Membrane-free single-tank water electrolysis hydrogen production-electroplating wastewater enrichment coupling device and method

Abstract

The invention belongs to the technical field of industrial wastewater purification, and discloses a membrane-free single-tank water electrolysis hydrogen production-electroplating wastewater enrichment coupling method and device, and the method comprises the following steps: injecting a neutral electroplating wastewater mixed solution into a membrane-free single tank; discharging air in the membrane-free single tank, and heating the neutral electroplating wastewater mixed solution to a preset temperature; direct current is firstly introduced into the heated neutral electroplating wastewater mixed solution, so that metal ions in the neutral electroplating wastewater mixed solution migrate to the hydrogen evolution electrode, then the direct current is converted into pulse current, so that the metal ions deposit on the hydrogen evolution electrode, and hydrogen precipitated on the hydrogen evolution electrode is continuously collected; closing the current, taking out the hydrogen evolution electrode and collecting metal ions on the hydrogen evolution electrode; and adding an oxygen evolution catalyst into the membrane-free single tank, starting the magnetic rotor to carry out oxygen evolution reaction, and taking out the oxygen evolution catalyst until bromate in the neutral electroplating wastewater mixed solution is completely reduced. According to the invention, the preparation of high-purity hydrogen and oxygen and the enrichment of metal ions can be realized.

Description

Technical Field

[0001] The present application belongs to the technical field of industrial wastewater purification, and more specifically, relates to a membraneless single-tank water electrolysis hydrogen production-electroplating wastewater enrichment coupling device and method. Background Art

[0002] The electroplating industry is one of my country's pillar industries. At the same time, the amount of electroplating wastewater generated has increased dramatically. It contains a variety of heavy metals such as Cr, Ni, Cu, Zn, Pb, and Cd. If the secondary treatment is used to reduce the volume and amount of electroplating sludge, the treatment cost will increase and there will still be problems in subsequent treatment. There is a method in the existing technology to degrade wastewater by using electrolysis of water to produce hydrogen.

[0003] However, the traditional method of hydrogen production by water electrolysis mainly utilizes the hydrogen evolution reaction (HER) at the cathode and the oxygen evolution reaction (OER) at the anode. The rate and energy consumption of hydrogen production are jointly limited by the kinetic process of HER and OER, overpotential and membrane resistance. The use of catalysts improves the kinetic process and reduces the overpotential of the reaction. However, the following problems still exist in the production of hydrogen by water electrolysis: (1) In terms of cost, in order to avoid the problem of hydrogen and oxygen mixing, ion exchange membranes are indispensable, and ion exchange membranes are expensive, which increases the cost of hydrogen production; (2) In terms of catalysts, some high-efficiency catalysts used to improve the kinetic process of HER and OER rely on expensive and scarce precious metals, further increasing the cost of the reaction; (3) In terms of performance, ion exchange membranes increase the internal resistance of the system and increase energy consumption. Proton exchange membranes work in an acidic environment, and their chemical stability and proton conductivity will be affected under long-term high current density operation; although anion exchange membranes have cost advantages, it is difficult to balance ionic conductivity and dimensional stability, which limits the increase in current density and hydrogen production efficiency. In short, due to the poor stability of the catalyst, whether it is the resource scarcity and cost issues of precious metal catalysts at high current density, or the stability issues of non-precious metal catalysts, they cannot meet the needs of long-term, large-scale industrial applications. In addition, in terms of system operation, there is also the problem of difficult power matching. The traditional water electrolysis process requires stable power input to ensure the balance of H2 and O2 yields, thereby reducing the pressure difference on both sides of the membrane. However, OER has slower kinetic characteristics than HER. When the input power changes, the response rates of the two are different, which will cause the instantaneous pressure difference on both sides of the membrane to increase, and there is a risk of membrane damage and gas mixing. The active oxygen produced by the combined action of H2, O2 and the water electrolysis catalyst will degrade the ion exchange membrane, reduce the service life of the membrane, increase maintenance costs and replacement frequency. Summary of the Invention

[0004] In response to the defects of the existing technology, the purpose of this application is to provide a membraneless single-tank water electrolysis hydrogen production-electroplating wastewater enrichment coupling method and device, aiming to solve the problems of low efficiency of traditional water electrolysis hydrogen production methods in degrading electroplating wastewater and difficulty in efficiently enriching and extracting metal ions in electroplating wastewater.

[0005] To achieve the above objectives, in a first aspect, the present application provides a membraneless single-tank water electrolysis hydrogen production-electroplating wastewater enrichment coupling method, comprising: S1 injects a mixed solution of neutral electroplating wastewater into a membraneless single tank, wherein the membraneless single tank is provided with a hydrogen evolution electrode, a bromine evolution electrode and a magnetic stirring unit; S2 discharges the air in the membraneless single tank and heats the neutral electroplating wastewater mixed solution to a preset temperature; S3: firstly passing direct current into the heated neutral electroplating wastewater mixed solution to cause the metal ions in the neutral electroplating wastewater mixed solution to migrate to the hydrogen evolution electrode; then converting the direct current into a pulse current to cause the metal ions to deposit on the hydrogen evolution electrode; and continuously collecting H2 deposited on the hydrogen evolution electrode during the power-on process; S4 turns off the current, takes out the hydrogen evolution electrode and acid-leaches the metal ions thereon to remove the residual H2 in the membraneless single tank; S5: adding an oxygen evolution catalyst to the membraneless single tank, turning on the magnetic stirring unit to carry out an oxygen evolution reaction, and removing the oxygen evolution catalyst and discharging the remaining liquid after the bromate in the neutral electroplating wastewater mixed solution is completely reduced; S6: adding a new electroplating wastewater mixed solution into the membrane-free single tank, and repeating steps S2-S5 for the next enrichment.

[0006] Furthermore, before step S1, the pH value of the electroplating wastewater mixed solution is adjusted to neutral using inorganic salts and buffer substances, and the inorganic salt is at least one of sodium iodide, sodium chloride, ferrous cyanide, and a mixed solution of potassium sulfate and ferric sulfate.

[0007] Furthermore, the buffer substance is at least one of boric acid, potassium dichromate and polyethylene glycol.

[0008] Furthermore, the concentration of the boric acid is 0.1 mol / L to 1.0 mol / L, the concentration of the potassium dichromate is 0.1 mmol / L to 0.5 mmol / L, and the concentration of the polyethylene glycol is 1 mg / L to 100 mg / L.

[0009] Furthermore, in step S3, the DC current is applied for a period of 0.5 h to 2 h, and the DC current is 100 mA / cm 2~ 300mA / cm 2 The pulse current is a periodic commutation pulse current, the duration of the periodic commutation pulse current is 0.5h~4h, and its forward current is 100mA / cm 2~ 200mA / cm 2 , each time lasting 10s~20s, the reverse current is 30mA / cm2 ~70mA / cm 2 , each time lasting 2s~4s, and the cycle frequency of the forward current and the reverse current is 3Hz.

[0010] Furthermore, in step S3, the duration of the periodic commutation pulse current is 2h~3h.

[0011] Furthermore, in step S5, the rotation speed of the magnetic stirring unit is 400 r / min to 500 r / min.

[0012] Furthermore, in step S4, the hydrogen evolution electrode is subjected to ultrasonic vibration treatment in an acidic solution for a treatment time of 20 min to 30 min.

[0013] According to the second aspect of the present application, the present application provides a device for realizing the aforementioned membraneless single-tank electrolysis water hydrogen production-electroplating wastewater enrichment coupling method, comprising: a membraneless single tank, a hydrogen evolution electrode, a bromine evolution electrode, a lifting and clamping unit, a heating unit and a magnetic stirring unit, wherein: the membraneless single tank is a box with a cover, and the hydrogen evolution electrode and the bromine evolution electrode are symmetrically arranged in the middle of the membraneless single tank; the magnetic stirring unit is arranged at the bottom of the membraneless single tank, and is located in the lower middle area of ​​the hydrogen evolution electrode and the bromine evolution electrode; the lifting and clamping unit is arranged on the wall of the membraneless single tank, and includes a clamping end, and the clamping end is used to clamp the oxygen evolution catalyst and lift it up and down between the hydrogen evolution electrode and the bromine evolution electrode; the heating unit is arranged in the membraneless single tank.

[0014] Furthermore, the top cover of the membraneless single tank is provided with an oxygen outlet and a hydrogen outlet, the upper part of the side wall is provided with an exhaust port and a liquid inlet, and the lower part of the side wall is provided with a residual liquid outlet.

[0015] It can be understood that the beneficial effects of the second aspect mentioned above can be found in the relevant description of the first aspect mentioned above, and will not be repeated here.

[0016] In general, the above technical solutions conceived by this application have the following beneficial effects compared with the existing technologies: (1) This application utilizes the hydrogen evolution and oxygen evolution reaction of water electrolysis to enrich metal ions in electroplating wastewater. While achieving metal ion enrichment, it also realizes the extraction of metal substances by cleaning the hydrogen evolution electrode on which metal ions are deposited. This not only reduces the difficulty of electroplating wastewater treatment, but also obtains metal by-products with high added value.

[0017] (2) This application uses an electrochemical-chemical two-step method to decompose water, so that the hydrogen and oxygen evolution reactions proceed in sequence in the same space without the need for ion exchange membrane isolation; the oxidation reaction of oxygen released by the catalysis during the chemical reaction (O2 is produced, and bromate is reduced to Br -The hydrogen evolution reaction at the cathode and the hydrogen evolution reaction at the cathode are separated in time, resulting in higher-purity hydrogen or oxygen in both stages, avoiding contamination by hydrogen and oxygen. Furthermore, the hydrogen and oxygen evolution reactions proceed sequentially in stages, eliminating the need for any diaphragms within the single electrolysis cell, significantly reducing energy consumption. The oxidation reaction that catalyzes oxygen evolution also requires no electricity, further reducing energy consumption.

[0018] (3) During the process of hydrogen production by electrolysis of water, the neutral / alkaline industrial electroplating wastewater is effectively neutralized with the boric acid and potassium dichromate added to the solution, so that the solution is better controlled in a neutral environment and efficient electrolytic hydrogen evolution is achieved; during the DC power-on process, the metal ions migrate to the cathode, and then the metal is deposited on the cathode electrode by a pulsed current. After the electrolysis is completed, the hydrogen evolution electrode is enriched by ultrasonic acid leaching. The entire treatment process is efficient and simple, and no waste liquid is generated or the environment is polluted; the cathode electrode acid washing and the catalytic oxygen evolution in the electrolysis box can be carried out simultaneously, maximizing the treatment efficiency of each batch of wastewater. BRIEF DESCRIPTION OF THE DRAWINGS

[0019] Figure 1 This is a flow chart of the membraneless single-tank water electrolysis hydrogen production and electroplating wastewater enrichment coupling method provided in an embodiment of the present application; Figure 2 Schematic diagram of the SEM spectrum of activated carbon supported on ruthenium dioxide provided in the examples of the present application; Figure 3 Schematic diagram of the SEM spectrum of carbon cloth loaded with ruthenium dioxide provided in the embodiment of the present application; Figure 4 This is a structural schematic diagram of the membraneless single-tank water electrolysis hydrogen production and electroplating wastewater enrichment coupling device provided in an embodiment of the present application.

[0020] Throughout the drawings, the same reference numerals are used to denote the same elements or structures, wherein: 1-Oxygen outlet; 2-Hydrogen outlet; 3-Exhaust port; 4-Liquid inlet; 5-Hydrogen evolution electrode; 6-Bromine evolution electrode; 7-Oxygen evolution catalyst; 8-Lifting and clamping unit; 9-Heating unit; 10-Residual liquid outlet; 11-Magnetic stirring unit; 12-Membraneless single tank; I-Position of the lifting and clamping unit during hydrogen evolution reaction; II-Position of the lifting and clamping unit during oxygen evolution reaction. DETAILED DESCRIPTION

[0021] In order to make the purpose, technical solutions and advantages of this application more clear, the following further describes this application in detail with reference to the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are only used to explain this application and are not intended to limit this application.

[0022] The term "and / or" as used herein describes an association between related objects, indicating that three possible relationships exist. For example, "A and / or B" can represent: A exists alone, A and B exist simultaneously, or B exists alone. The symbol " / " as used herein indicates that the related objects are in an "or" relationship, for example, A / B means either A or B.

[0023] The terms "first" and "second" in this specification and claims are used to distinguish different objects rather than to describe a specific order of objects. For example, "first response message" and "second response message" are used to distinguish different response messages rather than to describe a specific order of response messages.

[0024] In the embodiments of this application, words such as "exemplary" or "for example" are used to indicate examples, illustrations, or descriptions. Any embodiment or design described as "exemplary" or "for example" in the embodiments of this application should not be interpreted as being preferred or advantageous over other embodiments or designs. Rather, the use of words such as "exemplary" or "for example" is intended to present the relevant concepts in a concrete manner.

[0025] In the description of the embodiments of the present application, unless otherwise specified, "multiple" means two or more, for example, multiple processing units means two or more processing units, etc.; multiple elements means two or more elements, etc.

[0026] The embodiments of the present application are described below in conjunction with the drawings in the embodiments of the present application.

[0027] Example 1 The present embodiment provides a membraneless single tank water electrolysis hydrogen production - electroplating wastewater enrichment coupling method which is carried out in stages in a chronological order in a membraneless single tank. The membraneless single tank is a box-type container with a cover. Specifically, Figure 1 As shown, the method includes: S1 uses inorganic salts and buffer substances to adjust the pH value of the electroplating wastewater mixed solution to neutral; inject the neutral electroplating wastewater mixed solution into a membraneless single tank, which is equipped with a hydrogen evolution electrode 5, a bromine evolution electrode 6 and a magnetic stirring unit 11; S2 exhausts the air in the membraneless single tank and heats the neutral electroplating wastewater mixed solution to a preset temperature; S3 first passes direct current into the heated neutral electroplating wastewater mixed solution to make the metal ions in the neutral electroplating wastewater mixed solution migrate to the hydrogen evolution electrode; then converts the direct current into a pulse current to make the metal ions deposit on the hydrogen evolution electrode; during the power-on process, H2 deposited on the hydrogen evolution electrode is continuously collected; S4 turns off the current, takes out the hydrogen evolution electrode and enriches the metal ions on it by acid leaching; removes the residual H2 in the membraneless single tank; S5: adding an oxygen evolution catalyst to the membraneless single tank, turning on the magnetic stirring unit 11 to carry out an oxygen evolution reaction, and carrying out the oxygen evolution reaction until the bromate in the neutral electroplating wastewater mixed solution is completely reduced, then removing the oxygen evolution catalyst and draining the remaining liquid after the reaction; S6 adds new electroplating wastewater mixed solution into the membraneless single tank and repeats steps S2-S5 for the next enrichment.

[0028] Before step S1, an oxygen evolution catalyst is prepared in advance. The oxygen evolution catalyst can be a ruthenium-based, metal-based, or perovskite-based catalyst. This embodiment provides the preparation and performance of block and sheet oxygen evolution catalysts, including two preparation methods of oxygen evolution catalysts.

[0029] The preparation method of the activated carbon-supported ruthenium dioxide oxygen evolution catalyst is as follows: weigh 5g of porous activated carbon, dissolve 12mg of ruthenium trichloride in 15mL of deionized water, completely immerse the porous activated carbon in the ruthenium trichloride aqueous solution, and let it stand for 48 hours. After 48 hours, all the materials are transferred to a reactor and subjected to a thermal reaction in 180℃ water for at least 8 hours. After the hydrothermal reaction is completed, the reactor is removed and filtered to obtain solid porous activated carbon. The solid porous activated carbon is then rinsed repeatedly with deionized water for more than 5 times to remove residual chloride ions. The solid porous activated carbon is transferred to a vacuum drying oven at 80℃ and dried for 12 hours to obtain the activated carbon-supported ruthenium dioxide oxygen evolution catalyst.

[0030] The preparation method of the carbon cloth-supported ruthenium dioxide oxygen evolution catalyst is as follows: 12 mg of ruthenium trichloride is dissolved in 15 mL of deionized water, and then two 2 cm*2 cm pieces of acid-washed carbon cloth are added and completely immersed in the ruthenium trichloride aqueous solution and allowed to stand for 48 hours. After 48 hours, all the materials are transferred to a reactor and hydrothermally reacted at 180°C for 8 hours. After the hydrothermal reaction is completed, the reactor is removed, the carbon cloth is removed, and it is repeatedly rinsed with deionized water 5 times or more to wash away residual chloride ions. The carbon cloth is transferred to a vacuum drying oven at 80°C and dried for 12 hours. After that, it is taken out and placed in a muffle furnace. The temperature is increased by 5°C per minute to 350°C and calcined for 2 hours, and then cooled to room temperature to obtain the carbon cloth-supported ruthenium dioxide oxygen evolution catalyst.

[0031] like Figure 2 and Figure 3 The figures show schematic diagrams of the SEM images of the two catalysts prepared above, namely activated carbon-supported ruthenium dioxide and carbon cloth-supported ruthenium dioxide. The inventors found that the catalytic effect of the activated carbon-supported ruthenium dioxide oxygen evolution catalyst is better than that of the carbon cloth-supported ruthenium dioxide oxygen evolution catalyst because the porous structure of the activated carbon provides more active sites for the catalyst.

[0032] The electroplating wastewater in the above step S1 is industrial electroplating wastewater simulated by mixing with reagents, wherein Fe 2+ 、Cu 2+ 、Ni 2+and Zn 2+ The concentration was 0.5 mol / L and the initial pH was 9.

[0033] In step S1, a mixed solution of electroplating wastewater is first injected into the tank body. The hydrogen evolution electrode 5 in the tank body serves as the cathode and the bromine evolution electrode 6 serves as the anode to form a dual-electrode system. The volume of the solution in the tank body is about 4 / 5 of the total volume of the tank body. Initially, no oxygen evolution catalyst is placed in the tank.

[0034] Specifically, the pH value of the electroplating wastewater mixed solution is adjusted to neutral using inorganic salts and buffer substances. The inorganic salt can be at least one of sodium iodide, sodium chloride, ferrous cyanide, and a mixture of potassium sulfate and ferric sulfate, such as sodium iodide, or a mixture of sodium iodide and sodium chloride, or a mixture of sodium iodide, sodium chloride and ferrous cyanide, or a mixture of sodium iodide, sodium chloride, ferrous cyanide, potassium sulfate and ferric sulfate.

[0035] The aforementioned buffer substance is at least one of boric acid, potassium dichromate and polyethylene glycol. The concentration of the boric acid is 0.1 mol / L to 1.0 mol / L, such as 0.1 mol / L, 0.2 mol / L, 0.3 mol / L, 0.4 mol / L, 0.5 mol / L, 0.6 mol / L, 0.7 mol / L, 0.8 mol / L, 0.9 mol / L or 1.0 mol / L; the concentration of potassium dichromate is 0.1 mmol / L to 0.5 mmol / L, such as 0.1 mmol / L, 0.2 mmol / L, 0.3 mmol / L, 0.4 mmol / L or 0.5 mmol / L; the concentration of polyethylene glycol is 1 mg / L to 100 mg / L, such as 1 mg / L, 10 mg / L, 20 mg / L, 30 mg / L, 40 mg / L, 50 mg / L, 60 mg / L, 70 mg / L, 80 mg / L, 90 mg / L or 100 mg / L.

[0036] The electroplating wastewater solution in this embodiment contains 1 mol / L to 3 mol / L sodium bromide, 0.7 mol / L boric acid, 0.5 mmol / L potassium dichromate, and 50 mg / L polyethylene glycol. The pH value of the solution is adjusted to 6.5, which is close to neutral.

[0037] In the aforementioned step S2, the air in the upper part of the membraneless single tank is discharged, and the neutral electroplating wastewater mixed solution is heated to a preset temperature. Specifically, the solution temperature is raised to at least 60°C.

[0038] In the above step S3, direct current is passed through the preheated neutral electroplating wastewater mixed solution. The duration of the direct current is 0.5h~2h, specifically 2h in this embodiment. The magnitude of the direct current is 100mA / cm 2~ 300mA / cm 2, specifically 200mA / cm in this embodiment 2 The DC power is then converted into a pulse current, which is a periodic commutation pulse current. The duration of the periodic commutation pulse current is 0.5h~4h, and in this embodiment, it can last for 3h. Its forward current is 100mA / cm 2~ 200mA / cm 2 , in this embodiment, it is 200mA / cm², each time lasts 10s~20s, in this embodiment, it lasts 10s; its reverse current is 30mA / cm 2 ~70mA / cm 2 In this embodiment, the current is 50 mA / cm², each time lasting 2 to 4 seconds, and the forward and reverse current cycles are at a frequency of 3 Hz. During the power-on process, the hydrogen produced on the hydrogen evolution electrode side is continuously collected. After the power-on time is over, the power is turned off.

[0039] In the aforementioned step S4, the current is turned off, the hydrogen evolution electrode is removed and the metal ions thereon are cleaned; and a vacuum device, such as a vacuum pump, is used to extract the residual H2 in the membraneless single tank, in preparation for the subsequent oxygen evolution reaction.

[0040] In step S5, an oxygen evolution catalyst composed of multiple flaky oxygen evolution catalysts connected in series is placed in a membraneless single tank between two electrodes. A magnetic stirring unit at the bottom of the membraneless single tank is activated to rotate and stir the remaining electroplating wastewater solution to promote oxygen evolution. The magnetic stirring unit rotates at a speed of 400 to 500 rpm, specifically 400 rpm in this embodiment. Oxygen evolved from the electroplating wastewater solution is continuously collected during the stirring process.

[0041] While the oxygen evolution reaction is in progress, the cathode electrode removed in step S4 is placed in an acidic solution for ultrasonic vibration treatment. Specifically, the hydrogen evolution electrode is placed in a sulfuric acid solution with a pH of 1 for ultrasonic vibration. After 30 minutes, it is taken out and cleaned with deionized water for use in the next round of electroplating wastewater treatment.

[0042] Example 2 The difference between this embodiment and the above embodiment 1 is that the electroplating wastewater is prepared with reagents to simulate industrial wastewater, Fe 2+ 、Cu 2+ 、Ni 2+ and Zn 2+ The concentration is 0.4 mol / L and the pH is 9.

[0043] Example 3 The difference between this embodiment and the above embodiment 1 is that the electroplating wastewater is prepared with reagents to simulate industrial wastewater, Fe 2+ 、Cu 2+ 、Ni 2+ and Zn2+ The concentration is 0.6 mol / L, and the pH is 9.

[0044] Example 4 The difference between this example and the foregoing example 1 is that a direct current of 200 mA / cm2is passed for 3 h in step S2. 2

[0045] Example 5 The difference between this example and the foregoing example 1 is that a direct current of 200 mA / cm2is passed for 1 h in step S2. 2

[0046] Example 6 The difference between this example and the foregoing example 1 is that the pulse current is passed for 4 h in step S2.

[0047] Example 7 The difference between this example and the foregoing example 1 is that the pulse current is passed for 2 h in step S2.

[0048] In each example, the electroplating waste treatment method is cycled 10 times, and the purity of hydrogen gas, the purity of oxygen gas, the Faraday efficiency, and the concentration of metal ions in the electrolytic bath solution are tested, respectively, and the specific data are shown in Table 1 below:

[0049] As can be seen from Table 1 above, the membrane-free single-tank water electrolysis hydrogen production-electroplating wastewater enrichment coupling method provided by the present application can collect high-purity hydrogen gas and oxygen gas, the purity of hydrogen gas is more than 99%, the purity of oxygen gas is more than 98.4%, the Faraday efficiency is more than 94%, and metal ions in the electroplating wastewater solution are also enriched, and a metal byproduct is obtained.

[0050] Example 8 The membrane-free single-tank water electrolysis hydrogen production-electroplating wastewater enrichment coupling device provided by this example can be correspondingly referred to the membrane-free single-tank water electrolysis hydrogen production-electroplating wastewater enrichment coupling method described above, and the specific structure is shown in Figure 4

[0051] ​​​The membraneless single-tank water electrolysis hydrogen production-electroplating wastewater enrichment coupling device includes a membraneless single tank 12, a hydrogen evolution electrode 5, a bromine evolution electrode 6, a lifting clamping unit 8, a heating unit 9 and a magnetic stirring unit 11, wherein: the membraneless single tank 12 is a box with a cover, the hydrogen evolution electrode 5 and the bromine evolution electrode 6 are symmetrically arranged in the middle of the membraneless single tank 12, and can be specifically fixed in the membraneless single tank 12 in a detachable manner; the magnetic stirring unit 11 is fixedly arranged at the bottom of the membraneless single tank 12, and is located in the middle area below the hydrogen evolution electrode 5 and the bromine evolution electrode 6, and an external power supply unit can provide power for it; the lifting clamping unit 8 is arranged on the tank wall of the membraneless single tank 12, and includes a clamping end, which is used to clamp the oxygen evolution catalyst 7, and the lifting clamping unit 8 can drive the oxygen evolution catalyst 7 to move up and down between the hydrogen evolution electrode 5 and the bromine evolution electrode 6; the heating unit 9 is arranged in the membraneless single tank 12, and can be specifically fixed in the membraneless single tank by passing through the cover of the membraneless single tank and being vertically suspended.

[0052] An oxygen outlet 1 and a hydrogen outlet 2 are provided on the top cover of the membraneless single tank 12, and the oxygen outlet 1 and the hydrogen outlet 2 are connected to collection pipes, and the oxygen outlet 1 and the hydrogen outlet 2 are both openable and closable outlets; an openable and closable exhaust port 3 and a liquid inlet 4 are provided on the upper part of the side wall of the membraneless single tank 12, and the exhaust port 3 can be connected to a vacuum pump to extract air, hydrogen or oxygen in the single tank, and the liquid inlet 4 is used to inject the wastewater mixed solution to be electrolyzed; a residual liquid outlet 10 is provided on the lower part of the side wall for discharging the residual liquid after the electrolysis reaction.

[0053] During the hydrogen evolution reaction, the lifting and clamping unit 8 is raised to position I, which moves the oxygen evolution catalyst 7 away from the electroplating wastewater solution (dark green). During the oxygen evolution reaction, the lifting and clamping unit 8 is lowered to position II, which immerses the oxygen evolution catalyst 7 in the electroplating wastewater solution (light green). The lifting and clamping unit 8 can be an electric guide rail, an electric screw, a manual lifting rocker, or a similar lifting device, as long as the lifting and clamping unit 8 can achieve the purpose of driving the oxygen evolution catalyst to move closer to and away from the electroplating wastewater solution in this embodiment.

[0054] It should be understood that expressions such as "include" and "may include" used in this application indicate the existence of the disclosed functions, operations, or constituent elements, and do not limit one or more additional functions, operations, and constituent elements. In this application, terms such as "include" and / or "have" may be interpreted as indicating specific characteristics, numbers, operations, constituent elements, components, or combinations thereof, but may not be interpreted as excluding the existence or possibility of adding one or more other characteristics, numbers, operations, constituent elements, components, or combinations thereof.

[0055] In addition, in this application, the expression "and / or" includes any and all combinations of the associated listed words. For example, the expression "A and / or B" may include A, may include B, or may include both A and B.

[0056] In the description of the embodiments of the present application, it should be noted that, unless otherwise clearly specified and limited, the term "connection" should be understood in a broad sense. For example, "connection" can be a detachable connection or a non-detachable connection; it can be a direct connection or an indirect connection through an intermediate medium. Among them, "fixed connection" means that the two are connected to each other and the relative position relationship after the connection remains unchanged. "Rotational connection" means that the two are connected to each other and can rotate relative to each other after the connection. "Sliding connection" means that the two are connected to each other and can slide relative to each other after the connection. The directional terms mentioned in the embodiments of the present application, such as "top", "bottom", "inside", "outside", "left", "right", etc., are only reference to the directions of the accompanying drawings. Therefore, the directional terms used are for better and clearer explanation and understanding of the embodiments of the present application, rather than indicating or implying that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore cannot be understood as a limitation on the embodiments of the present application.

[0057] In addition, in the embodiments of the present application, the mathematical concepts mentioned include symmetry, equality, parallelism, and perpendicularity. These limitations are all for the current state of the art, rather than being absolutely strict definitions in a mathematical sense. A small amount of deviation is allowed, and it is possible to be approximately symmetric, approximately equal, approximately parallel, or approximately perpendicular. For example, A and B are parallel, which means that A and B are parallel or approximately parallel, and the angle between A and B can be between 0 and 10 degrees. A and B are perpendicular, which means that A and B are perpendicular or approximately perpendicular, and the angle between A and B can be between 80 and 100 degrees.

[0058] The above description is merely a specific embodiment of the present application, but the scope of protection of the present application is not limited thereto. Any changes or substitutions that can be easily conceived by a person skilled in the art within the technical scope disclosed in this application should be included in the scope of protection of this application. Therefore, the scope of protection of this application should be based on the scope of protection of the claims.

Claims

1. A membraneless single-tank water electrolysis hydrogen production-electroplating wastewater enrichment coupling method, characterized in that: include: S1 injects a mixed solution of neutral electroplating wastewater into a membraneless single tank, wherein the membraneless single tank is provided with a hydrogen evolution electrode (5), a bromine evolution electrode (6) and a magnetic stirring unit (11); S2 discharges the air in the membraneless single tank and heats the neutral electroplating wastewater mixed solution to a preset temperature; S3: firstly passing direct current into the heated neutral electroplating wastewater mixed solution, so that the metal ions in the neutral electroplating wastewater mixed solution migrate to the hydrogen evolution electrode (5); then converting the direct current into a pulse current, so that the metal ions are deposited on the hydrogen evolution electrode (5); and continuously collecting H2 deposited on the hydrogen evolution electrode (5) during the power-on process; S4: turning off the current, taking out the hydrogen evolution electrode (5), and enriching the metal ions thereon by acid leaching; removing the residual H2 in the membraneless single tank; S5: adding an oxygen evolution catalyst into the membraneless single tank, turning on the magnetic stirring unit (11) to carry out an oxygen evolution reaction until the bromate in the neutral electroplating wastewater mixed solution is completely reduced, then removing the oxygen evolution catalyst and draining the remaining liquid; S6: adding a new neutral electroplating wastewater mixed solution into the membrane-free single tank, and repeating steps S2-S5 for the next enrichment.

2. The membraneless single-tank water electrolysis hydrogen production-electroplating wastewater enrichment coupling method according to claim 1, characterized in that: Before step S1, the pH value of the electroplating wastewater mixed solution is adjusted to neutral using inorganic salts and buffer substances, and the inorganic salt is at least one of sodium iodide, sodium chloride, ferrous cyanide and a mixed solution of potassium sulfate and ferric sulfate.

3. A membraneless single-tank water electrolysis hydrogen production-electroplating wastewater enrichment coupling method as claimed in claim 2, characterized in that: The buffer substance is at least one of boric acid, potassium dichromate and polyethylene glycol.

4. A membraneless single-tank water electrolysis hydrogen production-electroplating wastewater enrichment coupling method as claimed in claim 3, characterized in that: The concentration of the boric acid is 0.1 mol / L to 1.0 mol / L, the concentration of the potassium dichromate is 0.1 mmol / L to 0.5 mmol / L, and the concentration of the polyethylene glycol is 1 mg / L to 100 mg / L.

5. The membraneless single-tank water electrolysis hydrogen production-electroplating wastewater enrichment coupling method according to claim 1, characterized in that: In step S3, the DC current is applied for a period of 0.5 h to 2 h, and the DC current is 100 mA / cm 2~ 300mA / cm 2 The pulse current is a periodic commutation pulse current, the duration of the periodic commutation pulse current is 0.5h~4h, and the forward current is 100mA / cm 2~ 200mA / cm 2 , each time lasting 10s~20s, the reverse current is 30mA / cm 2 ~70mA / cm 2 , each time lasting 2s~4s, and the cycle frequency of the forward current and the reverse current is 3Hz.

6. A membraneless single-tank water electrolysis hydrogen production-electroplating wastewater enrichment coupling method according to claim 5, characterized in that: In step S3, the duration of the periodic commutation pulse current is 2h~3h.

7. The membraneless single-tank water electrolysis hydrogen production-electroplating wastewater enrichment coupling method according to claim 1, characterized in that: In step S5, the rotation speed of the magnetic stirring unit (11) is 400 r / min to 500 r / min.

8. The membraneless single-tank water electrolysis hydrogen production-electroplating wastewater enrichment coupling method according to claim 1, characterized in that: In step S4, the hydrogen evolution electrode (5) is subjected to ultrasonic vibration treatment in an acidic solution for a treatment time of 20 minutes to 30 minutes.

9. A device for implementing the membraneless single-tank water electrolysis hydrogen production and electroplating wastewater enrichment coupling method as described in any one of claims 1 to 8, characterized in that: include: A membraneless single tank (12), a hydrogen evolution electrode (5), a bromine evolution electrode (6), a lifting clamping unit (8), a heating unit (9) and a magnetic stirring unit (11), wherein: the membraneless single tank (12) is a box with a cover, the hydrogen evolution electrode (5) and the bromine evolution electrode (6) are symmetrically arranged in the middle of the membraneless single tank (12); the magnetic stirring unit (11) is arranged at the bottom of the membraneless single tank (12) and is located in the middle area below the hydrogen evolution electrode (5) and the bromine evolution electrode (6); the lifting clamping unit (8) is arranged on the tank wall of the membraneless single tank (12), and includes a clamping end, and the clamping end is used to clamp the oxygen evolution catalyst and lift it up and down between the hydrogen evolution electrode (5) and the bromine evolution electrode (6); the heating unit (9) is arranged in the membraneless single tank (12).

10. The membraneless single-tank water electrolysis hydrogen production and electroplating wastewater enrichment coupling device according to claim 9, characterized in that: The top cover of the membrane-free single tank (12) is provided with an oxygen outlet (1) and a hydrogen outlet (2), the upper portion of the side wall is provided with an exhaust port (3) and a liquid inlet (4), and the lower portion of the side wall is provided with a residual liquid outlet (10).

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