Cyclic preparation method of potassium iodide
By adding precipitant and evaporation and concentration steps to the redox reaction system, the problem of low utilization rate of raw materials in the preparation of potassium iodide is solved, and the recycling of raw materials and the improvement of product purity is achieved.
Patent Information
- Application Number
- CN202510394052.X
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2025-03-31
- Publication Date
- 2025-07-01
AI Technical Summary
The preparation method of potassium iodide in the prior art is not conducive to improving the utilization rate of raw materials.
A redox reaction is carried out in a redox reaction system containing elemental iodine, potassium hydroxide and potassium formate. A precipitant reaction is added to perform the precipitation reaction. Through evaporation, concentration and cooling of the crystallization steps, potassium iodide is formed and the mother liquor is recovered to realize the recycling of raw materials.
The utilization rate of raw materials is improved, the loss of solid impurities and evaporated solvents is reduced, and the purity and yield of potassium iodide is improved.
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Abstract
Description
Technical Field
[0001] The present application relates to the technical field of potassium iodide preparation, and particularly to a cyclic preparation method of potassium iodide. Background Art
[0002] Potassium iodide is an important chemical raw material and can be widely used in the pharmaceutical and chemical industries. In the pharmaceutical field, potassium iodide can be used to prevent and treat iodine-deficiency goiter, and using its antifungal activity, it can be clinically used to treat sporotrichosis, chromoblastomycosis, persistent nodular erythema, nodular vasculitis, etc.; in the chemical field, potassium iodide can be used to prepare iodides, synthesize organic dyes, can be used as a photographic sensitizing emulsifier, a co-solvent for iodine and certain sparingly soluble metal iodides, and can also be used for chromatographic analysis and spot pain analysis, and can be used to prepare an iodine-potassium iodide-water etching solution for wet etching of chips.
[0003] Currently, the preparation method of potassium iodide is not conducive to improving the utilization rate of raw materials. Summary of the Invention
[0004] Based on this, the present application provides a cyclic preparation method of potassium iodide to solve the technical problem in the prior art that is not conducive to improving the utilization rate of raw materials.
[0005] The embodiments of the present application provide a cyclic preparation method of potassium iodide, including:
[0006] Performing a redox reaction at a first temperature in a redox reaction system containing elemental iodine, potassium hydroxide, and potassium formate to obtain a redox reaction solution;
[0007] Adding a precipitant to the redox reaction solution, performing a precipitation reaction at a second temperature, and subjecting the obtained reaction solution to solid-liquid separation to obtain a potassium iodide solution;
[0008] Evaporating and concentrating the potassium iodide solution to obtain a potassium iodide evaporation concentrate, subjecting the potassium iodide evaporation concentrate to cooling crystallization and solid-liquid separation to respectively obtain potassium iodide crystals and a potassium iodide mother liquor, and adding the potassium iodide mother liquor to the redox reaction system.
[0009] In some embodiments, adding the potassium iodide mother liquor to the redox reaction system includes:
[0010] Mixing crude iodine containing elemental iodine, the potassium iodide mother liquor, and a first solvent to obtain an iodine-containing aqueous solution;
[0011] Mixing potassium hydroxide, potassium formate, and a second solvent to obtain a reducing solution;
[0012] Adding the reducing solution to the iodine-containing aqueous solution to obtain the redox reaction system.
[0013] In some embodiments, the iodine-containing aqueous solution comprises 1 part by mass of elemental iodine, 2.5 to 3.5 parts by mass of potassium iodide mother liquor, and 1.5 to 2.5 parts by mass of a first solvent.
[0014] In some embodiments, in the redox reaction system, the molar ratio of potassium hydroxide to potassium formate is 0.5 to 1.
[0015] In some embodiments, in the redox reaction system, the molar ratio of iodine element to formate is 0.9 to 1.1.
[0016] In some embodiments, the first temperature is 60°C to 85°C.
[0017] In some embodiments, the method for recycling the preparation of potassium iodide further comprises:
[0018] Centrifuging the potassium iodide crystals to remove the moisture in the potassium iodide crystals.
[0019] In some embodiments, the precipitating agent is potassium hydroxide, the second temperature is 70 to 90°C, and the pH value of the precipitation reaction is 8 to 10.
[0020] In some embodiments, adding a precipitating agent to the redox reaction solution includes:
[0021] Adding a potassium hydroxide solution with a mass percentage of 20% to 50% to the redox reaction solution.
[0022] In some embodiments, the method for recycling the preparation of potassium iodide further comprises:
[0023] Performing solid-liquid separation on the redox reaction solution to remove solid impurities.
[0024] The cyclic preparation method of potassium iodide according to the embodiments of the present application includes performing a redox reaction at a first temperature in a redox reaction system containing elemental iodine, potassium hydroxide, and potassium formate to obtain a redox reaction solution; adding a precipitating agent to the redox reaction solution, performing a precipitation reaction at a second temperature, and subjecting the obtained reaction solution to solid-liquid separation to obtain a potassium iodide solution; evaporating and concentrating the potassium iodide solution to obtain a potassium iodide evaporation concentrate, cooling and crystallizing the potassium iodide evaporation concentrate and performing solid-liquid separation to obtain potassium iodide crystals and a potassium iodide mother liquor respectively, and adding the potassium iodide mother liquor to the redox reaction system; in the above manner, potassium iodide is formed by a redox method, and potassium iodide can be obtained by performing a single reaction in a reaction system. Subsequently, impurities are removed by using a precipitating agent. Only solid impurities and the solvent evaporated in the evaporation and concentration step leave the reaction system during the entire reaction process, realizing the recycling of raw materials and being beneficial to improving the utilization rate of raw materials. BRIEF DESCRIPTION OF THE DRAWINGS
[0025] Figure 1 FIG. is a schematic flow chart of the cyclic preparation method of potassium iodide according to an embodiment of the present application. DETAILED DESCRIPTION OF THE EMBODIMENTS
[0026] To facilitate the understanding of the present application, the present application will be described more comprehensively below with reference to the relevant drawings. The preferred embodiments of the present application are shown in the drawings. However, the present application can be implemented in many different forms and is not limited to the embodiments described herein. On the contrary, the purpose of providing these embodiments is to make the understanding of the disclosure of the present application more thorough and comprehensive.
[0027] It should be noted that when an element is referred to as being "fixed to" another element, it can be directly on the other element or there can also be an intermediate element. When an element is considered to be "connected" to another element, it can be directly connected to the other element or there may be an intermediate element at the same time.
[0028] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by those skilled in the technical field to which the present application belongs. The terms used in the specification of the present application herein are only for the purpose of describing specific embodiments and are not intended to limit the present application.
[0029] As Figure 1 shown, it is a cyclic preparation method of potassium iodide according to an embodiment of the present application.
[0030] As Figure 1 shown, the cyclic preparation method of potassium iodide includes the steps:
[0031] (1) Redox step: performing a redox reaction at a first temperature in a redox reaction system containing elemental iodine, potassium hydroxide and potassium formate to obtain a redox reaction solution.
[0032] Among them, elemental iodine, potassium hydroxide and potassium formate are present in the redox reaction system. Potassium hydroxide is alkaline in aqueous solution, and potassium formate is alkaline in aqueous solution. Therefore, the redox reaction system is alkaline, and the redox reaction can be carried out under alkaline conditions.
[0033] During the redox reaction, two pathways of reaction occur simultaneously.
[0034] In the first reaction path, when elemental iodine encounters potassium formate, due to its strong oxidizing property, it will seize electrons from the formate ion, and the elemental iodine will be reduced to iodide ions by the formate ion to obtain potassium iodide. At the same time, after the formate ion is oxidized and loses electrons, it decomposes into carbon dioxide and water, and the carbon dioxide leaves the reaction system in the form of gas.
[0035] In the second reaction path, elemental iodine meets potassium hydroxide, and the two undergo a disproportionation reaction to produce potassium iodide and potassium iodate. Subsequently, potassium iodate meets potassium formate. Since potassium iodate has strong oxidizing properties and potassium formate has reducing properties, potassium iodate captures electrons from the formate ion, and potassium iodate is reduced to iodide ions by the formate ion to obtain potassium iodide. At the same time, after the formate ion is oxidized and loses electrons, it decomposes into carbon dioxide and water, and the carbon dioxide leaves the reaction system in the form of gas.
[0036] Furthermore, potassium hydroxide reacts quickly with elemental iodine to consume the elemental iodine and prevent the elemental iodine from escaping during the reaction.
[0037] In addition, since the redox reaction system is alkaline, during the redox reaction, although potassium hydroxide reacts with elemental iodine to produce potassium iodate, it is more difficult for iodate ions to react with iodide ions to produce iodine, thus avoiding the occurrence of iodine escape.
[0038] Wherein, in the redox reaction system, the molar ratio of potassium hydroxide to potassium formate may be 0.5 to 1. Exemplarily, the molar ratio of potassium hydroxide to potassium formate may be 0.5, 0.6, 0.7, 0.8, 0.9 or 1. The molar ratio of potassium hydroxide to potassium formate is controlled to be 0.5 to 1, which is conducive to the full reaction of elemental iodine and potassium formate in the redox reaction system, so that iodine is fully reduced by formate ions, thereby improving the recovery rate of iodine element.
[0039] Among them, in the redox reaction system, the molar ratio of iodine element to formate can be 0.9 - 1.1. Exemplarily, the molar ratio of iodine element to formate can be 0.9, 1.0 or 1.1. The molar ratio of iodine element to formate is relatively close, so that iodine is fully reduced to iodide ions, and at the same time, formate reacts fully, reducing the remaining formate from entering the potassium iodide solution and affecting the product quality.
[0040] Among them, the first temperature can be 60°C - 85°C. Exemplarily, the first temperature can be 60°C, 65°C, 70°C, 75°C, 80°C or 85°C. Since the redox reaction system is alkaline, in order to increase the rate of iodine element oxidizing formate ions and the rate of iodate oxidizing formate ions, the first temperature is appropriately increased.
[0041] Among them, after the redox reaction is completed, solid-liquid separation operations such as centrifugation or filtration can be performed on the redox reaction solution to remove insoluble solid impurities in the redox reaction solution, and the redox reaction solution after solid-liquid separation enters the subsequent treatment steps.
[0042] (2) Precipitation reaction step: A precipitant is added to the redox reaction solution, and the precipitation reaction is carried out at the second temperature, and the obtained reaction solution is subjected to solid-liquid separation to obtain a potassium iodide solution.
[0043] Among them, the precipitant can be potassium hydroxide, and soluble impurities in the redox reaction solution react with potassium hydroxide to form a precipitate. Exemplarily, the soluble impurities in the redox reaction solution are metal impurities, and metal ions react with potassium hydroxide to form hydroxide precipitates, so that the soluble impurities in the redox reaction solution are converted into precipitates. Using potassium hydroxide as the precipitant can avoid introducing new impurities into the reaction system.
[0044] Among them, the second temperature is 70 - 90°C, and the pH value of the precipitation reaction is 8 - 10. Specifically, controlling the reaction system of the precipitation reaction to be alkaline and controlling the second temperature within a relatively high range is conducive to the full progress of the precipitation reaction, enabling impurities to precipitate fully, and thus improving the purity of the potassium iodide product.
[0045] Among them, the addition of the precipitant to the redox reaction solution can be achieved by adding a potassium hydroxide solution with a mass percentage of 20% - 50% to the redox reaction solution. By adding the potassium hydroxide solution to the redox reaction solution, compared with directly adding potassium hydroxide solid to the redox reaction solution, it is beneficial for potassium hydroxide to quickly diffuse into the reaction system.
[0046] The solid-liquid separation can be a filtration operation or a centrifugation operation, and the purpose is to remove the precipitate formed by the reaction.
[0047] (3) Evaporation concentration and crystallization steps: Evaporate and concentrate the potassium iodide solution to obtain a concentrated potassium iodide solution, then cool and crystallize the concentrated potassium iodide solution and separate the solid from the liquid to obtain potassium iodide crystals and a potassium iodide mother liquor respectively, and add the potassium iodide mother liquor to the redox reaction system.
[0048] Among them, the potassium iodide solution can be evaporated and concentrated until the solution density of the potassium iodide solution is 1.70 g / cm 3 ~1.90 g / cm 3 ; At this time, part of the solvent in the potassium iodide solution evaporates and leaves the reaction system, and the evaporated solvent can be recycled.
[0049] Among them, the evaporated and concentrated potassium iodide solution is further cooled and crystallized to obtain potassium iodide crystals and a potassium iodide mother liquor; then the potassium iodide crystals are separated from the potassium iodide mother liquor by solid-liquid separation. The solid-liquid separation can be a filtration operation or a centrifugation operation.
[0050] Among them, the potassium iodide crystals can be further centrifuged to remove the moisture in the potassium iodide crystals. Exemplarily, the water content in the potassium iodide crystals can be controlled below 7% (mass percentage).
[0051] Among them, the potassium iodide mother liquor can be added to the redox reaction system in the following manner:
[0052] (1) Mix the crude iodine containing elemental iodine, the potassium iodide mother liquor and a first solvent to obtain an iodine-containing aqueous solution.
[0053] Among them, the first solvent can be water, and the mass percentage of elemental iodine in the crude iodine can be greater than or equal to 90%.
[0054] Among them, the iodine-containing aqueous solution includes 1 part by mass of elemental iodine, 2.5 - 3.5 parts by mass of the potassium iodide mother liquor and 1.5 - 2.5 parts by mass of the first solvent.
[0055] (2) Mix potassium hydroxide, potassium formate and a second solvent to obtain a reducing solution.
[0056] Among them, the second solvent can be water, and the molar ratio of potassium hydroxide to potassium formate in the reducing solution is 0.5 - 1.
[0057] Among them, the mass ratio of potassium hydroxide to water in the reducing solution is 4 - 6. By controlling the mass ratio of potassium hydroxide to water, the mass concentration of potassium hydroxide and the mass concentration of potassium formate in the reducing solution can be controlled to avoid saturation of potassium hydroxide and potassium formate.
[0058] (3) Add the reducing solution to the iodine-containing aqueous solution to obtain a redox reaction system.
[0059] The method for cyclic preparation of potassium iodide according to the embodiment of the present application includes performing a redox reaction in a redox reaction system containing elemental iodine, potassium hydroxide, and potassium formate at a first temperature to obtain a redox reaction solution; adding a precipitant to the redox reaction solution, performing a precipitation reaction at a second temperature, and subjecting the obtained reaction solution to solid-liquid separation to obtain a potassium iodide solution; evaporating and concentrating the potassium iodide solution to obtain a potassium iodide evaporation concentrate, performing cooling crystallization and solid-liquid separation on the potassium iodide evaporation concentrate to obtain potassium iodide crystals and a potassium iodide mother liquor respectively, and adding the potassium iodide mother liquor to the redox reaction system; in the above manner, potassium iodide is formed by a redox method, and potassium iodide can be obtained by performing a single reaction in a reaction system. Subsequently, impurities are removed by using a precipitant. During the entire reaction process, only solid impurities and the solvent evaporated in the evaporation and concentration step leave the reaction system, realizing the recycling of raw materials and being beneficial to improving the utilization rate of raw materials.
[0060] The present application will be further described below through specific examples and comparative examples.
[0061] Example 1:
[0062] Take 352.8 g of crude iodine with an iodine content of 90%, add 500 g of potassium iodide mother liquor and 200 g of water to obtain a first reaction solution. Take 66.15 g of potassium hydroxide with a potassium hydroxide content of 90%; 126.55 g of potassium formate with a potassium formate content of 97%, add 200 g of water to obtain a second reaction solution. Slowly add the first reaction solution to the second reaction solution, keep the temperature of the reaction system at 76 °C, react for 2 h, and filter to obtain a third reaction solution. Add a 25% potassium hydroxide solution to the third reaction solution, adjust the pH of the solution to 9, keep the temperature of the reaction system at 82 °C, react for 3 h, let it stand for 2 h after the reaction, filter to obtain a potassium iodide solution, and control the solution density to 1.80 g / cm 3 , stop concentration, and obtain a potassium iodide product after cooling crystallization. The purity is 99.0%, meeting the chemical pure standard in GB / T 1272-2007, and the iodine yield is 97%.
[0063] Example 2:
[0064] Take 846.67 g of crude iodine with an iodine content of 90%, add 835 g of potassium iodide mother liquor and 700 g of water to obtain the first reaction solution. Take 168.67 g of potassium hydroxide with a potassium hydroxide content of 90%; 318.57 g of potassium formate with a potassium formate content of 98%, add 450 g of water to obtain the second reaction solution. Slowly add the first reaction solution to the second reaction solution, keep the temperature of the reaction system at 76 °C, react for 2 h, and filter to obtain the third reaction solution. Add a 25% potassium hydroxide solution by mass to the third reaction solution, adjust the pH of the solution to 9, keep the temperature of the reaction system at 82 °C, react for 3 h, let it stand for 2 h after the reaction, filter to obtain a potassium iodide solution, and evaporate and concentrate to control the solution density to 1.80 g / cm 3 , stop concentration, cool and crystallize to obtain a potassium iodide product with a purity of 99.2%, meeting the chemical pure standard in GB / T 1272 - 2007, and the iodine yield is 96%.
[0065] Example 3:
[0066] Take 1411.11 g of crude iodine with an iodine content of 90%, add 1169 g of potassium iodide mother liquor and 1000 g of water to obtain the first reaction solution. Take 268.44 g of potassium hydroxide with a potassium hydroxide content of 90%; 510.29 g of potassium formate with a potassium formate content of 98%, add 750 g of water to obtain the second reaction solution. Slowly add the first reaction solution to the second reaction solution, keep the temperature of the reaction system at 76 °C, react for 2 h, and filter to obtain the third reaction solution. Add a 25% potassium hydroxide solution by mass to the third reaction solution, adjust the pH of the solution to 9, keep the temperature of the reaction system at 82 °C, react for 3 h, let it stand for 2 h after the reaction, filter to obtain a potassium iodide solution, and evaporate and concentrate to control the solution density to 1.80 g / cm 3 , stop concentration, cool and crystallize to obtain a potassium iodide product with a purity of 98.8%, meeting the chemical pure standard in GB / T 1272 - 2007, and the iodine yield is 95%.
[0067] Example 4:
[0068] Take 4233.33 g of crude iodine with an iodine content of 90%, add 3340 g of potassium iodide mother liquor and 2000 g of water to obtain the first reaction solution. Take 783.33 g of potassium hydroxide with a potassium hydroxide content of 90%; 1548.76 g of potassium formate with a potassium formate content of 98%, add 1100 g of water to obtain the second reaction solution. Slowly add the first reaction solution to the second reaction solution, keep the temperature of the reaction system at 76 °C, react for 2 h, and filter to obtain the third reaction solution. Add a 25% potassium hydroxide solution by mass to the third reaction solution, adjust the pH of the solution to 9, keep the temperature of the reaction system at 82 °C, react for 3 h, let it stand for 2 h after the reaction, filter to obtain a potassium iodide solution, and evaporate and concentrate to control the solution density to 1.80 g / cm3 Stop concentration, and obtain potassium iodide product after cooling crystallization. The purity is 99.0%, meeting the chemical pure standard in GB / T 1272 - 2007, and the iodine yield is 96%.
[0069] Example 5:
[0070] Take 10160 g of crude iodine with an iodine content of 90%, add 8717 g of potassium iodide mother liquor and 4000 g of water to obtain the first reaction solution. Take 1914 g of potassium hydroxide with a potassium hydroxide content of 90%; 3761 g of potassium formate with a potassium formate content of 98%, add 2500 g of water to obtain the second reaction solution. Slowly add the first reaction solution into the second reaction solution, keep the temperature of the reaction system at 76 °C, react for 2 h, and filter to obtain the third reaction solution. Add a potassium hydroxide solution with a mass ratio of 25% to the third reaction solution, adjust the pH of the solution to 9, keep the temperature of the reaction system at 82 °C, react for 3 h, let it stand for 2 h after the reaction, filter to obtain a potassium iodide solution, and control the solution density to 1.80 g / cm 3 Stop concentration, and obtain potassium iodide product after cooling crystallization. The purity is 98.8%, meeting the chemical pure standard in GB / T 1272 - 2007, and the iodine yield is 95%.
[0071] The technical features of the above embodiments can be combined arbitrarily. For the sake of concise description, not all possible combinations of the technical features in the above embodiments are described. However, as long as there is no contradiction in the combination of these technical features, it should be considered as the scope recorded in this specification.
[0072] The above embodiments only represent the preferred implementation modes of the present application. The description is relatively specific and detailed, but it should not be construed as a limitation to the scope of the patent application. It should be noted that for those of ordinary skill in the art, without departing from the concept of the present application, several modifications and improvements can still be made, and these all belong to the protection scope of the present application. Therefore, the protection scope of the patent of the present application should be subject to the appended claims.
Claims
1. A cyclic preparation method of potassium iodide, characterized in that: include: In a redox reaction system containing elemental iodine, potassium hydroxide and potassium formate, performing a redox reaction at a first temperature to obtain a redox reaction liquid; adding a precipitant to the redox reaction solution, performing a precipitation reaction at a second temperature, and performing solid-liquid separation on the obtained reaction solution to obtain a potassium iodide solution; The potassium iodide solution is evaporated and concentrated to obtain a potassium iodide evaporation concentrate, the potassium iodide evaporation concentrate is cooled and crystallized and solid-liquid separated to obtain potassium iodide crystals and a potassium iodide mother liquor, respectively, and the potassium iodide mother liquor is added to the redox reaction system.
2. The cyclic preparation method of potassium iodide according to claim 1, characterized in that: Adding the potassium iodide mother solution into the redox reaction system comprises: Mixing crude iodine containing elemental iodine, the potassium iodide mother solution and the first solvent to obtain an iodine-containing aqueous solution; Mixing potassium hydroxide, potassium formate and a second solvent to obtain a reducing solution; The reducing solution is added to the iodine-containing aqueous solution to obtain the redox reaction system.
3. The cyclic preparation method of potassium iodide according to claim 2, characterized in that: The iodine-containing aqueous solution includes 1 part by mass of elemental iodine, 2.5 to 3.5 parts by mass of potassium iodide mother solution, and 1.5 to 2.5 parts by mass of a first solvent.
4. The cyclic preparation method of potassium iodide according to claim 1, characterized in that: In the redox reaction system, the molar ratio of the potassium hydroxide to the potassium formate is 0.5-1.
5. The cyclic preparation method of potassium iodide according to claim 4, characterized in that: In the redox reaction system, the molar ratio of iodine element to formate is 0.9 to 1.
1.
6. The cyclic preparation method of potassium iodide according to claim 5, characterized in that: The first temperature is 60°C to 85°C.
7. The cyclic preparation method of potassium iodide according to claim 1, characterized in that: The cyclic preparation method of potassium iodide also includes: The potassium iodide crystals are centrifuged to remove water from the potassium iodide crystals.
8. The cyclic preparation method of potassium iodide according to claim 1, characterized in that: The precipitant is potassium hydroxide, the second temperature is 70-90° C., and the pH value of the precipitation reaction is 8-10.
9. The cyclic preparation method of potassium iodide according to claim 8, characterized in that: The step of adding a precipitant to the redox reaction solution comprises: A potassium hydroxide solution with a mass percentage of 20% to 50% is added to the redox reaction solution.
10. The cyclic preparation method of potassium iodide according to claim 1, characterized in that: The cyclic preparation method of potassium iodide also includes: The redox reaction liquid is subjected to solid-liquid separation to remove solid impurities.