A multi-stage membrane separation and ion adsorption method for removing impurities from electronic-grade ammonia water

Abstract

This invention discloses a multi-stage membrane separation and ion adsorption method for removing impurities from electronic-grade ammonia water, belonging to the field of electronic chemical purification. The method includes vaporizing raw liquid ammonia to obtain an ammonia-containing main gas stream, and regulating the flow and controlling entrained droplets of the ammonia-containing main gas stream. The ammonia-containing main gas stream is then introduced into a pre-absorption boron selective depletion section, which includes a high-purity inert porous support and a confined micro-hydration selective interface constructed on the surface of the high-purity inert porous support. By setting the pre-absorption boron selective depletion section after liquid ammonia vaporization and before ultrapure water absorption, and utilizing immobilized boron recognition sites on the confined micro-hydration selective interface to locally transform and selectively bind boron-containing impurities, the boron-containing impurities are directionally retained before entering the liquid-phase absorption system, thus solving the problem of inefficient removal of boron-containing impurities after entering the absorbent in existing technologies.

Description

Technical Field

[0001] This invention relates to the field of electronic chemical purification technology, and more specifically, to a multi-stage membrane separation and ion adsorption method for removing impurities from electronic-grade ammonia. Background Technology

[0002] Electronic-grade ammonia is widely used in cleaning, etching, and surface treatment processes in the manufacturing of semiconductors, integrated circuits, flat panel displays, and precision electronic devices. With the continuous reduction in device linewidth and the increasing demands for process cleanliness, trace impurities in electronic-grade ammonia, especially boron, metal ion, particulate, and colloidal impurities, can adversely affect wafer surface condition, thin film quality, and device yield. Therefore, the stable preparation of low-boron, low-metal, and low-particulate electronic-grade ammonia has become a crucial technical challenge in the field of electronic chemical purification.

[0003] Existing methods for preparing electronic-grade ammonia typically employ a process route involving liquid ammonia vaporization, washing and purification, ultrapure water absorption, membrane filtration, and resin polishing to reduce impurity content and improve product purity. Multi-stage membrane separation removes particulate impurities, colloidal impurities, and some micro-clusters, while ion adsorption units further remove residual metal ions and anionic impurities. However, most existing technologies involve subsequent purification of impurities in the liquid phase system after ammonia absorption to form liquid ammonia. For boron-containing impurities, after liquid ammonia vaporization, they may enter the subsequent absorption stage as volatile boron-containing impurities or in a state of coordination or association with ammonia. Once in the absorbent, they are often more difficult to remove efficiently through conventional filtration or simple separation methods. This leads to a concentration of boron removal load on the terminal resin or polishing unit, increasing operational burden, potentially causing increased ammonia loss, decreased process stability, and higher continuous operating costs. Summary of the Invention

[0004] To address the problems mentioned in the background section, the present invention provides the following technical solution: A multi-stage membrane separation and ion adsorption method for removing impurities from electronic-grade ammonia water includes the following steps: S1. The raw material liquid ammonia is vaporized to obtain an ammonia-containing main gas flow, and the ammonia-containing main gas flow is stabilized and the entrained droplets are controlled. S2. The ammonia-containing main gas flow is introduced into the pre-absorption boron selective depletion section. The pre-absorption boron selective depletion section includes a high-purity inert porous support and a confined microhydration selective interface constructed on the surface of the high-purity inert porous support. The confined microhydration selective interface is provided with immobilized boron recognition sites. S3. Control the local water activity of the confined micro-hydration selective interface to be lower than that of the subsequent ultrapure water absorption section, so that the boron-containing volatile impurities or boron-containing impurities that form coordination or association relationships with ammonia in the ammonia-containing main gas flow preferentially enter the confined micro-hydration selective interface, and form local transformation species under the action of the immobilized boron recognition sites, so as to directionally intercept the boron-containing volatile impurities or boron-containing impurities that form coordination or association relationships with ammonia, while inhibiting the large-scale absorption of ammonia in the boron selective depletion section before absorption; S4. The ammonia-containing main gas flow after being treated by the boron selection depletion section before absorption is introduced into the ultrapure water absorption section for absorption to obtain primary electronic grade ammonia water. S5. The primary electronic grade ammonia water is introduced into a multi-stage membrane separation section, and particulate impurities, colloidal impurities, micro-cluster impurities and residual separable associative compounds are removed in stages by at least two membrane separation units. S6. The electronic-grade ammonia water processed by the multi-stage membrane separation section is introduced into the ion adsorption polishing section to adsorb and remove residual trace metal ions and anionic impurities, thereby obtaining the electronic-grade ammonia water product. Furthermore, the immobilized boron recognition site includes a weakly basic modulating group and an ortho-hydroxyl recognition group disposed on the confined microhydration selective interface. The weakly basic modulating group is used to promote the formation of the locally transformed species by the boron-containing volatile impurities or boron-containing impurities that form coordination or association relationships with ammonia. The ortho-hydroxyl recognition group is used to selectively bind to the locally transformed species.

[0005] Furthermore, the weakly basic modulating group and the ortho-hydroxyl recognition group are sequentially arranged along the flow direction of the ammonia-containing main gas flow, so that the boron-containing volatile impurities or boron-containing impurities that form a coordination relationship or association relationship with ammonia first form the locally transformed species, and then are selectively bound by the ortho-hydroxyl recognition group.

[0006] Furthermore, the confined micro-hydration selection interface introduces ultrapure water into the interior of the high-purity inert porous carrier through a micro-water supply channel located on the side of the high-purity inert porous carrier away from the ammonia-containing main gas flow, so that the ultrapure water forms a micro-wetting layer on the side of the high-purity inert porous carrier in contact with the ammonia-containing main gas flow under capillary migration.

[0007] Furthermore, the water supply rate of the micro-water supply channel is adjusted in conjunction with the flow rate of the ammonia-containing main gas flow to keep the micro-wetting layer continuous and prevent free droplets from falling off, and to make the local water activity of the confined micro-hydration selective interface lower than the water activity of the ultrapure water absorption section.

[0008] Furthermore, along the flow direction of the ammonia-containing main gas flow, the confined micro-hydration selective interface includes an upstream region and a downstream region. In the upstream region, the distribution density of the weakly basic modulating group is greater than the distribution density of the ortho-hydroxyl recognition group, and in the downstream region, the distribution density of the ortho-hydroxyl recognition group is greater than the distribution density of the weakly basic modulating group.

[0009] Furthermore, the outlet of the pre-absorption boron selective depletion section is directly connected to the inlet of the ultrapure water absorption section through a sealed conveying channel, so that the ammonia-containing main gas flow after being treated by the pre-absorption boron selective depletion section enters the ultrapure water absorption section without intermediate storage.

[0010] In summary, the present invention has the following beneficial effects: By setting a boron selective depletion section before absorption and after liquid ammonia vaporization and before ultrapure water absorption, and by using immobilized boron recognition sites at the confined micro-hydration selective interface to locally transform and selectively bind boron-containing impurities, boron-containing impurities are directionally intercepted before entering the liquid phase absorption system, thus solving the problem of efficient removal of boron-containing impurities after entering the absorbent in the prior art. Detailed Implementation

[0011] Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0012] Example 1 This invention provides a technical solution: a multi-stage membrane separation and ion adsorption method for removing impurities from electronic-grade ammonia water, comprising the following steps: S1. The raw material liquid ammonia is vaporized to obtain an ammonia-containing main gas flow, and the flow of the ammonia-containing main gas flow is stabilized and the entrained droplets are controlled. S2. The ammonia-containing main gas flow is introduced into the pre-absorption boron selective depletion section. The pre-absorption boron selective depletion section includes a high-purity inert porous support and a confined microhydration selective interface constructed on the surface of the high-purity inert porous support. Immobilized boron recognition sites are set on the confined microhydration selective interface. S3. The local water activity of the confined microhydration selective interface is lower than that of the subsequent ultrapure water absorption section, so that the boron-containing volatile impurities or boron-containing impurities that form coordination or association relationships with ammonia in the ammonia-containing main gas flow preferentially enter the confined microhydration selective interface and form local transformation species under the action of immobilized boron recognition sites, so as to directionally retain the boron-containing volatile impurities or boron-containing impurities that form coordination or association relationships with ammonia, while inhibiting the large-scale absorption of ammonia in the boron selective depletion section before absorption; S4. The ammonia-containing main gas flow after being treated by the boron selection depletion section before absorption is introduced into the ultrapure water absorption section for absorption to obtain primary electronic grade ammonia water. S5. Primary electronic-grade ammonia water is introduced into the multi-stage membrane separation section, and particulate impurities, colloidal impurities, micro-cluster impurities and residual separable associative compounds are removed by at least two stages of membrane separation units. S6. Electronic-grade ammonia water after being processed by the multi-stage membrane separation section is introduced into the ion adsorption polishing section to adsorb and remove residual trace metal ions and anionic impurities, thereby obtaining electronic-grade ammonia water product. In this embodiment, electronic-grade liquid ammonia with a purity of 99.995 wt% was used as the raw material. To examine the removal capability of this embodiment for boron-containing impurities, trimethylborate standard solution was added to the liquid ammonia using a micro-metering method while retaining the background impurity profile of the raw liquid ammonia, so that the total boron content entering the vaporization section was controlled within the range of 60 ± 3 μg / kg. Testing revealed that the background sodium content in the liquid ammonia before entering the experimental system was 7 μg / kg to 10 μg / kg, the iron content was 3 μg / kg to 5 μg / kg, and the chloride ion content was 12 μg / kg to 16 μg / kg.

[0013] First, the raw material, liquid ammonia, is fed into a vaporizer for vaporization. The ammonia flow rate is controlled at 2.20 kg / h, the vaporization temperature at 35℃ to 37℃, and the vaporization pressure at 0.22 MPa to 0.25 MPa. After vaporization, an ammonia-containing main gas stream is obtained. This main gas stream first enters a flow stabilizer, and then passes through a PFA wire mesh demister to control entrained droplets. After treatment, the flow rate of the ammonia-containing main gas stream is stabilized at 2.82 Nm³. 3 / h to 2.90Nm 3 The rate of entrained droplets at the outlet is controlled between [amount] and [amount] / h, with the amount controlled at 0.8 mg / Nm³. 3 the following.

[0014] The ammonia-containing main gas flow is then introduced into the pre-absorption boron selective depletion section. The pre-absorption boron selective depletion section comprises a high-purity inert porous support and a confined micro-hydration selective interface constructed on the surface of the high-purity inert porous support. In this embodiment, the high-purity inert porous support is a high-purity porous alumina plate with an alumina purity of 99.99 wt%, a single plate size of 250 mm × 150 mm × 2 mm, an average pore size of 1.1 μm, a porosity of 40%, and a total gas contact area of ​​0.18 m². 2 To reduce potential metal contamination from the carrier itself, the high-purity inert porous carrier was subjected to sequential rinsing with 18.2 MΩ·cm ultrapure water, hot air drying at 80℃, and desorption treatment at 120℃ before functionalization.

[0015] A confined microhydration selective interface was constructed on the side of a high-purity inert porous support in contact with the ammonia-containing main gas flow. Immobilized boron recognition sites were set on this interface, including a weakly basic modulating group and an ortho-hydroxyl recognition group. Specifically, imidazole-type weakly basic modulating groups were first grafted onto the surface of the high-purity inert porous support, with a basic grafting density controlled at 0.42 μmol / cm². 2 Up to 0.55 μmol / cm 2 Furthermore, imidazole-type weakly basic modulators are added to the first 35% of the region along the main ammonia-containing gas flow direction to increase the total grafting density in this region to 1.18 μmol / cm². 2 Up to 1.27 μmol / cm 2 Finally, in the last 65% region, ortho-hydroxyl recognition groups formed by the reaction of epoxy silane and N-methyl-D-glucosamine were grafted, with their surface density controlled at 1.58 μmol / cm². 2 Up to 1.72 μmol / cm 2 This results in a distribution structure of immobilized boron recognition sites that are biased towards upstream modulation and downstream recognition along the main ammonia-containing gas flow direction.

[0016] A micro-water supply channel is set on the side of the high-purity inert porous carrier away from the main ammonia-containing gas flow. Ultrapure water is introduced into the high-purity inert porous carrier through the micro-water supply channel, and the water supply rate is controlled at 0.88 mL / min.

[0017] Ultrapure water reaches the surface of a high-purity inert porous support through capillary migration and forms a continuously distributed micro-wetting layer in the region where the immobilized boron recognition sites are located. In the experiment, the absence of visible droplets at the outlet, the absence of condensate accumulation, and stable pressure drop were used as the criteria to ensure that the local water activity at the confined micro-hydration selective interface was lower than that in the subsequent ultrapure water absorption section.

[0018] Under these conditions, boron-containing volatile impurities in the ammonia-containing main gas stream, or boron-containing impurities that coordinate or associate with ammonia, preferentially enter the confined micro-hydration selective interface. Under the influence of weakly basic modulating groups, they form locally transformed species. Subsequently, ortho-position polyhydroxyl recognition groups selectively bind to these locally transformed species, thus achieving targeted retention of boron-containing impurities before they enter the subsequent ultrapure water absorption section. The residence time in the boron selective depletion section before absorption is controlled at 0.41 s, and the operating pressure drop is controlled at approximately 2.2 kPa.

[0019] The ammonia-containing main gas stream, after being treated in the boron selection depletion section before absorption, is directly introduced into the ultrapure water absorption section without intermediate storage. The ultrapure water absorption section adopts a two-stage countercurrent absorption method. The resistivity of the absorption water is 18.2 MΩ·cm, the absorption liquid temperature is controlled at 12℃ to 14℃, and the total water supply is controlled between 5.25 L / h and 5.40 L / h. After absorption, primary electronic-grade ammonia water is obtained, with an ammonia concentration maintained at approximately 28 wt%.

[0020] Primary electronic-grade ammonia solution is introduced into a multi-stage membrane separation section, which comprises two membrane separation units. The first membrane separation unit uses a high-purity alumina microfiltration membrane with a pore size of 0.10 μm to remove particulate impurities and large-particle colloids. The second membrane separation unit uses a zirconia ultrafiltration membrane with a particle size cutoff of 20 nm to further remove micro-cluster impurities and residual separable associative compounds. Both membrane separation units operate in a cross-flow mode, with the operating temperature maintained between 20°C and 22°C.

[0021] The electronic-grade ammonia solution, after being processed by a multi-stage membrane separation section, is introduced into an ion adsorption polishing section. The ion adsorption polishing section includes a low-precipitation chelating resin column and a low-precipitation anion resin column arranged sequentially. The low-precipitation chelating resin column is used to remove residual trace metal ions, and the low-precipitation anion resin column is used to remove residual anion impurities. The empty bed linear velocity of the resin columns is controlled at 3 BV / h. After the above treatment, the electronic-grade ammonia solution product is obtained.

[0022] To verify the supporting effect of this embodiment, three comparative examples were set up.

[0023] In Comparative Example 1, the boron depletion section before absorption was removed, and the vaporized ammonia-containing main gas flow directly entered the ultrapure water absorption section. The subsequent multi-stage membrane separation section and ion adsorption polishing section remained the same as in this embodiment.

[0024] In Comparative Example 2, the high-purity inert porous carrier and micro-water supply channel are retained, but the immobilized boron recognition sites are removed, and only a normal micro-wetting interface is formed. The subsequent process is consistent with that of this embodiment.

[0025] In Comparative Example 3, the immobilized boron recognition sites were retained, but the back-side water supply rate was increased to 3.20 mL / min, causing local free droplets to form on the gas contact surface. The subsequent process was consistent with that of this embodiment.

[0026] The main operating conditions for each group of experiments are shown in Table 1: Table 1: Main operating conditions for each group of experiments

[0027] For sample testing, boron, sodium, and iron were detected using ICP-MS; chloride ions were detected using ion chromatography; ammonia concentration was detected using acid-base titration; the number of particles larger than 50 nm was detected using a liquid particle counter; and TOC was detected using a high-temperature catalytic oxidation method. Each group ran continuously for 8 hours. After reaching a steady state after 2 hours of operation, samples were taken at the 3rd, 5th, and 7th hours. The data in Tables 2 and 3 are the average values ​​of the three samplings.

[0028] The results of each group in the pre-absorption treatment and primary absorption stage are shown in Table 2: Table 2: Results of each group in pre-absorption treatment and primary absorption stage

[0029] As shown in Table 2, after setting a boron selection depletion section before absorption in this embodiment, the boron content in the primary electronic grade ammonia water decreased from 8.37 μg / L in Comparative Example 1 to 0.94 μg / L, indicating that boron impurities were significantly reduced before entering the ultrapure water absorption section.

[0030] Comparative Example 2 shows that relying solely on ordinary trace wetting interfaces has a certain reduction effect on boron-containing impurities, but its effect is significantly lower than that of this embodiment with immobilized boron recognition sites. This indicates that the selective binding of immobilized boron recognition sites to locally transformed species is necessary for achieving targeted retention before absorption.

[0031] Comparative Example 3 shows that although increasing the back-side water supply rate can further reduce the boron content in the primary electronic grade ammonia water, it will significantly increase ammonia loss and lead to increased pressure drop and free droplet shedding. This indicates that in this embodiment, the confined micro-hydration selective interface should maintain a micro-wetting state and should not be transformed into a normal pre-absorption state.

[0032] The quality inspection results of the final products of each group are shown in Table 3: Table 3: Final Product Quality Inspection Results for Each Group

[0033] As shown in Table 3, with the subsequent multi-stage membrane separation section and ion adsorption polishing section being identical, the differences in sodium, iron, chloride ions, and particle number in the final products of each group were not significant, while the boron content differed significantly. Specifically, the boron content in the final product of this embodiment was 0.26 μg / L, significantly lower than 2.93 μg / L in Comparative Example 1 and 1.27 μg / L in Comparative Example 2. This indicates that the key function of this embodiment does not lie in the subsequent multi-stage membrane separation section or ion adsorption polishing section, but rather in the directional retention of boron before it enters the liquid phase system through the pre-absorption boron selective depletion section, thereby reducing the probability of the formation of difficult-to-remove boron-containing forms in the subsequent liquid phase. Although Comparative Example 3 further reduced the boron content in the final product, its ammonia concentration decreased more significantly, and its TOC increased. This indicates that when the micro-water supply is too high, the system deviates from the confined micro-hydration interface state, increasing ammonia loss and improving operational instability.

[0034] To further verify the continuous operation capability of this embodiment, the system was run continuously for 24 hours, with samples taken every 4 hours. The test results are shown in Table 4. Table 4: Continuous Operation Stability Results of Example 1

[0035] As shown in Table 4, during the 24-hour continuous operation, the boron content and pressure drop in the final product showed only a slow upward trend with relatively small overall fluctuations. This indicates that the boron selective depletion section before absorption has good continuous operation stability and can meet the continuous operation requirements in the preparation process of electronic-grade ammonia.

[0036] In summary, this embodiment sets up a boron selective depletion section before absorption after liquid ammonia vaporization and before ultrapure water absorption. By utilizing the synergistic effect between a high-purity inert porous carrier, a confined micro-hydration selective interface, and immobilized boron recognition sites, boron-containing volatile impurities or boron-containing impurities that form coordination or association relationships with ammonia are directionally retained before entering the ultrapure water absorption section. Combined with subsequent multi-stage membrane separation sections and ion adsorption polishing sections, a low-boron, low-particle, and low-metal-ion electronic-grade ammonia water product is finally obtained.

[0037] Example 2 The immobilized boron recognition site includes a weakly basic modulating group and an ortho-hydroxyl recognition group disposed on the confined microhydration selective interface. The weakly basic modulating group is used to promote the formation of locally transformed species from boron-containing volatile impurities or boron-containing impurities that form coordination or association relationships with ammonia. The ortho-hydroxyl recognition group is used to selectively bind to the locally transformed species. The weakly basic modulating group and the ortho-position polyhydroxy recognition group are sequentially arranged along the flow direction of the ammonia-containing main gas flow, so that the boron-containing volatile impurities or boron-containing impurities that form coordination or association relationships with ammonia first form locally transformed species, and then are selectively bound by the ortho-position polyhydroxy recognition group. The confined micro-hydration selective interface introduces ultrapure water into the interior of the high-purity inert porous carrier through a micro-water supply channel located on the side of the high-purity inert porous carrier away from the main ammonia-containing gas flow. Under capillary migration, the ultrapure water forms a micro-wetting layer on the side of the high-purity inert porous carrier that is in contact with the main ammonia-containing gas flow.

[0038] In this embodiment: This embodiment is based on the overall process route of Example 1. The operating conditions of liquid ammonia vaporization, ammonia-containing main gas flow rate, subsequent ultrapure water absorption section, multi-stage membrane separation section, and ion adsorption polishing section are consistent with those of Example 1, and will not be repeated here. This embodiment focuses on illustrating the interface preparation process of the boron selective depletion section before absorption and its impact on the directional retention of boron-containing impurities.

[0039] The high-purity inert porous carrier used in this embodiment is a high-purity porous alumina plate with an alumina purity of 99.99 wt%, dimensions of 250 mm × 150 mm × 2 mm, an average pore size of 1.1 μm, and a porosity of 40%. Before surface functionalization, the high-purity porous alumina plate was first ultrasonically cleaned in 18.2 MΩ·cm ultrapure water for 15 min, then hot-air dried at 80°C for 30 min, and subsequently desorbed at 120°C for 2 h to remove adsorbed water and organic residues from the surface. After cooling to room temperature, the treated high-purity porous alumina plate was immediately transferred to a cleanroom environment for subsequent grafting operations.

[0040] First, a weakly basic modulating group was constructed. Pretreated high-purity porous alumina plates were placed in a mixed solution of anhydrous ethanol and deionized water. 3-chloropropyltrimethoxysilane was added to the solution, with the silane concentration controlled at 1.8 wt%. The reaction temperature was 45℃, and the reaction time was 2 h to form a chloropropyl active layer on the support surface. After the reaction, the plates were rinsed three times with anhydrous ethanol and then dried at 70℃ for 30 min. Subsequently, the porous alumina plates with the chloropropyl active layer were immersed in an imidazole ethanol solution and reacted at 60℃ for 4 h to fix the imidazole groups on the surface of the high-purity inert porous support, forming a weakly basic modulating group. Surface elemental analysis and grafting amount determination showed that the overall basic grafting density was controlled at 0.46 μmol / cm². 2 Up to 0.53 μmol / cm 2 .

[0041] Based on this, along the flow direction of the subsequent ammonia-containing main gas flow, the first 35% region of the high-purity inert porous support was designated as the upstream modulation enhancement zone. In this region, a secondary grafting treatment with imidazole groups was performed. For the secondary grafting, a 0.9 wt% imidazole precursor solution was used, the reaction temperature was 50℃, and the reaction time was 1.5 h, increasing the total grafting density of weakly basic modulation groups in the upstream modulation enhancement zone to 1.20 μmol / cm³. 2 Up to 1.26 μmol / cm2 After grafting, the static water contact angle of the upstream modulated enhancement zone decreased from 62° on the original carrier to 41° to 45°, indicating that the surface wettability of this region is enhanced, which is beneficial to the stable spreading of the subsequent micro-wetting layer.

[0042] Subsequently, ortho-hydroxyl recognition groups were constructed. The last 65% of a high-purity inert porous support along the gas flow direction was designated as the downstream recognition enhancement region. This region was first epoxidized with γ-glycidoxypropyltrimethoxysilane at 50°C for 2.5 h. After washing, it was reacted with an aqueous solution of N-methyl-D-glucosamine at 65°C for 5 h to immobilize the ortho-hydroxyl structure from N-methyl-D-glucosamine onto the surface of the high-purity inert porous support, forming ortho-hydroxyl recognition groups. The grafting density of the ortho-hydroxyl recognition groups in the downstream recognition enhancement region was controlled at 1.61 μmol / cm², as determined by surface grafting amount measurement. 2 Up to 1.69 μmol / cm 2 To avoid abrupt boundary formation between the upstream modulation enhancement region and the downstream recognition enhancement region, a transition region with a length of 15 mm is set at the junction of the two regions. Within this transition region, the density of weakly basic modulation groups gradually decreases while the density of ortho-position polyhydroxy recognition groups gradually increases, thereby reducing local mass transfer disturbances during interface switching.

[0043] After the above treatment, immobilized boron recognition sites are formed on the surface of the high-purity inert porous support. These immobilized boron recognition sites consist of weakly basic modulating groups and ortho-hydroxyl recognition groups, arranged sequentially along the flow direction of the ammonia-containing main gas stream. Specifically, the distribution density of weakly basic modulating groups is higher in the upstream region than in the ortho-hydroxyl recognition groups, while the distribution density of ortho-hydroxyl recognition groups is higher in the downstream region than in the weakly basic modulating groups. This arrangement allows boron-containing volatile impurities, or boron-containing impurities that coordinate or associate with ammonia, to be preferentially modulated by the local weakly basic environment when passing through the upstream region, forming more easily identifiable locally transformed species. As they continue to migrate downstream, they are selectively bound by the ortho-hydroxyl recognition groups, thus achieving a continuous process of modulation followed by recognition.

[0044] To create a confined micro-hydration selective interface, a micro-water supply channel was fabricated on the side of the high-purity inert porous carrier away from the main ammonia-containing gas flow. The micro-water supply channel employs a parallel microgroove structure with a width of 0.40 mm and a depth of 0.35 mm, with a center-to-center spacing of 3.0 mm between adjacent microgrooves, totaling 48 microgrooves. The micro-water supply channel is connected to an ultrapure water storage unit, with the supply end pressure controlled between 6 kPa and 8 kPa. During operation, 18.2 MΩ·cm ultrapure water is introduced into the micro-water supply channel at a flow rate of 0.82 mL / min to 0.95 mL / min, allowing the ultrapure water to migrate capillarily into the interior of the high-purity inert porous carrier and form a continuously distributed micro-wetting layer on the gas-contact surface. The steady-state water holding capacity of the gas-contact surface was measured to be 1.9 mg / cm³ by weighing. 2 Up to 2.3 mg / cm 2 In this state, no visible free droplets were observed on the surface, and no significant droplet shedding was observed after 6 hours of continuous operation. This indicates that the formed liquid layer is in a confined distribution state, rather than a typical pre-absorbed liquid film.

[0045] After the interface was constructed as described above, it was assembled into the boron selective depletion section before absorption and subjected to continuous operation tests under the same feed conditions as in Example 1. Three comparison groups were set up. In comparison group A, only ortho-position polyhydroxy recognition groups were grafted, and no weakly basic modulating groups were set, while the other conditions remained the same. In comparison group B, both weakly basic modulating groups and ortho-position polyhydroxy recognition groups were set, but the two types of groups were uniformly mixed and distributed, without forming an upstream modulating enhancement zone and a downstream recognition enhancement zone. In comparison group C, the upstream and downstream partitions were retained, but the back-side micro-water supply channel was removed, and an unstable hydration layer was formed on the surface only through air pre-humidification. The interface construction and operation results of Example 2 and the comparison groups are shown in Table 5.

[0046] Table 5: Interface construction and running results of Example 2 and the comparison group

[0047] As shown in Table 5, in Comparative Group A, which only had an ortho-hydroxyl recognition group but no weakly basic modulating group, the boron content in the primary electronic grade ammonia water was 2.47 μg / L, significantly higher than the 0.91 μg / L in Example 2. This indicates that although the ortho-hydroxyl recognition group has a certain recognition ability, its interface capture efficiency for boron-containing impurities is significantly insufficient in the absence of a weakly basic modulating group to induce local morphological transformation. In Comparative Group B, the weakly basic modulating group and the ortho-hydroxyl recognition group were uniformly mixed and distributed, and the boron content in the primary electronic grade ammonia water was 1.58 μg / L. This indicates that even if both types of groups are present simultaneously, if a progressive structure of modulation followed by recognition is not formed along the airflow direction, its reduction effect on boron-containing impurities is still significantly lower than that of Example 2. In comparison group C, after the backside micro-water supply channel was removed, the steady-state water holding capacity at the interface fluctuated significantly, the pressure drop increased, and the boron content in the primary electronic grade ammonia water rebounded to 1.94 μg / L. This indicates that the stable formation of the confined micro-hydration selective interface has an important impact on the continued function of the immobilized boron recognition sites.

[0048] The surface state of the immobilized boron recognition sites in Example 2 was further characterized. XPS testing showed that the N1s peak intensity in the upstream modulation enhancement region was significantly higher than that in the downstream recognition enhancement region, while the C-O related characteristic peak intensity in the downstream recognition enhancement region was significantly higher than that in the upstream modulation enhancement region, indicating that the two types of groups had achieved differentiated grafting according to the predetermined regions. Dynamic contact angle testing showed that the wetting front advancement velocity of the gas contact surface in Example 2 was 3.1 mm / s to 3.4 mm / s, significantly faster than that of Comparative Group A (2.2 mm / s to 2.4 mm / s), indicating that the presence of the weakly basic modulation group enhancement region facilitated the rapid and stable establishment of a trace wetting layer in the upstream region. Surface elemental analysis after 8 hours of continuous operation revealed that the boron enrichment signal in the downstream recognition enhancement region of Example 2 was significantly stronger than that in the upstream modulation enhancement region, indicating that boron-containing impurities were selectively bound downstream after completing local transformation upstream.

[0049] Furthermore, to evaluate the repeatability of this embodiment, three interface materials were prepared in parallel using the same preparation method and run in the pre-absorption boron selective depletion section, respectively. The test results showed that the boron content in the primary electronic-grade ammonia water corresponding to the three interface materials was 0.88 μg / L, 0.91 μg / L, and 0.97 μg / L, respectively, with small fluctuations between groups, indicating that this interface construction method has good preparation consistency.

[0050] In summary, this embodiment sequentially constructs a weakly basic modulating group and an ortho-hydroxyl recognition group on the surface of a high-purity inert porous carrier, and forms a confined micro-hydration selective interface through a back-side micro-water supply channel. This allows boron-containing volatile impurities, or boron-containing impurities that coordinate or associate with ammonia, to first form locally transformed species in the upstream region before entering the subsequent ultrapure water absorption section, and then be selectively bound in the downstream region, thereby achieving directional retention before absorption. Example 3 The water supply rate of the micro-water supply channel is adjusted in conjunction with the flow rate of the ammonia-containing main gas flow to maintain a continuous micro-wetting layer without free droplet shedding, and to ensure that the local water activity at the confined micro-hydration selective interface is lower than that in the ultrapure water absorption section. Along the flow direction of the ammonia-containing main gas flow, the confined micro-hydration selective interface includes an upstream region and a downstream region. In the upstream region, the distribution density of weakly basic modulating groups is greater than the distribution density of ortho-hydroxyl recognition groups, and in the downstream region, the distribution density of ortho-hydroxyl recognition groups is greater than the distribution density of weakly basic modulating groups. The outlet of the boron selective depletion section before absorption is directly connected to the inlet of the ultrapure water absorption section through a closed conveying channel, so that the ammonia-containing main gas flow after being treated by the boron selective depletion section before absorption enters the ultrapure water absorption section without intermediate storage. This embodiment is based on Embodiments 1 and 2, wherein the liquid ammonia vaporization conditions, the basic structure of the pre-absorption boron selective depletion section, the construction method of the immobilized boron recognition sites, and the operating conditions of the ultrapure water absorption section, the multi-stage membrane separation section, and the ion adsorption polishing section are all consistent with Embodiments 1 and 2. This embodiment focuses on illustrating the linkage control method between the micro-water supply rate and the ammonia-containing main gas flow rate, the zoned density control method along the flow direction of the confined micro-hydration selective interface, and the impact of the direct connection method between the pre-absorption boron selective depletion section and the ultrapure water absorption section on the continuous operation stability of the system.

[0051] In this embodiment, the boron selective depletion section before absorption still employs a high-purity inert porous carrier and a confined micro-hydration selective interface structure. To achieve coordinated regulation, a mass flow control valve is installed at the inlet of the micro-water supply channel, and a gas mass flow meter is installed at the inlet of the ammonia-containing main gas flow. A controller is used to establish a linkage between the water supply rate and the ammonia-containing main gas flow rate. Preliminary experiments have shown that when the ammonia-containing main gas flow rate is stabilized at 2.78 Nm³, the optimal flow rate is achieved. 3 / h to 2.94Nm 3 Within the range of / h, if the micro-water supply rate is controlled within the range of 0.78 mL / min to 0.96 mL / min, and the ratio of the water supply rate to the ammonia-containing main gas flow rate is maintained at 0.28 mL·min -1 / Nm 3 ·h -1 Up to 0.34 mL·min-1 / Nm 3 ·h -1 Within this range, a stable micro-wetting layer can be formed on the surface of a high-purity inert porous support. This micro-wetting layer maintains a continuously spreading state during continuous operation, without visible free droplet shedding, and the local water activity at the confined micro-hydration selective interface is always lower than the water activity of the subsequent ultrapure water absorption section.

[0052] During actual operation, the flow rate of the ammonia-containing main gas stream obtained after liquid ammonia vaporization is controlled at 2.86 Nm. 3 The flow rate of the micro-water supply channel is set to 0.90 mL / min. When the flow rate of the ammonia-containing main gas flow changes within a short-term fluctuation range, the controller automatically adjusts the water supply rate according to the linkage ratio to synchronize the correction. For example, when the flow rate of the ammonia-containing main gas flow increases to 2.92 Nm³ / h... 3 When the flow rate is / h, the water supply rate is simultaneously increased to 0.94mL / min; when the flow rate of the main ammonia-containing gas stream is reduced to 2.80Nm 3 At a rate of / h, the water supply rate is simultaneously reduced to 0.86 mL / min. This method maintains the steady-state water holding capacity of the gas contact surface at 2.0 mg / cm³. 2 Up to 2.4 mg / cm 2 Within the specified range. During continuous operation, no free droplets were observed to detach from the gas contact surface, and the pressure drop in the boron selective depletion section before absorption remained between 2.2 kPa and 2.6 kPa, indicating that this linkage control method can maintain stable interface operation.

[0053] To correspond to the distribution density relationship between the upstream and downstream regions of the confined microhydration selective interface, in this embodiment, the confined microhydration selective interface is divided into an upstream region, a transition region, and a downstream region along the flow direction of the ammonia-containing main gas flow. The upstream region accounts for 30% of the total interaction length, the transition region accounts for 10%, and the downstream region accounts for 60%. The distribution density of the weakly basic modulating groups in the upstream region is controlled at 1.18 μmol / cm². 2 Up to 1.25 μmol / cm 2 The distribution density of the ortho-hydroxy recognition group was controlled to be 0.42 μmol / cm³. 2 Up to 0.49 μmol / cm 2 The distribution density of the ortho-hydroxy recognition group in the downstream region was controlled at 1.56 μmol / cm³. 2 Up to 1.70 μmol / cm 2 The distribution density of the weakly basic modulating group was controlled at 0.38 μmol / cm². 2 Up to 0.46 μmol / cm 2In the transition region, both types of groups transition gradually through a gradient. This distribution pattern allows boron-containing volatile impurities, or boron-containing impurities that coordinate or associate with ammonia, to preferentially form locally transformed species in the upstream region. Subsequently, they are selectively bound by ortho-position polyhydroxy recognition groups in the downstream region, thus achieving a continuous upstream-promoted transformation and downstream-promoted binding process.

[0054] To accommodate the direct connection method, in this embodiment, the outlet of the pre-absorption boron selective depletion section and the inlet of the ultrapure water absorption section are directly connected by a 180mm long, closed PFA transport channel with an inner diameter of 8mm. No intermediate buffer tanks, temporary storage containers, or open maintenance ports are installed within the connection section. After the ammonia-containing main gas stream, treated by the pre-absorption boron selective depletion section, leaves this section, it immediately enters the ultrapure water absorption section for absorption. The average residence time of the entire transport process is controlled within 0.12s. This method reduces the chance of redistribution of residual boron-containing impurities after directional reduction by the pre-absorption boron selective depletion section in the intermediate space and lowers the probability of reverse dissociation and re-migration of locally transformed species.

[0055] Three comparison groups were set up. In comparison group D, the linkage between the water supply rate and the flow rate of the ammonia-containing main gas flow was removed, and the water supply rate was fixed at 0.90 mL / min. Other conditions were the same as in this embodiment. In comparison group E, the linkage water supply control was retained, but the distribution density of the weakly basic modulating groups and the ortho-hydroxyl recognition groups in the upstream and downstream regions was adjusted to be basically consistent, so as not to form obvious upstream high modulation and downstream high recognition zones. In comparison group F, the linkage water supply control and zoned density structure were retained, but an intermediate buffer tank with a volume of 0.8 L was added between the boron selective depletion section and the ultrapure water absorption section before absorption, so that the treated ammonia-containing main gas flow would be briefly stagnant before entering the ultrapure water absorption section. Each group of experiments was run continuously for 12 hours under the same raw material conditions. After reaching a stable state, samples were taken for testing, and the results are shown in Table 6.

[0056] Table 6: Operating control conditions and test results of Example 3 and the comparison group

[0057] As shown in Table 6, in this embodiment, when the water supply rate and the ammonia-containing main gas flow rate are controlled in a coordinated manner, the surface water holding capacity fluctuates within a small range, the pressure drop in the pre-absorption stage is relatively stable, and the boron content in both the primary electronic-grade ammonia water and the final product is at a low level. In comparison group D, due to the fixed water supply rate, when the ammonia-containing main gas flow rate fluctuates, the water holding capacity at the interface surface fluctuates significantly, leading to local instability of the confined micro-hydration selective interface. The boron content in the primary electronic-grade ammonia water increases to 1.36 μg / L, and the boron content in the final product increases to 0.47 μg / L. This indicates that coordinated control is not only a general process control measure, but also a necessary condition for maintaining the stable existence of the confined micro-hydration selective interface.

[0058] Although the interaction between water supply and airflow was retained in comparative group E, the boron content in the primary electronic-grade ammonia water increased to 1.53 μg / L because the weakly basic modulating group and the ortho-position polyhydroxy recognition group did not form a partitioned density structure with high upstream modulation and high downstream recognition. This result indicates that without a partitioned density difference along the main ammonia-containing airflow direction, even if both types of groups are present simultaneously, it is difficult to form a continuous process of modulation followed by recognition. This demonstrates that the distribution density relationship between the upstream and downstream regions is crucial for enhancing the interfacial reduction of boron-containing impurities.

[0059] In Comparative Group F, after adding an intermediate buffer tank between the boron selective depletion section before absorption and the ultrapure water absorption section, although the front-end interface state and partition density structure remained unchanged, the boron content in the primary electronic-grade ammonia water and the boron content in the final product were both higher than in this embodiment. Operational observation revealed short-term retention and localized backflow in the intermediate buffer tank, indicating that if the ammonia-containing main gas flow after treatment in the boron selective depletion section before absorption is not directly introduced into the ultrapure water absorption section, the chance of residual boron-containing impurities migrating again will increase. Therefore, directly connecting the sections through a closed conveying channel helps maintain the directional reduction effect before absorption and reduces the risk of recontamination.

[0060] To further evaluate the continuous operation stability of this embodiment, the system was run continuously for 36 hours using the operating mode of this embodiment, with samples taken and tested every 6 hours. The results are shown in Table 7. Table 7: Stability Results of Continuous Operation in Example 3

[0061] As shown in Table 7, during 36 hours of continuous operation, the surface water holding capacity of the confined micro-hydration selective interface in this embodiment remained at 2.1 mg / cm³. 2 Up to 2.4 mg / cm 2 Between these points, the pressure drop in the pre-absorption section only increased slightly, and the boron content in the primary electronic-grade ammonia water and the final product fluctuated little. This indicates that by adjusting the water supply and airflow in tandem, controlling the density in different zones, and directly connecting with the ultrapure water absorption section, the boron selection depletion section before absorption can maintain good stability and repeatability during continuous operation.

[0062] In summary, this embodiment achieves stable local water activity at the confined micro-hydration selective interface by adjusting the water supply rate of the micro-water supply channel in conjunction with the flow rate of the ammonia-containing main gas flow. Simultaneously, by setting up a partitioned density structure with high upstream modulation and high downstream recognition along the flow direction of the ammonia-containing main gas flow, boron-containing volatile impurities or boron-containing impurities that form coordination or association relationships with ammonia can sequentially complete local transformation and selective binding at the interface. Furthermore, by directly connecting the boron selective depletion section before absorption with the ultrapure water absorption section, the risk of re-migration caused by intermediate retention is reduced.

[0063] In the description of this specification, references to terms such as "an embodiment," "example," "specific example," etc., indicate that a specific feature, structure, material, or characteristic described in connection with that embodiment or example is included in at least one embodiment or example of the invention. In this specification, illustrative expressions of the above terms do not necessarily refer to the same embodiment or example. Furthermore, the specific features, structures, materials, or characteristics described may be combined in any suitable manner in one or more embodiments or examples.

[0064] The foregoing has shown and described the basic principles, main features, and advantages of the present invention. Those skilled in the art should understand that the present invention is not limited to the above embodiments. The embodiments and descriptions in the specification are merely illustrative of the principles of the present invention. Various changes and modifications can be made to the present invention without departing from its spirit and scope, and all such changes and modifications fall within the scope of the present invention as claimed.

Claims

1. A multi-stage membrane separation and ion adsorption method for removing impurities from electronic-grade ammonia water, characterized in that, Includes the following steps: S1. The raw material liquid ammonia is vaporized to obtain an ammonia-containing main gas flow, and the ammonia-containing main gas flow is stabilized and the entrained droplets are controlled. S2. The ammonia-containing main gas flow is introduced into the pre-absorption boron selective depletion section. The pre-absorption boron selective depletion section includes a high-purity inert porous support and a confined microhydration selective interface constructed on the surface of the high-purity inert porous support. The confined microhydration selective interface is provided with immobilized boron recognition sites. S3. Control the local water activity of the confined micro-hydration selective interface to be lower than that of the subsequent ultrapure water absorption section, so that the boron-containing volatile impurities or boron-containing impurities that form coordination or association relationships with ammonia in the ammonia-containing main gas flow preferentially enter the confined micro-hydration selective interface, and form local transformation species under the action of the immobilized boron recognition sites, so as to directionally intercept the boron-containing volatile impurities or boron-containing impurities that form coordination or association relationships with ammonia, while inhibiting the large-scale absorption of ammonia in the boron selective depletion section before absorption; S4. The ammonia-containing main gas flow after being treated by the boron selection depletion section before absorption is introduced into the ultrapure water absorption section for absorption to obtain primary electronic grade ammonia water. S5. The primary electronic grade ammonia water is introduced into a multi-stage membrane separation section, and particulate impurities, colloidal impurities, micro-cluster impurities and residual separable associative compounds are removed in stages by at least two membrane separation units. S6. The electronic-grade ammonia water processed by the multi-stage membrane separation section is introduced into the ion adsorption polishing section to adsorb and remove residual trace metal ions and anionic impurities, thereby obtaining the electronic-grade ammonia water product.

2. The method for multi-stage membrane separation and ion adsorption impurity removal of electronic-grade ammonia water according to claim 1, characterized in that, The immobilized boron recognition site includes a weakly basic modulating group and an ortho-hydroxyl recognition group disposed on the confined microhydration selective interface. The weakly basic modulating group is used to promote the formation of the locally transformed species by the boron-containing volatile impurities or boron-containing impurities that form coordination or association relationships with ammonia. The ortho-hydroxyl recognition group is used to selectively bind to the locally transformed species.

3. The method for multi-stage membrane separation and ion adsorption impurity removal of electronic-grade ammonia water according to claim 2, characterized in that, The weakly basic modulating group and the ortho-hydroxyl recognition group are sequentially arranged along the flow direction of the ammonia-containing main gas flow, so that the boron-containing volatile impurities or boron-containing impurities that form coordination or association relationships with ammonia first form the locally transformed species, and are then selectively bound by the ortho-hydroxyl recognition group.

4. The method for multi-stage membrane separation and ion adsorption impurity removal of electronic-grade ammonia water according to claim 3, characterized in that, The confined micro-hydration selection interface introduces ultrapure water into the interior of the high-purity inert porous carrier through a micro-water supply channel located on the side of the high-purity inert porous carrier away from the ammonia-containing main gas flow. Under capillary migration, the ultrapure water forms a micro-wetting layer on the side of the high-purity inert porous carrier that is in contact with the ammonia-containing main gas flow.

5. The method for multi-stage membrane separation and ion adsorption impurity removal of electronic-grade ammonia water according to claim 4, characterized in that, The water supply rate of the micro-water supply channel is adjusted in conjunction with the flow rate of the ammonia-containing main gas flow, so that the micro-wetting layer remains continuous and no free droplets fall off, and the local water activity of the confined micro-hydration selective interface is lower than that of the ultrapure water absorption section.

6. The method for multi-stage membrane separation and ion adsorption impurity removal of electronic-grade ammonia water according to claim 5, characterized in that, Along the flow direction of the ammonia-containing main gas flow, the confined micro-hydration selective interface includes an upstream region and a downstream region. In the upstream region, the distribution density of the weakly basic modulating group is greater than the distribution density of the ortho-hydroxyl recognition group, and in the downstream region, the distribution density of the ortho-hydroxyl recognition group is greater than the distribution density of the weakly basic modulating group.

7. The method for multi-stage membrane separation and ion adsorption impurity removal of electronic-grade ammonia water according to claim 6, characterized in that, The outlet of the pre-absorption boron selective depletion section is directly connected to the inlet of the ultrapure water absorption section through a closed conveying channel, so that the ammonia-containing main gas flow after being treated by the pre-absorption boron selective depletion section enters the ultrapure water absorption section without intermediate storage.

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