Electronic grade boric acid and purification method and application thereof

Abstract

The invention discloses electronic grade boric acid as well as a purification method and application thereof, and belongs to the technical field of chemical processes. The purification method of the electronic grade boric acid comprises the following steps: S1, oil removal: carrying out oil removal on a boric acid crude product solution through an adsorbent to obtain boric acid oil removal liquid; and S2, ion exchange: purifying the boric acid oil removal liquid through an ion exchanger to obtain the electronic grade boric acid solution. The purification method is simple and efficient, impurities in the boric acid crude product solution can be effectively removed through the steps of oil removal and ion exchange, the electronic grade boric acid solution with low total metal impurity content and low total organic carbon content is obtained, and the electronic grade boric acid solution has stable and good use performance and is suitable for industrial production. And the method is particularly widely applied to the field of nanoscale chip integrated circuits.

Description

Technical Field

[0001] The invention belongs to the technical field of chemical processes, and in particular relates to electronic-grade boric acid and a purification method and application thereof. Background Art

[0002] Boric acid (H3BO3), as an important inorganic compound, is widely used in many fields such as electronics, chemicals, medicine and agriculture. In the electronics industry, electronic-grade boric acid is used in key steps such as cleaning, etching and doping in the semiconductor manufacturing process due to its high purity and specific physical and chemical properties.

[0003] Although boric acid is increasingly used in the electronics industry, the existing methods for producing electronic-grade boric acid still have some limitations. Traditional boric acid production methods usually involve acidification of boron ore, which is not only costly but also may introduce impurities, making it difficult to meet the high purity requirements for electronic-grade applications.

[0004] In addition, existing methods also face challenges in purifying and refining boric acid. For example, removing heavy metal ions and other organic or inorganic impurities in boric acid requires a complex purification process, which not only increases production costs but also makes it difficult to achieve good purification results. Summary of the invention

[0005] In order to overcome at least one of the problems existing in the above-mentioned prior art, one of the objects of the present invention is to provide a method for purifying boric acid, which has a simple process and obtains boric acid with high purity and low impurity content.

[0006] A second object of the present invention is to provide an electronic grade boric acid solution obtained by the above purification method.

[0007] The third object of the present invention is to provide an application of the electronic grade boric acid solution in the field of nano-scale chip integrated circuits.

[0008] In order to achieve the above object, the technical solution adopted by the present invention is:

[0009] A first aspect of the present invention provides a method for purifying electronic grade boric acid, comprising the following steps:

[0010] S1. Deoiling: Deoiling the crude boric acid solution through an adsorbent to obtain a boric acid deoiled solution;

[0011] S2. Ion exchange: purifying the boric acid degreasing liquid through an ion exchanger to obtain an electronic grade boric acid solution.

[0012] In the purification method of the present invention, the organic impurities in the crude boric acid solution can be effectively removed through the oil removal step, so that the total organic carbon (TOC) content in the obtained boric acid deoiled liquid is greatly reduced; the metal impurities in the solution can be effectively removed through the ion exchange step, so that the total content of metal impurities in the obtained electronic-grade boric acid solution is greatly reduced, and the electronic-grade boric acid solution finally obtained has a low total content of metal impurities and a low total organic carbon content.

[0013] In some specific embodiments of the present invention, in step S1, the concentration B of the crude boric acid solution is 2 to 20 g / L.

[0014] In some specific embodiments of the present invention, in step S1, the crude boric acid solution contains metal impurities and / or organic impurities.

[0015] In some specific embodiments of the present invention, in step S1, the metal impurities in the crude boric acid solution include at least one element of Ca, Cd, Cr, Fe, Mg, Mn, Mo, Na, Ni, Zn, Al, As, Cu, Pb, K, Au, Ti, In, Sn, Tl or Hg.

[0016] In some specific embodiments of the present invention, in step S1, the total content of metal impurities in the crude boric acid solution is ≥500 μg / L.

[0017] In some specific embodiments of the present invention, in step S1, the total organic carbon content in the crude boric acid solution is ≥8 mg / L.

[0018] In some specific embodiments of the present invention, in step S1, the adsorbent is activated carbon.

[0019] In some specific embodiments of the present invention, the activated carbon is obtained by an impurity removal method comprising the following steps: primary cleaning: using dilute sulfuric acid to clean the activated carbon raw material and soaking it for 20 to 30 hours to obtain primary activated carbon; secondary cleaning: using ultrapure water to clean the primary activated carbon to obtain secondary activated carbon and a water washing liquid, and this step is cleaned until the conductivity of the water washing liquid is ≤10μS; tertiary cleaning: using a boric acid solution to clean the secondary activated carbon to obtain activated carbon and a boric acid washing liquid after impurities are removed, and this step is cleaned until the difference between the total content of metal impurities in the boric acid washing liquid and the total content of metal impurities in the boric acid solution is ≤30μg / L.

[0020] In some specific embodiments of the present invention, in step S2, the speed at which the boric acid degreasing liquid passes through the ion exchanger is 80 to 220 L / h.

[0021] In some specific embodiments of the present invention, in step S2, the ion exchanger is selected from a cation exchange resin.

[0022] In some specific embodiments of the present invention, in step S2, the particle size of the ion exchanger is 0.3-2 mm.

[0023] In some specific embodiments of the present invention, in step S2, the exchange capacity of the ion exchanger is 10 to 30 mol / L.

[0024] The second aspect of the present invention provides an electronic grade boric acid solution obtained by the purification method described in the first aspect of the present invention.

[0025] In some specific embodiments of the present invention, the concentration of B in the electronic grade boric acid solution is 2 to 20 g / L.

[0026] In some specific embodiments of the present invention, the total content of metal impurities in the electronic grade boric acid solution is ≤100 μg / L.

[0027] In some specific embodiments of the present invention, the total organic carbon content of the electronic grade boric acid solution is ≤5 mg / L.

[0028] In some specific embodiments of the present invention, the pH value of the electronic grade boric acid solution is 3.5-5.

[0029] The third aspect of the present invention provides an application of the electronic-grade boric acid solution described in the second aspect of the present invention in the field of nano-scale chip integrated circuits.

[0030] The beneficial effects of the present invention are as follows: the purification method of the present invention is simple and efficient, and can effectively remove impurities in a crude boric acid solution through the steps of oil removal and ion exchange, thereby obtaining an electronic-grade boric acid solution with a low total content of metal impurities and a low total organic carbon content. The electronic-grade boric acid solution has stable and good performance, and is widely used, especially in the field of nano-scale chip integrated circuits. BRIEF DESCRIPTION OF THE DRAWINGS

[0031] Figure 1 Schematic diagram of the process of purifying boric acid in Example 1 of the present invention. DETAILED DESCRIPTION

[0032] Embodiments of the present invention are described in detail below. The embodiments are exemplary and are only used to explain the present invention, but are not to be construed as limiting the present invention.

[0033] A first aspect of an embodiment of the present invention provides a method for purifying boric acid, which specifically comprises the following steps:

[0034] S1. Deoiling: Deoiling the crude boric acid solution through an adsorbent to obtain a boric acid deoiled solution;

[0035] S2. Ion exchange: The boric acid degreasing liquid is purified by an ion exchanger to obtain an electronic grade boric acid solution.

[0036] In the purification method of the embodiment of the present invention, the organic impurities in the crude boric acid solution can be effectively removed through the deoiling step, so that the total organic carbon (TOC) content in the obtained boric acid deoiled liquid is greatly reduced; the metal impurities in the solution can be effectively removed through the ion exchange step, so that the total content of metal impurities in the obtained electronic-grade boric acid solution is greatly reduced, and the electronic-grade boric acid solution finally obtained has a low total content of metal impurities and a low total organic carbon content.

[0037] In some embodiments of the present invention, in step S1, the concentration of B in the crude boric acid solution is 2 to 20 g / L; in some specific embodiments of the present invention, in step S1, the concentration of B in the crude boric acid solution is 3 to 15 g / L; in some examples of the present invention, in step S1, the concentration of B in the crude boric acid solution is 5 to 10 g / L; non-limiting specific examples are 6 g / L, 7 g / L, 8 g / L or 9 g / L.

[0038] The B concentration of the crude boric acid solution refers to the concentration of the B element in the solution. The present invention controls the B concentration of the crude boric acid solution within the range of 2 to 20 g / L, which is beneficial for controlling the impurity content within a controllable range and effectively removing it through subsequent purification steps to obtain high-purity boric acid.

[0039] In some embodiments of the present invention, in step S1, the crude boric acid solution is obtained by mixing crude boric acid with water.

[0040] In some embodiments of the present invention, in the crude boric acid solution, the mass ratio of crude boric acid to water is 1:(15-35); in some specific embodiments of the present invention, in the crude boric acid solution, the mass ratio of crude boric acid to water is 1:(18-32); in some examples of the present invention, in the crude boric acid solution, the mass ratio of crude boric acid to water is 1:(20-30); non-limiting specific examples are 1:22, 1:24, 1:26 or 1:28.

[0041] The specific mass ratio of crude boric acid to water needs to be determined according to the purity of crude boric acid. The mass ratio of crude boric acid to water is adjusted so that the prepared crude boric acid solution meets the requirements, especially so that the crude boric acid solution has a specific concentration. At the same time, the purity of crude boric acid will also affect the impurity content in the purification system. If the purity of crude boric acid is high, the impurity content introduced is small, and the purification difficulty is relatively small; otherwise, the purification difficulty is relatively large.

[0042] In some embodiments of the present invention, in step S1, the crude boric acid solution contains metal impurities and / or organic impurities; in some specific embodiments of the present invention, in step S1, the crude boric acid solution contains metal impurities and organic impurities.

[0043] The metal impurities of the present invention include various metal elements that may exist in the crude boric acid.

[0044] In some embodiments of the present invention, in step S1, the metal impurities in the crude boric acid solution include at least one element of Ca, Cd, Cr, Fe, Mg, Mn, Mo, Na, Ni, Zn, Al, As, Cu, Pb, K, Au, Ti, In, Sn, Tl or Hg.

[0045] In some embodiments of the present invention, in step S1, the metal impurities in the crude boric acid solution include Ca, and the Ca element content in the crude boric acid solution is ≥200 μg / L; in some specific embodiments of the present invention, the Ca element content in the crude boric acid solution is 200-400 μg / L; in some examples of the present invention, the Ca element content in the crude boric acid solution is 300-400 μg / L; non-limiting specific examples are 320 μg / L, 340 μg / L, 360 μg / L, 380 μg / L or 390 μg / L.

[0046] In some embodiments of the present invention, in step S1, the metal impurities in the crude boric acid solution include Fe, and the Fe element content in the crude boric acid solution is ≥20 μg / L; in some specific embodiments of the present invention, the Fe element content in the crude boric acid solution is 20-50 μg / L; in some examples of the present invention, the Fe element content in the crude boric acid solution is 30-50 μg / L; non-limiting specific examples are 32 μg / L, 35 μg / L, 38 μg / L, 40 μg / L, 42 μg / L or 45 μg / L.

[0047] In some embodiments of the present invention, in step S1, the metal impurities in the crude boric acid solution include Mg, and the Mg element content in the crude boric acid solution is ≥40 μg / L; in some specific embodiments of the present invention, the Mg element content in the crude boric acid solution is 40-200 μg / L; in some examples of the present invention, the Mg element content in the crude boric acid solution is 50-100 μg / L; non-limiting specific examples are 60 μg / L, 70 μg / L, 80 μg / L or 90 μg / L.

[0048] In some embodiments of the present invention, in step S1, the metal impurities in the crude boric acid solution include Mn, and the Mn element content in the crude boric acid solution is ≥20 μg / L; in some specific embodiments of the present invention, the Mn element content in the crude boric acid solution is 20-150 μg / L; in some examples of the present invention, the Mn element content in the crude boric acid solution is 30-100 μg / L; non-limiting specific examples are 40 μg / L, 50 μg / L, 60 μg / L, 70 μg / L, 80 μg / L or 90 μg / L.

[0049] In some embodiments of the present invention, in step S1, the metal impurities in the crude boric acid solution include Na, and the Na element content in the crude boric acid solution is ≥20 μg / L; in some specific embodiments of the present invention, the Na element content in the crude boric acid solution is 20-50 μg / L; in some examples of the present invention, the Na element content in the crude boric acid solution is 30-50 μg / L; non-limiting specific examples are 32 μg / L, 35 μg / L, 38 μg / L, 40 μg / L, 42 μg / L or 45 μg / L.

[0050] In some embodiments of the present invention, in step S1, the metal impurities in the crude boric acid solution include Zn, and the Zn element content in the crude boric acid solution is ≥10 μg / L; in some specific embodiments of the present invention, the Zn element content in the crude boric acid solution is 10-50 μg / L; in some examples of the present invention, the Zn element content in the crude boric acid solution is 15-40 μg / L; non-limiting specific examples are 20 μg / L, 25 μg / L, 30 μg / L or 35 μg / L.

[0051] In some embodiments of the present invention, in step S1, the metal impurities in the crude boric acid solution include Al, and the Al element content in the crude boric acid solution is ≥30 μg / L; in some specific embodiments of the present invention, the Al element content in the crude boric acid solution is 30-55 μg / L; in some examples of the present invention, the Al element content in the crude boric acid solution is 35-55 μg / L; non-limiting specific examples are 40 μg / L, 45 μg / L, 50 μg / L or 53 μg / L.

[0052] In some embodiments of the present invention, in step S1, the metal impurities in the crude boric acid solution include K, and the K element content in the crude boric acid solution is ≥15 μg / L; in some specific embodiments of the present invention, the K element content in the crude boric acid solution is 15-50 μg / L; in some examples of the present invention, the K element content in the crude boric acid solution is 20-40 μg / L; non-limiting specific examples are 22 μg / L, 25 μg / L, 28 μg / L, 30 μg / L, 35 μg / L or 38 μg / L.

[0053] In some specific embodiments of the present invention, in step S1, the metal impurities in the crude boric acid solution include elements Ca, Fe, Mg, Mn, Na, Zn, Al, K, and at least one element of Cd, Cr, Mo, Ni, As, Cu, Pb, Au, Ti, In, Sn, Tl or Hg; in some examples of the present invention, in step S1, the metal impurities in the crude boric acid solution include elements Ca, Cr, Fe, Mg, Mn, Na, Ni, Zn, Al, As, Cu, K and Ti.

[0054] In some embodiments of the present invention, in step S1, the total content of metal impurities in the crude boric acid solution is ≥500 μg / L; in some specific embodiments of the present invention, in step S1, the total content of metal impurities in the crude boric acid solution is 500-1800 μg / L; in some examples of the present invention, in step S1, the total content of metal impurities in the crude boric acid solution is 550-1500 μg / L; non-limiting specific examples are 600 μg / L, 700 μg / L, 800 μg / L, 900 μg / L, 1000 μg / L, 1200 μg / L or 1400 μg / L.

[0055] In some embodiments of the present invention, in step S1, the crude boric acid solution contains organic impurities. The total content of organic impurities is represented by the total organic carbon (TOC) content.

[0056] In some embodiments of the present invention, in step S1, the total organic carbon content in the crude boric acid solution is ≥8 mg / L; in some specific embodiments of the present invention, in step S1, the total organic carbon content in the crude boric acid solution is 8-15 mg / L; in some examples of the present invention, in step S1, the total organic carbon content in the crude boric acid solution is 9-14 mg / L; non-limiting specific examples are 10 mg / L, 11 mg / L, 12 mg / L or 13 mg / L.

[0057] In some embodiments of the present invention, in step S1, the crude boric acid solution includes the following components:

[0058] B 2~20g / L Total Organic Carbon (TOC) ≥8 mg / L Metal impurities ≥500 μg / L

[0059] In some specific embodiments of the present invention, in step S1, the crude boric acid solution includes the following components:

[0060]

[0061]

[0062] In some examples of the present invention, in step S1, the crude boric acid solution includes the following components:

[0063] B 2~20g / L Total Organic Carbon (TOC) 9~14mg / L Metal impurities 550~1500μg / L

[0064] In some specific examples of the present invention, in step S1, the crude boric acid solution includes the following components:

[0065] B 2~20g / L Total Organic Carbon (TOC) 9~14mg / L Ca 200~400μg / L Cd 0.001~100μg / L Cr 0.1~100μg / L Fe 20~50μg / L Mg 40~200μg / L Mn 20~150μg / L Mo 0.001~50μg / L Na 20~50μg / L Ni 1~50μg / L Zn 10~50μg / L Al 30~55μg / L As 1~50μg / L Cu 0.01~50μg / L Pb 0.001~50μg / L K 15~50μg / L Au 0.001~50μg / L Ti 0.1~50μg / L In 0.001~50μg / L Sn 0.001~50μg / L Tl 0.001~50μg / L Hg 0.001~50μg / L

[0066] In some embodiments of the present invention, in step S1, the adsorbent is activated carbon.

[0067] In some embodiments of the present invention, in step S1, activated carbon is obtained by an impurity removal method comprising the following steps: primary cleaning: using dilute sulfuric acid to clean the activated carbon raw material and soaking it for 20 to 30 hours to obtain primary activated carbon; secondary cleaning: using ultrapure water to clean the primary activated carbon to obtain secondary activated carbon and a water washing liquid, and this step is performed until the conductivity of the water washing liquid is ≤10μS; tertiary cleaning: using a boric acid solution to clean the secondary activated carbon to obtain activated carbon and a boric acid washing liquid after impurities are removed, and this step is performed until the difference between the total content of metal impurities in the boric acid washing liquid and the total content of metal impurities in the boric acid solution is ≤30μg / L.

[0068] Since conventional activated carbon raw materials contain a large amount of impurities, especially a large amount of metal impurities, if the activated carbon raw materials are directly used for oil removal, more impurities will be introduced. The activated carbon obtained by the above impurity removal method has a low content of metal impurities. When deoiling the crude boric acid solution, it can not only achieve a good oil removal effect and significantly reduce the total organic carbon content, but also ensure that no new metal impurities are introduced into the purification system, which increases the difficulty of subsequent purification.

[0069] In the above impurity removal method, firstly, dilute sulfuric acid is used for thorough washing to soak out some acid-soluble metal impurities, then ultrapure water is used for washing to further remove impurities and wash away residual acid to avoid affecting subsequent steps, and finally, boric acid solution is used for washing. Since boric acid is relatively high in the activated carbon adsorption order, it can replace a large amount of metal impurities contained in the activated carbon raw material, so that the metal impurities are desorbed from the activated carbon, thereby achieving the effect of further purification of the activated carbon. The difference between the total content of metal impurities in the boric acid washing solution and the total content of metal impurities in the boric acid solution is ≤30μg / L, indicating that the impurities can basically no longer be desorbed from the activated carbon. The crude boric acid solution is deoiled using the activated carbon after impurities removal, and no new metal impurities are introduced into the purification system.

[0070] In some embodiments of the present invention, in the method for removing impurities from activated carbon, the concentration of dilute sulfuric acid is 0.1-1 mol / L; in some embodiments of the present invention, in the method for removing impurities from activated carbon, the concentration of dilute sulfuric acid is 0.3-0.7 mol / L.

[0071] In some embodiments of the present invention, in the method for removing impurities from activated carbon, the boric acid solution used can be the same as the crude boric acid solution in step S1, or a boric acid solution prepared with boric acid of higher purity can be used. It only needs to contain boric acid, and no specific requirements are made for its purity.

[0072] In the present invention, the degreasing step is first used to remove organic impurities in the crude boric acid solution, which can avoid the influence of organic impurities on the ion exchange step, so that the ion exchange agent can fully exchange ions with the metal impurities in the crude boric acid solution, thereby facilitating the removal of metal impurities in the subsequent steps. After the degreasing step of step S1, a boric acid degreasing solution with a low total organic carbon content can be obtained.

[0073] In some embodiments of the present invention, in step S1, the pH value of the crude boric acid solution during oil removal is 3.5-4.5; in some specific embodiments of the present invention, in step S1, the pH value of the crude boric acid solution during oil removal is 3.6-4.3; in some examples of the present invention, in step S1, the pH value of the crude boric acid solution during oil removal is 3.7-4.2; non-limiting specific examples are 3.8, 3.9, 4 or 4.1.

[0074] In some embodiments of the present invention, in step S1, the residence time of the crude boric acid solution in the activated carbon column during oil removal is 0.5 to 2 hours; in some specific embodiments of the present invention, in step S1, the residence time of the crude boric acid solution in the activated carbon column during oil removal is 0.6 to 1.8 hours; in some examples of the present invention, in step S1, the residence time of the crude boric acid solution in the activated carbon column during oil removal is 0.7 to 1.5 hours; non-limiting specific examples are 0.8 hours, 0.9 hours, 1 hour, 1.1 hours, 1.2 hours, 1.3 hours or 1.4 hours.

[0075] In some embodiments of the present invention, in step S1, the speed at which the crude boric acid solution passes through the activated carbon column during oil removal is 10 to 100 L / h; in some specific embodiments of the present invention, in step S1, the speed at which the crude boric acid solution passes through the activated carbon column during oil removal is 20 to 80 L / h; in some examples of the present invention, in step S1, the speed at which the crude boric acid solution passes through the activated carbon column during oil removal is 30 to 70 L / h; non-limiting specific examples are 35 L / h, 40 L / h, 45 L / h, 50 L / h, 55 L / h, 60 L / h or 65 L / h.

[0076] By controlling the residence time and passing speed of the crude boric acid solution in the activated carbon column during oil removal, a good TOC removal effect is ensured, which is also conducive to achieving a good metal impurity removal effect in the subsequent steps.

[0077] In some embodiments of the present invention, in step S1, the concentration of B in the boric acid degreasing solution is 2 to 20 g / L; in some specific embodiments of the present invention, in step S1, the concentration of B in the boric acid degreasing solution is 3 to 15 g / L; in some examples of the present invention, in step S1, the concentration of B in the boric acid degreasing solution is 5 to 10 g / L; non-limiting specific examples are 6 g / L, 7 g / L, 8 g / L or 9 g / L.

[0078] In some embodiments of the present invention, in step S1, the total organic carbon content in the boric acid degreasing liquid is ≤5 mg / L; in some specific embodiments of the present invention, in step S1, the total organic carbon content in the boric acid degreasing liquid is 1-5 mg / L; in some examples of the present invention, in step S1, the total organic carbon content in the boric acid degreasing liquid is 1-2 mg / L; non-limiting specific examples are 1.1, 1.2, 1.3 mg / L, 1.4 mg / L, 1.5 mg / L, 1.6 mg / L, 1.7 mg / L, 1.8 mg / L or 1.9 mg / L.

[0079] In some embodiments of the present invention, in step S1, the total content of metal impurities in the boric acid degreasing solution is ≥500 μg / L; in some specific embodiments of the present invention, in step S1, the total content of metal impurities in the boric acid degreasing solution is 500-1800 μg / L; in some examples of the present invention, in step S1, the total content of metal impurities in the boric acid degreasing solution is 550-1500 μg / L; non-limiting specific examples are 600 μg / L, 700 μg / L, 800 μg / L, 900 μg / L, 1000 μg / L, 1200 μg / L or 1400 μg / L.

[0080] In some embodiments of the present invention, in step S1, the boric acid degreasing solution includes the following components:

[0081] B 2~20g / L Total Organic Carbon (TOC) ≤5mg / L Metal impurities ≥500 μg / L

[0082] In some specific embodiments of the present invention, in step S1, the boric acid degreasing solution includes the following components:

[0083] B 2~20g / L Total Organic Carbon (TOC) 1~5mg / L Metal impurities 500~1800μg / L

[0084] In some examples of the present invention, in step S1, the boric acid degreasing solution includes the following components:

[0085]

[0086]

[0087] In some specific examples of the present invention, in step S1, the boric acid degreasing solution includes the following components:

[0088] B 2~20g / L Total Organic Carbon (TOC) 1~2mg / L Ca 200~400μg / L Cd 0.001~100μg / L Cr 0.1~100μg / L Fe 20~50μg / L Mg 40~200μg / L Mn 20~150μg / L Mo 0.001~50μg / L Na 20~50μg / L Ni 1~50μg / L Zn 10~50μg / L Al 30~55μg / L As 1~50μg / L Cu 0.01~50μg / L Pb 0.001~50μg / L K 15~50μg / L Au 0.001~50μg / L Ti 0.1~50μg / L In 0.001~50μg / L Sn 0.001~50μg / L Tl 0.001~50μg / L Hg 0.001~50μg / L

[0089] In some embodiments of the present invention, in step S2, the speed at which the boric acid degreasing liquid passes through the ion exchanger is 80 to 220 L / h; in some embodiments of the present invention, in step S2, the speed at which the boric acid degreasing liquid passes through the ion exchanger is 90 to 210 L / h; in some embodiments of the present invention, in step S2, the speed at which the boric acid degreasing liquid passes through the ion exchanger is 100 to 190 L / h; non-limiting specific examples are 120 L / h, 140 L / h, 160 L / h or 180 L / h.

[0090] By controlling the speed at which the boric acid degreasing liquid passes through the ion exchanger, sufficient ion exchange reaction is ensured between the ion exchanger and the metal impurities, and the metal impurities are adsorbed onto the ion exchanger to be removed from the solution, thereby achieving a good boric acid purification effect.

[0091] In some embodiments of the present invention, the ion exchanger is selected from a cation exchange resin; in some specific embodiments of the present invention, the cation exchange resin is selected from D001, LSC850, D860, D851, D401, D412 or 732.

[0092] Compared with anion exchange resin, the cation exchange resin used in the present invention can achieve better impurity removal effect and is more conducive to removing metal impurities in the system.

[0093] In some embodiments of the present invention, the particle size of the ion exchanger is 0.3-2 mm; in some specific embodiments of the present invention, the particle size of the ion exchanger is 0.5-1.8 mm; in some examples of the present invention, the particle size of the ion exchanger is 0.6-1.5 mm; non-limiting specific examples are 0.710-1.250 mm, 0.7 mm, 0.8 mm, 1 mm or 1.2 mm.

[0094] In some embodiments of the present invention, the exchange capacity of the ion exchanger is 10 to 30 mol / L; in some specific embodiments of the present invention, the exchange capacity of the ion exchanger is 12 to 28 mol / L; in some examples of the present invention, the exchange capacity of the ion exchanger is 15 to 25 mol / L; non-limiting specific examples are 18 mol / L, 2 mol / L or 22 mol / L.

[0095] Ion exchangers with specific particle size and exchange capacity are beneficial for better adsorption of metal impurities in the system, achieving better purification and impurity removal effects.

[0096] Through the ion exchange step of step S2, the metal impurities in the solution can be effectively removed to obtain an electronic grade boric acid solution with a low total content of metal impurities.

[0097] A second aspect of the embodiments of the present invention provides an electronic grade boric acid solution obtained by a purification method including the first aspect of the embodiments of the present invention.

[0098] The electronic grade boric acid solution obtained through the oil removal and ion exchange steps in the purification method of the present invention has the characteristics of low total content of metal impurities and low total organic carbon content, and has good application performance.

[0099] In some embodiments of the present invention, the concentration of B in the electronic grade boric acid solution is 2 to 20 g / L; in some specific embodiments of the present invention, the concentration of B in the electronic grade boric acid solution is 3 to 15 g / L; in some examples of the present invention, the concentration of B in the electronic grade boric acid solution is 5 to 10 g / L; non-limiting specific examples are 6 g / L, 7 g / L, 8 g / L or 9 g / L.

[0100] In some embodiments of the present invention, the total metal impurity content of the electronic grade boric acid solution is ≤100 μg / L; in some specific embodiments of the present invention, the total metal impurity content of the electronic grade boric acid solution is 20-100 μg / L; in some examples of the present invention, the total metal impurity content of the electronic grade boric acid solution is 30-80 μg / L; non-limiting specific examples are 40 μg / L, 50 μg / L, 60 μg / L or 70 μg / L.

[0101] The purification method of the present invention can effectively remove metal impurities in the solution, especially can remove a large amount of Ca element and more Fe, Mg, Mn, Na, Zn, Al, K elements contained in the original crude boric acid solution, and obtain an electronic grade boric acid solution with low content of Ca, Fe, Mg, Mn, Na, Zn, Al, K elements.

[0102] In some embodiments of the present invention, the Ca content in the electronic grade boric acid solution is ≤10 μg / L; in some specific embodiments of the present invention, the Ca content in the electronic grade boric acid solution is 1-10 μg / L; in some examples of the present invention, the Ca content in the electronic grade boric acid solution is 1.5-7 μg / L; non-limiting specific examples are 2 μg / L, 3 μg / L, 4 μg / L, 5 μg / L or 6 μg / L.

[0103] In some embodiments of the present invention, the Fe content in the electronic grade boric acid solution is ≤10 μg / L; in some specific embodiments of the present invention, the Fe content in the electronic grade boric acid solution is 0.001-10 μg / L; in some examples of the present invention, the Fe content in the electronic grade boric acid solution is 0.001-1 μg / L; non-limiting specific examples are 0.005 μg / L, 0.01 μg / L, 0.05 μg / L, 0.1 μg / L or 0.5 μg / L.

[0104] In some embodiments of the present invention, the Mg content in the electronic grade boric acid solution is ≤10 μg / L; in some specific embodiments of the present invention, the Mg content in the electronic grade boric acid solution is 1-10 μg / L; in some examples of the present invention, the Mg content in the electronic grade boric acid solution is 4-9 μg / L; non-limiting specific examples are 5 μg / L, 6 μg / L, 7 μg / L, or 8 μg / L.

[0105] In some embodiments of the present invention, the Mn element content in the electronic grade boric acid solution is ≤10 μg / L; in some specific embodiments of the present invention, the Mn element content in the electronic grade boric acid solution is 0.1-10 μg / L; in some examples of the present invention, the Mn element content in the electronic grade boric acid solution is 0.2-3 μg / L; non-limiting specific examples are 0.3 μg / L, 0.5 μg / L, 1 μg / L, 1.5 μg / L or 2 μg / L.

[0106] In some embodiments of the present invention, the Na content in the electronic grade boric acid solution is ≤45 μg / L; in some specific embodiments of the present invention, the Na content in the electronic grade boric acid solution is 20-45 μg / L; in some examples of the present invention, the Na content in the electronic grade boric acid solution is 25-40 μg / L; non-limiting specific examples are 28 μg / L, 30 μg / L, 32 μg / L, 35 μg / L or 38 μg / L.

[0107] In some embodiments of the present invention, the Zn element content in the electronic grade boric acid solution is ≤10 μg / L; in some specific embodiments of the present invention, the Zn element content in the electronic grade boric acid solution is 0.001-10 μg / L; in some examples of the present invention, the Zn element content in the electronic grade boric acid solution is 0.001-1 μg / L; non-limiting specific examples are 0.005 μg / L, 0.01 μg / L, 0.05 μg / L, 0.1 μg / L or 0.5 μg / L.

[0108] In some embodiments of the present invention, the Al element content in the electronic grade boric acid solution is ≤10 μg / L; in some specific embodiments of the present invention, the Al element content in the electronic grade boric acid solution is 0.001-10 μg / L; in some examples of the present invention, the Al element content in the electronic grade boric acid solution is 0.001-1 μg / L; non-limiting specific examples are 0.005 μg / L, 0.01 μg / L, 0.05 μg / L, 0.1 μg / L or 0.5 μg / L.

[0109] In some embodiments of the present invention, the K element content in the electronic grade boric acid solution is ≤10 μg / L; in some specific embodiments of the present invention, the K element content in the electronic grade boric acid solution is 3-10 μg / L; in some examples of the present invention, the K element content in the electronic grade boric acid solution is 5-8 μg / L; non-limiting specific examples are 5.5 μg / L, 6 μg / L, 6.5 μg / L, 7 μg / L or 7.5 μg / L.

[0110] In some embodiments of the present invention, the total organic carbon content of the electronic grade boric acid solution is ≤5 mg / L; in some specific embodiments of the present invention, the total organic carbon content of the electronic grade boric acid solution is 0.5-5 mg / L; in some examples of the present invention, the total organic carbon content of the electronic grade boric acid solution is 1-2 mg / L; non-limiting specific examples are 1.1, 1.2, 1.3 mg / L, 1.4 mg / L, 1.5 mg / L, 1.6 mg / L, 1.7 mg / L, 1.8 mg / L or 1.9 mg / L.

[0111] In some embodiments of the present invention, the electronic grade boric acid solution includes the following components:

[0112] B 2~20g / L Total Organic Carbon (TOC) ≤5mg / L Metal impurities ≤100 μg / L

[0113] In some specific embodiments of the present invention, the electronic grade boric acid solution includes the following components:

[0114] B 2~20g / L Total Organic Carbon (TOC) 0.5~5mg / L Metal impurities 20~100μg / L

[0115] In some examples of the present invention, the electronic grade boric acid solution includes the following contents:

[0116] B 2~20g / L Total Organic Carbon (TOC) 1~2mg / L Metal impurities 30~80μg / L

[0117] In some specific examples of the present invention, the electronic grade boric acid solution includes the following components:

[0118]

[0119]

[0120] In some embodiments of the present invention, the pH value of the electronic grade boric acid solution is 3.5-5; in some specific embodiments of the present invention, the pH value of the electronic grade boric acid solution is 3.8-4.5; in some embodiments of the present invention, the pH value of the electronic grade boric acid solution is 4-4.2; non-limiting specific examples are 4.05, 4.1 or 4.15.

[0121] A fourth aspect of the embodiments of the present invention provides an application of the electronic-grade boric acid solution of the second aspect of the embodiments of the present invention in the field of nano-scale chip integrated circuits.

[0122] The electronic-grade boric acid solution obtained by the purification method of the present invention has low total metal impurity content and low total organic carbon content, and thus has stable and good performance, and is widely used, especially in the field of nano-scale chip integrated circuits.

[0123] The content of the present invention is further described in detail below through specific examples. It should also be understood that the following examples are only used to further illustrate the present invention and cannot be construed as limiting the scope of protection of the present invention. Some non-essential improvements and adjustments made by those skilled in the art based on the principles set forth in the present invention all belong to the scope of protection of the present invention. The specific process parameters and the like in the following examples are also only examples within a suitable range, that is, those skilled in the art can make a selection within a suitable range through the description herein, and are not limited to the specific data exemplified below. The raw materials, reagents or devices used in the following examples and comparative examples, unless otherwise specified, can all be obtained from conventional commercial sources, or can be obtained by existing known methods.

[0124] In the following embodiments, ND means that when the content of a substance is lower than the minimum detection limit of the detection equipment, the substance will be marked as "ND" in the test report, indicating that the content of the substance is ≤0.01 μg / L.

[0125] In the following embodiments, metal impurities include Ca, Cd, Cr, Fe, Mg, Mn, Mo, Na, Ni, Zn, Al, As, Cu, Pb, K, Au, Ti, In, Sn, Tl and Hg elements, and the total content of metal impurities (total metal impurities) refers to the sum of the contents of the above metal impurities.

[0126] In the following embodiments, the water used in each step is ultrapure water, and the conductivity of the ultrapure water is less than 1 μS and the total content of metal impurities is less than 10 μg / L.

[0127] Example 1

[0128] A method for purifying electronic grade boric acid, the schematic diagram of the process is as follows Figure 1 As shown, the following steps are included:

[0129] S1. Preparation of crude solution: According to the mass ratio of crude boric acid to ultrapure water of 1:24.29, a crude boric acid solution with a B concentration of 7 g / L was prepared.

[0130] S2. Oil removal: The crude boric acid solution is passed through an activated carbon column for adsorption and oil removal to obtain a boric acid deoiled liquid. In this step, the pH value of the crude boric acid solution is 3.9, the residence time of the crude boric acid solution in the activated carbon column is 1 hour, the speed at which the crude boric acid solution passes through the activated carbon column is 50 L / h, and the column passing method is bottom-in and top-out.

[0131] In this step, before degreasing, the activated carbon column is prepared by the following steps: the activated carbon raw material is cleaned in three stages according to dilute sulfuric acid (0.5 mol / L)-ultrapure water-boric acid solution, specifically, soaked in dilute sulfuric acid (0.5 mol / L) for 20 to 30 hours; washed with ultrapure water until the conductivity of the washing liquid is ≤10 μS; washed with boric acid solution until the difference between the total content of metal impurities in the boric acid washing liquid and the total content of metal impurities in the boric acid solution is ≤30 μg / L, to obtain the activated carbon after impurity removal, which is filled into the column to obtain the activated carbon column for degreasing.

[0132] S3, ion exchange: at room temperature (25±5°C), the boric acid degreasing liquid is purified by a cation exchange resin column to obtain an electronic grade boric acid solution; in this step, the model of the cation exchange resin is D001, the resin particle size is 0.710-1.250 mm, and the exchange capacity is 20 mol / L; the column volume of the cation exchange resin column is 200 L, the effective volume is 175 L, the speed at which the boric acid degreasing liquid passes through the cation exchange resin column is 175 L / h, and the column passing method is top-in and bottom-out.

[0133] S4. Packaging: Put the electronic grade boric acid solution into the product packaging barrel.

[0134] The components and their contents in the solution system of each step in Example 1 were measured, and the results are shown in Table 1:

[0135] Table 1 Components and contents of the solution system in each step of Example 1

[0136]

[0137]

[0138] As can be seen from Table 1, in the purification method of Example 1 of the present invention, the crude boric acid solution contains a large amount of metal impurities and organic impurities, and the total content of metal impurities reaches 657.71 μg / L, wherein the Ca content is above 300 μg / L, the Mg and Al contents are both above 50 μg / L, and the TOC content reaches 10.57 mg / L; through the deoiling step, the organic impurities in the solution can be effectively removed, so that the TOC content in the obtained boric acid deoiling solution is greatly reduced; through the ion exchange step, the metal impurities in the solution can be effectively removed, so that the total content of metal impurities in the obtained boric acid purified solution is greatly reduced. The pH value of the electronic grade boric acid solution in this example is 4.1.

[0139] In addition, the ion exchange in this example is carried out at room temperature (25±5°C). If the temperature is too high, the exchange groups in the resin may be damaged, thereby reducing the exchange capacity of the resin; if the temperature is too low, the activity of the exchange groups of the resin will decrease, causing the exchange process to become slow and reducing the purification effect.

[0140] Example 2

[0141] A method for purifying electronic grade boric acid is different from Example 1 in that, in step S3 of this example, the ion exchange resin is replaced by an anion exchange resin with model D301 and a particle size of 0.315 to 1.25 mm, and the other steps are the same as Example 1.

[0142] The total content of metal impurities in the electronic grade boric acid solution obtained by ion exchange in different ion exchange resins was detected to characterize the effect of the ion exchange resin on the impurity removal effect of the ion exchange step. The results are shown in Table 2.

[0143] Table 2 Effect of ion exchange resin on the impurity removal effect of ion exchange step

[0144] Resin Type D301 anion exchange resin D001 cation exchange resin Resin particle size (mm) 0.315～1.25 0.710-1.250 Total gold impurities in boric acid degreasing liquid (μg / L) 640.61 640.61 Total gold impurities in electronic grade boric acid solution (μg / L) 437.91 49.28 Total metal impurities removal rate (%) 31.62 92.30

[0145] As can be seen from Table 2, the type of ion exchange resin has a great influence on the impurity removal effect. Compared with anion exchange resin, cation exchange resin has a better effect on removing metal impurities from boric acid degreasing liquid.

[0146] Example 3

[0147] A method for purifying electronic grade boric acid, which differs from Example 1 in that, in step S3 of this example, the speed (column passing speed) of the boric acid deoiling liquid passing through the cation exchange resin column is changed, and the specific column passing speed is shown in Table 3, and the other steps are the same as Example 1.

[0148] The total content of metal impurities in the electronic grade boric acid solution obtained at different column flow rates was detected to characterize the effect of the column flow rate on the impurity removal effect of the ion exchange step. The results are shown in Table 3.

[0149] Table 3 Effect of column speed on impurity removal effect of ion exchange step

[0150] Column speed (L / h) 100 125 150 175 190 Total gold impurities in boric acid degreasing liquid (μg / L) 640.61 640.61 640.61 640.61 640.61 Total gold impurities in electronic grade boric acid solution (μg / L) 46.28 47.30 48.52 49.28 68.79 Total metal impurities removal rate (%) 92.77 92.61 92.42 92.30 89.26

[0151] As can be seen from Table 3, the column speed affects the impurity removal effect of the ion exchange step. The column speed within the range of the embodiment of the present invention (such as 100-190 L / h) has a good impurity removal effect. If the column speed is too fast, the impurity removal effect is poor. By adopting an appropriate column speed, an electronic grade boric acid solution with a low total content of metal impurities can be obtained.

[0152] In summary, the purification method of the present invention is simple and efficient. Through the steps of oil removal and ion exchange, impurities in the crude boric acid solution can be effectively removed to obtain an electronic grade boric acid solution with low total metal impurity content and low total organic carbon content. The electronic grade boric acid solution has stable and good performance, and is widely used, especially in the field of nano-chip integrated circuits.

Claims

1. A method for purifying electronic grade boric acid, characterized in that: The following steps are involved: S1. Deoiling: Deoiling the crude boric acid solution through an adsorbent to obtain a boric acid deoiled solution; S2. Ion exchange: purifying the boric acid degreasing liquid through an ion exchanger to obtain an electronic grade boric acid solution.

2. The purification method according to claim 1, characterized in that In step S1, the concentration B of the crude boric acid solution is 2 to 20 g / L.

3. The purification method according to claim 1, characterized in that In step S1, the crude boric acid solution contains metal impurities and / or organic impurities.

4. The purification method according to claim 3, characterized in that In step S1, the metal impurities in the crude boric acid solution include at least one element of Ca, Cd, Cr, Fe, Mg, Mn, Mo, Na, Ni, Zn, Al, As, Cu, Pb, K, Au, Ti, In, Sn, Tl or Hg.

5. The purification method according to claim 3, characterized in that: In step S1, the total content of metal impurities in the crude boric acid solution is ≥500 μg / L; And / or, the total organic carbon content in the crude boric acid solution is ≥8 mg / L.

6. The purification method according to claim 1, characterized in that: In step S1, the adsorbent is activated carbon; Preferably, the activated carbon is obtained by an impurity removal method comprising the following steps: primary cleaning: using dilute sulfuric acid to clean the activated carbon raw material and soaking it for 20 to 30 hours to obtain primary activated carbon; secondary cleaning: using ultrapure water to clean the primary activated carbon to obtain secondary activated carbon and a water washing liquid, and this step is performed until the conductivity of the water washing liquid is ≤10μS; tertiary cleaning: using a boric acid solution to clean the secondary activated carbon to obtain activated carbon and a boric acid washing liquid after impurities are removed, and this step is performed until the difference between the total content of metal impurities in the boric acid washing liquid and the total content of metal impurities in the boric acid solution is ≤30μg / L.

7. The purification method according to claim 1, characterized in that: In step S2, the boric acid degreasing liquid passes through the ion exchanger at a rate of 80 to 220 L / h; and / or, the ion exchanger is selected from cation exchange resins; and / or, the particle size of the ion exchanger is 0.3 to 2 mm; And / or, the exchange capacity of the ion exchanger is 10 to 30 mol / L.

8. An electronic grade boric acid solution, characterized in that: The product is obtained by the purification method described in any one of claims 1 to 7.

9. The electronic grade boric acid solution according to claim 8, characterized in that The concentration of B in the electronic grade boric acid solution is 2 to 20 g / L; And / or, the total metal impurity content of the electronic grade boric acid solution is ≤100 μg / L; And / or, the total organic carbon content of the electronic grade boric acid solution is ≤5 mg / L; And / or, the pH value of the electronic grade boric acid solution is 3.5-5.

10. Use of the electronic grade boric acid solution according to claim 8 or 9 in the field of nano-scale chip integrated circuits.

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