Device and method for synchronously treating waste gas and waste liquid in nickel net activation process

Abstract

The invention discloses a waste gas and waste liquid synchronous treatment device and method in a nickel net activation process, and particularly relates to the technical field of waste liquid and waste gas treatment.The device comprises a nickel net activation reactor, a gas drying pipeline, an electrochemical neutralization treatment device and an evaporation recovery device; wherein the electrochemical neutralization treatment device comprises a gas diffusion electrode positive electrode, an acidic liquid reaction chamber, a porous membrane, an alkaline liquid reaction chamber and a gas diffusion electrode negative electrode; oxygen of the positive electrode of the gas diffusion electrode comes from air, and gas of the negative electrode of the gas diffusion electrode comes from waste gas in a nickel net activation process.

Description

Technical Field

[0001] The invention relates to the field of waste liquid and waste gas treatment, and in particular to a waste gas and waste liquid synchronous treatment device and method in a nickel mesh activation process. Background Art

[0002] Hydrogen energy is a clean energy with high energy density. It has the advantages of zero pollution and zero carbon emissions, so it is known as the "ultimate energy of the 21st century". In the context of global green energy transformation, the use of renewable energy to produce hydrogen through electrolysis of water through electrolyzer devices is a green, clean and sustainable way to produce hydrogen. The electrode is a key component in the electrolyzer for hydrogen production by electrolysis of water, and its catalytic performance directly determines the efficiency, energy consumption and cost of hydrogen production. At present, the mainstream water electrolysis technology in my country is roughly divided into four types according to the working principle of the electrolyzer: alkaline electrolyzer (ALK), proton exchange membrane electrolyzer (PEM), anion exchange membrane electrolyzer (AEM) and solid oxide electrolyzer (SOEC). Among them, the alkaline electrolyzer hydrogen production device is easy to scale, and its technology is highly mature and low in cost. Therefore, this technology has achieved large-scale hydrogen production applications at the megawatt level in my country and even in the world. The electrodes for hydrogen production by alkaline electrolysis of water are mainly made of nickel-based materials, because nickel has good high temperature resistance and alkali corrosion resistance, and the cost is relatively low. Nickel-based electrodes usually use pure nickel mesh or nickel foam as a substrate, and are coated with catalysts by processes such as spraying, rolling or chemical plating to improve electrolysis efficiency. The most commonly used catalyst is a nickel-based catalyst represented by Raney nickel. The preparation of the Raney nickel electrode is generally carried out by spraying Raney nickel on a nickel mesh electrode with a certain surface roughness. The spraying process is to heat the nickel-aluminum alloy powder to a molten or semi-molten state through a certain heat source (such as a plasma arc). Under the action of a high-speed airflow, these molten or semi-molten particles will impact the surface of the pretreated nickel mesh. Subsequently, the sprayed nickel mesh needs to be activated with a sodium hydroxide solution to react the aluminum in the Raney nickel, thereby forming a nickel-based electrode with a high specific surface area and excellent catalytic performance. However, in the alkali solution treatment process, waste gas mainly composed of hydrogen and waste liquid with strong alkalinity are often generated. At present, combined with the analysis of existing literature, there is no special treatment technology for the waste gas generated in this process, and most of them are mainly directly discharged. As for alkaline waste liquid, it can be treated by conventional wastewater treatment methods, such as chemical treatment, ion exchange and reverse osmosis.

[0003] Chinese patent CN114122569A, a hydride / air battery for simultaneously treating waste acid and waste alkali and generating electricity, is a patent application previously filed by the inventor, comprising: an air diffusion electrode as a positive electrode, a hydride electrode for pre-storing hydrogen as a negative electrode, and an ion exchange membrane, wherein: the positive and negative electrodes are placed in a waste acid solution and a waste alkali solution respectively and the positive and negative electrodes are connected to an external circuit, and the ion exchange membrane is arranged between the acid and alkali electrolytes as a diaphragm material; when the battery is discharged or the waste acid and alkali are treated, the reaction at the negative electrode is to precipitate hydrogen and react with OH in the waste alkali - The ions undergo an oxidation reaction to generate water and produce electrons; at the same time, the electrons are led out of the external circuit and flow to the positive electrode, so that the oxygen in the air and the H in the waste acid react. + The ions undergo a reduction reaction to generate water. Although the patent also mentions the use of oxygen in the air as an oxidant, the negative electrode of the patent uses a hydride electrode with pre-stored hydrogen, which realizes acid-base electrochemical neutralization during the discharge process, but cannot process hydrogen at the same time. In addition, the hydride electrode is not suitable for large-scale application. This is because the electrochemical treatment of waste alkali by hydride requires a large amount of hydride, which cannot meet the needs of large-scale industrial production. Moreover, if the waste alkali liquid is to be continuously treated, the hydride with pre-stored hydrogen needs to be continuously replenished, which is not only costly, but also complicated to continuously add. However, even if it can be replenished, it is necessary to stop and carry out complex hydrogenation treatment, which is time-consuming, labor-intensive and costly. Therefore, it is necessary to find a negative electrode electrode suitable for continuous treatment of waste alkali liquid and hydrogen and meet the needs of large-scale industrial production. It is an urgent problem to be solved. At the same time, the patent uses an ion exchange membrane, but the ion exchange membrane cannot provide rapid ion transmission, resulting in the inability of the electrochemical neutralization reaction to proceed quickly, because a rapid electrochemical reaction requires a rapid electrode reaction, and also requires an internal circuit that is turned on by rapid ion transmission. Based on this patent, there is an urgent need for a device and method that can simultaneously treat waste gas and waste liquid in the nickel mesh activation process. Summary of the invention

[0004] To this end, the present invention provides a device and method for synchronously treating waste gas and waste liquid in a nickel mesh activation process to solve the problems in the prior art.

[0005] Generally speaking, ion exchange membranes can only allow ions with positive or negative charges to pass through, and the transmission speed is not fast enough. After all, ion exchange membranes are very dense membranes, so it is difficult to complete good neutralization between ion exchange membranes for hydrogen ions and hydroxyl ions involved in acid-base neutralization. The slow transmission of ions between membranes will greatly affect the processing speed of waste gas hydrogen. Therefore, porous membranes have more advantages. That is, porous membranes can achieve rapid ion transmission, so that hydrogen can be processed quickly. At the same time, since the porous membrane is "unlimited", it can also neutralize some acids and bases faster, while ion exchange membranes cannot do so quickly. Ion exchange membranes are mainly for ion exchange, and the wastewater treatment of the present invention is only to neutralize them, so there is no need to use ion exchange membranes. It is only necessary to use a porous membrane with a suitable pore size to ensure that the acid and alkali are not immediately neutralized during the hydrogen treatment process, otherwise the waste gas cannot be treated. When the hydrogen is treated, the acid and alkali can directly meet through the pipeline design of the electrochemical neutralization device to quickly complete the neutralization process. Ion exchange membranes cannot provide fast ion transport, resulting in the inability to quickly process hydrogen, because fast electrochemical reactions require fast electrode reactions and also require an internal circuit that is turned on by fast ion transport. The mention here that the electrode reaction needs to be fast also explains why the present invention needs to use a gas diffusion electrode instead of the hydride solid electrode of the previous patent CN114122569A. Because the hydrogen oxidation reaction that occurs at the gas diffusion electrode is faster. In addition, patent CN114122569A uses a hydride solid electrode with pre-stored hydrogen to achieve discharge neutralization treatment of waste acid and waste alkali, but a hydride solid electrode with good pre-stored hydrogen cannot treat waste hydrogen.

[0006] The focus of the present invention is to utilize the waste alkali produced by the nickel mesh activation process to simultaneously treat the hydrogen produced by the nickel mesh through an electrochemical neutralization reaction. After the hydrogen is treated, the acid and alkali can simply be directly neutralized by flowing through the pipeline. Since the waste alkali is often in excess, after the hydrogen is treated, the acid and alkali can be neutralized as soon as possible. The subsequent next batch of nickel mesh treatment will require newly prepared alkali solution for treatment, and the next batch of waste liquid will be produced. Compared with the inventor's previous patent CN114122569A, the hydride electrode of the prior patent cannot process hydrogen. The hydride electrode is already an electrode "full of hydrogen". The hydrogen will be used to react with the alkali solution. The waste hydrogen generated by the nickel mesh cannot be treated, so the prior device can only neutralize and treat the waste liquid.

[0007] The present invention first directly converts the waste gas mainly composed of hydrogen into water by reacting with hydroxide ions by using a rapid electrochemical neutralization treatment device, and simultaneously neutralizes and treats the alkaline waste liquid mainly composed of sodium hydroxide and sodium aluminate. The specific reaction involved in the neutralization treatment device is: when the electrochemical treatment device is in a high current discharge or short circuit state, after the discharged hydrogen is conducted to the gas diffusion electrode (negative electrode), the hydrogen will undergo an oxidation reaction under alkaline conditions to consume hydroxide ions to generate water; while the counter electrode undergoes a reduction reaction of oxygen from the air on the gas diffusion electrode (positive electrode) to consume hydrogen ions and also generate water; in addition, in addition to electrochemical neutralization, the alkaline waste liquid will also undergo chemical neutralization mainly by diffusion between the porous diaphragms, further accelerating the neutralization treatment of the waste liquid, and can produce high value-added salts accordingly. Subsequently, the neutralized waste liquid is evaporated by low-temperature rotary evaporation to obtain sodium salt, aluminum salt and water. No waste gas or waste liquid is discharged during the treatment process of the present invention, and the waste gas and waste liquid generated during the activation process of the nickel mesh can be continuously treated. The present invention provides a green synchronous treatment technology path for the environmental pollution problem caused by waste gas and waste liquid generated in the nickel mesh activation industrial production, which has practical significance and good application prospects.

[0008] In order to achieve the above object, the present invention provides the following technical solutions:

[0009] According to one aspect of the present invention, a device for simultaneously treating waste gas and waste liquid in a nickel mesh activation process is provided, the device comprising a nickel mesh activation reactor, a gas drying pipeline, an electrochemical neutralization treatment device and an evaporation recovery device; wherein the electrochemical neutralization treatment device comprises a gas diffusion electrode positive electrode, an acidic liquid reaction chamber, a porous membrane, an alkaline liquid reaction chamber and a gas diffusion electrode negative electrode; the oxygen of the gas diffusion electrode positive electrode comes from the air, and the gas of the gas diffusion electrode negative electrode comes from the waste gas in the nickel mesh activation process.

[0010] Furthermore, the gas diffusion electrode positive electrode and the gas diffusion electrode negative electrode are obtained by mixing and grinding the catalyst, conductive carbon black and a binder solution, and then applying the mixture on the surface of a hydrophobic carbon cloth and drying the mixture.

[0011] Further, the catalyst is a platinum-based catalyst, a low-platinum catalyst or a non-platinum catalyst. As an example, a platinum-based catalyst is preferred.

[0012] Furthermore, the mixing ratio of the catalyst, the conductive carbon black and the binder solution is 0.1-40%: 30-85%: 5%-30%.

[0013] Furthermore, the binder is PTFE (polytetrafluoroethylene) or PVDF (polyvinylidene fluoride).

[0014] Furthermore, the thickness of the gas diffusion electrode is 10-100 microns. The thickness mainly depends on the manufacturing process and the equipment to make the electrode long-life stable. It mainly depends on the performance of the electrode, and it only needs to meet the electrode performance.

[0015] Furthermore, the preparation of the gas diffusion electrode further includes placing the electrode in aluminum foil for pressing after it is dried, so as to further prevent the catalyst from peeling off. Preferably, the pressure is 3-18 MPa and the pressing time is 8-30 seconds.

[0016] Furthermore, the pore size of the porous membrane is 0.05-20 micrometers; the membrane thickness is 0.02-1 millimeter.

[0017] Furthermore, the porous membrane is made of one or more of fiber, polytetrafluoroethylene, polyvinylidene fluoride, woven fabric and plastic.

[0018] The porous membrane can be prepared by mixing one or several materials. Plastic can be selected to ensure that it is inert or acid-resistant. Generally, to prepare a porous membrane, you must first choose a method based on the physical properties of the membrane material. For example, if fiber materials are used, it can be simply electrospinning or spunbonding; if plastics are used, it is necessary to use chemical foaming or template methods; and if multiple mixed materials are used, it is necessary to choose a method based on the physical properties of the main materials / components. The choice of materials for porous membranes can further improve the cost-effectiveness after subsequent industrialization.

[0019] Furthermore, the acidic liquid is an inorganic acid and / or an organic acid. The acidic liquid can be a prepared inorganic acid and / or an organic acid, or it can be waste acid produced by other industries, so as to achieve simultaneous treatment of acidic and alkaline waste liquid and waste gas.

[0020] Furthermore, the alkaline liquid is an alkaline waste liquid including sodium hydroxide and sodium aluminate generated during the nickel mesh activation process.

[0021] Furthermore, an alkaline desiccant is loaded into the gas drying pipeline.

[0022] Furthermore, the alkaline desiccant is solid soda lime and / or sodium hydroxide.

[0023] Furthermore, the nickel mesh activation reactor uses alkaline solutions including but not limited to sodium hydroxide solution and potassium hydroxide solution as activation solutions. As an example, sodium hydroxide solution is preferred.

[0024] Furthermore, the electrochemical neutralization treatment device: when the electrochemical treatment device is in a high current discharge or short circuit state, after the discharged hydrogen is conducted to the gas diffusion electrode (negative electrode), the hydrogen will undergo an oxidation reaction under alkaline conditions to consume hydroxide ions to generate water; while the counter electrode undergoes a reduction reaction of oxygen from the air on the gas diffusion electrode (positive electrode) to consume hydrogen ions and also generate water; in addition, in addition to electrochemical neutralization, alkaline waste liquid will also undergo chemical neutralization mainly by diffusion between porous membranes, further accelerating the neutralization treatment of the waste liquid, and correspondingly producing high value-added salts. Subsequently, the neutralized waste liquid is evaporated at low temperature to obtain sodium salt, aluminum salt and water.

[0025] The high current discharge or short circuit state refers to: the electronic circuit between the neutralization treatment device and the low resistance load is connected by a metal wire, or the positive and negative electrodes are directly connected by a metal wire, thereby achieving rapid exhaust gas conversion and waste liquid neutralization treatment.

[0026] According to another aspect of the present invention, a method for simultaneously treating waste gas and waste liquid in a nickel mesh activation process using the above-mentioned device is provided. The method includes that the waste gas generated by the nickel mesh activation reactor first passes through a gas drying pipeline to absorb moisture / impurities, and then enters the negative electrode gas chamber of the negative electrode of the gas diffusion electrode to serve as the negative electrode reaction gas; the waste liquid generated by the nickel mesh activation reactor enters the alkaline liquid reaction chamber of the neutralization treatment device, and the neutralized waste liquid after the reaction of the neutralization treatment device enters the evaporation recovery device for evaporation treatment to recover salt and moisture.

[0027] The present invention has the following advantages:

[0028] The present invention aims to simultaneously treat the generated waste gas and waste liquid through a new electrochemical device and method, and ultimately achieve zero waste gas emissions and obtain high-value recovery of waste liquid (including sodium salt, aluminum salt and water).

[0029] The present invention is a neutralization treatment device that utilizes an oxidation reaction that can consume hydrogen and hydroxide ions under alkaline conditions as a negative electrode reaction and an oxygen reduction reaction that consumes hydrogen ions under acidic conditions as a positive electrode reaction, supplemented by a direct mixed chemical neutralization reaction between porous membrane diaphragms, and combined with low-temperature rotation technology to recover salt and water in the neutralized waste liquid. The present invention can simultaneously treat waste gas and waste liquid in the nickel mesh activation process; the product is only water, and no additional waste gas or waste liquid is discharged, which is green and environmentally friendly; it can be used for a variety of waste liquid treatment problems with different alkalinity strengths; through a complete process route, salt and water in the waste liquid are recovered, and the resource utilization rate is improved. BRIEF DESCRIPTION OF THE DRAWINGS

[0030] In order to more clearly illustrate the implementation methods of the present invention or the technical solutions in the prior art, the following briefly introduces the drawings required for the implementation methods or the description of the prior art. Obviously, the drawings in the following description are only exemplary, and for ordinary technicians in this field, other implementation drawings can be derived from the provided drawings without creative work.

[0031] The structures, proportions, sizes, etc. illustrated in this specification are only used to match the contents disclosed in the specification so as to facilitate understanding and reading by persons familiar with the technology. They are not used to limit the conditions under which the present invention can be implemented, and therefore have no substantial technical significance. Any structural modification, change in proportion or adjustment of size shall still fall within the scope of the technical contents disclosed in the present invention without affecting the effects and purposes that can be achieved by the present invention.

[0032] Figure 1 A green synchronous treatment device for waste gas and waste liquid in a nickel mesh activation process provided in Example 1 of the present invention, wherein 11 is a nickel mesh activation reactor, 22 is a gas drying pipeline, 33 is an electrochemical neutralization treatment device, and 44 is an evaporation recovery device;

[0033] Figure 2 The electrochemical neutralization treatment device provided in Example 1 of the present invention;

[0034] Among them, 1-gas diffusion electrode positive electrode, 101-first gas diffusion layer, 102-first catalyst layer, 2-porous membrane, 3-gas diffusion electrode negative electrode, 301-second gas diffusion layer, 302-second catalyst layer, 4-exhaust gas into the chamber, 5-external circuit connected to the load;

[0035] Figure 3 A hydrogen gas chromatogram provided for Example 4 of the present invention;

[0036] Figure 4 A comparison diagram of hydrogen concentration before and after electrochemical treatment provided in Example 4 of the present invention; wherein a-hydrogen concentration before electrochemical treatment; b-hydrogen concentration after electrochemical treatment;

[0037] Figure 5 Comparison diagrams before and after low-temperature rotary evaporation provided in Example 4 of the present invention; wherein a-liquid diagram before low-temperature rotary evaporation after neutralization reaction; b-solid salt and liquid distilled water diagrams obtained after low-temperature rotary evaporation;

[0038] Figure 6 A comparison chart of hydrogen concentrations at different times of electrochemical treatment provided in Example 5 of the present invention; wherein, a-hydrogen concentration before electrochemical treatment; b-hydrogen concentration after 90s of electrochemical treatment; c-hydrogen concentration after 130s of electrochemical treatment. DETAILED DESCRIPTION

[0039] The following is a description of the implementation of the present invention by specific embodiments. People familiar with the art can easily understand other advantages and effects of the present invention from the contents disclosed in this specification. Obviously, the described embodiments are part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0040] The reaction mechanism of the electrochemical treatment device of the present invention is:

[0041] Positive electrode: O 2 +4H + +4e - →2H 2 0(E 0 =1.23V);

[0042] Negative electrode: H 2 +2OH - →2H 2 0+2e - (E 0 =-0.83V);

[0043] Overall discharge reaction:

[0044] O 2 +4H + +2H 2 +4OH - →6H 2 0.

[0045] Principle of the present invention: The present invention first directly converts the waste gas mainly composed of hydrogen into water by reacting with hydroxide ions by using a rapid electrochemical neutralization treatment device, and simultaneously neutralizes and treats the alkaline waste liquid mainly composed of sodium hydroxide and sodium aluminate. The specific reactions involved in the neutralization treatment device are: when the electrochemical treatment device is in a high current discharge or short circuit state, after the discharged hydrogen is conducted to the gas diffusion electrode (negative electrode), the hydrogen will undergo an oxidation reaction under alkaline conditions to consume hydroxide ions and generate water; while the counter electrode undergoes a reduction reaction of oxygen from the air on the gas diffusion electrode (positive electrode) to consume hydrogen ions and generate water; in addition, in addition to electrochemical neutralization, the alkaline waste liquid will also undergo chemical neutralization mainly by diffusion between the porous membranes, further accelerating the neutralization treatment of the waste liquid, and correspondingly producing high value-added salt.

[0046] The high current discharge or short circuit state refers to: the electronic circuit between the neutralization treatment device and the low resistance load is connected by a metal wire, or the positive and negative electrodes are directly connected by a metal wire, thereby realizing rapid exhaust gas conversion and waste liquid neutralization treatment.

[0047] Example 1

[0048] This embodiment provides a green synchronous treatment device for waste gas and waste liquid in a nickel mesh activation process:

[0049] The device is as Figure 1 As shown, it includes a nickel mesh activation reactor 11, a gas drying pipeline 22, an electrochemical neutralization treatment device 33 and an evaporation recovery device 44;

[0050] The nickel mesh activation reactor 11 is used to activate the nickel mesh;

[0051] The gas drying pipeline 22 is provided with an alkaline desiccant for removing water and acidic gas; the alkaline desiccant is solid soda lime and / or sodium hydroxide.

[0052] Electrochemical neutralization treatment device 33 such as Figure 2 As shown; the electrochemical neutralization treatment device comprises a gas diffusion electrode positive electrode 1, an acidic liquid reaction chamber 6, a porous membrane 2, an alkaline liquid reaction chamber 7, a gas diffusion electrode negative electrode 3, an exhaust gas inlet chamber 4 and an external circuit 5 connected to a load; the oxygen of the gas diffusion electrode positive electrode 1 comes from the air, and the gas of the gas diffusion electrode negative electrode 3 comes from the exhaust gas in the nickel mesh activation process; the external circuit 5 connected to the load is connected to the gas diffusion electrode positive electrode 1 and the gas diffusion electrode negative electrode 3;

[0053] A first gas diffusion layer 101 and a first catalyst layer 102 are sequentially arranged between the gas diffusion electrode positive electrode 1 and the acidic liquid reaction chamber 6; a second gas diffusion layer 301 and a second catalyst layer 302 are arranged between the gas diffusion electrode negative electrode 3 and the alkaline liquid reaction chamber 7;

[0054] The gas diffusion electrode positive electrode 1 and the gas diffusion electrode negative electrode 3 are both obtained by mixing and grinding a catalyst, conductive carbon black and a binder solution, and then applying the mixture on the surface of a hydrophobic carbon cloth and drying the mixture; the catalyst is a platinum-based catalyst, a low-platinum catalyst or a non-platinum catalyst.

[0055] The porous membrane 2 is made of one or a mixture of fibers, polytetrafluoroethylene, polyvinylidene fluoride, woven fabrics and plastics.

[0056] The acidic liquid is an inorganic acid and / or an organic acid.

[0057] The alkaline liquid is an alkaline waste liquid including sodium hydroxide and sodium aluminate generated during the nickel mesh activation process.

[0058] The evaporation recovery device 44 is used to evaporate the neutralized waste liquid to obtain sodium salt, aluminum salt and water.

[0059] Example 2

[0060] This embodiment provides a green synchronous treatment device for waste gas and waste liquid in a nickel mesh activation process:

[0061] In this embodiment, which is a laboratory experiment, the nickel mesh activation reactor 11 and the gas drying pipeline 22 are directly connected to the electrochemical neutralization treatment device 33 through a conduit;

[0062] The nickel mesh activation reactor 11 is used to activate the nickel mesh. The nickel mesh activation reactor 11 is a sealable glass or organic glass reactor. The sodium hydroxide activation solution can be added in advance or subsequently. The size of the container can be flexibly designed according to the processing scale.

[0063] The gas drying pipeline 22 is composed of a general U-shaped glass pipeline, and a proper amount of alkaline desiccant is added to the pipeline. In this embodiment, soda lime and / or sodium hydroxide solid is added. The gas drying pipeline 22 can further reduce the moisture content of the exhaust gas, which is beneficial to maintaining the stability of the subsequent treatment device.

[0064] The evaporation recovery device 44 is a rotary evaporator.

[0065] The rest is completely consistent with Example 1.

[0066] Example 3

[0067] This embodiment provides a process for green synchronous treatment of waste gas and waste liquid in a nickel mesh activation process using the device of embodiment 1 or embodiment 2:

[0068] Step 1: Preparation of electrodes

[0069] The catalyst, conductive carbon black and binder solution are mixed and ground, and then applied to the surface of the hydrophobic carbon cloth and dried; the catalyst is a platinum-based catalyst, a low-platinum catalyst or a non-platinum catalyst;

[0070] Step 2: Processing

[0071] The nickel mesh activated alkaline waste liquid is placed in the alkaline liquid reaction chamber 7, the acid is placed in the acidic liquid reaction chamber 6, the nickel mesh activation reactor 11 is added with sodium hydroxide solution for activation reaction, and the liquid of the activation reaction is continuously pumped into the alkaline liquid reaction chamber 7; the gas of the activation reaction enters the gas drying pipeline 22, and the waste gas (mainly containing hydrogen) obtained after the reaction is completed enters the waste gas passage chamber 4, and the waste gas passes through the gas diffusion electrode cathode 3, the second gas diffusion layer 301, and the second catalyst layer 302 in turn into the alkaline liquid reaction chamber 7. After power is turned on, the cathode undergoes the reaction: H 2 +2OH - →2H 20+2e - ; Lose electrons to generate water; The electrons enter the acidic liquid reaction chamber 6 through the porous membrane 2, and the positive electrode passes through O 2 +4H + +4e - →2H 2 0, obtains electrons to generate water, the oxygen obtained at the positive electrode comes from the air, and the oxygen obtained in the air passes through the gas diffusion electrode positive electrode 1, the first gas diffusion layer 101 and the first catalyst layer 102 in sequence, and reacts in the acidic liquid reaction chamber 6; the neutralized waste liquid is transferred to the evaporation recovery device 44 to recover water and salt.

[0072] Example 4

[0073] This embodiment provides a process for green simultaneous treatment of waste gas and waste liquid in a nickel mesh activation process using the device of embodiment 2:

[0074] (1) Preparation of gas diffusion electrode positive electrode 1 and gas diffusion electrode negative electrode 3, the preparation process is as follows: ① 20 mg of platinum carbon catalyst, 100 mg of conductive carbon black and 1 mL of binder solution (50 wt% PTFE solution) were mixed and ground and then applied to the carbon-coated side of the hydrophobic carbon cloth (the active area of ​​the electrode is 16 cm 2 ② Place the prepared electrode in a 60℃ oven for 2h to remove the solvent in the coating. ③ After the electrode is dried, place it in aluminum foil and press it with a pressure of 15MPa for 10 seconds to further prevent the catalyst from peeling off.

[0075] (2) 150 mL of nickel mesh activated alkaline waste liquid (i.e., waste liquid generated by preparing Raney nickel) is prepared. Specifically, 5 g of aluminum-nickel alloy material (Raney nickel precursor) is reacted with 500 mL of 5.0 M sodium hydroxide aqueous solution. After the reaction is completed, residual solids mainly composed of nickel are removed by filtration. The filtrate obtained is the waste liquid. 150 mL of the waste liquid is taken as the nickel mesh activated alkaline waste liquid, and then introduced into the alkaline liquid reaction chamber 7 through a peristaltic pump.

[0076] (3) Prepare 30 mL of 5.0 M sodium hydroxide aqueous solution as the reaction solution for nickel mesh activation, and pour it into the separatory funnel of the nickel mesh activation reactor 11 for later use; 0.5 g of aluminum-nickel alloy material (Raney nickel precursor, Adamas brand, 48-50% Nibasis, 150 μm, powder with higher activity) is placed in the nickel mesh activation reactor 11, and when the experiment starts, it is directly contacted with the sodium hydroxide aqueous solution to trigger the activation reaction, and the resulting waste gas enters the drying pipe 22 for treatment and then enters the waste gas inlet chamber 4.

[0077] (4) Prepare 375 mL of 1.0 M sulfuric acid aqueous solution as the neutralizing solution for the counter electrode, and then introduce it into the acidic liquid reaction chamber 6 through a peristaltic pump.

[0078] (5) The porous membrane 2 used in this example is a porous hydrophilic polytetrafluoroethylene membrane with an average pore size of 0.45 μm and a membrane thickness of 0.15 mm.

[0079] (6) The nickel mesh activation reactor 11 is equipped with an exhaust gas pipeline. After being treated by the gas drying pipeline 22, the exhaust gas is directly conducted to the electrochemical neutralization treatment device 33 and then enters the chamber 4 for subsequent reactions. Finally, the exhaust port is directly connected to the Baoshian hydrogen detector through a conduit to monitor the exhaust gas (hydrogen) concentration in real time; and the gas chamber of the gas diffusion electrode positive electrode 1 is directly in contact with the air, and the oxygen in the air can react with the hydrogen ions in the acidic liquid reaction chamber 6 to generate a reduction reaction. The composition of the exhaust gas was also verified to be hydrogen by gas chromatography analysis before the experiment. Figure 3 shown.

[0080] (7) Before the activation reaction begins, the hydrogen-specific detector shows that the exhaust gas (hydrogen) concentration is 0.0-0.1 vol%.

[0081] (8) Before starting the experiment, the peristaltic pump was started. After the liquid completely circulated through the two chambers and the liquid circulation in the system was normal, the separatory funnel in the nickel mesh activation reactor 11 was opened and the sodium hydroxide solution was poured into the reactor. The activation reaction immediately occurred and the generation of bubbles could be clearly observed. The exhaust gas (hydrogen) was also quickly detected by the detector. The concentration value rose to 14.8% within 10 seconds (see Figure 4 a).

[0082] (9) At this time, the positive and negative electrodes of the electrochemical neutralization treatment device 33 are directly connected through wires to form a short circuit, and the neutralization reaction treatment is carried out at the maximum current or the fastest speed. The concentration value stops rising and quickly drops to 2.7% within 48 seconds (see Figure 4 b). Further optimization of the effect can be achieved simply by increasing the number of single cells and the design of the battery stack.

[0083] (10) During the test, flocculent precipitation of the neutralization product was also clearly observed in the liquid circulation pipe chamber, which means that the device is able to neutralize the alkaline waste liquid while treating the waste gas (hydrogen), which directly proves the feasibility and practicality of the device and process.

[0084] (11) A large amount of white precipitate will be generated in the liquid after being treated by the electrochemical neutralization treatment device 33 of the present invention, such as Figure 5 a. After low-temperature rotary evaporation, salt and pure distilled water can be recovered ( Figure 5 b).

[0085] For 150mL of waste liquid (waste alkali liquid only), when the waste liquid flow rate is 4mL / min, after all the neutralization treatment is completed, the treatment process takes a total of about 39 minutes.

[0086] Example 5

[0087] This embodiment provides a green synchronous treatment process for waste gas and waste liquid in a nickel mesh activation process:

[0088] This embodiment will use a commercially available nickel mesh that has been sprayed with a Raney nickel precursor but has not been activated by alkaline solution (referred to as unactivated nickel mesh) to demonstrate a green synchronous treatment device and method for waste gas and waste liquid in a nickel mesh activation process.

[0089] (1) Preparation of gas diffusion electrode positive electrode 1 and gas diffusion electrode negative electrode 3, the preparation process is as follows: ① 20 mg of platinum carbon catalyst, 100 mg of conductive carbon black and 1 mL of binder solution (50 wt% PTFE solution) were mixed and ground and then applied to the carbon-coated side of the hydrophobic carbon cloth. ② The prepared electrode was placed in a 60°C oven for 2 hours to remove the solvent in the coating. ③ After the electrode was dried, it was placed in aluminum foil and pressed at a pressure of 15 MPa for 10 seconds to further prevent the catalyst from peeling off.

[0090] (2) 150 mL of nickel mesh activated alkaline waste liquid (i.e., waste liquid generated by preparing Raney nickel) was prepared. Specifically, 15.3 g of unactivated nickel mesh (purchased from Pfizer Wire Mesh Manufacturing Plant, with an aluminum content of about 23%) was reacted with 500 mL of 5.0 M sodium hydroxide aqueous solution. After the reaction was completed (at room temperature and for more than two hours), the nickel mesh that had been completely reacted was filtered out. The obtained filtrate was the waste liquid. 150 mL of the waste liquid was taken as the nickel mesh activated alkaline waste liquid, and subsequently introduced into the alkaline liquid reaction chamber 7 through a peristaltic pump. In addition, the exhaust gas during the reaction was also collected. After characterization by gas chromatography, it can be confirmed that the gas component is hydrogen ( Figure 3 ).

[0091] (3) Prepare 100 mL of 5.0 M sodium hydroxide aqueous solution as the reaction solution for nickel mesh activation, and pour it into the separatory funnel of the nickel mesh activation reactor 11 for standby use; 5.6 g of unactivated nickel mesh is placed in the activation reactor, and when the experiment starts, it is directly contacted with the sodium hydroxide aqueous solution to trigger the activation reaction, and the resulting waste gas enters the drying pipe 22 for treatment and then enters the waste gas inlet chamber 4.

[0092] (4) Prepare 300 mL of 1.0 M sulfuric acid aqueous solution as a neutralizing solution for the counter electrode, and then introduce it into the acidic liquid chamber through a peristaltic pump.

[0093] (5) The porous membrane 2 used in this example is a porous hydrophilic polytetrafluoroethylene membrane with a pore size range of 0.3-0.6 μm, an average pore size of 0.45 μm, and a membrane thickness of 0.15 mm.

[0094] (6) The nickel mesh activation reactor 11 is equipped with a waste gas pipeline. After being treated by the gas drying pipeline 22, the waste gas is directly conducted to the electrochemical neutralization treatment device 33 and then enters the chamber 4 for subsequent reaction. Finally, the exhaust port is directly connected to the Baoshian hydrogen dedicated detector through a conduit to monitor the waste gas (hydrogen) concentration in real time. The gas chamber of the counter electrode is directly in contact with the air, and the oxygen in the air can react with the hydrogen ions in the acidic chamber of the counter electrode to undergo a reduction reaction.

[0095] (7) Before the activation reaction begins, the hydrogen-only detector shows that the exhaust gas (hydrogen) concentration is 0.0 vol%.

[0096] (8) Before starting the experiment, the peristaltic pump was started. After the liquid completely circulated through the two chambers and the liquid circulation in the system was normal, the separatory funnel in the nickel mesh activation reactor 11 was opened and the sodium hydroxide solution was poured into the reactor. The activation reaction immediately occurred. It was clearly observed that many bubbles were generated around the nickel mesh. The exhaust gas (hydrogen) was also quickly detected by the detector. The concentration value rose to 2.0% within 33 seconds (see Figure 6 a).

[0097] (9) At this time, the positive and negative electrodes of the neutralization reaction device are immediately connected directly through wires to form a short circuit, and the neutralization reaction is carried out at the maximum current or at the fastest speed. The concentration value stops rising and quickly drops to 0.9% within 90 seconds (see Figure 6 b), continue to process and after about 40 seconds it drops to 0.1% (see Figure 6 c). Further optimization of the effect can be achieved simply by increasing the number of single cells and the design of the battery stack.

[0098] For 150mL of waste liquid (waste alkali liquid only), when the waste liquid flow rate is 4mL / min, after all the neutralization treatment is completed, the treatment process takes about 40 minutes in total.

[0099] Comparative Example 1

[0100] In this comparative example, the porous membrane is replaced by an ion exchange membrane, and the electrode of the prior patent CN114122569A is used. The results show that when the waste liquid flow rate is 40 mL / min, after all the neutralization treatment is completed, the total treatment time is about 2880 minutes or 2 days.

[0101] Comparative Example 2

[0102] In this comparative example, the negative electrode is replaced with a hydride electrode (the electrode preparation method is the same as the method of Example 1 of Chinese Patent CN114122569A), and the rest is completely consistent with Example 4. Results show that hydrogen cannot be processed after the replacement.

[0103] Comparative Example 3

[0104] This comparative example uses ordinary direct current, the current is 20 mA, and the electrochemical neutralization device of the prior patent CN114122569A is used. The results show that when the waste liquid flow rate of 34 mL (only waste alkali) is 40 mL / min, after all the neutralization treatment is completed, the total time required for the treatment process is about 2880 minutes or 2 days.

[0105] The present invention utilizes an oxidation reaction that consumes hydrogen and hydroxide ions under alkaline conditions as a negative electrode reaction and an oxygen reduction reaction that consumes hydrogen ions under acidic conditions as a positive electrode reaction, supplemented by a direct mixed chemical neutralization reaction between porous membrane diaphragms, and combined with low-temperature rotation technology to recover salt and water in the neutralized waste liquid. It can simultaneously treat waste gas and waste liquid in the nickel mesh activation process; the product is only water, and no additional waste gas or waste liquid is discharged, which is green and environmentally friendly; it can treat waste liquids of various alkaline strengths; and through a complete process route, it can recover salt and water in the waste liquid, thereby improving resource utilization.

[0106] Although the present invention has been described in detail above by general description and specific embodiments, it is obvious to those skilled in the art that some modifications or improvements can be made to the present invention. Therefore, these modifications or improvements made without departing from the spirit of the present invention all belong to the scope of protection claimed by the present invention.

Claims

1. A device for synchronously treating waste gas and waste liquid in a nickel mesh activation process, characterized in that: The device comprises a nickel mesh activation reactor, a gas drying pipeline, an electrochemical neutralization treatment device and an evaporation recovery device; wherein the electrochemical neutralization treatment device comprises a gas diffusion electrode positive electrode, an acidic liquid reaction chamber, a porous membrane, an alkaline liquid reaction chamber and a gas diffusion electrode negative electrode; the oxygen of the gas diffusion electrode positive electrode comes from the air, and the gas of the gas diffusion electrode negative electrode comes from the waste gas in the nickel mesh activation process.

2. The device for synchronously treating waste gas and waste liquid in a nickel mesh activation process according to claim 1, characterized in that: The gas diffusion electrode positive electrode and the gas diffusion electrode negative electrode are both obtained by mixing and grinding a catalyst, conductive carbon black and a binder solution, and then applying the mixture on the surface of a hydrophobic carbon cloth and drying the mixture.

3. The device for synchronously treating waste gas and waste liquid in a nickel mesh activation process according to claim 2, characterized in that: The catalyst is a platinum-based catalyst, a low-platinum catalyst or a non-platinum catalyst.

4. The device for synchronously treating waste gas and waste liquid in a nickel mesh activation process according to claim 2, characterized in that: The mixing ratio of the catalyst, the conductive carbon black and the binder solution is 0.1-40%: 30-85%: 5%-30%.

5. The device for synchronously treating waste gas and waste liquid in a nickel mesh activation process according to claim 2, characterized in that: The binder is PTFE (polytetrafluoroethylene) or PVDF (polyvinylidene fluoride).

6. The device for synchronously treating waste gas and waste liquid in a nickel mesh activation process according to claim 1, characterized in that: The thickness of the gas diffusion electrode is 10-100 microns.

7. The device for synchronously treating waste gas and waste liquid in a nickel mesh activation process according to claim 1, characterized in that: The pore size of the porous membrane is 0.05-20 micrometers; the membrane thickness is 0.02-1 millimeter.

8. The device for synchronously treating waste gas and waste liquid in a nickel mesh activation process according to claim 1, characterized in that: The porous membrane is prepared from one or more of fiber, polytetrafluoroethylene, polyvinylidene fluoride, woven fabric and plastic.

9. The device for synchronously treating waste gas and waste liquid in a nickel mesh activation process according to claim 1, characterized in that: The electrochemical neutralization treatment device adopts a large current discharge or short circuit state.

10. A method for synchronously treating waste gas and waste liquid in a nickel mesh activation process using any device of claims 1-9, characterized in that: The method comprises the following steps: the waste gas generated by the nickel mesh activation reactor is first directed to a gas drying pipeline to absorb moisture / impurities, and then enters a negative electrode gas chamber of a negative electrode of a gas diffusion electrode to serve as a negative electrode reaction gas; the waste liquid generated by the nickel mesh activation reactor enters an alkaline liquid reaction chamber of a neutralization treatment device, and the neutralized waste liquid after the reaction of the neutralization treatment device is completed enters an evaporation recovery device for evaporation treatment to recover salt and moisture.

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