, wastewater containing organic compounds at a low concentration of 0.5 wt% or less can be treated in an existing wastewater treatment plant without separate dilution and additional water treatment.

1 is a block diagram showing a pervaporation membrane separation process for selectively separating and concentrating a specific organic compound from wastewater containing a specific organic compound according to the present invention;

Hereinafter, according to the present invention, the specific organic compound is concentrated to 70.0-99.0 wt% from wastewater containing a specific organic compound, and at the same time, the concentration of the specific organic compound is separated into a concentration suitable for wastewater treatment. It will be described in detail together with the accompanying drawings.

The present invention provides a pervaporation membrane separation process characterized in that moisture is dehydrated from wastewater containing a specific organic compound by a pervaporation membrane, and the specific organic compound is concentrated to a concentration of 70.0 to 99.0 wt%, wherein the The pervaporation membrane separation process comprises the steps of (I) supplying a specific organic compound-containing wastewater that has been heated to a pervaporation membrane module; (II) condensing the water permeated by the separation membrane into a liquid phase; (III) transferring the condensed water to a treated water tank or a waste water treatment facility; and (IV) transferring the specific organic compound, wherein the water is separated and concentrated, to a concentration tank or an inlet tank.

1 is a block diagram showing a pervaporation membrane separation process for selectively separating and concentrating a specific organic compound from wastewater containing a specific organic compound according to the present invention. Based on the process diagram shown in FIG. 1, the present invention An embodiment will be described.

First, wastewater (solution) containing NMP as a specific organic compound is stored in the NMP wastewater tank 100 . The stored wastewater containing NMP is primarily separated from foreign substances in the line filter 110 , and the wastewater containing NMP transferred by the supply pump 120 is usually heated by a heating means such as the heater 130 . At this time, if the temperature of the wastewater solution containing NMP is less than 70 ℃, the permeation amount of the pervaporation membrane module is too small, and if the temperature exceeds 130 ℃, energy consumption is too large, so the wastewater containing NMP is ) and it is preferable to maintain it at 70 ~ 130 ℃ by increasing the temperature.

Then, the wastewater containing NMP heated to 70 ~ 130 ℃ is supplied to the pervaporation membrane module 150, where it is accompanied by the process of going through the inflow flow meter (140). At this time, the supply flow rate of the wastewater containing NMP supplied to the pervaporation membrane module 150 is preferably controlled to be 10 times or more of the permeate flow rate. If the wastewater containing NMP is supplied to the pervaporation membrane module 150 at 10 times or less, the flow rate of the permeate wastewater passing through the pervaporation membrane module 150 is low, so that separation and concentration are not performed smoothly.

In this way, the wastewater containing NMP supplied to the pervaporation membrane module 150 has a mechanism in which water is selectively dissolved in the separation membrane, diffuses in the separation membrane, and permeates in the vapor phase. This mechanism of action is that one end of the pervaporation membrane module 150 is in contact with the NMP supply wastewater and the other end is in contact with the vapor pressure of the low permeate. The low vapor pressure condition can be made by applying a vacuum or allowing an inert carrier gas to flow. , in general, since a gradient of chemical potential, which is the driving force of the pervaporation membrane separation process, occurs inside the pervaporation membrane, and the material permeates through the membrane, in the present invention, in order to maintain the driving force of the pervaporation membrane separation process A vacuum is maintained by using the vacuum pump 180 .

Next, the vapor-phase permeated water that has passed through the pervaporation membrane module 150 is condensed into a liquid phase in a conventional condenser 170 , and the condensed liquid permeated water passes through the permeate flow meter 200 to the permeate tank 210 ) is transferred to

The NMP wastewater dehydrated by the pervaporation membrane module 150 is transferred to the NMP wastewater tank 100 again, and a series of processes are repeated until it reaches a specific concentration. The NMP of the NMP wastewater tank that has reached a certain concentration is transferred to the concentrated NMP tank 190 , and at this time passes through the line filter 160 to remove any foreign substances that may exist. The concentration of the NMP solution obtained through this pervaporation membrane separation process is concentrated to 70.0-99.0 wt%, so it can be recycled. In addition, wastewater containing NMP at a low concentration of 0.5 wt% or less can be treated in an existing wastewater treatment plant without separate dilution and additional water treatment.

In addition, as the pervaporation membrane used in the separation process of the pervaporation membrane of the embodiment, a zeolite or a silicon-based material may be attached to a ceramic-based porous support, but is not limited thereto.

And in the above embodiment, the organic compound in the wastewater containing a specific organic compound is NMP, but the specific organic compound is dimethylformamide (DMF), dimethylacetamide (DMAC), dimethyl sulfoxide (DMSO) in addition to NMP. , isopropyl alcohol (IPA), methanol, ethanol or propanol.

Hereinafter, specific examples will be described in detail.

(Example 1)

The NMP concentration of the NMP-containing wastewater was fixed at 60 wt %, the feed flow rate was fixed at 1.0 LPM (liter per minute), and the pervaporation membrane separation process was performed while maintaining the temperature of the feed solution at 90 ° C. The water permeability of the permeate solution according to the NMP concentration by the membrane separation process and the average water permeability from the inlet concentration to the concentrated solution were shown.

Feed solution temperature
(℃) NMP concentration of the concentrated solution
(weight%) water permeability
(kg/m ² hr) Average water permeability
(kg/m ² hr) 90 60 4.85 4.85 90 70 3.40 4.27 90 80 2.73 4.25 90 90 2.45 3.89

(Example 2)

The NMP concentration of the NMP-containing wastewater was fixed at 60 wt%, the feed flow rate was set to 2.0 LPM (liter per minute), and the pervaporation membrane separation process was performed while the temperature of the feed solution was maintained at 110 °C. The water permeability of the permeate solution according to the NMP concentration by the membrane separation process and the average water permeability from the inlet concentration to the concentrated solution were shown.

Feed solution temperature
(℃) NMP concentration of the concentrated solution
(weight%) water permeability
(kg/m ² hr) Average water permeability
(kg/m ² hr) 110 60 15.80 15.80 110 70 7.70 12.39 110 80 4.73 10.05 110 90 1.33 6.83

(Example 3)

The IPA concentration of the IPA-containing wastewater was fixed at 50 wt% and the feed flow rate was set to 1.0 LPM (liter per minute), and the pervaporation membrane separation process was performed while maintaining the temperature of the feed solution at 100 ° C. IPA concentration and water permeability according to time by the membrane separation process were shown.

time (hr) 0 2 4 6 8 10 12 14 IPA concentration (wt%) 50 54.4 57.6 67.6 72.4 86.2 98.6 99.6 Average water permeability (kg/m ² hr) - 1.540 1.295 1.110 0.968 1.147 1.112 1.076

As shown in Tables 1 to 3, according to the pervaporation membrane separation process according to Examples 1 to 3 of the present invention, the higher the temperature of the feed solution, the higher the water permeability, and the higher the feed flow rate, the higher the water permeability. it can be seen that Also, in all cases, the NMP and IPA concentrations of the permeate solution were all 0.5 wt% or less, confirming that the permeate solution could be treated in the existing wastewater treatment plant without additional water treatment.

Therefore, according to the pervaporation membrane separation process of the present invention, organic compounds other than NMP can be selectively separated from the wastewater of organic compounds other than NMP and concentrated to 70.0-99.0% by weight or more, and recycled, and at the same time, NMP of low homogeneity of 0.5% by weight or less The organic compound permeation solution exhibits a remarkable effect that it can be treated as it is in the existing wastewater treatment plant without additional dilution and additional water treatment.

As shown in Tables 1 and 2, according to the vapor permeation membrane separation process according to Examples 1 and 2 of the present invention, when the temperature of the feed solution is 100 to 120° C., the concentration of IPA concentrated from the IPA-containing wastewater is 90.0 It was confirmed that IPA can be recycled by showing a high concentration of ~99.9% by weight. In addition, it can be seen that the higher the IPA concentration of the feed solution, the higher the IPA concentration of the concentrated solution and the decrease of the permeate flow rate. On the other hand, it was also confirmed that the permeate solution (permeate water) could be transferred to a wastewater treatment plant as it is for wastewater treatment because the IPA concentration of the permeate solution was only 0.2% by weight in any case regardless of the IPA concentration of the feed solution.

Therefore, according to the vapor permeation membrane separation process of the present invention, dehydration from wastewater containing a specific organic compound such as NMP and selectively separating the specific organic compound can be recycled by concentrating the organic compound to a high concentration of 70.0 to 99.0 wt%. At the same time, wastewater containing organic compounds at a low concentration of 0.5% by weight or less exhibits a remarkable effect that it can be treated as it is in the existing wastewater treatment plant without separate dilution and additional water treatment.

Claims (8)

A pervaporation membrane separation process characterized by dehydrating water from wastewater containing a specific organic compound by a pervaporation membrane, and concentrating the specific organic compound to a concentration of 70.0 to 99.0 wt%. The method of claim 1, wherein the pervaporation membrane separation process comprises the steps of: (I) supplying a specific organic compound-containing wastewater with an elevated temperature to the pervaporation membrane module; (II) condensing the water permeated by the separation membrane into a liquid phase; (III) transferring the condensed water to a treated water tank or a waste water treatment facility; and (IV) transferring the specific organic compound, wherein the water is separated and concentrated, to a concentration tank or an inlet tank. [3] The process of claim 2, wherein the elevated temperature of the wastewater containing a specific organic compound is maintained at 70-130°C by a heater. The process according to claim 2, wherein the supply flow rate of the wastewater containing a specific organic compound supplied to the pervaporation membrane module is 10 times or more of the permeate flow rate. The process according to claim 2, wherein the concentration of a specific organic compound recovered as a concentrated solution through the pervaporation membrane module is 70 to 99.9 wt%. The process according to claim 2, wherein the concentration of a specific organic compound in the water permeated and dehydrated in step (III) is 0.5 wt% or less. [3] The process of claim 2, wherein the pervaporation membrane is formed by attaching a zeolite or a silicon-based material to a ceramic-based porous support. 8. The method according to any one of claims 1 to 7, wherein the specific organic compound is N-methylpyrrolidone (NMP), dimethylformamide (DMF), dimethylacetamide (DMAC), dimethylsulfoxide (DMSO), Pervaporation membrane separation process, characterized in that isopropyl alcohol (IPA), methanol, ethanol or propanol.

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