A multifunctional device for metal removal and recovery of nanoparticle products

Abstract

The present invention belongs to the fields of electrochemistry and membrane separation, and proposes a multifunctional device for metal removal and nanoparticle product recovery. The device includes two electrochemistry crystallization zones, two particle membrane separation zones, and an electrochemistry anode reaction zone. For the first time, the compact structure of a screen cathode / insulating spacer / screen anode is used to accelerate the generation rate and diffusion distance of the alkaline region in the crystallization zone, ensuring the environmental conditions for the formation and growth of metal crystal nuclei, and thus strengthening the occurrence of homogeneous nucleation reactions. Moreover, by regulating the electrochemical parameters and controlling the reaction device, the size of the crystal nuclei is matched with the membrane pore size, shortening the metal particle forming time, improving the device flux and reducing the energy consumption; by controlling the alkalinity of the solution, the orderly removal of various metals is achieved and nanoparticle products with uniform size are generated. The device has high heavy metal removal efficiency and high purity of the recovered products, and can also be used in various fields such as wastewater treatment, carbon dioxide recovery, and production of acid and alkali solutions.

Description

Technical Field

[0001] The present invention relates to the fields of electrochemistry and membrane separation, and particularly to a multifunctional device for metal removal and nanoparticle product recovery. Background Art

[0002] Heavy metal pollution is one of the prominent problems in water pollution. The heavy metals in these wastewaters mainly come from industries such as electroplating, metallurgy, battery manufacturing, and chemical production. The types of metal ions include calcium, magnesium, silver, palladium, chromium, iron, manganese, cobalt, mercury, etc. Discharging wastewater containing heavy metals into the environment will affect the ecological cycle, endanger human health, and even affect the development of future generations through genetic means. Currently, there are many treatment methods for wastewater containing heavy metals, mainly chemical methods, physical methods, and biological methods. As the most commonly used technology, the chemical method requires additional dosing of various agents into the water body. This technology will cause secondary pollution of the water body, and with the strict regulation of agent use by the state, the chemical method will be limited in future water treatment applications. The physical method can avoid the disadvantages of chemical agent dosing, but the physical separation process will only produce more harmful concentrated water, and cannot fundamentally achieve the removal and transformation of heavy metals, and has a high investment cost. The biological method has problems such as a long startup period, being greatly affected by water quality conditions, and low productivity.

[0003] Electrochemistry is a green and active technology that can cause redox reactions of metals in a solution by providing clean electrons and decomposing water, and then enrich and remove them from the solution. Currently, most research focuses on improving efficiency. In order to improve the treatment ability of electrochemistry technology, methods such as chemical modification and complex electrode treatment have also been widely studied. However, traditional materials and processes are still used, and there are few combinations of electrochemistry technology with other technologies. Moreover, in actual engineering, not only high-efficiency metal removal performance is required, but also the treatment cost needs to be reduced, and the proper recovery of heavy metal ions needs to be considered. Summary of the Invention

[0004] In order to solve the above problems, the present invention provides a multifunctional device for metal removal and nanoparticle product recovery.

[0005] Technical Solution of the Present Invention:

[0006] A multifunctional device for metal removal and nanoparticle product recovery, comprising an electrocrystallization zone A13, a particle membrane separation zone A14, an electrocrystallization zone B15, a particle membrane separation zone B16, and an electrochemically anodic reaction zone 17, which are connected in sequence; the electrochemically anodic reaction zone 17 is located on one side of the electrocrystallization zone A13, the particle membrane separation zone A14, the electrocrystallization zone B15, and the particle membrane separation zone B16; a water inlet 6 is provided on one side surface of the electrocrystallization zone A13, and an overflow port A12 is provided on the common surface of the other side of the electrocrystallization zone A13 and the particle membrane separation zone A14; a membrane module unit A8 is installed on the common surface of the particle membrane separation zone A14 and the electrocrystallization zone B15; an overflow port B25 is provided on the common surface of the electrocrystallization zone B15 and the particle membrane separation zone B16; a water outlet C20 is provided on the other side surface of the particle membrane separation zone B16; the contact surface between the electrochemically anodic reaction zone 17 and the particle membrane separation zone A14 and the particle membrane separation zone B16 is separated; water outlets A7 and B19 are respectively provided at both ends of the electrochemically anodic reaction zone 17; the electrochemically anodic reaction zone 17 is connected to the particle membrane separation zone B16 through a connecting membrane module unit B26;

[0007] The liquid flows from the electrocrystallization zone A13 to the particle membrane separation zone A14 through the overflow port A12, and then flows to the electrocrystallization zone B15 through the membrane module unit A8; the liquid flows from the electrocrystallization zone B15 to the particle membrane separation zone B16 through the overflow port B25, and then flows out of the device through the water outlet C20 or flows to the electrochemically anodic reaction zone 17 through the membrane module unit B26;

[0008] The electrocrystallization zone A13 includes a reaction zone A and a particle recovery zone A; the reaction zone A is used to separate the electrocrystallization zone A13 and the electrochemically anodic reaction zone 17, and it includes a wire mesh cathode A9, an insulating partition A10, and a wire mesh anode A11, which are closely attached; the particle recovery zone A is located at the bottom of the electrocrystallization zone A13 and is connected to the electrocrystallization zone A13. It is in the shape of an inverted trapezoid without a top surface and includes a particle recovery tank A1 and a backflow prevention plate 2. The two waists of the trapezoid are the backflow prevention plates 2;

[0009] The particle recovery tank A3 in the membrane separation zone is located at the bottom of the particle membrane separation zone A14 and is connected to the particle membrane separation zone A14;

[0010] The electrocrystallization zone B15 includes a reaction zone B and a particle recovery zone B; the reaction zone B is used to separate the electrocrystallization zone B15 and the electrochemically anodic reaction zone 17, and it includes a closely attached wire mesh cathode B27, an insulating partition B28, and a wire mesh anode B29; the particle recovery zone B includes a particle recovery tank B4 and a backflow prevention plate 2, and its structure is the same as that of the particle recovery zone A;

[0011] The particle recovery tank B5 in the membrane separation zone is located at the bottom of the particle membrane separation zone B16 and is connected to the particle membrane separation zone B16.

[0012] The electrochemically crystallized region A13 further includes a gas collection region and an aeration region; the gas collection region is installed on the top surface of the electrochemically crystallized region A13, and it includes a gas collection hood 23 and an exhaust port 24; the aeration region includes an air inlet 21 and an aeration pipe 22.

[0013] The multifunctional device further includes a partition plate 18, which is used to separate the reaction region A and the particle recovery region A of the electrochemically crystallized region A13. A chute is provided on the inner wall surface between the reaction region A and the particle recovery region A; the partition plate 18 is also used to separate the reaction region B and the particle recovery region B of the electrochemically crystallized region B15. A chute is provided on the inner wall surface between the reaction region B and the particle recovery region B.

[0014] The wire mesh cathodes A9 and B27 are made of metal, which can be any one of stainless steel, iron, copper, titanium, etc.; the insulating partition can be any one of ion exchange membranes, nylon partitions, carbon cloth, carbon felt, etc.; when the insulating partition is a nylon partition, carbon cloth or carbon felt, its mesh number ≥ 200 meshes or the pore size range is 0.001 - 40 μm.

[0015] The liquid contains metal ions such as calcium, magnesium, silver, palladium, chromium, iron, manganese, cobalt, mercury, etc., and contains a sufficient amount of bicarbonate ions. The molar ratio of bicarbonate ions to metal is (>2):1.

[0016] The liquid contains metal ions such as calcium, magnesium, silver, palladium, chromium, iron, manganese, cobalt, mercury, etc., and contains a small amount or no bicarbonate ions in the liquid. At this time, carbon dioxide gas with a certain mass needs to be introduced into the air inlet (21). The molar ratio of carbon dioxide gas to metal is (1 - 10):1.

[0017] The membrane module units A8 and B26 are one of metal membranes, organic membranes, and carbon membranes, and the membrane pore size range is 0.001 - 20 μm.

[0018] Compared with the prior art, the beneficial effects of the present invention are as follows:

[0019] (1) For the first time, a compact structure of wire mesh cathode / insulating partition / wire mesh anode is proposed, which accelerates the generation rate and diffusion distance of the alkaline region in the crystallization region, thereby transferring the nucleation position of the metal from the electrode surface (heterogeneous nucleation) to the solution (homogeneous nucleation). While increasing the metal deposition rate, the operating energy consumption is reduced.

[0020] (2) The electrochemical technology and the membrane separation means are effectively combined. The electrochemical technology controls the crystal nucleus size to match the membrane pore size, shortens the metal particle forming time, improves the device flux and further reduces the energy consumption.

[0021] (3) Control the alkalinity of different crystallization regions to achieve the orderly removal of multiple metals. The produced metal nanoparticles have uniform size and high purity, and do not require secondary treatment, facilitating recycling.

[0022] (4) The device has diverse functions. In addition to metal removal and resource recovery of products, it can also be used in various fields such as wastewater treatment, carbon dioxide recovery, and production of acid-base solutions.

[0023] (5) The device has a simple structure, is easy to operate, and is convenient for realizing an automated integrated design. BRIEF DESCRIPTION OF THE DRAWINGS

[0024] Figure 1 It is a schematic structural diagram of a multifunctional device for metal removal and recovery of nanoparticle products.

[0025] Figure 2 It is a top view of a multifunctional device for metal removal and recovery of nanoparticle products.

[0026] Figure 3 It is a scanning electron microscope image of the recovered nano-calcium carbonate particles.

[0027] Figure 4 It is a scanning electron microscope image of the recovered nano-magnesium hydroxide particles.

[0028] In the figure: 1 - Particle recovery tank A; 2 - Anti-backflow plate; 3 - Particle recovery tank A in the membrane separation area; 4 - Particle recovery tank B; 5 - Particle recovery tank B in the membrane separation area; 6 - Water inlet; 7 - Outlet A; 8 - Membrane module unit A; 9 - Wire mesh cathode A; 10 - Insulating partition A; 11 - Wire mesh anode A; 12 - Overflow port A; 13 - Electrochemical crystallization area A; 14 - Particle membrane separation area A; 15 - Electrochemical crystallization area B; 16 - Particle membrane separation area B; 17 - Electrochemical anodic reaction area; 18 - Partition plate; 19 - Outlet B; 20 - Outlet C; 21 - Gas inlet; 22 - Aeration pipe; 23 - Gas collection hood; 24 - Exhaust port; 25 - Overflow port B; 26 - Membrane module unit B; 27 - Wire mesh cathode B, 28 - Insulating partition B, 29 - Wire mesh anode B. DETAILED DESCRIPTION OF THE INVENTION

[0029] To further illustrate the present invention, the present invention will be described in detail below in conjunction with embodiments. However, they should not be construed as limiting the protection scope of the present invention. All other embodiments obtained by those of ordinary skill in the art based on the embodiments of the present invention without creative efforts shall fall within the protection scope of the present invention.

[0030] A multifunctional device for metal removal and nanoparticle product recovery according to the present invention, wherein the electrochemical crystallization zone A13 is weakly alkaline, nanoparticles represented by calcium carbonate are generated in the particle membrane separation zone A14, the electrochemical crystallization zone B15 is strongly alkaline, and nanoparticles represented by magnesium hydroxide are generated in the particle membrane separation zone B15.

[0031] Example 1

[0032] A multifunctional device for metal removal and nanoparticle product recovery according to the present invention is used to treat simulated water containing Ca 2+ , Mg 2+ to achieve the separate removal and resource recovery of calcium and magnesium ions. The total hardness of the simulated water is 500 mg / L (calculated as CaCO3), including a calcium hardness of 300 mg / L, a magnesium hardness of 200 mg / L, an alkalinity of 9 mmol / L, and an inlet water pH value of 8.1.

[0033] Combined with Figure 1 , 2 Describe the specific implementation manner of the present invention. Select a stainless steel wire mesh with a mesh number of 10 as the wire mesh cathode A9 and the wire mesh cathode B27, a nylon separator with a mesh number of 400 as the insulating separator, and a ruthenium-iridium-titanium mesh as the wire mesh anode, and closely fit the three and place them in the electrochemical crystallization zone A13 and the electrochemical crystallization zone B15. Introduce the simulated water into the device from the water inlet 6, and it flows through the electrochemical crystallization zone A13, the particle membrane separation zone A14, the electrochemical crystallization zone B15, and the particle membrane separation zone B16 in sequence and then flows out from the water outlet C20. The membrane module unit A8 and the membrane module unit B26 select an organic membrane with a pore size of 300 nm. Adjust the current density of the wire mesh cathode A9 to 12 mA / cm 2 , and set the hydraulic retention time of the simulated water in the electrochemical crystallization zone A13 to 2.5 minutes. Adjust the current density of the wire mesh cathode B27 to 21 mA / cm 2 , and set the hydraulic retention time of the simulated water in the electrochemical crystallization zone B15 to 2.5 minutes. After the water outlet is stable, test the water quality data of each zone as shown in Table 1. The removal rates of calcium and magnesium hardness in the final effluent solution both reach more than 99%. The energy consumption of the whole process is less than 3 kW·h / kg CaCO3. During the reaction process, close the partition plate 18 to separate the reaction zone A and the particle recovery zone A of the electrochemical crystallization zone A13 and the reaction zone B and the particle recovery zone B of the electrochemical crystallization zone B15, and then recover the calcium deposits from the particle recovery tank A1 and the particle recovery tank A3 in the membrane separation zone. Its main component is CaCO3. It can be seen from the scanning electron microscope Figure 3 that the morphology of CaCO3 is mainly shuttle-shaped, with an average length of 3 μm and an average width of 800 nm. Then recover the magnesium deposits from the particle recovery tank B4 and the particle recovery tank B5 in the membrane separation zone. Its main component is Mg(OH)2. It can be seen from the scanning electron microscope Figure 4It can be seen that the morphology of Mg(OH)2 is mainly a two-dimensional lamellar structure, and the average particle size is 300 nm.

[0034] Table 1. Residual calcium, magnesium hardness and pH value in the solution of each reaction zone.

[0035]

[0036] Example 2

[0037] A multifunctional device for metal removal and nanoparticle product recovery according to the present invention is used to treat simulated water containing Ca 2+ , Mg 2+ to achieve the separate removal and resource recovery of calcium and magnesium ions. The total hardness of the simulated water is 500 mg / L (calculated as CaCO3), among which the calcium hardness is 300 mg / L, the magnesium hardness is 200 mg / L, the alkalinity is 0 mmol / L, and the inlet water pH value is 6.9.

[0038] Combined with Figure 1 , 2 to illustrate the specific implementation manner of the present invention. A stainless steel wire mesh with a mesh number of 10 is selected as the wire mesh cathode A9 and the wire mesh cathode B27, a nylon separator with a mesh number of 400 is selected as the insulating separator, and a ruthenium-iridium-titanium mesh is selected as the wire mesh anode. The three are closely attached and placed in the electrochemical crystallization zone A13 and the electrochemical crystallization zone B15. The simulated water is introduced into the device from the water inlet 6 and flows through the electrochemical crystallization zone A13, the particle membrane separation zone A14, the electrochemical crystallization zone B15 and the particle membrane separation zone B16 in sequence and then flows out from the water outlet C20. The membrane module unit A8 and the membrane module unit B26 select an organic membrane with a pore size of 300 nm. The CO2 gas is introduced from the gas inlet 21, and after being dispersed by the gas distribution pipe 22, it is evenly distributed in the electrochemical crystallization zone A13. The input mass of CO2 is 6 mmol / L / min. The remaining CO2 gas is collected by the gas collection hood 23 and escapes through the exhaust port 24. Then the exhaust port 24 is connected to the gas inlet 21, and the CO2 gas enters the electrochemical crystallization zone A13 again, so that the CO2 gas is fully utilized. The current density of the wire mesh cathode A9 is adjusted to 15 mA / cm 2 , and the hydraulic retention time of the simulated water in the electrochemical crystallization zone A13 is set to 2.5 minutes. The current density of the wire mesh cathode B27 is adjusted to 25 mA / cm 2 , and the hydraulic retention time of the simulated water in the electrochemical crystallization zone B15 is set to 2.5 minutes. After the water outlet is stable, the water quality data of each zone are tested and shown in Table 2. The removal rates of calcium and magnesium hardness in the final outlet solution both reach more than 99%. The energy consumption of the whole process is less than 3.8 kW·h / kg CaCO3. At this time, the utilization rate of the CO2 gas reaches 68%.

[0039] Table 2. CO2 concentration, residual calcium, magnesium hardness, and pH value in the solutions of each reaction zone.

[0040]

[0041] Example 3

[0042] A multifunctional device for metal removal and nanoparticle product recovery according to the present invention is used to treat the actual circulating cooling water of a certain factory to reduce the hardness of the circulating water (Ca 2+ , Mg 2+ ). The total hardness of the actual water is 592 mg / L (calculated as CaCO3), including a calcium hardness of 550 mg / L, a magnesium hardness of 42 mg / L, an alkalinity of 11 mmol / L, and an inlet water pH value of 8.5.

[0043] Combined with Figure 1 , 2 To illustrate the specific implementation manner of the present invention, a stainless steel wire mesh with a mesh number of 10 is selected as the wire mesh cathode 9 and the wire mesh cathode B27, a nylon separator with a mesh number of 400 is selected as the insulating separator, and a ruthenium-iridium-titanium mesh is selected as the wire mesh anode. The three are closely attached and placed in the electrochemical crystallization zone A13 and the electrochemical crystallization zone B15. The simulated water is introduced into the device from the water inlet 6 and flows through the electrochemical crystallization zone A13, the particle membrane separation zone A14, the electrochemical crystallization zone B15, the particle membrane separation zone B16, and the electrochemical anode reaction zone 17 in sequence, and then flows out from the water outlet A7. The membrane module unit A8 and the membrane module unit B26 select an organic membrane with a pore size of 300 nm. The current density of the wire mesh cathode A9 is adjusted to 12 mA / cm 2 , and the hydraulic retention time of the simulated water in the electrochemical crystallization zone A13 is set to 2.5 minutes. The current density of the wire mesh cathode B27 is adjusted to 21 mA / cm 2 , and the hydraulic retention time of the simulated water in the electrochemical crystallization zone B15 is set to 2.5 minutes. After the water outlet is stable, the water quality data of each zone are tested and shown in Table 3. The final removal rate of the total hardness of the effluent is 92.3%. To ensure that the pH of the effluent is less than 9, the actual water after being treated by the particle membrane separation zone B16 enters the electrochemical anode reaction zone 17 for acid-base neutralization, and the final effluent is weakly alkaline with a pH of 8.7. The energy consumption of the whole process is approximately 3.5 kW·h / kg CaCO3.

[0044] Table 3. Residual calcium, magnesium hardness, and pH value in the solutions of each reaction zone.

[0045]

[0046]

Claims

1. A multifunctional device for metal removal and nanoparticle product recovery, characterized in that, The multifunctional device for metal removal and nanoparticle product recovery includes an electrocrystallization zone A (13), a particle membrane separation zone A (14), an electrocrystallization zone B (15), a particle membrane separation zone B (16), and an electrochemically anodic reaction zone (17) that are connected in sequence; the electrochemically anodic reaction zone (17) is located on one side of the electrocrystallization zone A (13), the particle membrane separation zone A (14), the electrocrystallization zone B (15), and the particle membrane separation zone B (16); a water inlet (6) is opened on one side surface of the electrocrystallization zone A (13), and an overflow port A (12) is opened on the common surface of the other side of the electrocrystallization zone A (13) and the particle membrane separation zone A (14); a membrane module unit A (8) is installed on the common surface of the particle membrane separation zone A (14) and the electrocrystallization zone B (15); an overflow port B (25) is opened on the common surface of the electrocrystallization zone B (15) and the particle membrane separation zone B (16); a water outlet C (20) is opened on the other side surface of the particle membrane separation zone B (16); the contact surfaces of the electrochemically anodic reaction zone (17) with the particle membrane separation zone A (14) and the particle membrane separation zone B (16) are separated; water outlet A (7) and water outlet B (19) are respectively arranged at both ends of the electrochemically anodic reaction zone (17); the electrochemically anodic reaction zone (17) is communicated with the particle membrane separation zone B (16) through a connecting membrane module unit B (26); The liquid flows from the electrocrystallization zone A (13) to the particle membrane separation zone A (14) through the overflow port A (12), and then flows to the electrocrystallization zone B (15) through the membrane module unit A (8); the liquid flows from the electrocrystallization zone B (15) to the particle membrane separation zone B (16) through the overflow port B (25), and then flows out of the device through the water outlet C (20) or flows to the electrochemically anodic reaction zone (17) through the membrane module unit B (26); wherein, the liquid includes metal ions and bicarbonate ions; the metal ions are one or more mixtures of calcium, magnesium, silver, palladium, chromium, iron, manganese, cobalt, and mercury; the molar ratio of bicarbonate ions to the metal is greater than >2:1; The electrocrystallization zone A (13) includes a reaction zone A and a particle recovery zone A; the reaction zone A is used to separate the electrocrystallization zone A (13) and the electrochemically anodic reaction zone (17), and it includes a wire mesh cathode A (9), an insulating partition A (10), and a wire mesh anode A (11), which are closely attached; the particle recovery zone A is located at the bottom of the electrocrystallization zone A (13) and is communicated with the electrocrystallization zone A (13). It is in the shape of an inverted trapezoid without a top surface, and the two waists of the trapezoid are anti-backflow plates (2); The particle recovery tank A (3) of the membrane separation zone is located at the bottom of the particle membrane separation zone A (14) and is communicated with the particle membrane separation zone A (14); The electrocrystallization zone B (15) includes a reaction zone B and a particle recovery zone B; the reaction zone B is used to separate the electrocrystallization zone B (15) and the electrochemically anodic reaction zone (17), and it includes a closely attached wire mesh cathode B (27), an insulating partition B (28), and a wire mesh anode B (29); the particle recovery zone B includes a particle recovery tank B (4) and an anti-backflow plate (2), and its structure is the same as that of the particle recovery zone A; The particle recovery tank B(5) in the membrane separation zone is located at the bottom of the particle membrane separation zone B(16) and is communicated with the particle membrane separation zone B(16).

2. The multifunctional device for metal removal and nanoparticle product recovery according to claim 1, wherein The electrochemically crystallized zone A(13) further includes a gas collection zone and an aeration zone; the gas collection zone is installed on the top surface of the electrochemically crystallized zone A(13), and it includes a gas collection hood (23) and an exhaust port (24); the aeration zone includes an air inlet (21) and an air diffuser pipe (22).

3. The multifunctional device for metal removal and nanoparticle product recovery according to claim 1 or 2, characterized in that, The multifunctional device further includes a partition plate (18), which is used to separate the reaction zone A and the particle recovery zone A of the electrochemically crystallized zone A(13), and a chute is provided on the inner wall surface between the reaction zone A and the particle recovery zone A; the partition plate (18) is also used to separate the reaction zone B and the particle recovery zone B of the electrochemically crystallized zone B(15), and a chute is provided on the inner wall surface between the reaction zone B and the particle recovery zone B.

4. The multifunctional device for metal removal and nanoparticle product recovery according to claim 1 or 2, characterized in that, The wire mesh cathodes A(9) and B(27) are made of one of stainless steel, iron, copper, and titanium; the insulating separator is one of an ion exchange membrane, a nylon separator, a carbon cloth, and a carbon felt; when the insulating separator is a nylon separator, a carbon cloth, or a carbon felt, its mesh number ≥ 200 or the pore size range is 0.001 - 40 μm.

5. The multifunctional device for metal removal and nanoparticle product recovery according to claim 3, wherein, The wire mesh cathodes A(9) and B(27) are made of one of stainless steel, iron, copper, and titanium; the insulating separator is one of an ion exchange membrane, a nylon separator, a carbon cloth, and a carbon felt; when the insulating separator is a nylon separator, a carbon cloth, or a carbon felt, its mesh number ≥ 200 or the pore size range is 0.001 - 40 μm.

6. The multifunctional device for metal removal and nanoparticle product recovery according to claim 3, wherein, The membrane module units A(8) and B(26) are made of one of a metal membrane, an organic membrane, and a carbon membrane, and the membrane pore size range is 0.001 - 0.3 μm.

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