Recycling treatment method and device for heavy metal electroplating wastewater

Abstract

The invention discloses a method and a device for recycling electroplating wastewater. The method comprises the following steps: arranging an electrolytic tank; the electrolytic tank comprises a cathode chamber, an anode chamber and a cationic membrane for separating the cathode chamber from the anode chamber; and adding the heavy metal electroplating wastewater into the cathode chamber, applying current to the cathode chamber to generate hydrogen and the nanoparticle precipitate of the heavy metal hydroxide, and respectively recovering the hydrogen and the nanoparticle precipitate of the heavy metal hydroxide to finish the treatment. The method disclosed by the invention can be used for precipitating metal ions by utilizing residual hydroxyl radicals in the electrolytic solution and recycling heavy metal ions in the electroplating wastewater in a nano-particle precipitation manner by taking electrolysis to desorb hydrogen as a purpose; and meanwhile, the nano-particle precipitation is utilized, so that the electrolytic reaction can be promoted.

Description

Technical Field

[0001] The invention relates to the technical field of electroplating wastewater recovery, and in particular to a method and device for recovering heavy metal electroplating wastewater. Background Art

[0002] Each production link in the electroplating process will generate wastewater. Not only is the amount of wastewater large, but also there are many types of wastewater, including pre-plating oil removal wastewater, organic matter removal wastewater, plated parts rinsing wastewater, tank washing wastewater, waste plating liquid, and laboratory water wastewater.

[0003] There are many types of pollutants in electroplating wastewater, most of which are difficult to degrade naturally and can be widely spread through natural media such as water, soil or air. If water or soil is polluted by electroplating wastewater for a long time, the consequences will be extremely serious for both humans and the natural environment. Heavy metal wastewater is one of the wastewaters produced in large quantities in the electroplating industry. At present, the common treatment methods for heavy metal electroplating wastewater include precipitation, membrane separation, electrolysis and adsorption. The electrochemical method mainly uses a reactor with an external electric field to cause electron migration of pollutants on the electrode surface, thereby achieving the purpose of eliminating, denaturing or separating pollutants. Compared with the traditional chemical precipitation method with added reagents, this technology achieves zero reagent addition to recover metal copper resources, and at the same time uses the hydrogen evolution reaction at the cathode to recover hydrogen energy, thereby increasing the resource utilization rate of wastewater.

[0004] Existing methods for treating electrolytic and electroplating wastewater usually do not involve the preparation of hydrogen. In order to avoid the production of hydrogen, operations such as reducing the current density are taken to complete the precipitation treatment of metal elements in the electroplating wastewater. Therefore, there is a problem of low resource utilization rate of wastewater. Summary of the invention

[0005] In order to solve the above problems, the present invention provides a method and device for recycling heavy metal electroplating wastewater.

[0006] A method for recycling heavy metal electroplating wastewater comprises the following steps:

[0007] An electrolytic cell is provided; the electrolytic cell comprises a cathode chamber, an anode chamber and a cationic membrane for separating the cathode chamber from the anode chamber; a cathode plate is provided in the cathode chamber, an anode plate is provided in the anode chamber, and the cathode plate and the anode plate are connected through a power supply;

[0008] Add heavy metal electroplating wastewater into the cathode chamber and apply 10-1000 mA / cm 2 The current is passed to the cathode chamber to produce hydrogen and nanoparticle precipitation of heavy metal hydroxide, and the hydrogen and nanoparticle precipitation of heavy metal hydroxide are recovered respectively. The processing time is 30 to 120 minutes.

[0009] Description: The above method can be used to electrolyze hydrogen, utilize the remaining hydroxide in the electrolytic solution to precipitate metal ions, and recover heavy metal ions in electroplating wastewater in the form of nanoparticle precipitation.

[0010] Furthermore, the method further comprises: adjusting the pH value of the heavy metal electroplating wastewater to 6-13.

[0011] Furthermore, the method further comprises:

[0012] In the process of applying current, the morphology of the precipitated nanoparticles of heavy metal hydroxide is adjusted by changing the electrolysis conditions. The morphology of the precipitated nanoparticles of heavy metal hydroxide includes flake, spherical, rod or tubular.

[0013] Description: Through the above-mentioned morphology, the collected heavy metal hydroxide can have a better morphology, and different morphologies have different effects, which is convenient for the reuse of recovered products. At the same time, these morphologies can promote the electrolysis reaction. Since the nanoparticles have good catalytic performance, large surface area, more active sites, higher stability and electron transmission functions, in the electrolysis hydrogenation reaction, nanoparticles of various morphologies can significantly improve the preparation efficiency of electrolysis hydrogenation.

[0014] Furthermore, the method for adjusting the morphology of the heavy metal hydroxide nanoparticle precipitation by changing the electrolysis conditions includes:

[0015] When the desired morphology of the heavy metal hydroxide nanoparticles precipitate is flake-shaped, the electrolysis conditions are changed by: reducing the current density and adding the first auxiliary agent;

[0016] When the desired morphology of the heavy metal hydroxide nanoparticles precipitated is spherical, the changing of the electrolysis conditions is: adjusting the pH value of the electrolyte and adding a second auxiliary agent;

[0017] When the desired morphology of the heavy metal hydroxide nanoparticles precipitated is rod-shaped, the changing of the electrolysis conditions comprises: changing the current waveform and adding a third auxiliary agent, wherein the current waveform comprises a pulse current or an alternating current;

[0018] When the desired morphology of the heavy metal hydroxide nanoparticles precipitated is tubular, the electrolysis conditions are changed by adjusting the concentration of the heavy metal electroplating wastewater and adding a fourth auxiliary agent.

[0019] Note: Experiments have shown that for electroplating wastewater, the generation conditions of nanoparticles with different morphologies have different focuses, and the catalytic properties of different nanoparticles are also different. Among them, the nanoparticles obtained according to the above conditions are better at promoting electrolysis reactions and have higher recovery value.

[0020] Furthermore, the first auxiliary agent is a surfactant, the second auxiliary agent is a stabilizer, the third auxiliary agent is a growth agent, and the fourth auxiliary agent is a structure-directing agent; wherein the surfactant is sodium dodecyl sulfate or sodium stearate, the stabilizer is polyacrylic acid or polyvinyl pyrrolidone; the growth agent is collagen or fibrin, and the structure-directing agent is carbon nanotubes.

[0021] Note: Experiments have shown that the above-mentioned additives can promote the formation of various nanoparticle forms.

[0022] Furthermore, when the heavy metal electroplating wastewater contains copper ions, the applied current density is 30 mA / cm 2 ,

[0023] When the morphology of the heavy metal hydroxide nanoparticles is flake-shaped, the electrolysis conditions are changed to: 0.8-1 mA / cm per minute 2 The current density was reduced to 10 mA / cm 2 , then adding the first auxiliary agent accounting for 0.1% of the mass of the heavy metal electroplating wastewater;

[0024] When the desired morphology of the heavy metal hydroxide nanoparticles precipitated is spherical, the electrolysis conditions are changed as follows: adjusting the pH value of the electrolyte to 8-11, adding the second auxiliary agent accounting for 0.1% of the mass of the heavy metal electroplating wastewater;

[0025] When the desired morphology of the heavy metal hydroxide nanoparticles precipitated is rod-shaped, the electrolysis condition is changed by: changing the current waveform, adding the third auxiliary agent accounting for 0.1% of the mass of the heavy metal electroplating wastewater, the current is a pulse current, and the current waveform is changed by changing the frequency of the pulse current;

[0026] When the desired morphology of the heavy metal hydroxide nanoparticle precipitation is tubular, the electrolysis conditions are changed as follows: diluting the concentration of the heavy metal electroplating wastewater to 80% of the original heavy metal electroplating wastewater concentration and adding the fourth auxiliary agent accounting for 0.1% of the mass of the heavy metal electroplating wastewater.

[0027] Note: The above method provides a feasible way to obtain various nanoparticle forms when heavy metal electroplating wastewater contains copper ions.

[0028] Furthermore, while applying the current, the nanoparticle precipitate of the heavy metal hydroxide in the cathode chamber is recovered to ensure that the volume of the nanoparticle precipitate of the heavy metal hydroxide in the cathode chamber is 3-8% of the volume of the cathode chamber.

[0029] Note: The above-mentioned setting of the volume of nanoparticles has a better promoting effect on the electrolytic hydrogen evolution reaction. Beyond this range, the effect decreases. Too much may interfere with the electrolytic reaction, and too little may not have a significant effect.

[0030] Furthermore, the carbon nanotubes are modified with CdTe / CdSe core-shell quantum dots.

[0031] The steps for preparing the carbon nanotubes modified with CdTe / CdSe core-shell quantum dots are as follows:

[0032] (1) Pretreatment of carbon nanotubes

[0033] Dispersing carbon nanotubes in ethanol at a volume fraction of 25%, and then performing ultrasonic treatment to obtain a carbon nanotube solution;

[0034] (2) CdTe core quantum dots were synthesized by a solution method, cadmium chloride, sodium telluride, ethanol, and octadecene were mixed in a ratio of 1 mmol: 1 mmol: 10 mL: 2 mL, and reacted at 250 °C for 30 min to form a mixed system;

[0035] (3) adding selenium powder and cadmium chloride dropwise to the mixed system in a ratio of 10 mL: 0.05 mmol: 0.05 mmol, and reacting at 200° C. for 60 min, wherein the pH value during the reaction is controlled between 7 and 9, to obtain a CdTe / CdSe quantum dot solution;

[0036] (4) Mixing the CdTe / CdSe quantum dot solution and the carbon nanotube solution in a molar ratio of 1:1, ultrasonically treating the mixture, the ultrasonic treatment power is 100-200 W, and then conducting a 20 mW / cm 2 The reaction was completed after irradiation for 15 min under a light intensity of , and then the carbon nanotubes modified with CdTe / CdSe core-shell quantum dots were obtained by washing and drying.

[0037] Description: Through the above method, CdTe / CdSe quantum dots can serve as a bridge for electron transmission, improve the conductivity and stability of carbon nanotubes, and promote the precipitation of heavy metal hydroxide nanoparticles to form a tubular morphology.

[0038] A heavy metal electroplating wastewater recovery and treatment device is used to implement the above-mentioned heavy metal electroplating wastewater recovery and treatment method, the device comprises a cathode chamber, an anode chamber and a cationic membrane for separating the cathode chamber and the anode chamber, a cathode plate is arranged in the cathode chamber, an anode plate is arranged in the anode chamber, the cathode plate and the anode plate are connected through a power supply, and the anode plate is parallel to the bottom surface of the cathode chamber.

[0039] Furthermore, the top of the cathode chamber is connected to a first outlet for discharging hydrogen, the bottom of the cathode chamber is provided with a second outlet for discharging treated electroplating wastewater, and the bottom of the anode chamber is provided with a third outlet for discharging treated electroplating wastewater;

[0040] The cathode chamber is provided with a scraper for scraping the nanoparticle precipitation of the heavy metal hydroxide toward one side of the cathode chamber. The scraper is perpendicular to the bottom surface of the cathode chamber, and the scraper is slidably connected to the bottom surface of the cathode chamber via a slide groove and a slide rail.

[0041] Furthermore, a partition mechanism is provided above the scraper, and the partition mechanism includes a plurality of partitions, the rotating shaft of the partition is rotatably connected to the side of the cathode chamber, and a gear is sleeved on the rotating shaft of each partition, and a rack for meshing and transmitting the gear is slidably connected to the side of the cathode chamber, and the top of the scraper is the same height as the partition when it is rotated to the horizontal;

[0042] The scraper is provided with a plurality of through holes, each of which is provided with a filter membrane for filtering the nanoparticle precipitation of heavy metal hydroxides in water; the scraper is connected to the other side of the cathode chamber via a first spring;

[0043] A fourth outlet for discharging the nanoparticle precipitation of the heavy metal hydroxide is provided at one side of the cathode chamber, and a valve is provided at the fourth outlet, and the valve is hinged to the bottom end of the fourth outlet through a hinged rod;

[0044] When it is necessary to collect the nanoparticle precipitate of heavy metal hydroxide, the rack is meshed with the gear for transmission, the partition is parallel to the bottom surface of the cathode chamber, the multiple partitions are used to separate the upper area and the lower area of ​​the cathode chamber, and block the liquid in the upper area from flowing to the lower area, and the scraper is driven to move electrically or manually, and the scraper pushes the nanoparticle precipitate of heavy metal hydroxide between the partition and the cathode chamber to the fourth outlet;

[0045] After the collection of the heavy metal hydroxide nanoparticles is completed, the scraper is reset by the first spring, and the rack is moved to rotate the gear, and the partition is rotated 90 degrees and then restored to the initial state.

[0046] A scribing blade for blocking the through hole is slidably arranged on the scraper, the scribing blade is connected to the scraper via a second spring, the scribing blade is made of magnetic material, and a magnet for driving the scribing blade to move to block the through hole is arranged on the bottom surface of one side of the cathode chamber.

[0047] Description: Through the arrangement of the partition mechanism and the gear rack, the nanoparticle precipitate of the heavy metal hydroxide can be easily collected to keep the nanoparticle precipitate of the heavy metal hydroxide in the cathode chamber at an appropriate amount, thereby promoting the electrolytic treatment of electroplating wastewater.

[0048] The beneficial effects of the present invention are:

[0049] The method of the present invention can be used for the purpose of electrolytic hydrogen evolution, and the residual hydroxide in the electrolytic solution is used to precipitate metal ions, and the heavy metal ions in the electroplating wastewater are recovered in the form of nanoparticle precipitation, so as to solve the problem of low resource utilization rate of wastewater; at the same time, the nanoparticle precipitation is used to promote the electrolytic reaction, and since the nanoparticles have good catalytic performance, large surface area, more active sites, higher stability and functions such as electron transmission, in the electrolytic hydrogen evolution reaction, nanoparticles with various morphologies can significantly improve the preparation efficiency of electrolytic hydrogen evolution. BRIEF DESCRIPTION OF THE DRAWINGS

[0050] Figure 1 It is a schematic diagram of the reaction principle of an embodiment of the present invention;

[0051] Figure 2 This is a SEM schematic diagram of the precipitation of nanoparticles of flaky heavy metal hydroxides in Example 1;

[0052] Figure 3 This is a schematic diagram of the appearance of a heavy metal electroplating wastewater recovery and treatment device of Example 11;

[0053] Figure 4 This is an internal schematic diagram of a heavy metal electroplating wastewater recovery and treatment device of Example 11;

[0054] Figure 5 This is a schematic diagram of the interior of the cathode chamber of the heavy metal electroplating wastewater recovery and treatment device of Example 11;

[0055] Figure 6 This is the second schematic diagram of the interior of the cathode chamber of the heavy metal electroplating wastewater recovery and treatment device of Example 11;

[0056] Figure 7 This is a schematic diagram of the scraper structure of the heavy metal electroplating wastewater recovery and treatment device of Example 11;

[0057] In the figure, 1-recycling device, 11-first outlet, 12-second outlet, 13-third outlet, 14-fourth outlet, 15-cathode plate, 16-anode plate, 17-magnet, 2-partition mechanism, 21-partition, 22-scraper, 221 through hole, 222-slice, 223-second spring, 224 telescopic rod, 23-rack, 24-gear, 25-first spring. DETAILED DESCRIPTION

[0058] In order to further illustrate the method adopted by the present invention and the effect achieved, the technical solution of the present invention will be clearly and completely described in combination with experiments below.

[0059] Embodiment 1: A method for recycling heavy metal electroplating wastewater, comprising the following steps:

[0060] like Figure 1 As shown, an electrolytic cell is provided; the electrolytic cell comprises a cathode chamber, an anode chamber and a cation membrane for separating the cathode chamber from the anode chamber; a cathode plate is provided in the cathode chamber, an anode plate is provided in the anode chamber, and the cathode plate and the anode plate are connected through a power supply;

[0061] Adding heavy metal electroplating wastewater into the cathode chamber, applying and adjusting current to generate hydrogen and heavy metal hydroxide nanoparticle precipitation in the cathode chamber, respectively recovering hydrogen and heavy metal hydroxide nanoparticle precipitation to complete the treatment;

[0062] The applied current is 50 mA / cm 2 The pH value of the heavy metal electroplating wastewater is adjusted to 10; in the process of applying current, the morphology of the nanoparticles of heavy metal hydroxide precipitation is adjusted by changing the electrolysis conditions, and the morphology of the nanoparticles of heavy metal hydroxide precipitation includes flake, spherical, rod or tubular; the heavy metal electroplating wastewater contains copper ions, and the applied current density is 30mA / cm 2 The morphology of the heavy metal hydroxide nanoparticle precipitation is flake-like; Figure 2 As shown; the electrolysis conditions are changed to: 0.9 mA / cm per minute 2 The current density was reduced to 10 mA / cm 2 , then adding a first auxiliary agent accounting for 0.1% of the mass of the heavy metal electroplating wastewater, the first auxiliary agent being sodium dodecyl sulfate;

[0063] While applying the current, the nanoparticle precipitate of the heavy metal hydroxide in the cathode chamber is recovered to ensure that the volume of the nanoparticle precipitate of the heavy metal hydroxide in the cathode chamber is 5% of the volume of the cathode chamber.

[0064] Example 2: This example is different from Example 1 in that the applied current is 10 mA / cm 2 ; The pH of the heavy metal electroplating wastewater was adjusted to 13; the electrolysis conditions were changed to 0.8 mA / cm per minute 2 The current density was reduced to 10 mA / cm 2The volume of the heavy metal hydroxide nanoparticles precipitated in the cathode chamber is 8% of the volume of the cathode chamber.

[0065] Example 3: This example is different from Example 1 in that the applied current is 1000 mA / cm 2 ; The pH of the heavy metal electroplating wastewater was adjusted to 6; the electrolysis conditions were changed to: 1 mA / cm per minute 2 The current density was reduced to 10 mA / cm 2 The volume of the heavy metal hydroxide nanoparticles precipitated in the cathode chamber is 3% of the volume of the cathode chamber.

[0066] Example 4: This example is different from Example 1 in that the first auxiliary agent is sodium stearate.

[0067] Example 5: This example is different from Example 1 in that the desired morphology of the heavy metal hydroxide nanoparticle precipitate is spherical, and the changing of the electrolysis conditions is to adjust the pH value of the electrolyte and add a second auxiliary agent accounting for 0.1% of the mass of the heavy metal electroplating wastewater, wherein the second auxiliary agent is polyacrylic acid, and the pH value of the electrolyte is adjusted to within the range of 8 to 11, which can be achieved by adding sodium hydroxide or nitric acid.

[0068] Example 6: This example is different from Example 5 in that the second auxiliary agent is polyvinyl pyrrolidone.

[0069] Example 7: This example is different from Example 1 in that the desired morphology of the heavy metal hydroxide nanoparticle precipitate is rod-shaped, and the changing of the electrolysis conditions is to change the current waveform and add a third auxiliary agent accounting for 0.1% of the mass of the heavy metal electroplating wastewater, the third auxiliary agent is fibrin, the current is a pulse current, and the changing of the current waveform is to change the frequency of the pulse current; changing the frequency of the pulse current is achieved by pulse width modulation (PWM) control.

[0070] Example 8: This example is different from Example 7 in that the third auxiliary agent is collagen.

[0071] Example 9: This example is different from Example 1 in that the desired morphology of the heavy metal hydroxide nanoparticle precipitate is tubular, and the changing of the electrolysis conditions is to adjust the concentration of the electrolytic cell and add a fourth auxiliary agent, wherein the fourth auxiliary agent is carbon nanotubes. The specific adjustment of the electrolytic cell concentration is achieved by adding water (or in another implementation method, evaporation can be added to reduce water).

[0072] Example 10: This example is different from Example 1 in that the carbon nanotubes are modified with CdTe / CdSe core-shell quantum dots.

[0073] The steps for preparing the carbon nanotubes modified with CdTe / CdSe core-shell quantum dots are as follows:

[0074] (1) Pretreatment of carbon nanotubes

[0075] Dispersing carbon nanotubes in ethanol at a volume fraction of 25%, and then performing ultrasonic treatment to obtain a carbon nanotube solution;

[0076] (2) CdTe core quantum dots were synthesized by a solution method, cadmium chloride, sodium telluride, ethanol, and octadecene were mixed in a ratio of 1 mmol: 1 mmol: 10 mL: 2 mL, and reacted at 250 °C for 30 min to form a mixed system;

[0077] (3) adding selenium powder and cadmium chloride dropwise to the mixed system in a ratio of 10 mL: 0.05 mmol: 0.05 mmol, and reacting at 200° C. for 60 min, wherein the pH value during the reaction is controlled between 7 and 9, to obtain a CdTe / CdSe quantum dot solution;

[0078] (4) The CdTe / CdSe quantum dot solution and the carbon nanotube solution were mixed at a molar ratio of 1:1, and ultrasonically treated at a power of 150 W, and then subjected to a 20 mW / cm 2 The reaction was completed after irradiation for 15 min under a light intensity of , and then the carbon nanotubes modified with CdTe / CdSe core-shell quantum dots were obtained by washing and drying.

[0079] Experimental Example: The description of this experimental example is based on the scheme described in Example 1, and is intended to illustrate the practical application effect of the present invention.

[0080] 1. Taking electroplating wastewater mainly containing copper as an example, it is recycled and treated. It is found through experiments that the heavy metal removal rate of the heavy metal electroplating wastewater in the embodiment exceeds 99%; and the efficiency is relatively high, and the heavy metal removal rate can reach more than 85% within 1 hour;

[0081] 1. Explore the effect of different treatment conditions on heavy metal removal efficiency after 40 minutes of electrolytic treatment;

[0082] Comparative Example 1: The difference from Example 1 is that according to the existing method for electrolytic precipitation of metal elements, at a current of 3 mA / cm 2 The electrolytic treatment is carried out until a metal element is precipitated on the cathode.

[0083] Example 1, Example 5, Example 7 are compared with Example 9 and Comparative Example 1, as shown in Table 1;

[0084] Table 1 Experimental results of heavy metal removal efficiency under different treatment conditions

[0085]

[0086]

[0087] As can be seen from Table 1, by comparing Example 1 with Comparative Example 1, it can be seen that the efficiency of electrolysis at 40 min in Example 1 of the present invention is 78%, which is significantly improved compared with Comparative Example 1. The principle may be that the current in Comparative Example 1 is small, and the precipitated metal element adheres to the cathode surface, resulting in subsequent electrolysis difficulties. At the same time, the heavy metal hydroxide nanoparticle precipitation in the present invention has a certain catalytic effect.

[0088] By comparing Example 1, Example 5, Example 7 and Example 9, it can be seen that the experimental results of these examples are relatively close and the efficiency is relatively high.

[0089] By comparing Example 1 with Example 10, it can be found that in Example 10, the carbon nanotubes are modified with CdTe / CdSe core-shell quantum dots, and the modification may enhance the guiding effect of the carbon nanotubes, thereby promoting the degradation reaction.

[0090] Embodiment 11

[0091] Accordingly, the embodiment of the present application provides a heavy metal electroplating wastewater recovery and treatment device, which is used to implement the above-mentioned heavy metal electroplating wastewater recovery and treatment method, such as Figure 3 , 4 As shown, the device 1 includes a cathode chamber, an anode chamber and a cationic membrane for separating the cathode chamber and the anode chamber. A cathode plate 15 is provided in the cathode chamber, and an anode plate 16 is provided in the anode chamber. The cathode plate and the anode plate are connected through a power supply, and the anode plate is parallel to the bottom surface of the cathode chamber.

[0092] The top of the cathode chamber is connected to a first outlet 11 for discharging hydrogen, the bottom of the cathode chamber is provided with a second outlet 12 for discharging treated electroplating wastewater, and the bottom of the anode chamber is provided with a third outlet 13 for discharging treated electroplating wastewater;

[0093] like Figure 5 , 6 As shown, a scraper 22 is provided in the cathode chamber for scraping the nanoparticles of the heavy metal hydroxide to one side of the cathode chamber, the scraper 22 is perpendicular to the bottom surface of the cathode chamber, and the scraper 22 is slidably connected to the bottom surface of the cathode chamber via a slide rail;

[0094] A partition mechanism 2 is provided above the scraper 22, and the partition mechanism 2 includes a plurality of partitions 21, the rotating shaft of the partition 21 is rotatably connected to the side of the cathode chamber, and a gear 24 is sleeved on the rotating shaft of each partition 21, and a rack 23 for meshing and transmitting the gear 24 is slidably connected to the side of the cathode chamber, and the top of the scraper 22 is at the same height as the partition 21 when it is rotated to the horizontal;

[0095] The scraper 22 is provided with a plurality of through holes 221, and each through hole 221 is provided with a filter membrane for filtering the nanoparticle precipitation of heavy metal hydroxide in water; the filter membrane is commercially available, and the scraper 22 moves slowly, and the scraper 22 is connected to the other side of the cathode chamber through a first spring 25;

[0096] A fourth outlet 14 for discharging the nanoparticle precipitation of the heavy metal hydroxide is provided on one side of the cathode chamber, and the fourth outlet 14 is provided with a valve, and the valve is hinged to the bottom end of the fourth outlet through a hinge rod; the fourth outlet 14 is the same size as the scraper 22 or the area of ​​the fourth outlet 14 is smaller than the area of ​​the scraper 22 (that is, the scraper 22 can be stuck in the fourth outlet 14 to prevent the liquid in the cathode chamber from flowing out);

[0097] like Figure 7 As shown, a scriber 222 for blocking the through hole is slidably provided on the scraper 22, and the scriber 222 is connected to the scraper 22 via a second spring 223. The scriber 222 is made of magnetic material, and a magnet 17 for driving the scriber to move to block the through hole is provided on the bottom surface of one side of the cathode chamber.

[0098] When it is necessary to collect the nanoparticle precipitate of heavy metal hydroxide, the rack 23 is meshed with the gear 24 for transmission, the partition 21 is parallel to the bottom surface of the cathode chamber, and the plurality of partitions 21 are used to separate the upper area and the lower area of ​​the cathode chamber, blocking the liquid in the upper area from flowing to the lower area, and the scraper 22 is driven by electric or manual means to move (for example, the telescopic rod 224 in the figure can be used to achieve this), and the scraper 22 pushes the nanoparticle precipitate of heavy metal hydroxide between the partition 21 and the cathode chamber to the fourth outlet 14;

[0099] After the collection of the heavy metal hydroxide nanoparticles is completed, the scraper 22 is reset by the first spring 25, and the rack 23 is moved to rotate the gear 24, and the partition 21 is rotated 90 degrees and then restored to the initial state.

[0100] By setting the partition mechanism 2 and the gear 24 and rack 23, the nanoparticle precipitate of the heavy metal hydroxide can be easily collected to keep the nanoparticle precipitate of the heavy metal hydroxide in the cathode chamber at an appropriate amount, thereby promoting the electrolytic treatment of electroplating wastewater.

Claims

1. A method for recycling heavy metal electroplating wastewater, characterized in that: The following steps are involved: An electrolytic cell is provided; the electrolytic cell comprises a cathode chamber, an anode chamber and a cationic membrane for separating the cathode chamber from the anode chamber; a cathode plate is provided in the cathode chamber, an anode plate is provided in the anode chamber, and the cathode plate and the anode plate are connected through a power supply; Add heavy metal electroplating wastewater into the cathode chamber and apply 10-1000 mA / cm 2 The current is passed to the cathode chamber to produce hydrogen and nanoparticle precipitation of heavy metal hydroxide, and the hydrogen and nanoparticle precipitation of heavy metal hydroxide are recovered respectively. The processing time is 30 to 120 minutes.

2. The method for recycling heavy metal electroplating wastewater according to claim 1, characterized in that: Also includes: The pH of the heavy metal electroplating wastewater is adjusted to 6-13.

3. The method for recycling heavy metal electroplating wastewater according to claim 1, characterized in that: The method further comprises: In the process of applying current, the morphology of the precipitated nanoparticles of heavy metal hydroxide is adjusted by changing the electrolysis conditions. The morphology of the precipitated nanoparticles of heavy metal hydroxide includes flake, spherical, rod or tubular.

4. A method for recycling heavy metal electroplating wastewater as claimed in claim 3, characterized in that: The method for adjusting the morphology of the heavy metal hydroxide nanoparticle precipitation by changing the electrolysis conditions comprises: When the desired morphology of the heavy metal hydroxide nanoparticles precipitate is flake-shaped, the electrolysis conditions are changed by: reducing the current density and adding the first auxiliary agent; When the desired morphology of the heavy metal hydroxide nanoparticles precipitated is spherical, the changing of the electrolysis conditions is: adjusting the pH value of the electrolyte and adding a second auxiliary agent; When the desired morphology of the heavy metal hydroxide nanoparticles precipitated is rod-shaped, the changing of the electrolysis conditions comprises: changing the current waveform and adding a third auxiliary agent, wherein the current waveform comprises a pulse current or an alternating current; When the desired morphology of the heavy metal hydroxide nanoparticles precipitated is tubular, the electrolysis conditions are changed by adjusting the concentration of the heavy metal electroplating wastewater and adding a fourth auxiliary agent.

5. A method for recycling heavy metal electroplating wastewater as claimed in claim 4, characterized in that: The first auxiliary agent is a surfactant, the second auxiliary agent is a stabilizer, the third auxiliary agent is a growth agent, and the fourth auxiliary agent is a structure-directing agent; wherein the surfactant is sodium dodecyl sulfate or sodium stearate, the stabilizer is polyacrylic acid or polyvinyl pyrrolidone; the growth agent is collagen or fibrin, and the structure-directing agent is carbon nanotubes.

6. A method for recycling heavy metal electroplating wastewater as claimed in claim 4, characterized in that: When the heavy metal electroplating wastewater contains copper ions, the applied current density is 30 mA / cm 2 , When the morphology of the heavy metal hydroxide nanoparticles is flake-shaped, the electrolysis conditions are changed to: 0.8-1 mA / cm per minute 2 The current density was reduced to 10 mA / cm 2 , then adding the first auxiliary agent accounting for 0.1% of the mass of the heavy metal electroplating wastewater; When the desired morphology of the heavy metal hydroxide nanoparticles precipitated is spherical, the electrolysis conditions are changed as follows: adjusting the pH value of the electrolyte to 8-11, adding the second auxiliary agent accounting for 0.1% of the mass of the heavy metal electroplating wastewater; When the desired morphology of the heavy metal hydroxide nanoparticles precipitated is rod-shaped, the electrolysis condition is changed by: changing the current waveform, adding the third auxiliary agent accounting for 0.1% of the mass of the heavy metal electroplating wastewater, the current is a pulse current, and the current waveform is changed by changing the frequency of the pulse current; When the desired morphology of the heavy metal hydroxide nanoparticle precipitation is tubular, the electrolysis conditions are changed as follows: diluting the concentration of the heavy metal electroplating wastewater to 80% of the original heavy metal electroplating wastewater concentration and adding the fourth auxiliary agent accounting for 0.1% of the mass of the heavy metal electroplating wastewater.

7. The method for recycling heavy metal electroplating wastewater according to claim 1, characterized in that: The carbon nanotubes are modified with CdTe / CdSe core-shell quantum dots.

8. The method for recycling heavy metal electroplating wastewater according to claim 1, characterized in that: While applying the current, the nanoparticle precipitate of the heavy metal hydroxide in the cathode chamber is recovered to ensure that the volume of the nanoparticle precipitate of the heavy metal hydroxide in the cathode chamber is 3-8% of the volume of the cathode chamber.

9. A heavy metal electroplating wastewater recovery and treatment device, used to implement a heavy metal electroplating wastewater recovery and treatment method according to any one of claims 1 to 8, characterized in that: The device comprises a cathode chamber, an anode chamber and a cationic membrane for separating the cathode chamber and the anode chamber. A cathode plate is arranged in the cathode chamber, an anode plate is arranged in the anode chamber, the cathode plate and the anode plate are connected through a power supply, and the anode plate is parallel to the bottom surface of the cathode chamber.

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