System and method for electrolytic treatment of zinc chloride-containing organic waste liquid

Abstract

The invention discloses a system and method for electrolytic treatment of zinc chloride-containing organic waste liquid, and belongs to the technical field of chemical waste treatment, the system comprises an electrolytic bath, an anion exchange membrane is arranged in the electrolytic bath, and the electrolytic bath is divided into an electrolytic bath cathode part and an electrolytic bath anode part by the anion exchange membrane; a cathode and an anode are respectively arranged in the electrolytic tank cathode part and the electrolytic tank anode part and are connected through a direct-current power supply, the lower part of the electrolytic tank cathode part is connected with the electrolyte preparation tank through a circulating pipe and a circulating pump, and the upper end of the electrolyte preparation tank is connected with the electrolytic tank cathode part. The method provided by the invention realizes cyclic utilization of part of raw materials, has considerable economic value and environmental protection value, and is beneficial to green and sustainable development of fluorine-containing olefin production.

Description

Technical Field

[0001] This invention belongs to the field of chemical waste treatment technology, specifically relating to a system and method for electrolytically treating organic waste liquid containing zinc chloride. Background Technology

[0002] Fluorinated olefins are a class of chemical intermediates of significant industrial importance, typically prepared in organic solvents through the reaction of chlorofluorocarbon precursors with metal dechlorinating agents. The solvents used in the reaction are usually polar solvents, mainly divided into two categories: alcohol solvents and non-alcoholic polar solvents. Generally, simple fluorinated olefins such as trifluorochloroethylene and difluorodichloroethylene often use alcohols (such as methanol, ethanol, and isopropanol) as solvents. More complex fluorinated olefins such as perfluoromethyl vinyl ether, perfluorosulfonyl fluorinated vinyl ether, and 2,2,4-trifluoro-5-trifluoromethoxy-1,3-m-dioxane-pentene often use non-alcoholic polar solvents. Commonly used non-alcoholic polar solvents include amides (such as DMF and DMAc), nitriles (acetonitrile and propionitrile), as well as N-methylpyrrolidone, tetrahydrofuran, and dimethyl sulfoxide.

[0003] The common methods for separating and recovering zinc chloride in existing technologies include: hydrometallurgical zinc electrolysis, organic solvent extraction, molten salt electrolysis, and comprehensive waste utilization.

[0004] Electrolytic zinc smelting in hydrometallurgy: Common hydrometallurgical zinc refining processes use zinc sulfate or Zn(NH3)2Cl2 as raw materials, obtaining metallic zinc through electrolysis. Industrial production typically uses zinc sulfate electrolysis. There are fewer reports on the industrial electrolysis of zinc chloride. Chinese patent CN113584323A reports a method for obtaining metallic zinc by electrolysis using an aqueous solution of zinc chloride as a raw material; Chinese patent CN102453926A reports a method for obtaining high-purity zinc by electrolysis of zinc chloride, using an aqueous solution system to electrolyze zinc chloride to generate zinc and chlorine gas, achieving the recycling of zinc and chlorine. This method is only applicable to aqueous solutions of zinc chloride and cannot be used in organic solutions of zinc chloride.

[0005] Organic solvent extraction method: As described in patent US4631176A, an aqueous solution containing zinc chloride and impurities is extracted using an organic solvent, such as TBP, followed by back-extraction with an organic reagent immiscible with the extractant, such as methanol or ethylene glycol. Finally, zinc chloride is recovered by precipitating a zinc chloride-ammonia composition with the addition of ammonia or other ammonia donor. This method is suitable for recovering zinc chloride from aqueous systems containing zinc chloride.

[0006] Molten salt electrolysis: Unlike the electrolysis methods used in wet zinc smelting, molten salt electrolysis refers to electrolysis using anhydrous zinc chloride as a raw material. Chinese patent CN115747511A reports a method for treating zinc-containing flue gas from steel plants. This involves condensing the flue gas to obtain ZnCl2 and PbCl2; electrolyzing the obtained ZnCl2 to obtain metallic zinc and Cl2; and then reusing the Cl2 obtained from electrolysis in the chlorination smelting process to treat the zinc-containing flue gas from steel plants. Similarly, Japanese patent JP2014218697A also separates chlorine and zinc elements from zinc chloride in smelting converter dust through molten electrolysis. This method is suitable for separating metallic zinc from anhydrous zinc chloride. Its disadvantage is that maintaining the salt in a molten state requires very high temperatures, placing high demands on the equipment.

[0007] Comprehensive waste utilization method: This method involves treating zinc-containing waste, such as zinc-containing organic waste liquid and zinc-containing sludge, to recover zinc chloride and achieve comprehensive waste utilization. In the prior art, Chinese patent CN1299711A reports a method for treating trifluorochloroethylene production waste, using methanol as the solvent. After filtering and separating zinc powder, methanol is recovered by distillation, and zinc chloride and zinc powder are prepared into zinc oxide. However, this patent can only handle systems using methanol as the solvent. Chinese patent CN111333476A reports a method for treating fluorinated olefin production waste, particularly suitable for dechlorination systems using metallic zinc as the dechlorinating agent and non-alcoholic polar organic solvents as the solvent. This method involves several steps, including dissolving zinc chloride, solid-liquid separation, metathesis reaction, filtration, washing, drying, evaporation crystallization, and distillation. It comprehensively treats fluorinated olefin production waste using this method; however, this method has the disadvantages of too many processing steps and an excessively long process. Summary of the Invention

[0008] To address the aforementioned problems, this invention provides a system and method for electrolytically treating organic waste liquid containing zinc chloride. This system treats the waste liquid containing zinc chloride and organic solvents generated by the above reaction, solving the waste liquid discharge problem while realizing the recycling of some raw materials. It not only has considerable economic value but also environmental value, which is conducive to the green and sustainable development of fluoroolefin production.

[0009] The objective of this invention is achieved through the following technical solution: A system for electrolytically treating organic waste liquid containing zinc chloride includes an electrolytic cell. An anion exchange membrane is installed inside the electrolytic cell, dividing the electrolytic cell into a cathode section and an anode section. A cathode and an anode are respectively installed in the cathode section and the anode section. The cathode and anode are connected by a DC power supply. The lower part of the cathode section is connected to an electrolyte preparation tank through a circulation pipe and a circulation pump. The upper end of the electrolyte preparation tank is connected to the cathode section of the electrolytic cell.

[0010] Preferably, an anode cover is provided above the anode; the anode cover is provided with a chlorine gas exhaust port.

[0011] Preferably, the electrolytic cell is provided with multiple anion exchange membranes, which divide the electrolytic cell into multiple electrolytic cell cathode portions and electrolytic cell anode portions that are spaced apart from each other.

[0012] Preferably, the anode is a graphite or RuTi coated electrode; the cathode is aluminum or zinc.

[0013] Preferably, the anode and cathode are symmetrically arranged about the anion exchange membrane, and the distance between the anode and cathode is 10~100mm.

[0014] A method for electrolytically treating zinc chloride-containing organic waste liquid, wherein the zinc chloride-containing organic waste liquid is waste from the production of fluorinated olefins, and the fluorinated olefin production waste is the waste liquid obtained by reacting a chlorofluorocarbon precursor with a dechlorinating agent, metallic zinc, in a non-alcoholic polar solvent to prepare fluorinated olefins, comprising the following steps: Step 1: Add the same organic solvent to the organic waste liquid containing zinc chloride. The type of organic solvent is the same as the solution used in the previous dechlorination reaction. Filter the zinc powder to obtain the zinc chloride organic solution. The initial concentration of zinc chloride is 80~160g / L. Add it to the cathode part of the electrolytic cell. Step 2: Prepare a saturated sodium chloride solution and add it to the anode section of the electrolytic cell; Step 3: Turn on the DC power supply and begin electrolysis. Control the electrolysis temperature between 20℃ and 90℃, and the cathode current density between 300 and 1500 A / m. 2 Zinc and chlorine gas are obtained at the cathode and anode, respectively; Step 4: After electrolysis stops, the zinc produced at and below the cathode is collected, and the chlorine produced at the anode is passed to the subsequent chlorine absorption device for treatment. Finally, the remaining organic solvent at the cathode is recycled.

[0015] Preferably, in step one, the organic solution is a mixture of one or more of N,N-dimethylformamide, N,N-dimethylacetamide, dimethyl sulfoxide, N-methylpyrrolidone, and tetrahydrofuran in any proportion.

[0016] Preferably, in step three, electrolysis begins with a small current, which is gradually increased to the operating current.

[0017] Preferably, in step three, when the operating current is increased, the cathode current density is controlled at 300~1500 A / m. 2 .

[0018] Preferably, in step four, electrolysis can be stopped at any time according to electrolysis requirements; or electrolysis can be stopped when the zinc chloride concentration is lower than 10 g / L; or zinc chloride can be added to the electrolyte preparation tank and the zinc chloride can be replenished to the cathode part of the electrolytic cell by a circulating pump to maintain the concentration, and then stopped after a certain period of time.

[0019] The beneficial effects of this technical solution are as follows: I. This invention provides a system for electrolytically treating organic waste liquid containing zinc chloride, achieving the separation of zinc and chlorine elements in zinc chloride. The cathode of the electrolytic cell is filled with waste liquid containing zinc chloride and organic solvents, while the anode is filled with a saturated sodium chloride solution. An anion exchange membrane separates the cathode and anode, avoiding side reactions between chlorine and zinc. After electrolysis, chlorine gas is generated at the anode, and metallic zinc is generated at the cathode. The zinc and solvent can be recycled, and the generated chlorine gas is treated by alkaline washing.

[0020] II. The present invention provides a system for electrolytically treating organic waste liquid containing zinc chloride. After electrolysis, chlorine gas is generated at the anode and metallic zinc is generated at the cathode. The zinc and solvent after electrolysis can be recycled and reused. The generated chlorine gas is treated by alkaline washing. All components in the waste liquid, including chlorine, zinc and solvent, are recovered or treated.

[0021] III. This invention provides a method for electrolytically treating organic wastewater containing zinc chloride, achieving the separation of chlorine and zinc in zinc chloride and realizing the recycling of organic solvents and zinc. It solves the wastewater discharge problem while recovering some raw materials, possessing high economic and environmental value. Compared with existing technologies, this invention requires less equipment, involves fewer steps, and has a shorter process, making it highly practical. Attached Figure Description

[0022] Figure 1 This is a schematic diagram of the structure of the present invention; The components are: 1. Anode; 2. Anode cover; 3. DC power supply; 4. Cathode; 5. Cathode section of electrolytic cell; 6. Electrolyte preparation tank; 7. Circulation pump; 8. Anion exchange membrane; 9. Anode section of electrolytic cell; 10. Electrolytic cell. Detailed Implementation

[0023] The present invention will be further described in detail below with reference to embodiments, but the implementation of the present invention is not limited thereto.

[0024] like Figure 1As shown, a system for electrolytically treating organic waste liquid containing zinc chloride includes an electrolytic cell 10. An anion exchange membrane 8 is installed inside the electrolytic cell 10, dividing it into a cathode portion 5 and an anode portion 9. A cathode 4 and an anode 1 are respectively installed in the cathode portion 5 and the anode portion 9. The cathode 4 and anode 1 are connected via a DC power supply 3. The lower part of the cathode portion 5 is connected to an electrolyte preparation tank 6 via a circulation pipe and a circulation pump 7. The upper end of the electrolyte preparation tank 6 is connected to the cathode portion 5. The electrolytic cell 10 is made of glass or plastic and is resistant to acid and chlorine corrosion.

[0025] An anode cover 2 is provided above the anode 1; a chlorine gas outlet is provided on the anode cover 2.

[0026] The electrolytic cell 10 is provided with multiple anion exchange membranes 8, which divide the electrolytic cell 10 into multiple electrolytic cell cathode portions 5 and electrolytic cell anode portions 9 that are spaced apart from each other.

[0027] The anode 1 is a graphite or RuTi coated electrode; the cathode 4 is aluminum or zinc.

[0028] The anode 1 and cathode 4 are symmetrically arranged about the anion exchange membrane 8, and the distance between the anode 1 and cathode 4 is 10~100mm.

[0029] The electrode reaction for the electrolysis of zinc chloride in this system is as follows: Cathode: Zn 2+ +2e - =Zn; Anode: 2Cl - -2e - =Cl2.

[0030] A method for electrolytically treating zinc chloride-containing organic waste liquid, wherein the zinc chloride-containing organic waste liquid is waste from the production of fluorinated olefins, and the fluorinated olefin production waste is the waste liquid obtained by reacting a chlorofluorocarbon precursor with a dechlorinating agent, metallic zinc, in a non-alcoholic polar solvent to prepare fluorinated olefins, comprising the following steps: Step 1: Add the same organic solvent to the organic waste liquid containing zinc chloride. The type of organic solvent is the same as the solution used in the previous dechlorination reaction. Filter the zinc powder to obtain the zinc chloride organic solution. The initial concentration of zinc chloride is 80~160g / L. Add it to the cathode part 5 of the electrolytic cell. Step 2: Prepare a saturated sodium chloride solution and add it to the anode section 9 of the electrolytic cell; Step 3: Start DC power supply 3 and begin electrolysis. Control the electrolysis temperature at 20℃~90℃ and the cathode current density at 300~1500A / m2. Zinc and chlorine gas are obtained at cathode 4 and anode 1, respectively. Step 4: After electrolysis stops, the zinc produced at cathode 4 and below cathode 4 is collected, and the chlorine produced at anode 1 is passed to the subsequent chlorine absorption device for treatment. Finally, the remaining organic solvent at cathode 4 is recycled.

[0031] In step one, the organic solution is a mixture of one or more of N,N-dimethylformamide, N,N-dimethylacetamide, dimethyl sulfoxide, N-methylpyrrolidone, and tetrahydrofuran in any proportion.

[0032] In step three, electrolysis begins, with a small current used at the start and the current gradually increased to the operating current.

[0033] In step three, when the operating current is increased, the current density of cathode 4 is controlled between 300 and 1500 A / m. 2 .

[0034] In step four, electrolysis is stopped when the zinc chloride concentration in the cathode section 5 of the electrolytic cell falls below 10 g / L.

[0035] Fluoroolefin production waste is the waste liquid obtained by reacting chlorofluorocarbon precursors with zinc as a dechlorinating agent in a non-alcoholic polar solvent to prepare fluoroolefins. Its composition is unknown and requires various detection methods to determine. This study uses a prepared zinc chloride-containing organic waste liquid to verify the effectiveness of an electrolytic treatment method for this waste liquid.

[0036] The method for preparing the zinc chloride-containing organic waste liquid is as follows: Add 325-mesh zinc powder and organic solvent to a four-necked flask equipped with a mechanical stirrer, a constant-pressure feeding funnel, a reflux condenser, and a thermometer tube. Add 98.5% pure 4,5-dichloro-2,2,4-trifluoro-5-trifluoromethoxy-1,3-dioxane to the constant-pressure funnel. Start stirring and heating. Once the internal temperature reaches 80℃, begin dropwise addition, controlling the internal temperature at 80-85℃ during the dropwise addition. After the dropwise addition is complete, continue stirring at 80℃ for 1 hour. The reaction equation is as follows: The product 2,2,4-trifluoro-5-trifluoromethoxy-1,3-m-dioxane was collected using an ice-water cooling trap. After the reaction was completed, the residue was obtained, which consisted of organic solvent, zinc powder, and zinc chloride.

[0037] There are various methods for preparing organic waste liquid containing zinc chloride. The method described above is just one of them. Similar methods include the dechlorination reaction of chlorofluorocarbons containing ortho-chlorine, such as 1,1,2-trichlorotrifluoroethane, which can also produce similar organic waste liquid containing zinc chloride. In other words, organic waste liquid containing zinc chloride is composed of organic solvent, zinc powder and zinc chloride.

[0038] Example 1 This embodiment uses the aforementioned system for electrolytic treatment of zinc chloride-containing organic waste liquid to electrolyze the prepared zinc chloride-containing organic waste liquid. The residue in the reactor is 1135g, and its composition is 70.5wt% N,N-dimethylformamide (DMF), 9.3wt% zinc powder, and 20.2wt% zinc chloride. 200g of DMF is added, and the zinc powder is removed by filtration, yielding 990g of a zinc chloride DMF solution with a zinc ion concentration of 110g / L.

[0039] like Figure 1 As shown, the self-made electrolytic cell 10 has a total volume of 700ml, with 350ml each for the anode section 9 and the cathode section 5. 990g of zinc chloride DMF solution with a zinc ion concentration of 110g / L is added to the electrolyte preparation tank 6, with 300g of the solution being added to the cathode section 5 via a circulation pump 7. 123g of sodium chloride is added to a beaker, along with 219g of deionized water, and stirred to dissolve, preparing a saturated sodium chloride solution of 342g. This solution is then added to the anode section 9. The anode 1 uses a 35mm × 50mm Ru-Ti coated anode, and the cathode 4 uses a 35mm × 50mm zinc plate. The distance between the cathode 4 and the anode 1 is controlled at 40mm. Electrolysis is performed with a 1A DC current, corresponding to a current density of 570A / m. 2 The electrolysis temperature was 40~60℃. After 2 hours of energizing, 1.17g of zinc product was collected at the cathode, corresponding to a current efficiency of 48%.

[0040] Example 2 The difference between this embodiment and Embodiment 1 is that: 1000g of residue was collected from the reactor, and the residue consisted of 55wt% N,N-dimethylacetamide (DMAC), 12wt% zinc powder, and 33wt% zinc chloride. 600g of DMAC was added, and the zinc powder was removed by filtration, resulting in a zinc chloride DMF solution with a zinc ion concentration of 120g / L.

[0041] A zinc chloride DMF solution with a zinc ion concentration of 120 g / L was added to electrolyte preparation tank 6. 300 g of this solution was then pumped into the cathode section 5 of the electrolytic cell via a circulating pump 7. 113 g of sodium chloride was added to a beaker, and 202 g of deionized water was added and stirred to dissolve, preparing a saturated sodium chloride solution of 315 g. This solution was then added to the anode section 9 of the electrolytic cell. Electrolysis was performed by applying a 1 A DC current, corresponding to a current density of 570 A / m. 2 The electrolysis temperature was 40~60℃. After 2 hours of energizing, 1.17g of zinc product was collected at the cathode, corresponding to a current efficiency of 48%.

[0042] Example 3 The difference between this embodiment and Embodiment 1 is as follows: 1000g of residual material from the reactor, composed of 62wt% tetrahydrofuran (THF), 8wt% zinc powder, and 28wt% zinc chloride, is added to a beaker. 570g of THF is added and stirred to dissolve, preparing a zinc chloride THF solution with a zinc ion concentration of 100g / L. After filtering to remove the zinc powder, the solution is added to the electrolyte preparation tank 6. 300g of this solution is then added to the cathode section 5 of the electrolytic cell via a circulation pump 7. 103g of sodium chloride is added to a beaker, and 184g of deionized water is added and stirred to dissolve, preparing a saturated sodium chloride solution of 287g. This solution is then added to the anode section 9 of the electrolytic cell. The distance between the cathode 4 and anode 1 is controlled at 30mm, and electrolysis is performed using a 1.2A DC current, corresponding to a current density of 685A / m. 2 The electrolysis temperature was 25~45℃. After 4 hours of energizing, 4.47g of zinc was collected from the cathode, with a current efficiency of 76%.

[0043] Example 4 The difference between this embodiment and Embodiment 2 is that a dimethyl sulfoxide (DMSO) zinc chloride solution, which has undergone a dissolution and filtration process, is added to the cathode portion 5 of the electrolytic cell, with a zinc ion concentration of 85 g / L. A saturated sodium chloride solution is added to the anode portion 9 of the electrolytic cell, and electrolysis is performed by passing a 1 A DC current, corresponding to a current density of 570 A / m. 2 The electrolysis temperature was 40~70℃. After 2 hours of energizing, 2.05g of zinc was collected from the cathode, with a current efficiency of 84%.

[0044] Example 5 The difference between this embodiment and Embodiment 2 is that, in the cathode section 5 of the electrolytic cell, an N-methylpyrrolidone (NMP) zinc chloride solution that has undergone a dissolution and filtration process is added, with a zinc ion concentration of 120 g / L; in the anode section 9 of the electrolytic cell, a saturated sodium chloride solution is added, and electrolysis is performed by passing a 2 A DC current, corresponding to a current density of 1140 A / m. 2 The electrolysis temperature was 30~50℃. After 3 hours of energizing, 6.65g of zinc was collected from the cathode, with a current efficiency of 90%.

[0045] Example 6 The difference between this embodiment and Embodiment 1 is that: 1000g of residue was collected from the reactor, and the residue consisted of 72wt% N,N-didimethyl sulfoxide (DMSO), 12wt% zinc powder, and 16wt% zinc chloride. 150g of DMSO was added, and the zinc powder was removed by filtration, resulting in a zinc chloride DMSO solution with a zinc ion concentration of 60g / L.

[0046] A zinc chloride DMSO solution with a zinc ion concentration of 60 g / L is added to electrolyte preparation tank 6. 300 g of this solution is then pumped into the cathode section 5 of the electrolytic cell via a circulating pump 7. 103 g of sodium chloride is added to a beaker, along with 184 g of deionized water, and stirred to dissolve, preparing a saturated sodium chloride solution of 287 g. This solution is then added to the anode section 9 of the electrolytic cell. The distance between cathode 4 and anode 1 is controlled at 10 mm. Electrolysis is performed using a 0.5 A DC current, corresponding to a current density of 300 A / m. 2 The electrolysis temperature was 20~40℃. After 2 hours of energizing, 0.87g of zinc product was collected at the cathode, corresponding to a current efficiency of 71%.

[0047] Example 7 The difference between this embodiment and Example 1 is as follows: 1000g of residue was collected from the reactor. The residue consisted of 32wt% N-methylpyrrolidone (NMP), 32wt% tetrahydrofuran (THF), 8wt% zinc powder, and 28wt% zinc chloride. 90g of NMP and 90g of THF were added, and the zinc powder was removed by filtration, resulting in a zinc chloride NMP-THF solution with a zinc ion concentration of 160g / L.

[0048] A zinc chloride NMP-THF solution with a zinc ion concentration of 160 g / L was added to electrolyte preparation tank 6. 300 g of this solution was then pumped into the cathode section 5 of the electrolytic cell via a circulation pump 7. 112 g of sodium chloride was added to a beaker, along with 201 g of deionized water, and stirred to dissolve, preparing a saturated sodium chloride solution of 313 g. This solution was then added to the anode section 9 of the electrolytic cell. The distance between cathode 4 and anode 1 was controlled at 100 mm. Electrolysis was performed using a 2.6 A DC current, corresponding to a current density of 1500 A / m. 2 The electrolysis temperature was 60~90℃. After 2 hours of electrolysis, 2.24g of zinc product was collected at the cathode, corresponding to a current efficiency of 35%.

[0049] Comparative Example 1 The difference between this comparative example and Example 1 is that the electrolysis using 0.5A DC corresponds to a current density of 285A / m. 2 After energizing for 2 hours, 0.59 g of zinc product was collected at the cathode, corresponding to a current efficiency of 49%. Compared with Example 1, the zinc product collected at the cathode in this comparative example was significantly reduced.

[0050] Comparative Example 2 The difference between this comparative example and Example 1 is that the electrolysis is performed with a 3A DC current, corresponding to a current density of 1710A / m. 2 After 2 hours of energization, 3.07 g of zinc was collected at the cathode, corresponding to a current efficiency of 42%. This comparative example, due to its higher current density, generates a large amount of heat during water electrolysis. To maintain the electrolysis temperature at 40-60°C, an additional heat exchange and cooling device is required, increasing operating costs. Compared to Example 1, this comparative example shows a significant reduction in the amount of zinc collected at the cathode. The current density needs to be controlled to be less than 1500 A / m.2 .

[0051] Comparative Example 3 The difference between this comparative example and Example 2 is that the distance between the anode 1 and the cathode 4 is controlled at 110 mm, and electrolysis is performed with a 2A DC current, corresponding to a current density of 1140 A / m. 2 The electrolysis temperature was 30-50℃. After 3 hours of energization, 0.88g of zinc was collected from the cathode, with a current efficiency of 12%. Compared to Example 2, the current efficiency of this comparative example decreased significantly after the distance between anode 1 and cathode 4 was increased. In this comparative example, the large distance between the anode and cathode resulted in high system resistance, low current efficiency, and high heat generation, requiring an additional heat exchange and cooling device. Compared to Example 2, the amount of zinc collected from the cathode was significantly reduced. The distance between the anode and cathode needs to be controlled to be less than 100mm.

[0052] Comparative Example 4 The difference between this comparative example and Example 2 is that the distance between the anode 1 and the cathode 4 is controlled at 110 mm, and electrolysis is performed with a DC current of 0.5 A, corresponding to a current density of 285 A / m. 2 The electrolysis temperature was 30-50℃. After 3 hours of energization, 0.49g of zinc product was collected from the cathode, with a current efficiency of 20%. Compared with Example 2, the current efficiency of this comparative example decreased significantly after the distance between anode 1 and cathode 4 was increased. Due to the large distance between the anode and cathode, this comparative example resulted in high system resistance, low current efficiency, and large heat release, requiring an additional heat exchange and cooling device.

[0053] Comparative Example 5 The difference between this comparative example and Example 3 is that, in the zinc chloride THF solution with a zinc ion concentration of 50 g / L, after 4 hours of electrolysis, 3.88 g of zinc was collected at the cathode, with a current efficiency of 66%. Compared with Example 3, this comparative example shows that the higher the zinc ion concentration in the zinc chloride organic solvent solution, the higher the zinc collected at the cathode and the higher the current efficiency.

[0054] Comparative Example 6 The difference between this comparative example and Example 3 is that, in the zinc chloride THF solution with a zinc ion concentration of 170 g / L, after 4 hours of electrolysis, 5.59 g of zinc was collected at the cathode, with a current efficiency of 95%. Compared with Example 3, this comparative example shows that in the zinc chloride organic solvent solution, the higher the zinc ion concentration, the higher the cathode collection product zinc and the higher the current efficiency; however, due to the limitation of solubility, the solubility cannot be increased indefinitely, and the cost and effect of increasing the zinc ion concentration are not proportional.

[0055] Comparative Example 7 The difference between this comparative example and Example 4 is that the electrolysis temperature was 92~95℃, and after 2 hours of energization, 2.15g of zinc was collected from the cathode, with a current efficiency of 88%. Compared with Example 4, the higher the electrolysis temperature, the higher the zinc collected from the cathode and the higher the current efficiency. However, if the electrolysis temperature is too high, exceeding the maximum operating temperature of the ion exchange membrane, it will reduce the membrane's lifespan or cause damage. Therefore, the electrolysis temperature needs to be controlled below 90℃.

[0056] Comparative Example 8 The difference between this comparative example and Example 4 is that the electrolysis temperature was 10~20℃, and after 2 hours of energization, 1.07g of zinc was collected from the cathode, with a current efficiency of 44%. Compared with Example 4, the electrolysis temperature in this comparative example is lower, which is not conducive to the production of zinc collected from the cathode, and the current efficiency is also lower.

[0057] Experimental Example 1 The reaction performance of zinc powder recovery was verified by using the reaction of CF3OCFCl-CF2Cl with zinc powder.

[0058] 100g of DMF and 40g of recovered zinc powder were added to a four-necked glass reaction flask equipped with a stirrer, feeding funnel, reflux condenser and thermometer. The water bath temperature was set to 70℃. 98.5g of CF3OCFCl-CF2Cl with a purity of 87.0% was slowly added dropwise to the flask through a constant pressure funnel. After the reaction was completed, 65g of product was collected in a dry ice-alcohol cold trap. GC analysis showed that the CF3OCF=CF2 content was 87.6% and the reaction yield was 95.0%.

[0059] Experiment Example 2 The reaction performance of the recovered solvent was verified by the reaction of CF3OCFCl-CF2Cl with zinc powder.

[0060] 40g of zinc powder and 140g of DMF zinc chloride solution recovered from electrolysis were added to a four-necked glass reaction flask equipped with a stirrer, feeding funnel, reflux condenser and thermometer. The zinc ion concentration was 38g / L. The water bath temperature was set to 70℃. 96g of CF3OCFCl-CF2Cl with a purity of 90.0% was slowly added dropwise to the flask through a constant pressure funnel. After the reaction was completed, 66.8g of product was collected in a dry ice-alcohol cold trap. GC analysis showed that the CF3OCF=CF2 content was 87.4%, and the reaction yield was 96.6%.

[0061] Experimental Example 3 The reaction of CF3OCFCl-CF2Cl with zinc powder was performed using fresh zinc powder and a fresh solvent. The reaction performance was compared with that of the reaction using recycled zinc powder and a recycled solvent to verify its reactivity.

[0062] 40g of zinc powder and 100g of DMF were added to a four-necked glass reaction flask equipped with a stirrer, a feeding funnel, a reflux condenser, and a thermometer. The water bath temperature was set to 70℃. 95g of CF3OCFCl-CF2Cl with a purity of 90.0% was slowly added dropwise to the flask through a constant pressure funnel. After the reaction was completed, 64.2g of product was collected in a dry ice-alcohol cold trap. GC analysis showed that the CF3OCF=CF2 content was 89.2%, and the reaction yield was 95.6%.

[0063] The above description is merely a preferred embodiment of the present invention and is not intended to limit the present invention in any way. Any simple modifications or equivalent changes made to the above embodiments based on the technical essence of the present invention are within the protection scope of the present invention.

Claims

1. A system for electrolytically treating organic waste liquids containing zinc chloride, characterized in that: The application relates to an electrolytic tank (10) provided with an anion exchange membrane (8), which divides the electrolytic tank (10) into an electrolytic tank cathode part (5) and an electrolytic tank anode part (9), the electrolytic tank cathode part (5) and the electrolytic tank anode part (9) are respectively provided with a cathode (4) and an anode (1), the cathode (4) and the anode (1) are connected through a direct-current power supply (3), the lower part of the electrolytic tank cathode part (5) is connected with an electrolyte preparation tank (6) through a circulating pipe and a circulating pump (7), and the upper end of the electrolyte preparation tank (6) is connected with the electrolytic tank cathode part (5).

2. A system for electrolytically treating chlorinated zinc-containing organic effluent according to claim 1, characterized in that: An anode cover (2) is arranged above the anode (1); and a chlorine gas discharge port is arranged on the anode cover (2).

3. A system for electrolytically treating organic waste liquids containing zinc chloride according to claim 1, characterized in that: A plurality of anion exchange membranes (8) are arranged in the electrolytic tank (10) and divide the electrolytic tank (10) into a plurality of electrolytic tank cathode parts (5) and electrolytic tank anode parts (9) which are arranged at intervals.

4. A system for electrolytically treating organic waste liquids containing zinc chloride according to claim 1, characterized in that: The anode (1) is a graphite or RuTi coating electrode; and the cathode (4) is aluminum or zinc.

5. A system for electrolytically treating chlorinated zinc-containing organic waste liquid according to claim 1, characterized in that: The anode (1) and the cathode (4) are symmetrically arranged relative to the anion exchange membrane (8), and the distance between the anode (1) and the cathode (4) is 10-100 mm.

6. A method of electrolytically treating a chlorozincate-containing organic waste solution, said chlorozincate-containing organic waste solution being a fluoroolefin production waste solution, the fluoroolefin production waste solution being a waste solution obtained by reacting a fluoro-chloroalkane precursor with a dechlorination agent, metallic zinc, in a non-alcoholic polar solvent, to produce a fluoroolefin, characterized in that, The application further discloses a preparation method of the electrolytic tank. Step one: adding the same organic solvent into the chlorozincic organic waste liquid, filtering zinc powder to obtain a chlorozincic organic solution, the initial concentration of the chlorozincic organic solution is 80-160 g / L, and the chlorozincic organic solution is added into the electrolytic tank cathode part (5); Step two: adding a saturated sodium chloride solution into the electrolytic tank anode part (9); Step three, start the direct current power supply (3), start electrolysis, electrolysis temperature control in 20℃~90℃, cathode (4) current density control in 300~1500A / m 2 Zinc and chlorine gas are obtained at the cathode (4) and anode (1), respectively; Step four: after electrolysis is stopped, zinc generated by the cathode (4) and the cathode (4) below is collected, chlorine generated by the anode (1) is led to a subsequent chlorine absorption device for treatment, and finally the residual organic solvent of the cathode (4) is recycled.

7. A method of electrolytically treating chlorinated zinc-containing organic effluent as claimed in claim 6, characterised in that: In the step one, the organic solution is a mixed solvent of one or more of N, N-dimethylformamide, N, N-dimethylacetamide, dimethyl sulfoxide, N-methyl pyrrolidone and tetrahydrofuran in any proportion.

8. A method of electrolytically treating chlorinated zinc-containing organic effluent as claimed in claim 6, characterised in that: In the step three, electrolysis is started, a small current is adopted at the start of electrolysis, and the current is gradually increased to an operating current.

9. A method of electrolytically treating chlorinated zinc-containing organic effluent as claimed in claim 8, characterised in that: In the third step, the cathode (4) current density is controlled at 300-1500 A / m when the operating current is raised 2 .

10. A method of electrolytically treating chlorinated zinc-containing organic waste liquid according to claim 6, characterized in that: In the step four, electrolysis can be stopped at any time according to electrolysis requirements, or electrolysis is stopped when the concentration of chlorozincic is lower than 10 g / L, or electrolysis is stopped after a certain time when chlorozincic is supplemented in the electrolyte preparation tank (6) and the circulating pump (7) is used to supplement chlorozincic in the electrolytic tank cathode part (5) to maintain the concentration.

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