Preparation method of spectroscopically pure diammonium hydrogen phosphate

Abstract

The invention discloses a preparation method of spectroscopically pure diammonium hydrogen phosphate, which comprises the following steps: S1, dissolving industrial grade diammonium hydrogen phosphate serving as a raw material to obtain a solution A; s2, adding a heavy metal ion remover and a chelating agent into the solution A, and stirring at room temperature to obtain a solution B; s3, adjusting the solution B to be alkaline, filtering, carrying out vacuum concentration, cooling crystallization and suction filtration on filtrate, and carrying out vacuum drying on an obtained filter cake to prepare spectrally pure grade diammonium hydrogen phosphate; the heavy metal remover is used for removing arsenic, lead or other heavy metal ions; the chelating agent is used to remove magnesium, aluminum, iron, copper or other metal ions. According to the method disclosed by the invention, the spectroscopically pure grade diammonium hydrogen phosphate with extremely high product purity can be obtained, and the content of the diammonium hydrogen phosphate in the product can be greater than or equal to 99.5 wt%. In addition, by optimizing the organic amine and adopting the iminodiacetic acid for modification, the effect of removing the metal ion impurities is further improved, so that the product purity of the obtained diammonium hydrogen phosphate is further improved.

Description

Technical Field

[0001] The invention relates to the technical field of diammonium hydrogen phosphate purification, and in particular to a method for preparing spectrally pure diammonium hydrogen phosphate. Background Art

[0002] Diammonium hydrogen phosphate (DAP) is a very important industrial product. It can be widely used in industries such as industry, food additives, medicine, electronics, and high-efficiency nitrogen-phosphorus compound fertilizers. It can also be used as a dispersant in fiber processing and dye industries. The purity of diammonium hydrogen phosphate will directly affect its application range and use value. Therefore, the preparation of high-purity diammonium hydrogen phosphate has very important economic benefits.

[0003] At present, the existing preparation process of diammonium hydrogen phosphate is mainly prepared by the reaction of wet-process phosphoric acid and ammonia. The purity of the industrial-grade diammonium hydrogen phosphate product obtained by this process is not high enough (the content generally does not exceed 99.0wt%), and the content of metal ions such as arsenic, lead, iron, magnesium, aluminum, and copper in the product is relatively high, which seriously limits its application range and use value. Summary of the invention

[0004] The object of the present invention is to provide a method for preparing spectrally pure diammonium hydrogen phosphate, which is a method for purifying diammonium hydrogen phosphate and aims to purify industrial-grade diammonium hydrogen phosphate into spectrally pure diammonium hydrogen phosphate, thereby solving the problem that the application scope and use value of the existing diammonium hydrogen phosphate are limited due to insufficient product purity.

[0005] In order to achieve the above object, the present invention is achieved through the following technical solutions:

[0006] The present invention provides a method for preparing spectrally pure diammonium hydrogen phosphate, which comprises the following steps:

[0007] S1, using industrial grade diammonium hydrogen phosphate as a raw material, dissolving it to obtain solution A;

[0008] S2, adding a heavy metal ion remover and a chelating agent to the solution A and stirring at room temperature for a suitable time to obtain a solution B;

[0009] S3, adjusting the solution B to alkalinity, then filtering the solution B, and then concentrating the filtrate under reduced pressure, cooling for crystallization, and suction filtering, and vacuum drying the obtained filter cake, thereby purifying to obtain spectrally pure diammonium hydrogen phosphate;

[0010] The heavy metal remover is used to remove arsenic, lead or other heavy metal ions; the chelating agent is used to remove magnesium, aluminum, iron, copper or other metal ions.

[0011] Furthermore, a method for preparing spectrally pure diammonium hydrogen phosphate is provided: step S1, using industrial grade diammonium hydrogen phosphate as a raw material, dissolving it in ultrapure water and stirring and dissolving it at room temperature to obtain solution A; the concentration of diammonium hydrogen phosphate in the solution A is 10.0 to 30.0 wt%.

[0012] Furthermore, a method for preparing spectrally pure diammonium hydrogen phosphate is provided: step S2, adding a heavy metal ion remover and a chelating agent to the solution A and stirring at room temperature for 4 to 8 hours to obtain a solution B; wherein the concentration of the heavy metal ion remover in the solution B is 0.1 to 0.5 wt%, and the concentration of the chelating agent is 0.5 to 5.0 wt%.

[0013] Furthermore, a method for preparing spectrally pure diammonium hydrogen phosphate: the concentration of the heavy metal ion remover in the solution B is 0.2-0.3 wt %, and the concentration of the chelating agent is 1.0-3.0 wt %.

[0014] Furthermore, a method for preparing spectrally pure diammonium hydrogen phosphate: the heavy metal ion remover in step S2 is P2S5; the chelating agent is an organic amine-modified starch chelating agent, and the organic amine is iminediacetic acid or ethylenediamine.

[0015] Furthermore, a method for preparing spectrally pure diammonium hydrogen phosphate is provided: the organic amine is iminediacetic acid.

[0016] Furthermore, a method for preparing spectrally pure diammonium hydrogen phosphate is provided: step S3, adjusting the pH value of the solution B to 7.6-9.0, and then filtering the solution B using a microfiltration membrane with a pore size of 0.1-0.3 μm, and then reducing the pressure of the filtrate to 1.0-2.0 KPa at 40-60° C. for concentration, cooling to room temperature for recrystallization, and suction filtering, and vacuum drying the obtained filter cake at 60-65° C., thereby purifying to obtain spectrally pure diammonium hydrogen phosphate.

[0017] Furthermore, a method for preparing spectrally pure diammonium hydrogen phosphate: in step S3, the pH value of solution B is adjusted to 7.6-9.0 by using ammonia water and / or phosphoric acid, the vacuum degree during vacuum drying is 0.5-2.0 KPa, and the vacuum drying time is 1-6 hours.

[0018] Furthermore, a method for preparing spectrally pure diammonium hydrogen phosphate: the content of diammonium hydrogen phosphate in the diammonium hydrogen phosphate product prepared in step S3 is ≥99.5wt%.

[0019] Beneficial effects of the present invention:

[0020] (1) The method of the present invention can obtain spectrally pure diammonium hydrogen phosphate with extremely high purity, and the content of diammonium hydrogen phosphate in the product can reach ≥99.5wt%. The method of the present invention introduces the reagent P2S5 in the recrystallization process to remove arsenic and lead impurities, and introduces an organic amine-modified starch chelating agent to remove metal ion impurities, and then recrystallizes after concentration and uses a vacuum drying process to control the clarity of the product, thereby obtaining spectrally pure diammonium hydrogen phosphate.

[0021] (2) The present invention also further improves the effect of removing metal ion impurities by optimizing the organic amine and using iminediacetic acid or ethylenediamine for modification, thereby further improving the product purity of diammonium hydrogen phosphate. DETAILED DESCRIPTION

[0022] The technical solution of the present invention will be clearly and completely described below in conjunction with specific embodiments. Obviously, the described embodiments are only part of the embodiments of the present invention, rather than all of the embodiments. The following description of at least one exemplary embodiment is actually only illustrative and is by no means intended to limit the present invention and its application or use. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0023] Example 1

[0024] This embodiment 1 provides a method for preparing spectrally pure diammonium hydrogen phosphate, which comprises the following specific steps:

[0025] S1. Using industrial-grade diammonium hydrogen phosphate (in compliance with HG / T 4132-2010 standard) as a raw material, 500.0 ml of ultrapure water and 210.0 g of industrial-grade diammonium hydrogen phosphate ((NH4)2HPO4) were added to a reaction device equipped with a stirrer and a temperature controller, and stirred and dissolved at room temperature to obtain solution A (the concentration of diammonium hydrogen phosphate in solution A was about 29.6 wt%);

[0026] S2, adding 1.9g of heavy metal ion remover (P2S5) and 8.87g of chelating agent (starch chelating agent modified by iminodiacetic acid) to the above-mentioned solution A, and stirring at room temperature for 4 hours to obtain solution B (the concentration of heavy metal ion remover in solution B is about 0.26wt%, and the concentration of chelating agent is about 1.2wt%);

[0027] S3. The solution B is adjusted to a pH value of 8.2 with ammonia water and / or phosphoric acid, and then the solution B is filtered through a microfiltration membrane with a pore size of 0.2 μm, and the filtrate is decompressed to 1.0-2.0 KPa at 50° C. to remove most of the water for concentration, cooled to room temperature for recrystallization, and then filtered. The filter cake obtained after the filtration is vacuum dried in a vacuum oven at 63° C. for 6 hours (vacuum degree is 1.0 KPa), thereby purifying to obtain spectrally pure diammonium hydrogen phosphate.

[0028] Example 2

[0029] This embodiment 2 provides a method for preparing spectrally pure diammonium hydrogen phosphate, which comprises the following specific steps:

[0030] S1. Using industrial-grade diammonium hydrogen phosphate (in compliance with HG / T 4132-2010 standard) as a raw material, 500.0 ml of ultrapure water and 125.0 g of industrial-grade diammonium hydrogen phosphate ((NH4)2HPO4) were added to a reaction device equipped with a stirrer and a temperature controller, and stirred and dissolved at room temperature to obtain solution A (the concentration of diammonium hydrogen phosphate in solution A was 20.0 wt%);

[0031] S2, adding a heavy metal ion remover (P2S5) and a chelating agent (ethylenediamine-modified starch chelating agent) to the above-mentioned solution A, and stirring at room temperature for 8 hours to obtain a solution B, wherein the concentration of the heavy metal ion remover in the solution B is about 0.12wt%, and the concentration of the chelating agent is about 0.5wt%;

[0032] S3. The solution B is adjusted to a pH value of 7.6 with ammonia water and / or phosphoric acid, and then the solution B is filtered through a microfiltration membrane with a pore size of 0.15 μm, and the filtrate is decompressed to 1.0-2.0 KPa at 40° C. to remove most of the water for concentration, cooled to room temperature for recrystallization, and then filtered, and the filter cake obtained after filtration is vacuum dried in a vacuum oven at 60° C. for 4 hours (vacuum degree is 2.0 KPa), thereby purifying to obtain spectrally pure diammonium hydrogen phosphate.

[0033] Example 3

[0034] This embodiment 3 provides a method for preparing spectrally pure diammonium hydrogen phosphate, which comprises the following specific steps:

[0035] S1. Using industrial-grade diammonium hydrogen phosphate (in compliance with HG / T 4132-2010 standard) as a raw material, 500.0 ml of ultrapure water and 75.0 g of industrial-grade diammonium hydrogen phosphate ((NH4)2HPO4) were added to a reaction device equipped with a stirrer and a temperature controller, and stirred and dissolved at room temperature to obtain solution A (the concentration of diammonium hydrogen phosphate in solution A was 13.0 wt%);

[0036] S2, adding a heavy metal ion remover (P2S5) and a chelating agent (a starch chelating agent modified with iminodiacetic acid) to the above-mentioned solution A, and stirring at room temperature for 6 hours to obtain a solution B, wherein the concentration of the heavy metal ion remover in the solution B is about 0.45wt%, and the concentration of the chelating agent is about 4.5wt%;

[0037] S3. The solution B is adjusted to a pH value of 8.7 with ammonia water and / or phosphoric acid, and then the solution B is filtered through a microfiltration membrane with a pore size of 0.22 μm, and the filtrate is decompressed to 1.0-2.0 KPa at 60° C. to remove most of the water for concentration, cooled to room temperature for recrystallization, and then filtered, and the filter cake obtained after the filtration is vacuum dried in a vacuum oven at 65° C. for 4 hours (vacuum degree is 0.5 KPa), thereby purifying to obtain spectrally pure diammonium hydrogen phosphate.

[0038] Comparative Example 1

[0039] Comparative Example 1 also provides a method for preparing diammonium hydrogen phosphate, which comprises the following specific steps:

[0040] S1. Using industrial-grade diammonium hydrogen phosphate (in compliance with HG / T 4132-2010 standard) as a raw material, 500.0 ml of ultrapure water and 210.0 g of industrial-grade diammonium hydrogen phosphate ((NH4)2HPO4) were added to a reaction device equipped with a stirrer and a temperature controller, and stirred and dissolved at room temperature to obtain solution A (the concentration of diammonium hydrogen phosphate in solution A was about 29.6 wt%);

[0041] S2, adding 1.9g of heavy metal ion remover (P2S5) and 8.87g of chelating agent (starch chelating agent modified by iminodiacetic acid) to the above-mentioned solution A, and stirring at room temperature for 4 hours to obtain solution B (the concentration of heavy metal ion remover in solution B is about 0.26wt%, and the concentration of chelating agent is about 1.2wt%);

[0042] S3. The solution B is adjusted to a pH value of 8.2 with ammonia water and / or phosphoric acid, and then the solution B is filtered through a microfiltration membrane with a pore size of 0.2 μm, and the filtrate is decompressed to 1.0-2.0 KPa at 50° C. to remove most of the water for concentration, cooled to room temperature for recrystallization, and then filtered with suction, and the filter cake obtained after the filtration is dried at 63° C. for 6 hours, thereby obtaining diammonium hydrogen phosphate.

[0043] The difference between the comparative example 1 and the embodiment 1 is that the comparative example 1 does not perform vacuum drying but adopts a conventional drying method.

[0044] Comparative Example 2

[0045] Comparative Example 2 provides a method for preparing diammonium hydrogen phosphate, which comprises the following specific steps:

[0046] S1. Using industrial-grade diammonium hydrogen phosphate (in compliance with HG / T 4132-2010 standard) as a raw material, 500.0 ml of ultrapure water and 210.0 g of industrial-grade diammonium hydrogen phosphate ((NH4)2HPO4) were added to a reaction device equipped with a stirrer and a temperature controller, and stirred and dissolved at room temperature to obtain solution A (the concentration of diammonium hydrogen phosphate in solution A was about 29.6 wt%);

[0047] S2, adding 1.9g of heavy metal ion remover (P2S5) and 8.87g of chelating agent (diethanolamine-modified starch chelating agent) to the above-mentioned solution A, and stirring at room temperature for 4 hours to obtain solution B (the concentration of heavy metal ion remover in solution B is about 0.26wt%, and the concentration of chelating agent is about 1.2wt%);

[0048] S3. The solution B is adjusted to a pH value of 8.2 with ammonia water and / or phosphoric acid, and then the solution B is filtered through a microfiltration membrane with a pore size of 0.2 μm, and the filtrate is decompressed to 1.0-2.0 KPa at 50° C. to remove most of the water for concentration, cooled to room temperature for recrystallization, and then filtered by suction. The filter cake obtained after the filtration is vacuum dried in a vacuum oven at 63° C. for 6 hours (vacuum degree is 1.0 KPa), thereby purifying to obtain diammonium hydrogen phosphate.

[0049] The difference between the comparative example 2 and the embodiment 1 is that the organic amine used in the comparative example 2 is diethanolamine, that is, the starch chelating agent is modified by the organic amine (imidodiacetic acid) different from that in the embodiment 1; the other conditions are the same as those in the embodiment 1.

[0050] Comparative Example 3

[0051] Comparative Example 3 provides a method for preparing diammonium hydrogen phosphate, which comprises the following specific steps:

[0052] S1. Using industrial-grade diammonium hydrogen phosphate (in compliance with HG / T 4132-2010 standard) as a raw material, 500.0 ml of ultrapure water and 210.0 g of industrial-grade diammonium hydrogen phosphate ((NH4)2HPO4) were added to a reaction device equipped with a stirrer and a temperature controller, and stirred and dissolved at room temperature to obtain solution A (the concentration of diammonium hydrogen phosphate in solution A was about 29.6 wt%);

[0053] S2, adding 1.9g of heavy metal ion remover (P2S5) and 8.87g of chelating agent (p-phenylenediamine-modified starch chelating agent) to the above-mentioned solution A, and stirring at room temperature for 4 hours to obtain solution B (the concentration of heavy metal ion remover in solution B is about 0.26wt%, and the concentration of chelating agent is about 1.2wt%);

[0054] S3. The solution B is adjusted to a pH value of 8.2 with ammonia water and / or phosphoric acid, and then the solution B is filtered through a microfiltration membrane with a pore size of 0.2 μm, and the filtrate is decompressed to 1.0-2.0 KPa at 50° C. to remove most of the water for concentration, cooled to room temperature for recrystallization, and then filtered by suction. The filter cake obtained after the filtration is vacuum dried in a vacuum oven at 63° C. for 6 hours (vacuum degree is 1.0 KPa), thereby purifying to obtain diammonium hydrogen phosphate.

[0055] The difference between the comparative example 3 and the example 1 is that the organic amine used in the comparative example 3 is p-phenylenediamine, that is, the starch chelating agent is modified by an organic amine (imidodiacetic acid) different from that in the example 1; the other conditions are the same as those in the example 1.

[0056] Comparative Example 4

[0057] The difference between Comparative Example 4 and Example 1 is that the organic amine used in Comparative Example 4 is cyclohexylamine, that is, the starch chelating agent is modified by an organic amine (imidodiacetic acid) different from that in Example 1; the other conditions are the same as those in Example 1.

[0058] Comparative Example 5

[0059] The difference between Comparative Example 5 and Example 1 is that the organic amine used in Comparative Example 5 is polyethyleneimine, that is, the starch chelating agent is modified by an organic amine (imidodiacetic acid) different from that in Example 1 in Comparative Example 5; the other conditions are the same as those in Example 1.

[0060] test:

[0061] The diammonium hydrogen phosphate obtained in the above Example 1 and Comparative Examples 1 to 5 was tested for indicators such as "content", "clarity", "chloride", "nitrate", "arsenic" and other "cations", and the results are shown in Table 1:

[0062] Table 1 is the test results of diammonium hydrogen phosphate obtained in Example 1 and Comparative Examples 1 to 5

[0063] content Clarity chloride / % Nitrate / % arsenic / % cation Example 1 99.6wt% ＜3 ＜0.0005 ＜0.0005 0.0001 qualified Comparative Example 1 99.5wt% 4 ＜0.0005 ＜0.0005 0.0002 qualified Comparative Example 2 98.6wt% ＜3 ＜0.0005 ＜0.0005 0.00033 Failure Comparative Example 3 98.5wt% ＜3 ＜0.0005 ＜0.0005 0.00029 Failure Comparative Example 4 98.9wt% ＜3 ＜0.0005 ＜0.0005 0.00037 Failure Comparative Example 5 98.7wt% ＜3 ＜0.0005 ＜0.0005 0.00026 Failure

[0064] Note: The content in the above table refers to the actual content of diammonium hydrogen phosphate in the diammonium hydrogen phosphate product. The requirements for the above indicators of spectrally pure diammonium hydrogen phosphate are: content standard value ≥ 99.0wt%, clarity standard value ≤ 3, chloride standard value ≤ 0.0005%, nitrate standard value ≤ 0.0005%, arsenic standard value ≤ 0.0005%, cation qualified standard: except arsenic, single element ≤ 0.005%, total element impurities ≤ 0.02%.

[0065] It can be seen from the test results of Example 1 in Table 1 that the method of the present invention can purify industrial-grade diammonium hydrogen phosphate into spectrally pure diammonium hydrogen phosphate, and its test results meet the spectrally pure specification requirements.

[0066] It can be seen from the test results of Example 1 and Comparative Example 1 in Table 1 that the present invention can further improve the clarity of the product by adopting the vacuum drying process.

[0067] From the test results of Example 1 and Comparative Examples 2 to 5 in Table 1, it can be seen that the present invention preferably uses iminodiacetic acid as an organic amine to modify the starch chelating agent, which can further promote the removal of metal ions in the product, thereby achieving the effect of further improving the purity of the product.

[0068] The method of the present invention can obtain spectrally pure diammonium hydrogen phosphate with extremely high product purity, and the content of diammonium hydrogen phosphate in the product can reach ≥99.5wt%, and the test result meets the spectrally pure specification requirements. The present invention also further improves the effect of removing metal ion impurities by optimizing the organic amine and modifying it with iminodiacetic acid, thereby further improving the product purity of the obtained diammonium hydrogen phosphate.

[0069] The above are preferred embodiments of the present invention and are only used to explain the present invention, not to limit the present invention. Any obvious changes or modifications derived from the technical solution of the present invention are still within the protection scope of the present invention.

Claims

1. A method for preparing spectrally pure diammonium hydrogen phosphate, characterized in that: The method comprises the following steps: S1, using industrial grade diammonium hydrogen phosphate as a raw material, dissolving it to obtain solution A; S2, adding a heavy metal ion remover and a chelating agent to the solution A and stirring at room temperature for a suitable time to obtain a solution B; S3, adjusting the solution B to alkalinity, then filtering the solution B, and then concentrating the filtrate under reduced pressure, cooling for crystallization, and suction filtering, and vacuum drying the obtained filter cake, thereby purifying to obtain spectrally pure diammonium hydrogen phosphate; The heavy metal remover is used to remove arsenic, lead or other heavy metal ions; the chelating agent is used to remove magnesium, aluminum, iron, copper or other metal ions.

2. The method for preparing spectrally pure diammonium hydrogen phosphate according to claim 1, characterized in that: Step S1, using industrial grade diammonium hydrogen phosphate as a raw material, dissolving it in ultrapure water and stirring to dissolve at room temperature to obtain a solution A; Wherein, the concentration of diammonium hydrogen phosphate in the solution A is 10.0-30.0 wt %.

3. The method for preparing spectrally pure diammonium hydrogen phosphate according to claim 1, characterized in that: Step S2, adding a heavy metal ion remover and a chelating agent to the solution A and stirring at room temperature for 4 to 8 hours to obtain a solution B; Wherein, the concentration of the heavy metal ion remover in the solution B is 0.1-0.5 wt %, and the concentration of the chelating agent is 0.5-5.0 wt %.

4. The method for preparing spectrally pure diammonium hydrogen phosphate according to claim 3, characterized in that: The concentration of the heavy metal ion remover in the solution B is 0.2-0.3 wt %, and the concentration of the chelating agent is 1.0-3.0 wt %.

5. A method for preparing spectrally pure diammonium hydrogen phosphate according to claim 1 or 3, characterized in that: The heavy metal ion remover in step S2 is P2S5; the chelating agent is starch chelating agent modified by organic amine, and the organic amine is iminediacetic acid or ethylenediamine.

6. The method for preparing spectrally pure diammonium hydrogen phosphate according to claim 5, characterized in that: The organic amine is iminodiacetic acid.

7. The method for preparing spectrally pure diammonium hydrogen phosphate according to claim 1, characterized in that: Step S3, adjusting the pH value of the solution B to 7.6-9.0, and then filtering the solution B using a microfiltration membrane with a pore size of 0.1-0.3 μm, and then reducing the filtrate to 1.0-2.0 KPa at 40-60° C. for concentration, cooling to room temperature for recrystallization, and suction filtering, and vacuum drying the obtained filter cake at 60-65° C. to purify and obtain spectrally pure diammonium hydrogen phosphate.

8. A method for preparing spectrally pure diammonium hydrogen phosphate according to claim 1 or 7, characterized in that: In step S3, the pH value of solution B is adjusted to 7.6-9.0 by using ammonia water and / or phosphoric acid, the vacuum degree during vacuum drying is 0.5-2.0 KPa, and the vacuum drying time is 1-6 hours.

9. The method for preparing spectrally pure diammonium hydrogen phosphate according to claim 1, characterized in that: The content of diammonium hydrogen phosphate in the diammonium hydrogen phosphate product prepared in step S3 is ≥99.5wt%.