Multi-stage electrochemical reactor and method for treating heavy metal complex and recovering heavy metal

Abstract

The invention discloses a multistage electrochemical reactor and method for treating a heavy metal complex and recovering heavy metals, and belongs to the technical field of electrochemical water purification, the multistage electrochemical reactor comprises a reactor body, a reactor bracket is arranged below the reactor, the reactor is connected with a wastewater tank through a circulating pump, and the reactor comprises a reactor cylinder; a through hole is formed in the surface of the reactor cylinder, and an electrode channel is formed in the reactor cylinder. According to the multistage electrochemical reactor and method for treating the heavy metal complex and recovering the heavy metal, the heavy metal complex is degraded through the electro-activation oxidizing agent, the heavy metal is synchronously recovered through the cathode, and the heavy metal complex and the heavy metal are synchronously removed; the negative plates and the positive plates can be inserted, taken and replaced at will, the current intensity of each negative plate and each positive plate can be adjusted at will, wastewater containing heavy metal complexes can be treated with the lowest energy consumption and the most flexible method, and the cost for treating the wastewater containing the heavy metal complexes through the electrochemical technology is reduced.

Description

Technical Field

[0001] The invention relates to the technical field of electrochemical water purification, and in particular to a multi-stage electrochemical reactor and method for treating heavy metal complexes to recover heavy metals. Background Art

[0002] There are a lot of heavy metals in electroplating wastewater. When treating electroplating wastewater, a lot of organic substances such as chelating agents, brighteners, stabilizers, etc. will be added. The heavy metals in the water are combined with these organic substances and exist stably in the form of complexes. Unlike conventional heavy metal ions, heavy metal complexes are difficult to remove efficiently through traditional methods such as chemical precipitation, adsorption, and membrane separation. In addition, electroplating wastewater also contains heavy metals with recycling value such as copper, nickel, and chromium, so it is particularly important to study a technology that integrates the degradation of heavy metal complexes and the recovery of heavy metals. Releasing heavy metal ions with the help of advanced oxidation decomposition is the premise and basis for achieving deep purification of wastewater containing heavy metal complexes. Combined with electrochemical technology, efficient removal of heavy metal complexes can be achieved.

[0003] Electrochemical technology has great potential in heavy metal complexes and heavy metal recovery. In electrochemical reactions, heavy metal complexes can be oxidized at the anode, including direct oxidation and indirect oxidation, and then the cathode recovers the powerful heavy metal ions after the heavy metal complex is broken by electroreduction or electrosorption. However, the current electrochemical technology has limited effect on the complete removal of heavy metal complexes. After the heavy metal is recovered, the degradation of organic matter after the complex is broken is not outstanding, and it is difficult to achieve complete degradation of heavy metal complexes. Based on electrochemical technology, a combination of electrochemical technology and advanced oxidation technology has been developed to degrade heavy metal complexes. Electrochemical technology is used to activate oxidants to produce active oxygen species with stronger oxidizing ability, but most of the research now focuses on electrode modification, which may lead to the introduction of new pollutants into wastewater.

[0004] The Chinese invention patent (CN116693007A) "A method for electrochemically activating persulfate to degrade heavy metal complexes coupled with heavy metal recovery" discloses a method for cathode electric field-enhanced persulfate oxidation and complex breaking and metal simultaneous recovery, which belongs to the field of industrial wastewater treatment technology. Specifically, it involves using an electrochemical reactor with anodes and cathodes in the same chamber to activate permonosulfate to produce stronger oxidizing substances, thereby enhancing the removal efficiency of heavy metal complexes, and at the same time, recovering heavy metals through electrodeposition or electrosorption at the cathode. However, it has problems such as long processing time and difficulty in popularization, and the recycling of the reactor needs to be improved.

[0005] At present, there are three problems in treating heavy metal complexes, which are difficult-to-degrade pollutants in electroplating wastewater. First, it is impossible to completely remove heavy metal complexes. For example, adsorption and ion exchange only concentrate or transform heavy metal complexes. Second, it is impossible to directly remove heavy metal complexes and heavy metals at the same time. It is necessary to use secondary precipitation and other technologies to remove heavy metals. For example, the solution after Fenton advanced oxidation treatment is acidic, and a large amount of alkaline substances need to be added to precipitate and remove heavy metal ions. Third, similar electrochemical technologies still have the problems of low oxidation efficiency, high operating costs, and difficulty in expanding applications. Summary of the invention

[0006] The purpose of the present invention is to provide a multi-stage electrochemical reactor and method for treating heavy metal complexes and recovering heavy metals, which can degrade heavy metal complexes by electro-activating oxidants and simultaneously recover heavy metals using cathodes, thereby achieving simultaneous removal of heavy metal complexes and heavy metals; cathode plates and anode plates can be inserted and replaced at will, and the current intensity of each cathode plate and anode plate can be adjusted at will, so as to achieve the treatment of wastewater containing heavy metal complexes with the lowest energy consumption and the most flexible method, thereby reducing the cost of treating heavy metal complex wastewater with electrochemical technology.

[0007] To achieve the above-mentioned purpose, the present invention provides a multi-stage electrochemical reactor for treating heavy metal complexes and recovering heavy metals, comprising a reactor body, a reactor bracket is provided below the reactor body, the reactor body is connected to a wastewater tank through a circulation pump, the reactor body comprises a reactor cylinder, a through hole is provided on the surface of the reactor cylinder, and an electrode groove is provided inside the reactor cylinder.

[0008] Preferably, the through holes are arranged on both sides of the reactor cylinder, the electrode grooves are arranged corresponding to the through holes, and the number of the electrode grooves and the through holes on each side is 10.

[0009] Preferably, a plastic gasket is provided at the electrode groove, and a cathode plate and an anode plate are provided on the plastic gasket.

[0010] Preferably, the cathode plate is carbon felt, and the anode plate is a dimensionally stable DSA electrode.

[0011] Preferably, an upper cover and a lower cover are provided on the upper and lower parts of the reactor cylinder respectively, the reactor cylinder is mechanically clamped by two half barrels through a pipe clamp, and the upper cover and the lower cover are fixedly connected to the reactor cylinder by bolts.

[0012] Preferably, the reactor barrel, the upper cover and the lower cover are all made of nylon, and the reactor bracket is made of stainless steel.

[0013] Preferably, the upper cover and the lower cover are funnel-shaped covers, and the upper cover is provided with an outlet, and the lower cover is provided with an inlet.

[0014] The present invention provides an electrochemical reaction method for treating heavy metal complexes to recover heavy metals, characterized in that: the multi-stage electrochemical reactor for treating heavy metal complexes to recover heavy metals is used, comprising the following steps: Step 1: Pass the conductive metal wire from the outside of the reactor body through the through hole on the reactor cylinder into the electrode channel and connect it to the cathode plate and the anode plate. After the electrochemical reaction device is installed, start the circulation pump; Step 2: Wastewater is pumped out from the wastewater tank through a circulation pump, and then flows into the reactor body from bottom to top. After the liquid enters the reactor body, the DC regulated power supply connected to the metal conductive wire is turned on to power the electrode plate, and the reaction begins. The heavy metal complex is degraded in the reactor body, and the heavy metal after the complex is broken is electrically adsorbed, electrodeposited and electrically reduced on the cathode plate. The treated solution is discharged from the upper outlet of the reactor body and flows back to the wastewater tank, and the wastewater is treated in a reciprocating cycle; Step 3: When the performance of the cathode plate and the anode plate is reduced, turn off the external circulation pump. When the waste liquid treated inside the reactor cylinder is exhausted, open the pipe clamp outside the reactor cylinder, open the reactor cylinder, and replace the electrode plates.

[0015] Therefore, the present invention adopts the above-mentioned multi-stage electrochemical reactor and method for treating heavy metal complexes to recover heavy metals, which has the following beneficial effects: (1) Degrading heavy metal complexes by electro-activating oxidants and simultaneously recovering heavy metals at the cathode to achieve simultaneous removal of heavy metal complexes and heavy metals; (2) The cathode plate and anode plate can be replaced at will, and the current intensity of each cathode plate and anode plate can be adjusted at will, so as to achieve the treatment of wastewater containing heavy metal complexes with the lowest energy consumption and the most flexible method, thereby reducing the cost of electrochemical technology for treating wastewater containing heavy metal complexes; (3) Multi-stage electrochemical reactors can achieve current regulation and thus reduce energy consumption to achieve the purpose of reducing costs. In addition, by regulating the current size, targeted recovery of heavy metals can be achieved to maximize electrode utilization; (4) By circulating the water in the wastewater tank through a circulating pump, the hydraulic retention time in the reactor can be adjusted, thereby improving the oxidation efficiency.

[0016] The technical solution of the present invention is further described in detail below through the accompanying drawings and embodiments. BRIEF DESCRIPTION OF THE DRAWINGS

[0017] Figure 1 2 is a schematic diagram of the structure of a multi-stage electrochemical reactor and method for treating heavy metal complexes and recovering heavy metals according to Embodiment 1 of the present invention; Figure 2It is a perspective structural schematic diagram of a multi-stage electrochemical reactor and method for treating heavy metal complexes and recovering heavy metals according to a first embodiment of the present invention; Figure 3 It is a wastewater flow chart of the first embodiment of the multi-stage electrochemical reactor and method for treating heavy metal complexes and recovering heavy metals according to the present invention; Figure 4 This is a diagram of wastewater treatment in Example 2 of a multi-stage electrochemical reactor and method for treating heavy metal complexes and recovering heavy metals according to the present invention; Figure 5 This is a diagram of wastewater treatment in Example 3 of a multi-stage electrochemical reactor and method for treating heavy metal complexes and recovering heavy metals according to the present invention.

[0018] Reference numerals 1. Reactor cylinder; 2. Electrode groove; 3. Through hole; 4. Upper cover; 5. Lower cover; 6. Reactor bracket. DETAILED DESCRIPTION

[0019] The technical solution of the present invention is further described below through the accompanying drawings and embodiments.

[0020] Unless otherwise defined, the technical terms or scientific terms used in the present invention should be understood by people with ordinary skills in the field to which the present invention belongs. The words "first", "second" and similar words used in the present invention do not indicate any order, quantity or importance, but are only used to distinguish different components. "Include" or "comprise" and similar words mean that the elements or objects appearing before the word include the elements or objects listed after the word and their equivalents, without excluding other elements or objects. "Connect" or "connected" and similar words are not limited to physical or mechanical connections, but may include electrical connections, whether direct or indirect. "Up", "down", "left", "right" and the like are only used to indicate relative positional relationships. When the absolute position of the described object changes, the relative positional relationship may also change accordingly.

[0021] Embodiment 1 like Figure 1 to Figure 2 As shown, the present invention provides a multi-stage electrochemical reactor for treating heavy metal complexes and recovering heavy metals, including a reactor, and the reactor is used to degrade the heavy metal complex. A reactor support 6 is provided below the reactor, and the reactor support 6 is used to support the reactor. The reactor is connected to the wastewater tank through a circulation pump, and the circulation pump is used to pump wastewater into the reactor for electrochemical reaction.

[0022] The reactor includes a reactor cylinder 1, which can provide support for other devices and provide a closed space for electrochemical reactions. The surface of the reactor cylinder 1 is provided with through holes 3, which are arranged on both sides of the reactor cylinder 1, and the through holes 3 are used to pass the conductive metal wire. An electrode groove 2 is provided inside the reactor cylinder 1, and the electrode groove 2 is arranged corresponding to the through holes 3, and the number of the electrode groove 2 and the through holes 3 on each side is 10, and the electrode groove 2 is used to install the electrode plate. A plastic gasket is provided at the electrode groove 2, and the plastic gasket is used to support the cathode plate and the anode plate. A cathode plate and an anode plate are provided on the plastic gasket, and the cathode plate is a carbon felt, and the anode plate is a dimensionally stable DSA electrode. The cathode plate and the anode plate can also be conventional electrodes with water permeability, such as porous carbon materials, graphene-based materials, etc. Electrode plates of different materials can adapt to different oxidants, and the oxidant can be persulfate, or ozone, etc. When in use, the electrode groove 2 and the through hole 3 are sealed with corresponding sealing components to prevent waste liquid from flowing out of the electrode groove 2 and the through hole 3.

[0023] The upper and lower parts of the reactor barrel 1 are respectively provided with an upper cover 4 and a lower cover 5, which cooperate with the reactor barrel 1 to form a sealed environment, and can prevent the leakage of gas generated during the electrochemical reaction. The reactor barrel 1 is mechanically clamped by two half barrels through a pipe clamp, and the upper cover 4 and the lower cover 5 are fixedly connected to the reactor barrel 1 by bolts, and the upper cover 4 and the lower cover 5 are funnel-type covers, the upper cover 4 is provided with an outlet, and the lower cover 5 is provided with an inlet, and the wastewater enters the reactor barrel 1 from the inlet of the lower cover 5, and flows out of the reactor barrel 1 through the outlet on the upper cover 4.

[0024] The reactor body 1, the upper cover 4 and the lower cover 5 are all made of nylon, which has good corrosion resistance and can resist corrosion from a variety of chemical substances and is suitable for treating electrolyte environments containing heavy metal complexes. The reactor bracket 6 is made of stainless steel to maintain structural stability and safety.

[0025] like Figure 3 As shown, the present invention provides an electrochemical reaction method for treating heavy metal complexes to recover heavy metals, characterized in that: the multi-stage electrochemical reactor for treating heavy metal complexes to recover heavy metals is used, comprising the following steps: Step 1: Pass the conductive metal wire from the outside of the reactor through the through hole 3 on the reactor cylinder 1 into the electrode channel 2 and connect it to the cathode plate and the anode plate. After the electrochemical reaction device is installed, start the circulation pump; Step 2: Wastewater is pumped out from the wastewater tank through a circulation pump, and then flows into the reactor from bottom to top. After the liquid enters the reactor, the DC regulated power supply connected to the metal conductive wire is turned on to power the electrode plate, and the reaction begins. The heavy metal complex is degraded in the reactor, and the heavy metal after the complex is broken is electro-adsorbed, electro-deposited and electro-reduced on the cathode plate. The treated solution is discharged from the upper outlet of the reactor and flows back to the wastewater tank, and the wastewater is treated in a reciprocating cycle; Step 3: When the performance of the cathode plate and the anode plate is reduced, turn off the external circulation pump, and when the waste liquid treated inside the reactor cylinder 1 is exhausted, open the pipe clamp outside the reactor cylinder 1, open the reactor cylinder 1, and replace the electrode plates.

[0026] Embodiment 2 The actual wastewater treatment using the electrochemical device includes the following steps: Step 1: Mix actual wastewater with a Cu-EDTA concentration of 0.65 mmol / L with 50 mmol / L anhydrous sodium sulfate and 10 mmol / L potassium persulfate and place them in a wastewater tank.

[0027] Step 2: The wastewater flows from the wastewater tank to the reactor from bottom to top through a circulation pump. When the reactor is filled with liquid, the DC regulated power supply connected to the metal conductive wire is turned on to power the electrode plate, and the reaction begins. The treated solution flows back to the wastewater tank from the upper outlet of the reactor, and the wastewater is treated repeatedly. The specific treatment situation is as follows: Figure 4 As shown in the figure, it can be seen that the electrochemical device has a good removal effect on total organic carbon, total nitrogen, total phosphorus and copper in actual wastewater, and the removal efficiency increases with time.

[0028] Embodiment 3 Step 1: Mix simulated wastewater with a Cu-EDTA concentration of 0.2 mmol / L with 50 mmol / L anhydrous sodium sulfate and 3 mmol / L potassium persulfate and place them in a beaker.

[0029] Step 2: The wastewater flows from the beaker to a small reactor with a similar structure to the large reactor through a circulation pump. After the reactor is filled with liquid, the DC regulated power supply connected to the metal conductive wire is turned on to power the electrode plate, and the reaction begins. The treated solution flows back to the beaker from the upper outlet of the reactor, and the wastewater is treated repeatedly. The specific treatment situation is as follows: Figure 5 As shown in the figure, it can be seen that the copper recovery efficiency of the three-stage reactor is the highest, followed by the two-stage reactor, and then the one-stage reactor. The copper recovery efficiency of the beaker is the lowest, which shows that the treatment effect of the electrochemical device improves with the increase of the reactor level.

[0030] Comparative Example 1 The Chinese invention patent with patent number CN116693007A is used as comparative example 1 to compare with embodiment 3. Figure 5 It can be seen that in the same period of time, the copper recovery efficiency of the multistage reactor is significantly higher than that of the reaction in the beaker. For example, at 60 minutes, the copper recovery efficiency of the three-stage reactor is close to 100%, while the reaction efficiency in the beaker is only about 30%. And the copper recovery efficiency of the multistage reactor increases more significantly over time, especially in the initial stage, the copper recovery efficiency of the first-stage reactor at 10 minutes has exceeded the reaction in the beaker. The copper recovery efficiency curve of the multistage reactor is smoother, indicating that its reaction process is more stable and controllable. The multistage reactor has higher copper recovery efficiency, faster reaction rate and better stability when treating wastewater, showing its advantages in wastewater treatment.

[0031] Therefore, the present invention adopts the above-mentioned multi-stage electrochemical reactor and method for treating heavy metal complexes and recovering heavy metals, degrades heavy metal complexes by electro-activated oxidants, and uses cathodes to simultaneously recover heavy metals, thereby achieving simultaneous removal of heavy metal complexes and heavy metals; the cathode plates and anode plates can be inserted and replaced at will, and the current intensity of each cathode plate and anode plate can be adjusted at will, thereby achieving the treatment of wastewater containing heavy metal complexes with the lowest energy consumption and the most flexible method, thereby reducing the cost of treating heavy metal complex wastewater with electrochemical technology.

[0032] Finally, it should be noted that the above embodiments are only used to illustrate the technical solution of the present invention rather than to limit it. Although the present invention has been described in detail with reference to the preferred embodiments, those skilled in the art should understand that they can still modify or replace the technical solution of the present invention with equivalents, and these modifications or equivalent replacements cannot cause the modified technical solution to deviate from the spirit and scope of the technical solution of the present invention.

Claims

1. A multi-stage electrochemical reactor for treating heavy metal complexes to recover heavy metals, characterized in that: It comprises a reactor body, a reactor bracket is arranged below the reactor body, the reactor body is connected to a wastewater tank through a circulation pump, the reactor body comprises a reactor cylinder, a through hole is arranged on the surface of the reactor cylinder, and an electrode channel is arranged inside the reactor cylinder.

2. The multi-stage electrochemical reactor for treating heavy metal complexes and recovering heavy metals according to claim 1, characterized in that: The through holes are arranged on both sides of the reactor cylinder, the electrode grooves are arranged corresponding to the through holes, and the number of the electrode grooves and the through holes on each side is 10.

3. The multi-stage electrochemical reactor for treating heavy metal complexes and recovering heavy metals according to claim 2, characterized in that: A plastic gasket is provided at the electrode groove, and a cathode plate and an anode plate are provided on the plastic gasket.

4. The multi-stage electrochemical reactor for treating heavy metal complexes and recovering heavy metals according to claim 3, characterized in that: The cathode plate is carbon felt, and the anode plate is a dimensionally stable DSA electrode.

5. The multi-stage electrochemical reactor for treating heavy metal complexes and recovering heavy metals according to claim 4, characterized in that: An upper cover and a lower cover are respectively provided on the upper and lower parts of the reactor cylinder. The reactor cylinder is mechanically clamped by two half barrels through a pipe clamp. The upper cover and the lower cover are fixedly connected to the reactor cylinder through bolts.

6. The multi-stage electrochemical reactor for treating heavy metal complexes and recovering heavy metals according to claim 5, characterized in that: The reactor cylinder, the upper cover and the lower cover are all made of nylon, and the reactor bracket is made of stainless steel.

7. The multi-stage electrochemical reactor for treating heavy metal complexes and recovering heavy metals according to claim 6, characterized in that: The upper cover and the lower cover are funnel-shaped covers, and the upper cover is provided with an outlet, and the lower cover is provided with an inlet.

8. A multi-stage electrochemical reaction method for treating heavy metal complexes to recover heavy metals, characterized in that: The multi-stage electrochemical reactor for recovering heavy metals from heavy metal complexes as claimed in claim 7 comprises the following steps: Step 1: Pass the conductive metal wire from the outside of the reactor body through the through hole on the reactor cylinder into the electrode channel and connect it to the cathode plate and the anode plate. After the electrochemical reaction device is installed, start the circulation pump; Step 2: Wastewater is pumped out from the wastewater tank through a circulation pump, and then flows into the reactor body from bottom to top. After the liquid enters the reactor body, the DC regulated power supply connected to the metal conductive wire is turned on to power the electrode plate, and the reaction begins. The heavy metal complex is degraded in the reactor body, and the heavy metal after the complex is broken is electrically adsorbed, electrodeposited and electrically reduced on the cathode plate. The treated solution is discharged from the upper outlet of the reactor body and flows back to the wastewater tank, and the wastewater is treated in a reciprocating cycle; Step 3: When the performance of the cathode plate and the anode plate is reduced, turn off the external circulation pump. When the waste liquid treated inside the reactor cylinder is exhausted, open the pipe clamp outside the reactor cylinder, open the reactor cylinder, and replace the electrode plates.

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