Device for purifying heavy metals in water by using double-negative-membrane coupled flowing electrode

Abstract

The utility model discloses a device for purifying heavy metals in water by using a double-cathode-membrane coupled flowing electrode. The device comprises a purification tank, and an anode tank (100), a wastewater passing tank and a cathode tank which are sequentially arranged in the purification tank at intervals, wherein a first anion permeable membrane is arranged between the anode tank and the wastewater passing tank; an anode electrode is arranged in the anode tank; the wastewater passing pool is filled with a porous medium; a second anion permeable membrane is arranged between the cathode tank and the wastewater passing tank; a cathode electrode is arranged in the cathode pool; wherein the anode electrode is connected with an anode of a direct-current power supply, and the cathode electrode is connected with a cathode of the direct-current power supply. According to the utility model, an anion solution containing heavy metals is conveyed into the reaction sedimentation tank through the first circulating pump and the first circulating pipe for sedimentation or other innocent treatment; according to the invention, two layers of anion permeable membranes are arranged in the purification tank, so that anion wastewater containing heavy metals is efficiently treated.

Description

Technical Field

[0001] This utility model relates to the field of environmental engineering technology, and in particular to a device for purifying heavy metals in water using a dual anion membrane coupled flow electrode. Background Technology

[0002] Traditional CDI (Capacitive Deionization) consists of two current collectors facilitating electron transport, two fixed electrodes above the current collectors for capacitive ion capture, and a spacer channel between the current collectors through which feed water flows. During the charging process, ions in the feed water are adsorbed by the electrodes. After adsorption, the adsorbed ions are desorbed by short-circuiting the electrodes or changing their polarity, thus regenerating the electrodes. However, the discharge of co-ions limits the deionization capacity of CDI. To address this issue, Lee et al. proposed membrane capacitive deionization (MCDI), which adds cation and anion exchange membranes near the electrodes, fixed on both sides of the channel, to restrict the discharge of co-ions and allow specific ions to pass through the exchange membranes, thereby improving the deionization capacity. However, in a fixed CDI cell, the deionization capacity is limited because the number of electrodes is restricted by the current collectors. Furthermore, traditional CDI and MCDI are also limited by the need for electrode regeneration, cannot operate continuously, and require complex control. To overcome the aforementioned limitations, Jeon et al. first proposed FCDI (Flow-Electrode Capacitive Deionization) in 2013. This method combines an ion exchange membrane with a flowable electrode. Specific electrodes flow through a tortuous channel in the current collector, allowing feed water ions to migrate through the ion exchange membrane to the electrode chamber under the drive of an electric field. This design allows for scaling up processing by increasing the number of electrodes. It also avoids the cumbersome electrode regeneration operations of traditional CDI and MCDI methods. Since its inception, FCDI has seen increasing research, particularly in seawater desalination and pollutant removal, and is considered a promising water treatment method that is more energy-efficient than some traditional processes such as reverse osmosis (RO).

[0003] Based on FCDI, Xu et al. developed a new soil electrochemical remediation technology for removing cadmium from aluminum-containing kaolin. After 19 hours of continuous operation, more than 80% of the cadmium was removed from 200g of cadmium-contaminated kaolin, and the energy consumption was only 22.7kwh / kg. Ya et al. studied the cadmium ion removal capacity of FCDI and explored the effects of applied voltage, flow electrode concentration, flow rate, initial concentration of feed liquid and pH on desalination capacity. Zhou et al.

[38] used FCDI device to effectively concentrate uranium (U(VI)) in radioactive wastewater, and can effectively treat different concentrations (60mg L) -1 -360mg L -1 For wastewater containing U(VI), the removal rate can reach over 99%. Dong et al. studied the removal of Cr(VI) using FCDI, considering the coexistence with different ions, and its relationship with Cl. - In contrast, Cr(VI) is preferentially removed. Jeon et al. studied ion storage and energy recovery during FCDI operation. By measuring changes in the conductivity and current of the effluent, they clarified that ions store energy on the surface of the flowing electrode during FCDI, achieving an energy recovery rate of up to 20% in ICC operation mode. Ma et al. constructed a dual-chamber device to recover energy stored during FCDI discharge. Adding 1.5% carbon nanotubes to the electrode slurry increased the energy recovery rate by 60%, and increasing the salt concentration in the electrode solution reduced energy consumption. When the salt concentration in the electrode solution increased from 0.64 mg / L... -1 Increased to 9.64 mg / L -1 At that time, the energy recovery rate increased from 8% to 9.4%. To achieve efficient and stable operation of magnetic FCDI, Xu et al. further improved the magnetic FCDI technology. This novel magnetic array design allows magnetically modified carbon materials to accumulate on the current collector surface, providing a larger area for electron transfer and shortening the ion adsorption distance. When the voltage is 1.2V, the average desalination rate of the magnetic array FCDI can be maintained at 0.35 μmol / cm³. -2 ·min -1 The charge efficiency can also be maintained above 95%. Gendel et al. modified Jeon's classic FCDI model to develop a dual-module FCDI system, with one module for brine concentration and the other for brine dilution, achieving a desalination rate of over 99% and a recovery rate of up to 90%. Mo Hengliang et al. coupled FCDI with electrodialysis (ED) for desalination research, using the FCDI system for desalination and ED to enhance the regeneration of the flow electrode; the coupled system achieved a desalination rate of 95%. Lim et al. coupled photoelectrochemical processes with FCDI to desalinate organic wastewater, achieving high removal efficiency for organic compounds such as bisphenol A and benzoic acid.

[0004] Flow-electrode capacitive deionization (FCDI), a technology that has gained increasing attention in recent years, possesses characteristics such as low energy consumption, high efficiency, and no secondary pollution, demonstrating its application potential in the remediation of arsenic-containing groundwater. However, the concentration polarization that occurs when the limiting current density is reached makes long-term operation of FCDI difficult. This problem has been a bottleneck hindering its practical application for the past few years and is a common issue faced by electrochemical methods in soil and groundwater remediation. Utilizing wastewater to drive FCDI with a pool-mediated overcurrent can alleviate the inhibitory effect of concentration polarization, thereby continuously and stably driving the separation of valuable substances and improving the removal efficiency of pollutants, potentially overcoming the bottleneck of FCDI's inability to operate for extended periods.

[0005] Existing studies have largely employed a combination of anion exchange membrane and cation exchange membrane, while others have used only a single anion exchange membrane to treat arsenic-containing groundwater; however, the treatment efficiency for wastewater or micro-wastewater containing heavy metals still needs improvement. Utility Model Content

[0006] The purpose of this invention is to provide a device for purifying heavy metals in water using a dual anion membrane coupled with a flowing electrode, solving the problems of heavy metal purification and removal of valuable substances (conductive substances) in conventional drinking water treatment, advanced industrial wastewater treatment, advanced acidic mine wastewater treatment, electronic industry wastewater treatment, and various water sources.

[0007] To solve the above-mentioned technical problems, the present invention adopts the following technical solution:

[0008] This utility model provides a device for purifying heavy metals in water using a dual anion membrane coupled flow electrode, comprising a purification tank, an anode tank, a wastewater passage tank, and a cathode tank arranged sequentially and at intervals within the purification tank;

[0009] A first anion permeable membrane is provided between the anode tank and the wastewater passage tank; an anode electrode is provided inside the anode tank;

[0010] The wastewater flows through a pool filled with a porous medium.

[0011] A second anion permeable membrane is provided between the cathode tank and the wastewater passage tank; a cathode electrode is provided inside the cathode tank;

[0012] The anode electrode is connected to the anode of the DC power supply, and the cathode electrode is connected to the cathode of the DC power supply.

[0013] Furthermore, an inlet is provided at one end of the anode pool, and an outlet is provided at the other end; wherein the outlet of the anode pool is connected to a reaction sedimentation tank through a first circulation pipe, and the upper clear liquid of the reaction sedimentation tank overflows back into the anode pool through the first circulation pipe; wherein a first circulation pump is provided on the first circulation pipe between the outlet of the anode pool and the reaction sedimentation tank.

[0014] Furthermore, the wastewater inlet is provided on one side of the pool, and the wastewater outlet is provided on the other side.

[0015] Furthermore, an inlet is provided at one end of the cathode pool, and an outlet is provided at the other end; wherein the outlet of the cathode pool is connected to an ion compensation box through a second circulation pipe, and the ion compensation box is then connected to the inlet of the cathode pool through another second circulation pipe; wherein a second circulation pump is provided on the second circulation pipe.

[0016] Compared with the prior art, the beneficial technical effects of this utility model are as follows:

[0017] In this invention, under the action of a DC power supply, OH- is generated in the cathode cell. - The wastewater enters the wastewater passage tank through the second anion permeation membrane; the wastewater containing heavy metal anions in the passage tank enters the anode tank; and the anion solution containing heavy metal is transported to the reaction precipitation tank for precipitation or other harmless treatment through the first circulation pump and the first circulation pipe; this application achieves efficient treatment of anion wastewater containing heavy metal by setting two layers of anion permeation membrane in the purification tank. Attached Figure Description

[0018] The present invention will be further described below with reference to the accompanying drawings.

[0019] Figure 1 This is a schematic diagram of the main structure of the device for purifying heavy metals in water using a dual-anion membrane coupled flow electrode according to this utility model;

[0020] Figure 2 This is a schematic diagram of the structure of the device for purifying heavy metals in water using a dual anion membrane coupled flow electrode according to this utility model.

[0021] Explanation of reference numerals in the attached drawings: 100, Anode tank; 101, Anode electrode; 102, First anion permeable membrane; 200, DC power supply; 300, Wastewater passage tank; 301, Wastewater inlet; 302, Wastewater outlet; 400, First circulation pump; 401, First circulation pipe; 402, Reaction sedimentation tank; 500, Cathode tank; 501, Cathode electrode; 502, Second anion permeable membrane; 600, Second circulation pump; 601, Second circulation pipe; 602, Ion compensation box. Detailed Implementation

[0022] This embodiment discloses a device for purifying heavy metals in water using a dual-anion membrane coupled flow electrode, comprising a purification tank, an anode tank 100, a wastewater passage tank 300, and a cathode tank 500 sequentially spaced within the purification tank via ion-permeable membranes; wherein a first anion-permeable membrane 102 is installed between the anode tank 100 and the wastewater passage tank 300; an anode electrode 101 is installed in the anode tank 100; the wastewater passage tank 300 is filled with a porous medium; a second anion-permeable membrane 502 is installed between the cathode tank 500 and the wastewater passage tank 300; and a cathode electrode 501 is installed in the cathode tank 500; wherein the anode electrode 101 is connected to the anode of a DC power supply 200, and the cathode electrode 501 is connected to the cathode of the DC power supply 200.

[0023] In this embodiment, the porous medium can be medium sand of quartz sand or zeolite.

[0024] In this embodiment, an inlet is provided at one end of the anode pool 100, and an outlet is provided at the other end. The outlet of the anode pool 100 is connected to a reaction sedimentation tank 402 through a first circulation pipe 401. The supernatant of the reaction sedimentation tank 402 overflows back into the anode pool 100 through the first circulation pipe 401. A first circulation pump 400 is installed on the first circulation pipe 401 between the outlet of the anode pool 100 and the reaction sedimentation tank 402. In specific use, a precipitant for precipitation of heavy metal anions can be added to the reaction sedimentation tank 402 (the specific reagent is selected according to the precipitation reaction requirements).

[0025] In this embodiment, the wastewater is provided with a wastewater inlet 301 on one side of the pool 300 for injecting wastewater containing heavy metal anions, and a wastewater outlet 302 on the other side for discharging the treated wastewater containing heavy metal anions.

[0026] In this embodiment, an inlet is provided at one end of the cathode pool 500, and an outlet is provided at the other end; the outlet of the cathode pool 500 is connected to an ion compensation box 602 through a second circulation pipe 501, and the ion compensation box 602 is then connected to the inlet of the cathode pool 500 through another second circulation pipe 601; a second circulation pump 600 is installed on the second circulation pipe 601 for circulation.

[0027] The working principle of this utility model:

[0028] In this embodiment, the cathode equation in the cathode cell 500 is as follows:

[0029] 4H + +4e -→2H2↑

[0030] 2H2O+2e - →2OH - +H2↑

[0031] In this embodiment, the anode equation in the anode pool 100 is as follows:

[0032] 4OH - -4e - →2H₂O + O₂↑

[0033] 2H2O-4e - →4H + +O2↑+4e -

[0034] like Figure 2 As shown, the arrows indicate the direction of anion movement, where anions containing heavy metal elements in the water first enter the anode pool 100.

[0035] With the additional DC power supply 200 applied, the OH- ions generated in the cathode tank 500 are directed through the second anion permeation membrane 502 into the wastewater passage tank 300; the wastewater passage tank 300 contains anions of heavy metals, such as Pb(OH)2. 3- Pb(OH)4 2- The solution enters the anode pool 100; and through the first circulation pump 400 and the first circulation pipe 401, the anion solution containing heavy metals is transported to the reaction precipitation pool 402 for precipitation or other harmless treatment.

[0036] The above embodiments are merely preferred embodiments of the present invention and are not intended to limit the scope of the present invention. Any modifications and improvements made to the technical solutions of the present invention by those skilled in the art without departing from the spirit of the present invention should fall within the protection scope defined by the claims of the present invention.

Claims

1. A device for purifying heavy metals in water using a dual-anion membrane coupled flow electrode, characterized in that: It includes a purification tank, an anode tank (100) arranged sequentially and at intervals within the purification tank, a wastewater passage tank (300), and a cathode tank (500). A first anion permeable membrane (102) is provided between the anode tank (100) and the wastewater passage tank (300); an anode electrode (101) is provided inside the anode tank (100). The wastewater passage tank (300) is filled with a porous medium; A second anion permeable membrane (502) is provided between the cathode tank (500) and the wastewater passage tank (300); a cathode electrode (501) is provided inside the cathode tank (500). The anode electrode (101) is connected to the anode of the DC power supply (200), and the cathode electrode (501) is connected to the cathode of the DC power supply (200).

2. The apparatus for purifying heavy metals in water using a dual-anion membrane coupled flow electrode according to claim 1, characterized in that: An inlet is provided at one end of the anode pool (100), and a drain outlet is provided at the other end; wherein the drain outlet of the anode pool (100) is connected to a reaction sedimentation tank (402) through a first circulation pipe (401), and the upper clear liquid of the reaction sedimentation tank (402) overflows back into the anode pool (100) through the first circulation pipe (401); A first circulation pump (400) is installed on the first circulation pipe (401) between the drain outlet of the anode pool (100) and the reaction sedimentation pool (402).

3. The apparatus for purifying heavy metals in water using a dual-anion membrane coupled flow electrode according to claim 2, characterized in that: The wastewater is provided with a wastewater inlet (301) on one side of the pool (300) and a wastewater outlet (302) on the other side.

4. The apparatus for purifying heavy metals in water using a dual-anion membrane coupled flow electrode according to claim 3, characterized in that: An inlet is provided at one end of the cathode pool (500), and an outlet is provided at the other end; wherein the outlet of the cathode pool (500) is connected to an ion compensation box (602) through a second circulation pipe (601), and the ion compensation box (602) is then connected to the inlet of the cathode pool (500) through another second circulation pipe (601); wherein a second circulation pump (600) is provided on the second circulation pipe (601).

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