Preparation process of food-grade high-purity sodium pyrophosphate
By optimizing the preparation process parameters and steps, the problems of insufficient purity and residual impurities in sodium pyrophosphate were solved, and the preparation of high-purity sodium pyrophosphate was achieved, meeting the high-quality requirements of the food industry.
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- GUIZHOU KAIYANG PHOSPHORUS CHEM CO LTD
- Filing Date
- 2026-02-10
- Publication Date
- 2026-05-15
AI Technical Summary
The existing sodium pyrophosphate preparation process results in low product purity, a large amount of harmful impurities, and insufficient precision in process parameter control, making it difficult to meet the food industry's demand for high purity and high safety.
By optimizing raw material pretreatment, controlling dissolution temperature and pH value, neutralization reaction conditions, polymerization dehydration pressure, and activated carbon decolorization, combined with vacuum drying and ultrafine grinding, a complete preparation process is formed, including raw material screening and pretreatment, batching and dissolution, neutralization reaction, polymerization dehydration, purification and refining, and drying and grinding steps, ensuring the accuracy of process parameters and the effective removal of impurities.
The efficient preparation and deep purification of sodium pyrophosphate have been achieved, with a product purity of over 96.5% and a significant reduction in impurity content, meeting the food industry's requirements for high purity and high safety.
Smart Images
Figure CN122035807A_ABST
Abstract
Description
Technical Field
[0001] This invention relates to the field of yellow phosphorus chemical technology, and in particular to a preparation process for food-grade high-purity sodium pyrophosphate. Background Technology
[0002] Sodium pyrophosphate is a widely used additive in the food industry, which improves food stability, taste, and extends shelf life. With the development of the food industry, the demand for high-purity, high-quality sodium pyrophosphate is increasing, and its market size continues to expand, showing promising application prospects.
[0003] Currently, most common processes for preparing sodium pyrophosphate use sodium dihydrogen phosphate as a raw material, which is obtained through neutralization, polymerization, and dehydration. However, existing processes still have shortcomings in terms of raw material pretreatment, reaction control, and impurity removal. For example, the product purity is not high, there are relatively high levels of harmful impurities such as heavy metals, and the process parameters are not precisely controlled. These factors restrict the development of sodium pyrophosphate towards higher quality and safety in the food industry.
[0004] Therefore, in order to improve the product quality of sodium pyrophosphate and meet the requirements of the food industry for high-purity and safe additives, it is necessary to improve the existing preparation process and develop a preparation method that can achieve efficient purification, strict impurity control, and is suitable for the production of food-grade high-purity sodium pyrophosphate. Summary of the Invention
[0005] The purpose of this invention is to provide a preparation process for food-grade high-purity sodium pyrophosphate, which solves the problems of insufficient product purity and excessive harmful impurities caused by inaccurate process control in the prior art.
[0006] To achieve the above objectives, the present invention provides a process for preparing food-grade high-purity sodium pyrophosphate, comprising the following steps:
[0007] Sodium dihydrogen phosphate raw material that meets industrial-grade standards is selected, its purity is tested, and it is then pulverized to 80-120 mesh and screened to obtain refined raw material powder.
[0008] The refined raw material powder was added to deionized water at a solid-liquid mass-volume ratio of 1:2-1:3 and dissolved under heating and stirring conditions to obtain an aqueous solution of sodium dihydrogen phosphate.
[0009] Sodium hydroxide solution is added dropwise to the sodium dihydrogen phosphate aqueous solution, and the pH value is controlled at 8.5-9.5. The neutralization reaction is carried out under heating and stirring conditions to generate a sodium hydrogen phosphate intermediate solution.
[0010] The sodium hydrogen phosphate intermediate solution was placed in a reaction vessel and subjected to a polymerization and dehydration reaction at 160-180℃ and 0.1-0.3MPa to obtain a crude sodium pyrophosphate solution.
[0011] After cooling the crude sodium pyrophosphate solution, activated carbon was added for decolorization and filtration. Then, the filtrate was cooled and crystallized to obtain wet sodium pyrophosphate crystals.
[0012] The wet sodium pyrophosphate crystals are dried and then pulverized to the target particle size to obtain food-grade high-purity sodium pyrophosphate.
[0013] The raw material, sodium dihydrogen phosphate, meeting industrial-grade standards, was selected, its purity tested, and then pulverized to 80-120 mesh. The refined raw material powder obtained through screening includes:
[0014] The main content of the sodium dihydrogen phosphate raw material is ≥98%.
[0015] Specifically, the refined raw material powder is added to deionized water at a solid-liquid mass-to-volume ratio of 1:2-1:3 and dissolved under heating and stirring conditions to obtain an aqueous solution of sodium dihydrogen phosphate, which includes:
[0016] Add the refined raw material powder to deionized water and keep it at 50-70℃ and stirring speed of 200-300r / min for 30-60 minutes to ensure it is fully dissolved.
[0017] The process involves adding the refined raw material powder to deionized water at a solid-liquid mass-to-volume ratio of 1:2 to 1:3, dissolving it under heating and stirring conditions to obtain an aqueous solution of sodium dihydrogen phosphate. Specifically, the process also includes:
[0018] After dissolution, add 0.1%-0.3% of the raw material mass of heavy metal removal agent to the sodium dihydrogen phosphate aqueous solution and stir for 20-30 minutes.
[0019] The process involves adding sodium hydroxide solution dropwise to the sodium dihydrogen phosphate aqueous solution, controlling the pH value to 8.5-9.5, and carrying out a neutralization reaction under heating and stirring conditions to generate a disodium hydrogen phosphate intermediate solution, specifically including:
[0020] Add a 20%-30% sodium hydroxide solution dropwise to the sodium dihydrogen phosphate aqueous solution, controlling the dropping rate to 1-2 L / h, and react for 60-90 min at 50-70℃ and a stirring speed of 150-250 r / min.
[0021] The process involves placing the disodium hydrogen phosphate intermediate solution in a reaction vessel and carrying out a polymerization and dehydration reaction at 160-180℃ and 0.1-0.3 MPa to obtain a crude sodium pyrophosphate solution, specifically comprising:
[0022] The sodium hydrogen phosphate intermediate solution was reacted at 160-180℃ and 0.1-0.3MPa for 2-4 hours with a stirring speed of 100-150 r / min.
[0023] The process involves cooling the crude sodium pyrophosphate solution, adding activated carbon for decolorization, filtering, and then cooling the filtrate to crystallize, yielding wet sodium pyrophosphate crystals. Specifically, this includes:
[0024] The crude sodium pyrophosphate solution is cooled to 80-100℃, and 0.2%-0.5% of activated carbon by mass is added. After stirring and adsorption for 30-45 minutes, it is then filtered precisely.
[0025] The filtered clear liquid was cooled to 20-30℃ at a rate of 5-10℃ / h and crystallized at the same temperature for 12-18h to obtain crystals.
[0026] The crystals are centrifuged to remove the mother liquor, yielding the wet sodium pyrophosphate crystals.
[0027] Specifically, the process of drying the wet sodium pyrophosphate crystals and then pulverizing them to the target particle size to obtain food-grade high-purity sodium pyrophosphate product includes:
[0028] The drying process is vacuum drying, with drying conditions of 100-120℃, vacuum degree of -0.08~-0.09MPa, and time of 4-6h.
[0029] The process of drying the wet sodium pyrophosphate crystals and then pulverizing them to the target particle size to obtain food-grade high-purity sodium pyrophosphate product specifically includes:
[0030] The target particle size for the pulverization is 100-150 mesh.
[0031] The present invention discloses a preparation process for food-grade high-purity sodium pyrophosphate, which includes the following steps in sequence: raw material screening and pretreatment, batching and dissolution, neutralization reaction, polymerization and dehydration, purification and refining, drying and pulverization. By controlling the purity (main content ≥98%) and particle size (80-120 mesh) of the raw material sodium dihydrogen phosphate, the temperature (50-70℃), pH value (8.5-9.5) and stirring parameters during the dissolution and neutralization stages, and by introducing a heavy metal removal agent after dissolution, and by using process conditions of 160-180℃ and 0.1-0.3MPa during the polymerization stage, combined with activated carbon decolorization, precision filtration, programmed cooling crystallization, and vacuum drying and ultrafine pulverization, a complete and controllable preparation process is formed. This technology effectively solves the problems of insufficient product purity and excessive residues of harmful impurities (such as heavy metals) caused by inaccurate process control in existing technologies. It achieves efficient preparation and deep purification of sodium pyrophosphate, making the product purity stably reach over 96.5% and significantly reducing the impurity content, thereby meeting the food industry's demand for high-purity and high-safety additives. Attached Figure Description
[0032] To more clearly illustrate the technical solutions in the embodiments of this application or the prior art, the accompanying drawings used in the description of the embodiments or the prior art will be briefly introduced below.
[0033] Figure 1 This is a flowchart of the preparation process of food-grade high-purity sodium pyrophosphate according to the present invention. Detailed Implementation
[0034] The embodiments of the present invention are described in detail below. Examples of the embodiments are shown in the accompanying drawings. The embodiments described below with reference to the accompanying drawings are exemplary and intended to explain the present invention, but should not be construed as limiting the present invention.
[0035] Please see Figure 1 This invention provides a process for preparing food-grade high-purity sodium pyrophosphate, comprising the following steps:
[0036] S101: Select sodium dihydrogen phosphate raw material that meets industrial-grade standards, test its purity, pulverize it to 80-120 mesh, and screen it to obtain refined raw material powder;
[0037] Specifically, raw material screening and pretreatment: Sodium dihydrogen phosphate that meets industrial-grade standards is selected as raw material. The purity of the raw material is tested to ensure that its main content is ≥98%, and the content of impurities such as heavy metals and chlorides meets the pretreatment requirements. The raw material is crushed to a particle size of 80-120 mesh, and mechanical impurities and large particles are removed by airflow screening to obtain refined raw material powder.
[0038] S102: The refined raw material powder is added to deionized water at a solid-liquid mass-volume ratio of 1:2-1:3 and dissolved under heating and stirring conditions to obtain an aqueous solution of sodium dihydrogen phosphate.
[0039] Specifically, the preparation and dissolution process is as follows: The refined raw material powder is added to deionized water at a solid-liquid ratio of 1:2-1:3 (mass-volume ratio, g / mL). The stirring device is started, and the stirring speed is adjusted to 200-300 r / min. The mixture is heated to 50-70℃ and stirred for 30-60 min to ensure complete dissolution of the raw material, yielding a sodium dihydrogen phosphate aqueous solution. 0.1%-0.3% of a heavy metal removal agent (by weight of the raw material) is added to the solution, and the mixture is stirred for 20-30 min to remove heavy metal impurities from the solution.
[0040] S103: Add sodium hydroxide solution dropwise to the sodium dihydrogen phosphate aqueous solution, control the pH value to 8.5-9.5, and carry out a neutralization reaction under heating and stirring conditions to generate a sodium hydrogen phosphate intermediate solution;
[0041] Specifically, the neutralization reaction is as follows: Sodium dihydrogen phosphate aqueous solution is introduced into the neutralization reaction vessel, and sodium hydroxide solution with a mass fraction of 20%-30% is slowly added dropwise at a rate of 1-2 L / h. At the same time, the pH value of the reaction system is monitored in real time and kept stable at 8.5-9.5. During the reaction, the temperature is maintained at 50-70℃, the stirring speed is 150-250 r / min, and the reaction is carried out for 60-90 min to generate disodium hydrogen phosphate intermediate solution.
[0042] S104: The sodium hydrogen phosphate intermediate solution is placed in a reaction vessel and subjected to polymerization and dehydration reaction at 160-180℃ and 0.1-0.3MPa to obtain crude sodium pyrophosphate solution.
[0043] Specifically, the polymerization dehydration process involves transferring the disodium hydrogen phosphate intermediate solution into a polymerization reactor, heating it to 160-180℃, controlling the reaction pressure at 0.1-0.3MPa, and carrying out the polymerization dehydration reaction. During the reaction, continuous stirring is maintained at a speed of 100-150 r / min, and the reaction time is 2-4 h, so that the disodium hydrogen phosphate is dehydrated and polymerized to produce a crude sodium pyrophosphate solution.
[0044] S105: After cooling the crude sodium pyrophosphate solution, activated carbon is added for decolorization and filtration. Then, the filtrate is cooled and crystallized to obtain wet sodium pyrophosphate crystals.
[0045] Specifically, the purification process involves cooling the crude sodium pyrophosphate solution to 80-100℃, adding 0.2%-0.5% activated carbon decolorizing agent by mass of the solution, stirring and adsorbing for 30-45 minutes, and then filtering through a precision filter to remove activated carbon and trace suspended solids. The filtered clear liquid is then transferred to a crystallizer and cooled to 20-30℃ at a cooling rate of 5-10℃ / h, and crystallized at a constant temperature for 12-18 hours to obtain sodium pyrophosphate crystals. The crystals are then centrifuged to remove the mother liquor, yielding wet crystals.
[0046] S106: The wet sodium pyrophosphate crystals are dried and then pulverized to the target particle size to obtain food-grade high-purity sodium pyrophosphate product.
[0047] Specifically, drying and pulverizing: wet crystals are placed in a vacuum drying oven, the drying temperature is controlled at 100-120℃, the vacuum degree is -0.08~-0.09MPa, and the drying time is 4-6 hours to remove moisture; the dried crystals are then ultra-finely pulverized to a particle size of 100-150 mesh to obtain food-grade high-purity sodium pyrophosphate.
[0048] By optimizing the process parameters throughout the entire process, including raw material pretreatment, neutralization reaction, polymerization dehydration, and purification, sodium pyrophosphate was produced with high efficiency and deep purification. The product purity was steadily increased to ≥96.5%, and the content of impurities such as heavy metals and chlorides strictly met the requirements of the National Food Safety Standard for Food Additives Sodium Pyrophosphate (GB1886.339-2021). The quality is superior to products produced by traditional processes and can meet the food industry's demand for high-quality additives.
[0049] This invention adds a special heavy metal removal agent during the raw material dissolution stage and uses a combination of activated carbon decolorization and precision filtration during the purification stage, which greatly improves the efficiency of impurity removal and effectively solves the technical pain point of the difficulty in completely removing impurities in traditional processes, thus ensuring the safety and stability of the product.
[0050] The above-disclosed embodiments are merely one or more preferred embodiments of this application and should not be construed as limiting the scope of this application. Those skilled in the art can understand that all or part of the processes for implementing the above embodiments and equivalent changes made in accordance with the claims of this application still fall within the scope of this application.
Claims
1. A preparation process for food-grade high-purity sodium pyrophosphate, characterized in that, Includes the following steps: Sodium dihydrogen phosphate raw material that meets industrial-grade standards is selected, its purity is tested, and it is then pulverized to 80-120 mesh and screened to obtain refined raw material powder. The refined raw material powder was added to deionized water at a solid-liquid mass-volume ratio of 1:2-1:3 and dissolved under heating and stirring conditions to obtain an aqueous solution of sodium dihydrogen phosphate. Sodium hydroxide solution is added dropwise to the sodium dihydrogen phosphate aqueous solution, and the pH value is controlled at 8.5-9.
5. The neutralization reaction is carried out under heating and stirring conditions to generate a sodium hydrogen phosphate intermediate solution. The sodium hydrogen phosphate intermediate solution was placed in a reaction vessel and subjected to a polymerization and dehydration reaction at 160-180℃ and 0.1-0.3MPa to obtain a crude sodium pyrophosphate solution. After cooling the crude sodium pyrophosphate solution, activated carbon was added for decolorization and filtration. Then, the filtrate was cooled and crystallized to obtain wet sodium pyrophosphate crystals. The wet sodium pyrophosphate crystals are dried and then pulverized to the target particle size to obtain food-grade high-purity sodium pyrophosphate.
2. The preparation process of food-grade high-purity sodium pyrophosphate as described in claim 1, characterized in that, Sodium dihydrogen phosphate raw material meeting industrial-grade standards was selected, and after purity testing, it was pulverized to 80-120 mesh and screened to obtain refined raw material powder, specifically including: The main content of the sodium dihydrogen phosphate raw material is ≥98%.
3. The preparation process of food-grade high-purity sodium pyrophosphate as described in claim 1, characterized in that, The refined raw material powder is added to deionized water at a solid-liquid mass-to-volume ratio of 1:2-1:3 and dissolved under heating and stirring conditions to obtain an aqueous solution of sodium dihydrogen phosphate, specifically comprising: Add the refined raw material powder to deionized water and keep it at 50-70℃ and stirring speed of 200-300r / min for 30-60 minutes to ensure it is fully dissolved.
4. The preparation process of food-grade high-purity sodium pyrophosphate as described in claim 3, characterized in that, The refined raw material powder is added to deionized water at a solid-liquid mass-to-volume ratio of 1:2-1:3 and dissolved under heating and stirring conditions to obtain an aqueous solution of sodium dihydrogen phosphate. Specifically, the process also includes: After dissolution, add 0.1%-0.3% of the raw material mass of heavy metal removal agent to the sodium dihydrogen phosphate aqueous solution and stir for 20-30 minutes.
5. The preparation process of food-grade high-purity sodium pyrophosphate as described in claim 1, characterized in that, Sodium hydroxide solution is added dropwise to the sodium dihydrogen phosphate aqueous solution, controlling the pH value to 8.5-9.
5. A neutralization reaction is carried out under heating and stirring conditions to generate a disodium hydrogen phosphate intermediate solution, specifically including: Add a 20%-30% sodium hydroxide solution dropwise to the sodium dihydrogen phosphate aqueous solution, controlling the dropping rate to 1-2 L / h, and react for 60-90 min at 50-70℃ and a stirring speed of 150-250 r / min.
6. The preparation process of food-grade high-purity sodium pyrophosphate as described in claim 1, characterized in that, The sodium hydrogen phosphate intermediate solution was placed in a reaction vessel and subjected to a polymerization and dehydration reaction at 160-180℃ and 0.1-0.3MPa to obtain a crude sodium pyrophosphate solution, specifically comprising: The sodium hydrogen phosphate intermediate solution was reacted at 160-180℃ and 0.1-0.3MPa for 2-4 hours with a stirring speed of 100-150 r / min.
7. The preparation process of food-grade high-purity sodium pyrophosphate as described in claim 1, characterized in that, After cooling the crude sodium pyrophosphate solution, activated carbon is added for decolorization and filtration is performed. The filtrate is then cooled and crystallized to obtain wet sodium pyrophosphate crystals, specifically including: The crude sodium pyrophosphate solution is cooled to 80-100℃, and 0.2%-0.5% of activated carbon by mass is added. After stirring and adsorption for 30-45 minutes, it is then filtered precisely. The filtered clear liquid was cooled to 20-30℃ at a rate of 5-10℃ / h and crystallized at the same temperature for 12-18h to obtain crystals. The crystals are centrifuged to remove the mother liquor, yielding the wet sodium pyrophosphate crystals.
8. The preparation process of food-grade high-purity sodium pyrophosphate as described in claim 1, characterized in that, The sodium pyrophosphate wet crystals are dried and then pulverized to the target particle size to obtain a food-grade high-purity sodium pyrophosphate product, specifically comprising: The drying process is vacuum drying, with drying conditions of 100-120℃, vacuum degree of -0.08~-0.09MPa, and time of 4-6h.
9. The preparation process of food-grade high-purity sodium pyrophosphate as described in claim 1, characterized in that, The process of drying the wet sodium pyrophosphate crystals and then pulverizing them to the target particle size to obtain food-grade high-purity sodium pyrophosphate product specifically includes: The target particle size for the pulverization is 100-150 mesh.