Method for recovering Cu or EDTA ligand in Cu (II)-EDTA wastewater through one-step complex breaking

Abstract

The invention provides a method for recovering Cu or EDTA ligand in Cu (II)-EDTA wastewater by one-step complex breaking, which comprises the following steps: adding manganese powder wrapped by a proton exchange membrane into Cu (II)-EDTA-containing wastewater for ultrasonic reaction, keeping the wastewater free of dissolved oxygen and the pH value below 3 in the reaction process, and obtaining Cu0 on the surface of the proton exchange membrane after the reaction is completed. According to the method provided by the invention, the Cu and the EDTA can be recycled respectively, the reaction rate is high, the treatment process is simple, the copper and the EDTA are converted into resources which can be directly recycled, and the time and the economic cost are saved.

Description

Technical Field

[0001] This invention belongs to the field of environmental remediation of industrial heavy metal wastewater, and specifically relates to a method for one-step complex breaking and recovery of Cu or EDTA ligands in Cu(II)-EDTA wastewater. Background Technology

[0002] With the rapid development of the electronics manufacturing and precision machining industries, electroless copper plating has been widely used due to its excellent coating uniformity. This process achieves metal deposition by forming a stable complex between EDTA and copper ions. However, the Cu(II)-EDTA complex wastewater generated during the production process has strong chemical stability and biotoxicity. Traditional treatment technologies such as Fenton oxidation and chemical precipitation suffer from technical bottlenecks such as low degradation efficiency, long treatment cycles, and excessive heavy metal residues. This results in the disorderly discharge of nearly one million tons of copper-containing wastewater annually, posing a serious threat to the aquatic ecological environment and human health, and causing a large loss of heavy metal resources. Existing technologies mostly focus on pollutant removal and lack resource recovery designs for copper and EDTA, which wastes resources and exacerbates the environmental pressure of raw material mining.

[0003] The prior art CN 118929883 A discloses a method for treating Cu(II)-EDTA wastewater by ball milling zero-valent manganese. This method improves the surface defects of zero-valent manganese through ball milling, thus increasing removal efficiency compared to unmilled zero-valent manganese. However, after removing Cu(II)-EDTA, the reacted manganese needs to be dissolved in acid to achieve the separation of Cu and Mn. Subsequent Cu recovery... 0 Furthermore, the dissolved Cu ions need to be further reduced, and the steps for recovering Cu or regenerating manganese are very complicated. Summary of the Invention

[0004] To address the aforementioned problems, this invention provides a one-step method for breaking down complexes and recovering Cu and EDTA ligands from Cu(II)-EDTA wastewater. This method borrows from the "tea bag" approach, using manganese powder encapsulated in a proton exchange membrane to be added to the wastewater. This achieves decomplexing of Cu(II)-EDTA and complete recovery of all components under anaerobic conditions. The reaction can be rapidly completed at room temperature and pressure. After the reaction is complete, Cu can be easily recovered. 0 By combining copper and EDTA, a highly efficient and sustainable wastewater treatment solution can be provided, transforming copper into a directly reusable resource.

[0005] To achieve the above objectives, the present invention adopts the following technical solution: A method for one-step complex breaking and recovery of Cu or EDTA ligands from Cu(II)-EDTA wastewater includes: Manganese powder coated with a proton exchange membrane was added to wastewater containing Cu(II)-EDTA and subjected to ultrasonic reaction. During the reaction, the wastewater was kept free of dissolved oxygen and the pH was below 3. After the reaction was completed, Cu was obtained on the surface of the proton exchange membrane. 0 .

[0006] Preferably, the method further includes filtering the solution after the reaction to obtain EDTA ligands in the filter cake. Since the solution is kept free of dissolved oxygen and the pH is below 3 during the reaction, EDTA will precipitate as a solid in the reaction system, which can be directly recovered by filtration after the reaction.

[0007] Preferably, the amount of manganese powder used is 0.5~1.5 g / L, more preferably 1 g / L, that is, 1 g of manganese powder is added per liter of wastewater according to the amount of wastewater used.

[0008] Preferably, the thickness of the proton exchange membrane is 5-20 μm, more preferably 8 μm.

[0009] Preferably, the Cu(II)-EDTA in the wastewater is 500 mg / L.

[0010] Preferably, the reaction temperature is 25 °C.

[0011] Preferably, the initial pH of the reaction is 3.

[0012] Preferably, the method for maintaining the pH of the wastewater to below 3 is to adjust it by adding dilute sulfuric acid.

[0013] Preferably, the ultrasonic power is 150~200 W and the frequency is 35~45 kHz, more preferably 180 W and 40 kHz.

[0014] Preferably, the reaction time is 270 minutes.

[0015] Preferably, the method for maintaining the wastewater free of dissolved oxygen is as follows: continuously introducing an inert gas into the wastewater for more than 30 minutes, then carrying out the reaction, and continuing to introduce the inert gas during the reaction.

[0016] Preferably, the inert gas is nitrogen.

[0017] The beneficial effects of this invention are as follows: (1) The method of the present invention can recover Cu while removing Cu(II)-EDTA. 0 No additional recovery reaction is required, and the reaction conditions are minimally restricted; it can be carried out at room temperature and pressure.

[0018] (2) The method of the present invention is simple, practical, mild, easy to operate, low in equipment requirements, and conducive to large-scale promotion, with significant economic and environmental benefits. Attached Figure Description

[0019] Figure 1 This is a diagram showing the effect of Cu(Ⅱ)-EDTA removal in Example 1.

[0020] Figure 2 This is a diagram showing the effect of EDTA removal in Example 3.

[0021] Figure 3 These are SEM-mapping images after the reaction in Example 3. Figure a shows the contact surface with manganese powder, and Figure b shows the contact surface with contaminants.

[0022] Figure 4 This is the XRD of the copper recovered in Example 3.

[0023] Figure 5 This is the infrared spectrum of the EDTA recovered in Example 3.

[0024] Figure 6 The graph shows the removal effect of Cu(Ⅱ)-EDTA and EDTA in Comparative Example 1.

[0025] Figure 7 This is the infrared spectrum of the filter cake recovered in Comparative Example 2. Detailed Implementation

[0026] The method of the present invention will be further described below with reference to specific embodiments. The following are only specific embodiments of the method of the present invention, but the protection scope of the method of the present invention is not limited thereto.

[0027] The main raw materials involved in the following examples, such as manganese powder (ZVMn), are all from Maclean (Shanghai, China). All reagents are of analytical grade, and the manganese powder has a purity of 99% and a particle size of 200 mesh.

[0028] Example 1 Manganese powder was weighed according to the dosage of 1.5g per liter of wastewater and wrapped in a 5 μm thick proton exchange membrane to form a "tea bag" shape. A 500 mg / L Cu(II)-EDTA solution was added to a 100 mL beaker, and the initial pH of the reaction was adjusted to 3 using dilute sulfuric acid. Inert gas was bubbled into the solution for at least 30 minutes. Then, the proton exchange membrane-wrapped manganese powder was added to the Cu(II)-EDTA solution, and ultrasonic treatment was performed at a power of 150 W, a frequency of 45 kHz, and a temperature of 25 ℃. Dilute sulfuric acid was used to adjust the pH to ≤ 3 throughout the process. Samples were taken at regular intervals to determine the residual amounts of Cu(II)-EDTA and EDTA in the system, and aeration was maintained until the end of the experiment. The experimental results are as follows: Figure 1 Cu(Ⅱ)-EDTA was removed within 270 minutes.

[0029] Example 2 Manganese powder was weighed at a dosage of 0.5 g per liter of wastewater and wrapped in a 20 μm thick proton exchange membrane to form a "tea bag" shape. A 500 mg / L Cu(II)-EDTA solution was added to a 100 mL beaker, and the initial pH was adjusted to 3 using dilute sulfuric acid. Inert gas was then bubbled into the solution for at least 30 minutes. Subsequently, the proton exchange membrane-wrapped manganese powder was added to the Cu(II)-EDTA solution, and ultrasonic treatment was performed at a power of 200 W, a frequency of 35 kHz, and a temperature of 25 ℃. The pH was maintained at ≤ 3 using dilute sulfuric acid throughout the process. Samples were taken at regular intervals to determine the residual amounts of Cu(II)-EDTA and EDTA in the system, and aeration was maintained until the end of the experiment. The results showed that Cu(II)-EDTA was removed within 270 minutes.

[0030] Example 3 Manganese powder was weighed according to the dosage of 1g per liter of wastewater and wrapped in an 8 μm thick proton exchange membrane to form a "tea bag" shape. A 500 mg / L Cu(II)-EDTA solution was added to a 100 mL beaker, and the initial pH was adjusted to 3 using dilute sulfuric acid. Inert gas was bubbled into the solution for at least 30 minutes. Then, the proton exchange membrane-wrapped manganese powder was added to the Cu(II)-EDTA solution, and ultrasonic treatment was performed at a power of 180 W, a frequency of 40 kHz, and a temperature of 25 ℃. Dilute sulfuric acid was used to adjust the pH to ≤ 3 throughout the process. Samples were taken at regular intervals to determine the residual amount of EDTA in the system, and aeration was maintained until the end of the experiment. The experimental results are as follows: Figure 2 EDTA was removed within 270 minutes.

[0031] After the reaction, the manganese powder encapsulated in the proton exchange membrane was removed, and the manganese powder and proton exchange membrane were separated. The surface of the proton exchange membrane was rinsed multiple times with deionized water, and after vacuum drying for 6 hours, the surface recoveries were peeled off to obtain Cu. 0 and the obtained Cu 0 SEM and EXR characterization were performed, and the results are as follows: Figure 3 , 4 As shown. By Figure 3 It can be seen that Cu has been enriched on the film surface.

[0032] The remaining solution after removing the manganese powder encapsulated in the proton exchange membrane was filtered to obtain a filter cake, which was then washed and dried to obtain EDTA.

[0033] Experimental results are as follows Figure 3 As shown, the copper signal was significantly enhanced after the reaction, achieving copper recovery. Figure 5 As shown, the characteristic peaks of the recovered EDTA are highly consistent with those of industrial-grade EDTA, indicating that the recovered EDTA has high purity.

[0034] Comparative Example 1 Manganese powder was weighed according to the dosage of 1g per liter of wastewater and wrapped in a proton exchange membrane with a thickness of 8 μm to form a "tea bag" shape. A 500 mg / L Cu(II)-EDTA solution was added to a 100 mL beaker, and an inert gas was bubbled into the solution for at least 30 minutes. Then, the proton exchange membrane-wrapped manganese powder was added to the Cu(II)-EDTA solution, and the mixture was sonicated at a power of 180 W, a frequency of 40 kHz, and a temperature of 25 ℃. Samples were taken at regular intervals to determine the residual amounts of Cu(II)-EDTA and EDTA in the system, and aeration was maintained until the end of the experiment. The experimental results are as follows: Figure 6 Cu(II)-EDTA was removed within 270 minutes, but EDTA was not recovered, increasing the complexity of the process. A comparison of Comparative Example 1 and Examples 1 and 2 shows that EDTA can only be recovered if the pH is maintained below 3 throughout the entire process. If the pH is only adjusted to 3 before the reaction begins, the pH will gradually increase during the reaction, ultimately preventing EDTA recovery.

[0035] Comparative Example 2 Add 500 mg / L Cu(II)-EDTA solution to a 100 mL beaker. Adjust the initial pH of the reaction to 3 using dilute sulfuric acid. Purge the solution with inert gas for at least 30 minutes. Then, directly add ball-milled zero-valent manganese powder to the Cu(II)-EDTA solution, followed by ultrasonic treatment at 180 W, 40 kHz, and 25 ℃. Maintain pH ≤ 3 with dilute sulfuric acid throughout the process, and continue purging until the experiment is complete. Filter the resulting solution to obtain a filter cake, wash and dry it, and then test its purity. The experimental results are as follows: Figure 7 The filter cake infrared test results were incompatible with industrial-grade EDTA, indicating that this comparative ratio cannot achieve the separation and recovery of EDTA.

[0036] The embodiments described above are merely illustrative of several implementations of the present invention, and while the descriptions are specific and detailed, they should not be construed as limiting the scope of the present invention. It should be noted that those skilled in the art can make various modifications and improvements without departing from the concept of the present invention, and these modifications and improvements all fall within the scope of protection of the present invention. Therefore, the scope of protection of this patent should be determined by the appended claims.

Claims

1. A method for one-step complex breaking and recovery of Cu or EDTA ligands from Cu(II)-EDTA wastewater, characterized in that, include: Manganese powder coated with a proton exchange membrane was added to wastewater containing Cu(II)-EDTA and subjected to ultrasonic reaction. During the reaction, the wastewater was kept free of dissolved oxygen and the pH was below 3. After the reaction was completed, Cu was obtained on the surface of the proton exchange membrane. 0 .

2. The method according to claim 1, characterized in that, The method further includes filtering the reacted solution to obtain EDTA ligands in the filter cake.

3. The method according to claim 1, characterized in that, The amount of manganese powder used is 0.5~1.5 g / L, more preferably 1 g / L.

4. The method according to claim 1, characterized in that, The thickness of the proton exchange membrane is 5~20 μm, more preferably 8 μm.

5. The method according to claim 1, characterized in that, The Cu(II)-EDTA in the wastewater was 500 mg / L.

6. The method according to claim 1, characterized in that, The reaction was carried out at a temperature of 25 °C.

7. The method according to claim 1, characterized in that, The method to maintain the pH of the wastewater below 3 is to add dilute sulfuric acid for adjustment.

8. The method according to claim 1, characterized in that, The ultrasonic power is 150~200 W and the frequency is 35~45 kHz, more preferably 180 W and 40 kHz.

9. The method according to claim 1, characterized in that, The reaction time was 270 minutes.

10. The method according to claim 1, characterized in that, The method for maintaining the wastewater free of dissolved oxygen is as follows: continuously introduce inert gas into the wastewater for more than 30 minutes, then carry out the reaction, and continue to introduce inert gas during the reaction process.

Images