Composite extractant and method for separating gold from electroplating wastewater

Abstract

The present application provides a composite extractant and a method for separating gold from electroplating wastewater, belonging to the field of wastewater purification. The composite extractant includes an extraction main agent and an extraction main agent stabilizer. The extraction main agent is a diallyl disulfide compound, and the extraction main agent stabilizer is dithiothreitol. The extraction main agent can form a stable complex with gold ions and enter the organic phase. Its non-linear spatial structure can achieve selective coordination with gold ions, avoiding coordination reactions with other impurity metal ions. The sulfhydryl groups in the molecular structure of dithiothreitol have reducibility, which can prevent the residual oxidant or dissolved oxygen in the solution from oxidizing the extraction main agent and maintain the non-linear polysulfur structure of the extraction main agent. By regulating the multi-component of the composite extractant, the present application ensures the heterogeneous interface-coordination reaction between the active sites in the molecular structure of the extractant and gold ions in the inorganic phase, realizes the efficient selective chelation of target metals, and achieves the purpose of separating and enriching gold ions in gold-containing electroplating waste liquid.

Description

Technical Field

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

[0002] At present, the treatment methods for heavy metal gold in industrial wastewater mainly include: chemical precipitation method, redox method, solvent extraction method, adsorption method, membrane separation method, ion exchange method, etc. Among them, the solution extraction method can achieve the separation and enrichment of target metals. 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 process is the screening of extractant types. On the basis of achieving efficient extraction of target metal ions, it is necessary to take into account the selective extraction of target metal ions and avoid the co-extraction of impurity metals.

[0003] In the field of treating gold-containing electroplating wastewater, the extractants currently used have certain limitations, mainly manifested as easy co-extraction of impurity metals, poor selectivity, and difficulty in achieving selective extraction of gold in 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 in the background art, the present application provides a composite extractant and a method for separating gold from electroplating wastewater, aiming to solve the technical problem of poor selectivity of existing extractants when treating gold-containing electroplating wastewater.

[0006] In the first aspect, the present application provides a composite extractant, which includes an extraction main agent and an extraction main agent stabilizer. The extraction main agent is a diallyl disulfide 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 disulfide compound is or .

[0008] In the second aspect, the embodiments of the present application provide a method for separating gold from electroplating wastewater using the composite extractant described in the first aspect. The extraction is carried out using the composite extractant, and the method includes the following steps:

[0009] Mix the extraction main agent and the extraction main agent stabilizer, add a diluent and dissolve it by ultrasonic treatment to obtain an extractant diluent;

[0010] Add a pH regulator to the gold-containing wastewater to adjust the pH value of the solution to 1-6. Subsequently, add the diluent of the extractant to achieve selective extraction of gold in the solution.

[0011] As a further improvement of the present application, the diluent is sulfonated kerosene.

[0012] As a further improvement of the present application, the mass ratio of the total mass of the main extractant and the main extractant stabilizer to the mass of the diluent is 1:(9-29).

[0013] As a further improvement of the present application, the pH regulator is hydrochloric acid.

[0014] As a further improvement of the present application, the gold-containing wastewater is one or more of mineral resource solutions, catalyst waste liquids, and metallurgical waste liquids.

[0015] As a further improvement of the present application, the gold exists in the solution in the form of AuCl4 - -

[0016] As a further improvement of the present application, the volume ratio of the gold-containing wastewater to the diluent of the extractant is 1:(1-2).

[0017] The beneficial effects of the present application are as follows:

[0018] The present application provides a composite extractant and a method for separating gold from electroplating wastewater. The composite extractant includes a main extractant and a main extractant stabilizer. The main extractant is diallyl disulfide compound, and the main extractant stabilizer is dithiothreitol. The main extractant can form a stable complex with gold ions and enter the organic phase. In addition, the non-linear spatial structure of diallyl disulfide compound can achieve selective coordination with gold ions, avoiding coordination reactions with other impurity metal ions. The sulfhydryl group (-SH) in the molecular structure of dithiothreitol has reducibility, which can prevent the residual oxidant or dissolved oxygen in the solution from oxidizing the main extractant and maintaining the non-linear polysulfur structure of the main extractant. By regulating the multi-component of the composite extractant, it ensures the heterogeneous interface-coordination reaction between the activation sites in the molecular structure of the extractant and gold ions in the inorganic phase, realizes the efficient selective chelation of the target metal, and achieves the purpose of separating and enriching gold ions in the gold-containing electroplating waste liquid.

[0019] 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 specifically illustrates the specific embodiments of the present application. Specific Embodiments

[0020] The embodiments of the technical solution of the present application will be described in detail below. 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.

[0021] 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 are intended to cover non-exclusive inclusion.

[0022] In the description of the embodiments of the present 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 the present application, the meaning of "a plurality" is more than two, unless otherwise specifically defined.

[0023] 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 the present application. The phrase appears in various places 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.

[0024] In the description of the embodiments of the present application, the term "a plurality" 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).

[0025] At present, the extractants used in the field of treating gold-containing electroplating wastewater have certain limitations: during the extraction process, impurity metals are easily co-extracted, the selectivity for target metals is poor, and it is difficult to achieve selective extraction of gold in gold-containing electroplating wastewater.

[0026] In order to solve the technical problem that it is difficult for existing extractants to achieve selective extraction of gold in gold-containing electroplating wastewater, the present application provides a composite extractant and a method for separating gold from electroplating wastewater. Among them, the composite extractant includes an extraction main agent and an extraction main agent stabilizer. The extraction main agent is a diallyl disulfide compound, and the extraction main agent stabilizer is dithiothreitol. By regulating the multiple components of the composite extractant, the heterogeneous interface-coordination reaction between the activation sites in the molecular structure of the extractant and gold ions in the inorganic phase is ensured, and efficient selective chelation of target metals is achieved, so as to achieve the purpose of separating and enriching gold ions in gold-containing electroplating waste liquid.

[0027] In a first aspect, an embodiment of the present application provides a composite extractant, which includes an extraction main agent and an extraction main agent stabilizer. The extraction main agent is a diallyl disulfide 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.

[0028] In the technical solution of the embodiment of the present application, according to Pearson's hard-soft acid-base theory, sulfur in the polysulfide bond of the disulfide compound belongs to an electron donor (soft base), while the gold (I) ion, as an electron acceptor, belongs to a soft acid. The electron cloud of the gold (III) ion has a large deformability and the ability to accept electrons, which is between soft acid and hard acid. According to the hard-soft acid-base theory, the extraction main agent of the diallyl disulfide compound can form a stable complex with the gold ion and enter the organic phase. In addition, the non-linear spatial structure of the diallyl disulfide compound can achieve selective coordination with the gold ion, avoiding the coordination reaction with other impurity metal ions.

[0029] The extraction main agent stabilizer in the composite extractant is dithiothreitol, and its molecular structural formula is . The mercapto group (-SH) in the molecular structure of dithiothreitol has reducibility, which can prevent the residual oxidant or dissolved oxygen in the solution from oxidizing the extraction main agent and maintain the non-linear polysulfide structure of the extraction main agent.

[0030] By adjusting the ratio of the extraction main agent to the extraction main agent stabilizer, it can be ensured that the composite extractant has high extraction ability and stability when treating gold-containing wastewater. An appropriate ratio of the extraction main agent to the extraction main agent 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. An excessively high ratio of the extraction main agent stabilizer may reduce the capacity of the extractant, while an excessively low ratio of the extraction main agent stabilizer may not be sufficient to protect the extraction main agent, affecting its stability and service life, and further affecting the extraction efficiency. By optimizing the ratio, the dosage of the extraction main agent can be reduced and the treatment cost can be lowered.

[0031] Further, in some embodiments, the diallyl disulfide compound is or .

[0032] In the technical solution of the embodiment of the present application, the diallyl disulfide compound is (diallyl disulfide) or (diallyl trisulfide). Due to their special molecular structures, these two compounds can improve the selective extraction of gold, thereby reducing the co-extraction of impurity metals during the treatment of gold-containing electroplating wastewater and improving the gold recovery efficiency.

[0033] Second aspect, an embodiment of the present application provides a method for separating gold from electroplating wastewater using a composite extractant. The composite extractant described in the first aspect is used for extraction, and the method includes the following steps:

[0034] S1. Mix the extraction main agent and the extraction main agent stabilizer, add a diluent and dissolve them by ultrasonic treatment to obtain an extractant diluent;

[0035] S2. Add a pH regulator to the gold-containing wastewater to adjust the pH value of the solution to 1-6. Then, add the extractant diluent to achieve selective extraction of gold in the solution.

[0036] In the technical solution of the embodiment of the present application, by using diallyl disulfide compound as the extraction main agent and mixing it with the extraction main 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 extraction main agent stabilizer helps to protect the extraction main agent from oxidation or hydrolysis, thereby prolonging the service life of the extractant. By adjusting the pH value of the solution to acidic, it can ensure that the extraction process is carried out under optimal conditions. Specifically, add the extractant diluent to the gold-containing wastewater, oscillate in a water bath at 25-28°C for 5-10 minutes to selectively extract gold in the solution. After the extraction is completed, separate the organic phase, detect the concentration of gold in the inorganic liquid phase solution and calculate the extraction rate. This method can reduce the use of harmful chemicals, improve the recovery rate of gold, and reduce resource waste. Through effective gold extraction and recovery, the recovery value of gold in electroplating wastewater can be increased, and the treatment cost can be reduced.

[0037] Further, in some embodiments, the diluent is sulfonated kerosene.

[0038] In the technical solution of the embodiment of the present application, sulfonated kerosene has good compatibility with the composite extractant, can effectively dilute and disperse the extraction main agent, and form a stable extraction system.

[0039] Further, in some embodiments, the mass ratio of the total mass of the extraction main agent and the extraction main agent stabilizer to the mass of the diluent is 1:(9-29).

[0040] In the technical solution of the embodiment of the present application, an appropriate amount of diluent can ensure that the extraction main 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.

[0041] Further, in some embodiments, the pH regulator is hydrochloric acid.

[0042] 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, promoting the reaction between gold ions and the extractant. Under acidic conditions, the activity of other metal ions may decrease, thereby reducing the interaction between other metals and the extractant and improving the selective extraction of gold.

[0043] Further, in some embodiments, the gold-containing wastewater is one or more of a mineral resource solution, a catalyst waste liquid, and a metallurgical waste liquid.

[0044] In the technical solution of the embodiment of the present application, the composite extractant can meet the treatment requirements of gold-containing wastewater from different sources and has good selectivity.

[0045] Further, in some embodiments, gold exists in the solution in the form of AuCl4 - form.

[0046] In the technical solution of the embodiment of the present application, under acidic conditions, gold can exist in the form of AuCl4 - (tetrachloroaurate), and this form is more likely to form a stable complex with the diallyl disulfide compound in the composite extractant, improving the selective extraction of gold.

[0047] Further, in some embodiments, the volume ratio of the gold-containing wastewater to the extractant diluent is 1:(1 - 2).

[0048] In the technical solution of the embodiment of the present application, an appropriate volume ratio can ensure sufficient contact between the extractant and the gold ions in the gold-containing wastewater, thereby improving the extraction efficiency of gold.

[0049] The following are 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 embodiments where specific technologies or conditions are not indicated, the technologies or conditions described in the literature in this field or according to the product specifications are followed. For reagents or instruments whose manufacturers are not indicated, they are all conventional products that can be obtained through commercial purchase.

[0050] Example 1

[0051] This embodiment provides a composite extractant, which includes an extraction main agent and an extraction main agent stabilizer. The extraction main agent is diallyl disulfide, and the extraction main agent stabilizer is dithiothreitol. The composite extractant is used to separate gold from electroplating wastewater. The specific steps are as follows:

[0052] S1. Mix the extraction main agent and the extraction main agent stabilizer according to a mass ratio of 9:1, and mix the total mass of the extraction main agent and the extraction main agent stabilizer with sulfonated kerosene according to a mass ratio of 1:9, and ultrasonically dissolve to obtain an extractant diluent;

[0053] 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%.

[0054] Examples 2-6 and Comparative Example 1

[0055] 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.

[0056]

[0057] 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%.

[0058] Comparative Example 2

[0059] 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.

[0060] Comparative Examples 3-8

[0061] 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.

[0062]

[0063] As can be seen from Table 2, the main extractant stabilizer in the composite extractant plays an important role. The sulfhydryl group (-SH) in the molecular structure of the main extractant stabilizer (dithiothreitol) has reducibility, which can prevent the residual oxidant or dissolved oxygen in the solution from oxidizing the main extractant and maintain its chemical stability. When the types of the composite extractant system are complete and the dosage ratio is reasonable, through the mutual cooperation of the agents in each functional unit, a synergistic effect is achieved to realize the efficient extraction of gold.

[0064] Examples 7-14

[0065] Examples 7-14 respectively provide a method for separating gold from electroplating wastewater by using a composite extractant. The composite extractant provided in Example 1 is used to extract and separate gold from a solution of multiple coexisting ions respectively. The specific operation steps are as follows:

[0066] Prepare a series of blended solutions containing gold, tungsten, molybdenum, rhenium, and copper with different concentration ratios. Take 50 ml of the diluent of the extractant provided in Example 1 and add it to 50 mL of the blended solution respectively. After shaking at 25 °C for 5 min, take the inorganic liquid phase and use ICP-OES to detect the concentration of each metal ion in the solution, and then calculate the extraction rate. Among them, the detection error of ICP-OES is ±2%. The extraction effect is shown in Table 3.

[0067]

[0068] As can be seen from Table 3, the composite extractant has a selective extraction effect on gold and will not extract metal ions such as tungsten, molybdenum, rhenium, and copper, especially copper ions, ensuring the selective separation and enrichment of gold in the composite extraction solution. Other types of polysulfide do not have the above advantages. The main reasons are as follows: First, the unique non-linear molecular spatial structure of the main extractant achieves 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.

[0069] It should be noted that this application is not limited to the above embodiments. The above embodiments are only examples. Embodiments with the same structure and the same function and effect as the technical idea within the technical scope of this application are included in the technical scope of this application. In addition, within the scope of not departing from the main idea of this application, various deformations that those skilled in the art can think of for the embodiments, and other ways constructed by combining some components of the embodiments are also included in the scope of this application.

Claims

1. A composite extractant, comprising an extracting agent and an extracting agent stabilizer, characterized in that: The main extracting agent is a diallyl sulfide compound, and the main extracting agent stabilizer is dithiothreitol; the mass ratio of the main extracting agent to the main extracting agent stabilizer is (9-99):1; the diallyl sulfide compound is or .

2. A method for separating gold from electroplating wastewater using a composite extractant, using the composite extractant according to claim 1 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; Add a pH adjuster to the gold-containing wastewater to adjust the pH value of the solution to 1-6, wherein the pH adjuster is hydrochloric acid; gold is in the solution as AuCl4 - There is a form; thereafter, the extractant diluent is added to achieve selective extraction of gold in the solution.

3. The method for separating gold from electroplating wastewater using a composite extractant according to claim 2, characterized in that: The diluent is sulfonated kerosene.

4. The method for separating gold from electroplating wastewater using a composite extractant according to claim 3, 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).

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

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