Electronic-grade sulfuric acid deep impurity removal production process based on dynamic cyclic adsorption

Abstract

The invention relates to the technical field of production of electronic chemicals, and discloses an electronic grade sulfuric acid deep impurity removal production process based on dynamic cycle adsorption, which comprises the following steps: preparing an adsorbent, providing mesoporous silica gel loaded with dithizone-phosphonic acid difunctional groups as the adsorbent, the pore size of the mesoporous silica gel being 10-50nm, and the specific surface area being greater than 500m / g; the method comprises the following steps: constructing a system, namely establishing a double-adsorption-column dynamic circulating system, dividing the interior of an adsorption column into a saturated region, a mass transfer region and an unpolluted region, and controlling an electronic-grade sulfuric acid solution to continuously flow at a constant flow speed at 30-45 DEG C through a programmable logic controller (PLC); and adsorption operation. According to the invention, the dithizone-phosphonic acid bifunctional group accurately captures metal cation impurities in electronic-grade sulfuric acid through the strong coordination ability of sulfur atoms and transition metal ions, and a double-site synergistic adsorption mechanism is formed.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of electronic chemical production, in particular to an electronic-grade sulfuric acid deep impurity removal production process based on dynamic circulation adsorption. BACKGROUND

[0002] Sulfuric acid is a strong inorganic acid that can react with most metals. High concentration sulfuric acid has strong water absorption, and can be used as a dehydrating agent to carbonize wood, paper, cotton and linen fabrics, and biological skin and meat containing carbohydrates. When mixed with water, it will also release a large amount of heat energy. It has strong corrosive and oxidizing properties, and sulfuric acid is an important industrial raw material, known as the "mother of chemical industry", which can be used to manufacture fertilizers, drugs, explosives, pigments, detergents, batteries, etc., and is also widely used in petroleum purification, metal smelting, and dye industries. It is commonly used as a chemical reagent and can be used as a dehydrating agent and sulfonating agent in organic synthesis.

[0003] At present, there are many technical bottlenecks in the production process of electronic-grade sulfuric acid deep impurity removal based on dynamic circulation adsorption. When the adsorbent regeneration is switched, the system cannot judge the chemical stability state of the functional groups in the regeneration process in real time. When irreversible degradation of functional groups occurs on the surface of the adsorbent, it will lead to a decrease in the selectivity of subsequent adsorption, making it difficult to ensure the stability of impurity removal efficiency.

[0004] Therefore, the present application proposes an electronic-grade sulfuric acid deep impurity removal production process based on dynamic circulation adsorption to solve the above problems. SUMMARY

[0005] The main purpose of the present application is to provide an electronic-grade sulfuric acid deep impurity removal production process based on dynamic circulation adsorption to solve the problems raised in the above background.

[0006] To achieve the above purpose, the technical scheme adopted by the present application is as follows: an electronic-grade sulfuric acid deep impurity removal production process based on dynamic circulation adsorption, comprising the following steps: Step 1: adsorbent preparation, providing mesoporous silica gel loaded with dithizone-phosphonic acid bifunctional groups as adsorbent, the pore size of the mesoporous silica gel is 10-50 nm, and the specific surface area is greater than 500 m 2 / g; Step 2: system construction, establishing a double-adsorption-column dynamic circulation system, the inside of the adsorption column is divided into a saturated zone, a mass transfer zone and an unpolluted zone, and the electronic-grade sulfuric acid solution is controlled to flow continuously at a constant flow rate at 30-45℃ by a programmable logic controller (PLC); Step 3: adsorption operation, introducing electronic-grade sulfuric acid raw materials into the double-adsorption-column dynamic circulation system for adsorption treatment, and simultaneously setting an online metal ion sensor at the outlet of the adsorption column to monitor the impurity concentration in real time; Step four: Regeneration switching, when the impurity concentration detected by the online metal ion sensor reaches the preset threshold, the regeneration mode is automatically triggered, which includes an elution stage and an activation stage; Step five: Regeneration operation, in the elution stage, the saturated adsorption column is washed countercurrently with 0.5-2.0 mol / L dilute hydrochloric acid to desorb metal ions, and in the activation stage, after the adsorption column is washed with ultrapure water to neutralization, it is dried by nitrogen blowing; Step six: Cycle control, after regeneration, the adsorption column automatically switches back to the working sequence and alternately operates with another adsorption column to realize continuous production.

[0007] Preferably, the mesoporous silica gel is prepared by the following method: Step one: Synthesis of mesoporous silica gel carrier Ⅰ. Synthesis of base by sol-gel method: TEOS and CTAB are dissolved in an ethanol / water mixed solution at a molar ratio of 1:0.3, the pH is adjusted to 10-11, and the white colloid is formed by stirring at 40°C for 24 hours with ammonia as catalyst; Ⅱ. Template removal and activation: The solid is centrifuged and calcined at 550°C for 6 hours to remove the CTAB template; A silica gel carrier with a pore size of 30 nm±5 nm and a specific surface area of 750 m 2 / g is obtained; Step two: Difunctional group loading Ⅰ. Preparation of difunctional solution: Dithizone and phosphonic acid are dissolved in anhydrous ethanol at a molar ratio of 1:1.8; 3-Aminopropyl triethoxysilane (APTES) crosslinking agent is added, accounting for 5% of the solution mass; Ⅱ. Post-treatment: Ethanol is washed 3 times to remove physically adsorbed molecules; The mesoporous structure is retained by vacuum drying at 90°C for 4 hours, and the mesoporous silica gel is obtained; The adsorbent is prepared by the following method: The mesoporous silica gel carrier is soaked in a difunctional solution containing dithizone and phosphonic acid, and the reaction is carried out at 40-60°C for 2-4 hours, with a molar ratio of dithizone to phosphonic acid of 1:1.5-2.0; After the reaction, filtration is performed, ethanol is washed 3 times, and vacuum drying is carried out at 80-100°C for 3-5 hours; The obtained adsorbent has a difunctional group loading of 5-10 wt%.

[0008] Preferably, in the double-adsorption-column dynamic circulation system: The double adsorption column is in parallel structure, the ratio of height to diameter is 5:1-8:1, and the material is hastelloy; The volume ratio of the saturation zone, mass transfer zone and non-polluted zone is 1:2:1. The flow rate is controlled by PLC at 5-15 m / h, the temperature is 29-46℃, and the system pressure is 0.5-1.0 MPa. 3 The flow rate is controlled by PLC at 5-15 m / h, the temperature is 29-46℃, and the system pressure is 0.5-1.0 MPa.

[0009] Preferably, the online metal ion sensor comprises: The online metal ion sensor is inductively coupled plasma mass spectrometer (ICP-MS) or atomic absorption spectrometer (AAS), and the monitoring targets include Fe 3+ , Cu 2+ , Pb 2+ , As 3+ . The preset threshold is 0.05 ppb, and the sampling frequency is 1-5 times per second. The PLC calculates the concentration trend according to the preset algorithm and triggers the regeneration in advance for 10-30 seconds.

[0010] Preferably, the automatic triggering of the regeneration switch comprises the following logic: When the regeneration switch is triggered, the PLC closes the inlet valve of the working column and opens the standby column within 2-5 minutes. The elution stage lasts for 20-40 minutes, and the activation stage lasts for 30-60 minutes. The PLC records the saturation degree of the adsorbent and optimizes the timing of the next regeneration.

[0011] Preferably, the specific operation in step five comprises: Elution stage: dilute hydrochloric acid concentration 0.5-2.0 mol / L, counter-current flow rate 2-5 m 3 / h, pressure 0.3-0.8 MPa; The waste acid liquid is separated by a membrane to recover hydrochloric acid, and the recovery rate is greater than 85%. Activation stage: ultrapure water conductivity less than 0.1 μS / cm, elution to outlet pH 6.5-7.5, nitrogen blowing pressure 0.2-0.5 MPa, and final adsorbent water content less than 0.5%.

[0012] Preferably, step five further comprises: The activation stage increases the adsorbent strengthening treatment: injection of 0.1-0.5 wt% dithizone ethanol solution, 35-45℃ soaking for 10-20 minutes; followed by ultrapure water elution and 50-60℃ hot nitrogen blowing for 10-15 minutes; The adsorbent cycle life is greater than 100 times, and the adsorption capacity attenuation after single regeneration is less than 1%.

[0013] Preferably, the cycle control comprises: The PLC adopts a fuzzy control algorithm to dynamically adjust the alternating period of the adsorption column. The switching frequency is once every 8-24 hours, and the parallel time of the system double column accounts for more than 95%. The purity of the product electronic-grade sulfuric acid is greater than 99.999%, and the total amount of metal impurities is less than 0.1 ppb.

[0014] Preferably, the production process further comprises a pretreatment step: The electronic-grade sulfuric acid raw material is first filtered through a 0.1-0.5 μm precision filter to remove particulate impurities; After preheating to 30-45℃, it enters the adsorption system, and the suspended solids content is less than 1 ppb.

[0015] Preferably, the waste acid liquid membrane recovery treatment specifically includes: After the waste acid liquid is separated and recovered by the membrane, the residual waste liquid enters the neutralization treatment unit, calcium hydroxide is added to adjust the pH to the neutral range, and the residual metal ions form hydroxide precipitates; After neutralization, the solution is subjected to solid-liquid separation by a plate and frame filter press, and the obtained filtrate is returned to the pretreatment step as a rinse water source for the precision filter; The operating pressure of the plate and frame filter press is controlled in the medium-low pressure range, and the moisture content of the filter cake is controlled within a preset range.

[0016] The present application has the following beneficial effects: 1. In the present application, the dithizone-phosphonic acid bifunctional group precisely captures metal cation impurities in electronic-grade sulfuric acid through the strong coordination ability of sulfur atoms with transition metal ions, while the phosphonic acid group efficiently adsorbs anion impurities through electrostatic attraction, forming a dual-site synergistic adsorption mechanism; the mesoporous silica gel carrier constructs an ion sieve barrier by virtue of the nanoscale regular pore structure, blocking the entry of macromolecular organic impurities into the adsorption active site, achieving simultaneous deep removal of multi-component impurities at the molecular scale, and improving the impurity retention capacity and adsorption selectivity.

[0017] 2. In the present application, the double adsorption column dynamic circulation system precisely maintains the ion exchange front under automatic control through hierarchical separation design; real-time monitoring of impurity concentration and intelligent triggering of the regeneration program realize continuous and stable operation; in the regeneration stage, gradient countercurrent washing process is adopted, first desorbing impurities with dilute acid solution, then purifying the residue with ultrapure water, and finally recovering the adsorbent activity through gas blowing, forming a closed-loop regeneration control chain to avoid the risk of secondary release of impurities.

[0018] 3. In the present application, the adsorbent regeneration enhancement treatment restores the damaged functional groups through in-situ repair technology, and strengthens the microporous structure by gas activation; the process forms a stable self-repairing protective layer on the surface of the adsorbent, enhances the stability of the functional groups; combined with the waste liquid recovery technology, it simultaneously realizes the extension of the adsorbent cycle life and the simplification of the regeneration waste liquid discharge, and comprehensively guarantees the environmental friendliness and economic sustainability of the production process. DETAILED DESCRIPTION

[0019] The technical solutions in the embodiments of the present application will be described below in a clear and complete manner. Obviously, the described embodiments are only a part of the embodiments of the present application, rather than all the embodiments. Based on the embodiments in the present application, all other embodiments obtained by those of ordinary skill in the art without creative labor fall within the scope of protection of the present application.

[0020] Implementation I: electronic-grade sulfuric acid deep impurity removal production process based on dynamic circulation adsorption, comprising the following steps: Step one: adsorbent preparation, providing mesoporous silica gel loaded with dithizone-phosphonic acid bifunctional groups as adsorbent, the pore size of the mesoporous silica gel is 10 nm, and the specific surface area is greater than 500 m 2 / g; Step two: system construction, establishing a double-adsorption-column dynamic circulation system, dividing the inside of the adsorption column into saturated zone, mass transfer zone and uncontaminated zone, and controlling the electronic-grade sulfuric acid solution to flow continuously at a constant flow rate at 30°C through a programmable logic controller (PLC); Step three: adsorption operation, introducing electronic-grade sulfuric acid raw materials into the double-adsorption-column dynamic circulation system for adsorption treatment, and setting an online metal ion sensor at the outlet of the adsorption column to monitor the impurity concentration in real time; Step four: regeneration switching, when the impurity concentration detected by the online metal ion sensor reaches the preset threshold value, the regeneration mode is automatically triggered, which includes an elution stage and an activation stage; Step five: regeneration operation, in the elution stage, 0.5 mol / L dilute hydrochloric acid is used to reverse flush the saturated adsorption column to desorb metal ions, in the activation stage, after the adsorption column is washed with ultrapure water to neutralize, it is dried by nitrogen blowing; Step six: cycle control, after regeneration, the adsorption column automatically switches back to the working sequence and alternately runs with the other adsorption column to realize continuous production.

[0021] The mesoporous silica gel is prepared by the following method: Step one: synthesis of mesoporous silica gel carrier I. Synthesis of base by sol-gel method: TEOS and CTAB were dissolved in an ethanol / water mixture with a molar ratio of 1:0.3, and the pH was adjusted to 10. The mixture was stirred at 40°C for 24 hours to form a white gel; II. Template removal and activation: The solid was centrifuged and calcined at 550°C for 6 hours to remove the CTAB template; A silica gel carrier with a pore size of 25 nm and a specific surface area of 750 m 2 / g was obtained; Step two: bifunctional group loading I. Preparation of bifunctional solution: Dithizone and phosphonic acid were dissolved in anhydrous ethanol with a molar ratio of 1:1.8; 3-Aminopropyltriethoxysilane (APTES) crosslinking agent was added, accounting for 5% of the solution mass; II. Post-treatment: Ethanol was washed three times to remove physically adsorbed molecules; The mesoporous silica gel was obtained by vacuum drying at 90°C for 4 hours, retaining the mesoporous structure; The adsorbent was prepared by the following method: The mesoporous silica gel carrier was immersed in a bifunctional solution containing dithizone and phosphonic acid, and reacted at 40°C for 2 hours, with a molar ratio of dithizone to phosphonic acid of 1:1.5; After the reaction, the solution was filtered and washed three times with ethanol, and then vacuum dried at 80°C for 3 hours; The obtained adsorbent had a bifunctional group loading of 5wt%.

[0022] In the double-adsorption-column dynamic circulation system: The double-adsorption columns were in parallel structure with a height-to-diameter ratio of 5:1 and were made of hastelloy; The volume ratio of the saturation zone, mass transfer zone, and uncontaminated zone was 1:2:1; The flow rate was controlled by PLC at 5 m 3 / h, the temperature was 29°C, and the system pressure was 0.5 MPa.

[0023] The online metal ion sensor included: The online metal ion sensor was an inductively coupled plasma mass spectrometer (ICP-MS) or an atomic absorption spectrometer (AAS), and the monitoring targets included Fe 3+ , Cu 2+ , Pb 2 +, and As 3+ ; The preset threshold was 0.05 ppb, and the sampling frequency was 1 time / s; PLC calculated the concentration trend according to the preset algorithm and triggered regeneration 10 seconds in advance.

[0024] The automatic triggering of regeneration switching includes the following logic: When the regeneration switching, the PLC closes the working column inlet valve and opens the standby column within 2 minutes; The elution stage lasts for 20 minutes, and the activation stage lasts for 30 minutes; The PLC records the saturation of the adsorbent and optimizes the timing of the next regeneration.

[0025] The specific operation in step five includes: Elution stage: dilute hydrochloric acid concentration 0.5 mol / L, countercurrent flow rate 2 m 3 / h, pressure 0.3 MPa; The waste acid solution is recovered by membrane separation to recover hydrochloric acid, with a recovery rate of more than 85%; Activation stage: ultrapure water conductivity less than 0.1 μS / cm, elution to outlet pH 6.5, nitrogen blowing pressure 0.2 MPa, final adsorbent water content less than 0.5%.

[0026] Step five also includes: Activation stage increases adsorbent strengthening treatment: injection of 0.1 wt% dithizone ethanol solution, 35℃ soaking for 10 minutes; Subsequently, ultrapure water elution and 50℃ hot nitrogen blowing for 10 minutes; The adsorbent cycle life is greater than 100 times, and the adsorption capacity attenuation after single regeneration is less than 1%.

[0027] The cycle control includes: PLC uses fuzzy control algorithm to dynamically adjust the adsorption column alternating period; The switching frequency is once every 8 hours, and the system double-column parallel time ratio is greater than 95%; The product electronic grade sulfuric acid purity is greater than 99.999%, and the total amount of metal impurities is less than 0.1 ppb.

[0028] The production process also includes a pretreatment step: The electronic grade sulfuric acid raw material is first passed through a 0.1 μm precision filter to remove particulate impurities; After preheating to 30℃, it enters the adsorption system, with suspended solids content less than 1 ppb.

[0029] The waste acid solution is treated by membrane recovery, which includes: After the waste acid solution is recovered by membrane separation to recover hydrochloric acid, the residual waste liquid generated is sent to a neutralization treatment unit, and calcium hydroxide is added to adjust the pH to the neutral range, so that the residual metal ions form hydroxide precipitates; After neutralization, the solution is subjected to solid-liquid separation by a plate and frame filter press, and the obtained filtrate is returned to the pretreatment step as the rinse water source for the precision filter; The operating pressure of the plate and frame filter press is controlled in the medium-low pressure range, and the moisture content of the filter cake is controlled within the preset range.

[0030] Implementation two: electronic grade sulfuric acid deep impurity removal production process based on dynamic cycle adsorption, including the following steps: Step one: adsorbent preparation, providing mesoporous silica gel loaded with dithizone-phosphonic acid bifunctional groups as adsorbent, the pore size of mesoporous silica gel is 30 nm, and the specific surface area is greater than 500 m 2 / g; Step two: system construction, establishing a double-adsorption-column dynamic cycle system, dividing the inside of the adsorption column into saturated zone, mass transfer zone and uncontaminated zone, and controlling the continuous flow of electronic grade sulfuric acid solution at a constant flow rate at 40℃ through programmable logic controller PLC; Step three: adsorption operation, introducing electronic grade sulfuric acid raw materials into the double-adsorption-column dynamic cycle system for adsorption treatment, and setting an online metal ion sensor at the outlet of the adsorption column to monitor the impurity concentration in real time; Step four: regeneration switching, when the impurity concentration detected by the online metal ion sensor reaches the preset threshold, automatically triggering the regeneration mode, which includes elution stage and activation stage; Step five: regeneration operation, in the elution stage, using 1.0 mol / L dilute hydrochloric acid to reverse flush the saturated adsorption column to desorb metal ions, in the activation stage, using ultrapure water to leach the adsorption column to neutral, and then using nitrogen to dry; Step six: cycle control, after regeneration, the adsorption column automatically switches back to the working sequence and alternately operates with the other adsorption column to realize continuous production.

[0031] The mesoporous silica gel is prepared by the following method: Step one: synthesis of mesoporous silica gel carrier Ⅰ. Synthesis of base by sol-gel method: Dissolve tetraethyl orthosilicate (TEOS) and cetyltrimethylammonium bromide (CTAB) in an ethanol / water mixed solution at a molar ratio of 1:0.3; adjust the pH to 10.5, catalyze with ammonia, stir at 40℃ for 24 hours to form a white colloid; Ⅱ. Template removal and activation: Centrifugal separation of solid, calcination at 550℃ for 6 hours to remove CTAB template Obtain silica gel carrier with pore size of 30 nm and specific surface area of 750 m 2 / g; Step two: bifunctional group loading Ⅰ. Preparation of bifunctional solution: Dissolve dithizone and phosphonic acid in anhydrous ethanol at a molar ratio of 1:1.8; Add 3-aminopropyl triethoxysilane (APTES) crosslinking agent, accounting for 5% of the solution mass; Ⅱ. Post-treatment: Wash with ethanol for 3 times to remove physically adsorbed molecules; 90℃ vacuum drying for 4 hours, retaining mesoporous structure, obtaining the mesoporous silica gel; The adsorbent is prepared by the following method: The mesoporous silica gel carrier is immersed in a bifunctional solution containing dithizone and phosphonic acid, and reacted at 50℃ for 3 hours, with a molar ratio of dithizone to phosphonic acid of 1:1.7; After reaction, filtration, ethanol washing 3 times, 90℃ vacuum drying for 4 hours; The obtained adsorbent bifunctional group loading is 8wt%.

[0032] In the double-adsorption-column dynamic circulation system: The double-adsorption-column is in parallel structure, with a height-to-diameter ratio of 7:1, and the material is Hastelloy; The volume ratio of saturation zone, mass transfer zone, and uncontaminated zone is 1:2:1; PLC controls the flow rate of 10m 3 / h, temperature 35℃, system pressure 0.8MPa.

[0033] The online metal ion sensor includes: The online metal ion sensor is inductively coupled plasma mass spectrometer ICP-MS or atomic absorption spectrometer AAS, and the monitoring targets include Fe 3+ , Cu 2+ , Pb 2 +, As 3+ ; The preset threshold is 0.05ppb, and the sampling frequency is 3 times / second; PLC calculates the concentration trend according to the preset algorithm and triggers regeneration 20 seconds in advance.

[0034] The automatic triggering of regeneration switching includes the following logic: When the regeneration switching is performed, the PLC closes the working column inlet valve and opens the standby column within 3 minutes; The elution stage lasts for 30 minutes, and the activation stage lasts for 50 minutes; PLC records the saturation of the adsorbent and optimizes the timing of the next regeneration.

[0035] The specific operation in step five includes: Elution stage: dilute hydrochloric acid concentration 1.0mol / L, countercurrent flow rate 4m 3 / h, pressure 0.5MPa; The waste acid liquid is separated by membrane to recover hydrochloric acid, with a recovery rate of more than 85%; Activation stage: ultrapure water conductivity less than 0.1μS / cm, elution to outlet pH 7.0, nitrogen blowing pressure 0.4MPa, final adsorbent water content less than 0.5%.

[0036] In step five, it also includes: Activation stage increases adsorbent reinforcement treatment: inject 0.3wt% dithizone ethanol solution, soak at 35-45℃ for 15 minutes; Subsequently, rinse with ultrapure water and blow with hot nitrogen at 55℃ for 12 minutes; The adsorbent cycle life is greater than 100 times, and the adsorption capacity attenuation after single regeneration is less than 1%.

[0037] The cycle control includes: PLC uses fuzzy control algorithm to dynamically adjust the alternating period of the adsorption column; The switching frequency is once every 12 hours, and the system double-column parallel time ratio is greater than 95%; The purity of electronic grade sulfuric acid is greater than 99.999%, and the total amount of metal impurities is less than 0.1ppb.

[0038] The production process also includes a pretreatment step: The electronic grade sulfuric acid raw material is first filtered through a 0.3μm precision filter to remove particulate impurities; After preheating to 35℃, it enters the adsorption system, and the suspended solids content is less than 1ppb.

[0039] The membrane recovery treatment of waste acid solution specifically includes: After the waste acid solution is separated and recovered by the membrane, the residual waste liquid generated is introduced into the neutralization treatment unit, and calcium hydroxide is added to adjust the pH to the neutral range, so that the residual metal ions form hydroxide precipitates; After neutralization, the solution is subjected to solid-liquid separation by a plate and frame filter press, and the obtained filtrate is returned to the pretreatment step as the rinse water source for the precision filter; The operating pressure of the plate and frame filter press is controlled in the medium-low pressure range, and the moisture content of the filter cake is controlled within the preset range.

[0040] Implementation three: electronic grade sulfuric acid deep impurity removal production process based on dynamic cycle adsorption, including the following steps: Step one: adsorbent preparation, providing mesoporous silica gel loaded with dithizone-phosphonic acid bifunctional groups as adsorbent, the pore size of mesoporous silica gel is 50nm, and the specific surface area is greater than 500m 2 / g; Step two: system construction, establishing a double-adsorption column dynamic cycle system, dividing the adsorption column into saturated zone, mass transfer zone and uncontaminated zone, and controlling the continuous flow of electronic grade sulfuric acid solution at a constant flow rate at 45℃ through a programmable logic controller PLC; Step three: adsorption operation, introducing electronic grade sulfuric acid raw material into the double-adsorption column dynamic cycle system for adsorption treatment, while setting an online metal ion sensor at the outlet of the adsorption column to monitor the impurity concentration in real time; Step four: Regeneration switching, when the impurity concentration detected by the online metal ion sensor reaches the preset threshold, the regeneration mode is automatically triggered, which includes the elution stage and the activation stage; Step five: Regeneration operation, in the elution stage, the saturated adsorption column is washed countercurrently with 2.0 mol / L dilute hydrochloric acid to desorb metal ions, in the activation stage, after the adsorption column is washed with ultrapure water to neutralization, it is dried by nitrogen blowing; Step six: Cycle control, after the regeneration is completed, the adsorption column automatically switches back to the working sequence, and alternately operates with another adsorption column to realize continuous production.

[0041] The mesoporous silica gel is prepared by the following method: Step one: Synthesis of mesoporous silica gel carrier Ⅰ. Synthesis of base by sol-gel method: TEOS and CTAB are dissolved in an ethanol / water mixed solution at a molar ratio of 1:0.3; the pH is adjusted to 11, and ammonia is used as catalyst; stirring at 40°C for 24 hours to form a white colloid; Ⅱ. Template removal and activation: Centrifugal separation of solids, calcination at 550°C for 6 hours to remove the CTAB template; Obtaining a silica gel carrier with a pore size of 35 nm and a specific surface area of 750 m 2 / g; Step two: Difunctional group loading Ⅰ. Preparation of difunctional solution: Dithizone and phosphonic acid are dissolved in anhydrous ethanol at a molar ratio of 1:1.8; Add 3-aminopropyl triethoxysilane (APTES) crosslinking agent, which accounts for 5% of the solution mass; Ⅱ. Post-treatment: Wash with ethanol for 3 times to remove physically adsorbed molecules; Vacuum drying at 90°C for 4 hours to retain the mesoporous structure, obtaining the mesoporous silica gel; The adsorbent is prepared by the following method: Soak the mesoporous silica gel carrier in a difunctional solution containing dithizone and phosphonic acid, and react at 60°C for 4 hours, with a molar ratio of dithizone to phosphonic acid of 1:2.0; After the reaction, filter and wash with ethanol for 3 times, and vacuum dry at 100°C for 5 hours; The obtained adsorbent has a difunctional group loading of 10wt%.

[0042] In the double-adsorption-column dynamic circulation system: The double-adsorption-column is in parallel structure, with a height to diameter ratio of 8:1, and the material is hastelloy; The volume ratio of saturated zone, mass transfer zone, and uncontaminated zone is 1:2:1; PLC controls flow rate 15 m 3 / h, temperature 46℃, system pressure 1.0 MPa.

[0043] The online metal ion sensor includes: The online metal ion sensor is an inductively coupled plasma mass spectrometer ICP-MS or an atomic absorption spectrometer AAS, and the monitoring targets include Fe 3+ , Cu 2+ , Pb 2 +, As 3+ ; The preset threshold is 0.05 ppb, and the sampling frequency is 5 times per second; The PLC calculates the concentration trend according to the preset algorithm and triggers regeneration 30 seconds in advance.

[0044] The automatic triggering of the regeneration switch includes the following logic: When the regeneration switch is on, the PLC closes the working column inlet valve and opens the standby column within 5 minutes; The elution stage lasts for 40 minutes, and the activation stage lasts for 60 minutes; The PLC records the saturation of the adsorbent and optimizes the timing of the next regeneration.

[0045] The specific operation in step five includes: Elution stage: dilute hydrochloric acid concentration 2.0 mol / L, countercurrent flow rate 5 m 3 / h, pressure 0.8 MPa; The waste acid liquid is separated by membrane to recover hydrochloric acid, and the recovery rate is greater than 85%; Activation stage: ultrapure water conductivity less than 0.1 μS / cm, elution to outlet pH 7.5, nitrogen blowing pressure 0.5 MPa, and final adsorbent water content less than 0.5%.

[0046] Step five also includes: The activation stage increases the adsorbent intensive treatment: inject 0.5wt% dithizone ethanol solution, soak at 45℃ for 20 minutes; Subsequently, elute with ultrapure water and blow with hot nitrogen at 60℃ for 15 minutes; The adsorbent cycle life is greater than 100 times, and the adsorption capacity attenuation after single regeneration is less than 1%.

[0047] The cycle control includes: The PLC uses a fuzzy control algorithm to dynamically adjust the adsorption column alternating period; The switching frequency is once every 24 hours, and the system double-column parallel time ratio is greater than 95%; The product electronic-grade sulfuric acid purity is greater than 99.999%, and the total amount of metal impurities is less than 0.1 ppb.

[0048] The production process also includes a pretreatment step: The raw material of electronic grade sulfuric acid is first filtered through a 0.5 μm precision filter to remove particulate impurities. After preheating to 45℃, it enters the adsorption system, and the suspended solids content is less than 1 ppb.

[0049] The waste acid liquid is treated by membrane recovery, which specifically includes: After the waste acid liquid is separated and recovered by the membrane to produce hydrochloric acid, the residual waste liquid enters the neutralization treatment unit, and calcium hydroxide is added to adjust the pH to the neutral range, so that the residual metal ions form hydroxide precipitates. After neutralization, the solution is subjected to solid-liquid separation by a plate and frame filter press, and the filtrate is returned to the pretreatment step as a rinse water source for the precision filter. The operating pressure of the plate and frame filter press is controlled in the medium-low pressure range, and the moisture content of the filter cake is controlled within the preset range.

[0050] Comparative Example 1, the difference between this comparative example and Example 1 is that in the adsorbent preparation step of this comparative example, mesoporous silica gel loaded with dithizone-phosphonic acid bifunctional groups is not used, but a monofunctional group phosphonic acid modified adsorbent is used instead. The monofunctional group phosphonic acid modified adsorbent is an adsorbent formed by modifying the surface of mesoporous silica gel with phosphonic acid groups.

[0051] Comparative Example 2, the difference between this comparative example and Example 1 is that in the system construction step of this comparative example, a double adsorption column dynamic circulation system is not established, but a single fixed bed adsorption column is used instead.

[0052] Comparative Example 3, the difference between this comparative example and Example 1 is that in the regeneration operation step of this comparative example, the adsorbent is not subjected to intensified treatment in the activation stage. Comparative Example 4, the difference between this comparative example and Example 1 is that in the pretreatment step of this comparative example, the waste acid liquid is not subjected to membrane separation and recovery and neutralization treatment.

[0053] The performance of the electronic grade sulfuric acid produced by the deep impurity removal production process in Examples 1-3 and Comparative Examples 1-4 was tested, and the test items and test methods are as follows: Metal ion removal rate test: In the constant temperature circulating adsorption system, take the feed liquid and product liquid, use inductively coupled plasma mass spectrometer, use standard addition method to determine the ion concentration change of Fe 3+ , Cu 2+ , Pb 2 +, As 3+ , etc., and calculate the total impurity removal rate.

[0054] Adsorbent cycle life test: record the number of cycles when the adsorption capacity of the adsorbent is attenuated to 80% of the initial capacity after regeneration, and measure the specific surface area change after each regeneration by nitrogen adsorption method.

[0055] System continuous operation stability test: record the unplanned downtime of the system due to regeneration switching or failure under continuous production conditions, and calculate the continuous operation rate.

[0056] Regeneration waste liquid treatment effect test: the discharge waste liquid after neutralization treatment is measured by atomic absorption spectrometry AAS to determine the residual amount of heavy metal ions, and acid-base titration method is used to measure the chemical oxygen demand COD.

[0057] The test data of examples 1-3 and comparative examples 1-4 are recorded in the following table: By comparing and analyzing the data in the table, it can be seen that the electronic grade sulfuric acid produced by the process in examples 1-3 has more excellent performance than the electronic grade sulfuric acid produced by the process in comparative examples 1-4, which shows that the dithizone-phosphonic acid bifunctional group can accurately capture metal cation impurities in electronic grade sulfuric acid through the strong coordination ability of sulfur atom with transition metal ions, and the phosphonic acid group can efficiently adsorb anion impurities through electrostatic attraction, forming a double-site synergistic adsorption mechanism; the mesoporous silica gel carrier constructs an ion sieve barrier by virtue of the nano-scale regular pore structure, blocking the entry of macromolecular organic impurities into the adsorption active site, and realizing the simultaneous deep removal of multi-component impurities from the molecular scale, improving the impurity interception capacity and adsorption selectivity; the double-adsorption column dynamic circulation system accurately maintains the ion exchange front under automatic control through hierarchical separation design; real-time monitoring of impurity concentration and intelligent triggering of regeneration program realize continuous and stable operation; the gradient countercurrent washing process is used in the regeneration stage, first desorbing impurities with dilute acid solution, then purifying the residue with ultrapure water, and finally recovering the adsorbent activity through gas blowing, forming a closed-loop regeneration control chain to avoid the risk of secondary release of impurities; the adsorbent regeneration enhanced treatment restores the damaged functional groups through in-situ repair technology, and strengthens the microporous structure combined with gas activation; the process makes the adsorbent surface form a stable self-repairing protective layer, enhancing the stability of the functional groups; combined with the waste liquid recovery technology, the extension of the service life of the adsorbent and the simplification of the regeneration waste liquid discharge are realized simultaneously, which comprehensively guarantees the environmental friendliness and economic sustainability of the production process.

[0058] By comparing and analyzing the related data in the table, it can be seen that the electronic grade sulfuric acid produced by the process of the present application not only has a high metal ion removal efficiency, but also has a long service life of the adsorbent, a stable continuous operation of the system, and an environmentally friendly treatment of waste liquid that meets the standard. Therefore, the electronic grade sulfuric acid deep decontamination production process based on dynamic circulation adsorption provided by the present application has a wider industrial application prospect and is more suitable for large-scale promotion.

[0059] While embodiments of the application have been shown and described, it is to be understood that the embodiments described are merely exemplary of the principles and application of the present application. Numerous modifications and adaptions can be effected without departing from the spirit and scope of the present application, which is not limited to the exact construction and arrangement described. It is intended, therefore, to cover all modifications and adaptions that fall within the scope of the claims and their equivalents.

Claims

1. A deep depurification process for electronic-grade sulfuric acid based on dynamic cyclic adsorption, characterized in that, Includes the following steps: Step 1: Adsorbent preparation. Mesoporous silica gel loaded with dithizone-phosphonic acid bifunctional groups is provided as the adsorbent. The pore size of the mesoporous silica gel is 10-50 nm and the specific surface area is greater than 500 m² / g. Step 2: System construction. A dual-adsorption column dynamic circulation system is established. The adsorption column is divided into a saturation zone, a mass transfer zone, and an uncontaminated zone. The electronic-grade sulfuric acid solution is continuously flowed at a constant flow rate at 30-45℃ by a programmable logic controller (PLC). Step 3: Adsorption operation. Electronic-grade sulfuric acid raw material is introduced into the dual adsorption column dynamic circulation system for adsorption treatment. At the same time, an online metal ion sensor is set at the outlet of the adsorption column to monitor the impurity concentration in real time. Step 4: Regeneration switching. When the impurity concentration detected by the online metal ion sensor reaches a preset threshold, the regeneration mode is automatically triggered. The regeneration mode includes an elution stage and an activation stage. Step 5: Regeneration operation. In the elution stage, the saturated adsorption column is countercurrently rinsed with 0.5-2.0 mol / L dilute hydrochloric acid to desorb metal ions. In the activation stage, the adsorption column is rinsed with ultrapure water until neutral and then purged with nitrogen to dry. Step Six: Cyclic Control. After regeneration, the adsorption column automatically switches back to the working sequence and runs alternately with another adsorption column to achieve continuous production.

2. The production process for deep depurification of electronic-grade sulfuric acid based on dynamic cyclic adsorption according to claim 1, characterized in that, The mesoporous silica gel is prepared by the following method: Step 1: Synthesis of mesoporous silica gel carrier I. Sol-gel method for substrate synthesis: Tetraethyl orthosilicate (TEOS) and hexadecyltrimethylammonium bromide (CTAB) were dissolved in an ethanol / water mixture at a molar ratio of 1:0.

3. Adjust the pH to 10–11, use ammonia as a catalyst, stir at 40°C for 24 hours to form a white colloid; II. Template Removal and Activation: Centrifuge to separate the solid, and calcine at 550℃ for 6 hours to remove the CTAB template; A silica carrier with a pore size of 30nm±5nm and a specific surface area of ​​750m² / g was obtained; Step 2: Loading bifunctional groups I. Preparation of bifunctional solutions: Dithizone and phosphonic acid were dissolved in anhydrous ethanol at a molar ratio of 1:1.8; Add 3-aminopropyltriethoxysilane APTES crosslinking agent, accounting for 5% of the solution mass; II. Post-processing: Wash three times with ethanol to remove physically adsorbed molecules; Vacuum dried at 90℃ for 4 hours, retaining the mesoporous structure, to obtain the mesoporous silica gel; The adsorbent is prepared by the following method: The mesoporous silica support was immersed in a bifunctional solution containing dithizone and phosphonic acid and reacted at 40-60℃ for 2-4 hours. The molar ratio of dithizone to phosphonic acid was 1:1.5-2.

0. After the reaction, filter, wash three times with ethanol, and dry under vacuum at 80-100℃ for 3-5 hours. The resulting adsorbent has a bifunctional group loading of 5-10 wt%.

3. The deep depurification process for electronic-grade sulfuric acid based on dynamic cyclic adsorption according to claim 1, characterized in that, The dual-adsorption column dynamic circulation system: The dual adsorption columns are in parallel structure, with a height-to-diameter ratio of 5:1-8:1, and are made of Hastelloy alloy. The volume ratio of the saturated zone, mass transfer zone, and uncontaminated zone is 1:2:1; The PLC controls the flow rate at 5-15 m³ / h, the temperature at 29-46℃, and the system pressure at 0.5-1.0 MPa.

4. The production process for deep depurification of electronic-grade sulfuric acid based on dynamic cyclic adsorption according to claim 1, characterized in that, Online metal ion sensors include: The online metal ion sensor is an inductively coupled plasma mass spectrometer (ICP-MS) or an atomic absorption spectrometer (AAS), and the monitored targets include Fe³⁺. + Cu² + Pb² + As³ + ; The preset threshold is 0.05 ppb, and the sampling frequency is 1-5 times / second; The PLC calculates the concentration trend based on a preset algorithm and triggers regeneration 10-30 seconds in advance.

5. The production process for deep depurification of electronic-grade sulfuric acid based on dynamic cyclic adsorption according to claim 1, characterized in that, The automatic triggering of regeneration switching includes the following logic: During regeneration switching, the PLC closes the working column inlet valve and opens the standby column within 2-5 minutes; The elution phase lasts 20-40 minutes, and the activation phase lasts 30-60 minutes. The PLC records the adsorbent saturation and optimizes the timing of the next regeneration.

6. The production process for deep depurification of electronic-grade sulfuric acid based on dynamic cyclic adsorption according to claim 1, characterized in that, Step five includes the following specific operations: Elution stage: dilute hydrochloric acid concentration 0.5-2.0 mol / L, countercurrent flow rate 2-5 m³ / h, pressure 0.3-0.8 MPa; Hydrochloric acid was recovered from waste acid liquid via membrane separation, with a recovery rate of over 85%. Activation stage: The conductivity of ultrapure water is less than 0.1 μS / cm. The adsorbent is rinsed until the outlet pH is 6.5-7.5, the nitrogen purging pressure is 0.2-0.5 MPa, and the final adsorbent moisture content is less than 0.5%.

7. The deep depurification process for electronic-grade sulfuric acid based on dynamic cyclic adsorption according to claim 1, characterized in that, Step five also includes: The activation stage is enhanced with adsorbent treatment: inject 0.1-0.5wt% dithizone ethanol solution and soak at 35-45℃ for 10-20 minutes; The subsequent steps include rinsing with ultrapure water and purging with hot nitrogen at 50-60℃ for 10-15 minutes; The adsorbent has a cycle life of more than 100 cycles, and the adsorption capacity decay is less than 1% after a single regeneration.

8. The production process for deep depurification of electronic-grade sulfuric acid based on dynamic cyclic adsorption according to claim 1, characterized in that, The loop control includes: The PLC uses a fuzzy control algorithm to dynamically adjust the alternation cycle of the adsorption columns; The switching frequency is once every 8-24 hours, and the system's dual-column parallel time accounts for more than 95%; The product's electronic-grade sulfuric acid has a purity greater than 99.999% and a total metal impurity content of less than 0.1 ppb.

9. The deep depurification process for electronic-grade sulfuric acid based on dynamic cyclic adsorption according to claim 1, characterized in that, The production process also includes a pretreatment step: Electronic-grade sulfuric acid raw materials are first filtered through a 0.1-0.5μm precision filter to remove particulate impurities; After preheating to 30-45℃, it enters the adsorption system with a suspended solids content of less than 1 ppb.

10. The production process for deep depurification of electronic-grade sulfuric acid based on dynamic cyclic adsorption according to claim 6, characterized in that, The waste acid solution is specifically treated via membrane recovery, including: The residual waste liquid generated after the waste acid is recovered by membrane separation enters the neutralization treatment unit, where calcium hydroxide is added to adjust the pH to the neutral range, so that the residual metal ions form hydroxide precipitates. After neutralization, the solution is subjected to solid-liquid separation using a plate and frame filter press, and the resulting filtrate is returned to the pretreatment step as the rinsing water source for the precision filter. The operating pressure of the plate and frame filter press is controlled in the medium and low pressure range, and the moisture content of the filter cake is controlled within a preset range.

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