A method for separating mixed alcohols from industrial wastewater

Abstract

The present invention provides a method for separating mixed alcohols from industrial wastewater, which comprises the following steps: First, the extractant is transported to the first plate at the bottom layer in the extraction tower, and the industrial wastewater is transported to the first plate at the top of the extraction tower. After liquid-liquid extraction separation, an extractant oil-phase solution containing mixed alcohols is obtained at the top of the tower; Then, the extractant oil-phase solution obtained in the above step is sent to the mixed alcohol refining tower. After removing the extractant, a mixed alcohol solution is obtained. The present invention adopts a two-column operation method of liquid-liquid extraction - mixed alcohol refining. At the bottom of the liquid-liquid extraction tower, an aqueous phase with COD < 500 ppm and ammonia nitrogen < 50 ppm, meeting the requirements of open ditch water index, is obtained. At the top of the tower, an oil phase containing mixed alcohols is obtained. The oil phase enters the mixed alcohol refining tower. At the top of the tower, the extractant is obtained and recycled. At the bottom of the tower, a mixed alcohol product with a purity > 99.9% is obtained. Moreover, the process flow is simple, efficient, energy-saving, the wastewater treatment capacity is improved, the recovery rate and purity of alcohols are increased, meeting the characteristics of modern industrial production.

Description

Technical Field

[0001] The invention belongs to the technical field of mixed alcohol extraction, and relates to a method for separating mixed alcohol from industrial waste water, and in particular to a method for separating mixed alcohol from industrial waste water containing mixed alcohol. Background Art

[0002] Mixed alcohol is an important chemical raw material, widely used in various plastics and rubber products, and is also an important raw material in organic synthesis, or an extractant for grease, medicine (such as antibiotics, hormones and vitamins) and spices, an additive for alkyd resin coatings, etc. In the study of industrial wastewater in the chemical industry, the separation of alcohol-water system has always been a hot spot and difficulty. Because the aqueous solution containing a small amount of alcohol, such as direct discharge, will waste organic solvents and cause environmental pollution, it is very necessary to separate and recycle industrial alcohol-containing wastewater. Some related technical solutions are also disclosed in the prior art, such as CN111252977 discloses a process for neutralizing and rectifying high hydrochloric acid mixed alcohol wastewater, but the process has the disadvantages of complex flow, low treatment efficiency, large floor space, large processing energy consumption, and low product recovery rate.

[0003] Therefore, it is necessary to find an efficient, simple and energy-saving separation technology to solve the above-mentioned problems in separating mixed alcohols in process wastewater, increase the yield and purity of alcohols, and meet the development of industrial production. This has become one of the urgent problems to be solved by many front-line researchers in the industry. Summary of the invention

[0004] In view of this, the technical problem to be solved by the present invention is to provide a method for separating mixed alcohols from industrial wastewater, in particular, a method for separating mixed alcohols from industrial wastewater containing mixed alcohols. The present invention adopts a method of liquid-liquid extraction-mixed alcohol refining double tower operation, and obtains a water phase at the bottom of the liquid-liquid extraction tower with COD < 500ppm and ammonia nitrogen < 50ppm, which meets the requirements of open ditch water indicators, and obtains an oil phase containing mixed alcohols at the top of the tower. The oil phase enters the mixed alcohol refining tower, and an extractant is obtained at the top of the tower. The extractant is recycled, and a mixed alcohol product with a purity of > 99.9% is obtained at the bottom of the tower; and the extraction method is simple and easy, with mild conditions, strong controllability, good stability, and is easier to promote and apply in industrial production.

[0005] The present invention provides a method for separating mixed alcohol from industrial wastewater containing mixed alcohol, comprising the following steps:

[0006] 1) The extractant is transported to the first plate at the bottom of the extraction tower, and the industrial wastewater is transported to the first plate at the top of the extraction tower. After liquid-liquid extraction and separation, an extractant oil phase solution containing mixed alcohol is obtained at the top of the tower;

[0007] 2) The extractant oil phase solution obtained in the above step is sent to a mixed alcohol refining tower to remove the extractant to obtain a mixed alcohol solution.

[0008] Preferably, the industrial wastewater containing mixed alcohols includes the alcohol-containing wastewater discharged from the chemical industry;

[0009] The content of mixed alcohols in the industrial wastewater containing mixed alcohols is 3% - 15%;

[0010] The mixed alcohols include multiple of methanol, ethanol, propanol, butanol, pentanol, hexanol, and heptanol.

[0011] Preferably, the industrial wastewater containing mixed alcohols includes one or more of Fischer-Tropsch synthesis waste liquid, waste liquid from phenolic resin production, waste liquid from caprolactam production, methanol-to-olefins wastewater, coal-to-alcohol industrial wastewater, and alcohol-containing wastewater discharged from the chemical industry;

[0012] The extractant includes a mixture of nitrogen-containing compounds and sulfur-containing compounds;

[0013] The mass ratio of the nitrogen-containing compound to the sulfur-containing compound is 1:(1 - 3).

[0014] Preferably, the nitrogen-containing compound includes one or more of dipropylamine, tributylamine, triethylamine, dipentylamine, and isobutyronitrile;

[0015] The sulfur-containing compound includes ethyl sulfide and / or thiophene.

[0016] Preferably, the mass ratio of the extractant to the industrial wastewater is (1 - 5):1;

[0017] The number of trays in the extraction column is 3 - 10.

[0018] Preferably, the temperature of the liquid-liquid extraction is 50 - 90 °C;

[0019] After the liquid-liquid extraction and separation, an aqueous phase is obtained at the bottom of the column.

[0020] Preferably, the COD of the aqueous phase < 500 ppm;

[0021] The ammonia nitrogen of the aqueous phase < 50 ppm.

[0022] Preferably, the specific operation of feeding into the mixed alcohol refining column is to enter the column from the middle of the mixed alcohol refining column;

[0023] The operating pressure of the mixed alcohol refining column is atmospheric pressure;

[0024] The top gas phase temperature of the mixed alcohol refining column is 80 - 90 °C.

[0025] Preferably, the top reflux ratio of the mixed alcohol refining column is 1 - 3;

[0026] The purity of the mixed alcohols in the mixed alcohol solution > 99.9%;

[0027] Preferably, after removing the extractant, a mixed alcohol solution is obtained at the bottom of the tower;

[0028] After removing the extractant, the extractant is obtained at the top of the tower;

[0029] The extractant obtained at the top of the tower is returned to the extractant inlet of the liquid-liquid extraction tower for recycling.

[0030] The present invention provides a method for separating mixed alcohols from industrial wastewater containing mixed alcohols, comprising the following steps: First, the extractant is transported to the first plate at the bottom layer of the extraction tower, and the industrial wastewater is transported to the first plate at the top of the extraction tower. After liquid-liquid extraction separation, an extractant oil-phase solution containing mixed alcohols is obtained at the top of the tower; then, the extractant oil-phase solution obtained in the above step is sent to a mixed alcohol refining tower, and after removing the extractant, a mixed alcohol solution is obtained. Compared with the prior art, for industrial alcohol-containing wastewater, if directly discharged, it will waste organic solvents and cause environmental pollution. The present invention proposes a brand-new extractant and wastewater treatment process. This process route adopts the method of operating two towers of liquid-liquid extraction and mixed alcohol refining. At the bottom of the liquid-liquid extraction tower, an aqueous phase with COD < 500 ppm and ammonia nitrogen < 50 ppm meeting the requirements of open ditch water indicators is obtained. At the top of the tower, an oil phase containing mixed alcohols is obtained. The oil phase enters the mixed alcohol refining tower. At the top of the tower, the extractant is obtained and recycled. At the bottom of the tower, a mixed alcohol product with a purity > 99.9% is obtained.

[0031] The method for separating mixed alcohols provided by the present invention has a simple, efficient, energy-saving process flow, improves the wastewater treatment capacity, increases the recovery rate and purity of alcohols, and meets the characteristics of modern industrial production. BRIEF DESCRIPTION OF THE DRAWINGS

[0032] Figure 1 It is a schematic diagram of the process flow for separating mixed alcohols from industrial wastewater provided by the present invention. DETAILED DESCRIPTION OF THE INVENTION

[0033] In order to further understand the present invention, the preferred implementation modes of the present invention will be described below in conjunction with embodiments. However, it should be understood that these descriptions are only for further explaining the features and advantages of the present invention rather than limiting the claims of the present invention.

[0034] For all raw materials of the present invention, there is no particular limitation on their sources, and they can be purchased on the market or prepared by conventional methods well-known to those skilled in the art.

[0035] For all raw materials of the present invention, there is no particular limitation on their purity. The present invention preferably uses industrial purity or the conventional purity in the field of separating industrial wastewater containing mixed alcohols.

[0036] The present invention provides a method for separating mixed alcohols from industrial wastewater containing mixed alcohols, comprising the following steps:

[0037] 1) Transfer the extractant to the first plate at the bottom layer inside the extraction column, and transfer the industrial wastewater to the first plate at the top of the extraction column. After liquid-liquid extraction separation, an extractant oil-phase solution containing mixed alcohols is obtained at the top of the column.

[0038] 2) Send the extractant oil-phase solution obtained in the above step to the mixed alcohol refining column. After removing the extractant, a mixed alcohol solution is obtained.

[0039] In the present invention, first, the extractant is transferred to the first plate at the bottom layer inside the extraction column (liquid-liquid extraction column), and the industrial wastewater is transferred to the first plate at the top of the extraction column. After liquid-liquid extraction separation, an extractant oil-phase solution containing mixed alcohols is obtained at the top of the column.

[0040] In the present invention, the industrial wastewater containing mixed alcohols preferably includes alcohol-containing wastewater discharged from the chemical industry.

[0041] In the present invention, the content of mixed alcohols in the industrial wastewater containing mixed alcohols is preferably 3% - 15%, more preferably 5% - 13%, and even more preferably 7% - 11%.

[0042] In the present invention, the mixed alcohols preferably include monohydric alcohols, preferably including multiple of methanol, ethanol, propanol, butanol, pentanol, hexanol, and heptanol.

[0043] In the present invention, the industrial wastewater containing mixed alcohols preferably includes one or more of Fischer-Tropsch synthesis waste liquid, waste liquid from phenolic resin production, waste liquid from caprolactam production, methanol-to-olefins wastewater, coal-to-alcohol industrial wastewater, and alcohol-containing wastewater discharged from the chemical industry, and more preferably Fischer-Tropsch synthesis waste liquid, waste liquid from phenolic resin production, waste liquid from caprolactam production, methanol-to-olefins wastewater, coal-to-alcohol industrial wastewater, or alcohol-containing wastewater discharged from the chemical industry.

[0044] In the present invention, the extractant preferably includes a mixture of a nitrogen-containing compound and a sulfur-containing compound.

[0045] In the present invention, the mass ratio of the nitrogen-containing compound to the sulfur-containing compound is preferably 1:(1 - 3), more preferably 1:(1.4 - 2.6), and even more preferably 1:(1.8 - 2.2).

[0046] In the present invention, the nitrogen-containing compound preferably includes one or more of dipropylamine, tributylamine, triethylamine, dipentylamine, and isobutyronitrile, and more preferably dipropylamine, tributylamine, triethylamine, dipentylamine, or isobutyronitrile.

[0047] In the present invention, the sulfur-containing compound preferably includes ethyl sulfide and / or thiophene, and more preferably ethyl sulfide or thiophene.

[0048] In the present invention, the mass ratio of the extractant to the industrial wastewater, i.e., the solvent ratio of the liquid-liquid extraction column, is preferably (1-5):1, more preferably (1.5-4.5):1, still more preferably (2-4):1, and even more preferably (2.5-3.5):1.

[0049] In the present invention, the number of trays of the extraction column is preferably 3-10, more preferably 4-9, still more preferably 5-8, and even more preferably 6-7.

[0050] In the present invention, the temperature of the liquid-liquid extraction is preferably 50-90°C, more preferably 55-85°C, still more preferably 60-80°C, and even more preferably 65-75°C.

[0051] In the present invention, after the liquid-liquid extraction and separation, an aqueous phase is preferably obtained at the bottom of the column.

[0052] In the present invention, the COD of the aqueous phase is preferably <500 ppm, more preferably <450 ppm, and still more preferably <500 ppm.

[0053] In the present invention, the ammonia nitrogen in the aqueous phase is preferably <50 ppm, more preferably <45 ppm, and still more preferably <40 ppm.

[0054] Finally, in the present invention, the extractant oil-phase solution obtained in the above steps is sent to a mixed alcohol refining column, and after removing the extractant, a mixed alcohol solution is obtained.

[0055] In the present invention, the specific preference for sending it to the mixed alcohol refining column is to enter the column from the middle of the mixed alcohol refining column.

[0056] In the present invention, the operating pressure of the mixed alcohol refining column is preferably atmospheric pressure.

[0057] In the present invention, the top gas phase temperature of the mixed alcohol refining column is preferably 80-90°C, more preferably 82-88°C, and still more preferably 84-86°C.

[0058] In the present invention, the top reflux ratio of the mixed alcohol refining column is preferably 1-3, more preferably 1.4-2.6, and still more preferably 1.8-2.2.

[0059] In the present invention, the purity of the mixed alcohol in the mixed alcohol solution is preferably >99.9%, more preferably >99.94%, and still more preferably >99.98%.

[0060] In the present invention, after removing the extractant, a mixed alcohol solution is preferably obtained at the bottom of the column.

[0061] In the present invention, after removing the extractant, the extractant is preferably obtained at the top of the column.

[0062] In the present invention, the extractant obtained at the top of the tower is preferably returned to the extractant inlet of the liquid-liquid extraction tower for recycling.

[0063] In the present invention, after the method for separating mixed alcohols from industrial wastewater provided by the present invention, the finally separated mixed alcohol solution is preferably a monohydric alcohol mixed alcohol solution.

[0064] To complete and refine the overall technical solution of the present invention, better ensure the stable operation of separating mixed alcohols from industrial wastewater, and further improve the separation effect, the method for separating mixed alcohols from industrial wastewater may specifically include the following steps:

[0065] The method for separating mixed alcohols from industrial wastewater includes the following steps:

[0066] (1) Liquid-liquid extraction tower: The extractant is transported to the first plate at the bottom layer inside the tower, and the wastewater is sent to the first plate at the top of the tower for liquid-liquid extraction separation. An extractant oil-phase solution containing mixed alcohols is obtained at the top of the liquid-liquid extraction tower, and an aqueous-phase solution meeting the requirements of the open ditch water index is obtained at the bottom of the tower.

[0067] (2) Mixed alcohol refining tower: The oil-phase solution at the top of the liquid-liquid extraction tower is transported to the middle of the mixed alcohol refining tower to remove the extractant. The extractant is obtained at the top of the tower and returned to the extractant inlet of the liquid-liquid extraction tower for recycling. The refined mixed alcohol solution is obtained at the bottom of the tower, with a purity greater than 99.9%.

[0068] Specifically, the extractant is a mixture of a nitrogen-containing compound and a sulfur-containing compound.

[0069] Specifically, the nitrogen-containing compound is one or more of dipropylamine, tributylamine, triethylamine, dipentylamine, and isobutyronitrile.

[0070] Specifically, the sulfur-containing compound is one or two of ethyl sulfide and thiophene.

[0071] Specifically, the mass ratio of the nitrogen-containing compound to the sulfur-containing compound is 1:(1 - 3).

[0072] Specifically, the solvent ratio of the liquid-liquid extraction tower is 1 - 5;

[0073] Specifically, the temperature of the liquid-liquid extraction tower is 50 - 90 °C;

[0074] Specifically, the content of mixed alcohols in the wastewater is 3 - 15%;

[0075] Specifically, the operating pressure of the mixed alcohol refining tower is atmospheric pressure, and the gas-phase temperature at the top of the tower is 80 - 90 °C;

[0076] Specifically, the operating pressure of the mixed alcohol refining tower is atmospheric pressure, and the reflux ratio at the top of the tower is 1 - 3.

[0077] Furthermore,

[0078] The specific technical solution of the present invention is as follows:

[0079] In the method for separating mixed alcohols from industrial wastewater provided by the present invention:

[0080] (1) Liquid-liquid extraction tower: The extractant is transported to the first plate at the bottom layer inside the tower, and the wastewater is sent to the first plate at the top of the tower for liquid-liquid extraction separation. By utilizing the solubility difference of the mixed alcohols in the wastewater between the extractant and water, the separation purpose is achieved.

[0081] An extractant oil-phase solution containing mixed alcohols is obtained at the top of the liquid-liquid extraction tower, and an aqueous-phase solution meeting the requirements of the open-channel water index is obtained at the bottom of the tower.

[0082] (2) Mixed alcohol refining tower: The oil-phase solution at the top of the liquid-liquid extraction tower is transported to the middle part of the mixed alcohol refining tower to remove the extractant. The extractant is obtained at the top of the tower and returned to the extractant inlet of the liquid-liquid extraction tower for recycling. The refined mixed alcohol solution is obtained at the bottom of the tower, and the purity is greater than 99.9%.

[0083] Specifically, the extractant is a mixture of a nitrogen-containing compound and a sulfur-containing compound.

[0084] Specifically, the nitrogen-containing compound is dipropylamine, tributylamine, triethylamine, dipentylamine, isobutyronitrile.

[0085] Specifically, the sulfur-containing compound is ethyl sulfide, thiophene.

[0086] Specifically, the mass ratio of the nitrogen-containing compound to the sulfur-containing compound is 1:(1 - 3).

[0087] In order to obtain better technical effects, the solvent ratio of the liquid-liquid extraction tower is 1 - 5;

[0088] In order to obtain better technical effects, the temperature of the liquid-liquid extraction tower is 50 - 90 °C;

[0089] In order to obtain better technical effects, the content of mixed alcohols in the wastewater is 3 - 15%;

[0090] In order to obtain better technical effects, the operating pressure of the mixed alcohol refining tower is normal pressure, and the gas-phase temperature at the top of the tower is 80 - 90 °C;

[0091] In order to obtain better technical effects, the operating pressure of the mixed alcohol refining tower is normal pressure, and the reflux ratio at the top of the tower is 1 - 3.

[0092] See Figure 1 , Figure 1 which is a schematic process flow diagram for separating mixed alcohols from industrial wastewater provided by the present invention.

[0093] The above content of the present invention provides a method for separating mixed alcohols from industrial wastewater containing mixed alcohols. The present invention proposes a brand-new extractant and wastewater treatment process. This process route adopts the method of liquid-liquid extraction - two-column operation for refining mixed alcohols. The aqueous phase with COD < 500 ppm and ammonia nitrogen < 50 ppm that meets the requirements of open ditch water index is obtained at the bottom of the liquid-liquid extraction column, and the oil phase containing mixed alcohols is obtained at the top of the column. The oil phase enters the mixed alcohol refining column. The extractant is obtained at the top of the column and recycled, and the mixed alcohol product with a purity > 99.9% is obtained at the bottom of the column.

[0094] The method for separating mixed alcohols provided by the present invention has a simple, efficient, energy-saving process flow, improves the wastewater treatment capacity, increases the yield and purity of alcohols, and meets the characteristics of modern industrial production.

[0095] To further illustrate the present invention, the following describes in detail a method for separating mixed alcohols from industrial wastewater containing mixed alcohols provided by the present invention in conjunction with embodiments. However, it should be understood that these embodiments are implemented on the premise of the technical solution of the present invention, and detailed implementation manners and specific operation processes are given. It is only to further illustrate the features and advantages of the present invention, rather than a limitation on the claims of the present invention. The protection scope of the present invention is not limited to the following embodiments.

[0096] All the contents involved below in the present invention are mass fractions.

[0097] Example 1

[0098] The method for separating mixed alcohols from industrial wastewater is as follows:

[0099] The extractant (dipropylamine: ethyl sulfide is 1:1) is transported to the first plate at the bottom layer in the liquid-liquid extraction column, and the wastewater containing 5% of mixed alcohols is transported to the first plate at the top of the column. Liquid-liquid extraction separation is carried out according to a solvent ratio of 2. The temperature of the extraction column is maintained at 80 °C. Utilizing the solubility difference of mixed alcohols in the wastewater between the extractant and water, the extractant solution containing mixed alcohols is obtained at the top of the liquid-liquid extraction column. After detection, an aqueous solution with COD of 200 ppm and ammonia nitrogen of 10 ppm is obtained at the bottom of the column. The extractant solution at the top of the liquid-liquid extraction column is transported to the middle part of the mixed alcohol refining column to remove the extractant. The extractant is returned to the extractant inlet of the liquid-liquid extraction column for recycling. The temperature of the gas phase at the top of the column is controlled at 82 °C, the reflux ratio is 2, and the refined mixed alcohol solution with a purity of 99.97% is obtained at the bottom of the column.

[0100] Example 2

[0101] The method for separating mixed alcohols from industrial wastewater is as follows:

[0102] Transfer the extractant (tributylamine: ethyl sulfide = 1:2) to the first plate at the bottommost layer in the liquid-liquid extraction column, and transfer the mixed alcohol wastewater containing 10% to the first plate at the top of the column. Conduct liquid-liquid extraction separation according to a solvent ratio of 1, keep the temperature of the extraction column at 85°C. Utilize the solubility difference of the mixed alcohol in the wastewater between the extractant and water. An extractant solution containing the mixed alcohol is obtained at the top of the liquid-liquid extraction column. After detection, an aqueous solution with a COD of 80 ppm and ammonia nitrogen of 5 ppm is obtained at the bottom of the column. Transfer the extractant solution at the top of the liquid-liquid extraction column to the middle part of the mixed alcohol refining column to remove the extractant. The extractant is returned to the extractant inlet of the liquid-liquid extraction column for recycling. Control the gas phase temperature at the top of the column to be 85°C and the reflux ratio to be 3. The refined mixed alcohol solution is obtained at the bottom of the column with a purity of 99.99%.

[0103] Example 3

[0104] A method for separating mixed alcohol from industrial wastewater, the specific steps are as follows:

[0105] Transfer the extractant (triethylamine: ethyl sulfide = 1:3) to the first plate at the bottommost layer in the liquid-liquid extraction column, and transfer the mixed alcohol wastewater containing 15% to the first plate at the top of the column. Conduct liquid-liquid extraction separation according to a solvent ratio of 4, keep the temperature of the extraction column at 50°C. Utilize the solubility difference of the mixed alcohol in the wastewater between the extractant and water. An extractant solution containing the mixed alcohol is obtained at the top of the liquid-liquid extraction column. After detection, an aqueous solution with a COD of 250 ppm and ammonia nitrogen of 13 ppm is obtained at the bottom of the column. Transfer the extractant solution at the top of the liquid-liquid extraction column to the middle part of the mixed alcohol refining column to remove the extractant. The extractant is returned to the extractant inlet of the liquid-liquid extraction column for recycling. Control the gas phase temperature at the top of the column to be 90°C and the reflux ratio to be 1. The refined mixed alcohol solution is obtained at the bottom of the column with a purity of 99.92%.

[0106] Example 4

[0107] A method for separating mixed alcohol from industrial wastewater, the specific steps are as follows:

[0108] Transfer the extractant (dipentylamine: thiophene = 1:1) to the first plate at the bottommost layer in the liquid-liquid extraction column, and transfer the mixed alcohol wastewater containing 3% to the first plate at the top of the column. Conduct liquid-liquid extraction separation according to a solvent ratio of 5, keep the temperature of the extraction column at 90°C. Utilize the solubility difference of the mixed alcohol in the wastewater between the extractant and water. An extractant solution containing the mixed alcohol is obtained at the top of the liquid-liquid extraction column. After detection, an aqueous solution with a COD of 150 ppm and ammonia nitrogen of 9 ppm is obtained at the bottom of the column. Transfer the extractant solution at the top of the liquid-liquid extraction column to the middle part of the mixed alcohol refining column to remove the extractant. The extractant is returned to the extractant inlet of the liquid-liquid extraction column for recycling. Control the gas phase temperature at the top of the column to be 80°C and the reflux ratio to be 2. The refined mixed alcohol solution is obtained at the bottom of the column with a purity of 99.95%.

[0109] Example 5

[0110] The method for separating mixed alcohol from industrial wastewater, the specific steps are as follows:

[0111] The extractant (isobutyronitrile: thiophene is 1:3) is transported to the first plate at the bottom of the liquid-liquid extraction tower, and the wastewater containing 6% of mixed alcohol is transported to the first plate at the top of the tower. Liquid-liquid extraction separation is performed according to a solvent ratio of 3. The temperature of the extraction tower is kept at 85°C. The solubility difference of mixed alcohol in the wastewater in the extractant and water is used to obtain an extractant solution containing mixed alcohol at the top of the liquid-liquid extraction tower. After testing, an aqueous phase solution with a COD of 100ppm and ammonia nitrogen of 7ppm is obtained at the bottom of the tower. The extractant solution at the top of the liquid-liquid extraction tower is transported to the middle of the mixed alcohol refining tower, the extractant is removed, and the extractant is returned to the extractant inlet of the liquid-liquid extraction tower for recycling. The gas phase temperature at the top of the tower is controlled to be 88°C, the reflux ratio is 3, and the bottom of the tower is a refined mixed alcohol solution with a purity of 99.98%.

[0112] The above is a detailed introduction to a method for separating mixed alcohols from industrial wastewater provided by the present invention. Specific examples are used herein to illustrate the principles and implementation methods of the present invention. The description of the above embodiments is only used to help understand the method and its core ideas of the present invention, including the best mode, and also enables any technician in the field to practice the present invention, including manufacturing and using any device or system, and implementing any combined method. It should be pointed out that for ordinary technicians in this technical field, without departing from the principle of the present invention, the present invention can also be improved and modified in several ways, and these improvements and modifications also fall within the scope of protection of the claims of the present invention. The scope of patent protection of the present invention is defined by the claims and may include other embodiments that can be thought of by those skilled in the art. If these other embodiments have structural elements similar to the textual expression of the claims, or if they include equivalent structural elements that are not substantially different from the textual expression of the claims, then these other embodiments should also be included in the scope of the claims.

Claims

1. A method for separating mixed alcohols from industrial wastewater containing ambiguous alcohols, characterized in that, It includes the following steps: 1) Feed the extractant to the first plate at the bottom layer in the extraction column, and feed the industrial wastewater to the first plate at the top of the extraction column. After liquid-liquid extraction separation, an extractant oil-phase solution containing mixed alcohols is obtained at the top of the column; The extractant includes a mixture of a nitrogen-containing compound and a sulfur-containing compound; The mass ratio of the nitrogen-containing compound to the sulfur-containing compound is 1:(1-3); The nitrogen-containing compound includes one or more of dipropylamine, tributylamine, triethylamine, dipentylamine, and isobutyronitrile; The sulfur-containing compound includes ethyl sulfide and / or thiophene; 2) Feed the extractant oil-phase solution obtained in the above step to the mixed alcohol refining column. After removing the extractant, a mixed alcohol solution is obtained.

2. The method according to claim 1, wherein The industrial wastewater containing mixed alcohols includes alcohol-containing wastewater discharged from the chemical industry; The content of mixed alcohols in the industrial wastewater containing mixed alcohols is 3%-15%; The mixed alcohols include multiple of methanol, ethanol, propanol, butanol, pentanol, hexanol, and heptanol; 3. The method according to claim 1, wherein The industrial wastewater containing mixed alcohols includes one or more of Fischer-Tropsch synthesis waste liquid, waste liquid from phenolic resin production, waste liquid from caprolactam production, methanol-to-olefins wastewater, coal-to-alcohol industrial wastewater, and alcohol-containing wastewater discharged from the chemical industry; 4. The method according to claim 1, wherein The mass ratio of the extractant to the industrial wastewater is (1-5):1; 5. The method according to claim 1, wherein The number of trays in the extraction column is 3-10; 6. The method according to claim 1, wherein The temperature of the liquid-liquid extraction is 50-90°C; After the liquid-liquid extraction separation, an aqueous phase is obtained at the bottom of the column; 7. The method according to claim 6, wherein The COD of the aqueous phase < 500 ppm; The ammonia nitrogen of the aqueous phase < 50 ppm; 8. The method according to claim 1, wherein The feeding to the mixed alcohol refining column is specifically from the middle of the mixed alcohol refining column; The operating pressure of the mixed alcohol refining column is atmospheric pressure; The gas-phase temperature at the top of the mixed alcohol refining column is 80-90°C; 9. The method according to claim 1, characterized in that, The reflux ratio at the top of the mixed alcohol refining column is 1-3; The purity of the mixed alcohols in the mixed alcohol solution > 99.9%; 10. The method according to claim 1, wherein After removing the extractant, a mixed alcohol solution is obtained at the bottom of the column; After removing the extractant, the extractant is obtained at the top of the column; The extractant obtained at the top is returned to the extractant inlet of the liquid-liquid extraction column for recycling.

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