Active iron hydroxide and a method for its production

Abstract

The application discloses active iron hydroxide and a preparation method thereof, and belongs to the technical field of iron hydroxide preparation. The method comprises the following steps: preparing iron nitrate and sodium hydroxide into aqueous solutions respectively; slowly adding the aqueous solution of sodium hydroxide into the aqueous solution of iron nitrate at room temperature until the pH value of the solution reaches 8-10, and then stopping adding the aqueous solution of sodium hydroxide to obtain a mixed solution A; removing impurity ions in the mixed solution A by pure water washing to obtain an aqueous solution of high-purity iron hydroxide; adding p-toluenesulfonic acid into the aqueous solution of iron hydroxide until the pH value of the solution is adjusted to 1-6.8, and then stopping adding the p-toluenesulfonic acid to obtain a mixed solution B; removing iron p-toluenesulfonate in the mixed solution B, and then performing freeze-drying technology treatment to obtain solid active iron hydroxide. The application has the following beneficial effects: the activity of the prepared iron hydroxide can be maintained for a long time, thereby significantly expanding the application range of the iron hydroxide in the market.

Description

Technical Field

[0001] This application relates to the field of ferric hydroxide preparation technology, specifically to an active ferric hydroxide and its preparation method. Background Technology

[0002] Ferrous hydroxide has a wide range of applications, including pharmaceuticals, wastewater treatment, pigment preparation, battery technology, magnetic materials, mining, and water treatment. It is used as a pharmaceutical ingredient, wastewater precipitant, art pigment, battery electrode, and in the preparation of magnetic materials, and also exists in ore form. This versatility allows ferric hydroxide to play an important role in various industries, meeting diverse needs.

[0003] However, ferric hydroxide is one of the less crystallizable species in the iron oxide family, and it can spontaneously transform into the more stable species α-FeOOH and α-Fe2O3, a process known as the aging process of ferric hydroxide. This means that the solubility of ferric hydroxide in acids depends on the preparation time. Freshly prepared ferric hydroxide is readily soluble in inorganic and organic acids, but after a period of time, it transforms into α-FeOOH and α-Fe2O3, making it difficult to dissolve and react further with acids. This property greatly limits the application of ferric hydroxide in actual production. Currently, commercially available solid ferric hydroxide is generally in a deactivated state, making it difficult to react effectively with acids, thus limiting its widespread use in the market. Therefore, it must be prepared and used immediately. Summary of the Invention

[0004] The purpose of this application is to provide an active ferric hydroxide and its preparation method, which can produce a solid ferric hydroxide with high activity over a long period of time, thereby significantly expanding the application scope of ferric hydroxide in the market and solving at least one of the technical problems involved in the background art.

[0005] To solve the above-mentioned technical problems, this application is implemented as follows:

[0006] This application provides a method for preparing active ferric hydroxide, comprising the following steps:

[0007] Step 1: Prepare aqueous solutions of ferric nitrate and sodium hydroxide with concentrations of 15-60% and 5-30%, respectively.

[0008] Step 2: At room temperature, slowly add sodium hydroxide aqueous solution to ferric nitrate aqueous solution until the pH value of the solution reaches 8-10, then stop adding sodium hydroxide aqueous solution to obtain mixed solution A;

[0009] Step 3: Remove impurity ions from mixed solution A by washing with pure water to obtain a high-purity ferric hydroxide aqueous solution;

[0010] Step 4: Add p-toluenesulfonic acid to the ferric hydroxide aqueous solution until the pH value of the solution is adjusted to 1-6.8, then stop adding p-toluenesulfonic acid to obtain mixed solution B;

[0011] Step 5: After removing ferric p-toluenesulfonate from mixed solution B, freeze-drying is performed to obtain solid active ferric hydroxide.

[0012] Furthermore, in step one, ferric nitrate and sodium hydroxide are prepared into aqueous solutions with concentrations of 33% and 16%, respectively.

[0013] Furthermore, in step two, the addition of sodium hydroxide aqueous solution is stopped once the solution pH reaches 9.

[0014] Furthermore, in step three, the pure water washing includes:

[0015] Impurity ions in mixed solution A are removed by washing the precipitate with pure water to remove the supernatant. This washing is repeated multiple times until the conductivity of mixed solution A is below 2 mS / cm. -1 .

[0016] Furthermore, in step three, the impurity ions include nitrate ions and sodium ions.

[0017] Furthermore, in step four, the addition of p-toluenesulfonic acid is stopped after the solution pH is adjusted to 6.

[0018] Furthermore, in step five, ferric p-toluenesulfonate is removed from mixed solution B by washing.

[0019] This application also provides an active ferric hydroxide, prepared by the method described above.

[0020] The beneficial effects of this application are as follows:

[0021] 1. By adding p-toluenesulfonic acid to the ferric hydroxide aqueous solution and adjusting the pH value of the solution to 1-6.8, the activity of ferric hydroxide can be maintained for a long time.

[0022] 2. By using freeze-drying to remove water from the ferric hydroxide solution to obtain solid ferric hydroxide, compared with traditional heating and drying, the ferric hydroxide will not be converted into ferric oxide and thus deactivated, thereby maintaining the activity of the solid ferric hydroxide for a long time. Attached Figure Description

[0023] To more clearly illustrate the technical solutions in the embodiments of the present invention, the accompanying drawings used in the description of the embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort, wherein:

[0024] Figure 1 The image shows the X-ray diffraction (XRD) analysis of the active ferric hydroxide provided in Example 1 of this application. Detailed Implementation

[0025] The technical solutions of the embodiments of this application will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of this application, not all embodiments. Based on the embodiments of this application, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of this application.

[0026] The terms "first," "second," etc., used in the specification and claims of this application are used to distinguish similar objects and not to describe a specific order or sequence. It should be understood that such use of data can be interchanged where appropriate so that embodiments of this application can be implemented in orders other than those illustrated or described herein, and the objects distinguished by "first," "second," etc., are generally of the same class and the number of objects is not limited; for example, a first object can be one or more. Furthermore, in the specification and claims, "and / or" indicates at least one of the connected objects, and the character " / " generally indicates that the preceding and following objects are in an "or" relationship.

[0027] This application provides a method for preparing active ferric hydroxide, comprising the following steps:

[0028] Step 1: Prepare aqueous solutions of ferric nitrate and sodium hydroxide with concentrations of 15-60% and 5-30%, respectively.

[0029] Step 2: At room temperature, slowly add sodium hydroxide aqueous solution to ferric nitrate aqueous solution until the pH value of the solution reaches 8-10, then stop adding sodium hydroxide aqueous solution to obtain mixed solution A;

[0030] Step 3: Remove impurity ions from mixed solution A by washing with pure water to obtain a high-purity ferric hydroxide aqueous solution;

[0031] Step 4: Add p-toluenesulfonic acid to the ferric hydroxide aqueous solution until the pH value of the solution is adjusted to 1-6.8, then stop adding p-toluenesulfonic acid to obtain mixed solution B;

[0032] Step 5: After removing ferric p-toluenesulfonate from mixed solution B, freeze-drying is performed to obtain solid active ferric hydroxide.

[0033] In step one, ferric nitrate and sodium hydroxide are prepared into aqueous solutions with concentrations of 33% and 16%, respectively.

[0034] In step two, stop adding sodium hydroxide solution once the solution pH reaches 9.

[0035] It should be further noted that if the pH value of the solution is lower than 8, it will cause washing difficulties and the activity of ferric hydroxide will be low. Therefore, this application adjusts the pH value of the solution to 8-10, which not only helps to maintain the activity of ferric hydroxide, but also facilitates the washing in subsequent steps.

[0036] Step three involves washing with pure water, including: removing impurity ions from mixed solution A by washing the precipitate with pure water to remove the supernatant; washing multiple times until the conductivity of mixed solution A is below 2 mS / cm. -1 .

[0037] It should be noted that the impurity ions include, but are not limited to, nitrate ions and sodium ions.

[0038] In step four, after adjusting the pH of the solution to 6, stop adding p-toluenesulfonic acid.

[0039] In step five, ferric p-toluenesulfonate is removed from mixed solution B by washing.

[0040] This application also provides an active ferric hydroxide, prepared by the method described above.

[0041] The following detailed description of the active ferric hydroxide and its preparation method provided in this application is based on specific examples 1-7.

[0042] Example 1

[0043] Example 1 provides a method for preparing activated ferric hydroxide, comprising the following steps:

[0044] Step 1: Add 200g of sodium hydroxide to 1000mL of pure water to obtain a 16% sodium hydroxide solution for later use; then add 600g of ferric nitrate nonahydrate to 1200mL of pure water to obtain a 33% ferric nitrate aqueous solution.

[0045] Step 2: Slowly add sodium hydroxide solution to ferric nitrate aqueous solution while stirring rapidly until the pH reaches about 9, then stop adding to obtain an alkaline solution of ferric hydroxide.

[0046] Step 3: Remove impurities such as nitrate and sodium ions from the solution by washing the precipitate with pure water to remove the supernatant. Wash multiple times until the solution conductivity is below 2 mS / cm. -1 This indicates that washing has stopped after the ions in the solution have been largely removed.

[0047] Step 4: After washing, add 30g of p-toluenesulfonic acid to adjust the pH of the solution to about 6;

[0048] Step 5: Remove ferric p-toluenesulfonate from the ferric hydroxide solution by washing, and then remove water from the ferric hydroxide solution by freeze drying to obtain solid activated ferric hydroxide.

[0049] See Figure 1 As shown, X-ray diffraction (XRD) analysis of the obtained solid active ferric hydroxide revealed that ferric hydroxide is amorphous in acidic conditions and crystalline in alkaline conditions. This indicates that the activity of ferric hydroxide can be effectively maintained in acidic conditions, while a ripening process may occur under alkaline conditions.

[0050] Example 2

[0051] Example 2 provides a method for preparing activated ferric hydroxide, comprising the following steps:

[0052] Step 1: Add 200g of sodium hydroxide to 800mL of pure water to obtain a 20% sodium hydroxide solution for later use; then add 600g of ferric nitrate nonahydrate to 1400mL of pure water to obtain a 30% ferric nitrate aqueous solution.

[0053] Step 2: Slowly add sodium hydroxide solution to ferric nitrate aqueous solution while stirring rapidly until the pH reaches about 8.5, then stop adding to obtain an alkaline solution of ferric hydroxide.

[0054] Step 3: Remove impurities such as nitrate and sodium ions from the solution by washing the precipitate with pure water to remove the supernatant. Wash multiple times until the solution conductivity is below 2 mS / cm. -1 This indicates that washing has stopped after the ions in the solution have been largely removed.

[0055] Step 4: After washing, add 28g of p-toluenesulfonic acid to adjust the pH of the solution to about 6;

[0056] Step 5: Remove ferric p-toluenesulfonate from the ferric hydroxide solution by washing, and then remove water from the ferric hydroxide solution by freeze drying to obtain solid activated ferric hydroxide.

[0057] Example 3

[0058] Example 3 provides a method for preparing activated ferric hydroxide, comprising the following steps:

[0059] Step 1: Add 200g of sodium hydroxide to 600mL of pure water to obtain a 25% sodium hydroxide solution for later use; then add 600g of ferric nitrate nonahydrate to 900mL of pure water to obtain a 40% ferric nitrate aqueous solution.

[0060] Step 2: Slowly add sodium hydroxide solution to ferric nitrate aqueous solution while stirring rapidly until the pH reaches about 9.5, then stop adding to obtain an alkaline solution of ferric hydroxide.

[0061] Step 3: Remove impurities such as nitrate and sodium ions from the solution by washing the precipitate with pure water to remove the supernatant. Wash multiple times until the solution conductivity is below 2 mS / cm. -1 This indicates that washing has stopped after the ions in the solution have been largely removed.

[0062] Step 4: After washing, add 35g of p-toluenesulfonic acid to adjust the pH of the solution to about 5.

[0063] Step 5: Remove ferric p-toluenesulfonate from the ferric hydroxide solution by washing, and then remove water from the ferric hydroxide solution by freeze drying to obtain solid activated ferric hydroxide.

[0064] Example 4

[0065] Example 4 provides a method for preparing activated ferric hydroxide, comprising the following steps:

[0066] Step 1: Add 200g of sodium hydroxide to 466mL of pure water to obtain a 30% sodium hydroxide solution for later use; then add 600g of ferric nitrate nonahydrate to 2400mL of pure water to obtain a 20% ferric nitrate aqueous solution.

[0067] Step 2: Slowly add sodium hydroxide solution to ferric nitrate aqueous solution while stirring rapidly until the pH reaches about 9, then stop adding to obtain an alkaline solution of ferric hydroxide.

[0068] Step 3: Remove impurities such as nitrate and sodium ions from the solution by washing the precipitate with pure water to remove the supernatant. Wash multiple times until the solution conductivity is below 2 mS / cm. -1 This indicates that washing has stopped after the ions in the solution have been largely removed.

[0069] Step 4: After washing, add 40g of p-toluenesulfonic acid to adjust the pH of the solution to about 4;

[0070] Step 5: Remove ferric p-toluenesulfonate from the ferric hydroxide solution by washing, and then remove water from the ferric hydroxide solution by freeze drying to obtain solid activated ferric hydroxide.

[0071] Example 5

[0072] Example 5 provides a method for preparing activated ferric hydroxide, comprising the following steps:

[0073] Step 1: Add 200g of sodium hydroxide to 670mL of pure water to obtain a 23% sodium hydroxide solution for later use; then add 600g of ferric nitrate nonahydrate to 1622mL of pure water to obtain a 27% ferric nitrate aqueous solution.

[0074] Step 2: Slowly add sodium hydroxide solution to ferric nitrate aqueous solution while stirring rapidly until the pH reaches about 8.3, then stop adding to obtain an alkaline solution of ferric hydroxide.

[0075] Step 3: Remove impurities such as nitrate and sodium ions from the solution by washing the precipitate with pure water to remove the supernatant. Wash multiple times until the solution conductivity is below 2 mS / cm. -1 This indicates that washing has stopped after the ions in the solution have been largely removed.

[0076] Step 4: After washing, add 42g of p-toluenesulfonic acid to adjust the pH of the solution to about 3;

[0077] Step 5: Remove ferric p-toluenesulfonate from the ferric hydroxide solution by washing, and then remove water from the ferric hydroxide solution by freeze drying to obtain solid activated ferric hydroxide.

[0078] Example 6

[0079] Example 6 provides a method for preparing activated ferric hydroxide, comprising the following steps:

[0080] Step 1: Add 200g of sodium hydroxide to 3800mL of pure water to obtain a 5% sodium hydroxide solution for later use; then add 600g of ferric nitrate nonahydrate to 900mL of pure water to obtain a 40% ferric nitrate aqueous solution.

[0081] Step 2: Slowly add sodium hydroxide solution to ferric nitrate aqueous solution while stirring rapidly until the pH reaches about 8.7, then stop adding to obtain an alkaline solution of ferric hydroxide.

[0082] Step 3: Remove impurities such as nitrate and sodium ions from the solution by washing the precipitate with pure water to remove the supernatant. Wash multiple times until the solution conductivity is below 2 mS / cm. -1 This indicates that washing has stopped after the ions in the solution have been largely removed.

[0083] Step 4: After washing, add 52g of p-toluenesulfonic acid to adjust the pH of the solution to about 2;

[0084] Step 5: Remove ferric p-toluenesulfonate from the ferric hydroxide solution by washing, and then remove water from the ferric hydroxide solution by freeze drying to obtain solid activated ferric hydroxide.

[0085] Example 7

[0086] Example 7 provides a method for preparing activated ferric hydroxide, comprising the following steps:

[0087] Step 1: Add 200g of sodium hydroxide to 1133mL of pure water to obtain a 15% sodium hydroxide solution for later use; then add 600g of ferric nitrate nonahydrate to 400mL of pure water to obtain a 60% ferric nitrate aqueous solution.

[0088] Step 2: Slowly add sodium hydroxide solution to ferric nitrate aqueous solution while stirring rapidly until the pH reaches about 8, then stop adding to obtain an alkaline solution of ferric hydroxide.

[0089] Step 3: Remove impurities such as nitrate and sodium ions from the solution by washing the precipitate with pure water to remove the supernatant. Wash multiple times until the solution conductivity is below 2 mS / cm. -1 This indicates that washing has stopped after the ions in the solution have been largely removed.

[0090] Step 4: After washing, add 53g of p-toluenesulfonic acid to adjust the pH of the solution to an acidic level of about 1.7.

[0091] Step 5: Remove ferric p-toluenesulfonate from the ferric hydroxide solution by washing, and then remove water from the ferric hydroxide solution by freeze drying to obtain solid activated ferric hydroxide.

[0092] The beneficial effects of this application are as follows:

[0093] 1. By adding p-toluenesulfonic acid to the ferric hydroxide aqueous solution and adjusting the pH value of the solution to 1-6.8, the activity of ferric hydroxide can be maintained for a long time.

[0094] 2. By using freeze-drying to remove water from the ferric hydroxide solution to obtain solid ferric hydroxide, compared with traditional heating and drying, the ferric hydroxide will not be converted into ferric oxide and thus deactivated, thereby maintaining the activity of the solid ferric hydroxide for a long time.

[0095] It should be noted that, in this document, the terms "comprising," "including," or any other variations thereof are intended to cover non-exclusive inclusion, such that a process, method, article, or apparatus that comprises a list of elements includes not only those elements but also other elements not expressly listed, or elements inherent to such a process, method, article, or apparatus. Unless otherwise specified, an element defined by the phrase "comprising one..." does not exclude the presence of other identical elements in the process, method, article, or apparatus that includes that element.

[0096] Furthermore, it should be noted that the scope of the methods and systems in the embodiments of this application is not limited to performing functions in the order shown or discussed, but may also include performing functions in a substantially simultaneous manner or in the reverse order, depending on the functions involved. For example, the described methods may be performed in a different order than described, and various steps may be added, omitted, or combined. In addition, features described with reference to certain examples may be combined in other examples.

[0097] The embodiments of this application have been described above with reference to the accompanying drawings. However, this application is not limited to the specific embodiments described above. The specific embodiments described above are merely illustrative and not restrictive. Those skilled in the art can make many other forms under the guidance of this application without departing from the spirit and scope of the claims, and all of these forms are within the protection scope of this application.

Claims

1. A process for the preparation of activated iron hydroxide, characterized in that, The method comprises the following steps: Step one, prepare 15-60% and 5-30% aqueous solution of ferric nitrate and sodium hydroxide respectively; Step two, slowly drop the aqueous solution of sodium hydroxide into the aqueous solution of ferric nitrate at room temperature until the pH value of the solution reaches 8-10, then stop adding the aqueous solution of sodium hydroxide to obtain a mixed solution A; Step three, remove the impurity ions in the mixed solution A by pure water washing to obtain a high-purity aqueous solution of iron hydroxide; Step four, add p-toluenesulfonic acid to the aqueous solution of iron hydroxide until the pH value of the solution is adjusted to 1-6.8, then stop adding the p-toluenesulfonic acid to obtain a mixed solution B; Step five, remove the ferric p-toluenesulfonate in the mixed solution B, and then perform freeze-drying technology treatment to obtain active iron hydroxide in solid form.

2. The active iron oxide hydroxide according to claim 1, characterized in that, In step one, prepare 33% and 16% aqueous solution of ferric nitrate and sodium hydroxide respectively.

3. The activated iron hydroxide according to claim 1, characterized in that, In step two, stop adding the aqueous solution of sodium hydroxide when the pH value of the solution reaches 9.

4. The activated iron hydroxide according to claim 1, characterized in that, In step three, the pure water washing comprises: The impurity ions in the mixed solution A were removed by washing the precipitate with pure water to remove the supernatant, and the washing was repeated until the conductivity of the mixed solution A was less than 2 ms.cm -1 .

5. The active iron hydroxide according to claim 1 or 4, characterized in that, In step three, the impurity ions include nitrate and sodium ions.

6. The activated iron hydroxide according to claim 1, characterized in that, In step four, stop adding the p-toluenesulfonic acid when the pH value of the solution is adjusted to 6.

7. The activated iron hydroxide according to claim 1, characterized in that, In step five, remove the ferric p-toluenesulfonate in the mixed solution B by washing.

8. An activated iron hydroxide, characterized in that, Prepared by the method of any one of claims 1-7.

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