Composite extractant and method for separating gold from electroplating wastewater by using composite extractant

Abstract

The invention provides a composite extraction agent and a method for separating gold in electroplating wastewater by using the composite extraction agent, and belongs to the field of wastewater purification, the composite extraction agent comprises an extraction main agent and an extraction main agent stabilizer, the extraction main agent is a diallyl sulfide compound, and the extraction main agent stabilizer is dithiothreitol. The extraction main agent can form a stable complex with gold ions to enter an organic phase, and a nonlinear space structure of the extraction main agent can realize selective coordination with the gold ions, so that coordination reaction with other impurity metal ions is avoided; the sulfydryl in the dithiothreitol molecular structure has reducibility, so that the residual oxidant or dissolved oxygen in the solution can be prevented from oxidizing the extraction main agent, and the nonlinear polysulfide structure of the extraction main agent is kept. According to the method, the heterogeneous interface-coordination reaction of the activation sites in the molecular structure of the extracting agent and the gold ions in the inorganic phase is ensured by regulating and controlling the multi-component components of the composite extracting agent, efficient selective chelation of target metal is achieved, and the purpose of separating and enriching the gold ions in the gold-containing electroplating waste liquid is achieved.

Description

Technical Field

[0001] The invention relates to the technical field of heavy metal purification in industrial electroplating wastewater, and in particular to a composite extractant and a method for separating gold in electroplating wastewater. Background Art

[0002] At present, the treatment methods for heavy metal gold in industrial wastewater mainly include: chemical precipitation, oxidation-reduction, solvent extraction, adsorption, membrane separation, ion exchange, etc. Among them, the solution extraction method can achieve the separation and enrichment of the target metal. Due to its simple operation, good continuity, high separation efficiency and low energy consumption, it has good industrial prospects and is widely used in the field of remediation of polluted water bodies. The core of the extraction method is the screening of the type of extractant. On the basis of achieving efficient extraction of the target metal ions, it is necessary to take into account the selective extraction of the target metal ions and avoid the co-extraction of impurity metals.

[0003] In the field of treating gold-containing electroplating wastewater, the currently used extractants have certain limitations, mainly manifested in that impurity metals are easily co-extracted and have poor selectivity, making it difficult to achieve selective extraction of gold from gold-containing electroplating wastewater.

[0004] In view of this, it is necessary to design an improved composite extractant and a method for separating gold from electroplating wastewater 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 composite extractant and a method for separating gold from electroplating wastewater, aiming to solve the technical problem that the existing extractants have poor selectivity when treating gold-containing electroplating wastewater.

[0006] In a first aspect, the present application provides a composite extractant, comprising an extraction main agent and an extraction main agent stabilizer, wherein the extraction main agent is a diallyl sulfide compound, and the extraction main agent stabilizer is dithiothreitol; the mass ratio of the extraction main agent to the extraction main agent stabilizer is (9~99):1.

[0007] As a further improvement of the present application, the diallyl sulfide compound is or .

[0008] In a second aspect, an embodiment of the present application provides a method for separating gold from electroplating wastewater using a composite extractant, wherein the composite extractant described in the first aspect is used for extraction, comprising the following steps: The extracting agent and the extracting agent stabilizer are mixed, and a diluent is added to dissolve by ultrasonication to obtain an extracting agent diluent; A pH adjuster is added to the gold-containing wastewater to adjust the pH value of the solution to 1-6, and then the extractant diluent is added to achieve selective extraction of gold in the solution.

[0009] As a further improvement of the present application, the diluent is sulfonated kerosene.

[0010] As a further improvement of the present application, the mass ratio of the total mass of the extraction main agent and the extraction main agent stabilizer to the mass ratio of the diluent is 1:(9~29).

[0011] As a further improvement of the present application, the pH regulator is hydrochloric acid.

[0012] As a further improvement of the present application, the gold-containing wastewater is one or more of mineral resource solution, catalyst waste liquid, and metallurgical waste liquid.

[0013] As a further improvement of the present application, the gold is in the solution as AuCl4 - Form exists.

[0014] As a further improvement of the present application, the volume ratio of the gold-containing wastewater to the extractant dilution solution is 1:(1~2).

[0015] The beneficial effects of this application are: The present application provides a composite extractant and a method for separating gold from electroplating wastewater. The composite extractant includes an extracting agent and an extracting agent stabilizer. The extracting agent is a diallyl sulfide compound, and the extracting agent stabilizer is dithiothreitol. The extracting agent can form a stable complex with gold ions and enter the organic phase. In addition, the nonlinear spatial structure of the diallyl sulfide compound can achieve selective coordination with gold ions, avoiding coordination reactions with other impurity metal ions. The thiol group (-SH) in the molecular structure of dithiothreitol is reducing, which can prevent the residual oxidant or dissolved oxygen in the solution from oxidizing the extracting agent, and maintain the nonlinear polysulfide structure of the extracting agent. By regulating the multi-component components of the composite extracting agent, the heterogeneous interface-coordination reaction between the activation sites in the molecular structure of the extracting agent and the gold ions in the inorganic phase is guaranteed, and the efficient selective chelation of the target metal is achieved, so as to achieve the purpose of separation-enrichment of gold ions in gold-containing electroplating waste liquid.

[0016] 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. DETAILED DESCRIPTION

[0017] The following is a detailed description of the embodiments of the technical solution of the present application. 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.

[0018] 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 description and claims of this application and any variations thereof are intended to cover non-exclusive inclusions.

[0019] 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.

[0020] 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.

[0021] In the description of the embodiments of the present application, the term "multiple" refers to more than two (including two). Similarly, "multiple groups" refers to more than two groups (including two groups), and "multiple pieces" refers to more than two pieces (including two pieces).

[0022] The extractants currently used in the field of gold-containing electroplating wastewater treatment have certain limitations: impurity metals are easily co-extracted during the extraction process, and the selectivity for the target metal is poor, making it difficult to achieve selective extraction of gold from gold-containing electroplating wastewater.

[0023] In order to solve the technical problem that existing extractants are difficult to achieve selective extraction of gold in gold-containing electroplating wastewater, the present application provides a composite extractant and a method for separating gold in electroplating wastewater, wherein the composite extractant includes an extraction main agent and an extraction main agent stabilizer, the extraction main agent is a diallyl sulfide compound, and the extraction main agent stabilizer is dithiothreitol. By regulating the multi-components of the composite extractant, the heterogeneous interface-coordination reaction between the activation sites in the molecular structure of the extractant and the gold ions in the inorganic phase is guaranteed, thereby achieving efficient selective chelation of the target metal and achieving the purpose of separating and enriching gold ions in gold-containing electroplating wastewater.

[0024] In a first aspect, an embodiment of the present application provides a composite extractant, comprising an extraction main agent and an extraction main agent stabilizer, wherein the extraction main agent is a diallyl sulfide compound, and the extraction main agent stabilizer is dithiothreitol; the mass ratio of the extraction main agent to the extraction main agent stabilizer is (9~99):1.

[0025] In the technical solution of the embodiment of the present application, according to Pearson's hard and soft acid-base theory, the sulfur in the polysulfide bond in the sulfide compound is an electron donor (soft base), while the gold (I) ion as an electron acceptor is a soft acid, and the gold (III) ion has a large electron cloud deformability and the ability to accept electrons, which is between soft acid and hard acid. According to the hard and soft acid-base theory, the diallyl sulfide compound extraction main agent can form a stable complex with gold ions and enter the organic phase. In addition, the nonlinear spatial structure of the diallyl sulfide compound can achieve selective coordination with gold ions, avoiding coordination reactions with other impurity metal ions.

[0026] The main extractant stabilizer in the composite extractant is dithiothreitol, and its molecular structure is The thiol group (-SH) in the molecular structure of dithiothreitol is reducing, which can prevent the residual oxidant or dissolved oxygen in the solution from oxidizing the main extractant and maintain the nonlinear polysulfide structure of the main extractant.

[0027] By adjusting the ratio of the main extractant to the main extractant stabilizer, it is possible to ensure that the composite extractant has a high extraction capacity and stability when treating gold-containing wastewater. An appropriate ratio of the main extractant to the main extractant stabilizer helps to improve the selectivity for gold ions and reduce the co-extraction of other metal ions, thereby improving the purity of the final product. A too high ratio of the main extractant stabilizer may reduce the capacity of the extractant, while a too low ratio of the main extractant stabilizer may not be enough to protect the main extractant, affecting its stability and service life, and further affecting the extraction efficiency. By optimizing the ratio, the amount of the main extractant can be reduced and the treatment cost can be reduced.

[0028] Further, in some embodiments, the diallyl sulfide compound is or .

[0029] In the technical solution of the embodiment of the present application, the diallyl sulfide compound is (diallyl disulfide) or (Diallyl trisulfide), these two compounds, due to their special molecular structure, can improve the selective extraction of gold, thereby reducing the co-extraction of impurity metals in the treatment of gold-containing electroplating wastewater and improving the gold recovery efficiency.

[0030] In a second aspect, an embodiment of the present application provides a method for separating gold from electroplating wastewater using a composite extractant, wherein the composite extractant described in the first aspect is used for extraction, comprising the following steps: S1. The extracting agent and the extracting agent stabilizer are mixed, and a diluent is added and ultrasonically dissolved to obtain an extracting agent diluent; S2. Add a pH adjuster to the gold-containing wastewater to adjust the pH value of the solution to 1-6, and then add an extractant diluent to achieve selective extraction of gold in the solution.

[0031] In the technical scheme of the embodiment of the present application, by using a diallyl sulfide compound as the main extraction agent and mixing it with the main extraction agent stabilizer, the selectivity for gold ions can be significantly improved and the co-extraction of other metal ions can be reduced. The addition of the main extraction agent stabilizer helps to protect the main extraction agent from oxidation or hydrolysis, thereby extending the service life of the extractant. By adjusting the pH value of the solution to acidity, it can be ensured that the extraction process is carried out under optimal conditions. Specifically, the extractant diluent is added to the gold-containing wastewater, and the water bath is oscillated at 25~28℃ for 5~10min to selectively extract the gold in the solution. After the extraction is completed, the organic phase is separated, the concentration of gold in the inorganic liquid phase solution is detected, and the extraction rate is calculated. This method can reduce the use of harmful chemicals, while improving the recovery rate of gold and reducing resource waste. Through effective gold extraction and recovery, the recovery value of gold in electroplating wastewater can be improved and the treatment cost can be reduced.

[0032] Further, in some embodiments, the diluent is sulfonated kerosene.

[0033] In the technical solution of the embodiment of the present application, the sulfonated kerosene has good compatibility with the composite extractant and can effectively dilute and disperse the main extraction agent to form a stable extraction system.

[0034] Furthermore, in some embodiments, the mass ratio of the total mass of the extraction agent and the extraction agent stabilizer to the mass ratio of the diluent is 1:(9-29).

[0035] In the technical solution of the embodiment of the present application, the appropriate amount of diluent can ensure that the main extracting agent is fully dispersed in the diluent, thereby increasing the contact area with the gold-containing wastewater and enhancing the extraction efficiency. The proportion of the diluent will affect the density and separation effect of the two phases (organic phase and aqueous phase). Too little or too much diluent may affect the efficiency of phase separation.

[0036] Further, in some embodiments, the pH adjuster is hydrochloric acid.

[0037] In the technical solution of the embodiment of the present application, by adding hydrochloric acid, the pH value of the solution can be quickly adjusted to a suitable acidic range to promote the reaction between gold ions and the extractant. Under acidic conditions, the activity of other metal ions may be reduced, thereby reducing the interaction between other metals and the extractant and improving the selective extraction of gold.

[0038] Furthermore, in some embodiments, the gold-containing wastewater is one or more of mineral resource solution, catalyst waste liquid, and metallurgical waste liquid.

[0039] In the technical solution of the embodiment of the present application, the composite extractant can adapt to the treatment requirements of gold-containing wastewater from different sources and has good selectivity.

[0040] Further, in some embodiments, gold is in the form of AuCl4 - Form exists.

[0041] In the technical solution of the embodiment of the present application, under acidic conditions, gold can be converted into AuCl4 - This form is more likely to form a stable complex with the diallyl sulfide compound in the composite extractant, thereby improving the selective extraction of gold.

[0042] Furthermore, in some embodiments, the volume ratio of gold-containing wastewater to extractant dilution solution is 1:(1~2).

[0043] In the technical solution of the embodiment of the present application, the appropriate volume ratio can ensure that the extractant is in full contact with the gold ions in the gold-containing wastewater, thereby improving the gold extraction efficiency.

[0044] 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.

[0045] Example 1 This embodiment provides a composite extractant, including an extracting agent and an extracting agent stabilizer, wherein the extracting agent is diallyl disulfide, and the extracting agent stabilizer is dithiothreitol. The composite extractant is used to separate gold from electroplating wastewater, and the specific steps are as follows: S1. The extracting agent and the extracting agent stabilizer are mixed in a mass ratio of 9:1, the total mass of the extracting agent and the extracting agent stabilizer is mixed with sulfonated kerosene in a mass ratio of 1:9, and ultrasonically dissolved to obtain an extracting agent diluent; S2. Take 100mL of industrial electroplating wastewater containing gold ions, add hydrochloric acid to adjust the pH value to 1, add 100ml of extractant diluent, shake in a water bath oscillator at 25°C for 5 minutes, separate the organic phase, and use ICP-OES (inductively coupled plasma emission spectrometer) to detect the concentration of gold ions in the inorganic liquid phase solution, thereby calculating the extraction rate of the composite extractant, where the detection error of ICP-OES is ±2%.

[0046] Examples 2-6 and Comparative Example 1 Examples 2-6 and Comparative Example 1 respectively provide a method for separating gold from electroplating wastewater using a composite extractant. The composite extractant provided in Example 1 is used for extraction. Compared with Example 1, the only difference is that the pH value of the gold-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 repeated here.

[0047] As shown in Table 1, the composite extractant provided in Example 1 has a high efficiency in extracting gold in a specific pH range (1-6), and the extraction effect is more than 90%. When the pH value is greater than 7, the gold ions in the liquid phase are precipitated as Au(OH)3, the gold ions are separated from the solution system, and the gold ions in the solid phase cannot achieve the target ion interface migration, which leads to ineffective extraction. The composite extractant has a wide use window, and is particularly suitable for a strong acid environment with a pH value of 1-4. The gold extraction rate in a strong acid environment is greater than 95%.

[0048] Comparative Example 2 Comparative Example 2 provides a method for separating gold from electroplating wastewater using a composite extractant. Compared with Example 1, the only difference is that the composite extractant used does not contain an extractant stabilizer. Other experimental parameters and conditions are basically the same as those in Example 1 and will not be repeated here.

[0049] Comparative Examples 3-8 Comparative Examples 3-8 respectively provide a method for separating gold from electroplating wastewater using a composite extractant. Compared with Comparative Example 2, the only difference is that the pH value of the gold-containing wastewater is different, as shown in Table 2. Other experimental parameters and conditions are basically the same as those of Comparative Example 2 and will not be repeated here.

[0050] As shown in Table 2, the extractant stabilizer plays an important role in the composite extractant. The thiol (-SH) in the molecular structure of the extractant stabilizer (dithiothreitol) is reducing, which can prevent the residual oxidant or dissolved oxygen in the solution from oxidizing the extractant and maintain its chemical stability. When the composite extractant system is complete in type and the dosage is reasonable, the synergistic effect between the reagents of each functional unit can achieve efficient gold extraction.

[0051] Embodiment 7-14 Examples 7-14 respectively provide a method for separating gold from electroplating wastewater using a composite extractant, wherein the composite extractant provided in Example 1 is used to extract and separate gold from a variety of coexisting ion solutions, and the specific operation steps are as follows: A series of mixed solutions containing different concentration ratios of gold, tungsten, molybdenum, rhenium and copper were prepared. 50 ml of the extractant dilution provided in Example 1 was added to 50 ml of the mixed solution, respectively, and after shaking 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, wherein the detection error of ICP-OES was ±2%, and the extraction effect was shown in Table 3.

[0052] As shown in Table 3, the composite extractant has a selective extraction effect on gold, but will not extract tungsten, molybdenum, rhenium, copper metal ions, especially copper ions, which ensures the selective separation and enrichment of gold by the composite extractant. Other types of polysulfide types do not have the above advantages. The main reasons are: first, the unique nonlinear molecular spatial structure of the main extractant achieves the selective extraction of gold ions; second, the components of the specific composite extractant cooperate with each other to achieve the effect of efficient extraction of gold ions, and finally realize the efficient selective extraction of gold-containing wastewater.

[0053] 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 composite extractant, comprising an extracting agent and an extracting agent stabilizer, characterized in that: The main extraction agent is a diallyl sulfide compound, and the main extraction agent stabilizer is dithiothreitol; the mass ratio of the main extraction agent to the main extraction agent stabilizer is (9-99):

1.

2. The composite extractant according to claim 1, characterized in that The diallyl sulfide compound is or .

3. A method for separating gold from electroplating wastewater using a composite extractant, wherein the composite extractant according to claim 1 is used for extraction, characterized in that: The following steps are involved: The extracting agent and the extracting agent stabilizer are mixed, and a diluent is added and ultrasonically dissolved to obtain an extracting agent diluent; A pH adjuster is added to the gold-containing wastewater to adjust the pH value of the solution to 1-6, and then the extractant diluent is added to achieve selective extraction of gold in the solution.

4. The method for separating gold from electroplating wastewater using a composite extractant according to claim 3, characterized in that: The diluent is sulfonated kerosene.

5. The method for separating gold from electroplating wastewater using a composite extractant according to claim 4, characterized in that: The mass ratio of the total mass of the extraction main agent and the extraction main agent stabilizer to the mass ratio of the diluent is 1:(9-29).

6. The method for separating gold from electroplating wastewater using a composite extractant according to claim 3, characterized in that: The pH adjuster is hydrochloric acid.

7. The method for separating gold from electroplating wastewater using a composite extractant according to claim 3, characterized in that: The gold-containing wastewater is one or more of mineral resource solution, catalyst waste liquid, and metallurgical waste liquid.

8. The method for separating gold from electroplating wastewater using a composite extractant according to claim 7, characterized in that: The gold is in the form of AuCl4 - Form exists.

9. The method for separating gold from electroplating wastewater using a composite extractant according to claim 3, characterized in that: The volume ratio of the gold-containing wastewater to the extractant diluent is 1:(1-2).

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