Green multi-functional-group ionic liquid and method for purifying complex wastewater containing heavy metals by using same

Abstract

The invention provides a green polyfunctional ionic liquid and a method for purifying heavy metal-containing complex wastewater by using the same, and belongs to the field of wastewater purification, cations of the ionic liquid are ergothioneine and derivatives thereof, a sulfur-substituted imidazole ring exists in a molecular skeleton, thioaldehyde groups can be converted into sulfydryl groups under specific conditions, and the sulfydryl groups and 1, 2, 3, 3, 3, 3, 3, 3, 3, 3, 3, 3, 3, 3, 3, 3, 3, 3, 3, 3, 3, 3, 3, 3, 3, 3, 3, 3 According to the ionic liquid, lone pair electrons on a nitrogen heteroatom at the position 1, 3 cooperate to form a potential chelating ligand, carboxyl and quaternary ammonium salt in a main chain structure cooperate with each other and can form a five-membered ring structure with target metal ions, meanwhile, carboxyl, quaternary ammonium salt and sulfydryl belong to hydrophilic functional groups of different structures, the hydrophilicity of the ionic liquid under the condition of a wide pH window is guaranteed, and the ionic liquid can be used in the field of metal ions. The dissolving property of the ionic liquid is facilitated. High-flux purification of complex wastewater containing heavy metals is realized through regulation and control of anion and cation systems of the ionic liquid and mutual cooperation of different functional groups in space structures, functional group types and molecular structures of cations.

Description

Technical Field

[0001] The invention relates to the technical field of heavy metal-containing wastewater purification, and in particular to a green multifunctional ionic liquid and a method for purifying complex heavy metal-containing wastewater using the same. Background Art

[0002] At present, sodium sulfide, sodium hydrosulfide and other precipitants are often used to purify industrial wastewater containing heavy metals. During use, sodium hydrosulfide and sodium sulfide are easily hydrolyzed to produce hydrogen sulfide, which poses potential environmental and safety problems. In order to solve the environmental limitations of the above-mentioned purifiers, researchers are committed to the development of new green purifiers, such as a polyion gel adsorption material with an imidazole-long carbon cross-linked molecular structure as the skeleton, which can achieve the regulation of functional group types and greatly expand its application in wastewater treatment and other fields, but it still has certain limitations: first, the adsorption flux is poor and the adsorption efficiency is limited; second, it cannot meet the high-throughput purification of target metal ions in complex solutions containing heavy metals, that is, in the stage of adsorbing heavy metal ions, it is difficult to achieve a one-time purification effect of multiple types of target metals; third, during the derivatization process of polyion gel adsorption materials, it is limited by the synthesis path and cannot introduce multiple types of functional groups, which limits the applicable field.

[0003] Ionic liquids are organic salts that are liquid at room temperature and are composed of organic cations and inorganic or organic anions. As a new type of polar solvent, ionic liquids are also called "green" chemical solvents because they have almost no vapor pressure, are non-flammable, non-volatile, have good chemical and thermal stability, are recyclable, and are environmentally friendly. Due to their excellent properties, ionic liquids are widely used in different aspects of the chemical industry, such as chemical separation processes, electrochemistry, and chemical reactions. They are not only excellent solvents for many reactions, but can also be used as catalysts for reactions. Expanding the use of ionic liquids to treat heavy metal wastewater is in line with the concept of green environmental protection management.

[0004] In view of this, it is necessary to design an improved green multifunctional ionic liquid and a method for purifying complex wastewater containing heavy metals to solve the above problems. Summary of the invention

[0005] In view of the technical problems existing in the background technology, the present application provides a green multifunctional ionic liquid and a method for purifying complex wastewater containing heavy metals, aiming to solve the technical problem that it is difficult to achieve high-throughput purification effect in complex heavy metal wastewater systems.

[0006] In a first aspect, the present application provides a green multifunctional ionic liquid, the general structural formula of the green multifunctional ionic liquid is as follows: ; Wherein, n ≥ 0, X represents the anion of the ionic liquid; The anion of the ionic liquid is F - Br - , Cl - ,I - One or more of .

[0007] In a second aspect, the present application provides a method for purifying complex wastewater containing heavy metals using a green multifunctional ionic liquid, wherein the green multifunctional ionic liquid described in the first aspect is used to purify complex wastewater containing heavy metals, comprising the following steps: S1. Adjust the pH value of complex wastewater containing heavy metals to a predetermined range; S2. Add the green multifunctional ionic liquid to the complex wastewater containing heavy metals, shake in a water bath for a predetermined time, filter and separate the solid phase, detect the concentration of each metal ion in the liquid phase solution, and calculate the purification rate.

[0008] As a further improvement of the present application, the metal ions in the complex wastewater containing heavy metals include Fe 2+ , Fe 3+ , Cu + , Cu 2+ , Hg + , Pb 2+ 、Au + 、Au 3+ 、Ag + One or more of .

[0009] As a further improvement of the present application, the anions in the complex wastewater containing heavy metals include F - Br - , Cl - ,I - , S 2 O 3 2- , CN - , citrate or more.

[0010] As a further improvement of the present application, the pH value of the complex wastewater containing heavy metals is 5~13.

[0011] As a further improvement of the present application, the temperature of the water bath shaking is 25-28° C., and the time is 30-40 min.

[0012] As a further improvement of the present application, the complex wastewater containing heavy metals is one or more of electronic waste treatment waste liquid, circuit board etching liquid, and gold cyanide waste liquid.

[0013] The beneficial effects of this application are: The present application provides a green multifunctional ionic liquid and a method for purifying complex wastewater containing heavy metals. The cation of the green multifunctional ionic liquid is ergothioneine and its derivatives. There is a sulfur-substituted imidazole ring in the molecular skeleton. Under specific conditions, the thioaldehyde group can be converted into a sulfhydryl group. The lone pair of electrons on the nitrogen heteroatoms at positions 1 and 3 in the sulfhydryl group and the aromatic ring cooperate to form a potential chelating ligand. The main chain structure contains carboxyl and quaternary ammonium salt at the same time. The mutual cooperation of carboxyl and quaternary ammonium salt can form a five-membered ring structure with the target metal ion. At the same time, carboxyl, quaternary ammonium salt and sulfhydryl belong to hydrophilic functional groups of different structures, which ensures the hydrophilicity of the green multifunctional ionic liquid under a wide pH window, which is beneficial to the solubility of the ionic liquid.

[0014] By regulating the anion and cation system of green multifunctional ionic liquids, as well as the spatial structure of cations, the types of functional groups and the mutual collaboration between different functional groups in the molecular structure, high-throughput purification of complex wastewater containing heavy metals can be achieved.

[0015] The above description is only an overview of the technical solution of the present application. In order to more clearly understand the technical means of the present application, it can be implemented in accordance with the contents of the specification. In order to make the above and other purposes, features and advantages of the present application more obvious and easy to understand, the specific implementation methods of the present application are listed below. BRIEF DESCRIPTION OF THE DRAWINGS

[0016] In order to more clearly illustrate the technical solution of the present application, the following is a brief introduction to the drawings used in the present application. Obviously, the drawings described below are only some embodiments of the present application, and for ordinary technicians in this field, other drawings can be obtained based on these drawings without creative work.

[0017] Figure 1 The mechanism of action of the green multifunctional ionic liquid provided in this application with the target metal ions and the potential chelating products; Figure 2 The precipitate produced after the heavy metal-containing wastewater is purified in Example 1 of the present application; Figure 3 This is a physical picture of the wastewater after purification in Examples 5-9 of the present application. DETAILED DESCRIPTION

[0018] The following embodiments of the technical solution of the present application are described in detail in conjunction with the accompanying drawings. The following embodiments are only used to more clearly illustrate the technical solution of the present application, and are therefore only used as examples, and cannot be used to limit the scope of protection of the present application.

[0019] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by technicians in the technical field to which this application belongs; the terms used herein are only for the purpose of describing specific embodiments and are not intended to limit this application; the terms "including" and "having" in the specification and claims of this application and the above-mentioned figure descriptions and any variations thereof are intended to cover non-exclusive inclusions.

[0020] In the description of the embodiments of the present application, the technical terms "first", "second", etc. are only used to distinguish different objects, and cannot be understood as indicating or implying relative importance or implicitly indicating the number, specific order or primary and secondary relationship of the indicated technical features. In the description of the embodiments of the present application, the meaning of "multiple" is more than two, unless otherwise clearly and specifically defined.

[0021] Reference to "embodiments" herein means that a particular feature, structure, or characteristic described in conjunction with the embodiments may be included in at least one embodiment of the present application. The appearance of the phrase in various locations in the specification does not necessarily refer to the same embodiment, nor is it an independent or alternative embodiment that is mutually exclusive with other embodiments. It is explicitly and implicitly understood by those skilled in the art that the embodiments described herein may be combined with other embodiments.

[0022] Currently, traditional purifiers involving heavy metals in wastewater, such as sodium sulfide and sodium hydrosulfide precipitants, are easily hydrolyzed to produce harmful gases, and have certain limitations from an environmental perspective; while the new polyion gel adsorbent material has a low adsorption flux, making it difficult to achieve high-throughput purification of complex heavy metal wastewater systems.

[0023] In order to solve the technical problems of environmental limitations and insufficient high-throughput purification effect of traditional purifiers when treating heavy metals in wastewater, the present application provides a green multi-functional ionic liquid and a method for purifying complex wastewater containing heavy metals, wherein the ionic liquid with a specific structure forms a stable complex with the heavy metal ions, thereby achieving the technical effect of high-throughput purification of complex wastewater containing heavy metals.

[0024] In the first aspect, the present invention provides a green multifunctional ionic liquid, the general structure of which is as follows: , where n≥0 and X represents an ionic liquid anion.

[0025] The cation of the green multifunctional ionic liquid provided by the present application is ergothioneine and its derivatives, there is a sulfur-substituted imidazole ring in the molecular skeleton, the thioaldehyde group can be converted into a thiol group under specific conditions, the thiol group cooperates with the lone pair of electrons on the nitrogen heteroatoms at the 1 and 3 positions in the aromatic ring to form a potential chelating ligand, and the main chain structure contains both a carboxyl group and a quaternary ammonium salt. The mutual cooperation of the carboxyl group and the quaternary ammonium salt can form a five-membered ring structure with the target metal ion. At the same time, the carboxyl group, the quaternary ammonium salt and the thiol group belong to hydrophilic functional groups of different structures, which ensures the hydrophilicity of the green multifunctional ionic liquid under a wider pH window condition, which is beneficial to the solubility performance of the ionic liquid.

[0026] Specifically, the anion of the ionic liquid is F - Br - , Cl - ,I - One or more of .

[0027] In the technical solution of the embodiment of the present application, by adjusting the anion type of the green multifunctional ionic liquid, the water miscibility of the ionic liquid can be directionally changed to achieve interface regulation from the inorganic phase to the organic phase. Through the regulation of the anion and cation system of the green multifunctional ionic liquid, as well as the spatial structure of the cation, the type of functional group and the mutual cooperation between different functional groups in the molecular structure, high-throughput purification of complex wastewater containing heavy metals can be achieved.

[0028] In a second aspect, an embodiment of the present application provides a method for purifying complex wastewater containing heavy metals using a green multifunctional ionic liquid, wherein the green multifunctional ionic liquid described in the first aspect is used to purify complex wastewater containing heavy metals, comprising the following steps: S1. Adjust the pH value of complex wastewater containing heavy metals to a predetermined range; S2. Add green multifunctional ionic liquid to complex wastewater containing heavy metals, shake in a water bath for a predetermined time, filter and separate the solid phase, detect the concentration of each metal ion in the liquid solution, and calculate the purification rate.

[0029] Among them, adjusting the pH value helps to optimize the adsorption efficiency of green multifunctional ionic liquids for heavy metal ions. Water bath shaking can enhance the contact between green multifunctional ionic liquids and heavy metal ions and improve the adsorption efficiency. After the shaking is completed, the solid phase containing heavy metal ions (i.e., the complex of ionic liquids and heavy metal ions) is separated from the liquid phase by filtration, and the metal ion concentration of the filtered liquid phase is tested to evaluate the purification effect. The purification rate is calculated based on the change in metal ion concentration to quantify the purification effect of the ionic liquid.

[0030] Specifically, the calculation formula for the purification rate of green multifunctional ionic liquid is: Purification rate (%) = 1- ×100%.

[0031] Furthermore, in some embodiments, the metal ions in the heavy metal-containing complex wastewater include Fe 2+ , Fe 3+ , Cu + , Cu 2+ , Hg + , Pb 2+ 、Au + 、Au 3+ 、Ag + One or more of the following. Anions in complex wastewater containing heavy metals include F - Br - , Cl - ,I - , S 2 O 3 2- , CN - , citrate or more.

[0032] In the technical solution of the embodiment of the present application, the green multifunctional ionic liquid can effectively remove various heavy metal ions in wastewater containing various complex anions, reduce environmental pollution, and protect water resources; at the same time, the method has the advantages of simple operation and high purification efficiency, and has good application prospects. Specifically, Cl - Taking ionic liquid anions as an example, the chelation mechanism of green multifunctional ionic liquids with metal ions and the potential chelation products are as follows: Figure 1 As shown, a, b, c, d, e, and f are potential chelation products of copper, mercury, iron, gold, silver, and lead, respectively; in the potential chelation product of gold, x and y represent the stoichiometric numbers of chloride ions and hydroxide ions, respectively.

[0033] Furthermore, in some embodiments, the pH value of the heavy metal-containing complex wastewater is 5-13.

[0034] In the technical solution of the embodiment of the present application, the appropriate pH value can affect the adsorption performance of the green multifunctional ionic liquid and the existence form of heavy metal ions, thereby affecting the interaction between the ionic liquid and the heavy metal ions. The appropriate pH value helps to improve the ionic liquid's ability to capture heavy metal ions, ensuring that the wastewater purification effect reaches the expected goal.

[0035] Furthermore, in some embodiments, the temperature of the water bath shaking is 25-28° C., and the time is 30-40 min.

[0036] In the technical solution of the embodiment of the present application, at a suitable temperature, the interaction between the green multifunctional ionic liquid and the heavy metal ions can reach a balanced state, thereby optimizing the adsorption efficiency. The appropriate oscillation time can ensure that the ionic liquid has sufficient time to contact and react with the heavy metal ions in the wastewater, thereby improving the purification rate.

[0037] Furthermore, in some embodiments, the complex wastewater containing heavy metals is one or more of electronic waste treatment waste liquid, circuit board etching liquid, and gold cyanide waste liquid.

[0038] In the technical solution of the embodiment of the present application, the green multifunctional ionic liquid has a wide range of applicability and is suitable for a variety of heavy metal-containing wastewaters. The special functional groups contained in the green multifunctional ionic liquid can coordinate and complex with different metal ions, thereby effectively adsorbing and stabilizing heavy metal ions. At the same time, the green multifunctional ionic liquid can adapt to wastewater with very different heavy metal concentrations. When the heavy metal content is low, a small amount of green multifunctional ionic liquid can achieve the treatment effect; when the heavy metal content is high, it is necessary to increase the amount of green multifunctional ionic liquid. In addition, the purification rate can be improved by multiple purifications. In practical applications, the treatment effect and economic cost are balanced according to the specific situation.

[0039] Some specific embodiments are listed below. It should be noted that the embodiments described below are exemplary and are only used to explain the present application, and should not be construed as limiting the present application. If specific techniques or conditions are not specified in the embodiments, the techniques or conditions described in the literature in this area or the product specifications are used. The reagents or instruments used without specifying the manufacturer are all conventional products that can be obtained commercially.

[0040] Example 1 This embodiment provides a green multifunctional ionic liquid, the structural formula of which is as follows: The green multifunctional ionic liquid was used to purify complex wastewater containing heavy metals, wherein the wastewater to be treated contained 0.5 g / L of iron (Fe 2+ ), copper (Cu 2+ ), mercury (Hg + ), lead (Pb 2+ ), silver (Ag + ) (the anion is citrate) and 0.001g / L of gold thiosulfate mixed wastewater solution, specifically comprising the following steps: S1. Adjust the pH value of the wastewater solution to 5 with nitric acid; S2. Weigh 50 g of the green multifunctional ionic liquid and put it into 1 L of wastewater solution. After shaking in a water bath at 25 ° C for 30 min, filter and separate the solid phase. The precipitate produced after purification is as follows: Figure 2 As shown, the liquid phase is collected and the concentrations of iron, copper, mercury, lead, gold and silver ions in the liquid solution are detected by ICP-OES (inductively coupled plasma optical emission spectrometer), thereby calculating the purification rate of the ionic liquid, wherein the detection error of ICP-OES is ±2%.

[0041] Example 2 Example 2 provides a method for purifying complex wastewater containing heavy metals with a green multifunctional ionic liquid. Compared with Example 1, the only difference is that the temperature of the water bath oscillation is 28°C and the time is 40 minutes. Other parameters and conditions are basically the same as those in Example 1 and will not be repeated here.

[0042] Examples 3-10 and Comparative Example 1 Examples 3-10 and Comparative Example 1 respectively provide a method for purifying complex wastewater containing heavy metals using a green multifunctional ionic liquid. Compared with Example 1, the only difference is that nitric acid or sodium hydroxide is used to adjust the pH value of the wastewater solution, as shown in Table 1. Other parameters and conditions are basically the same as those in Example 1 and will not be repeated here.

[0043] As can be seen from Table 1, the green multifunctional ionic liquid provided in Example 1 has good purification ability for wastewater containing iron, copper, mercury, lead, gold and silver ions. In the pH range of 5 to 13, the purification ability is higher than 90%. The reason is that the special molecular structure of the green multifunctional ionic liquid can chelate with a variety of target metal ions, and the hydrolysis performance of the chelated product deteriorates, precipitates are generated, and they are separated from the solution system. Figure 3 The actual picture of the purified wastewater in Examples 5-9 of this application shows that the bottom of the container is the chelated product and the upper layer is relatively clear purified water. When pH < 5, the C=S bond on the imidazole ring is difficult to isomerize to the imidazole thiol group, the activation site S- is difficult to be activated, and the subsequent chelation reaction is hindered. When pH > 13, metal ions such as iron and copper spontaneously precipitate in the above solution, making it difficult to prepare a specific concentration of iron, copper, mercury, lead, and silver ion solutions.

[0044] Examples 11-14 and Comparative Examples 2-3 Examples 11-14 and Comparative Examples 2-3 respectively provide a method for purifying complex wastewater containing heavy metals with a green multifunctional ionic liquid. Compared with Example 1, the only difference is that the pH value of the wastewater solution is adjusted to 9, and different masses of green multifunctional ionic liquids are added, as shown in Table 2. Other parameters and conditions are basically the same as those in Example 1 and will not be repeated here.

[0045] As can be seen from Table 2, the green multifunctional ionic liquid provided in Example 1 requires a specific range of addition amounts for its purification ability for wastewater containing iron, copper, mercury, lead, gold and silver ions. Considering the economic cost, the optimal reagent mass range is between 15 and 90 g, and the purification rate of each metal is ≥80%. As the addition amount continues to increase, the purification rate of each metal no longer increases because the chelates of each metal are slightly soluble in water.

[0046] Comparative Examples 4-6 Comparative Examples 4-6 respectively provide a method for purifying complex wastewater containing heavy metals using a green multifunctional ionic liquid, using the green multifunctional ionic liquid provided in Example 1 to purify molybdenum and tungsten from a molybdenum and tungsten mixed acidic solution containing chloride ions, specifically comprising the following steps: A series of mixed acidic solutions containing different concentrations of molybdenum and tungsten were prepared, the pH of the solution was 5, 50 g of the green multifunctional ionic liquid provided in Example 1 was taken and added to 1 L of the mixed solution, respectively, and after shaking at 25° C. for 30 min, the liquid phase was taken and the concentration of each metal ion in the solution was detected by ICP-OES to calculate the purification rate.

[0047] As shown in Table 3, the green multifunctional ionic liquid provided in Example 1 has a very low ability to purify tungsten and molybdenum in an acidic environment. The main reason may be that under acidic conditions, tungsten and molybdenum elements are converted into H 2 MoO 4 、MoO 2 2+ 、、H 2 WO 4 , WO 2 2+ It exists in a non-functional form and cannot be efficiently chelated with green multifunctional ionic liquids.

[0048] Comparative Examples 7-9 Comparative Examples 7-9 respectively provide a method for purifying complex wastewater containing heavy metals using a green multifunctional ionic liquid, using the green multifunctional ionic liquid provided in Example 1 to purify zinc, calcium, and magnesium from a mixed acidic solution of zinc, calcium, and magnesium containing chloride ions, specifically comprising the following steps: A series of mixed acidic solutions containing different concentrations of zinc, calcium and magnesium were prepared, the pH of the solution was 5, 50 g of the green multifunctional ionic liquid provided in Example 1 was taken and added to 1 L of the mixed solution, respectively, and after shaking at 25° C. for 30 min, the liquid phase was taken and the concentration of each metal ion in the solution was detected by ICP-OES to calculate the purification rate.

[0049] As can be seen from Table 4, the green multifunctional ionic liquid provided in Example 1 has extremely low purification capacity for zinc, calcium and magnesium. The main reason may be that the product of the green multifunctional ionic liquid chelated with zinc, calcium and magnesium has good water solubility and cannot be precipitated. When purifying heavy metal wastewater, zinc, calcium and magnesium ions will consume the green multifunctional ionic liquid, and the concentration of zinc, calcium and magnesium ions will affect the purification effect of other heavy metals. Therefore, when treating complex wastewater containing zinc, calcium and magnesium ions, zinc, calcium and magnesium ions can be removed in advance by pretreatment.

[0050] Embodiment 15 This embodiment provides a green multifunctional ionic liquid, the structural formula of which is as follows: The green multifunctional ionic liquid was used to purify complex wastewater containing heavy metals, wherein the wastewater to be treated contained 0.5 g / L of iron (Fe 2+ ), copper (Cu 2+ ), mercury (Hg + ), lead (Pb 2+ ), silver (Ag + ) (the anion is citrate) and 0.001g / L of gold thiosulfate mixed wastewater solution, specifically comprising the following steps: S1. Adjust the pH value of the wastewater solution to 5 with nitric acid; S2. Weigh 50 g of the above-mentioned green multifunctional ionic liquid, put it into 1 L of wastewater solution, shake it in a water bath at 25°C for 30 min, filter and separate the solid phase, collect the liquid phase, and use ICP-OES to detect the concentrations of iron, copper, mercury, lead, gold, and silver ions in the liquid solution, thereby calculating the purification rate of the ionic liquid, wherein the detection error of ICP-OES is ±2%.

[0051] Example 16 This embodiment provides a method for purifying complex wastewater containing heavy metals using a green multifunctional ionic liquid. Compared with Embodiment 15, the only difference is that the structural formula of the green multifunctional ionic liquid is: , other parameters and conditions are basically the same as those in Example 15 and will not be repeated here.

[0052] Embodiment 17 This embodiment provides a method for purifying complex wastewater containing heavy metals using a green multifunctional ionic liquid. Compared with Embodiment 15, the only difference is that the structural formula of the green multifunctional ionic liquid is: , other parameters and conditions are basically the same as those in Example 15 and will not be repeated here.

[0053] It can be seen from Table 5 that ionic liquids in different anion forms have high efficiency in purifying complex wastewater containing heavy metals.

[0054] Embodiment 18 This embodiment provides a method for purifying complex wastewater containing heavy metals using a green multifunctional ionic liquid, wherein the green multifunctional ionic liquid is ; The wastewater to be treated is waste liquid from electronic waste treatment. The metal ions in the wastewater include Fe 2+ , Fe 3+ , Cu + , Cu 2+ , Hg + , Pb 2+ 、Au + 、Au 3+ 、Ag + ; Anions include F - Br - , Cl - ,I - , S 2 O 3 2- , CN - .

[0055] The specific steps include: S1. Adjust the pH value of the wastewater solution to 5 with nitric acid; S2. Weigh 50 g of the above-mentioned green multifunctional ionic liquid, put it into 1 L of wastewater solution, shake it in a water bath at 25°C for 30 min, filter and separate the solid phase, collect the liquid phase, and use ICP-OES to detect the concentrations of iron, copper, mercury, lead, gold, and silver ions in the liquid solution, thereby calculating the purification rate of the ionic liquid, wherein the detection error of ICP-OES is ±2%.

[0056] Embodiment 19 This embodiment provides a method for purifying complex wastewater containing heavy metals with green multifunctional ionic liquids. Compared with Example 18, the only difference is that the wastewater to be treated is a circuit board etching solution, and the metal ions in the wastewater include Fe 2+ , Fe 3+ , Cu + , Cu 2+ , Hg + , Pb 2+ 、Au + 、Au 3+ 、Ag + ; Anions include F - Br - , Cl - ,I - , CN -The other parameters and conditions are basically the same as those in Example 18 and will not be described in detail here.

[0057] Embodiment 20 This embodiment provides a method for purifying complex wastewater containing heavy metals using green multifunctional ionic liquids. Compared with Example 18, the only difference is that the wastewater to be treated is gold cyanide wastewater, and the metal ions in the wastewater include Fe 2+ , Fe 3+ , Cu + , Cu 2+ , Hg + , Pb 2+ 、Au + 、Au 3+ 、Ag + ; Anions include Cl - , CN - The other parameters and conditions are basically the same as those in Example 18 and will not be described in detail here.

[0058] It can be seen from Table 6 that the green multifunctional ionic liquid provided in the present application has a high efficiency in purifying different types of complex wastewater containing heavy metals.

[0059] It should be noted that the present application is not limited to the above-mentioned embodiments. The above-mentioned embodiments are only examples, and the embodiments having the same structure as the technical idea and exerting the same effect within the scope of the technical solution of the present application are all included in the technical scope of the present application. In addition, without departing from the scope of the main purpose of the present application, various modifications that can be thought of by those skilled in the art to the embodiments and other methods of combining some of the constituent elements in the embodiments are also included in the scope of the present application.

Claims

1. A green multifunctional ionic liquid, characterized in that: The general structural formula of the green multifunctional ionic liquid is as follows: ； Wherein, n ≥ 0, X represents the anion of the ionic liquid; The anion of the ionic liquid is F - Br - , Cl - ,I - One or more of .

2. A method for purifying complex wastewater containing heavy metals using green multifunctional ionic liquids, using the green multifunctional ionic liquid of claim 1 to purify complex wastewater containing heavy metals, characterized in that: The following steps are involved: S1. Adjust the pH value of complex wastewater containing heavy metals to a predetermined range; S2. Add the green multifunctional ionic liquid to the complex wastewater containing heavy metals, shake in a water bath for a predetermined time, filter and separate the solid phase, detect the concentration of each metal ion in the liquid phase solution, and calculate the purification rate.

3. The method for purifying complex wastewater containing heavy metals by using green multifunctional ionic liquid according to claim 2, characterized in that: The metal ions in the complex wastewater containing heavy metals include Fe 2+ , Fe 3+ , Cu + , Cu 2+ , Hg + , Pb 2+ 、Au + 、Au 3+ 、Ag + One or more of .

4. The method for purifying complex wastewater containing heavy metals by using green multifunctional ionic liquid according to claim 3, characterized in that: The anions in the complex wastewater containing heavy metals include F - Br - , Cl - ,I - 、S2O3 2- , CN - , citrate or more.

5. The method for purifying complex wastewater containing heavy metals by using green multifunctional ionic liquid according to claim 2, characterized in that: The pH value of the complex wastewater containing heavy metals is 5-13.

6. The method for purifying complex wastewater containing heavy metals by using green multifunctional ionic liquid according to claim 2, characterized in that: The temperature of the water bath shaking is 25-28°C.

7. The method for purifying complex wastewater containing heavy metals by using green multifunctional ionic liquid according to claim 6, characterized in that: The water bath shaking time is 30 to 40 minutes.

8. The method for purifying complex wastewater containing heavy metals by using green multifunctional ionic liquid according to claim 7, characterized in that: The complex wastewater containing heavy metals is one or more of electronic waste treatment waste liquid, circuit board etching liquid, and gold cyanide waste liquid.

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