A method for preparing sodium periodate

Abstract

The application discloses a preparation method of sodium periodate. The method comprises the following steps: dissolving sodium iodate in deionized water, adding an acidic reagent to adjust the pH value of the solution to 1-3, then adding a transition metal salt catalyst, and then adding sodium persulfate in batches; after the feeding is completed, the system is heated to 50-60 DEG C for a heat preservation reaction; after the reaction is completed, sodium periodate is obtained through post-treatment. Under the acidic condition, the catalyst is used to activate sodium persulfate to generate strong oxidizing sulfate radicals, the radicals can efficiently oxidize IO3 ‑ of sodium iodate into IO4 ‑ , directly generate sodium periodate, and no intermediate preparation step is needed, so that the process steps are simple, the reaction efficiency is improved, the production cycle is shortened, the oxidation efficiency and utilization rate of sodium persulfate are improved, the problem of excessive oxidation to generate impurities in the ozone oxidation method is avoided, the product yield is greater than or equal to 92%, and the purity is greater than or equal to 99.0%.

Description

Technical Field

[0001] This invention belongs to the field of inorganic oxidant preparation technology, specifically relating to a method for preparing sodium periodate. Background Technology

[0002] Sodium periodate (NaIO4) is an important inorganic oxidant that is widely used in the pharmaceutical industry, food processing, chromatographic analysis, organic synthesis and other fields, playing a key role as a pharmaceutical intermediate, oxidant and analytical reagent.

[0003] Existing methods for preparing sodium periodate mainly include chlorine oxidation, sodium persulfate oxidation under alkaline conditions, electrolysis, and ozone oxidation. Each method has significant technical drawbacks.

[0004] Chlorine oxidation method: Iodine is mixed with sodium hydroxide solution, and chlorine gas is introduced to react and generate trisodium dihydrogen periodate intermediate, which is then converted into sodium periodate by nitric acid acidification. However, this method has problems such as high raw material consumption, large amount of sodium hydroxide, generation of a large amount of waste liquid containing sodium chloride, and serious environmental pollution. In addition, chlorine is a toxic and irritating gas, and the safety requirements for storage and use are extremely high, making operation and control difficult.

[0005] The sodium persulfate oxidation method under alkaline conditions (such as the technology disclosed in CN102583252B) requires adding sodium iodate and sodium persulfate to a sodium hydroxide solution and reacting at 80–90°C to generate trisodium dihydrogen periodate precipitate, which is then dehydrated by nitric acid to convert it into sodium periodate. Although this method avoids the use of chlorine gas, it still requires a step-by-step process, first preparing an intermediate and then converting it into the target product, making the process cumbersome. Furthermore, the oxidation efficiency of sodium persulfate is limited in the alkaline reaction system, requiring high-temperature reaction to ensure conversion, resulting in high energy consumption.

[0006] Electrolysis: By electrolyzing an aqueous solution of sodium iodate, IO3 is generated at the anode (commonly made of lead dioxide, platinum, etc.). ⁻ The oxidation reaction produces IO4 ⁻ Sodium periodate is prepared by this method. This method does not require the addition of an oxidant and is theoretically more environmentally friendly, but it has significant limitations: First, the investment cost of the electrolytic cell is high, the electrode material requirements are stringent (it needs to be resistant to strong oxidation and acid corrosion), and the electrodes are prone to passivation and deactivation, resulting in high maintenance costs; second, the reaction rate is slow, and the unit production capacity is low, making it difficult to meet the needs of large-scale industrial production; third, the electrolysis process requires precise control of parameters such as current density and cell voltage, making operation difficult and prone to product decomposition or impurity generation due to excessive local reactions.

[0007] Ozone oxidation method: This method utilizes the strong oxidizing properties of ozone to oxidize sodium iodate to sodium periodate in an aqueous solution. The core problem with this method is the low utilization rate of ozone; most of the ozone decomposes and dissipates without participating in the reaction, leading to high raw material consumption and high production costs. Furthermore, ozone is a strong oxidizing gas, requiring extremely high equipment sealing; leaks pose a safety risk. In addition, ozone easily converts some IO3 during the reaction. ⁻ Excessive oxidation results in other iodine oxide impurities, affecting product purity and making subsequent separation and purification more difficult.

[0008] Therefore, developing a simple, mild, environmentally friendly, efficient, and cost-controllable method for preparing sodium periodate has become an urgent technical problem to be solved in this field. Summary of the Invention

[0009] The technical problem to be solved by the present invention is to provide a method for preparing sodium periodate. The method has simple steps, mild reaction conditions, fast reaction rate, high oxidation efficiency and utilization rate of oxidant, low production cost, and the generated waste liquid is easy to treat and environmentally friendly.

[0010] To address the above technical problems, this invention discloses a method for preparing sodium periodate, comprising the following steps: dissolving sodium iodate in deionized water, adjusting the pH of the solution to 1-3 with an acidic reagent, adding a catalyst, and then adding sodium persulfate in batches; after the addition is complete, heating the system to 50-60°C and maintaining the temperature for the reaction; after the reaction is complete, obtaining sodium periodate through post-treatment; the catalyst is a transition metal salt. The catalyst is used to activate the decomposition of sodium persulfate to produce highly oxidizing SO4. - Free radicals that can efficiently remove IO3 from sodium iodate. - Oxidized to IO4 - This increases the reaction rate.

[0011] The pH of the solution was adjusted to 1–3 using an acidic reagent. This range ensures that sodium persulfate decomposes to produce sufficient SO4. - Free radicals, and can also avoid IO3 - A disproportionation reaction occurs, ensuring reaction selectivity.

[0012] The reaction formula for preparing sodium periodate in this invention is as follows:

[0013]

[0014] Furthermore, the mass ratio of deionized water to sodium iodate is 5 to 20:1. Preferably, it is 5:1.

[0015] Furthermore, the acidic reagent is nitric acid or sulfuric acid.

[0016] Furthermore, the transition metal salt is one or more of silver, copper, manganese, iron, cobalt, nickel, palladium, ruthenium, or platinum.

[0017] Furthermore, the anions of the silver salt, copper salt, manganese salt, iron salt, cobalt salt, nickel salt, palladium salt, ruthenium salt, or platinum salt are each independently selected from sulfate, nitrate, or chloride ions.

[0018] Furthermore, the mass of the catalyst is 1 / 100 to 1 / 10000 of the mass of sodium iodate.

[0019] Furthermore, the molar ratio of sodium persulfate to sodium iodate is 1.0–2.0:1.0. This molar ratio ensures that sodium iodate is fully oxidized while avoiding excessive sodium persulfate residue, thus reducing the burden on subsequent separation and improving the utilization rate of the oxidant.

[0020] Furthermore, the method of adding sodium persulfate in batches is to divide the sodium persulfate into three equal parts and add them in three separate batches, with a 10-minute interval between each two consecutive additions.

[0021] Furthermore, the heat preservation reaction is considered complete when the starch-potassium iodide test paper does not turn blue. The heat preservation reaction time is generally ≥2.5 hours. When the heat preservation reaction time reaches 2.5 hours, a sample is taken and tested with starch-potassium iodide test paper. If the starch-potassium iodide test paper does not turn blue, the reaction ends; if the starch-potassium iodide test paper turns blue, the reaction continues until the starch-potassium iodide test paper does not turn blue.

[0022] Furthermore, the post-processing includes the following steps performed in sequence: vacuum concentration, low-temperature crystallization, filtration, washing (using cold water at 0–5°C), and drying. The vacuum concentration and low-temperature crystallization are used to further improve the yield and purity of the product.

[0023] The beneficial effects of this invention are:

[0024] 1. This invention utilizes a catalyst to activate the decomposition of sodium persulfate under acidic conditions (pH=1-3) to generate highly oxidizing sulfate radicals. These radicals can efficiently decompose IO3 in sodium iodate. - Oxidized to IO4 - This process directly generates sodium periodate without intermediate preparation steps, simplifying the process and improving not only the reaction rate and production cycle but also the oxidation efficiency and utilization of sodium persulfate. Simultaneously, it avoids the problem of over-oxidation and impurities associated with ozone oxidation, resulting in a product yield ≥92% and purity ≥99.0%, meeting the requirements for pharmaceutical and electronic applications.

[0025] 2. Compared with the sodium persulfate oxidation method under alkaline conditions (reaction temperature of 80-90℃), the reaction temperature of this invention is 50-60℃. The whole process does not require harsh conditions such as high pressure and strong electrolysis, has lower energy consumption, and is safer and more controllable in operation.

[0026] 3. This invention requires only about 1 mol of sodium periodate, 1 mol of sodium iodate, and 1 mol of sodium persulfate and water to produce 1 mol of sodium periodate, resulting in low raw material consumption. Furthermore, the entire reaction process produces no toxic gases, and the waste liquid mainly contains easily treatable salts such as sodium bisulfate, minimizing environmental impact. Simultaneously, the entire process does not require complex electrolysis equipment or precise parameter control, leading to lower production costs and enabling large-scale production through scale-up reaction equipment. Detailed Implementation

[0027] The present invention will be further explained below with reference to the embodiments. The following embodiments are for illustrative purposes only and are not intended to limit the scope of the invention.

[0028] Example 1

[0029] (1) Dissolve 59.4 g (0.3 mol) sodium iodate in 300 mL of deionized water. Adjust the pH of the solution to 1.0 with 65% nitric acid. Add 1.0 g of silver nitrate as a catalyst. Then, divide 76 g (0.32 mol) sodium persulfate into three equal portions and add them in three separate additions, with a 10-minute interval between each addition. After the addition is complete, heat the system to 60 °C and stir for 2.5 h. Take a sample and test it with starch-potassium iodide paper. The reaction is complete when the paper does not turn blue.

[0030] (2) After the reaction was completed, 100g of distilled water was distilled off under reduced pressure at a vacuum of -0.095MPa and a temperature of 50℃. The concentrate was then cooled to 0℃ and crystallized at a constant temperature for 1h. After crystallization, the product was filtered, collected, washed with 20mL of cold water at 5℃, and dried at a temperature of 65℃ and a vacuum of -0.095MPa for 4.5h to obtain 59.7g of sodium periodate product, with a yield of 92.7% and a purity of 99.7%.

[0031] Example 2

[0032] (1) Dissolve 59.4 g (0.3 mol) sodium iodate in 300 mL of deionized water. Adjust the pH of the solution to 1.5 with 98% sulfuric acid. Add a mixture of 0.8 g silver nitrate and 0.8 g copper sulfate as a catalyst. Divide 76 g (0.32 mol) sodium persulfate into three equal portions and add them in three separate additions, with a 10-minute interval between each addition. After the addition is complete, heat the system to 60 °C and stir for 2.5 h. Take a sample and test it with starch-potassium iodide paper. The reaction is complete when the paper does not turn blue.

[0033] (2) After the reaction was completed, 100g of distilled water was distilled off under reduced pressure at a vacuum of -0.095MPa and a temperature of 50℃. The concentrated solution was then cooled to 0℃ and crystallized at a constant temperature for 1h. After crystallization, the solution was filtered, the crystallized product was collected, washed with 20mL of cold water at 5℃, and dried at a temperature of 65℃ and a vacuum of -0.095MPa for 4.5h to obtain 60.5g of sodium periodate product, with a yield of 94.1% and a purity of 99.8%.

[0034] Example 3

[0035] (1) Dissolve 59.4 g (0.3 mol) sodium iodate in 300 mL of deionized water. Adjust the pH of the solution to 2.5 with 65% nitric acid. Add a mixture of 0.8 g silver nitrate and 0.8 g manganese nitrate as a catalyst. Divide 76 g (0.32 mol) sodium persulfate into three equal portions and add them in three separate additions, with a 10-minute interval between each addition. After the addition is complete, heat the system to 60 °C and stir for 2.5 h. Take a sample and test it with starch-potassium iodide paper. The reaction is complete when the paper does not turn blue.

[0036] (2) After the reaction was completed, 100g of distilled water was distilled off under reduced pressure at a vacuum of -0.095MPa and a temperature of 50℃. The concentrate was then cooled to 0℃ and crystallized at a constant temperature for 1h. After crystallization, the product was filtered, collected, washed with 20mL of cold water at 5℃, and dried at a temperature of 65℃ and a vacuum of -0.095MPa for 4.5h to obtain 60.2g of sodium periodate product, with a yield of 93.4% and a purity of 99.6%.

[0037] Of course, the present invention may have other various embodiments. Without departing from the spirit and essence of the present invention, those skilled in the art can make various corresponding changes and modifications according to the present invention, but these corresponding changes and modifications should all fall within the protection scope of the claims of the present invention.

Claims

1. A method for preparing sodium periodate, characterized in that, Includes the following steps: Sodium iodate was dissolved in deionized water, and the pH of the solution was adjusted to 1-3 by adding an acidic reagent. Then, a catalyst was added, followed by sodium persulfate in batches. After the addition was completed, the system was heated to 50-60°C and the reaction was carried out under heat preservation. After the reaction was completed, sodium periodate was obtained through post-treatment. The catalyst was a transition metal salt.

2. The preparation method according to claim 1, characterized in that, The mass ratio of deionized water to sodium iodate is 5–20:

1.

3. The preparation method according to claim 1, characterized in that, The acidic reagent is nitric acid or sulfuric acid.

4. The preparation method according to claim 1, characterized in that, The transition metal salt is one or more of the following: silver salt, copper salt, manganese salt, iron salt, cobalt salt, nickel salt, palladium salt, ruthenium salt, or platinum salt.

5. The preparation method according to claim 4, characterized in that, The anions of the silver salt, copper salt, manganese salt, iron salt, cobalt salt, nickel salt, palladium salt, ruthenium salt, or platinum salt are each independently selected from sulfate, nitrate, or chloride ions.

6. The preparation method according to claim 1, characterized in that, The mass of the catalyst is 1 / 100 to 1 / 10000 of the mass of sodium iodate.

7. The preparation method according to claim 1, characterized in that, The molar ratio of sodium persulfate to sodium iodate is 1.0–2.0:1.

0.

8. The preparation method according to claim 1 or 7, characterized in that, The method for adding sodium persulfate in batches is to divide the sodium persulfate into three equal parts and add them in three separate batches, with a 10-minute interval between each two consecutive additions.

9. The preparation method according to claim 1, characterized in that, The heat preservation reaction was defined as ending when the starch-potassium iodide test paper did not turn blue.

10. The preparation method according to claim 1, characterized in that, The post-processing includes, in sequence, vacuum concentration, low-temperature crystallization, filtration, washing, and drying.