Green Polyfunctional Ionic Liquids and Method for Purifying Complex Wastewater Containing Heavy Metals

Abstract

The present application provides a green multi-functional ionic liquid and a method for purifying heavy metal-containing complex wastewater, belonging to the field of wastewater purification. Among them, the cation of the ionic liquid is ergothioneine and its derivatives, and there is a sulfur-substituted imidazole ring in the molecular skeleton. Under specific conditions, the thioaldehyde group can be converted into a mercapto group, and the mercapto group cooperates with the lone pair electrons on the nitrogen heteroatoms at the 1,3 positions in the aromatic ring to form a potential chelating ligand. The cooperation between the carboxyl group and the quaternary ammonium salt in the main chain structure 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 mercapto group belong to hydrophilic functional groups with different structures, ensuring the hydrophilicity of the ionic liquid under conditions of a wide pH window and being beneficial to the dissolution performance of the ionic liquid. Through the regulation of the anion-cation system of the ionic liquid, as well as the spatial structure of the cation, the types of functional groups and the mutual cooperation between different functional groups in the molecular structure, the high-throughput purification of heavy metal-containing complex wastewater is achieved.

Description

Technical Field

[0001] The present invention relates to the technical field of heavy metal-containing wastewater purification, and particularly relates to a green multi-functional ionic liquid and a method for purifying heavy metal-containing complex wastewater with the same. Background Art

[0002] At present, when purifying industrial wastewater containing heavy metals, precipitants such as sodium sulfide and sodium hydrosulfide are often used. During the use process, sodium hydrosulfide and sodium sulfide are prone to hydrolysis to produce hydrogen sulfide, which poses potential environmental protection and safety problems. In order to solve the limitations of the above-mentioned purifying agents in terms of the environment, scientific research personnel are committed to the development of new green purifying agents. For example, a polyionic gel adsorbent material with an imidazole-long carbon cross-linked molecular structure as the backbone can realize the regulation of the types of functional groups, greatly expanding its application in the field of wastewater treatment and other fields. However, 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 heavy metal-containing solutions, that is, during the adsorption of heavy metal ions, it is difficult to achieve the one-time purification effect of multiple types of target metals; Third, during the derivatization process of the polyionic gel adsorbent material, due to the limitation of the synthesis route, it is impossible to introduce multiple types of functional groups, which limits the applicable fields.

[0003] Ionic liquid is an organic salt that is liquid at room temperature and is composed of organic cations and inorganic or organic anions. As a new type of polar solvent, ionic liquid is also called a "green" chemical solvent because it has almost no vapor pressure, non-flammability, non-volatility, good chemical stability and thermal stability, recyclability and environmental friendliness. Due to the excellent properties of ionic liquid, it is widely used in different aspects of the chemical industry. For example, in chemical separation processes, electrochemistry, and chemical reactions, it is not only an excellent solvent for many reactions but also can be used as a catalyst for reactions. Expanding ionic liquid to the treatment of heavy metal wastewater conforms to the concept of green environmental protection governance.

[0004] In view of this, it is necessary to design an improved green multi-functional ionic liquid and a method for purifying heavy metal-containing complex wastewater with the same to solve the above problems. Summary of the Invention

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

[0006] In the first aspect, the present application provides a green multi-functional ionic liquid, and the structural general formula of the green multi-functional ionic liquid is as follows:

[0007] ;

[0008] Among them, n≥0, X represents an ionic liquid anion;

[0009] The ionic liquid anion is F - , Br - , Cl - , I - or one or more of them.

[0010] In a second aspect, the present application provides a method for purifying heavy metal-containing complex wastewater with a green multi-functional ionic liquid. The green multi-functional ionic liquid described in the first aspect is used to purify heavy metal-containing complex wastewater, including the following steps:

[0011] S1. Adjust the pH value of the heavy metal-containing complex wastewater to a predetermined range;

[0012] S2. Add the green multi-functional ionic liquid to the heavy metal-containing complex wastewater. After shaking in a water bath for a predetermined time, filter and separate the solid phase, detect the concentrations of various metal ions in the liquid phase solution, and calculate the purification rate.

[0013] As a further improvement of the present application, 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 + or one or more of them.

[0014] As a further improvement of the present application, the anions in the heavy metal-containing complex wastewater include F - , Br - , Cl - , I - , S2O3 2- , CN - , or one or more of citrate ions.

[0015] As a further improvement of the present application, the pH value of the heavy metal-containing complex wastewater is 5 to 13.

[0016] As a further improvement of the present application, the temperature of the water bath shaking is 25 to 28 °C, and the time is 30 to 40 min.

[0017] As a further improvement of the present application, the heavy metal-containing complex wastewater is one or more of electronic waste treatment waste liquid, circuit board etching solution, and gold cyanide waste liquid.

[0018] The beneficial effects of the present application are:

[0019] The present application provides a green multi-functional ionic liquid and a method for purifying heavy metal-containing complex wastewater. The cation of the green multi-functional 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 mercapto group. The mercapto group cooperates with the lone pair electrons on the nitrogen heteroatoms at the 1,3 positions in the aromatic ring to form a potential chelating ligand. The main chain structure contains a carboxyl group and a quaternary ammonium salt at the same time. 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 mercapto group belong to hydrophilic functional groups with different structures, which ensure the hydrophilicity of the green multi-functional ionic liquid under conditions of a wide pH window and are conducive to the dissolution performance of the ionic liquid.

[0020] Through the regulation of the anion-cation system of the green multi-functional ionic liquid, as well as the spatial structure of the cation, the types of functional groups and the mutual cooperation between different functional groups in the molecular structure, the high-throughput purification of heavy metal-containing complex wastewater is realized.

[0021] The above description is only an overview of the technical solution of the present application. In order to be able to understand the technical means of the present application more clearly, it can be implemented according to the content of the specification. And in order to make the above and other purposes, features and advantages of the present application more obvious and understandable, the specific embodiments of the present application are specifically given below. Brief Description of the Drawings

[0022] In order to more clearly illustrate the technical solution of the present application, the drawings used in the present application will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present application. For those of ordinary skill in the art, other drawings can be obtained according to these drawings without creative efforts.

[0023] Figure 1 It is the action mechanism of the green multi-functional ionic liquid provided by the present application and the target metal ion and the potential chelating product;

[0024] Figure 2 It is the precipitate generated after the purification of the heavy metal-containing wastewater in Example 1 of the present application;

[0025] Figure 3 It is the physical picture of the wastewater after purification in Examples 5-9 of the present application. Detailed Description of the Specific Embodiments

[0026] The embodiments of the technical solution of the present application will be described in detail below with reference to the drawings. The following embodiments are only used to illustrate the technical solution of the present application more clearly, so they are only examples and cannot be used to limit the protection scope of the present application.

[0027] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the technical field to which this application belongs; the terms used herein are for the purpose of describing specific embodiments only and are not intended to limit this application; the terms "including" and "having" and any variations thereof in the specification and claims of this application and the above drawings are intended to cover non-exclusive inclusion.

[0028] In the description of the embodiments of this application, technical terms such as "first" and "second" are only used to distinguish different objects and cannot be understood as indicating or implying relative importance or implicitly indicating the quantity, specific order or primary-secondary relationship of the indicated technical features. In the description of the embodiments of this application, "a plurality of" means more than two unless otherwise specifically defined.

[0029] Reference to "embodiment" herein means that a particular feature, structure, or characteristic described in connection with the embodiment can be included in at least one embodiment of this application. The phrase appears in various places in the specification and does not necessarily refer to the same embodiment, nor is it an independent or alternative embodiment mutually exclusive with other embodiments. Those skilled in the art will explicitly and implicitly understand that the embodiments described herein can be combined with other embodiments.

[0030] Currently, traditional purifying agents for heavy metals in wastewater, such as sodium sulfide and sodium hydrosulfide precipitants, are prone to hydrolysis to produce harmful gases, which have certain limitations from an environmental protection perspective; while the new polyionic gel adsorption material has a low adsorption flux and it is difficult to achieve the effect of high-throughput purification of complex heavy metal wastewater systems.

[0031] To solve the technical problems of the environmental protection limitations and insufficient high-throughput purification effect existing in the treatment of heavy metals in wastewater by traditional purifying agents, this application provides a green multi-functional ionic liquid and a method for purifying complex heavy metal-containing wastewater. Among them, a stable complex is formed between the ionic liquid with a specific structure and heavy metal ions, so as to achieve the technical effect of high-throughput purification of complex heavy metal-containing wastewater.

[0032] In a first aspect, an embodiment of this application provides a green multi-functional ionic liquid, and its structural general formula is as follows:

[0033] , where n≥0 and X represents the ionic liquid anion.

[0034] The cation of the green multi-functional ionic liquid provided by this application 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 mercapto group. The mercapto group cooperates with the lone pair electrons on the nitrogen heteroatoms at the 1,3 positions in the aromatic ring to form a potential chelating ligand. The main chain structure contains a carboxyl group and a quaternary ammonium salt at the same time. The cooperation between 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, quaternary ammonium salt, and mercapto group belong to hydrophilic functional groups with different structures, ensuring the hydrophilicity of the green multi-functional ionic liquid under conditions of a relatively wide pH window, which is beneficial to the dissolution performance of the ionic liquid.

[0035] Specifically, the anion of the ionic liquid is F - , Br - , Cl - , I - or one or more of them.

[0036] In the technical solution of the embodiment of this application, by adjusting the type of anion of the green multi-functional ionic liquid, the water miscibility property of the ionic liquid can be changed directionally to achieve the interface regulation from the inorganic phase to the organic phase. Through the regulation of the anion-cation system of the green multi-functional 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, the high-throughput purification of heavy metal-containing complex wastewater can be realized.

[0037] In the second aspect, the embodiment of this application provides a method for purifying heavy metal-containing complex wastewater with a green multi-functional ionic liquid. The green multi-functional ionic liquid described in the first aspect is used to purify the heavy metal-containing complex wastewater, including the following steps:

[0038] S1. Adjust the pH value of the heavy metal-containing complex wastewater to a predetermined range;

[0039] S2. Add the green multi-functional ionic liquid to the heavy metal-containing complex wastewater. After shaking 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.

[0040] Among them, adjusting the pH value helps to optimize the adsorption efficiency of the green multi-functional ionic liquid for heavy metal ions. By shaking in a water bath, the contact between the green multi-functional ionic liquid and heavy metal ions can be enhanced to improve the adsorption efficiency. After the shaking is completed, the solid phase containing heavy metal ions (i.e., the complex of the ionic liquid and heavy metal ions) is separated from the liquid phase by filtration, and the metal ion concentration of the filtered liquid phase is detected to evaluate the purification effect; the purification rate is calculated based on the change in the metal ion concentration to quantify the purification effect of the ionic liquid.

[0041] Specifically, the calculation formula for the purification rate of the green multi-functional ionic liquid is:

[0042] Purification rate (%) = 1 - × 100%.

[0043] 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 + or more of them. The anions in the heavy metal-containing complex wastewater include F - , Br - , Cl - , I - , S2O3 2- , CN - , or one or more of citrate ions.

[0044] In the technical solution of the embodiments of the present application, the green multi-functional ionic liquid can effectively remove various heavy metal ions in the wastewater containing various complex anions, reduce environmental pollution, and protect water resources; at the same time, this method has the advantages of simple operation and high purification efficiency, and has good application prospects. Specifically, taking Cl - as the ionic liquid anion as an example, the chelation mechanism between the green multi-functional ionic liquid and metal ions and the potential chelation products are as Figure 1 shown, where a, b, c, d, e, f are the 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.

[0045] Furthermore, in some embodiments, the pH value of the heavy metal-containing complex wastewater is 5 - 13.

[0046] In the technical solution of the embodiments of the present application, the appropriate pH value can affect the adsorption performance of the green multi-functional ionic liquid and the existing forms of heavy metal ions, thereby affecting the interaction between the ionic liquid and heavy metal ions. The appropriate pH value helps to improve the capturing ability of the ionic liquid for heavy metal ions and ensure that the wastewater purification effect reaches the expected goal.

[0047] Furthermore, in some embodiments, the temperature of the water bath oscillation is 25 - 28 °C, and the time is 30 - 40 min.

[0048] In the technical solution of the embodiment of the present application, at an appropriate temperature, the interaction between the green multi-functional ionic liquid and heavy metal ions can reach an equilibrium state, thereby optimizing the adsorption efficiency. An appropriate oscillation time can ensure that the ionic liquid has sufficient time to contact and react with the heavy metal ions in the wastewater, improving the purification rate.

[0049] Further, in some embodiments, the heavy metal-containing complex wastewater is one or more of electronic waste treatment waste liquid, circuit board etching solution, and gold cyanide waste liquid.

[0050] In the technical solution of the embodiment of the present application, the green multi-functional ionic liquid has wide applicability and is suitable for various heavy metal-containing wastewaters. The special functional groups contained in the green multi-functional ionic liquid can coordinate and complex with different metal ions, thereby effectively adsorbing and stabilizing heavy metal ions. At the same time, the green multi-functional ionic liquid can adapt to wastewaters with a large difference in heavy metal concentration. In the case of a low heavy metal content, a relatively small amount of the green multi-functional ionic liquid can achieve the treatment effect; while in the case of a high heavy metal content, the dosage of the green multi-functional ionic liquid needs to be increased. In addition, the purification rate can also be improved through multiple purifications, and the treatment effect and economic cost are balanced according to the specific situation in actual applications.

[0051] The following lists some specific embodiments. 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 a limitation of the present application. For those without specific techniques or conditions noted in the embodiments, the techniques or conditions described in the literature in the field or according to the product specifications are followed. For reagents or instruments without the manufacturer noted, they are all conventional products that can be obtained through commercial purchase.

[0052] Example 1

[0053] This embodiment provides a green multi-functional ionic liquid, and its structural formula is as follows:

[0054] , using this green multi-functional ionic liquid to purify heavy metal-containing complex wastewater, wherein the wastewater to be treated is a wastewater solution containing 0.5 g / L of iron (Fe 2+ ), copper (Cu 2+ ), mercury (Hg + ), lead (Pb 2+ ), silver (Ag + ) (the anion is citrate) and 0.001 g / L of gold thiosulfate mixed, and the specific steps are as follows:

[0055] S1. Adjust the pH value of the wastewater solution to 5 with nitric acid;

[0056] S2. Weigh 50 g of the above-mentioned green multi-functional ionic liquid and put it into 1 L of the 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 Figure 2 shown. Collect the liquid phase and use ICP-OES (Inductively Coupled Plasma Optical Emission Spectrometer) to detect the concentrations of iron, copper, mercury, lead, gold, and silver ions in the liquid-phase solution, and then calculate the purification rate of the ionic liquid. Among them, the detection error of ICP-OES is ±2%.

[0057] Example 2

[0058] Example 2 provides a method for purifying heavy-metal-containing complex wastewater with a green multi-functional ionic liquid. Compared with Example 1, the only difference is that the temperature of the water-bath shaking is 28 °C and the time is 40 min. Other parameters and conditions are basically the same as those in Example 1 and will not be elaborated here.

[0059] Examples 3 - 10 and Comparative Example 1

[0060] Examples 3 - 10 and Comparative Example 1 respectively provide a method for purifying heavy-metal-containing complex wastewater with a green multi-functional ionic liquid. Compared with Example 1, the only difference is that the pH value of the wastewater solution is adjusted differently with nitric acid or sodium hydroxide, as shown in Table 1. Other parameters and conditions are basically the same as those in Example 1 and will not be elaborated here.

[0061]

[0062] As can be seen from Table 1, the green multi-functional 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 - 13, the purification ability is higher than 90%. The reason is that the special molecular structure of the green multi-functional ionic liquid can chelate with a variety of target metal ions, and the hydrolysis performance of the chelation product becomes poor, generating a precipitate and separating from the solution system. Figure 3 This is a physical picture of the purified wastewater in Examples 5 - 9 of this application. It can be seen that the bottom of the container is the chelation 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 into imidazole mercapto group, and the activation site S- is difficult to be activated, resulting in hindrance to the subsequent chelation reaction. When pH > 13, metal ions such as iron and copper precipitate spontaneously in the above solution, and it is difficult to prepare iron, copper, mercury, lead, and silver ion solutions with specific concentrations.

[0063] Examples 11 - 14 and Comparative Examples 2 - 3

[0064] Examples 11 - 14 and Comparative Examples 2 - 3 respectively provide a method for purifying heavy metal - containing complex wastewater with a green multi - functional ionic liquid. Compared with Example 1, the difference is only that the pH value of the wastewater solution is adjusted to 9, and different masses of the green multi - functional ionic liquid are added respectively, as shown in Table 2. Other parameters and conditions are basically the same as those in Example 1 and will not be elaborated here.

[0065]

[0066] As can be seen from Table 2, the green multi - functional ionic liquid provided in Example 1 requires a specific addition amount range for purifying wastewater containing iron, copper, mercury, lead, gold, and silver ions. Considering the economic cost, the optimal dosage range of the reagent is between 15 - 90 g, and the purification rate of each metal ≥ 80%. As the addition amount continues to increase, since the chelates of each metal are slightly soluble in water themselves, the purification rate of each metal no longer increases.

[0067] Comparative Examples 4 - 6

[0068] Comparative Examples 4 - 6 respectively provide a method for purifying heavy metal - containing complex wastewater with a green multi - functional ionic liquid. Using the green multi - functional ionic liquid provided in Example 1, molybdenum and tungsten are respectively purified from a co - mixed acidic solution of molybdenum and tungsten containing chloride ions, which specifically includes the following steps:

[0069] Prepare a series of co - mixed acidic solutions containing different concentrations of molybdenum and tungsten, with the pH of the solution being 5. Take 50 g of the green multi - functional ionic liquid provided in Example 1 and add it to 1 L of the co - mixed solution respectively. After shaking at 25 °C for 30 min, take the liquid phase and detect the concentration of each metal ion in the solution by ICP - OES to calculate the purification rate.

[0070]

[0071] As can be seen from Table 3, the green multi - functional ionic liquid provided in Example 1 has extremely low purification ability for tungsten and molybdenum in an acidic environment. The main reason may be that under acidic conditions, tungsten and molybdenum elements exist in the forms of H2MoO4, MoO2 2+ ,, H2WO4, WO2 2+ and cannot chelate efficiently with the green multi - functional ionic liquid.

[0072] Comparative Examples 7 - 9

[0073] Comparative Examples 7 - 9 respectively provide a method for purifying heavy metal - containing complex wastewater with a green multi - functional ionic liquid. Using the green multi - functional ionic liquid provided in Example 1, zinc, calcium, and magnesium are respectively purified from a co - mixed acidic solution of zinc, calcium, and magnesium containing chloride ions, which specifically includes the following steps:

[0074] Prepare a series of blended acidic solutions containing different concentrations of zinc, calcium, and magnesium, with the pH of the solution being 5. Take 50 g of the green multi-functional ionic liquid provided in Example 1 and add it to 1 L of the blended solution respectively. After shaking at 25 °C for 30 min, take the liquid phase and use ICP-OES to detect the concentration of each metal ion in the solution, and then calculate the purification rate.

[0075]

[0076] As can be seen from Table 4, the green multi-functional ionic liquid provided in Example 1 has extremely low purification ability for zinc, calcium, and magnesium. The main reason may be that the product after chelation of the green multi-functional ionic liquid with zinc, calcium, and magnesium has good water solubility and cannot precipitate. When purifying heavy metal wastewater, zinc, calcium, and magnesium ions will consume the green multi-functional 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 through pretreatment.

[0077] Example 15

[0078] This example provides a green multi-functional ionic liquid, and its structural formula is as follows:

[0079] , and use this green multi-functional ionic liquid to purify complex heavy metal wastewater. Among them, the wastewater to be treated is a wastewater solution containing 0.5 g / L of iron (Fe 2+ ), copper (Cu 2+ ), mercury (Hg + ), lead (Pb 2+ ), silver (Ag + ) (the anion is citrate) and 0.001 g / L of gold thiosulfate mixed, and specifically includes the following steps:

[0080] S1. Adjust the pH value of the wastewater solution to 5 with nitric acid;

[0081] S2. Weigh 50 g of the above green multi-functional ionic liquid, put it into 1 L of the wastewater solution, shake it in a water bath at 25 °C for 30 min, then filter and separate the solid phase, collect the liquid phase, and use ICP-OES to detect the concentration of iron, copper, mercury, lead, gold, and silver ions in the liquid phase solution, so as to calculate the purification rate of the ionic liquid, where the detection error of ICP-OES is ±2%.

[0082] Example 16

[0083] This example provides a method for purifying complex heavy metal wastewater with a green multi-functional ionic liquid. Compared with Example 15, the difference is only that the structural formula of the green multi-functional ionic liquid is:

[0084] , other parameters and conditions are basically the same as those in Example 15, and will not be elaborated here.

[0085] Example 17

[0086] This example provides a method for purifying heavy metal-containing complex wastewater with a green multi-functional ionic liquid. Compared with Example 15, the only difference is that the structural formula of the green multi-functional ionic liquid is:

[0087] , other parameters and conditions are basically the same as those in Example 15, and will not be elaborated here.

[0088]

[0089] As can be seen from Table 5, ionic liquids with different anion forms all have high purification ability for heavy metal-containing complex wastewater.

[0090] Example 18

[0091] This example provides a method for purifying heavy metal-containing complex wastewater with a green multi-functional ionic liquid. Among them, the green multi-functional ionic liquid is ; the wastewater to be treated is electronic waste treatment waste liquid, and the metal ions in the wastewater include Fe 2+ , Fe 3+ , Cu + , Cu 2+ , Hg + , Pb 2+ , Au + , Au 3+ , Ag + ; the anions include F - , Br - , Cl - , I - , S2O3 2- , CN - .

[0092] Specifically, it includes the following steps:

[0093] S1. Adjust the pH value of the wastewater solution to 5 with nitric acid;

[0094] S2. Weigh 50 g of the above-mentioned green multi-functional ionic liquid, put it into 1 L of the wastewater solution, shake it in a water bath at 25 °C for 30 min, then 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 phase solution, so as to calculate the purification rate of the ionic liquid. Among them, the detection error of ICP-OES is ±2%.

[0095] Example 19

[0096] This embodiment provides a method for purifying heavy metal-containing complex wastewater with a green multi-functional ionic liquid. Compared with Embodiment 18, the only difference is that the wastewater to be treated is 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 + ; the anions include F - 、Br - 、Cl - 、I - 、CN - . Other parameters and conditions are basically the same as those in Embodiment 18 and will not be elaborated here.

[0097] Embodiment 20

[0098] This embodiment provides a method for purifying heavy metal-containing complex wastewater with a green multi-functional ionic liquid. Compared with Embodiment 18, the only difference is that the wastewater to be treated is cyanide waste liquid of gold, and the metal ions in the wastewater include Fe 2+ 、Fe 3+ 、Cu + 、Cu 2+ 、Hg + 、Pb 2+ 、Au + 、Au 3+ 、Ag + ; the anions include Cl - 、CN - . Other parameters and conditions are basically the same as those in Embodiment 18 and will not be elaborated here.

[0099]

[0100] As can be seen from Table 6, the green multi-functional ionic liquid provided by this application has high purification ability for different types of heavy metal-containing complex wastewater.

[0101] It should be noted that this application is not limited to the above embodiments. The above embodiments are only examples, and embodiments with the same composition and the same function and effect as the technical idea within the technical solution scope of this application are all included in the technical scope of this application. In addition, within the scope not departing from the main idea of this application, various deformations that can be thought of by those skilled in the art are applied to the embodiments, and other ways constructed by combining some constituent elements in the embodiments are also included in the scope of this application.

Claims

1. A method for purifying complex wastewater containing heavy metals with a green multi-functional ionic liquid, characterized in that, It includes the following steps: S1. Adjust the pH value of the heavy metal-containing complex wastewater to a predetermined range; S2. Add a green multi-functional ionic liquid to the heavy metal-containing complex wastewater. After shaking 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. The structural general formula of the green multi-functional ionic liquid is as follows: ； where n≥0, and X represents the ionic liquid anion; The ionic liquid anion is F - , Br - , Cl - , I - or one or more of them; The metal ions in the heavy metal-containing complex wastewater include Au + , Au 3+ and one or more of them.

2. The method for purifying heavy metal-containing complex wastewater by using a green multi-functional ionic liquid according to claim 1, characterized in that, The anions in the heavy metal-containing complex wastewater include F - , Br - , Cl - , I - , S2O3 2- , CN - and one or more of citrate ions.

3. The method for purifying heavy metal-containing complex wastewater with green polyfunctional ionic liquid according to claim 1, wherein The pH value of the heavy metal-containing complex wastewater is 5-13.

4. The method for purifying heavy metal-containing complex wastewater by using a green multi-functional ionic liquid according to claim 1, wherein The temperature of the water bath shaking is 25-28°C.

5. The method for purifying heavy metal-containing complex wastewater by using a green multi-functional ionic liquid according to claim 4, wherein The time of the water bath shaking is 30-40 min.

6. The method for purifying heavy metal-containing complex wastewater by using a green multi-functional ionic liquid according to claim 5, characterized in that, The heavy metal-containing complex wastewater is one or more of electronic waste treatment waste liquid, circuit board etching solution, and gold cyanide waste liquid.

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