Extractant and Method for Separating Rhenium from Industrial Wastewater

Abstract

The present application provides an extractant and a method for separating rhenium from industrial wastewater, belonging to the field of heavy metal purification in industrial wastewater. Among them, the extractant uses isosorbide as a raw material, and its binary ring has a V-shaped structure. The V-shaped structure is used as the molecular skeleton of the extractant to introduce a nitrogen atom, and three chain-like aliphatic alkyl groups are connected to the nitrogen atom through a quaternization reaction. By controlling the length of the chain-like aliphatic alkyl group, the directional regulation of the surface hydrophobic ability of the extractant can be realized. The present application is beneficial to the interfacial reaction of the extractant between the organic phase and the inorganic phase by changing the types of derivatized functional groups, the length of the functional group chain segments, the structure of the molecular main chain and its steric hindrance regulation, ensuring the contact between the activation sites in the molecular structure of the extractant in the organic phase and the target metal ions in the inorganic phase, realizing the efficient and selective extraction of rhenium, and avoiding the co-extraction phenomenon of other impurity metal ions to the greatest extent.

Description

Technical Field

[0001] The present invention relates to the technical field of heavy metal purification in industrial wastewater, and specifically relates to an extractant and a method for separating rhenium from industrial wastewater. Background Art

[0002] At present, the mainstream process for purifying heavy metal pollution in water bodies is the extraction method. Due to its simple process operation and strong applicability, the extraction method is widely used in the field of contaminated water body restoration. The technical core of the extraction method is the optimization of the type of extractant. While achieving efficient extraction of target metal ions, it also takes into account the selective extraction of target metal ions. However, the extractants currently used for treating heavy metal-containing wastewater have some limitations, especially in terms of selectivity, and it is difficult to achieve the selective extraction of target metal ions in complex metal solutions. During the extraction stage, a large number of other metal ions are co-extracted, especially the three elements of tungsten, molybdenum, and rhenium are difficult to achieve selective extraction.

[0003] In view of this, it is necessary to design an improved extractant and a method for separating rhenium from industrial wastewater to solve the above problems. Summary of the Invention

[0004] In view of the technical problems existing in the background art, the present application provides an extractant and a method for separating rhenium from industrial wastewater, aiming to solve the technical problem that it is difficult for existing extractants to achieve the selective extraction of target metal ions in complex metal solutions.

[0005] In a first aspect, the present application provides an extractant, and the structural general formula of the extractant is:

[0006]

[0007] where 0 ≤ n ≤ 7.

[0008] In a second aspect, the present application provides a method for separating rhenium from industrial wastewater using the extractant. The extraction is carried out using the extractant described in the first aspect, and includes the following steps:

[0009] Mix the extractant with sulfonated kerosene and dissolve it by ultrasonic treatment to obtain a dilution solution;

[0010] Add a pH regulator to the rhenium-containing wastewater to adjust the pH value of the solution to a predetermined range. Then, add the dilution solution and oscillate it in a water bath for a predetermined time to selectively extract rhenium in the solution;

[0011] Separate the organic phase, detect the concentration of rhenium in the inorganic liquid phase solution, and calculate the extraction rate of the extractant.

[0012] As a further improvement of the present application, the volume ratio of the extractant to the sulfonated kerosene is 1:(10 - 100).

[0013] As a further improvement of the present application, the rhenium exists in the solution in the form of ReO4 - .

[0014] As a further improvement of the present application, the pH regulator is hydrochloric acid.

[0015] As a further improvement of the present application, the rhenium-containing wastewater includes one or more of rhenium-containing ore solution, rhenium-containing catalyst waste liquid and rhenium-containing metallurgical waste liquid.

[0016] As a further improvement of the present application, the predetermined range of the pH value is 1-4.

[0017] As a further improvement of the present application, the temperature of the water bath oscillation is 25-28 °C, and the time is 5-10 min.

[0018] As a further improvement of the present application, the volume ratio of the rhenium-containing wastewater to the diluent is 1:(1-2).

[0019] The beneficial effects of the present application are:

[0020] The present application provides an extractant and a method for separating rhenium from industrial wastewater. The extractant uses isosorbide as a raw material. The presence of oxygen heteroatoms on the V-shaped molecular backbone structure in its molecular structure is beneficial to stabilizing N + , and the endo-OH in the V-shaped molecular backbone structure is beneficial to improving the hydrophilic performance of the extractant. The three chain-like aliphatic alkyl groups directly connected to the N atom, on the basis of realizing the activation of the central site (N + ), by controlling the length of the chain-like aliphatic alkyl groups, the directional regulation of the surface hydrophobic ability of the extractant can be realized.

[0021] By changing the types of derivatized functional groups, the lengths of the functional group segments, the molecular main chain structure and the regulation of its steric hindrance, it is beneficial to the interfacial reaction of the extractant between the organic phase and the inorganic phase, ensuring the contact between the activation sites in the molecular structure of the extractant in the organic phase and the target metal ions in the inorganic phase, and finally realizing the heterogeneous interface-chelation reaction, achieving a qualitative change in the chelation effect of the target metal ions, and then realizing the efficient and selective extraction of rhenium, and avoiding the co-extraction phenomenon of other impurity metal ions to the greatest extent.

[0022] 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 following specific embodiments of the present application are specifically given. Brief Description of the Drawings

[0023] To more clearly illustrate the technical solutions of this application, the accompanying drawings used in this application will be briefly introduced below. Obviously, the accompanying drawings described below are only some embodiments of this application. For those of ordinary skill in the art, without creative efforts, other accompanying drawings can be obtained based on these drawings.

[0024] Figure 1 It is a schematic diagram of the synthesis route of the extractant provided by this application. Specific embodiments

[0025] The embodiments of the technical solutions of this application will be described in detail below in conjunction with the accompanying drawings. The following embodiments are only used to more clearly illustrate the technical solutions of this application, so they are only examples and cannot be used to limit the protection scope of this application.

[0026] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by those of ordinary skill 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" and any variations thereof in the specification and claims of this application and the above accompanying drawing descriptions are intended to cover non-exclusive inclusion.

[0027] 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 two or more, unless otherwise clearly and specifically defined.

[0028] Referring to "embodiments" herein means that the specific features, structures or characteristics described in connection with the embodiments can be included in at least one embodiment of this application. The appearance of this phrase in various positions in the specification 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 explicitly and implicitly understand that the embodiments described herein can be combined with other embodiments.

[0029] In the description of the embodiments of this application, the term "a plurality of" refers to two or more (including two). Similarly, "multiple groups" refers to two or more groups (including two groups), and "multiple pieces" refers to two or more pieces (including two pieces).

[0030] Existing extractants used in the field of treating heavy metal-containing wastewater have certain limitations and are difficult to achieve selective extraction of target metal ions in complex metal solutions. During the extraction stage, a large number of other metal ions are co-extracted, especially the three elements of tungsten, molybdenum, and rhenium are difficult to achieve selective extraction.

[0031] To solve the technical problem that existing extractants are difficult to achieve selective extraction of target metal ions in complex metal solutions, the present application provides an extractant and a method for separating rhenium from industrial wastewater. Among them, the extractant uses isosorbide as a raw material, and its bicyclic ring has a V-shaped structure. The V-shaped structure is introduced as the molecular skeleton of the extractant, and nitrogen atoms are introduced. Through quaternization reaction, three chain-like aliphatic alkyl groups are connected to the N atom, obtaining an extractant with high extraction efficiency for rhenium in wastewater.

[0032] In the first aspect, an embodiment of the present application provides an extractant, and its structural general formula is:

[0033]

[0034] Among them, 0 ≤ n ≤ 7.

[0035] In the technical solution of the embodiment of the present application, the extractant uses isosorbide as a raw material. Isosorbide belongs to a cyclic carbohydrate-derived diol, and its unique three-dimensional spatial structure (the bicyclic ring has a V-shaped structure) results in differences between isosorbide and other cyclic carbohydrate-derived diols. The V-shaped structure is used as the molecular skeleton of the extractant. Utilizing the chemical activity differences of the two hydroxyl groups (endo-OH, exo-OH) in the V-shaped molecular skeleton structure, the exo-OH is derivatized, and then nitrogen atoms are introduced. Through quaternization reaction, it becomes a quaternary ammonium salt, activating the central site (N + ) of the extractant. Due to the presence of oxygen heteroatoms in the V-shaped molecular skeleton structure, it is beneficial to stabilize N + . The endo-OH in the V-shaped molecular skeleton structure is beneficial to improving the hydrophilic property of the extractant. The three chain-like aliphatic alkyl groups directly connected to the N atom, on the basis of activating the central site (N + ), by controlling the length of the chain-like aliphatic alkyl groups (the value of n), the surface hydrophobic ability of the extractant can be directionally regulated. By changing the types of derivatized functional groups, the lengths of the functional group segments, the structure of the molecular main chain, and the regulation of its steric hindrance, it is beneficial to the interfacial reaction between the organic phase and the inorganic phase, ensuring the contact between the activation sites in the molecular structure of the extractant in the organic phase and the target metal ions in the inorganic phase. Finally, a heterogeneous interface-chelation reaction is achieved, realizing a qualitative change in the chelation effect on the target metal ions, and thus achieving the purpose of selectively extracting rhenium.

[0036] The preparation method of the extractant provided by the present application, as Figure 1 shown, includes the following steps:

[0037] S1. Add isosorbide to thionyl chloride solution to prepare an isosorbide solution with a concentration of 0.05 - 0.2 mol / L. Add sodium hydroxide with a concentration of 0.05 - 0.1 mol / L, maintain the system temperature within the range of 0 - 50 °C, react for 24 - 48 h. After the reaction ends, filter and collect the colorless crystal product (Compound A);

[0038] S2. Add sodium cyanide and Compound A to sufficient methanol according to the molar ratio (1 - 1.1):1. Add sodium hydroxide with a concentration of 0.05 - 0.1 mol / L, react at room temperature for 2 - 6 h. After the reaction ends, use rotary evaporation under reduced pressure to remove the methanol solvent. Collect the pale yellow powder, add deionized water, dissolve it by ultrasonic treatment, filter to remove inorganic substances, add methanol and deionized water with a volume ratio of 1:1 for extraction, collect the organic phase, dry it over anhydrous magnesium sulfate, filter, collect the liquid phase, and remove the solvent by rotary evaporation to obtain the white crystal product (Compound B);

[0039] S3. Dissolve Compound B in an excess of anhydrous tetrahydrofuran solution to prepare a Compound B solution with a concentration of 0.05 - 0.2 mol / L. Then dissolve 10 - 50 g of sodium borohydride in anhydrous tetrahydrofuran solution, dissolve it by ultrasonic treatment to prepare a suspension of sodium borohydride. Under the protection of a nitrogen atmosphere, use a constant pressure burette to drop the suspension of sodium borohydride into the Compound B solution. React at room temperature for 2 - 8 h. After the reaction ends, quench it with a tetrahydrofuran - aqueous solution with a volume ratio of 1:1 in an ice - water bath environment. After quenching is completed, filter, collect the liquid, perform vacuum distillation on it to remove the tetrahydrofuran - aqueous solution, and collect the oily solid (Compound C);

[0040] S4. Add Compound C and chloroalkane to anhydrous ethanol according to a molar ratio of 1:(5 - 8), and the molar concentration of chloroalkane is 1 - 1.6 mol / L. React at 50 - 100 °C for 24 - 72 h. After the reaction ends, use rotary evaporation under reduced pressure to remove the solvent. Wash the remaining viscous substance with ether by ultrasonic treatment to remove the excess reactants, filter, collect the solid phase, add deionized water, dissolve it by ultrasonic treatment, recrystallize with acetone, and dry it with liquid nitrogen to obtain the extractant (Compound D).

[0041] In a second aspect, the embodiments of the present application provide a method for separating rhenium from industrial wastewater using the extractant. The extraction is carried out using the extractant described in the first aspect, and the method includes the following steps:

[0042] S1. Mix the extractant with sulfonated kerosene and dissolve it by ultrasonic treatment to obtain a dilution;

[0043] S2. Add a pH regulator to the rhenium - containing wastewater to adjust the pH value of the solution to a predetermined range. Then, add the dilution, shake it in a water bath for a predetermined time to selectively extract rhenium in the solution;

[0044] S3. Separate the organic phase, detect the concentration of rhenium in the inorganic liquid phase solution, and calculate the extraction rate of the extractant.

[0045] Among them, the extraction rate (%) = × 100%;

[0046] In the formula, C0 is the initial concentration of rhenium in the rhenium-containing wastewater before extraction;

[0047] C1 is the remaining concentration of rhenium in the inorganic liquid phase solution after extraction.

[0048] In the technical solution of the embodiment of the present application, by using a specific extractant mixed with sulfonated kerosene, efficient and selective extraction of rhenium can be achieved, interference from other metal ions is reduced, and the specificity of the extraction process is improved; by adjusting the pH value of the solution to a predetermined range, the extraction efficiency of rhenium can be optimized, enabling the extractant to more effectively extract rhenium from the wastewater; the organic phase and the inorganic liquid phase are easily separated, facilitating subsequent treatment and rhenium recovery, improving the efficiency and economic benefits of the entire process; by detecting the concentration of rhenium in the inorganic liquid phase, the extraction rate of the extractant can be accurately calculated, providing reliable data support for process optimization and extractant performance evaluation. This method reduces the need for expensive equipment and complex processes, thereby reducing the cost of treating rhenium-containing wastewater and improving cost-effectiveness.

[0049] Further, in some embodiments, the volume ratio of the extractant to sulfonated kerosene is 1:(10 - 100).

[0050] In the technical solution of the embodiment of the present application, by adjusting the volume ratio of the extractant to sulfonated kerosene, the highest extraction efficiency can be achieved. Sulfonated kerosene, as a diluent, can improve the fluidity of the mixed solution, making the extraction process more uniform, contributing to improving the extraction speed and effect. While ensuring the extraction effect, by increasing the proportion of sulfonated kerosene, the dosage of expensive extractant can be reduced, thereby reducing the treatment cost. In addition, sulfonated kerosene helps to stabilize the extractant and prevent it from decomposing or deteriorating during storage and use. Specifically, the power of ultrasonic dissolution is preferably 50 - 100 W, the ultrasonic frequency is preferably 40 - 60 kHz, and the ultrasonic dissolution time is preferably 15 - 30 min.

[0051] Further, in some embodiments, rhenium exists in the solution in the form of ReO4 - form.

[0052] In the technical solution of the embodiment of the present application, when rhenium exists in the form of ReO4 - form, using the specific extractant of the present application for extraction can form a stable complex with rhenate, thereby achieving efficient extraction of rhenium.

[0053] Further, in some embodiments, the pH regulator is hydrochloric acid, and the predetermined range of the pH value is 1-4.

[0054] In the technical solution of the embodiment of the present application, maintaining the acidity of the solution helps rhenium to exist in the form of soluble perrhenate, preventing rhenium from forming insoluble hydroxides or other precipitates. Specifically, the molar concentration of hydrochloric acid is preferably 0.5-1 mol / L. The extractant provided in the present application has a higher extraction efficiency for ReO4 - in the pH range of 1-4.

[0055] Further, in some embodiments, the rhenium-containing wastewater includes one or more of rhenium-containing ore solutions, rhenium-containing catalyst waste liquids, and rhenium-containing metallurgical waste liquids.

[0056] Specifically, the rhenium-containing wastewater includes one or more of rhenium-containing solutions generated in the hydrometallurgy process of low-grade molybdenum-rhenium sulfide ores, acidic rhenium-containing waste liquids consumed in the catalytic oil refining process using platinum-rhenium catalysts, and rhenium-containing metallurgical waste liquids after acid treatment of the soot generated in the molybdenum pyrometallurgy process.

[0057] In the technical solution of the embodiment of the present application, the extractant has good selectivity and can efficiently extract rhenium from complex waste liquids without reacting with other metal ions in the waste liquids, thereby achieving an efficient and environmentally friendly rhenium ion removal effect and resource recovery.

[0058] Further, in some embodiments, the temperature of the water bath oscillation is 25-28 °C, and the time is 5-10 min.

[0059] In the technical solution of the embodiment of the present application, an appropriate temperature range and oscillation time can enable the extractant to fully contact and react with rhenium ions in the waste liquid, thereby improving the extraction efficiency. Too low a temperature may lead to a slow reaction rate between the extractant and rhenium ions, while too high a temperature may cause a decrease in the selectivity of the extractant or the occurrence of side reactions.

[0060] Further, in some embodiments, the volume ratio of the rhenium-containing wastewater to the diluent is 1:(1-2).

[0061] In the technical solution of the embodiment of the present application, an appropriate volume ratio can ensure that the extractant fully contacts rhenium ions in the wastewater and forms a stable complex, thereby improving the extraction efficiency.

[0062] 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 a limitation to the present application. For those not specified 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 not specified by the manufacturer, they are all conventional products that can be obtained through commercial purchase.

[0063] Example 1

[0064] This example provides an extractant A-1, whose molecular structure is

[0065] , and the extractant A-1 is used to separate rhenium from industrial wastewater, including the following steps:

[0066] S1. Mix the extractant A-1 with sulfonated kerosene at a volume ratio of 1:10, and ultrasonically dissolve it for 15 min under the conditions of an ultrasonic power of 50 W and a frequency of 40 kHz to obtain a dilution;

[0067] S2. Adjust the pH value of the rhenium-containing wastewater to 1 with hydrochloric acid at a molar concentration of 1 mol / L. Then, at room temperature, weigh 100 ml of the above dilution and add it to 50 mL of the rhenium-containing wastewater, and oscillate it in a water bath oscillator at 25 °C for 5 min;

[0068] S3. Separate the organic phase, detect the concentration of rhenium in the inorganic liquid phase solution with ICP-OES (Inductively Coupled Plasma Optical Emission Spectrometer), and calculate the extraction rate of the extractant A-1, where the detection error of ICP-OES is ±2%.

[0069] Examples 2-6 and Comparative Example 1

[0070] Examples 2-6 and Comparative Example 1 respectively provide a method for separating rhenium from industrial wastewater with an extractant. Using the extractant A-1 provided in Example 1 for extraction, compared with Example 1, the only difference is that the pH value of the rhenium-containing wastewater is different. As shown in Table 1, other experimental parameters and conditions are basically the same as those in Example 1 and will not be elaborated here.

[0071]

[0072] As can be seen from Table 1, the extractant A-1 provided in Example 1 has high extraction ability for rhenium within a specific pH range (1-4), and the extraction effect reaches more than 95%. When the pH is greater than 4, part of the rhenium in the liquid phase precipitates and cannot be extracted from the solution system, thus reducing the extraction effect, indicating that the extractant A-1 has a wide application window and is especially suitable for strong acid environments.

[0073] Examples 7-14

[0074] Examples 7-14 respectively provide a method for separating rhenium from industrial wastewater with an extractant. The extractant A-1 provided in Example 1 is used to extract and separate rhenium from various coexisting ion solutions respectively. The specific operation steps are as follows:

[0075] A series of blended solutions containing rhenium and tungsten, molybdenum, iron, and tin in different concentration ratios were prepared. 10 mL of the diluent of extractant A-1 provided in Example 1 was added to each of the above 10 mL blended solutions. After shaking in a water bath at 25°C for 5 min, the inorganic liquid phase was taken, and the concentration of each metal ion in the solution was detected by ICP-OES to calculate the extraction rate. Among them, the detection error of ICP-OES was ±2%, and the extraction effect is shown in Table 2.

[0076]

[0077] As can be seen from Table 2, extractant A-1 has a selective extraction effect on rhenium, without extracting iron and tin metal ions, and the extraction rates for tungsten and molybdenum are less than 10%, ensuring the selective enrichment of rhenium in the extraction solution. Other types of quaternary ammonium salts do not have the above advantages. The main reason is attributed to the unique molecular structure of extractant A-1, where the functionalized functional groups coordinate with each other, resulting in the unique spatial structure of extractant A-1, achieving the effect of efficient selective extraction of rhenium ions, and enabling the selective extraction of complex tungsten, molybdenum, and rhenium solutions.

[0078] Example 15

[0079] This example provides an extractant A-2, whose molecular structure is

[0080] , Using extractant A-2 to separate rhenium from industrial wastewater includes the following steps:

[0081] S1. Mix extractant A-2 and sulfonated kerosene in a volume ratio of 1:10, and dissolve them by ultrasonic treatment to obtain a diluent;

[0082] S2. Adjust the pH value of the rhenium-containing wastewater to 1 with hydrochloric acid. Then, at room temperature, weigh 100 mL of the above diluent and add it to 50 mL of the rhenium-containing wastewater, and shake it in a water bath oscillator at 25°C for 5 min;

[0083] S3. Separate the organic phase, detect the concentration of rhenium in the inorganic liquid phase solution by ICP-OES, and calculate the extraction rate of extractant A-2. Among them, the detection error of ICP-OES is ±2%.

[0084] Examples 16 - 20 and Comparative Example 2

[0085] Examples 16 - 20 and Comparative Example 2 respectively provide a method for separating rhenium from industrial wastewater using an extractant. Extraction is carried out using extractant A-2 provided in Example 15. Compared with Example 15, the only difference is that the pH values of the rhenium-containing wastewater are different, as shown in Table 3. Other experimental parameters and conditions are basically the same as those in Example 15 and will not be elaborated here.

[0086]

[0087] As can be seen from Table 3, the extractant A-2 provided in Example 15 has high extraction ability for rhenium within a specific pH range (1-4), and the extraction effect reaches over 95%. When the pH is greater than 4, part of the rhenium in the liquid phase precipitates and separates from the solution system and cannot be extracted, thus reducing the extraction effect. The extractant A-2 has a wide usage window and is especially suitable for strong acid environments.

[0088] Examples 21-28

[0089] Examples 21-28 respectively provide a method for separating rhenium from industrial wastewater with an extractant. The extractant A-2 provided in Example 15 is used to separately extract and separate rhenium from a solution of multiple coexisting ions. The specific operation steps are as follows:

[0090] A series of blended solutions containing rhenium and tungsten, molybdenum, iron, and tin with different concentration ratios are prepared. 10 mL of the dilution of the extractant A-2 provided in Example 15 is separately added to 10 mL of the blended solution. After shaking for 5 minutes, the inorganic liquid phase is taken, and the concentration of each metal ion in the solution is detected by ICP-OES to calculate the extraction rate. Among them, the detection error of ICP-OES is ±2%. The extraction effect is shown in Table 4.

[0091]

[0092] As can be seen from Table 4, the extractant A-2 has a selective extraction effect on rhenium, and does not extract iron and tin metal ions. The extraction rate of tungsten and molybdenum is less than 5%. Due to the unique molecular structure of the extractant A-2, the functionalized functional groups coordinate with each other, resulting in the unique spatial structure of the extractant A-2, realizing the efficient and selective extraction of rhenium ions.

[0093] Example 29

[0094] This example provides a method for separating rhenium from industrial wastewater with an extractant. The extractant A-2 provided in Example 15 is used for extraction. Compared with Example 15, the only difference is that the temperature of water bath shaking is 28 °C and the time is 10 minutes. Other experimental parameters and conditions are basically the same as those in Example 15 and will not be elaborated here. After testing, the extraction rate of rhenium is 96%.

[0095] Example 30

[0096] This example provides a method for preparing the extractant A-2 in Example 15. The synthesis route diagram is as Figure 1 shown, and specifically includes the following steps:

[0097] S1. Add isosorbide to a sufficient amount of thionyl chloride solution to prepare an isosorbide solution with a concentration of 0.1 mol / L. Add an appropriate amount of sodium hydroxide with a concentration of 0.05 mol / L. Maintain the system temperature within the range of 25 °C and react for 24 h. After the reaction is completed, filter and collect the colorless crystal product (Compound A) with a yield of 93%.

[0098] S2. Add sodium cyanide and Compound A to a sufficient amount of methanol in a molar ratio of 1:1. Add an appropriate amount of sodium hydroxide with a concentration of 0.05 mol / L and react at room temperature for 4 h. After the reaction is completed, use rotary evaporation under reduced pressure to remove the methanol solvent. Collect the pale yellow powder, add deionized water, dissolve it by ultrasonic wave, and filter to remove inorganic substances (alkali, salt). Finally, add methanol and deionized water with a volume ratio of 1:1 for extraction, collect the organic phase, dry it with anhydrous magnesium sulfate, filter, collect the liquid phase, and remove the solvent by rotary evaporation to obtain the white crystal product (Compound B) with a yield of 86%.

[0099] S3. Dissolve Compound B in an excess of anhydrous tetrahydrofuran solution with a concentration of 0.1 mol / L of Compound B at this time. Then dissolve 20 g of sodium borohydride in the anhydrous tetrahydrofuran solution and dissolve it by ultrasonic wave to prepare a suspension of sodium borohydride. Under the protection of a nitrogen atmosphere, use a constant pressure dropping funnel to drop the sodium borohydride tetrahydrofuran suspension into the tetrahydrofuran solution of Compound B and react at room temperature for 4 h. After the reaction is completed, quench it with a tetrahydrofuran-aqueous solution with a volume ratio of 1:1 in an ice-water bath environment. After quenching, filter and collect the liquid, perform vacuum distillation on it to remove the tetrahydrofuran-aqueous solution, and collect the oily solid (Compound C) with a yield of 32%.

[0100] S4. Add Compound C and chlorooctane to anhydrous ethanol in a molar ratio of 1:5. The molar concentration of Compound C is 0.2 mol / L and the molar concentration of chlorooctane is 1 mol / L. React at 60 °C for 48 h. After the reaction is completed, use rotary evaporation under reduced pressure to remove the solvent. Wash the remaining viscous substance with 100 ml of ether by ultrasonic wave to remove the excess reactants and filter. Collect the solid phase, add deionized water, dissolve it by ultrasonic wave, and recrystallize it with acetone. Since the product is an orange-yellow oily substance, perform liquid nitrogen drying to obtain the extractant A-2 (Compound D) with a yield of 37%. Perform a nuclear magnetic resonance hydrogen spectrum test on Compound D. 1 H NMR (deuterated reagent DMSO, 300 MHz): δ 0.50 - 1.00 (9H, CH3), 1.00 - 1.50 (30H, CH2), 1.50 - 2.00 (6H, CH2), 2.50 - 3.00 (1H, CH), 3.00 - 3.50 (8H), 3.50 - 4.00 (5H), 4.00 - 4.50 (3H).

[0101] It should be noted that this application is not limited to the above-described embodiments. The above-described embodiments are merely examples, and embodiments having the same constitution in essence as the technical idea and achieving the same effect within the scope of the technical solution of this application are all included in the technical scope of this application. In addition, within the scope not departing from the gist of this application, various modifications that can be conceived by those skilled in the art 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. An extractant, characterized in that, The structural general formula of the extractant is as follows: Among them, 0 ≤ n ≤ 7.

2. A method for separating rhenium from industrial wastewater by an extractant, which uses the extractant described in claim 1 for extraction, characterized in that, It includes the following steps: Mix the extractant with sulfonated kerosene and dissolve it by ultrasonic treatment to obtain a dilution; Add a pH regulator to the rhenium-containing wastewater to adjust the pH value of the solution to 1-4. Subsequently, add the dilution solution and shake it in a water bath for a predetermined time to selectively extract rhenium in the solution; the rhenium exists in the solution in the form of ReO4 - form; Separate the organic phase, detect the concentration of rhenium in the inorganic liquid-phase solution, and calculate the extraction rate of the extractant.

3. The method for separating rhenium from industrial wastewater by an extractant according to claim 2, characterized in that, The volume ratio of the extractant to the sulfonated kerosene is 1:(10 - 100).

4. The method for separating rhenium from industrial wastewater by an extractant according to claim 2, characterized in that, The pH regulator is hydrochloric acid.

5. The method for separating rhenium from industrial wastewater by an extractant according to claim 2, characterized in that, The rhenium-containing wastewater is one or more of rhenium-containing ore solution, rhenium-containing catalyst waste liquid and rhenium-containing metallurgical waste liquid.

6. The method for separating rhenium from industrial wastewater by an extractant according to claim 2, characterized in that, The temperature of the water bath oscillation is 25 - 28 °C, and the time is 5 - 10 min.

7. The method for separating rhenium from industrial wastewater by an extractant according to claim 2, characterized in that, The volume ratio of the rhenium-containing wastewater to the dilution is 1:(1 - 2).

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