Liquid-liquid condensed phase system, preparation method thereof and method for removing organic pollutants in wastewater

Abstract

The invention relates to a liquid-liquid condensed phase system, a preparation method thereof and a method for removing organic pollutants in wastewater. When the liquid-liquid condensed phase system is applied to treatment of wastewater containing organic pollutants, the organic pollutants in the wastewater can be enriched on an upper condensed phase, so that the removal after-treatment is facilitated, and the liquid-liquid condensed phase system has the characteristics of small dosage, no volatilization, no toxicity and no secondary pollution to the environment.

Description

TECHNICAL FIELD

[0001] The present disclosure relates to the technical field of water treatment, in particular, to a liquid-liquid coacervate phase system, a preparation method thereof and a method for removing organic pollutants from wastewater. BACKGROUND

[0002] As an important class of chemical raw materials, phenolic compounds are one of the industrial wastewater that is harmful and widespread at present. The dyes and phenolic compounds in wastewater are complex in composition, difficult to degrade and highly toxic, making it difficult to handle. Therefore, it is of great significance to develop effective technologies for treating organic pollutant wastewater.

[0003] Liquid-liquid extraction treatment is a common organic pollutant-containing wastewater recovery treatment process in industrial applications. Common extractants include ethyl acetate, tributyl phosphate, benzene, etc. The principle is to separate organic pollutants by taking advantage of their different solubilities in water and organic phases. However, traditional extractants have strong volatility, are prone to produce volatile organic compounds, are highly toxic, require large amounts of extractants, and have low distribution coefficients.

[0004] In recent years, liquid-liquid coacervate phase separation has attracted widespread attention in the enrichment and concentration of organic pollutants. This is because the coacervate phase is composed of a large number of sponge-like porous microdomains, which can effectively adsorb and enrich organic pollutants to achieve the removal of organic pollutants. Liquid-liquid coacervate phase separation has the characteristics of low dosage, low toxicity and high enrichment efficiency, and is a technology with good application prospects for the treatment of organic pollutant wastewater.

[0005] Liquid-liquid coacervate phase systems are mainly formed by one or more colloidal substances through non-covalent interactions, which spontaneously separate into two immiscible liquid phases in an aqueous solution, one of which is a dilute phase and the other is a concentrated phase. For example, sodium dodecyl sulfate, poly(diallyldimethylammonium chloride) and polyethylene glycol octylphenyl ether) can form a coacervate phase with the concentrated phase at the bottom (Environ. Sci. Technol. 2001, 35, 2608-2611). Trimer imine cationic surfactant and polyacrylamide can form a coacervate phase at the bottom at pH 12.5, but cannot form a coacervate phase under neutral or acidic conditions (Langmuir 2021, 37, 5993-6001). However, most of the coacervate phases currently formed require a large amount of charged polymers to assist, and the formation of coacervate phases has a very narrow condition interval. In addition, most of the liquid-liquid coacervate phase systems currently formed will form an enrichment phase at the bottom of the solution, which is not conducive to the post-processing operation of organic pollutant removal in the process, and there is a lack of methods to selectively control the enrichment of coacervate phase in the upper layer of the solution. It is urgent to develop a simple and controllable method for preparing coacervate phase to quickly promote the industrial application of coacervate phase separation in the treatment of organic pollutant wastewater. SUMMARY

[0006] The present disclosure aims to provide a liquid-liquid condensed phase system, a preparation method thereof and a method for removing organic pollutants from wastewater. When the liquid-liquid condensed phase system is applied to the treatment of wastewater containing organic pollutants, the organic pollutants in the wastewater can be enriched in the upper condensed phase, which is convenient for removal and post-treatment, and has the characteristics of small dosage, non-volatility, non-toxicity and no secondary pollution to the environment.

[0007] To achieve the above-mentioned purpose, the first aspect of the present disclosure provides a liquid-liquid condensed phase system, which is composed of an anionic surfactant, an inorganic salt, an organic base and water. Based on the total weight of the liquid-liquid condensed phase system, the content of the anionic surfactant is 1-15 wt%, the content of the inorganic salt is 4-25 wt%, the content of the organic base is 0.5-4 wt%, and the balance is water; the anionic surfactant is selected from one or more of alkyl sulfonate with carbon number of 8-16, alkyl sulfate with carbon number of 8-16, aryl sulfonate with carbon number of 8-22 and α-alkenyl sulfonate with carbon number of 14-18; the inorganic salt is selected from one or more of sulfate, halide, carbonate, bicarbonate, phosphate and silicate of alkali metal or alkaline earth metal; the organic base is selected from amine organic base and / or pyridine organic base.

[0008] Optionally, based on the total weight of the liquid-liquid condensed phase system, the content of the anionic surfactant is 1-10 wt%, the content of the inorganic salt is 15-25 wt%, the content of the organic base is 0.5-2 wt%, and the balance is water; preferably, the weight ratio of the anionic surfactant to the inorganic salt is 1:(1-25), preferably 1:(1-20); the weight ratio of the anionic surfactant to the organic base is 1:(0.03-2), preferably 1:(0.1-1).

[0009] Optionally, the alkyl sulfonate with carbon number of 8-16 is selected from one or more of petroleum sodium sulfonate, decyl sodium sulfonate, dodecyl sodium sulfonate and tetradecyl sodium sulfonate; the alkyl sulfate with carbon number of 8-16 is selected from one or more of octyl sodium sulfate, decyl sodium sulfate, dodecyl sodium sulfate and tetradecyl sodium sulfate; the aryl sulfonate with carbon number of 8-22 is selected from one or more of heavy alkyl benzene sodium sulfonate, dodecyl benzene sodium sulfonate, tetradecyl benzene sodium sulfonate, butyl naphthalene sodium sulfonate and dodecyl naphthalene sodium sulfonate; the α-alkenyl sulfonate with carbon number of 14-18 is selected from tetradecyl α-alkenyl sodium sulfonate and / or hexadecyl α-alkenyl sodium sulfonate; preferably, the anionic surfactant is selected from alkyl sulfonate with carbon number of 8-16 and / or aryl sulfonate with carbon number of 8-16.

[0010] Optionally, the inorganic salt is selected from halide salts of alkali metals or alkaline earth metals, preferably from chloride salts of alkali metals or alkaline earth metals.

[0011] Optionally, the organic base is selected from amine organic bases, the amine organic bases are selected from one or more of polyether amines, alkoxy polyoxyethylene amines and bis-amines; the polyether amines are selected from one or more of polyether amine T403, polyether amine D230 and polyether amine D400; the alkoxy polyoxyethylene amines are selected from methoxy polyoxyethylene amines, the average molecular weight of the methoxy polyoxyethylene amines is 750-2000; the bis-amines are selected from one or more of ethylenediamine, 2,2'-oxobis-ethylamine and polyoxyethylene bis-amine; preferably, the amine organic bases are selected from primary amine organic bases.

[0012] Optionally, the anionic surfactant is selected from one or more of dodecyl sulfonate, sodium petroleum sulfonate and sodium heavy alkyl benzene sulfonate, the inorganic salt is selected from one or more of NaCl, KCl, NaI and KBr, and the organic base is selected from polyether amine T403 and / or polyether amine D400.

[0013] The second aspect of the present disclosure provides a method for preparing the liquid-liquid coacervate phase system of the first aspect of the present disclosure, the method comprising: mixing and stirring an anionic surfactant, an inorganic salt and an organic base with water, the stirring speed is 200-500 rpm.

[0014] The third aspect of the present disclosure provides a method for removing organic pollutants from wastewater, the method comprising: contacting the liquid-liquid coacervate phase system of the first aspect of the present disclosure with wastewater containing organic pollutants.

[0015] Optionally, the weight ratio of the liquid-liquid coacervate phase system to the wastewater is (1-10):1, and the contacting conditions include: temperature is 25-70℃, stirring speed is 100-500 rpm, and stirring time is 0.1-2h.

[0016] Optionally, the organic pollutants include one or more of phenol, Nile blue A and methylene blue, and the content of the organic pollutants in the wastewater is 10-180 mg / L, and the content of phenol is 10-120 mg / L.

[0017] Through the above technical solution, this disclosure provides a liquid-liquid condensed phase system, its preparation method, and a method for removing organic pollutants from wastewater. The liquid-liquid condensed phase system is composed of anionic surfactants, inorganic salts, organic bases, and water in a specific ratio. The active amine sites of the organic base can non-covalently bind to the head groups of the anionic surfactant, altering the molecular curvature of the anionic surfactant. The ionic effect of the inorganic salt can induce dehydration between the anionic surfactant and the organic base. These three components spontaneously undergo non-covalent co-assembly in an aqueous solution, forming a thermodynamically stable, layered, and controllable liquid-liquid condensed phase system. The upper layer of this system is a condensed phase existing in the form of a microemulsion, and the lower layer is a diluted phase existing in the form of an aqueous solution. The microemulsion droplets of the condensed phase possess a unique network-like porous structure, which facilitates the formation of numerous hydrophilic and hydrophobic microregions. These hydrophilic and hydrophobic microregions can enrich organic pollutants of various structures, even those with significant differences in molecular structure. This disclosed liquid-liquid condensed phase system contains no volatile or toxic components, will not cause secondary pollution to the environment, has low equipment requirements, and is widely applicable. When used to remove organic pollutants from wastewater, it can enrich the organic pollutants in the upper condensed phase, facilitating post-treatment of the removed organic pollutants. Compared with liquid-liquid extraction, this disclosed liquid-liquid condensed phase system requires a smaller dosage, enabling the separation of the maximum amount of organic pollutants with minimal dosage, and can achieve efficient removal of organic pollutants with various structures.

[0018] Other features and advantages of this disclosure will be described in detail in the following detailed description section. Attached Figure Description

[0019] The accompanying drawings are provided to further illustrate the present disclosure and form part of the specification. They are used together with the following detailed description to explain the present disclosure, but do not constitute a limitation thereof. In the drawings:

[0020] Figure 1 This is a layered photograph of the liquid-liquid condensed phase system prepared in Example 1 of this disclosure;

[0021] Figure 2 This is an optical microscopic image of the upper droplet of the liquid-liquid condensed phase system prepared in Example 1 of this disclosure;

[0022] Figure 3 This is an in-situ cryo-scanning electron microscope image of the upper layer of droplets in the liquid-liquid condensed phase system prepared in Example 1 of this disclosure;

[0023] Figure 4 This is an optical photograph of the liquid-liquid condensed phase system used in Embodiment 1 of this disclosure to treat Nile Blue A dye-contaminated wastewater. Detailed Implementation

[0024] The specific embodiments of this disclosure will be described in detail below with reference to the accompanying drawings. It should be understood that the specific embodiments described herein are for illustration and explanation only and are not intended to limit this disclosure.

[0025] The first aspect of this disclosure provides a liquid-liquid condensed phase system, which is composed of anionic surfactant, inorganic salt, organic base and water. Based on the total weight of the liquid-liquid condensed phase system, the content of the anionic surfactant is 1-15% by weight, the content of the inorganic salt is 4-25% by weight, the content of the organic base is 0.5-4% by weight, and the balance is water. The anionic surfactant is selected from one or more of alkyl sulfonates with 8-16 carbon atoms, alkyl sulfates with 8-16 carbon atoms, aryl sulfonates with 8-22 carbon atoms, and α-alkenyl sulfonates with 14-18 carbon atoms. The inorganic salt is selected from one or more of sulfates, halide salts, carbonates, bicarbonates, phosphates and silicates of alkali metals or alkaline earth metals. The organic base is selected from amine organic bases and / or pyridine organic bases.

[0026] The liquid-liquid condensed phase system disclosed herein comprises anionic surfactants, inorganic salts, organic bases, and water in a specific ratio. The active amine sites of the organic base can non-covalently bind to the head groups of the anionic surfactants, altering the molecular curvature of the anionic surfactants. The ionic effect of the inorganic salts induces dehydration between the anionic surfactants and the organic bases. These three components spontaneously undergo non-covalent co-assembly in the aqueous solution, forming a thermodynamically stable, layered, and controllable liquid-liquid condensed phase system. The upper layer of this system is a condensed phase existing in the form of a microemulsion, while the lower layer is a diluted phase existing in the form of an aqueous solution. The microemulsion droplets within the condensed phase possess a unique network-like porous structure, which facilitates the formation of numerous hydrophilic and hydrophobic microregions. These hydrophilic and hydrophobic microregions can enrich organic pollutants with various structures, even those with significant differences in molecular structure.

[0027] In one embodiment of this disclosure, based on the total weight of the liquid-liquid condensed phase system, the content of the anionic surfactant is 1-10% by weight, the content of the inorganic salt is 15-25% by weight, the content of the organic base is 0.5-2% by weight, and the balance is water; preferably, the weight ratio of the anionic surfactant to the inorganic salt is 1:(1-25), more preferably 1:(1-20); the weight ratio of the anionic surfactant to the organic base is 1:(0.03-2), more preferably 1:(0.1-1). In the above embodiment, by selecting the preferred content ratio, it is beneficial to further improve the thermodynamic stability of the liquid-liquid condensed phase system.

[0028] In one embodiment of this disclosure, the alkyl sulfonate having 8 to 16 carbon atoms is selected from one or more of sodium petroleum sulfonate, sodium decyl sulfonate, sodium dodecyl sulfonate, and sodium tetradecyl sulfonate; the alkyl sulfate having 8 to 16 carbon atoms is selected from one or more of sodium octyl sulfate, sodium decyl sulfate, sodium dodecyl sulfate, and sodium tetradecyl sulfate; the aryl sulfonate having 8 to 22 carbon atoms is selected from one or more of sodium heavy alkylbenzene sulfonate (CAS No. 68411-30-3), sodium dodecylbenzene sulfonate, sodium tetradecylbenzene sulfonate, sodium butylnaphthalene sulfonate, and sodium dodecylnaphthalene sulfonate; and the α-alkenyl sulfonate having 14 to 18 carbon atoms is selected from sodium tetradecyl α-alkenyl sulfonate (molecular formula R1-CH=CH-(CH2)). n -SO3Na, R1 is tetradecyl, CAS number 68439-57-6) and / or sodium hexadecyl α-enyl sulfonate (molecular formula R2-CH=CH-(CH2)). n -SO3Na, R2 is hexadecyl (CAS number 68439-57-6); preferably, the anionic surfactant is selected from alkyl sulfonates with 8 to 16 carbon atoms and / or aryl sulfonates with 8 to 16 carbon atoms. In the above embodiments, by selecting the preferred anionic surfactant, it is beneficial to further improve the formation efficiency of the liquid-liquid condensed phase system.

[0029] In this disclosure, alkyl, aryl, or alkenyl groups may or may not have substituents, and the number of carbon atoms refers to the total number of carbon atoms contained in the molecule. For example, an aryl sulfonate with 12 carbon atoms means that the total number of carbon atoms of the aryl group and the substituents on the aryl group is 12.

[0030] In one embodiment of this disclosure, the inorganic salt is selected from alkali metal or alkaline earth metal halide salts, preferably from alkali metal or alkaline earth metal chloride salts. In the above embodiment, by selecting a preferred inorganic salt, it is beneficial to further accelerate the phase separation of the liquid-liquid condensed phase system and promote the enrichment of the condensed phase in the upper layer of the solution.

[0031] In one embodiment of this disclosure, the organic base is selected from amine organic bases, and the amine organic base is selected from one or more of polyetheramines, alkoxy polyoxyethylene amines, and diamines; the polyetheramine is selected from one or more of polyetheramine T403 (CAS No. 39423-51-3, average molecular weight 440), polyetheramine D230 (CAS No. 9046-10-0, average molecular weight 230), and polyetheramine D400 (CAS No. 9046-10-0, average molecular weight 400); the alkoxy polyoxyethylene amine is selected from methoxy polyoxyethylene amine (CAS No. 80506-64-5), and the average molecular weight of the methoxy polyoxyethylene amine is 750-2000; the diamine is selected from one or more of ethylenediamine, 2,2'-oxodiethylamine (CAS No. 2752-17-2), and polyoxyethylene diamine (CAS No. 24991-53-5). In a preferred embodiment, the amine organic base is selected from primary amine organic bases. In the above embodiments, the selection of preferred primary amine organic bases is beneficial for enhancing the intermolecular interaction with anionic surfactants.

[0032] In one embodiment of this disclosure, the anionic surfactant is selected from one or more of dodecyl sulfonate, sodium petroleum sulfonate and sodium heavy alkylbenzene sulfonate, the inorganic salt is selected from one or more of NaCl, KCl, NaI and KBr, and the organic base is selected from polyetheramine T403 and / or polyetheramine D400.

[0033] The second aspect of this disclosure provides a method for preparing the liquid-liquid condensed phase system described in the first aspect of this disclosure, the method comprising: mixing an anionic surfactant, an inorganic salt, an organic base and water and stirring, wherein the stirring speed is 200-500 rpm.

[0034] The third aspect of this disclosure provides a method for removing organic pollutants from wastewater, the method comprising: contacting the liquid-liquid condensate system described in the first aspect of this disclosure with wastewater containing organic pollutants.

[0035] The liquid-liquid condensed phase system disclosed herein contains no volatile toxic components, will not cause secondary pollution to the environment, has low equipment requirements, and has a wide range of applications. When used to remove organic pollutants from wastewater, it can enrich the organic pollutants in the upper condensed phase, facilitating the post-treatment of organic pollutants. Compared with liquid-liquid extraction, the liquid-liquid condensed phase system of this disclosure requires less dosage, which can separate the most organic pollutants with the least amount of dosage. It is applicable to organic pollutants of various structures and can achieve efficient removal of organic pollutants of various structures.

[0036] In one embodiment of this disclosure, the weight ratio of the liquid-liquid condensed phase system to the wastewater is (1-10):1, and the contact conditions include: a temperature of 25-70°C, a stirring speed of 100-500 rpm, and a stirring time of 0.1-2 h.

[0037] In one embodiment of this disclosure, the organic pollutant includes one or more of phenol, Nile Blue A, and methylene blue, and the content of the organic pollutant in the wastewater is 10-180 mg / L, and the content of phenol is 10-120 mg / L.

[0038] The present disclosure is further illustrated by the following examples, but the present disclosure is not limited thereto. Unless otherwise specified, all raw materials used in the examples and comparative examples of the present disclosure are commercially available and are pure reagents.

[0039] Example 1

[0040] 1 g of sodium dodecylbenzenesulfonate (anionic surfactant, CAS No. 25155-30-0), 20 g of sodium chloride (inorganic salt), 0.8 g of polyetheramine T403 (organic base, CAS No. 39423-51-3, average molecular weight 440) was mixed with 78.2 g of water until homogeneous. The mixture was stirred at 400 rpm at room temperature to obtain a liquid-liquid condensed phase system. The specific contents of each component in the liquid-liquid condensed phase system are shown in Table 1.

[0041] When this liquid-liquid condensed phase system is placed in a test tube for observation, it spontaneously separates into two immiscible phases, such as... Figure 1 As shown. Figure 1 It can be seen that the upper layer is a condensed phase existing in the form of droplets, and the lower layer is a transparent diluted phase existing in the form of aqueous solution, indicating that the condensed phase of the liquid-liquid condensed phase system disclosed herein is more likely to form in the upper layer.

[0042] The upper layer droplet of this liquid-liquid condensed phase system was placed on a glass slide and observed using an optical microscope (40x objective lens). The optical micrograph is shown below. Figure 2 As shown, a large number of micron-sized droplets can be seen in the field of view. As time goes on, the small droplets will aggregate and form larger droplets, indicating that the upper layer is a condensed phase in the form of a microemulsion.

[0043] In-situ microscopic imaging of the upper droplet was performed using cryo-scanning electron microscopy. The in-situ cryo-scanning electron microscopy image is shown below. Figure 3 As shown, a special network-like sponge-like microstructure is formed inside the droplet, with a large number of dense porous structures containing numerous hydrophobic microregions.

[0044] Example 2

[0045] 10g of sodium alkylbenzene sulfonate (anionic surfactant, CAS No. 68411-30-3), 20g of sodium chloride (inorganic salt), 4g of polyetheramine D400 (organic base, CAS No. 9046-10-0, average molecular weight 400) were mixed thoroughly with 66g of water and stirred at 400 rpm at room temperature to obtain a liquid-liquid condensed phase system. The specific contents of each component in the liquid-liquid condensed phase system are shown in Table 1.

[0046] The optical micrographs and in-situ cryo-scanning electron microscope images of this liquid-liquid condensed phase system are basically the same as those in Example 1. They also show that the upper layer is a condensed phase in the form of a microemulsion. The condensed phase droplets form a special network-like sponge-like microstructure and have a large number of dense porous structures with a large number of hydrophobic microregions.

[0047] Example 3

[0048] 10g of sodium petroleum sulfonate (anionic surfactant, chemical formula R-SO3Na, where R is an alkyl group with 14-22 carbon atoms), 20g of sodium chloride (inorganic salt), 1g of polyetheramine T403 (organic base) and 69g of water were mixed evenly and stirred at 400 rpm at room temperature to obtain a liquid-liquid condensed phase system. The specific contents of each component in the liquid-liquid condensed phase system are shown in Table 1.

[0049] The optical micrographs and in-situ cryo-scanning electron microscope images of this liquid-liquid condensed phase system are basically the same as those in Example 1. They also show that the upper layer is a condensed phase in the form of a microemulsion. The condensed phase droplets form a special network-like sponge-like microstructure and have a large number of dense porous structures with a large number of hydrophobic microregions.

[0050] Example 4

[0051] Similar to Example 1, except that the content of sodium chloride (inorganic salt) is 4g, so that the weight ratio of anionic surfactant to inorganic salt in the liquid-liquid condensed phase system is 1:4.

[0052] The optical micrographs and in-situ cryo-scanning electron microscope images of this liquid-liquid condensed phase system are basically the same as those in Example 1. They also show that the upper layer is a condensed phase in the form of a microemulsion. The condensed phase droplets form a special network-like sponge-like microstructure and have a large number of dense porous structures with a large number of hydrophobic microregions.

[0053] Example 5

[0054] Same as Example 1, except that the content of polyetheramine T403 (organic base) is 3g, so that the weight ratio of anionic surfactant to organic base in the liquid-liquid condensed phase system is 1:3.

[0055] The optical micrographs and in-situ cryo-scanning electron microscope images of this liquid-liquid condensed phase system are basically the same as those in Example 1. They also show that the upper layer is a condensed phase in the form of a microemulsion. The condensed phase droplets form a special network-like sponge-like microstructure and have a large number of dense porous structures with a large number of hydrophobic microregions.

[0056] Comparative Example 1

[0057] 1g sodium dodecylbenzenesulfonate (anionic surfactant), 20g sodium chloride (inorganic salt), 0.8g sodium carbonate (inorganic base) and 78.2g water were mixed evenly and stirred at 400 rpm at room temperature to obtain a mixed system. The specific contents of each component in the mixed system are shown in Table 1.

[0058] When the mixture was placed in a test tube for observation, the solution did not separate into layers, indicating that the mixture did not form the liquid-liquid condensed phase system disclosed herein.

[0059] Comparative Example 2

[0060] 1g sodium dodecylbenzenesulfonate (anionic surfactant), 0.8g polyetheramine D400 (organic base) and 98.2g water were mixed evenly and stirred at 400 rpm at room temperature to obtain a mixed system. The specific contents of each component in the mixed system are shown in Table 1.

[0061] When the mixture was placed in a test tube for observation, the solution did not separate into layers, indicating that the mixture did not form the liquid-liquid condensed phase system disclosed herein.

[0062] Comparative Example 3

[0063] 1g sodium dodecylbenzenesulfonate (anionic surfactant), 20g sodium chloride (inorganic salt), 8g polyetheramine T403 (organic base) and 71g water were mixed evenly and stirred at 400 rpm at room temperature to obtain a mixed system. The specific contents of each component in the mixed system are shown in Table 1.

[0064] When the mixture was placed in a test tube for observation, the solution did not separate into layers, indicating that the mixture did not form the liquid-liquid condensed phase system disclosed herein.

[0065] Comparative Example 4

[0066] 1g of sodium dodecanoate (carboxylate-type anionic surfactant, CAS number 629-25-4), 20g of sodium chloride (inorganic salt), 0.8g of polyetheramine D400 (organic base) and 78.2g of water were mixed evenly and stirred at 400 rpm at room temperature to obtain a mixed system. The specific contents of each component in the mixed system are shown in Table 1.

[0067] When the mixture was placed in a test tube for observation, the solution did not separate into layers, indicating that the mixture did not form the liquid-liquid condensed phase system disclosed herein.

[0068] Table 1

[0069]

[0070]

[0071] Test case

[0072] The liquid-liquid condensed phase systems prepared in Examples 1-5 and the mixed systems prepared in Comparative Examples 1-4 were used as test samples. 10g of each test sample was mixed with 10g of Nile Blue A dye-contaminated wastewater and 10g of phenol-contaminated wastewater (both containing 100mg / L of organic pollutants). The weight ratio of test sample to wastewater was 1:1. The mixture was stirred at 25°C and 350 rpm for 10 minutes and then allowed to stand. The mixed solution spontaneously separated into two immiscible phases. The results of treating Nile Blue A dye-contaminated wastewater using the liquid-liquid condensed phase system in Example 1 are as follows: Figure 4 As shown, the upper layer is a condensed phase enriched with Nile Blue A dye, and the lower layer is a colorless and transparent diluted phase that exists mainly in the form of an aqueous solution.

[0073] The upper condensed phase was tested using ultraviolet absorption spectroscopy, and the concentration C of pollutants in the upper condensed phase was calculated based on the linear relationship between absorbance and Nile Blue A and phenol concentrations. Then, the enrichment efficiency of the sample for Nile Blue A and phenol was calculated using the formula (C0-C) / C0*100%, where the initial concentration of pollutants was denoted as C0. The calculation results of the enrichment efficiency are shown in Table 2.

[0074] Table 2

[0075]

[0076]

[0077] As can be seen from the results in Table 2 above, the liquid-liquid condensed phase systems provided in Examples 1-5 of this disclosure have the characteristic of controllable stratification. The upper layer is a condensed phase formed by microemulsions. The droplets of this condensed phase have a unique network-like sponge-like microstructure. The dense porous structure inside contains a large number of hydrophilic and hydrophobic microregions. When used to remove organic pollutants from wastewater, the hydrophilic and hydrophobic microregions can enrich the organic pollutants in the wastewater in the upper condensed phase, which facilitates the post-treatment of organic pollutants. However, Comparative Examples 1-4 did not adopt the technical solution of this disclosure. Comparative Example 1 did not use an organic base, Comparative Example 2 did not use an inorganic salt, Comparative Example 3 did not use the component content of this disclosure, and Comparative Example 4 did not use the sulfonate-type anionic surfactant of this disclosure, but instead used a carboxylate-type anionic surfactant. The mixed systems prepared by these examples could not form a liquid-liquid condensed phase system and could not effectively enrich the organic pollutants in the wastewater.

[0078] The preferred embodiments of this disclosure have been described in detail above with reference to the accompanying drawings. However, this disclosure is not limited to the specific details of the above embodiments. Within the scope of the technical concept of this disclosure, various simple modifications can be made to the technical solutions of this disclosure, and these simple modifications all fall within the protection scope of this disclosure.

[0079] It should also be noted that the various specific technical features described in the above specific embodiments can be combined in any suitable manner without contradiction. In order to avoid unnecessary repetition, this disclosure will not describe the various possible combinations separately.

[0080] Furthermore, various different embodiments of this disclosure can be combined in any way, as long as they do not violate the spirit of this disclosure, they should also be regarded as the content disclosed in this disclosure.

Claims

1. A liquid-liquid condensed phase system, characterized in that, The liquid-liquid condensed phase system is composed of anionic surfactants, inorganic salts, organic bases and water. Based on the total weight of the liquid-liquid condensed phase system, the content of the anionic surfactant is 1-15% by weight, the content of the inorganic salt is 4-25% by weight, the content of the organic base is 0.5-4% by weight, and the balance is water. The anionic surfactant is selected from one or more of the following: alkyl sulfonates with 8 to 16 carbon atoms, alkyl sulfates with 8 to 16 carbon atoms, aryl sulfonates with 8 to 22 carbon atoms, and α-olefin sulfonates with 14 to 18 carbon atoms. The inorganic salt is selected from one or more of the following: sulfates, halides, carbonates, bicarbonates, phosphates, and silicates of alkali metals or alkaline earth metals. The organic base is selected from amine organic bases and / or pyridine organic bases.

2. The liquid-liquid condensed phase system according to claim 1, characterized in that, Based on the total weight of the liquid-liquid condensed phase system, the content of the anionic surfactant is 1-10% by weight, the content of the inorganic salt is 15-25% by weight, the content of the organic base is 0.5-2% by weight, and the remainder is water. Preferably, the weight ratio of the anionic surfactant to the inorganic salt is 1:(1-25), more preferably 1:(1-20); the weight ratio of the anionic surfactant to the organic base is 1:(0.03-2), more preferably 1:(0.1-1).

3. The liquid-liquid condensed phase system according to claim 1, characterized in that, The alkyl sulfonate having 8 to 16 carbon atoms is selected from one or more of sodium petroleum sulfonate, sodium decyl sulfonate, sodium dodecyl sulfonate, and sodium tetradecyl sulfonate. The alkyl sulfate having 8 to 16 carbon atoms is selected from one or more of sodium octyl sulfate, sodium decyl sulfate, sodium dodecyl sulfate, and sodium tetradecyl sulfate; The aryl sulfonate having 8 to 22 carbon atoms is selected from one or more of sodium heavy alkylbenzene sulfonate, sodium dodecylbenzene sulfonate, sodium tetradecylbenzene sulfonate, sodium butylnaphthalene sulfonate, and sodium dodecylnaphthalene sulfonate; The α-alkenyl sulfonate having 14 to 18 carbon atoms is selected from sodium tetradecyl α-alkenyl sulfonate and / or sodium hexadecyl α-alkenyl sulfonate. Preferably, the anionic surfactant is selected from alkyl sulfonates having 8 to 16 carbon atoms and / or aryl sulfonates having 8 to 16 carbon atoms.

4. The liquid-liquid condensed phase system according to claim 1, characterized in that, The inorganic salt is selected from alkali metal or alkaline earth metal halide salts, preferably from alkali metal or alkaline earth metal chloride salts.

5. The liquid-liquid condensed phase system according to claim 1, characterized in that, The organic base is selected from amine organic bases, and the amine organic base is selected from one or more of polyetheramines, alkoxy polyoxyethyleneamines, and diamines; The polyetheramine is selected from one or more of polyetheramine T403, polyetheramine D230 and polyetheramine D400; The alkoxy polyoxyethylene amine is selected from methoxy polyoxyethylene amine, and the average molecular weight of the methoxy polyoxyethylene amine is 750-2000. The diamine is selected from one or more of ethylenediamine, 2,2'-oxodiethylamine and polyoxyethylene diamine; Preferably, the amine organic base is selected from primary amine organic bases.

6. The liquid-liquid condensed phase system according to claim 1, characterized in that, The anionic surfactant is selected from one or more of dodecyl sulfonate, sodium petroleum sulfonate and sodium heavy alkylbenzene sulfonate; the inorganic salt is selected from one or more of NaCl, KCl, NaI and KBr; and the organic base is selected from polyetheramine T403 and / or polyetheramine D400.

7. A method for preparing the liquid-liquid condensed phase system according to any one of claims 1 to 6, characterized in that, The method includes: mixing anionic surfactant, inorganic salt, organic base and water and stirring, wherein the stirring speed is 200-500 rpm.

8. A method for removing organic pollutants from wastewater, characterized in that, The method includes contacting the liquid-liquid condensed phase system according to any one of claims 1 to 6 with wastewater containing organic pollutants.

9. The method according to claim 8, characterized in that, The weight ratio of the liquid-liquid condensed phase system to the wastewater is (1-10):

1. The contact conditions include: temperature of 25-70℃, stirring speed of 100-500 rpm, and stirring time of 0.1-2h.

10. The method according to claim 8, characterized in that, The organic pollutants include one or more of phenol, Nile Blue A, and methylene blue, and the content of organic pollutants in the wastewater is 10-180 mg / L, and the content of phenol is 10-120 mg / L.

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