A basic bismuth carbonate and a method for its preparation

Abstract

This application relates to the field of inorganic chemical synthesis technology, specifically disclosing a basic bismuth carbonate and its preparation method. The preparation method involves adding a sodium carbonate solution to a bismuth nitrate solution to prepare a mixed solution; subsequently, adjusting the pH value of the mixed solution and subjecting it to reflux heating to obtain high-purity basic bismuth carbonate. Specifically, this application uses bismuth nitrate solution and sodium carbonate solution as basic reaction raw materials. By precisely controlling key process parameters such as the pH value of the reaction system, the heating reflux time, and the temperature, the microstructure of the product is controlled to achieve efficient separation of impurities. Only a conventional water washing purification process is needed to effectively remove soluble impurities from the system, ultimately obtaining high-purity basic bismuth carbonate. This solves the technical problems of existing synthesis processes, such as insufficient purity, complex processes, low safety, and difficulty in adapting to industrial mass production requirements.

Description

Technical Field

[0001] This application relates to the field of inorganic chemical synthesis technology, and in particular to a basic bismuth carbonate and its preparation method. Background Technology

[0002] Basic bismuth carbonate, as an inorganic chemical raw material, can be used in catalytic systems, cobalt salt preparation, ceramic coloring, electronic and magnetic material additives, and other fields. It is also a raw material for veterinary antidiarrheal drugs, used to treat gastrointestinal inflammation and diarrhea in animals.

[0003] Existing processes for preparing basic bismuth carbonate primarily rely on chemical precipitation, which generally suffers from low product purity and lengthy process flows. To prepare high-purity basic bismuth carbonate, Chinese patent CN103359789B uses bismuth nitrate and sodium carbonate as reaction substrates, and introduces a modified polyacrylamide-co-styrene-co-acrylic acid copolymer to adsorb and remove heavy metal impurities from the raw materials, yielding pharmacopoeia-grade basic bismuth carbonate. Chinese patent CN103253705A uses refined bismuth to react with ammonium bicarbonate to synthesize high-purity basic bismuth carbonate. However, both of these synthetic routes suffer from problems such as vigorous reactions, easy release of ammonia gas, and poor production safety, posing potential health hazards to operators. Furthermore, subsequent impurity removal steps rely on polymer adsorbent processes, making the operation complex and industrial implementation difficult.

[0004] In summary, the industry urgently needs to develop a new process for preparing basic bismuth carbonate that is easy to operate, has stable reaction, good safety, and produces high-purity products, in order to overcome the many shortcomings of existing technologies. Summary of the Invention

[0005] In view of this, the purpose of this application is to provide a basic bismuth carbonate and its preparation method to solve the technical problems of existing synthesis processes such as substandard purity, complex process flow, low safety, and difficulty in adapting to the needs of industrial mass production.

[0006] To achieve the above-mentioned technical objectives, this application provides a method for preparing high-purity basic bismuth carbonate, comprising the following steps:

[0007] Step S1: Mix sodium carbonate solution and bismuth nitrate solution evenly to obtain a mixed solution, and maintain the temperature of the mixed solution at 40-50℃ during the mixing process;

[0008] Step S2: Adjust the pH of the mixed solution to 9-10, heat the mixed solution to 95-100℃, and keep it under reflux for 10-30 minutes to obtain crude basic bismuth carbonate product.

[0009] Step S3: Wash and dry the crude basic bismuth carbonate product to obtain basic bismuth carbonate.

[0010] Furthermore, in the bismuth nitrate solution, the concentration of Bi is 1.58–2.37 mol / L, and the concentration of free acid is 0.78–1.57 mol / L; the concentration of sodium carbonate solution is 2.83–3.77 mol / L.

[0011] Furthermore, the molar ratio of sodium carbonate to bismuth nitrate is 2.4–2.8:1.

[0012] Furthermore, in step S2, the pH value is adjusted using a dilute nitric acid solution with a concentration of 10–25 wt%.

[0013] Furthermore, the method for preparing bismuth nitrate solution is as follows: concentrated nitric acid and purified water are mixed evenly to obtain an acidic solution; bismuth oxide is added to the acidic solution and stirred evenly to obtain bismuth nitrate solution;

[0014] During the addition of bismuth oxide, the temperature of the mixture formed by the acidic solution and bismuth oxide is kept below 60°C.

[0015] Furthermore, the volume ratio of concentrated nitric acid to purified water is 1-2:1-2; the mass-volume ratio of bismuth oxide to acidic solution is 1:2-3.

[0016] Furthermore, the washing process involves pulping and washing.

[0017] Furthermore, during pulping and washing, the solid-liquid volume ratio is 1:3 to 5; and the number of washing cycles is 3 to 4.

[0018] Further, the drying process involves drying at 90–100°C for 20–25 hours.

[0019] This application provides a basic bismuth carbonate, which is prepared using a method for preparing basic bismuth carbonate.

[0020] In summary, this application provides a method for preparing high-purity basic bismuth carbonate. The method involves adding a sodium carbonate solution to a bismuth nitrate solution to prepare a mixed solution; subsequently, adjusting the pH of the mixed solution and subjecting it to reflux heating to obtain high-purity basic bismuth carbonate. This application uses bismuth nitrate solution and sodium carbonate solution as basic reaction raw materials. By precisely controlling key process parameters such as the pH value of the reaction system, the reflux time, and the temperature, the microstructure of the product is controlled to achieve efficient separation of impurities. Only a conventional water washing purification process is needed to effectively remove soluble impurities from the system. No additional adsorbents are required for deep impurity removal throughout the process, ultimately yielding high-purity basic bismuth carbonate that meets pharmacopoeia standards.

[0021] Compared to existing technologies, this application eliminates the use of ammonium bicarbonate as a raw material, thereby eliminating the risk of ammonia release and the potential for violent reactions at the source, significantly improving the safety and stability of the production process. Furthermore, the subsequent impurity removal process eliminates the need for polymer adsorbents and associated post-treatment steps, simplifying the process and reducing production costs. Therefore, the preparation method provided in this application is controllable, highly adaptable to equipment, and directly suitable for continuous industrial production, demonstrating promising prospects for industrial application. Attached Figure Description

[0022] To more clearly illustrate the technical solutions in the embodiments of this application or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of this application. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0023] Figure 1 This is a process flow diagram for the preparation of basic bismuth carbonate provided in Example 1 of this application;

[0024] Figure 2 This is a 30Kx SEM image of basic bismuth carbonate provided in Example 1 of this application;

[0025] Figure 3 The image shows the XRD pattern of basic bismuth carbonate provided in Example 1 of this application. Detailed Implementation

[0026] 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, not all, of the embodiments of this application. Based on the embodiments in this application specification, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection claimed in this application.

[0027] In the description of this application, it should be noted that the terms "center," "upper," "lower," "left," "right," "vertical," "horizontal," "inner," and "outer," indicating orientation or positional relationships, are only for the convenience of describing this application and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation, and therefore should not be construed as a limitation on this application. Furthermore, the terms "first," "second," and "third" are used for descriptive purposes only and should not be construed as indicating or implying relative importance.

[0028] Unless otherwise explicitly specified and limited, the terms "installation," "connection," and "linking" should be interpreted broadly. For example, they can refer to fixed connections, detachable connections, or integral connections; they can refer to mechanical connections or electrical connections; they can refer to direct connections or indirect connections through an intermediate medium; and they can refer to the internal connection between two components. Those skilled in the art can understand the specific meaning of the above terms in this application based on the specific circumstances. Furthermore, there are no particular restrictions on the source of all raw materials used in this invention; they can be purchased commercially or prepared using conventional methods well known to those skilled in the art.

[0029] This application provides a method for preparing high-purity basic bismuth carbonate, comprising the following steps:

[0030] Step S1: Mix sodium carbonate solution and bismuth nitrate solution evenly to obtain a mixed solution, and maintain the temperature of the mixed solution at 40-50℃ during the mixing process;

[0031] Step S2: Adjust the pH of the mixed solution to 9-10, heat the mixed solution to 95-100℃, and keep it under reflux for 10-30 minutes to obtain crude basic bismuth carbonate product.

[0032] Step S3: Wash and dry the crude basic bismuth carbonate product to obtain basic bismuth carbonate.

[0033] It should be noted that after adjusting the pH of the mixed solution to the preset range, the reaction system must be heated to 90-100℃ and kept at that temperature for 10-30 minutes. If the reaction temperature or time is lower than this process range, the bismuth content of the final basic bismuth carbonate will not meet the standard.

[0034] In some embodiments, the concentration of Bi in the bismuth nitrate solution is 1.58–2.37 mol / L, the concentration of free acid is 0.78–1.57 mol / L, and the concentration of sodium carbonate solution is 2.83–3.77 mol / L.

[0035] In some preferred embodiments, the molar ratio of sodium carbonate to bismuth nitrate is 2.4 to 2.8:1.

[0036] It should be noted that when the molar ratio of sodium carbonate to bismuth nitrate is less than 2.4, the amount of sodium carbonate added will be insufficient, which will result in the acid-generating capacity of the obtained basic bismuth carbonate being unqualified.

[0037] In some embodiments, in step S2, a dilute nitric acid solution with a concentration of 10–25 wt% is used to adjust the pH value.

[0038] In some embodiments, concentrated nitric acid is mixed with purified water to obtain an acidic solution; bismuth oxide is added to the acidic solution and stirred until homogeneous to obtain a bismuth nitrate solution; during the addition of bismuth oxide, the temperature of the mixture formed by the acidic solution and bismuth oxide is kept below 60°C.

[0039] In some embodiments, the volume ratio of concentrated nitric acid to purified water is 1-2:1-2; the mass-volume ratio of bismuth oxide to acidic solution is 1:2-3.

[0040] It should be noted that the unit of mass-volume ratio can be g / mL or kg / L, that is, the mass-volume ratio of bismuth oxide and acidic solution is 1g:(2~3)mL or 1kg:(2~3)L.

[0041] In some specific embodiments, the volume ratio of concentrated nitric acid to purified water is 1:1; the mass-volume ratio of bismuth oxide to acidic solution is 1:2.

[0042] In some embodiments, washing is pulping washing.

[0043] In some preferred embodiments, the solid-liquid volume ratio during pulping and washing is 1:3 to 5; and the number of washing cycles is 3 to 4.

[0044] In some embodiments, the drying process is performed by drying at a temperature of 90–100°C for 20–25 hours.

[0045] This application provides a basic bismuth carbonate, which is prepared using a method for preparing basic bismuth carbonate.

[0046] The applicant further provides the following specific embodiments to describe the present invention. It should be noted that these embodiments are merely descriptive and do not limit the present invention in any way.

[0047] Example 1

[0048] See Figure 1 This embodiment provides a method for preparing basic bismuth carbonate, including the following steps:

[0049] Step S1: Prepare bismuth nitrate solution and sodium carbonate solution respectively;

[0050] Preparation of bismuth nitrate solution: 465 mL of purified water and 465 mL of 65% concentrated nitric acid were added sequentially to a reaction vessel equipped with a stirring and temperature control device. Stirring was started until the purified water and nitric acid were fully mixed. Bismuth oxide was added in batches, with the addition rate dynamically adjusted according to the real-time temperature of the reaction system to ensure the temperature of the entire reaction system remained below 60°C. After all 465 g of bismuth oxide had been added, the reaction was stirred for 3 hours to obtain a bismuth nitrate solution, which was then allowed to stand for later use. In this embodiment, the molar concentration of bismuth ions in the bismuth nitrate solution was stable at 1.58–2.37 mol / L, the molar concentration of free acid was controlled at 0.78–1.57 mol / L, and the contents of various metal impurities and anionic impurities all met the company's internal quality control standards.

[0051] Preparation of sodium carbonate solution: Place 1.4L of purified water in a reaction vessel, add 510g of anhydrous sodium carbonate, start stirring and heat the reaction system to 40℃, stir at a constant temperature until the sodium carbonate powder is completely dissolved, and obtain a clear and homogeneous sodium carbonate aqueous solution for later use.

[0052] Step S2: Prepare crude basic bismuth carbonate;

[0053] Sodium carbonate solution was added to bismuth nitrate solution at a uniform rate over a period of 25 minutes, maintaining the system temperature at 40°C throughout the addition process. Once all sodium carbonate solution had been added, a mixed solution was obtained. The pH of the mixed solution was adjusted to 9.2 using a 25% (w / w) dilute nitric acid solution. The solution was then heated to 95°C and refluxed for 20 minutes to obtain a solid-liquid mixture. The solid-liquid mixture was centrifuged to separate the solid, which was identified as crude basic bismuth carbonate.

[0054] Step S3, post-processing of crude basic bismuth carbonate product;

[0055] The crude basic bismuth carbonate product was subjected to multiple pulping and washing processes, with each pulping and stirring lasting 20 minutes. The system temperature was maintained at 30–40°C throughout the washing process to obtain wet basic bismuth carbonate. The wet basic bismuth carbonate was then dried at 95°C for 20 hours to obtain dried basic bismuth carbonate. The basic bismuth carbonate was then mechanically pulverized to reduce the particle size to below 200 mesh to facilitate subsequent physicochemical testing.

[0056] Figure 2 The image shows the SEM morphology of the basic bismuth carbonate prepared in this embodiment at 30,000x magnification. As can be seen from the image, the prepared basic bismuth carbonate has a plate-like microstructure with particle size distribution ranging from 100 to 500 nm.

[0057] Figure 3The XRD pattern of the basic bismuth carbonate prepared in this embodiment is shown. The diffraction peaks of the pattern are compared with the standard PDF card of basic bismuth carbonate. The positions and relative intensities of each characteristic diffraction peak correspond one-to-one, confirming that the target compound basic bismuth carbonate can be stably synthesized in this embodiment.

[0058] Example 2

[0059] This embodiment provides a method for preparing basic bismuth carbonate, including the following steps:

[0060] Step S1: Prepare bismuth nitrate solution and sodium carbonate solution respectively;

[0061] Preparation of bismuth nitrate solution: Add 410 mL of purified water and 410 mL of 65% concentrated nitric acid sequentially to a reaction vessel equipped with a stirring and temperature control device. Stir until the purified water and nitric acid are fully mixed. Add bismuth oxide in batches, dynamically adjusting the addition rate based on the real-time temperature of the reaction system throughout the process to ensure the temperature of the entire reaction system remains below 60°C. After all 410 g of bismuth oxide has been added, stir the reaction for 3 hours to obtain a bismuth nitrate solution, which is then set aside for later use. In this embodiment, the molar concentration of bismuth ions in the bismuth nitrate solution is stable at 1.58–2.37 mol / L, the molar concentration of free acid is controlled at 0.78–1.57 mol / L, and the contents of various metal impurities and anionic impurities all meet the company's internal quality control standards.

[0062] Preparation of sodium carbonate solution: Place 1.4L of purified water in a reaction vessel, add 510g of anhydrous sodium carbonate, start stirring and heat the reaction system to 40℃, stir at a constant temperature until the sodium carbonate powder is completely dissolved, and obtain a clear and homogeneous sodium carbonate aqueous solution for later use.

[0063] Step S2: Prepare crude basic bismuth carbonate;

[0064] Sodium carbonate solution was added to bismuth nitrate solution at a uniform rate over a period of 30 minutes, maintaining the system temperature at 40°C throughout the addition process. Once all sodium carbonate solution had been added, a mixed solution was obtained. The pH of the mixed solution was adjusted to 9.1 using a 20% (w / w) dilute nitric acid solution. The mixed solution was then heated to 100°C and refluxed for 17 minutes to obtain a solid-liquid mixture. The solid-liquid mixture was then centrifuged to separate the solid, which was identified as crude basic bismuth carbonate.

[0065] Step S3, post-processing of crude product;

[0066] The crude basic bismuth carbonate product was subjected to multiple pulping and washing processes, with each pulping and stirring lasting 20 minutes. The system temperature was maintained at 30–40°C throughout the washing process to obtain wet basic bismuth carbonate. The wet basic bismuth carbonate was then dried at 90°C for 22 hours to obtain dried basic bismuth carbonate. The basic bismuth carbonate was then mechanically pulverized to reduce the particle size of the pulverized powder to less than 200 mesh.

[0067] Example 3

[0068] This embodiment provides a method for preparing basic bismuth carbonate, including the following steps:

[0069] Step S1: Prepare bismuth nitrate solution and sodium carbonate solution respectively;

[0070] Preparation of bismuth nitrate solution: Add 500 mL of purified water and 500 mL of 65% concentrated nitric acid sequentially to a reaction vessel equipped with a stirring and temperature control device. Stir until the purified water and nitric acid are fully mixed. Add bismuth oxide in batches, dynamically adjusting the addition rate based on the real-time temperature of the reaction system throughout the process to ensure the temperature of the entire reaction system remains below 60°C. After all 500 g of bismuth oxide has been added, stir the reaction for 3 hours to obtain a bismuth nitrate solution, which is then set aside for later use. In this embodiment, the molar concentration of bismuth ions in the bismuth nitrate solution is stable at 1.58–2.37 mol / L, the molar concentration of free acid is controlled at 0.78–1.57 mol / L, and the contents of various metal impurities and anionic impurities all meet the company's internal quality control standards.

[0071] Preparation of sodium carbonate solution: Place 1.5L of purified water in a reaction vessel, add 590g of anhydrous sodium carbonate, start stirring and heat the reaction system to 43℃, stir at a constant temperature until the sodium carbonate powder is completely dissolved, and obtain a clear and homogeneous sodium carbonate aqueous solution for later use.

[0072] Step S2: Prepare crude basic bismuth carbonate;

[0073] Sodium carbonate solution was added to bismuth nitrate solution at a uniform rate over a period of 27 minutes, maintaining the system temperature at 43°C throughout the addition process. Once all sodium carbonate solution had been added, a mixed solution was obtained. The pH of the mixed solution was adjusted to 9.3 using a 20% (w / w) dilute nitric acid solution. The mixed solution was then heated to 100°C and refluxed for 17 minutes to obtain a solid-liquid mixture. The solid-liquid mixture was then centrifuged to separate the solid, which was identified as crude basic bismuth carbonate.

[0074] Step S3, post-processing of crude product;

[0075] The crude basic bismuth carbonate product was subjected to multiple pulping and washing processes, with each pulping and stirring lasting 20 minutes. The system temperature was maintained at 30–40°C throughout the washing process to obtain wet basic bismuth carbonate. The wet basic bismuth carbonate was then dried at 90°C for 20 hours to obtain dried basic bismuth carbonate. The basic bismuth carbonate was then mechanically pulverized to reduce the particle size of the pulverized powder to less than 200 mesh.

[0076] According to the testing methods specified in the pharmacopoeias of various countries, the basic bismuth carbonate prepared in Examples 1 to 3 were tested for physicochemical properties. The test items and results are detailed in Table 1 below.

[0077] Table 1. Detection Items and Results of Basic Bismuth Carbonate

[0078]

[0079] Note: For the test items in Table 1, the test methods recorded in the Pharmacopoeia of the People's Republic of China shall be used first. If the Pharmacopoeia of the People's Republic of China does not record the corresponding test method for the test item, the test methods recorded in the United States Pharmacopeia or the European Pharmacopoeia shall be used.

[0080] As shown in Table 1, the basic bismuth carbonate prepared in the examples meets all the quality standards of the Chinese Pharmacopoeia, the United States Pharmacopoeia, and the European Pharmacopoeia for all key parameters such as physicochemical properties, impurity limits, content, and particle size. The product purity and pharmaceutical performance meet the requirements and can satisfy the requirements for use as a pharmaceutical raw material.

[0081] The above are merely preferred embodiments of this application and are not intended to limit the present invention. Although this application has been described in detail with reference to the embodiments, those skilled in the art can still modify the technical solutions described in the foregoing embodiments or make equivalent substitutions for some of the technical features. However, any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of this application should be included within the protection scope of this application.

Claims

1. A method for preparing basic bismuth carbonate, characterized in that, Includes the following steps: Step S1: Mix sodium carbonate solution and bismuth nitrate solution evenly to obtain a mixed solution, and maintain the temperature of the mixed solution at 40-50℃ during the mixing process; Step S2: Adjust the pH of the mixed solution to 9-10, heat the mixed solution to 95-100°C, and reflux for 10-30 minutes to obtain crude basic bismuth carbonate product; Step S3: The crude basic bismuth carbonate product is washed and dried to obtain basic bismuth carbonate.

2. The preparation method according to claim 1, characterized in that, In the bismuth nitrate solution, the concentration of Bi is 1.58–2.37 mol / L and the concentration of free acid is 0.78–1.57 mol / L; the concentration of the sodium carbonate solution is 2.83–3.77 mol / L.

3. The preparation method according to claim 1 or 2, characterized in that, The molar ratio of sodium carbonate to bismuth nitrate is 2.4 to 2.8:

1.

4. The preparation method according to claim 1, characterized in that, In step S2, a dilute nitric acid solution with a concentration of 10-25 wt% is used to adjust the pH value.

5. The preparation method according to claim 1, characterized in that, The method for preparing the bismuth nitrate solution is as follows: concentrated nitric acid and purified water are mixed evenly to obtain an acidic solution; bismuth oxide is added to the acidic solution and stirred evenly to obtain the bismuth nitrate solution. During the addition of bismuth oxide, the temperature of the mixture formed by the acidic solution and the bismuth oxide is kept below 60°C.

6. The preparation method according to claim 5, characterized in that, The volume ratio of concentrated nitric acid to purified water is 1-2:1-2; the mass-volume ratio of bismuth oxide to the acidic solution is 1:2-3.

7. The preparation method according to claim 1, characterized in that, The washing process is pulping and washing.

8. The preparation method according to claim 7, characterized in that, In the pulping and washing process, the solid-liquid volume ratio is 1:3 to 5, and the washing is performed 3 to 4 times.

9. The preparation method according to claim 1, characterized in that, The drying process is as follows: drying at 90-100℃ for 20-25 hours.

10. A basic bismuth carbonate, characterized in that, It is prepared by the preparation method according to any one of claims 1 to 9.

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