An integrated device and process for simultaneously treating sulfur-containing wastewater and formaldehyde using an electrochemical method

Abstract

The present invention discloses an integrated device and process for the simultaneous treatment of sulfur-containing wastewater and formaldehyde by electrochemical method. The electrolytic cell comprises an absorption zone, an anode zone and a cathode zone, wherein the absorption zone is arranged above the anode zone, and the anode zone is connected to one end of the cathode zone; there is no partition between the absorption zone and the anode zone, and the anode zone is connected to the cathode zone by OH. ‑ The selective permeable membrane is separated from the cathode area. The electrochemical method is used to simultaneously treat sulfur-containing wastewater and formaldehyde integrated device and process. The sulfur-containing wastewater enters the electrolytic cell, and the OH generated at the cathode ‑ The sulfur and S that migrate to the anode area and precipitate on the anode surface 2‑ Soluble polysulfides are generated by coupling, and the polysulfides are sprayed through the water distribution device. Low-concentration formaldehyde waste gas is released through the gas distribution device and oxidized in the filler area to generate sodium formate, while the polysulfides are reduced to sulfides. The sulfides continue to be oxidized to polysulfides at the anode. The waste liquid containing polysulfides and sodium formate is acidified to obtain sulfur and formic acid.

Description

Technical Field

[0001] The present invention relates to the technical field of combined treatment of wastewater and waste gas, and in particular to an integrated device and process for synchronously treating sulfur-containing wastewater and formaldehyde using an electrochemical method. Background Art

[0002] The petrochemical, printing, pharmaceutical, and fuel industries generate large amounts of wastewater and exhaust gas. Sulfide in the wastewater and formaldehyde in the exhaust gas are both toxic and harmful, causing significant harm to both humans and the environment. Therefore, seeking a simple, gentle, efficient, and secondary pollution-free treatment method is crucial for both human health and environmental development.

[0003] Traditional methods for treating sulfur-containing wastewater include acidification absorption, steam stripping, chemical flocculation, air oxidation, etc. The acidification method is to remove sulfur under acidic conditions. 2- It is converted into H2S gas. Since hydrogen sulfide is toxic and corrosive, it places high demands on the corrosion resistance and leakage prevention of the equipment. The stripping method uses air to blow out the sulfide in the wastewater. Due to its high energy consumption and complex process, it is not suitable for wastewater with low sulfur content. The chemical flocculation method adds ferrous salt or ferric salt to the wastewater to generate insoluble salts and then separates and removes them. For high-concentration sulfur-containing wastewater, the drug consumption also increases sharply. The air oxidation method uses air to remove S 2- Oxidation produces non-toxic thiosulfate and sulfate, but the solubility of oxygen in water is low, and the efficiency of pure gas-liquid mass transfer is very low. Currently, electrochemical methods are gaining increasing attention in the desulfurization field due to their ease of operation, low energy consumption, no secondary pollution, and high value-added by-products.

[0004] Formaldehyde waste gas from industrial production generally has low concentrations and is difficult to purify. Common treatment methods include molecular sieve adsorption, catalytic oxidation, and catalytic combustion. Molecular sieve adsorption primarily uses solid molecular sieves (activated carbon molecular sieves and zeolite molecular sieves) to adsorb toxic and harmful substances in the waste gas. Desorption occurs when the molecular sieve reaches saturation, and the adsorbent requires regular replacement and regeneration, which greatly limits the application of adsorption. Catalytic oxidation uses an oxidant in the presence of a catalyst to oxidize formaldehyde into carbon dioxide and water. However, the catalyst is often a precious metal catalyst and is susceptible to poisoning and deactivation, increasing the cost of the treatment process. Combustion uses catalytic combustion technology to deeply oxidize formaldehyde into carbon dioxide and water, which requires additional heating equipment and wastes energy. Because formaldehyde exhibits strong oxidizing properties under alkaline conditions, it has attracted attention for its ability to be oxidized into products such as sodium formate under the action of weak oxidants.

[0005] In industrial production, the generation of sulfur-containing wastewater is often accompanied by the generation of formaldehyde waste gas. The use of electrolysis to treat sulfur-containing wastewater and the use of formaldehyde in alkaline solution to degrade formaldehyde have attracted widespread attention due to their simple operation, low energy consumption, no secondary pollution, and high value-added by-products. However, existing devices have the following problems: First, the current sulfur-containing wastewater treatment device and formaldehyde purification device are often two independent sets of devices, which not only wastes the limited production area, but also the independent operation of the two sets of devices will undoubtedly increase the treatment cost; second, the existing process often over-oxidizes formaldehyde into water and carbon dioxide, products of no economic value; third, the removal of formaldehyde often involves the consumption of large amounts of oxidants and adsorbents, which undoubtedly further increases the treatment cost. Summary of the Invention

[0006] The purpose of this section is to summarize some aspects of the embodiments of the present invention and briefly introduce some preferred embodiments. Some simplifications or omissions may be made in this section and the abstract and title of this application to avoid obscuring the purpose of this section, the abstract and the title of the invention, and such simplifications or omissions should not be used to limit the scope of the present invention.

[0007] In view of the problems existing in the existing integrated device for simultaneously treating sulfur-containing wastewater and formaldehyde using the electrochemical method, the present invention is proposed.

[0008] Therefore, the purpose of the present invention is to provide an integrated device for the simultaneous electrochemical treatment of sulfur-containing wastewater and formaldehyde, the purpose of which is to be able to use the device to carry out simultaneous treatment of sulfur-containing wastewater and formaldehyde processes.

[0009] In order to solve the above technical problems, the present invention provides the following technical solutions: the electrolytic cell comprises an absorption zone, an anode zone and a cathode zone, wherein the absorption zone is arranged above the anode zone, and the anode zone is connected to one end of the cathode zone; there is no partition between the absorption zone and the anode zone, and the anode zone is connected to the cathode zone through OH - The cathode region is separated by a selective permeable membrane; and the anode region is connected to the cathode region via a constant voltage DC power supply, and the constant voltage DC power supply is connected to the anode region via a sliding switch mechanism.

[0010] As a preferred solution of the integrated device for simultaneous electrochemical treatment of sulfur-containing wastewater and formaldehyde according to the present invention, the absorption zone includes a tail gas outlet arranged on its outer surface, a tail gas detector arranged on the tail gas outlet, a water distribution mechanism arranged in the absorption zone, a filler mechanism provided with a stainless steel filler support mesh plate in the absorption zone and located below the water distribution mechanism, and a gas distribution mechanism that releases exhaust gas to the filler mechanism and is arranged in the anode zone, and the gas distribution mechanism is connected to the tail gas monitor.

[0011] As a preferred solution of the integrated device for simultaneous electrochemical treatment of sulfur-containing wastewater and formaldehyde according to the present invention, the anode area includes a plurality of anode rods arranged in sequence therein, a first conductive metal rod arranged at one end of the anode rod and connected to the positive pole of the constant-voltage DC power supply, an anode liquid inlet and outlet arranged at one end of the anode area and located below the anode rod, and a plane arranged on the inner surface of the anode area.

[0012] As a preferred solution of the integrated device for simultaneous electrochemical treatment of sulfur-containing wastewater and formaldehyde according to the present invention, the cathode area includes a cathode plate arranged inside the cathode area, a second conductive metal rod arranged at one end of the cathode plate and connected to the negative pole of the constant-voltage DC power supply, a hydrogen storage tank arranged on the outer surface of the cathode area and connected to its hydrogen outlet, a pressure gauge arranged on the outer surface of the hydrogen storage tank, and a cathode liquid inlet arranged at one end of the cathode area and located below the cathode plate.

[0013] As a preferred solution of the integrated device for simultaneous electrochemical treatment of sulfur-containing wastewater and formaldehyde according to the present invention, the water distribution mechanism includes a water pipe fixed horizontally in the absorption area, a plurality of nozzles arranged on the outer surface of the water pipe, and nozzles arranged on the nozzles, and the nozzles are connected to the water pipe by threads.

[0014] As a preferred solution of the integrated device for the simultaneous electrochemical treatment of sulfur-containing wastewater and formaldehyde according to the present invention, the gas distribution mechanism adopts a stainless steel hollow rectangular parallelepiped structure, and a plurality of small holes are opened on the top thereof to facilitate gas release;

[0015] The outer surfaces of the anode rod and cathode plate are coated with a bifunctional catalyst.

[0016] As a preferred solution of the integrated device for simultaneous electrochemical treatment of sulfur-containing wastewater and formaldehyde described in the present invention, the sliding switch mechanism is a paddle, comprising a first copper plate arranged on its outer surface, and a second copper plate fixed to different anode ends of the sliding switch mechanism and a third copper plate at the power supply end, the first copper plate is respectively in contact with the second copper plate connected to different anode electrodes and the third copper plate at the power supply end, and the operation and stop of different anode rods are controlled by toggling the paddle of the sliding switch mechanism; the cathode area also includes a dryer arranged on the outer surface of the hydrogen storage tank and connected to the hydrogen outlet.

[0017] In view of the problems existing in the above-mentioned existing integrated process for the simultaneous treatment of sulfur-containing wastewater and formaldehyde by electrochemical methods, the present invention is proposed.

[0018] Therefore, another object of the present invention is to provide an integrated process for the simultaneous treatment of sulfur-containing wastewater and formaldehyde by electrochemical methods, the purpose of which is to be able to use this method to simultaneously treat sulfur-containing wastewater and formaldehyde processes.

[0019] To solve the above technical problems, the present invention provides the following technical solutions: a catalyst preparation method and a method for obtaining sulfur and formic acid; wherein the catalyst preparation method is as follows: a mixed base material is dissolved in deionized water and introduced into a reactor for reaction to obtain a catalyst precursor powder; the precursor powder is calcined; the calcined powder is mixed with water, ethanol, and Nafion solution to obtain a suspension; the suspension is coated on the outer surfaces of the anode rod and cathode plate and air-dried;

[0020] Among them, the method for simultaneously treating sulfur-containing wastewater and formaldehyde is as follows: transport the wastewater to the anode area and the cathode area; operate the electrolysis equipment and perform oxidation and reduction reactions, and at the same time detect whether the exhaust gas meets the standards; if it meets the standards, it is discharged; if it does not meet the standards, it is treated together with formaldehyde and exhaust gas; then switch the anode rod and repeat the reaction, and cycle back to detect whether the exhaust gas meets the standards until the treated liquid is treated and the process is completed.

[0021] As a preferred embodiment of the integrated process for the simultaneous electrochemical treatment of sulfur-containing wastewater and formaldehyde described in the present invention, the catalyst preparation method specifically comprises: dissolving ammonium fluoride, urea, and one or more of ferric nitrate, nickel nitrate, and cobalt nitrate in deionized water to prepare a mixed solution; adding the mixed solution to a stainless steel autoclave, reacting at 140°C for 8 hours, and then centrifuging, washing, and drying to obtain a catalyst precursor powder; placing the catalyst precursor powder in a tubular calcining furnace with sodium hypophosphite as a phosphorus source placed upstream, and annealing and calcining at 350°C for 2 hours to obtain a transition metal phosphide powder; mixing the prepared transition metal phosphide powder with water, ethanol, and Nafion solution, ultrasonically obtaining a uniformly dispersed suspension, and coating the suspension on the surfaces of the cathode plate and anode rod, and air-drying for later use.

[0022] As a preferred solution of the integrated process for the simultaneous treatment of sulfur-containing wastewater and formaldehyde by electrochemical method according to the present invention, the following steps are specifically adopted: opening the first valve and the fourth valve, respectively transporting the sulfur-containing wastewater to the anode area and the cathode area until all the anode rods and cathode plates are submerged; connecting a constant voltage DC power supply, controlling the electrolysis voltage at 0.5-10V, and continuously generating S in the anode area; 2- Oxidation reaction, the generated sulfur adheres to the surface of the anode rod; the cathode area continues to generate H + The H2 produced by the reduction reaction is collected by the hydrogen recovery tank, and the by-product OH- migrates to the anode area through the OH-selective permeable membrane; after a period of electrolysis, the surface of the anode rod is completely covered with sulfur. At this time, the paddle of the sliding switch is toggled to switch to a different anode rod, and the reaction is repeated to continue to remove sulfur from the wastewater. 2- , and the sulfur covered in the working electrode before switching generates polysulfide under the action of OH- until it is completely dissolved and then used in the next electrolysis process; n 2-When the concentration is large enough, open the second valve and start the water pump to transport the anode liquid to the water distribution mechanism. At the same time, the exhaust gas containing formaldehyde is released through the gas distribution mechanism. The formaldehyde is oxidized into sodium formate, and S n 2- Restored to S 2- The tail gas continues to be oxidized at the anode, and passes through the tail gas detector. The tail gas that meets the standards is directly discharged into the atmosphere, and the tail gas that does not meet the standards is transported to the gas distribution mechanism together with the formaldehyde waste gas. 2- After the standards are met, the third valve is opened to transport the anolyte to be treated out of the anode area, and waste acid is added to the anolyte to obtain sulfur and formic acid.

[0023] Beneficial effects of the present invention:

[0024] (1) The present invention utilizes the weak reducing property of polysulfides and the oxidizing property of formaldehyde under alkaline conditions to integrate a sulfur-containing wastewater electrolysis device and a formaldehyde oxidation absorption device. This can not only achieve efficient removal of sulfides in sulfur-containing wastewater, but also simultaneously remove formaldehyde in formaldehyde waste gas. Moreover, the by-products have a high added value, solving the industry problems of large device footprint and high treatment cost, and has good application prospects.

[0025] (2) The present invention utilizes polysulfide generated by electrolysis of sulfide to oxidize formaldehyde, which not only avoids the use of other oxidants but also avoids excessive oxidation of formaldehyde, thereby increasing the added value of formaldehyde oxidation products;

[0026] (3) The present invention sets an anion exchange membrane to make the OH generated by the cathode reaction - It is enriched at the anode and the switching between the anode electrodes is controlled by the sliding switch. Without adding additional alkali, the sulfide in the wastewater is efficiently removed, solving the industry problems such as shutdown and electrode regeneration caused by easy passivation of the anode in the electrolytic sulfide wastewater. BRIEF DESCRIPTION OF THE DRAWINGS

[0027] In order to more clearly illustrate the technical solutions of the embodiments of the present invention, the following briefly introduces the drawings required for describing the embodiments. Obviously, the drawings described below are only some embodiments of the present invention. Those skilled in the art can also derive other drawings based on these drawings without inventive effort. Among them:

[0028] Figure 1 This is a schematic diagram of the overall structure of the integrated device for the simultaneous electrochemical treatment of sulfur-containing wastewater and formaldehyde according to the present invention.

[0029] Figure 2 This is an integrated device for the simultaneous electrochemical treatment of sulfur-containing wastewater and formaldehyde. Figure 1 Schematic diagram of the sliding switch mechanism structure.

[0030] Figure 3 The present invention is a schematic flow chart of a catalyst preparation method for an integrated process for the simultaneous electrochemical treatment of sulfur-containing wastewater and formaldehyde.

[0031] Figure 4 The present invention provides a schematic structural diagram of the integrated process for simultaneously treating sulfur-containing wastewater and formaldehyde using an electrochemical method. DETAILED DESCRIPTION

[0032] In order to make the above-mentioned objects, features and advantages of the present invention more obvious and easy to understand, the specific embodiments of the present invention are described in detail below with reference to the accompanying drawings.

[0033] In the following description, many specific details are set forth to facilitate a full understanding of the present invention. However, the present invention may also be implemented in other ways different from those described herein. Those skilled in the art may make similar generalizations without violating the connotation of the present invention. Therefore, the present invention is not limited to the specific embodiments disclosed below.

[0034] Secondly, the term "one embodiment" or "embodiment" herein refers to a specific feature, structure, or characteristic that may be included in at least one implementation of the present invention. The phrase "in one embodiment" appearing in various places throughout this specification does not necessarily refer to the same embodiment, nor does it refer to a separate or selective embodiment that is mutually exclusive of other embodiments.

[0035] Furthermore, the present invention is described in detail with reference to schematic diagrams. For ease of illustration, when describing the embodiments of the present invention, cross-sectional views illustrating device structures may be partially enlarged and not to scale. Furthermore, the schematic diagrams are merely illustrative and should not limit the scope of protection of the present invention. Furthermore, in actual production, the three-dimensional dimensions of length, width, and depth should be included.

[0036] Example 1

[0037] Reference Figures 1-2 , which is the first embodiment of the present invention, provides an integrated device for simultaneously treating sulfur-containing wastewater and formaldehyde by electrochemical method. The electrolytic cell F device includes an absorption area 100, an anode area 200 and a cathode area 300.

[0038] The absorption region 100 is disposed above the anode region 200, and the anode region 200 is connected to one end of the cathode region 300; there is no partition between the absorption region 100 and the anode region 200, and the anode region 200 is connected to the cathode region 300 through OH - The selective permeable membrane 201 is separated from the cathode region 300 ; and the anode region 200 is connected to the cathode region 300 via a constant voltage DC power supply 202 , and the constant voltage DC power supply 202 is connected to the anode region 200 via a sliding switch mechanism 206 .

[0039] The sulfur-containing wastewater is transported to the anode area 200 and the cathode area 300, and electrolysis is performed using a constant voltage DC power supply 202, so that the anode area 200 undergoes an oxidation reaction, while the cathode area 300 undergoes a reduction reaction, which is then collected and the by-product OH is finally generated. - Through OH - The selective permeable membrane 201 migrates to the anode region 200, and after the electrolysis is completed, the sliding switch mechanism 206 is used to switch, and the polysulfide is repeatedly used until it is completely dissolved and then used for the next electrolysis process until the S in the anode region 200 is completely dissolved. n 2- If the concentration is large enough, it can be released and oxidized, and then the tail gas can be discharged or not discharged and treated again. Finally, when the standard is met, the anolyte to be treated is transported out of the anode area 200, and waste acid is added to the anolyte to obtain sulfur and formic acid.

[0040] During use, the absorption area 100 includes an exhaust gas outlet 101 arranged on its outer surface, an exhaust gas detector 102 arranged on the exhaust gas outlet 101, a water distribution mechanism 103 arranged in the absorption area 100, a stainless steel filler support mesh plate 105 arranged in the absorption area 100 and a filler mechanism 104 located below the water distribution mechanism 103, and a gas distribution mechanism 106 that releases exhaust gas to the filler mechanism 104 and is arranged in the anode area 200, and the gas distribution mechanism 106 is connected to the exhaust gas monitor 102.

[0041] The exhaust gas monitor 102 is used to detect the concentration of formaldehyde in the exhaust gas. When the formaldehyde concentration meets the emission standard, it is directly discharged into the atmosphere. When the formaldehyde concentration in the exhaust gas does not meet the emission standard, the formaldehyde exhaust gas will enter the air distribution mechanism 106 again.

[0042] The filler of the filler mechanism 104 is any one of ceramic sheet filler, plastic hollow ball filler or stainless steel ring filler, and a stainless steel filler supporting mesh plate 105 is provided below.

[0043] The water distribution mechanism 103 includes a water pipe 103a fixed horizontally in the absorption area 100, a plurality of nozzles 103b arranged on the outer surface of the water pipe 103a, and a nozzle 103c arranged on the nozzle 103b. The nozzle 103b is connected to the water pipe 103a through a thread. The gas distribution mechanism 106 adopts a stainless steel hollow rectangular structure, and a plurality of small holes are opened on the top to facilitate gas release.

[0044] The nozzle 103c of the nozzle 103b is set to be hemispherical, and a number of small holes are opened on the hemispherical surface. Each nozzle 103b is connected to the water pipe 103a through a thread, which makes it easy to replace any nozzle 103b separately.

[0045] The anode area 200 includes a plurality of anode rods 203 arranged in sequence therein, a first conductive metal rod 204 arranged at one end of the anode rod 203 and connected to the positive pole of the constant voltage DC power supply 202, an anode liquid inlet and outlet 205 arranged at one end of the anode area 200 and located below the anode rod 203, and a plane 207 arranged on the inner surface of the anode area 200.

[0046] The sliding switch mechanism 206 is a paddle, including a first copper sheet 206a arranged on its outer surface, and a second copper sheet 206b fixed to different anode ends of the sliding switch mechanism 206 and a third copper sheet 206c fixed to the power supply end. The first copper sheet 206a is in contact with the second copper sheet 206b connected to different anode electrodes and the third copper sheet 206c connected to the power supply end respectively. By toggling the paddle of the sliding switch mechanism 206, the operation and stop of different anode rods 203 are controlled.

[0047] The cathode area 300 includes a cathode plate 301 arranged inside it, a second conductive metal rod 302 arranged at one end of the cathode plate 301 and connected to the negative pole of the constant voltage DC power supply 202, a hydrogen storage tank 303 arranged on the outer surface of the cathode area 300 and connected to its hydrogen outlet, a pressure gauge 304 arranged on the outer surface of the hydrogen storage tank 303, and a cathode liquid inlet 305 arranged at one end of the cathode area 300 and located below the cathode plate 301.

[0048] The outer surfaces of the anode rod 203 and the cathode plate 301 are coated with a bifunctional catalyst. The cathode area 300 also includes a dryer 306 arranged on the outer surface of the hydrogen storage tank 303 and connected to the hydrogen outlet. The dryer 306 is filled with a desiccant, which can be but is not limited to one of silica gel particles, calcium chloride or calcium oxide.

[0049] Example 2

[0050] Reference Figure 3 , which is the second embodiment of the present invention, differs from the first embodiment in that: the synthesis method of the bifunctional catalyst.

[0051] The catalyst preparation method is as follows:

[0052] The mixed base materials are dissolved in deionized water and placed in a reactor for reaction to obtain catalyst precursor powder;

[0053] calcining the precursor powder;

[0054] The calcined powder is mixed with water, ethanol and Nafion solution to obtain a suspension;

[0055] The suspension is applied to the outer surfaces of the anode rod 203 and the cathode plate 301 and air-dried.

[0056] Compared with the above content, further, there are concrete solutions as follows:

[0057] dissolving ammonium fluoride, urea and one or more of ferric nitrate, nickel nitrate and cobalt nitrate in deionized water to prepare a mixed solution;

[0058] The mixed solution was added to a stainless steel autoclave and reacted at 140°C for 8 hours, followed by centrifugation, washing, and drying to obtain a catalyst precursor powder.

[0059] The catalyst precursor powder is placed in a tubular calcining furnace with sodium hypophosphite as a phosphorus source placed upstream and annealed and calcined at 350° C. for 2 h to obtain a transition metal phosphide powder;

[0060] The prepared transition metal phosphide powder is mixed with water, ethanol and Nafion solution, and ultrasonicated to obtain a uniformly dispersed suspension. The suspension is then coated on the surface of the cathode plate and the anode rod and air-dried for later use.

[0061] Compared with the above scheme, the specific operation process of synthesizing bifunctional catalysts has three steps:

[0062] (1) Hydrothermal synthesis of cobalt hydroxide precursor powder (Co(OH)2):

[0063] Accurately weigh 40 ml of deionized water using a graduated cylinder and pipette 1500 μl of 2 mol / L Co(NO3)2 solution;

[0064] Accurately weigh 0.36g of urea and 0.18g of ammonium fluoride and dissolve them in the above solution. Add a clean magnetic rod and stir for 10 minutes. Then remove the magnetic rod with a magnet. Transfer the mixed solution to a stainless steel reactor. After the reactor is covered with a cover, hydrothermal reaction is carried out at 140°C for 8 hours.

[0065] After the reaction is completed, use a clean small spoon to scrape the pink precipitate on the inner wall and bottom of the reactor, transfer the suspension containing the catalyst precursor to a 10ml centrifuge tube, centrifuge at 6000r / min for 5 minutes, pour out the supernatant in the centrifuge tube, rinse with deionized water and anhydrous ethanol three times respectively and repeat the above centrifugation operation. Finally, dry the catalyst precursor for use in the second step.

[0066] (2) Annealing and calcining to convert the above cobalt hydroxide into cobalt phosphide:

[0067] Accurately weigh 0.53 g of sodium hypophosphite and 0.28 g of the above-mentioned cobalt hydroxide powder, place the sodium hypophosphite and cobalt hydroxide upstream and downstream of the quartz boat respectively, and transfer them to the center of the tubular calcining furnace. Raise the temperature to 350°C at a heating rate of 2°C / min and anneal for 2 hours, then naturally cool to room temperature for use in the third step.

[0068] (3) Coating the catalyst powder onto the electrode surface:

[0069] Accurately measure 42 ml of deionized water and 22 ml of anhydrous ethanol with a measuring cylinder. First, accurately measure 5 ml of Nafion with a measuring cylinder and then use a pipette to measure 600 μL of Nafion solution. Mix the above cobalt phosphide powder and the adhesive solution and ultrasonicate for 30 minutes. After the ultrasonication, apply the cobalt phosphide suspension to the electrode surface to ensure that the loading on the electrode surface is 0.2 mg / cm 2 , then air dry for later use.

[0070] The remaining structures are the same as those of Example 1.

[0071] Example 3

[0072] Reference Figure 1 、 2 4 is the third embodiment of the present invention. This embodiment is different from the second embodiment in that it simultaneously treats sulfur-containing wastewater and formaldehyde.

[0073] During its use, the process of simultaneously treating sulfur-containing wastewater and formaldehyde is as follows:

[0074] Transporting wastewater to the anode and cathode areas;

[0075] Run the electrolysis equipment and perform oxidation and reduction reactions, while simultaneously detecting whether the exhaust gas meets the standards;

[0076] If the standards are met, discharge will take place;

[0077] If it does not meet the standards, it will be treated together with formaldehyde and waste gas;

[0078] The anode rod is then switched and the reaction is repeated, with the cycle returning to testing whether the exhaust gas meets the standards, until the liquid to be treated is processed and completed.

[0079] Compared with Example 2, the overall specific operation process is further as follows:

[0080] Open the first valve 401 and the fourth valve 405 to transport the sulfur-containing wastewater to the anode area 200 and the cathode area 300 respectively until all the anode rods 203 and cathode plates 301 are submerged;

[0081] Connect the constant voltage DC power supply 202, control the electrolysis voltage at 0.5-10V, and the anode area 200 continuously generates S 2- Oxidation reaction, the generated sulfur adheres to the surface of the anode rod 203; the cathode area 300 continues to generate H + The H2 produced by the reduction reaction is collected by the hydrogen recovery tank 303, and the by-product OH - Through OH -The selective permeable membrane 201 migrates toward the anode region 200;

[0082] After a period of electrolysis, the surface of the anode rod 203 is completely covered with sulfur. At this time, the paddle of the sliding switch mechanism 206 is toggled to switch to a different anode rod 203, and the reaction is repeated to continue to remove sulfur from the wastewater. 2- , and the sulfur covered in the working electrode before switching is - Polysulfides are generated under the action until they are completely dissolved and then used in the next electrolysis process;

[0083] To be S in the anode region 200 n 2- When the concentration is high enough, the second valve 402 is opened and the water pump 403 is started to transport the anolyte to the water distribution mechanism 103. At the same time, the exhaust gas containing formaldehyde is released through the gas distribution mechanism 106. The formaldehyde is oxidized into sodium formate, and S n 2- Restored to S 2- The exhaust gas continues to be oxidized at the anode, and passes through the exhaust gas detector 102. The exhaust gas that meets the standards is directly discharged into the atmosphere, and the exhaust gas that does not meet the standards is transported to the gas distribution mechanism 106 together with the formaldehyde waste gas;

[0084] Wait until S in the anode liquid 2- After the standards are met, the third valve 404 is opened to transport the anolyte to be treated out of the anode area 200, and waste acid is added to the anolyte to obtain sulfur and formic acid.

[0085] The remaining structures are the same as those of Example 2.

[0086] It is important to note that the construction and arrangement of the present application shown in a number of different exemplary embodiments are merely illustrative. Although only a few embodiments are described in detail in this disclosure, it should be readily understood by those who refer to this disclosure that many modifications are possible (e.g., the size, scale, structure, shape and proportion of various elements, as well as parameter values ​​(e.g., temperature, pressure, etc.), mounting arrangements, use of materials, color, directional changes, etc.) without departing substantially from the novel teachings and advantages of the subject matter described in this application. For example, an element shown as integrally formed may be composed of multiple parts or elements, the position of the element may be inverted or otherwise changed, and the nature or number or position of the discrete elements may be altered or changed. Therefore, all such modifications are intended to be included within the scope of the present invention. The order or sequence of any process or method steps may be changed or reordered according to alternative embodiments. In the claims, any "means plus function" clause is intended to cover the structure described herein that performs the function, and is not only structurally equivalent but also equivalent structures. Other replacements, modifications, changes, and omissions may be made in the design, operating conditions, and arrangement of the exemplary embodiments without departing from the scope of the present invention. Therefore, the invention is not limited to the specific embodiments, but extends to various modifications that still fall within the scope of the appended claims.

[0087] Additionally, in order to provide a concise description of exemplary embodiments, all features of an actual embodiment (ie, those features that are not relevant to the best mode presently contemplated for carrying out the invention or those that are not relevant to implementing the invention) may not be described.

[0088] It should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention and are not intended to limit the present invention. Although the present invention has been described in detail with reference to the preferred embodiments, those skilled in the art should understand that the technical solutions of the present invention may be modified or replaced by equivalents without departing from the spirit and scope of the technical solutions of the present invention, which should all be included in the scope of the claims of the present invention.

Claims

1. An integrated device for the simultaneous electrochemical treatment of sulfur-containing wastewater and formaldehyde, characterized by: The invention comprises a second valve (402), a water pump (403), and an electrolytic cell (F); the electrolytic cell (F) comprises an absorption region (100), an anode region (200), and a cathode region (300). The absorption region (100) is arranged above the anode region (200), and the anode region (200) is connected to one end of the cathode region (300); There is no partition between the absorption region (100) and the anode region (200), and the anode region (200) is connected to the OH - The selective permeable membrane (201) is separated from the cathode region (300); The absorption zone (100) includes an exhaust gas outlet (101) provided on an outer surface thereof, an exhaust gas detector (102) provided on the exhaust gas outlet (101), a water distribution mechanism (103) provided in the absorption zone (100), a packing mechanism (104) provided on a stainless steel packing support mesh plate (105) in the absorption zone (100) and located below the water distribution mechanism (103), and an air distribution mechanism (106) provided in the anode zone (200) and releasing exhaust gas to the packing mechanism (104), wherein the air distribution mechanism (106) is connected to the exhaust gas detector (102); and, The anode region (200) is connected to the cathode region (300) via a constant voltage DC power supply (202), and the constant voltage DC power supply (202) is connected to the anode region (200) via a sliding switch mechanism (206); The anode region (200) includes a plurality of anode rods (203) sequentially arranged therein, a first conductive metal rod (204) arranged at one end of the anode rod (203) and connected to the positive electrode of the constant voltage DC power supply (202), an anolyte inlet and outlet (205) arranged at one end of the anode region (200) and located below the anode rod (203), and a plane (207) arranged on the inner surface of the anode region (200); Anode area (200)S n 2- When the concentration is high enough, the second valve (402) is opened, and the water pump (403) is started to transport the anolyte to the water distribution mechanism (103). At the same time, the exhaust gas containing formaldehyde is released through the gas distribution mechanism (106). The formaldehyde is oxidized into sodium formate, and S n 2- Restored to S 2- The exhaust gas continues to be oxidized at the anode, and passes through the exhaust gas detector (102). The exhaust gas that meets the standards is directly discharged into the atmosphere, and the exhaust gas that does not meet the standards is transported to the gas distribution mechanism (106) together with the formaldehyde waste gas.

2. The integrated device for simultaneous electrochemical treatment of sulfur-containing wastewater and formaldehyde according to claim 1, characterized in that: The cathode region (300) includes a cathode plate (301) arranged inside the cathode region, a second conductive metal rod (302) arranged at one end of the cathode plate (301) and connected to the negative electrode of the constant voltage DC power supply (202), a hydrogen storage tank (303) arranged on the outer surface of the cathode region (300) and connected to its hydrogen outlet, a pressure gauge (304) arranged on the outer surface of the hydrogen storage tank (303), and a cathode liquid inlet (305) arranged at one end of the cathode region (300) and located below the cathode plate (301).

3. The integrated device for simultaneous electrochemical treatment of sulfur-containing wastewater and formaldehyde according to claim 2, characterized in that: The water distribution mechanism (103) comprises a water pipe (103a) fixed horizontally in the absorption zone (100), a plurality of nozzles (103b) arranged on the outer surface of the water pipe (103a), and nozzles (103c) arranged on the nozzles (103b). The nozzles (103b) are connected to the water pipe (103a) via threads.

4. The integrated device for simultaneous electrochemical treatment of sulfur-containing wastewater and formaldehyde according to claim 3, characterized in that: The gas distribution mechanism (106) adopts a stainless steel hollow rectangular parallelepiped structure, and a plurality of small holes are opened on the top thereof to facilitate gas release; The outer surfaces of the anode rod (203) and the cathode plate (301) are coated with a bifunctional catalyst.

5. The integrated device for simultaneous electrochemical treatment of sulfur-containing wastewater and formaldehyde according to any one of claims 2 to 4, characterized in that: The sliding switch mechanism (206) is a paddle, comprising a first copper sheet (206a) arranged on its outer surface, and a second copper sheet (206b) fixed to different anode ends of the sliding switch mechanism (206) and a third copper sheet (206c) at the power supply end, wherein the first copper sheet (206a) is in contact with the second copper sheet (206b) and the third copper sheet (206c) at the power supply end respectively connected to different anode electrodes, and the operation and stop of different anode rods (203) are controlled by toggling the paddle of the sliding switch mechanism (206); The cathode region (300) further includes a dryer (306) disposed on the outer surface of the hydrogen storage tank (303) and connected to the hydrogen outlet.

6. An integrated process for the simultaneous electrochemical treatment of sulfur-containing wastewater and formaldehyde, characterized by: The invention comprises the integrated device for the simultaneous electrochemical treatment of sulfur-containing wastewater and formaldehyde according to any one of claims 1 to 5, and also comprises a catalyst preparation method and a method for the simultaneous treatment of sulfur-containing wastewater and formaldehyde; The catalyst preparation method is as follows: Ammonium fluoride, urea, and one or two of ferric nitrate, nickel nitrate, and cobalt nitrate are dissolved in deionized water and introduced into a reactor for reaction to obtain a catalyst precursor powder; calcining the precursor powder; The calcined powder is mixed with water, ethanol and Nafion solution to obtain a suspension; Apply the suspension to the outer surface of the anode rod (203) and the cathode plate (301) and air dry; Among them, the method for simultaneously treating sulfur-containing wastewater and formaldehyde is as follows: Transporting wastewater to the anode and cathode areas; Run the electrolysis equipment and perform oxidation and reduction reactions, while simultaneously detecting whether the exhaust gas meets the standards; If the standards are met, discharge will take place; If it does not meet the standards, it will be treated together with formaldehyde and waste gas; The anode rod is then switched and the reaction is repeated, with the cycle returning to testing whether the exhaust gas meets the standards, until the liquid to be treated is processed and completed.

7. The integrated process for the simultaneous electrochemical treatment of sulfur-containing wastewater and formaldehyde according to claim 6, characterized in that: The catalyst preparation method is specifically as follows: Dissolving ammonium fluoride, urea, and one or more of ferric nitrate, nickel nitrate, and cobalt nitrate in deionized water to prepare a mixed solution; The mixed solution was added to a stainless steel autoclave and reacted at 140 °C for 8 h. The catalyst precursor powder was obtained by centrifugation, washing and drying. The catalyst precursor powder was placed in a tubular calcining furnace with sodium hypophosphite as a phosphorus source placed upstream and annealed at 350 °C for 2 h to obtain a transition metal phosphide powder. The prepared transition metal phosphide powder is mixed with water, ethanol and Nafion solution, and ultrasonically dispersed to obtain a uniformly dispersed suspension. The suspension is then coated on the surface of the cathode plate and the anode rod and air-dried for later use.

8. The integrated process for the simultaneous electrochemical treatment of sulfur-containing wastewater and formaldehyde according to claim 6 or 7, characterized in that: The method for simultaneously treating sulfur-containing wastewater and formaldehyde specifically adopts the following steps: Opening the first valve (401) and the fourth valve (405) to transport the sulfur-containing wastewater to the anode area (200) and the cathode area (300) respectively until all anode rods (203) and cathode plates (301) are submerged; Connect the constant voltage DC power supply (202), control the electrolysis voltage at 0.5-10 V, and the anode region (200) continuously generates S 2- Oxidation reaction, the generated sulfur adheres to the surface of the anode rod (203); the cathode area (300) continues to generate H + The H2 produced by the reduction reaction is collected by the hydrogen storage tank (303), and the by-product OH - Through OH - Migrate through the selective permeable membrane (201) toward the anode region (200); After a period of electrolysis, the surface of the anode rod (203) is completely covered with sulfur. At this time, the paddle of the sliding switch mechanism (206) is toggled to switch to a different anode rod (203), and the reaction is repeated to continue to remove sulfur from the wastewater. 2- , and the sulfur covered in the working electrode before switching is - Polysulfides are generated under the action until they are completely dissolved and then used in the next electrolysis process; Anode area (200)S n 2- When the concentration is high enough, the second valve (402) is opened, and the water pump (403) is started to transport the anolyte to the water distribution mechanism (103). At the same time, the exhaust gas containing formaldehyde is released through the gas distribution mechanism (106). The formaldehyde is oxidized into sodium formate, and S n 2- Restored to S 2- The exhaust gas continues to be oxidized at the anode, and passes through the exhaust gas detector (102). The exhaust gas that meets the standards is directly discharged into the atmosphere, and the exhaust gas that does not meet the standards is transported to the gas distribution mechanism (106) together with the formaldehyde waste gas. Wait until S in the anode liquid 2- After the standards are met, the third valve (404) is opened to transport the anolyte to be treated out of the anode area (200), and waste acid is added to the anolyte to obtain sulfur and formic acid.

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