Method for treating organic waste salt through deep eutectic solvent extraction and application of method

Abstract

The invention belongs to the technical field of wastewater treatment, and particularly relates to a method for treating organic waste salt through deep eutectic solvent extraction and application thereof.The method comprises the steps that a hydrogen bond donor and a hydrogen bond acceptor are prepared through ultrasonic-assisted heating, and the deep eutectic solvent is prepared; performing ultrasonic-assisted mixing on the deep-eutectic solvent and the organic waste salt to prepare a mixed solution; carrying out solid-liquid separation on the mixed solution to obtain wet salt and a solvent; and fully washing the wet salt, and collecting the washing liquid and the salt. The method provided by the invention has the characteristics of green and safe whole process, simple process, high organic matter removal rate and sustainable circulation, and provides an innovative solution for pretreatment and recycling of industrial organic waste salt.

Description

TECHNICAL FIELD

[0001] The application belongs to the technical field of wastewater treatment, and particularly relates to a method for treating organic waste salt by using a deep eutectic solvent and application thereof. BACKGROUND

[0002] At present, in the high-pollution emission industries such as pharmaceutical, petrochemical, printing and dyeing, and coal chemical industry, the industrial organic waste salt formed after the evaporation and concentration of high-concentration salt-containing organic wastewater is rich in polycyclic aromatic hydrocarbons, halogenated hydrocarbons and other carcinogenic organic pollutants, which poses a systematic threat to the ecological environment. The persistent organic pollutants (POPs) in such waste salt can produce biological cumulative effect through soil leaching and groundwater migration, and the ecological toxicity and carcinogenic risk index thereof are significantly higher than the safety threshold.

[0003] At present, the methods for treating organic waste salt mainly include high-temperature pyrolysis, salt washing, extraction, and chemical oxidation. In the salt washing method, the washing agent is saturated brine, which is simple to operate, but the multi-stage washing increases the water consumption and produces pollutant wastewater, and is not suitable for waste salt with complex components. In the extraction method, the extractant is ethanol or methanol, which has low treatment energy consumption, but the extractant is volatile and flammable, which can easily cause secondary pollution and increase the safety risk, and the removal effect of low-concentration or multi-component mixed organic matter is poor. Therefore, it is urgent to develop a new type of green, safe, and cyclic waste salt treatment technology which can efficiently treat low-concentration or multi-component high-content organic matter.

[0004] Deep eutectic solvent (DES) is currently widely used in the fields of biological and food extraction, environmental governance, electrochemistry, material science, and chemical synthesis and catalysis. In biological and food extraction, the effect of extracting target products is very good, and in the field of environmental governance, it is mainly used in the fields of oxidative desulfurization and waste gas absorption. However, there is a technical gap in the application of waste salt treatment. In the current Chinese patent applications, the waste salt treatment technologies mainly adopt high-temperature pyrolysis, catalytic oxidation, and single solvent washing method, and there is no patent method for pretreating organic waste salt by using deep eutectic solvent. SUMMARY

[0005] The application mainly provides a high-efficiency and stable deep eutectic solvent, a method for cyclic and sustainable extraction treatment of organic waste salt by using the deep eutectic solvent, and application thereof, so as to overcome the problems of poor removal effect of low-concentration or multi-component mixed organic matter, easy secondary pollution, and large safety risk in the prior art. The technical scheme is as follows.

[0006] A method for treating organic waste salt by using a deep eutectic solvent, a method for treating organic waste salt by using the deep eutectic solvent, and application thereof, so as to overcome the problems of poor removal effect of low-concentration or multi-component mixed organic matter, easy secondary pollution, and large safety risk in the prior art. The technical scheme is as follows.

[0007] Further, the hydrogen bond acceptor is a quaternary ammonium salt; the hydrogen bond donor is an organic nitrogen compound or a polyol.

[0008] Further, the hydrogen bond acceptor includes one or more of choline chloride, tetrabutylammonium chloride or quaternary ammonium polyamine.

[0009] Further, the organic nitrogen compound includes one or more of urea, monoethanolamine or diethanolammonium; the polyol includes one or more of glycerol, ethylene glycol or propylene glycol.

[0010] Further, the molar ratio of the hydrogen bond acceptor to the hydrogen bond donor is 1:1-5; the mass ratio of the organic waste salt to the eutectic solvent is 1:1-5.

[0011] Further, the ultrasonic power is 100-200 W; the ultrasonic frequency is 20-30 kHz; the ultrasonic time is 10-20 min; the preparation temperature is 50-80℃; the preparation time is 20-40 min; the mixing temperature is 25-60℃; and the mixing time is 20-35 min.

[0012] Further, the wet salt is dispersed in ethanol at a mass ratio of 1:1-1.5, and the salt and washing liquid are separated and collected.

[0013] Further, the solvent and the washing liquid are purified, and the eutectic solvent is recovered.

[0014] Further, the purification is filtering the solvent and the washing liquid, and then dehydrating; the eutectic solvent is recovered by distillation under reduced pressure at 75-85℃.

[0015] The application of the above-mentioned method for treating organic waste salt by eutectic solvent extraction in wastewater treatment, the organic matter in the organic waste salt is one or more.

[0016] By using the above scheme, the method has the following advantages:

[0017] 1. The quaternary ammonium cation (R4N + ) carries a permanent positive charge, and through direct electrostatic attraction of anion pollutants such as sulfate, nitrate, and organic sulfonate in the waste salt, the anions are pulled close to the DES phase interface, realizing electrostatic enrichment; the quaternary ammonium group can effectively remove anionic dyes through charge neutralization; and the ion pair formed in the quaternary ammonium compound can efficiently adsorb halogen ions through solvent polarity.

[0018] 2、Quaternary ammonium cation and organic nitrogen compounds or polyol compounds build a three-dimensional hydrogen bond network, destroy the combination of pollutants and salt matrix, enhance the solubility of oxygen-containing anions such as phosphate, carboxylate, etc., and the hydrophilic hydrogen bond donor forms strong hydrogen bonds with oxygen-containing anions through oxygen atoms, and the hydrogen bond effect and the electrostatic effect of quaternary ammonium cation synergistically remove oxygen-containing anions.

[0019] 3、The eutectic solvent of the present application shows high efficient dissolution and removal ability to low concentration or high concentration multi-component mixed organic matter, the quaternary ammonium cation can combine with anions in organic waste salt through electrostatic effect, destroy the ionic bond between waste salt and organic matter, release organic matter, and the anion as a strong hydrogen bond acceptor enhances the polarity of the solvent, thereby improving the solubility of the organic matter; organic nitrogen compounds such as monoethanolamine and diethanolamine contain amino and hydroxyl groups, which can complex with anions and enhance removal.

[0020] 4、Medium and long chain quaternary ammonium salts such as tetraethylammonium chloride can simultaneously adsorb anion pollutants through electrostatic effect and adsorb halogenated hydrocarbons through hydrophobic chains, reducing coexisting interference; the polar structure of quaternary ammonium salt compounds makes the eutectic solvent have high dielectric constant, which is suitable for dissolving polar or moderately polar organic matter.

[0021] 5、The eutectic solvent of the present application is low in price and widely available, the eutectic solvent with it as a hydrogen bond acceptor component is easy to prepare and low in cost, low in volatility, low in loss and low in toxicity, most of the components are biodegradable, and can be recycled after recovery.

[0022] 6、When preparing the eutectic solvent and treating waste salt, ultrasonic waves are introduced to improve the configuration efficiency and stability of the eutectic solvent by cavitation effect, so that the eutectic solvent is fully mixed with organic waste salt, the organic matter is desorbed from the salt crystal lattice, penetrates the waste salt crystal lattice, destroys the crystal lattice structure, releases the organic matter and impurities, and at the same time retains the main components of the salt.

[0023] 7、The eutectic solvent of the present application is low in toxicity, low in volatility, low in flammability and biodegradable, avoiding secondary pollution and safety risks of traditional solvents. The method of the present application treats organic pollutants and inorganic impurities in organic waste salt by a system, realizes the harmless and resource utilization of the salt, and has significant environmental protection significance and resource value. BRIEF DESCRIPTION OF DRAWINGS

[0024] Figure 1 It is a comparison chart before and after the treatment of three kinds of organic waste salt in Example 1;

[0025] Figure 2 It is the TOC removal rate of the eutectic solvent of each example on three kinds of waste salt;

[0026] Figure 3 It is the TOC removal rate of the eutectic solvent of each control experiment on three kinds of waste salt;

[0027] Figure 4 Flow chart for preparation of deep eutectic solvent;

[0028] Figure 5 Flow chart for treatment of organic waste salt by deep eutectic solvent. DETAILED DESCRIPTION

[0029] The technical solutions in the embodiments of the present application will be clearly and completely described below. Obviously, the described embodiments are only a part of the embodiments of the present application, rather than all the embodiments. Based on the embodiments in the present application, all the other embodiments obtained by those skilled in the art without creative work fall within the protection scope of the present application.

[0030] The properties of the organic waste salt in the following embodiments and the control experiment are shown in Table 1:

[0031] Table 1:

[0032]

[0033] Embodiment 1: (1) Choline chloride and urea were mixed in a reactor according to a molar ratio of 1:4, and then ultrasonic treatment was performed at a power of 150 W and a frequency of 20 kHz for 20 min, followed by constant temperature water bath at 60℃ and stirring at a speed of 300 r / min for 20 min, to obtain a deep eutectic solvent;

[0034] (2) Organic waste salt 1 and the deep eutectic solvent were mixed in a reactor according to a mass ratio of 1:4, and then ultrasonic treatment was performed at a power of 200 W and a frequency of 25 kHz for 20 min, followed by constant temperature water bath at 40℃ and stirring at a speed of 300 r / min for 20 min, to obtain a mixed solution; the mixed solution was centrifuged at 4000 r / min for 5 min, and then the solvent and wet salt were separated;

[0035] (3) 1.25 times of the mass of the waste salt of ethanol was added to the wet salt, and stirring was performed at a speed of 300 r / min for 10 min; the washing solution and the salt were separated after centrifugation at 4000 r / min for 5 min;

[0036] (4) The obtained salt was repeatedly washed according to step (3) for 2 times, and the finally obtained salt was placed in a blast drying oven at 80℃ for drying for 1 h, to obtain a salt with most of the organic matter and impurities removed.

[0037] (5) The solvent and the washing solution after multiple washings were filtered through a 0.22 μm filter membrane and dehydrated by urea, and then the deep eutectic solvent was recovered by distillation under reduced pressure under the conditions of a water bath at 75-85℃ and a pressure of 0.02 MPa.

[0038] Organic waste salt 2 and organic waste salt 3 were treated by the method of treating organic waste salt 1 in Example 1. The comparison of the treated organic waste salt 1-3 with the original salt is shown in Table 1. Figure 1 As shown in the table, it can be seen from the table that the color of the treated organic waste salt is lighter than that of the original salt, which indicates that most of the colored impurities can be removed by the method of the present application, and the effect is significant.

[0039] Example 2: The difference from Example 1 is that:

[0040] (1) Choline chloride and glycerol were mixed in a reactor at a molar ratio of 1:2, and were ultrasonicated at a power of 180 W and a frequency of 25 kHz for 10 min, and then were stirred at a speed of 400 r / min in a constant temperature water bath at 50°C for 20 min to obtain a eutectic solvent;

[0041] (2) Organic waste salt 1 and the eutectic solvent were mixed in a reactor at a mass ratio of 1:3, and were ultrasonicated at a power of 180 W and a frequency of 25 kHz for 10 min, and then were stirred at a speed of 400 r / min in a constant temperature water bath at 50°C for 20 min to obtain a mixed solution; the mixed solution was centrifuged at 3500 r / min for 10 min to separate the solvent and the wet salt;

[0042] (3) 1.5 times the mass of the waste salt was added to the wet salt, and was stirred at a speed of 400 r / min for 5 min; after centrifugation at 3500 r / min for 10 min, the washing solution and the salt were separated.

[0043] Organic waste salt 2 and organic waste salt 3 were treated by the method of treating organic waste salt 1 in Example 2.

[0044] Example 3: The difference from Example 1 is that:

[0045] (1) Choline chloride and ethylene glycol were mixed in a reactor at a molar ratio of 1:5, and were ultrasonicated at a power of 180 W and a frequency of 30 kHz for 20 min, and then were stirred at a speed of 200 r / min in a constant temperature water bath at 80°C for 40 min to obtain a eutectic solvent;

[0046] (2) Organic waste salt 1 and the eutectic solvent were mixed in a reactor at a mass ratio of 1:2, and were ultrasonicated at a power of 180 W and a frequency of 30 kHz for 20 min, and then were stirred at a speed of 200 r / min in a constant temperature water bath at 80°C for 40 min to obtain a mixed solution; the mixed solution was centrifuged at 4500 r / min for 7 min to separate the solvent and the wet salt;

[0047] (3) Add 1.2 times the mass of the waste salt to the wet salt, and stir at 200 r / min for 10 min; after centrifugation at 4500 r / min for 7 min, the washing liquid and the salt are separated.

[0048] Organic waste salt 2 and organic waste salt 3 are treated according to the method of Example 3 of treating organic waste salt 1.

[0049] Example 4: The difference from Example 1 is that:

[0050] (1) Choline chloride and diethanolamine are mixed in a reactor according to a molar ratio of 1:1.5, ultrasonic treatment is performed at a power of 200 W and a frequency of 25 kHz for 15 min, then constant temperature water bath at 80°C, stirring at a speed of 400 r / min for 30 min, to obtain a deep eutectic solvent;

[0051] (2) Organic waste salt 1 and the deep eutectic solvent are mixed in a reactor according to a mass ratio of 1:4, ultrasonic treatment is performed at a power of 200 W and a frequency of 25 kHz for 15 min, then constant temperature water bath at 80°C, stirring at a speed of 400 r / min for 35 min, to obtain a mixed liquid; after centrifugation of the mixed liquid at 5000 r / min for 6 min, the solvent and the wet salt are separated;

[0052] (3) Add 1.4 times the mass of the waste salt to the wet salt, and stir at 400 r / min for 8 min; after centrifugation at 5000 r / min for 6 min, the washing liquid and the salt are separated.

[0053] Organic waste salt 2 and organic waste salt 3 are treated according to the method of Example 4 of treating organic waste salt 1.

[0054] Example 5: The difference from Example 1 is that:

[0055] (1) Tetrabutylammonium chloride and ethylene glycol are mixed in a reactor according to a molar ratio of 1:3, ultrasonic treatment is performed at a power of 125 W and a frequency of 20 kHz for 10 min, then constant temperature water bath at 65°C, stirring at a speed of 350 r / min for 25 min, to obtain a deep eutectic solvent;

[0056] (2) Organic waste salt 1 and the deep eutectic solvent are mixed in a reactor according to a mass ratio of 1:1, ultrasonic treatment is performed at a power of 200 W and a frequency of 20 kHz for 10 min, then constant temperature water bath at 65°C, stirring at a speed of 350 r / min for 25 min, to obtain a mixed liquid; after centrifugation of the mixed liquid at 4000 r / min for 5 min, the solvent and the wet salt are separated;

[0057] (3) Add 1.35 times the mass of waste salt ethanol to the wet salt and stir at 350 r / min for 5 min; centrifuge at 4000 r / min for 5 min to separate the washing liquid and salt.

[0058] Organic waste salt 2 and organic waste salt 3 were treated according to the method of Example 5 for treating organic waste salt 1.

[0059] Example 6: The difference from Example 1 is that:

[0060] (1) A quaternized polyamine and monoethanolamine were mixed in a reactor at a molar ratio of 1:1, ultrasonicated for 20 min at a power of 100 W and a frequency of 20 kHz, and then stirred in a constant temperature water bath at 60°C and a speed of 300 rpm for 30 min to obtain a deep eutectic solvent;

[0061] (2) The organic waste salt 1 and the low eutectic solvent were mixed in a reactor at a mass ratio of 1:2, and ultrasonicated for 20 minutes at a power of 100 W and a frequency of 20 kHz, and then stirred at a speed of 300 r / min for 20 minutes in a constant temperature water bath at 40°C to obtain a mixed solution; the mixed solution was centrifuged at 4000 r / min for 5 minutes to separate the solvent and wet salt;

[0062] (3) Add 1.25 times the mass of waste salt ethanol to the wet salt and stir at 300 r / min for 10 min; centrifuge at 4000 r / min for 5 min to separate the washing liquid and salt.

[0063] Organic waste salt 2 and organic waste salt 3 were treated according to the method of Example 5 for treating organic waste salt 1.

[0064] Control experiment 1: The difference from Example 1 is:

[0065] (1) Choline chloride and urea were mixed in a reactor at a molar ratio of 1:4, and then placed in a constant temperature water bath at 60°C and stirred at a speed of 300 r / min for 20 min to obtain a deep eutectic solvent;

[0066] (2) The organic waste salt 1 and the low eutectic solvent were mixed in a reactor in a mass ratio of 1:4, and then stirred at a speed of 300 r / min for 20 min in a constant temperature water bath at 40°C to obtain a mixed solution; the mixed solution was centrifuged at 4000 r / min for 5 min to separate the solvent and wet salt.

[0067] Organic waste salt 2 and organic waste salt 3 were treated according to the method of control experiment 1 for treating organic waste salt 1.

[0068] Control experiment 2: The difference from Example 1 is:

[0069] (1) Choline chloride and glycerol were mixed in a reactor at a molar ratio of 1:2, and ultrasonicated for 30 min at a power of 80 W and a frequency of 20 kHz, and then placed in a constant temperature water bath at 40°C and stirred at a speed of 400 rpm for 20 min to obtain a deep eutectic solvent;

[0070] (2) The organic waste salt 1 and the low eutectic solvent were mixed in a reactor in a mass ratio of 1:3, ultrasonicated for 30 min at a power of 80 W and a frequency of 20 kHz, and then stirred at a speed of 400 r / min for 20 min in a constant temperature water bath at 40°C to obtain a mixed solution; the mixed solution was centrifuged at 3500 r / min for 10 min to separate the solvent and wet salt.

[0071] Organic waste salt 2 and organic waste salt 3 were treated according to the method of control experiment 2 for treating organic waste salt 1.

[0072] Control experiment 3: The difference from Example 1 is:

[0073] (1) Choline chloride and ethylene glycol were mixed in a reactor at a molar ratio of 1:5, and then placed in a constant temperature water bath at 80°C and stirred at a speed of 200 r / min for 40 min to obtain a deep eutectic solvent;

[0074] (2) The organic waste salt 1 and the low eutectic solvent were mixed in a reactor in a mass ratio of 1:2, and then stirred in a constant temperature water bath at 80°C at a speed of 200 r / min for 40 minutes to obtain a mixed solution; the mixed solution was centrifuged at 4500 r / min for 7 minutes to separate the solvent and wet salt.

[0075] Organic waste salt 2 and organic waste salt 3 were treated according to the method of control experiment 3 for treating organic waste salt 1.

[0076] Control experiment 4: The difference from Example 1 is:

[0077] (1) Choline chloride and diethanolamine were mixed in a reactor at a molar ratio of 1:1.5, and then placed in a constant temperature water bath at 80°C and stirred at a speed of 400 r / min for 30 min to obtain a deep eutectic solvent;

[0078] (2) The organic waste salt 1 and the low eutectic solvent were mixed in a reactor in a mass ratio of 1:4, and then stirred at a speed of 400 r / min for 35 min in a constant temperature water bath at 80°C to obtain a mixed solution; the mixed solution was centrifuged at 5000 r / min for 6 min to separate the solvent and wet salt.

[0079] Organic waste salt 2 and organic waste salt 3 were treated according to the method of control experiment 4 for treating organic waste salt 1.

[0080] Control experiment 5: The difference from Example 1 is:

[0081] (1) Tetra-n-butylammonium chloride and ethylene glycol were mixed in a reactor at a molar ratio of 1:3, and then ultrasonic treatment was performed at a power of 300 W and a frequency of 20 kHz for 10 min, followed by constant temperature water bath at 65 °C and stirring at a speed of 350 r / min for 25 min to obtain the deep eutectic solvent;

[0082] (2) Organic waste salt 1 and the deep eutectic solvent were mixed in a reactor at a mass ratio of 1:1, followed by constant temperature water bath at 65 °C and stirring at a speed of 350 r / min for 25 min to obtain a mixed solution; the mixed solution was centrifuged at 4000 r / min for 5 min, and then the solvent and wet salt were separated.

[0083] Organic waste salts 2 and 3 were treated according to the method of the control experiment 5 for treating organic waste salt 1.

[0084] Control experiment 6: the difference from Example 1 is that:

[0085] (1) Quaternary ammonium polyamine and monoethanolamine were mixed in a reactor at a molar ratio of 1:1, followed by constant temperature water bath at 60 °C and stirring at a speed of 300 r / min for 30 min to obtain the deep eutectic solvent;

[0086] (2) Organic waste salt 1 and the deep eutectic solvent were mixed in a reactor at a mass ratio of 1:2, followed by constant temperature water bath at 40 °C and stirring at a speed of 300 r / min for 20 min to obtain a mixed solution; the mixed solution was centrifuged at 4000 r / min for 5 min, and then the solvent and wet salt were separated.

[0087] Organic waste salts 2 and 3 were treated according to the method of the control experiment 6 for treating organic waste salt 1.

[0088] Example sample test:

[0089] The TOC removal rates of the organic waste salts 1, 2 and 3 in each example and control experiment were determined, and the results are shown in Tables Figure 2 and Figure 3 Comparing Figure 1 and Figure 2It can be seen that the TOC removal rate of the organic waste salt treated by the low eutectic solvent and method of the present application is all above 80%, while the removal rate of the control experiment is only above 70%, and is about 10% lower than each embodiment. It shows that the conditions in the method of the present application can directly affect the removal effect, and whether the ultrasound is used or not, and the frequency, power and other conditions of the ultrasound have great influence on the TOC removal rate. It can also be seen from the figure that the treatment effect of the method of the present application on the three kinds of waste salts is relatively average, but the TOC removal rate of the eutectic solvent prepared from choline chloride and urea in embodiment 1 is obviously better than that of the eutectic solvent prepared from quaternary ammonium polyamine and monoethanolamine in embodiment 6, which shows that the composition of the eutectic solvent of the present application has obvious influence on the treatment effect of the organic waste salt.

[0090] The XRF characterization results of the organic waste salts 1-3 before and after treatment in embodiment 1 are shown in Tables 2-4:

[0091] Table 2: Organic waste salt 1:

[0092] element Before treatment After processing O 19.7668％ 14.1792％ Cl 39.8518％ 45.1822％ Na 30.8884％ 36.8571％ Si 0.3573％ 0.2314％ K 1.3951％ 0.9121％ C 1.8762％ 1.6378％ Ca 0.2532％ 0.1861％ Mg 0.4164％ 0.3956％ S 5.1948％ 0.4185％

[0093] Table 3: Organic waste salt 2:

[0094] element Before treatment After processing O 25.2236％ 15.4359％ Cl 33.4377％ 44.8739％ Na 29.3267％ 36.3798％ N 0.7375％ 0.4256％ Fe 1.3638％ 1.0135％ C 5.3652％ 1.2547％ Ca 0.1638％ 0.0942％ Al 0.1869％ 0.1533％ S 4.1948％ 0.3691％

[0095] Table 4: Organic waste salt 3:

[0096] element Before treatment After processing O 32.2488％ 11.9399％ Cl 28.2271％ 46.7438％ Na 25.2695％ 35.1257％ Br 4.3473％ 0.4263％ K 1.2436％ 0.9124％ C 1.5198％ 2.6378％ N 0.8351％ 0.9861％ Si 0.1542％ 0.3841％ P 6.1546％ 0.8439％

[0097] It can be seen from the above Tables 2-4 that the S and P elements in the organic waste salt decrease obviously after treatment, which shows that the method of the present application has obvious removal effect on such acid radical ions. At the same time, the contents of O, Br, K, C, Ca and other elements in the treated organic waste salt also decrease obviously, and the main remaining substance is NaCl, which shows that the method of the present application can not only remove S and P-based acid radicals, but also has obvious removal effect on other halogens and metal elements, so that the obtained NaCl salt is more pure, which not only realizes the removal of organic matter, but also establishes a good foundation for the resource utilization of salt.

[0098] For those skilled in the art, other various corresponding changes and modifications can be made according to the above described technical solutions and concepts, and all these changes and modifications should belong to the protection scope of the claims of the present application.

Claims

1. A method for extracting organic waste salt using a deep eutectic solvent, characterized in that: A hydrogen bond donor and a hydrogen bond acceptor are prepared by ultrasonic-assisted heating to obtain a low eutectic solvent; the low eutectic solvent and organic waste salt are mixed by ultrasonic-assisted mixing to obtain a mixed liquid; the mixed liquid is subjected to solid-liquid separation to obtain wet salt and solvent; the wet salt is fully washed, and the washing liquid and salt are collected.

2. The method for extracting organic waste salt using a deep eutectic solvent according to claim 1, wherein: The hydrogen bond acceptor is a quaternary ammonium salt; the hydrogen bond donor is an organic nitrogen compound or a polyol.

3. The method for extracting organic waste salt using a deep eutectic solvent according to claim 1, wherein: The hydrogen bond acceptor includes one or more of choline chloride, tetrabutylammonium chloride or quaternized polyamine.

4. The method for extracting organic waste salt using a deep eutectic solvent according to claim 2, wherein: The organic nitrogen compound includes one or more of urea, monoethanolamine or diethanolammonium; the polyol includes one or more of glycerol, ethylene glycol or propylene glycol.

5. The method for extracting organic waste salt using a deep eutectic solvent according to claim 1, wherein: The molar ratio of the hydrogen bond acceptor to the hydrogen bond donor is 1:1-5; the mass ratio of the organic waste salt to the low eutectic solvent is 1:1-5.

6. The method for extracting organic waste salt using a deep eutectic solvent according to claim 1, wherein: The ultrasonic power of the ultrasound is 100-200W; the ultrasonic frequency is 20-30kHz; the ultrasonic time is 10-20min; the preparation temperature is 50-80°C; the preparation time is 20-40min; the mixing temperature is 25-60°C; and the mixing time is 20-35min.

7. The method for extracting organic waste salt using a deep eutectic solvent according to claim 1, wherein: The wet salt is fully dispersed in ethanol at a mass ratio of 1:1 to 1.5, and the salt and washing liquid are separated and collected.

8. The method for extracting organic waste salt using a deep eutectic solvent according to claim 1, wherein: The solvent and washing liquid are purified to recover the deep eutectic solvent.

9. The method for extracting organic waste salt using a deep eutectic solvent according to claim 8, wherein: The purification comprises filtering the solvent and the washing liquid, and then dehydrating the mixture; and distilling the mixture under reduced pressure at 75-85° C. to recover the low eutectic solvent.

10. Use of the method for extracting organic waste salts using a deep eutectic solvent according to any one of claims 1 to 9 in wastewater treatment, characterized in that: The organic matter in the organic waste salt is more than one kind.

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