Chemical metal impurity purification method

Abstract

In order to solve the problem that the metal ion impurity level is difficult to control in the existing chemical ion exchange resin purification method, the invention provides a chemical metal impurity purification method which comprises the following operation steps: pretreating strong acid type cationic resin by adopting a strong acid type pretreatment solution; carrying out cation exchange treatment on the to-be-purified to-be-treated liquid through the pretreated strong acid type cation resin to obtain a purified treated liquid; the pretreatment and cation exchange treatment process meets the following condition: 28.9 < = < = 11330.6. The chemical metal impurity purification method provided by the invention provides a guidance basis for chemical metal impurity purification, directional parameter control can be performed according to the purification purpose, material use and waste liquid generation can be reduced, the production cost is well reduced, the purification quality of the to-be-treated liquid is improved, and the chemical metal impurity purification method is suitable for industrial production. And treating fluid with extremely low metal impurity content is obtained.

Description

Technical Field

[0001] This invention belongs to the field of chemical purification technology and relates to a method for purifying metallic impurities in chemicals. Background Technology

[0002] Ion exchange resins are insoluble polymers with functional groups (active groups that exchange ions), a network structure, and wide applications in water treatment, catalysis, sugar refining, and pharmaceuticals. In IC (integrated circuit) manufacturing processes, cleaning agents, stripping solutions, and polishing fluids require high purity. Ion exchange resins can be used to purify these high-purity chemicals, demonstrating significant development potential.

[0003] Different resin treatment methods determine the specifications that the purified product can achieve. In IC manufacturing processes, impurities such as metals, organic matter, and particles may remain on or inside the IC, causing circuit contamination and even leading to performance degradation. To achieve better impurity removal and minimal secondary contamination, advanced processes place increasingly higher demands on cleaning agents. For single-component cleaning agents, such as hydrogen peroxide, ammonia, and isopropanol, the requirements for metal impurities are even at the G6 level (≤1ppt). For universal and additive-containing compound cleaning agents, such as BOE, HNA, and organic acid-based cleaning agents, the requirements for metal impurities are also higher than the G3 level. Therefore, with the development of processes, the demand for ultra-high purity chemicals with lower metal impurities, such as hydrogen peroxide, isopropanol, and organic acids, will increase significantly. The conventional purification method for ultra-high purity chemicals is ion exchange resin. In existing patents, mixed bed resin (CN117185918A) or H-type strong acid cation exchange resin (CN114890889A) are commonly used, but they can generally only purify organic acid metal impurities to below 10 ppb, and specific resins are used. Summary of the Invention

[0004] To address the problem that existing methods for purifying chemicals using ion exchange resins are difficult to control the level of metal ion impurities, this invention provides a method for purifying metal impurities in chemicals.

[0005] The technical solution adopted by the present invention to solve the above-mentioned technical problems is as follows: This invention provides a method for purifying metallic impurities in chemicals, comprising the following steps: The strong acid cation exchange resin was pretreated using a strong acid pretreatment solution. The solution to be purified is subjected to cation exchange treatment through a pretreated strong acid cation exchange resin to obtain the purified solution. The pretreatment and cation exchange processes must meet the following conditions: 28.9≤ ≤11330.6 Where pKa is the acid dissociation constant of the solute in the solution to be treated; V H This represents the total volume of the strong acid pretreatment solution, in mL. C H The hydrogen ion concentration of the strong acid pretreatment solution is expressed in mol / L. V R This represents the total volume of the strong acid cation exchange resin, in mL. V C The volume of the liquid to be treated is in mL. w represents the content of metal impurities in the solution to be treated, in ppb. K is a constant, with a value ranging from 0.5 to 1.2.

[0006] Optionally, the pretreatment and cation exchange processes may meet the following conditions: 28.9≤ ≤461.8; or 461.8 ≤7376.5; or 7376.5 ≤11330.6.

[0007] Optionally, the acid dissociation constant pKa of the solute in the solution to be treated is 3~12.

[0008] Optionally, the hydrogen ion concentration C of the strong acid pretreatment solution... H The concentration is 0.1~3 mol / L.

[0009] Optionally, the ratio V of the total volume of the strong acid pretreatment solution to the total volume of the strong acid cation exchange resin is... H / V R The range is 1 to 15.

[0010] Optionally, the ratio V of the volume of the liquid to be treated to the total volume of the strong acid cation exchange resin is... C / V R The range is 1 to 200.

[0011] Optionally, the metal impurity content w in the liquid to be treated is 0.1~10000 ppb.

[0012] Optionally, the pretreatment method is as follows: a strong acid-type cation exchange resin is packed into a purification column; the strong acid-type pretreatment solution is passed through the purification column in reverse order at a flow rate of 1-5 BV / h; or the strong acid-type pretreatment solution is used to wash the purification column in forward or reverse order at a flow rate of 1-5 BV / h, repeated n times, where n is V. H / 2V R Take the integer part.

[0013] Optionally, the flow rate of the liquid to be treated through the strong acid cation exchange resin is 1~5 BV / h.

[0014] Optionally, the solute in the strong acid pretreatment solution includes one or more of hydrochloric acid and sulfuric acid.

[0015] According to the chemical metal impurity purification method provided by the present invention, before using a strong acid-type cation exchange resin to purify the solution by exchanging metal impurities, a strong acid-type pretreatment solution is used to pretreat the strong acid-type cation exchange resin to enhance its exchange capacity for metal impurity ions in the solution. However, there is no existing basis to guide the relationship between certain physicochemical parameters and dosage ratios of the strong acid-type pretreatment solution, the strong acid-type cation exchange resin, and the solution. In the semiconductor manufacturing field, to meet its high requirements, purification can only be ensured by over-addition. However, over-addition leads to increased material costs and increased difficulty in waste liquid treatment. Furthermore, over-addition of some treatment agents, such as the strong acid-type pretreatment solution, can shorten the service life of the strong acid-type cation exchange resin. To solve these problems, the inventors conducted numerous experiments on multiple influencing factors in the purification process and fitted the experimental results to find that when the acid dissociation constant pKa of the solute in the solution and the total volume V of the strong acid-type pretreatment solution are... H The hydrogen ion concentration C of the strong acid pretreatment solution H The total volume V of the strong acid type cation exchange resin R Volume V of the liquid to be treated C The content of metal impurities w in the liquid to be treated satisfies the condition 28.9 ≤ When the concentration is ≤11330.6, the liquid to be treated can be purified to G3 level and above, or even to G6 level. This formula provides guidance for the purification of metal impurities in chemicals. Targeted parameter control can be carried out according to the purpose of purification, which helps to reduce material usage and waste liquid generation, effectively reducing production costs, while improving the purification quality of the liquid to be treated and obtaining a treated liquid with extremely low metal impurity content. Detailed Implementation

[0016] To make the technical problems solved, technical solutions, and beneficial effects of the present invention clearer, the present invention will be further described in detail below with reference to embodiments. It should be understood that the specific embodiments described herein are merely illustrative of the present invention and are not intended to limit the present invention.

[0017] In the description of this invention, the terms “G3”, “G4”, “G5” and “G6” follow the standards set by SEMI (Semiconductor Equipment and Materials International) to indicate the purity level of chemicals. In Gn, n represents its standard level. Among them, the G4 level has stricter requirements for impurities than the G3 level, and so on.

[0018] This invention provides a method for purifying metallic impurities in chemicals, comprising the following steps: The strong acid cation exchange resin was pretreated using a strong acid pretreatment solution. The solution to be purified is subjected to cation exchange treatment through a pretreated strong acid cation exchange resin to obtain the purified solution. The pretreatment and cation exchange processes must meet the following conditions: 28.9≤ ≤11330.6 Where pKa is the acid dissociation constant of the solute in the solution to be treated; V H This represents the total volume of the strong acid pretreatment solution, in mL. C H The hydrogen ion concentration of the strong acid pretreatment solution is expressed in mol / L. V R This represents the total volume of the strong acid cation exchange resin, in mL. V C The volume of the liquid to be treated is in mL. w represents the content of metal impurities in the solution to be treated, in ppb. K is a constant, with a value ranging from 0.5 to 1.2.

[0019] Before using a strong acid cation exchange resin to purify the solution by exchanging metal impurities, a strong acid pretreatment solution is used to pretreat the resin to enhance its exchange capacity for metal impurity ions. However, there is no existing basis to guide the relationship between the physicochemical parameters and dosage ratios of the strong acid pretreatment solution, the strong acid cation exchange resin, and the solution. In the semiconductor manufacturing field, to meet its high requirements, purification can only be guaranteed by over-addition. However, over-addition leads to increased material costs and increased difficulty in waste liquid treatment. Furthermore, over-addition of some treatment agents, such as the strong acid pretreatment solution, can shorten the lifespan of the strong acid cation exchange resin. To solve these problems, the inventors conducted extensive experiments on multiple influencing factors in the purification process and fitted the experimental results to find that when the acid dissociation constant pKa of the solute in the solution and the total volume V of the strong acid pretreatment solution are... H The hydrogen ion concentration C of the strong acid pretreatment solution H The total volume V of the strong acid type cation exchange resin R Volume V of the liquid to be treated C The content of metal impurities w in the liquid to be treated satisfies the condition 28.9 ≤ When the concentration is ≤11330.6, the liquid to be treated can be purified to G3 level and above, or even to G6 level. This formula provides guidance for the purification of metal impurities in chemicals. Targeted parameter control can be carried out according to the purpose of purification, which helps to reduce material usage and waste liquid generation, effectively reducing production costs, while improving the purification quality of the liquid to be treated and obtaining a treated liquid with extremely low metal impurity content.

[0020] In a preferred embodiment, when the target treated solution is of grade G3, the pretreatment and cation exchange treatment processes meet the following conditions: 28.9≤ ≤461.8.

[0021] In a preferred embodiment, when the target treated solution is of grade G4, the pretreatment and cation exchange treatment processes meet the following conditions: 461.8 ≤7376.5.

[0022] In a preferred embodiment, when the target obtained treatment solution is G5 level or higher, the pretreatment and cation exchange treatment processes meet the following conditions: 7376.5 ≤11330.6.

[0023] Under the conditions provided in this invention, 28.9≤ In ≤11330.6, when The higher the a value (hereinafter referred to as 'a'), the better the purification effect on the liquid to be treated, and the highest purification effect can reach G6 level. However, the consumption of strong acid pretreatment liquid and strong acid cation exchange resin is also higher. When the a value is less than 28.9, the purification effect on metal impurities in the liquid to be treated is not good, which easily leads to more metal impurity residues. When the a value is greater than 11330.6, the further improvement of the purification effect is not obvious, and it also leads to a significant increase in material costs.

[0024] In some embodiments, the acid dissociation constant pKa of the solute in the solution to be treated is 3 to 12.

[0025] In a specific embodiment, the acid dissociation constant pKa of the solute in the solution to be treated can be any value between 3, 4, 5, 6, 7, 8, 9, 10, 11, 12 or above.

[0026] In this invention, a strong acid cation exchange resin is used to exchange metal ions in the solution to reduce its content. However, the acid dissociation constant (pKa) of the solute in the solution itself affects the adsorption of metal ions by the strong acid cation exchange resin. Therefore, it is necessary to adjust the resin according to the different acid dissociation constants (pKa) of the solutions to be treated. Adjust other parameters to meet 7376.5 < To achieve a better purification effect, the acid dissociation constant pKa of the solute in the solution to be treated is less than 3. It is more difficult to purify the metal impurity ions in it, and there is a risk that the residual metal ion concentration is large after cation exchange, making it difficult to achieve the target purity level.

[0027] In a preferred embodiment, the solute of the liquid to be treated is an organic acid or other weakly acidic substance with a certain acid dissociation constant pKa.

[0028] In some embodiments, the organic acid is selected from formic acid, acetic acid, propionic acid, butyric acid, valeric acid, 2-methylbutyric acid, hexanoic acid, 3,3-dimethylbutyric acid, 2-ethylbutyric acid, 4-methylvaleric acid, heptanoic acid, 2-methylhexanoic acid, octanoic acid, 2-ethylhexanoic acid, benzoic acid, glycolic acid, salicylic acid, glyceric acid, oxalic acid, malonic acid, succinic acid, glutaric acid, adipic acid, pimelic acid, maleic acid, phthalic acid, malic acid, tartaric acid, citric acid, and lactic acid.

[0029] In some embodiments, the hydrogen ion concentration C of the strong acid pretreatment solution H The concentration is 0.1~3 mol / L.

[0030] In a specific embodiment, the hydrogen ion concentration C of the strong acid pretreatment solution H The value is within the range of 0.1 mol / L, 0.3 mol / L, 0.4 mol / L, 0.5 mol / L, 0.7 mol / L, 0.9 mol / L, 1 mol / L, 1.1 mol / L, 1.2 mol / L, 1.3 mol / L, 1.4 mol / L, 1.5 mol / L, 1.8 mol / L, 2 mol / L, 2.2 mol / L, 2.5 mol / L, 2.8 mol / L, 3 mol / L, or any value above.

[0031] The strong acid pretreatment solution is used to activate the strong acid cation exchange resin, remove impurity cations, and ensure that the resin surface has sufficient negatively charged sites for cation adsorption, thus helping to improve the resin's exchange capacity. Therefore, the hydrogen ion concentration of the strong acid pretreatment solution is related to the activation effect of the strong acid cation exchange resin and is negatively correlated with the total volume of the strong acid pretreatment solution. When the hydrogen ion concentration C of the strong acid pretreatment solution... H If the concentration is too low, it will be difficult to fully activate the strong acid cation exchange resin; if the hydrogen ion concentration C of the strong acid pretreatment solution is too low, it will be difficult to fully activate the strong acid cation exchange resin. H If the pressure is too high, it can easily corrode the strong acid cation exchange resin, leading to a shortened service life of the strong acid cation exchange resin.

[0032] In some embodiments, the ratio V of the total volume of the strong acid pretreatment solution to the total volume of the strong acid cation exchange resin is... H / V R The range is 1 to 15.

[0033] In a specific embodiment, the ratio V of the total volume of the strong acid pretreatment solution to the total volume of the strong acid cation exchange resin is... H / V R It can be a range between any values ​​of 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15 or more.

[0034] The activation effect of strong acid cation exchange resin and V H / V R The values ​​are positively correlated; under the same hydrogen ion concentration conditions, V H / V R The higher the value, the more beneficial it is for the activation effect of strong acid cation exchange resins; however, there is also a certain threshold for its activation effect. H / V R When the value exceeds a certain amount, the activation effect on the strong acid cation exchange resin is not further improved, but instead the strong acid pretreatment solution is wasted.

[0035] In some embodiments, the ratio V of the volume of the liquid to be treated to the total volume of the strong acid cation exchange resin is... C / V R The range is 1 to 200.

[0036] In a specific embodiment, the ratio V of the volume of the liquid to be treated to the total volume of the strong acid cation exchange resin is... C / V RIt can be a range of any value between 1, 3, 8, 12, 16, 19, 20, 26, 30, 36, 40, 46, 48, 50, 54, 58, 60, 65, 70, 75, 80, 85, 90, 95, 100, 112, 116, 119, 120, 126, 130, 136, 140, 146, 148, 150, 154, 158, 160, 165, 170, 175, 180, 185, 190, 200 or more.

[0037] The metal purification effect of the solution to be treated and V C / V R The values ​​show a negative correlation, meaning that the larger the volume of the liquid to be treated, the worse the purification effect and the higher the risk of increased residual metal ion concentration; however, V C / V R Too low a value also has adverse effects, such as the inability to fully utilize strong acid cation exchange resin, thus affecting purification efficiency.

[0038] In some embodiments, the metal impurity content w in the liquid to be treated is 0.1~10000 ppb.

[0039] In a specific embodiment, the metal impurity content w in the liquid to be treated can be 0.1~10000 ppb.

[0040] If the content of metal impurities w in the solution to be treated is too low, the effect of strong acid cation exchange on improving its purity is not obvious; if the content of metal impurities w in the solution to be treated is too high, it is difficult to completely remove the metal impurities by strong acid cation exchange, and certain pretreatment is required to reduce the content of metal impurities.

[0041] In some embodiments, the metallic impurities in the liquid to be treated include one or more of aluminum, calcium, chromium, copper, iron, magnesium, manganese, nickel, potassium, sodium, zinc, cobalt, lithium, tin, gallium, barium, indium, and silver.

[0042] In some embodiments, the pretreatment method is to fill a purification column with a strong acid-type cation exchange resin.

[0043] The strong acid pretreatment solution is passed in reverse order through the purification column at a flow rate of 1-5 BV / h, or Wash the purification column with a strong acid pretreatment solution in a forward or reverse order at a flow rate of 1-5 BV / h, repeating n times, where n is the number of volumes (V). H / 2V R Take the integer part.

[0044] The constant K in the a value is related to the pretreatment method used and represents the cleaning efficiency of different pretreatment methods for strong acid cation exchange resins. The constant K in the a value differs when different pretreatment methods are used. For example, when the first pretreatment method is used, the constant K is selected from 0.7; when the second pretreatment method is used, the constant K is selected from 1.0.

[0045] In some embodiments, the purification column is selected from tertiary purification columns.

[0046] In some embodiments, the flow rate of the liquid to be treated through the strong acid cation exchange resin is 1~5 BV / h.

[0047] In some embodiments, the temperature of the pretreatment and the cation exchange treatment is between -20°C and 70°C.

[0048] In some embodiments, the solute in the strong acid pretreatment solution includes one or more of hydrochloric acid and sulfuric acid.

[0049] In some embodiments, the strong acid type cationic resin includes one or more of sulfonic acid-based cationic resin and sulfate-based cationic resin.

[0050] The present invention will be further illustrated by the following examples.

[0051] Table 1 In Table 1, α = Pretreatment method 1 is as follows: the strong acid pretreatment solution is divided into 6 equal parts. In the pretreatment, one part of the solution is used to circulate and clean the resin at 5 BV / h for 2 hours, and a total of 6 cycles are performed. Pretreatment method 2 is as follows: in the pretreatment, the pretreatment solution is passed through a three-stage purification column in reverse order at a flow rate of 1 BV / h.

[0052] Example 1 This embodiment illustrates the method for purifying metallic impurities in chemicals disclosed in this invention, including the following steps: The solution to be treated was 1 L of 20% organic acid solution with a metal impurity content of 600 ppb. 100 mL of H-type strong acid resin was packed into each of the three-stage purification columns as a strong acid cation exchange resin. G3 grade high-purity hydrochloric acid was diluted to 7% as a strong acid pretreatment solution. The strong acid cation exchange resin in the three-stage purification column was activated and pretreated with the strong acid pretreatment solution. After the resin pretreatment was completed, the organic acid solution to be purified was passed through the three-stage purification column sequentially at 1 BV / h, and the purified organic acid solution was collected.

[0053] Examples 2-14 Examples 2-14 illustrate the method for purifying metallic impurities in chemicals disclosed in this invention, and include most of the operational steps in Example 1, except that: Examples 2-14 use the acid dissociation constant pKa of the solute in the solution to be treated and the total volume V of the strong acid pretreatment solution. H The hydrogen ion concentration C of the strong acid pretreatment solution H The total volume V of the strong acid type cation exchange resin R Volume V of the liquid to be treated C The content of metal impurities w in the liquid to be treated, the pretreatment method, and the K value are shown in Examples 2-14 of Table 1.

[0054] Comparative Examples 1-6 Comparative Examples 1-6 are used to illustrate the method for purifying metallic impurities in chemicals disclosed in this invention, including most of the operational steps in Example 1, with the following differences: Comparative Examples 1-6 used the acid dissociation constant pKa of the solute in the solution to be treated and the total volume V of the strong acid pretreatment solution. H The hydrogen ion concentration C of the strong acid pretreatment solution H The total volume V of the strong acid type cation exchange resin R Volume V of the liquid to be treated C The content of metal impurities w in the liquid to be treated, the pretreatment method, and the K value are shown in Comparative Examples 1 to 6 in Table 1.

[0055] Effect test The organic acid solution obtained after cation exchange was subjected to ICP-MS testing to detect its metal impurity content, and the test results were recorded in Table 2.

[0056] Table 2 Comparing the test results of Examples 1-14 and Comparative Examples 1-6, it can be seen that in the chemical metal impurity purification method provided by the present invention, by controlling the acid dissociation constant pKa of the solute in the solution to be treated and the total volume V of the strong acid pretreatment solution, the chemical impurity purification method can achieve the desired effect. H The hydrogen ion concentration C of the strong acid pretreatment solution H The total volume V of the strong acid type cation exchange resin R Volume V of the liquid to be treated C The content of metal impurities w in the liquid to be treated satisfies the condition 28.9 ≤ When the concentration is ≤11330.6, the liquid to be treated can be purified to G3 level or above, providing guidance for the purification of metal impurities in chemicals. Targeted parameter control can be carried out according to the purpose of purification, which helps to reduce material usage and waste liquid generation, and effectively reduces production costs.

[0057] The test results from Examples 1-6 show that when the value of α satisfies 28.9 ≤ When α is ≤461.8, it is advantageous to obtain G3-level treatment fluid; as shown by the test results of Examples 7 and 8, when the α value satisfies 461.8 < When α is ≤7376.5, it is advantageous to obtain G4-level treatment fluid; as shown by the test results of Examples 9-14, when the α value satisfies 7376.5 < When the concentration is ≤11330.6, it is advantageous to obtain G5 grade treatment solution.

[0058] The test results of Comparative Examples 1-3 show that when the α value is below 28.9, the purified solution prepared by this method can only reach the G1 or G2 level, which is difficult to meet the requirements of some application fields with high requirements for metal impurity content. The test results of Comparative Examples 4-6 show that when the α value exceeds 11330.6, there is no significant improvement in the purification effect of the purified solution. Moreover, based on the amount of strong acid pretreatment solution, strong acid cation exchange resin, and solution to be treated, the amount of metal impurities per unit of solution to be treated corresponds to a significant increase in the amount of strong acid pretreatment solution and strong acid cation exchange resin, resulting in a significant increase in cost.

[0059] Table 3 In Table 3, α= Pretreatment method 2 is as follows: In the pretreatment process, the pretreatment solution is passed through a three-stage purification column in reverse order at a flow rate of 1 BV / h.

[0060] Examples 15-17 Examples 15-17 illustrate the method for purifying metallic impurities in chemicals disclosed in this invention, and include most of the operational steps in Example 1, except that: Examples 15-17 use the acid dissociation constant pKa of the solute in the solution to be treated and the total volume V of the strong acid pretreatment solution. H The hydrogen ion concentration C of the strong acid pretreatment solution H The total volume V of the strong acid type cation exchange resin R Volume V of the liquid to be treated C The content of metal impurities w in the liquid to be treated, the pretreatment method, and the K value are shown in Examples 15-17 of Table 3.

[0061] Comparative Examples 7-8 Comparative Examples 7 and 8 are used to illustrate the method for purifying metallic impurities in chemicals disclosed in this invention, including most of the operational steps in Example 1, except that: Comparative Examples 7-8 used the acid dissociation constant pKa of the solute in the solution to be treated and the total volume V of the strong acid pretreatment solution. H The hydrogen ion concentration C of the strong acid pretreatment solution HThe total volume V of the strong acid type cation exchange resin R Volume V of the liquid to be treated C The content of metal impurities w in the liquid to be treated, the pretreatment method, and the K value are shown in Comparative Examples 7-8 in Table 3.

[0062] Effect test The organic acid solution obtained after cation exchange was subjected to ICP-MS testing to detect its metal impurity content. The cost of the strong acid pretreatment solution and strong acid cation exchange resin used was calculated. The test results are recorded in Table 4.

[0063] Table 4 The test results of Examples 15-17 and Comparative Examples 7-8 show that as the α value increases, the removal effect of metal impurities in the treatment solution also increases. However, when the α value exceeds 11330.6, there is no significant improvement in the purification effect of the treatment solution, and the purification cost increases significantly, indicating that there is an over-treatment problem at this time.

[0064] The above description is merely a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions, and improvements made within the spirit and principles of the present invention should be included within the protection scope of the present invention.

Claims

1. A method for purifying metallic impurities in chemicals, characterized in that, The following steps are included: The strong acid cation exchange resin was pretreated using a strong acid pretreatment solution. The solution to be purified is subjected to cation exchange treatment through a pretreated strong acid cation exchange resin to obtain the purified solution. The pretreatment and cation exchange processes must meet the following conditions: 28.9≤ ≤11330.6 Where pKa is the acid dissociation constant of the solute in the solution to be treated; V H This represents the total volume of the strong acid pretreatment solution, in mL. C H The hydrogen ion concentration of the strong acid pretreatment solution is expressed in mol / L. V R This represents the total volume of the strong acid cation exchange resin, in mL. V C The volume of the liquid to be treated is in mL. w represents the content of metal impurities in the solution to be treated, in ppb. K is a constant, with a value ranging from 0.5 to 1.

2.

2. The method for purifying metallic impurities in chemicals according to claim 1, characterized in that, The pretreatment and cation exchange processes must meet the following conditions: 28.9≤ ≤461.8； or 461.8 ≤7376.5; or 7376.5< ≤11330.6。 3. The method for purifying metallic impurities in chemicals according to claim 1, characterized in that, The acid dissociation constant pKa of the solute in the solution to be treated is 3~12.

4. The method for purifying metallic impurities in chemicals according to claim 1, characterized in that, The hydrogen ion concentration C of the strong acid pretreatment solution H The concentration is 0.1~3 mol / L.

5. The method for purifying metallic impurities in chemicals according to claim 1, characterized in that, The ratio V of the total volume of the strong acid pretreatment solution to the total volume of the strong acid cation exchange resin H / V R The range is 1 to 15.

6. The method for purifying metallic impurities in chemicals according to claim 1, characterized in that, The ratio V of the volume of the liquid to be treated to the total volume of the strong acid cation exchange resin C / V R The range is 1 to 200.

7. The method for purifying metallic impurities in chemicals according to claim 1, characterized in that, The content of metal impurities w in the liquid to be treated is 0.1~10000 ppb.

8. The method for purifying metallic impurities in chemicals according to claim 1, characterized in that, The pretreatment method is as follows: A strong acid-type cation exchange resin is packed into a purification column; the strong acid-type pretreatment solution is passed through the purification column in reverse order at a flow rate of 1-5 BV / h; or the strong acid-type pretreatment solution is used to wash the purification column in forward or reverse order at a flow rate of 1-5 BV / h. This process is repeated n times, where n is the number of BV. H / 2V R Take the integer part.

9. The method for purifying metallic impurities in chemicals according to claim 1, characterized in that, The flow rate of the liquid to be treated through the strong acid cation exchange resin is 1~5 BV / h.

10. The method for purifying metallic impurities in chemicals according to claim 1, characterized in that, The solute in the strong acid pretreatment solution includes one or more of hydrochloric acid and sulfuric acid.

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