Preparation method of potassium iodide
By adding a mixed solution of potassium hydroxide and potassium formate to the iodine solution for reaction, the elemental iodine is reduced to iodine ions under alkaline conditions, which solves the problem of iodine running in the preparation of potassium iodide, improves the purity of potassium iodide, and simplifies the process flow.
Patent Information
- Application Number
- CN202510393950.3
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2025-03-31
- Publication Date
- 2025-06-17
AI Technical Summary
In the prior art, there is iodine elimination phenomenon during the preparation of potassium iodide, which leads to waste of raw materials and reduced KI purity, making it difficult to improve the purity of potassium iodide.
Add a mixed solution of potassium hydroxide and potassium formate to the iodine solution for the first reaction. The elemental iodine is reduced to iodine ions under alkaline conditions, reducing the difficulty of reacting IO3- and I- in an acidic environment to generate I2, thereby reducing the occurrence of iodine-running phenomenon.
Through this method, the purity of potassium iodide is improved, the occurrence of iodine-free phenomenon is reduced, the process flow is simple and the operation is convenient.
Smart Images
Figure CN120157159A_ABST
Abstract
Description
Technical Field
[0001] This application relates to the technical field of potassium iodide preparation, and particularly to a method for preparing potassium iodide. Background Art
[0002] Iodine is one of the essential trace elements for life. It participates in the synthesis of thyroid hormones and is directly related to brain tissue and body development. A lack of iodine in the body can cause a series of metabolic disorders, resulting in goiter, cretinism, etc.
[0003] 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. Utilizing its antifungal activity, it can be clinically used to treat sporotrichosis, chromoblastomycosis, persistent nodular erythema, nodular vasculitis, etc. In the chemical industry, 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 poorly soluble metal iodides, and can also be used for chromatographic analysis and spot pain analysis. It can be used to prepare an iodine-potassium iodide-water etching solution for wet etching of chips.
[0004] Potassium iodide has a wide range of uses, but due to its photosensitivity and hygroscopicity, its preparation is relatively difficult, which limits its production and application. Currently, the commonly used method for preparing potassium iodide is the formic acid reduction method. Iodine undergoes a disproportionation reaction under alkaline conditions to form KI and KIO3, and KIO3 is reduced to KI under the action of HCOOH. During the preparation process, IO3 - and I - are prone to react in an acidic environment to form I2, causing iodine leakage, resulting in waste of raw materials and a decrease in the purity of KI. Summary of the Invention
[0005] Based on this, this application provides a method for preparing potassium iodide to solve the technical problem in the prior art that is not conducive to improving the purity of potassium iodide.
[0006] An embodiment of this application provides a method for preparing potassium iodide, including:
[0007] Adding a reducing solution to an iodine solution for a first reaction to obtain a first reaction solution, wherein the reducing solution includes potassium hydroxide and potassium formate;
[0008] Performing solid-liquid separation on the first reaction solution to obtain a first reaction filtrate, and adding a potassium hydroxide solution to the first reaction filtrate for a second reaction to obtain a second reaction solution;
[0009] Performing solid-liquid separation on the second reaction solution to obtain a potassium iodide solution.
[0010] Optionally, the mass ratio of crude iodine to the first solvent in the iodine solution is 2 to 3.
[0011] Optionally, the molar ratio of potassium hydroxide to potassium formate in the reduction solution is 0.5 to 1.
[0012] Optionally, the mass ratio of potassium hydroxide to the second solvent in the reduction solution is 4 to 6.
[0013] Optionally, the reaction temperature of the first reaction is 40°C to 85°C.
[0014] Optionally, the reaction temperature of the first reaction is 60°C to 85°C.
[0015] Optionally, the molar ratio of iodine element to formate in the reaction system of the first reaction is 0.9 to 1.3.
[0016] Optionally, the pH of the second reaction is 7.5 to 11.5, and the reaction temperature of the second reaction is 70°C to 95°C.
[0017] Optionally, the preparation method of potassium iodide further includes:
[0018] Evaporating and concentrating the potassium iodide solution until the solution density of the potassium iodide solution is 1.70 g / cm 3 ~1.90 g / cm 3 ;
[0019] Cooling and crystallizing the evaporated and concentrated potassium iodide solution to obtain potassium iodide products.
[0020] Optionally, the reaction time of the first reaction is 2 hours, and the reaction time of the second reaction is 3 hours.
[0021] The preparation method of potassium iodide provided by the embodiment of the present application is as follows: First, add a reduction solution to an iodine solution for a first reaction to obtain a first reaction solution, wherein the reduction solution includes potassium hydroxide and potassium formate; then, perform solid-liquid separation on the first reaction solution to obtain a first reaction filtrate, and add a potassium hydroxide solution to the first reaction filtrate for a second reaction to obtain a second reaction solution; finally, perform solid-liquid separation on the second reaction solution to obtain a potassium iodide solution; by adding a mixed solution of potassium hydroxide and potassium formate to the iodine solution for the first reaction, and using formate to reduce elemental iodine to iodide ions under alkaline conditions, the difficulty of the reaction between iodate ions and iodide ions to generate elemental iodine is increased, which is beneficial to reducing the iodine leakage phenomenon and improving the purity of potassium iodide; at the same time, the process flow is simple and the operation is convenient. BRIEF DESCRIPTION OF THE DRAWINGS
[0022] Figure 1 It is a process flow diagram of the preparation method of potassium iodide according to an embodiment of the present application.
[0023] Figure 2Schematic flow diagram of another embodiment of the preparation method of potassium iodide according to an embodiment of the present application. Detailed implementation manners
[0024] The following details the implementation manners of the present application. Examples of the implementation manners are shown in the accompanying drawings, where the same or similar reference numerals denote the same or similar elements or elements with the same or similar functions throughout. The implementation manners described below with reference to the accompanying drawings are exemplary only for explaining the present application and should not be construed as limiting the present application.
[0025] In order to enable those skilled in the art of the present technology to better understand the solutions of the present application, the technical solutions in the embodiments of the present application will be clearly and completely described below in conjunction with the accompanying drawings in the embodiments of the present application. Obviously, the described embodiments are only a part of the embodiments of the present application, rather than all the embodiments. Based on the embodiments of the present application, all other embodiments obtained by those skilled in the art without creative efforts fall within the scope of protection of the present application.
[0026] In the embodiments of the present application, it should be noted that in this text, relational terms such as first and second are only used to distinguish one entity or operation from another entity or operation, and do not necessarily require or imply any actual relationship or order between these entities or operations.
[0027] Moreover, the term "comprising", "including" or any other variant thereof is intended to cover non-exclusive inclusion, such that a process, method, article or device comprising a series of elements includes not only those elements but also other elements not expressly listed, or elements inherent to such process, method, article or device. Without further limitation, an element defined by the statement "comprising one..." does not exclude the presence of additional identical elements in the process, method, article or device comprising the element.
[0028] In the description of the embodiments of the present application, words such as "example" or "for example" are used to represent examples, explanations or descriptions. Any embodiment or design solution described as "for example" or "for instance" in the embodiments of the present application is not construed as being more preferred or having more advantages than another embodiment or design solution. The use of words such as "example" or "for example" is intended to present relative concepts in a clear manner.
[0029] In addition, the "plurality" in the embodiments of the present application refers to two or more than two. In view of this, in the embodiments of the present application, "plurality" can also be understood as "at least two". "At least one" can be understood as one or more, for example, one, two or more. For example, including at least one means including one, two or more, and there is no limit on which ones are included. For example, including at least one of A, B and C, then A, B, C, A and B, A and C, B and C, or A, B and C can be included.
[0030] It should be noted that, in the embodiments of the present application, "and / or" describes the association relationship of the associated objects, indicating that three relationships may exist. For example, A and / or B may represent: A exists alone, A and B exist at the same time, and B exists alone. In addition, the character " / ", unless otherwise specified, generally indicates that the associated objects before and after are in an "or" relationship.
[0031] like Figures 1 to 2 As shown, it is a method for preparing potassium iodide according to an embodiment of the present application.
[0032] like Figure 1 As shown, the method for preparing potassium iodide comprises the steps of:
[0033] Step S11: adding a reducing solution to the iodine solution to perform a first reaction to obtain a first reaction solution, wherein the reducing solution includes potassium hydroxide and potassium formate.
[0034] The iodine solution may be prepared by mixing elemental iodine with a first solvent, or the iodine solution may be prepared by mixing crude iodine with a first solvent, wherein the iodine solution contains elemental iodine, and illustratively, the first solvent may be water.
[0035] The reducing solution may be prepared by mixing potassium hydroxide, potassium formate and a second solvent. For example, the second solvent may be water.
[0036] The reducing solution can be slowly added to the iodine solution to cause a first reaction. The reducing solution is a mixed solution of potassium hydroxide and potassium formate, the reducing solution is alkaline, and the reaction system of the first reaction formed after the reducing solution and the iodine solution are mixed is alkaline. The elemental iodine in the reaction system has strong oxidizing properties. When the elemental iodine encounters formate, it takes away electrons from the formate and is reduced to iodide ions by the formate; the formate loses electrons and is oxidized and decomposed into carbon dioxide and water, and the obtained first reaction solution contains potassium iodide.
[0037] Specifically, first, elemental iodine meets potassium hydroxide, and the two undergo a disproportionation reaction to generate potassium iodide and potassium iodate. Potassium hydroxide reacts quickly with elemental iodine, consuming elemental iodine and preventing elemental iodine from escaping during the reaction.
[0038] Subsequently, potassium iodate meets potassium formate. Since potassium iodate is highly oxidizing and potassium formate is reducing, potassium iodate takes electrons from formate and is reduced to iodide ions by formate to obtain potassium iodide. At the same time, after the formate 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.
[0039] At the same time, when elemental iodine meets potassium formate, due to its strong oxidizing property, it will seize electrons from the formate ion, and the elemental iodine 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.
[0040] Since the reaction system of the first reaction is alkaline, during the first reaction, although potassium hydroxide reacts with elemental iodine to form potassium iodate, it is more difficult for iodate ions to react with iodide ions to form iodine, which greatly reduces the probability of iodine escape.
[0041] Step S12: performing solid-liquid separation on the first reaction liquid to obtain a first reaction filtrate, adding potassium hydroxide solution to the first reaction filtrate to perform a second reaction to obtain a second reaction liquid.
[0042] The first reaction liquid is subjected to solid-liquid separation to remove insoluble impurities in the first reaction liquid. For example, the solid-liquid separation can be performed by centrifugation, and the first reaction liquid is centrifuged to obtain a precipitate and a supernatant, wherein the precipitate is the insoluble impurities in the first reaction liquid, and the supernatant is the first reaction filtrate.
[0043] The second reaction is a precipitation reaction, wherein the first reaction filtrate contains potassium iodide and soluble impurities, and potassium hydroxide solution is added to react the soluble impurities with potassium hydroxide to form a precipitate. For example, when crude iodine is used to prepare an iodine solution, the crude iodine contains metal impurities, and the metal ions react with potassium hydroxide to form a hydroxide precipitate, so that the soluble impurities are converted into a precipitate.
[0044] The second reaction liquid contains potassium iodide and precipitate generated by the reaction of soluble impurities with potassium hydroxide.
[0045] Step S13: performing solid-liquid separation on the second reaction liquid to obtain a potassium iodide solution.
[0046] The second reaction liquid is subjected to solid-liquid separation to remove the precipitate formed by soluble impurities in the second reaction liquid. For example, the solid-liquid separation can be performed by centrifugation, and the second reaction liquid is centrifuged to obtain a precipitate and a supernatant, wherein the precipitate is the precipitate formed by the soluble impurities, and the supernatant is the potassium iodide solution.
[0047] In this embodiment, a first reaction is carried out by adding a mixed solution of potassium hydroxide and potassium formate to an iodine solution. Under alkaline conditions, formate ions are used to reduce elemental iodine to iodide ions, which increases the difficulty of the reaction between iodate ions and iodide ions to form elemental iodine, is beneficial to reducing iodine leakage, and is beneficial to improving the purity of potassium iodide. At the same time, the process flow is simple and the operation is convenient.
[0048] As an implementation manner, the iodine solution can be prepared by mixing crude iodine with a first solvent. The mass ratio of crude iodine to the first solvent in the iodine solution is 2 - 3, and the mass percentage of iodine in the crude iodine is greater than or equal to 90%. When the mass ratio of crude iodine to the first solvent is 2 - 3, the phenomenon of iodine element dissipation is reduced.
[0049] In this implementation manner, configuring the mass ratio of iodine to water in the iodine solution within the above range is beneficial to reducing the phenomenon of iodine element dissipation and improving the recovery rate of iodine element.
[0050] As an implementation manner, the molar ratio of potassium hydroxide to potassium formate in the reduction solution is 0.5 - 1.
[0051] Thus, in the reaction system of the first reaction, the molar ratio of potassium hydroxide to potassium formate is 0.5 - 1, which is beneficial to the full reaction of elemental iodine with potassium formate, enables iodine to be fully reduced by formate ions, and further improves the recovery rate of iodine element.
[0052] As an implementation manner, the mass ratio of potassium hydroxide to a second solvent in the reduction solution is 4 - 6.
[0053] By controlling the mass ratio of potassium hydroxide to the second solvent, the mass concentration of potassium hydroxide and the mass concentration of potassium formate in the reduction solution can be controlled to avoid saturation of the reduction solution.
[0054] As an implementation manner, the reaction temperature of the first reaction is 40°C - 85°C. The reduction solution is slowly added to the iodine solution to obtain the reaction system of the first reaction, and the temperature of this reaction system is controlled at 40°C - 85°C to carry out the first reaction.
[0055] In this implementation manner, controlling the reaction temperature of the first reaction within the above range is beneficial to the full progress of the reaction, enables iodine to be fully reduced by formate ions, and further improves the recovery rate of iodine element.
[0056] In some implementation manners, since the reaction system of the first reaction is alkaline, in order to increase the oxidation rate of formate ions by elemental iodine, the reaction temperature of the first reaction is controlled at 60°C - 85°C.
[0057] As an implementation manner, the molar ratio of iodine element to formate in the reaction system of the first reaction is 0.9 - 1.3.
[0058] In this embodiment, by controlling the molar ratio of iodine to formate to 0.9 - 1.3, iodine is fully reduced to iodide ions, and at the same time, formate reacts sufficiently, reducing the remaining formate from entering the potassium iodide solution and affecting the product quality.
[0059] In some embodiments, the molar ratio of iodine element to formate in the reaction system of the first reaction is 0.95 - 1.05.
[0060] In some embodiments, the molar ratio of iodine element to formate in the reaction system of the first reaction is 1:1.
[0061] As one embodiment, the pH of the second reaction is 7.5 - 11.5, and the reaction temperature of the second reaction is 70°C - 95°C.
[0062] In this embodiment, controlling the reaction system of the second reaction to be alkaline and simultaneously controlling the reaction temperature of the second reaction within the above range is conducive to the full progress of the second reaction, enabling impurities to precipitate sufficiently, and thereby improving the purity of the potassium iodide product.
[0063] As one embodiment, the method for preparing potassium iodide in this example further includes the following steps after the steps:
[0064] Step S14: Evaporate and concentrate the potassium iodide solution until the solution density of the potassium iodide solution is 1.70 g / cm 3 ~1.90 g / cm 3 ;
[0065] Step S15: Cool and crystallize the evaporated and concentrated potassium iodide solution to obtain a potassium iodide product.
[0066] In this embodiment, through evaporation concentration and cooling crystallization, potassium iodide crystals are formed from iodide ions and potassium ions in the solution to make full use of the iodine element in the crude iodine.
[0067] In this embodiment, the utilization rate of the iodine element in the crude iodine is achieved to be greater than or equal to 95%, and the obtained potassium iodide meets the chemical pure standard in GB / T 1272 - 2007.
[0068] In some embodiments, in step S15, the potassium iodide product can be further centrifuged to control the water content rate of the potassium iodide product to be lower than 7%.
[0069] As one embodiment, the reaction time of the first reaction is 2 hours, and the reaction time of the second reaction is 3 hours.
[0070] In some embodiments, the method of solid-liquid separation can be centrifugation or filtration.
[0071] In this embodiment, the process for preparing potassium iodide products from crude iodine is simple in process, simple in raw materials, high in economic value, has no special requirements for crude iodine, and has strong adaptability to raw materials.
[0072] The following further illustrates the present application through specific examples and comparative examples.
[0073] Example 1:
[0074] Take 70.5 g of crude iodine with an iodine content of 90%, add 211.5 g of water to obtain an iodine solution. Take 13.3 g of potassium hydroxide with a potassium hydroxide content of 90%; 28.9 g of potassium formate with a potassium formate content of 98%, add 66.5 g of water to obtain a reduction solution. Slowly add the reduction solution to the iodine solution, keep the temperature of the reaction system at 76 °C, react for 2 h, and filter to obtain the first reaction solution. Add a 25% potassium hydroxide solution by mass to the first 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 5 h after the reaction, filter to obtain a potassium iodide solution, evaporate and concentrate to control the solution density to 1.80 g / cm3, stop concentration, and obtain potassium iodide products after cooling crystallization, with a purity of 99.0%, meeting the chemical pure standard in GB / T 1272-2007, and an iodine yield of 98%.
[0075] Example 2:
[0076] Take 70.5 g of crude iodine with an iodine content of 90%, add 211.5 g of water to obtain an iodine solution. Take 12.4 g of potassium hydroxide with a potassium hydroxide content of 90%; 28.9 g of potassium formate with a potassium formate content of 98%, add 62.0 g of water to obtain a reduction solution. Slowly add the reduction solution to the iodine solution, keep the temperature of the reaction system at 76 °C, react for 2 h, and filter to obtain the first reaction solution. Add a 25% potassium hydroxide solution by mass to the first 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 5 h after the reaction, filter to obtain a potassium iodide solution, evaporate and concentrate to control the solution density to 1.80 g / cm3, stop concentration, and obtain potassium iodide products after cooling crystallization, with a purity of 99.2%, meeting the chemical pure standard in GB / T 1272-2007, and an iodine yield of 96%.
[0077] Example 3:
[0078] Take 70.5 g of crude iodine with an iodine content of 90%, add 211.5 g of water to obtain an iodine solution. Take 14.2 g of potassium hydroxide with a potassium hydroxide content of 90%; 28.9 g of potassium formate with a potassium formate content of 98%, add 71.0 g of water to obtain a reduction solution. Slowly add the reduction solution to the iodine solution, keep the temperature of the reaction system at 76 °C, react for 2 h, and filter to obtain the first reaction solution. Add a 25% potassium hydroxide solution by mass to the first 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 5 h after the reaction, filter to obtain a potassium iodide solution, evaporate and concentrate to control the solution density to 1.80 g / cm3, stop concentration, and obtain a potassium iodide product after cooling crystallization, with a purity of 98.8%, meeting the chemical pure standard in GB / T 1272 - 2007, and the iodine yield is 95%.
[0079] Example 4:
[0080] Take 70.5 g of crude iodine with an iodine content of 90%, add 211.5 g of water to obtain an iodine solution. Take 13.3 g of potassium hydroxide with a potassium hydroxide content of 90%; 24.6 g of potassium formate with a potassium formate content of 98%, add 66.5 g of water to obtain a reduction solution. Slowly add the reduction solution to the iodine solution, keep the temperature of the reaction system at 76 °C, react for 2 h, and filter to obtain the first reaction solution. Add a 25% potassium hydroxide solution by mass to the first 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 5 h after the reaction, filter to obtain a potassium iodide solution, evaporate and concentrate to control the solution density to 1.80 g / cm3, stop concentration, and obtain a potassium iodide product after cooling crystallization, with a purity of 99.2%, meeting the chemical pure standard in GB / T 1272 - 2007, and the iodine yield is 96%.
[0081] Example 5:
[0082] Take 70.5 g of crude iodine with an iodine content of 90%, add 211.5 g of water to obtain an iodine solution. Take 13.3 g of potassium hydroxide with a potassium hydroxide content of 90%; 25.7 g of potassium formate with a potassium formate content of 98%, add 66.5 g of water to obtain a reduction solution. Slowly add the reduction solution to the iodine solution, keep the temperature of the reaction system at 76 °C, react for 2 h, and filter to obtain the first reaction solution. Add a 25% potassium hydroxide solution by mass to the first 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 5 h after the reaction, filter to obtain a potassium iodide solution, evaporate and concentrate to control the solution density to 1.80 g / cm3, stop concentration, and obtain a potassium iodide product after cooling crystallization, with a purity of 99.3%, meeting the chemical pure standard in GB / T 1272 - 2007, and the iodine yield is 97%.
[0083] The technical features of the above embodiments can be combined arbitrarily. For the sake of brevity of 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.
[0084] The above embodiments only express the preferred embodiments of the present application, and the description is relatively specific and detailed. However, it should not be construed as a limitation on 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 shall be subject to the appended claims.
Claims
1. A method for preparing potassium iodide, characterized in that: include: Adding a reducing solution to the iodine solution for a first reaction to obtain a first reaction solution, wherein the reducing solution comprises potassium hydroxide and potassium formate; Performing solid-liquid separation on the first reaction liquid to obtain a first reaction filtrate, and adding a potassium hydroxide solution to the first reaction filtrate to perform a second reaction to obtain a second reaction liquid; The second reaction liquid is subjected to solid-liquid separation to obtain a potassium iodide solution.
2. The method for preparing potassium iodide according to claim 1, wherein The mass ratio of crude iodine to the first solvent in the iodine solution is 2-3.
3. The method for preparing potassium iodide according to claim 1, characterized in that The molar ratio of the potassium hydroxide to the potassium formate in the reducing solution is 0.5-1.
4. The method for preparing potassium iodide according to claim 3, characterized in that The mass ratio of the potassium hydroxide to the second solvent in the reducing solution is 4-6.
5. The method for preparing potassium iodide according to claim 3, characterized in that The reaction temperature of the first reaction is 40°C to 85°C.
6. The method for preparing potassium iodide according to claim 5, characterized in that: The reaction temperature of the first reaction is 60°C to 85°C.
7. The method for preparing potassium iodide according to claim 1, characterized in that The molar ratio of iodine element to formate in the reaction system of the first reaction is 0.9 to 1.
3.
8. The method for preparing potassium iodide according to claim 1, characterized in that The pH of the second reaction is 7.5-11.5, and the reaction temperature of the second reaction is 70°C-95°C.
9. The method for preparing potassium iodide according to claim 1, characterized in that The preparation method of potassium iodide also includes: The potassium iodide solution is evaporated and concentrated until the solution density of the potassium iodide solution is 1.70 g / cm 3 ~1.90g / cm 3 ; The potassium iodide solution after evaporation and concentration is cooled and crystallized to obtain a potassium iodide product.
10. The method for preparing potassium iodide according to claim 1, characterized in that: The reaction time of the first reaction is 2 hours, and the reaction time of the second reaction is 3 hours.