A 3D-printed zero-valent iron doped electrode for removing copper ions in wastewater and a preparation method and application thereof

Abstract

The application discloses a 3D printing zero-valent iron doped electrode for removing copper ions in wastewater and a preparation method and application thereof. The method comprises the following steps: mixing zero-valent iron powder, nickel oxide powder, carbon nanotubes and soluble organic carbon according to a proportion, adding pure water to carry out a reaction, carrying out positive and negative rotation alternating ball milling, drying, and screening to obtain mixed spherical zero-valent iron powder, using a metal laser 3D printing equipment to carry out 3D printing according to a 3D structure model, cutting and cleaning after printing, and obtaining the 3D printing zero-valent iron doped electrode. The 3D printing zero-valent iron doped electrode prepared by the application has the advantages of small volume, strong operability and easy recovery. The added soluble organic carbon and carbon nanotubes respectively strengthen the oxidation resistance of iron and nickel, have more contact points with copper ions, have stronger adsorption capacity for copper ions, the 3D printing three-dimensional structure enhances the water mass transfer capacity of the electrode and increases the specific surface area of the electrode, and the wastewater containing 3g / L copper ions can be removed in only two hours.

Description

Technical Field

[0001] This invention relates to the technical field of water pollution control and remediation, and more specifically, to a 3D-printed zero-valent iron-doped electrode for removing copper ions from wastewater, its preparation method, and its application. Background Technology

[0002] Existing electrodeposition processes can recover valuable metals while treating wastewater containing heavy metal ions. However, this process requires a high concentration of heavy metal ions (generally, the concentration of metal ions should be greater than 10 g / L). As the deposition process proceeds, the concentration of heavy metal ions gradually decreases, and the wastewater treatment effect also declines. Furthermore, it requires a large current density, resulting in high operating and financial costs.

[0003] SLM (Surface-Modulated Laser Melting) is widely used for fabricating macroscopic metallic structures. Using a high-power laser beam, fine metal powders are selectively fused and consolidated layer by layer according to predefined computer-aided design data to create macroscopic metallic structures with complex and precise geometries. However, in the SLM process, the complete melting, solidification, and ultrafast cooling processes can affect the characteristics of the metal macrostructure (e.g., surface composition and surface roughness), which play a crucial role in determining the reactivity of the macrostructure of metal catalysts. Catalytic materials prepared by traditional methods such as hydrothermal processes are prone to deactivation during use due to the shedding of active materials. In contrast, 3D-printed electrodes can provide more active sites and efficient mass transfer rates for electrochemical reactions, exhibiting superior performance in degrading various recalcitrant substances. Summary of the Invention

[0004] The purpose of this invention is to provide a 3D-printed zero-valent iron-doped electrode for removing copper ions from wastewater, its preparation method, and its application.

[0005] According to one aspect of the present invention, a method for preparing a 3D-printed zero-valent iron-doped electrode for removing copper ions from wastewater is provided, comprising the following steps: S1. Place zero-valent iron powder, nickel oxide powder, carbon nanotubes and soluble organic carbon into a container according to a certain mass ratio, add pure water to react, let stand for 12 hours, when the container shows stratification and the upper layer is clear, pour out the upper liquid and keep the lower aggregate. S2. Add the above aggregate into a planetary ball mill jar pre-filled with ball milling steel balls and ball mill in alternating forward and reverse directions to obtain uniformly mixed spherical iron powder; S3. Place the spherical iron powder in an oven to dry, and then mechanically sieve it to obtain mixed spherical zero-valent iron powder; S4. Select a metal laser 3D printing equipment, install the metal printing plate of the printing equipment and level it so that the four planes of the printing plate are parallel. Install the powder spreading scraper, make it parallel to the printing plate and lower it to the position where it just touches the printing plate. S5. Pour the mixed spherical zero-valent iron powder into the powder tank of the 3D printing equipment. Turn on the protective gas and cooling water tank in sequence, and supply argon gas to reduce the dissolved oxygen content in the printer chamber to 250 ppm and the water tank temperature to 20℃. Open and download the pre-modeled internal porous 3D structure model, and use alternating scanning with equal intervals of 75° in the X and Y directions. The scanning speed range is 800~1000 mm / s, the laser power range is 120~140 W, the scanning interval is 0.08~0.102mm, the powder layer thickness is 0.05 mm, and the laser peak value is set to 100. Printing can only be started after the laser is turned on. S6. After 3D printing is completed, allow it to cool naturally, cut it, soak it in anhydrous ethanol, and ultrasonically clean it to remove surface oil and obtain a 3D printed zero-valent iron-doped electrode.

[0006] In some embodiments, the mass ratio of zero-valent iron powder, nickel oxide powder, carbon nanotubes, and soluble organic carbon in step S1 is 91:5:2:2.

[0007] In some embodiments, the mass ratio of the milling steel balls to the aggregate in step S2 is 4:1, and the duration of the alternating forward and reverse milling is 2 hours.

[0008] In some embodiments, the drying temperature in step S3 is 60-65°C, and the drying time is 3-5 hours.

[0009] In some implementations, the mesh size of the sieve used for mechanical sieving in step S3 is 200 mesh.

[0010] In some embodiments, the protective gas in step S4 is a mixture of 98% argon and 2% hydrogen.

[0011] According to another aspect of the present invention, a 3D-printed zero-valent iron-doped electrode is provided, which is prepared by a method for preparing a 3D-printed zero-valent iron-doped electrode for removing copper ions from wastewater.

[0012] According to another aspect of the present invention, a method for preparing a 3D-printed zero-valent iron-doped electrode for removing copper ions from wastewater is provided, and the application of the prepared 3D-printed zero-valent iron-doped electrode in removing copper ions from wastewater is described.

[0013] According to a fourth aspect of the present invention, a method for removing copper ions from wastewater is provided, comprising the following steps: A 3D-printed zero-valent iron-doped electrode, prepared by a method for preparing a 3D-printed zero-valent iron-doped electrode for removing copper ions from wastewater, is used to remove copper ions from the wastewater. (1) The 3D printed zero-valent iron doped electrode was immersed in 1% hydrochloric acid solution and ultrasonically treated for 5 minutes to remove the oxide layer on the surface of the 3D printed zero-valent iron doped electrode. (2) The 3D-printed zero-valent iron-doped electrode with the oxide layer removed was placed in an electrolytic cell containing copper-containing simulated wastewater, and the current density was 30 mA / cm². 2 Under the condition of an initial pH of 5, electrodeposition was performed. 1 mL of the reaction solution was taken at different reaction times t, and the concentration of copper ions in the taken reaction solution was detected using an ICP instrument.

[0014] In some embodiments, the copper-containing simulated wastewater is simulated wastewater containing 3 g / L of copper ions and 100 mM of anhydrous sodium sulfate.

[0015] The beneficial effects of the present invention are: (1) The 3D printed zero-valent iron doped electrode prepared by the present invention is small in size, highly operable, and easy to recycle. The added soluble organic carbon and carbon nanotubes enhance the antioxidant capacity of iron and nickel respectively. The doping of multiple materials gives it more contact points with copper ions, and its adsorption capacity for copper ions is stronger. The three-dimensional structure designed by 3D printing enhances the water mass transfer capacity of the electrode and increases its specific surface area. It can remove wastewater containing 3g / L copper ions in just two hours. (2) The 3D printed zero-valent iron doped electrode prepared by the present invention has low operating cost, low current density, short operating time, high mechanical strength and good cycle performance; (3) The 3D printed zero-valent iron doped electrode prepared by the present invention has less iron and nickel ion leakage, which avoids secondary pollution of water bodies. It has a good treatment effect on low-concentration copper wastewater and strong environmental adaptability. It can be used to remove copper ions in different water bodies. The material operates stably, occupies a small area, and is easy to operate. Attached Figure Description

[0016] Figure 1 This is a comparison chart showing the removal effect of the 3D-printed zero-valent iron-doped electrode of Embodiment 3 of the present invention on wastewater with different concentrations of copper ions.

[0017] Figure 2 A comparison graph showing the copper removal efficiency of nickel oxide added to the 3D-printed zero-valent iron-doped electrode in Example 4 of the present invention.

[0018] Figure 3 This is a comparison graph showing the effect of different nickel oxide addition amounts on the copper removal efficiency of 3D-printed zero-valent iron-doped electrodes in Example 5 of the present invention.

[0019] Figure 4 This is a comparison graph showing the effect of different amounts of carbon nanotubes added on the copper removal efficiency of the 3D-printed zero-valent iron-doped electrode in Example 6 of the present invention.

[0020] Figure 5 This is a comparison graph showing the effect of different amounts of soluble organic carbon added on the copper removal efficiency of the 3D-printed zero-valent iron-doped electrode in Example 7 of the present invention. Detailed Implementation

[0021] The present invention is further described in detail through specific implementation examples. It should be understood that these embodiments are for illustrative purposes only and are not intended to limit the scope of protection of the present invention. After reading this invention, any modifications of the present invention in various equivalent forms by those skilled in the art fall within the scope defined by the appended claims. Unless otherwise specified, all raw materials and reagents of the present invention are commercially available.

[0022] Example 1

[0023] A method for preparing a 3D-printed zero-valent iron-doped electrode for removing copper ions from wastewater includes the following steps: S1. Weigh zero-valent iron powder, nickel oxide powder, carbon nanotubes and soluble organic carbon in a mass ratio of 91:5:2:2 and put them into a beaker. Add pure water until the liquid level is 5-6 cm above the mixed powder. Stir to react with the pure water. Let stand for 12 hours. When the beaker shows stratification and the upper layer is clear, pour out the upper liquid and keep the lower aggregate. S2. Add a certain amount of ethanol to the planetary ball mill jar, add the above aggregate to the planetary ball mill jar pre-filled with grinding steel balls, and perform alternating forward and reverse ball milling for 2 hours to obtain uniformly mixed spherical iron powder. The mass ratio of grinding steel balls to aggregate is 4:1. S3. Place the spherical iron powder in an oven and dry it at 60~65℃ for 3~5 hours, then mechanically sieve it through a 200-mesh sieve for 10 minutes to obtain mixed spherical zero-valent iron powder; S4. Select a metal laser 3D printing equipment, install the metal printing plate of the printing equipment and level it so that the four planes of the printing plate are parallel. Install the powder spreading scraper, make it parallel to the printing plate and lower it to the position where it just touches the printing plate. S5. Pour the mixed spherical zero-valent iron powder into the powder tank of the 3D printing equipment. Turn on the protective gas (98% argon, 2% hydrogen) and cooling water tank in sequence. Supply argon to reduce the dissolved oxygen content inside the printer chamber to 250 ppm and the water tank temperature to 20℃. Open and download the pre-modeled internal porous 3D structure model. Use alternating scanning with equal intervals of 75° rotation in the X and Y directions. The scanning speed range is 800-1000 mm / s, the laser power range is 120-140 W, the scanning interval is 0.08-0.102 mm, the powder layer thickness is 0.05 mm, and the laser peak value is set to 100. Printing can only begin after the laser is turned on. S6. After 3D printing is completed, allow it to cool naturally, cut it, soak it in anhydrous ethanol, and ultrasonically clean it for 7 minutes. Repeat this process 2-3 times to remove surface oil and obtain a 3D printed zero-valent iron-doped electrode.

[0024] Example 2

[0025] A method for removing copper ions from wastewater, using a 3D-printed zero-valent iron-doped electrode prepared in Example 1 to remove copper ions from simulated wastewater, includes the following steps: (1) The 3D printed zero-valent iron doped electrode was immersed in 1% hydrochloric acid solution and ultrasonically treated for 5 minutes to remove the oxide layer on the surface of the 3D printed zero-valent iron doped electrode. (2) Prepare copper-containing simulated wastewater containing 3 g / L copper ions and 100 mM anhydrous sodium sulfate. Place the 3D-printed zero-valent iron-doped electrode with the oxide layer removed into an electrolytic cell containing the copper-containing simulated wastewater, and apply the solution at a current density of 30 mA / cm². 2 Under the condition of an initial pH of 5, electrodeposition was performed. 1 mL of the reaction solution was taken at different reaction times t, and the concentration of copper ions in the taken reaction solution was detected using an ICP instrument.

[0026] Example 3: Removal effect of 3D-printed zero-valent iron-doped electrode on copper wastewater of different concentrations

[0027] Using the 3D-printed zero-valent iron-doped electrode prepared in Example 1, copper wastewater of different concentrations was treated according to the method in Example 2. 1 mL of the reaction solution was collected at 30 min, 60 min, 90 min, and 120 min of the reaction, and the copper ion concentration in the collected reaction solution was detected using an ICP instrument. Specific results are shown in […]. Figure 1 .

[0028] Depend on Figure 1 It can be seen that in the simulated copper wastewater, the copper concentration is 3 g / L and the current density is 30 mA / cm². 2Under conditions of 100 mM Na₂SO₄ and an initial pH of 5, the 3D-printed zero-valent iron-doped electrode of this invention can achieve an 89% removal rate of copper ions in wastewater within two hours. Under the same conditions, the removal rates of copper ions in copper-containing wastewater with copper concentrations of 0.3 g / L, 0.5 g / L, 1 g / L, and 2 g / L can reach 99.6%, 99.1%, 84.5%, and 92.2%, respectively.

[0029] Example 4: Effect of Nickel Oxide on the Removal Efficiency of Copper from Zero-Valence Iron-Doped Electrodes in 3D Printing

[0030] Zero-valent iron powder, carbon nanotubes, and soluble organic carbon were weighed at a mass ratio of 96:2:2. Following the preparation method of Example 1, a zero-valent iron-doped electrode without added nickel oxide was prepared. Following the method of Example 2, the removal efficiency of copper ions from wastewater by this zero-valent iron-doped electrode without added nickel oxide was compared with that of the 3D-printed zero-valent iron-doped electrode prepared in Example 1. Specific results are shown in […]. Figure 2 .

[0031] Depend on Figure 2 It can be seen that the 3D-printed zero-valent iron doped electrode with added nickel oxide has a significantly higher effect on the removal of copper ions in wastewater than the zero-valent iron doped electrode without added nickel oxide, indicating that nickel oxide has a positive effect on improving the copper removal efficiency of the 3D-printed zero-valent iron doped electrode.

[0032] Example 5: Effect of different nickel oxide addition amounts on copper removal efficiency of zero-valent iron-doped electrodes in 3D printing

[0033] To compare the effect of different nickel oxide addition amounts on the copper removal efficiency of 3D-printed zero-valent iron doped electrodes, four treatments with different nickel oxide addition amounts were set up. The raw material composition of each treatment was as follows: Treatment 1 (1% nickel oxide, 2% carbon nanotubes, 2% soluble organic carbon, 95% zero-valent iron powder), Treatment 2 (3% nickel oxide, 2% carbon nanotubes, 2% soluble organic carbon, 93% zero-valent iron powder), Treatment 3 (5% nickel oxide, 2% carbon nanotubes, 2% soluble organic carbon, 91% zero-valent iron powder), and Treatment 4 (7% nickel oxide, 2% carbon nanotubes, 2% soluble organic carbon, 89% zero-valent iron powder). Zero-valent iron doped electrodes with different nickel oxide contents were prepared according to the preparation method of Example 1. Then, according to the method of Example 2, the removal efficiency of these zero-valent iron doped electrodes with different nickel oxide contents for copper ions in wastewater was measured and compared. Specific results are shown in […]. Figure 3 .

[0034] Depend on Figure 3It can be seen that the zero-valent iron doped electrode with 5% nickel oxide content prepared in this embodiment has the highest removal efficiency of copper ions in wastewater, which is significantly better than the zero-valent iron doped electrodes of the other three treatments. Therefore, the optimal amount of nickel oxide added when preparing the 3D printed zero-valent iron doped electrode is determined to be 5%.

[0035] Example 6: Effect of different carbon nanotube addition amounts on copper removal efficiency of zero-valent iron-doped electrodes in 3D printing

[0036] To compare the effect of different carbon nanotube addition amounts on the copper removal efficiency of 3D-printed zero-valent iron-doped electrodes, four treatments with different carbon nanotube addition amounts were set up. The raw material composition of each treatment was as follows: Treatment 1 (0.5% carbon nanotubes, 2% soluble organic carbon, 5% nickel oxide, 92.5% zero-valent iron), Treatment 2 (1% carbon nanotubes, 2% soluble organic carbon, 5% nickel oxide, 92% zero-valent iron), Treatment 3 (2% carbon nanotubes, 2% soluble organic carbon, 5% nickel oxide, 91% zero-valent iron), and Treatment 4 (3% carbon nanotubes, 2% soluble organic carbon, 5% nickel oxide, 90% zero-valent iron). Zero-valent iron-doped electrodes with different carbon nanotube contents were prepared according to the preparation method of Example 1. Then, according to the method of Example 2, the removal efficiency of these zero-valent iron-doped electrodes with different carbon nanotube contents for copper ions in wastewater was measured and compared. Specific results are shown in […]. Figure 4 .

[0037] Depend on Figure 4 It can be seen that when the carbon nanotube addition amount is 2% and 3%, the removal efficiency of the zero-valent iron doped electrode for copper ions in wastewater is basically the same, and significantly higher than that of the zero-valent iron doped electrode with carbon nanotube addition amount of 0.5% and 1%. Therefore, the optimal addition amount of carbon nanotubes for preparing the 3D printed zero-valent iron doped electrode is determined to be 2%.

[0038] Example 7: Effect of different amounts of soluble organic carbon added on the removal efficiency of copper in 3D printed zero-valent iron-doped electrodes

[0039] To compare the effect of different amounts of soluble organic carbon added on the copper removal efficiency of 3D-printed zero-valent iron-doped electrodes, four treatments with different amounts of soluble organic carbon were set up. The raw material composition of each treatment was as follows: Treatment 1 (0.5% soluble organic carbon, 2% carbon nanotubes, 5% nickel oxide, 92.5% zero-valent iron), Treatment 2 (1% soluble organic carbon, 2% carbon nanotubes, 5% nickel oxide, 92% zero-valent iron), Treatment 3 (2% soluble organic carbon, 2% carbon nanotubes, 5% nickel oxide, 91% zero-valent iron), and Treatment 4 (3% soluble organic carbon, 2% carbon nanotubes, 5% nickel oxide, 90% zero-valent iron). Zero-valent iron-doped electrodes with different soluble organic carbon contents were prepared according to the preparation method in Example 1. Then, according to the method in Example 2, the removal efficiency of these zero-valent iron-doped electrodes with different soluble organic carbon contents for copper ions in wastewater was measured and compared. Specific results are shown in […]. Figure 5 .

[0040] Depend on Figure 5 It can be seen that when the amount of soluble organic carbon added is 2%, the zero-valent iron-doped electrode prepared has the highest removal efficiency of copper ions in wastewater, which is significantly higher than that of zero-valent iron-doped electrodes with soluble organic carbon added of 0.5% and 1%. However, when the amount of soluble organic carbon added is increased to 3%, the removal efficiency of copper ions in wastewater by the prepared zero-valent iron-doped electrode decreases. Therefore, the optimal amount of soluble organic carbon added in the preparation of the 3D printed zero-valent iron-doped electrode is determined to be 2%.

[0041] The above descriptions are merely some embodiments of the present invention. For those skilled in the art, various modifications and improvements can be made without departing from the inventive concept of the present invention, and these all fall within the protection scope of the present invention.

Claims

1. A method for preparing a 3D-printed zero-valent iron-doped electrode for removing copper ions from wastewater, characterized in that, Includes the following steps: S1. Place zero-valent iron powder, nickel oxide powder, carbon nanotubes and soluble organic carbon into a container according to a certain mass ratio, add pure water to react, let stand for 12 hours, when the container shows stratification and the upper layer is clear, pour out the upper liquid and keep the lower aggregate. S2. The aggregate is added to a planetary ball mill jar pre-filled with ball milling steel balls and ball milled alternately in forward and reverse directions to obtain uniformly mixed spherical iron powder; S3. The spherical iron powder is placed in an oven and dried, and then mechanically sieved to obtain mixed spherical zero-valent iron powder; S4. Select a metal laser 3D printing equipment, install the metal printing plate of the printing equipment and level it so that the four planes of the printing plate are parallel. Install the powder spreading scraper, make it parallel to the printing plate and lower it to the position where it just touches the printing plate. S5. Pour the mixed spherical zero-valent iron powder into the powder tank of the 3D printing equipment, turn on the protective gas and cooling water tank in sequence, and supply argon gas to reduce the dissolved oxygen content in the printer chamber to 250 ppm and the water tank temperature to 20℃. Open and download the pre-modeled internal porous 3D structure model, and use alternating scanning with equal intervals of 75° in the X and Y directions. The scanning speed range is 800~1000 mm / s, the laser power range is 120~140 W, the scanning interval is 0.08~0.102 mm, the powder layer thickness is 0.05 mm, the laser peak value is set to 100, and printing can only be started after the laser is turned on. S6. After 3D printing is completed, allow it to cool naturally, cut it, soak it in anhydrous ethanol, and ultrasonically clean it to remove surface oil and obtain a 3D printed zero-valent iron-doped electrode.

2. The method for preparing a 3D-printed zero-valent iron-doped electrode for removing copper ions from wastewater according to claim 1, characterized in that, In step S1, the mass ratio of zero-valent iron powder, nickel oxide powder, carbon nanotubes, and soluble organic carbon is 91:5:2:

2.

3. The method for preparing a 3D-printed zero-valent iron-doped electrode for removing copper ions from wastewater according to claim 1, characterized in that, In step S2, the mass ratio of the milling steel balls to the aggregate is 4:1, and the duration of the alternating forward and reverse milling is 2 hours.

4. The method for preparing a 3D-printed zero-valent iron-doped electrode for removing copper ions from wastewater according to claim 1, characterized in that, The drying temperature in step S3 is 60-65℃, and the drying time is 3-5 hours.

5. The method for preparing a 3D-printed zero-valent iron-doped electrode for removing copper ions from wastewater according to claim 1, characterized in that, The mesh size of the sieve used for mechanical sieving in step S3 is 200 mesh.

6. The method for preparing a 3D-printed zero-valent iron-doped electrode for removing copper ions from wastewater according to claim 1, characterized in that, In step S5, the protective gas is a mixture of 98% argon and 2% hydrogen.

7. A 3D-printed zero-valent iron-doped electrode prepared by any one of the preparation methods of a 3D-printed zero-valent iron-doped electrode for removing copper ions from wastewater according to any one of claims 1 to 6.

8. The application of the 3D-printed zero-valent iron-doped electrode prepared by the method for preparing a 3D-printed zero-valent iron-doped electrode for removing copper ions from wastewater according to any one of claims 1 to 6 in the removal of copper ions from wastewater.

9. A method for removing copper ions from wastewater, characterized in that, The 3D-printed zero-valent iron-doped electrode for removing copper ions from wastewater, prepared by any one of the methods described in claims 1 to 6, removes copper ions from wastewater, comprising the following steps: (1) The 3D printed zero-valent iron doped electrode was immersed in 1% hydrochloric acid solution and ultrasonically treated for 5 minutes to remove the oxide layer on the surface of the 3D printed zero-valent iron doped electrode. (2) The 3D-printed zero-valent iron-doped electrode with the oxide layer removed is placed in an electrolytic cell containing copper-containing simulated wastewater, and the current density is 30 mA / cm². 2 Under the condition of initial pH value of 5, electrodeposition treatment was carried out. 1 mL of reaction solution was taken at different reaction times t, and the concentration of copper ions in the taken reaction solution was detected by ICP instrument.

10. A method for removing copper ions from wastewater according to claim 9, characterized in that, The copper-containing simulated wastewater is simulated wastewater containing 3 g / L copper ions and 100 mM anhydrous sodium sulfate.

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