A process for the resource utilization of waste acid from aluminum etching solution for display panels.

Abstract

This application relates to the field of resource recovery technology for aluminum etching solutions, specifically disclosing a process for resource recovery of waste acid from display panel aluminum etching solutions. The process includes the following steps: adsorbing the waste acid from the display panel aluminum etching solution onto mesoporous silica, filtering to obtain a three-component mixed acid solution; distilling the three-component mixed acid solution to obtain a dilute phosphoric acid solution and a two-component mixed acid solution; concentrating and purifying the dilute phosphoric acid solution to obtain 85% industrial phosphoric acid; and neutralizing the two-component mixed acid solution with calcium hydroxide and magnesium oxide to obtain CMA de-icing agent. This application effectively removes metal ions from the waste acid through mesoporous silica adsorption, improving the purity of the product.

Description

Technical Field

[0001] This application relates to the field of resource recovery technology for aluminum etching solutions, and more specifically, it relates to a resource recovery process for waste acid from aluminum etching solutions used in display panels. Background Technology

[0002] Etching waste acid is generated during the wet etching process in TFT-LCD production. The purpose of etching is to dissolve and remove the film not covered by photoresist, ultimately forming a circuit board of a specific shape. The principle of wet etching is as follows: First, metals such as aluminum, silver, and molybdenum are oxidized by nitric acid to form oxides. These oxides react with phosphoric acid to remove the oxides. Acetic acid acts as a buffer solution to stabilize the oxidizing power of nitric acid. Due to the high volatility of nitric and acetic acids, they must be continuously replenished to maintain the concentration of the etching solution until it exceeds the reference value. At this point, the entire etching solution must be completely replaced, thus generating a large amount of metal etching waste acid. Metal-containing etching waste acid is a highly acidic waste liquid from the panel manufacturing process. The main components of the waste liquid are phosphoric acid, acetic acid, nitric acid, water, and a small amount of metal ions. The mixed acid ratio is phosphoric acid (60%-75%), nitric acid (1%-5%), and acetic acid (4%-6%), which we call phosphoric acid-based etching solution. The large amount of waste liquid generated annually, if discharged without treatment, will cause significant environmental damage. Therefore, finding an economical and reasonable method to recycle phosphoric acid-based etching solution waste acid is both necessary and urgent.

[0003] In existing technologies, methods for recycling waste acid from phosphoric acid-based etching solutions mainly include neutralization, extraction, membrane separation, crystallization, and distillation. Currently, the process for purifying phosphoric acid from waste acid from phosphoric acid-based etching solutions is becoming increasingly mature. However, single-process treatment yields products with low purity, reducing their added value. Combining two or more processes can effectively address this issue. While the extraction of phosphoric acid from waste acid from phosphoric acid-based etching solutions is gradually being promoted and applied, the resource reuse technologies for the relatively small amounts of byproducts nitric acid and acetic acid are relatively limited. Expanding the reuse pathways of byproducts acetic acid and nitric acid to obtain other valuable by-products, in addition to extracting high-value phosphorus products during the production process, will be a significant research direction. For example, patent application CN101439849A discloses a comprehensive utilization process for waste aluminum etching solution. This process uses distillation to separate phosphoric acid from nitric acid and acetic acid in the waste aluminum etching solution. The distilled phosphoric acid is then filtered to remove mechanical impurities, and distilled water is added to adjust the specific gravity, yielding 85% industrial phosphoric acid. The distilled acetic acid and nitric acid mixture is placed in a stainless steel reactor, sodium hydroxide is added, and the reaction is carried out under stirring. The purified reaction solution is then concentrated, crystallized, and separated to obtain a filtrate and crystals. The crystals are dried to obtain sodium acetate. The filtrate is then concentrated, crystallized, separated, and dried to obtain sodium nitrate. Alternatively, the specific gravity of the filtrate can be concentrated to 1.2-1.3, and the process can be completed in one step using a dryer to obtain sodium nitrate. Although this method can obtain a large quantity of three industrial products—85% phosphoric acid, sodium acetate, and sodium nitrate—through recycling, it does not pre-treat and remove metal ions from the waste aluminum etching solution. These impurities will enter the final product, affecting its purity. Summary of the Invention

[0004] In order to improve the purity of acid products in waste acid from aluminum etching solution for display panels, this application provides a process for the resource utilization of waste acid from aluminum etching solution for display panels.

[0005] This application provides a process for the resource recovery of waste acid from aluminum etching solution in display panels, which adopts the following technical solution:

[0006] S1, the waste acid from the aluminum etching solution of the display panel is adsorbed by mesoporous silica and filtered to obtain a mixed acid solution containing phosphoric acid, nitric acid and acetic acid;

[0007] S2, the three-mixed acid solution is distilled to obtain dilute phosphoric acid solution and two-mixed acid solution containing nitric acid and acetic acid. The dilute phosphoric acid solution is concentrated and purified to obtain industrial phosphoric acid with a concentration of 85%.

[0008] S3, the two mixed acid solutions react with calcium hydroxide and magnesium oxide to neutralize each other, and the pH is adjusted to 7-8 to obtain a mixture of calcium magnesium acetate and calcium magnesium nitrate. The mixture is then subjected to solid-liquid separation to obtain a solid precipitate and a supernatant. The supernatant is then spray-dried, granulated, and the ratio is adjusted to obtain CMA de-icing agent.

[0009] The aluminum etching solution for the display panel includes phosphoric acid, nitric acid, acetic acid, and metal ions.

[0010] By adopting the above technical solution, firstly, the mesoporous silica adsorption in step S1 effectively removes metal ions from the waste acid, solving the problem of the impact of metal impurities on the purity of subsequent products from the source. This lays the foundation for obtaining high-purity (85%) industrial phosphoric acid in step S2 and avoids product quality problems caused by impurity residues. Secondly, in terms of product utilization, step S3 neutralizes the mixed acid solution with calcium hydroxide and magnesium oxide to generate a mixture of calcium magnesium acetate and calcium magnesium nitrate, which is further processed into CMA de-icing agent. This product is widely in demand in the field of winter road snow removal and is more environmentally friendly than traditional de-icing agents, expanding the direction of resource utilization and enhancing the economic and environmental value of the process. At the same time, the neutralization reaction uses calcium hydroxide and magnesium oxide, making the reaction process relatively mild. Furthermore, subsequent solid-liquid separation and spray drying processes enhance the stability and safety of the process, making the overall process more practical and sustainable.

[0011] Preferably, the surface of the mesoporous silica is grafted with polyethylene glycol.

[0012] Preferably, the method for preparing the mesoporous silica includes the following steps:

[0013] (1) Mesoporous silica was ultrasonically dispersed with anhydrous ethanol, then centrifuged and dried to obtain a pretreated powder;

[0014] (2) The pretreated powder was modified with an aminosilane agent to obtain aminated mesoporous silica;

[0015] (3) Aminated mesoporous silica is dispersed in N,N-dimethylformamide, and a coupling agent and carboxyl-terminated polyethylene glycol solution are added to react. After centrifugation, washing and drying, mesoporous silica grafted with polyethylene glycol with a grafting rate of 8%-12% is obtained.

[0016] By adopting the above technical solution, mesoporous silica grafted with polyethylene glycol prepared by silane coupling agent modification is used as mesoporous silica. In the resource recovery process of waste acid from aluminum etching solution for display panels, it can efficiently and selectively adsorb metal ions such as chloride ions and iron ions, significantly reducing the content of metal impurities in the etching solution. Its regular mesoporous structure and appropriate PEG grafting rate can reduce the loss of effective acids such as phosphoric acid and nitric acid while ensuring high acid permeability, thereby improving the yield and purity of 85% industrial phosphoric acid obtained by subsequent distillation and concentration. The Si-O-Si covalent bond on the material surface is stable, and it has excellent recycling performance under strong acid conditions, reducing processing costs. At the same time, it has little interference with the adsorption of nitric acid and acetic acid in the mixed acid solution, and does not affect the purity and ratio of CMA de-icing agent prepared by subsequent neutralization reaction. Thus, the overall process achieves multiple objectives of metal ion removal, efficient acid recovery, and resource utilization of by-products.

[0017] Preferably, in S1, the waste acid from the aluminum etching solution of the display panel is sequentially adsorbed by mesoporous silica and cation exchange resin, and filtered to obtain a mixed acid solution containing phosphoric acid, nitric acid and acetic acid.

[0018] By adopting the above technical solution, firstly, mesoporous silica is used as a pretreatment layer. Its porous structure is used to physically trap and remove most of the metal ions and small particulate impurities in the etching solution, reducing the processing load of the subsequent cation exchange resin. Then, the pretreated etching solution is allowed to flow through the cation exchange resin. The active groups in the resin can specifically adsorb the remaining metal ions, and deep purification is achieved through ion exchange.

[0019] Mesoporous silica achieves coarse adsorption due to its high specific surface area and rapid mass transfer efficiency, while resin achieves fine adsorption due to its high selectivity and ion exchange specificity, forming a complementary and synergistic effect. At the same time, mesoporous silica pretreatment can reduce the contamination of resin by metal ions, extend the service life of resin, reduce the regeneration frequency, and improve the overall efficiency and stability of etching solution pretreatment, laying a higher purity raw material foundation for subsequent acid separation and purification.

[0020] Preferably, the aluminum etching solution for the display panel is adsorbed by mesoporous silica and then adsorbed by cation exchange resin in a countercurrent manner.

[0021] By adopting the above technical solution, the waste acid from the aluminum etching solution for display panels is first adsorbed by mesoporous silica, which can pre-intercept suspended particles, colloidal impurities, and some organic matter and pigments in the etching solution, preventing these impurities from directly entering the subsequent cation exchange resin system and causing resin channel blockage or surface contamination. Subsequently, the etching solution is passed through the cation exchange resin in a countercurrent manner, allowing for more thorough and uniform contact between the etching solution and the resin, significantly extending the contact time and improving the resin's adsorption efficiency and saturation capacity for metal cations such as aluminum and iron ions, while reducing the risk of metal ion leakage. This combination of operations not only protects the cation exchange resin through pre-adsorption by mesoporous silica, extending its service life and reducing regeneration frequency and cost, but also enhances the metal ion removal effect through countercurrent adsorption, ultimately significantly improving the purity of the subsequent three-component mixed acid solution. This lays a high-quality raw material foundation for subsequent processes such as distillation and purification of industrial phosphoric acid and preparation of CMA de-icing agent, while also optimizing the overall process stability and economy.

[0022] Preferably, the method for preparing the cation exchange resin includes the following steps:

[0023] Step 1: Dissolve 14-18 parts by weight of polyvinyl alcohol in deionized water to obtain an aqueous phase with a concentration of 2.5%-3%; mix 100 parts by weight of styrene, 10-13 parts by weight of divinylbenzene and 30-40 parts by weight of n-heptane, then add 0.6-1 parts by weight of benzoyl peroxide and stir until homogeneous to obtain an oil phase; pour the oil phase into the aqueous phase, stir to form droplets, and heat to 65-75℃ under nitrogen protection for 5-7 hours; after the reaction is complete, cool, filter, wash with water, and dry to obtain the resin;

[0024] Step 2: Stir and disperse 300-600 parts by weight of dichloroethane and 100 parts by weight of resin, cool to freezing point, add 150-300 parts by weight of chlorosulfonic acid dropwise, controlling the temperature not to exceed 10°C, and after the addition is complete, raise the temperature to 45-55°C and react for 5-7 hours to obtain a reaction solution; quench the reaction solution, filter, and wash with water to obtain sulfonated resin.

[0025] Step 3: Sieve the sulfonated resin and soak it in hydrochloric acid solution, then wash it with water to obtain the cation exchange resin.

[0026] By adopting the above technical solution, the prepared cation exchange resin, through the synergistic design of a styrene-divinylbenzene porous framework and a high sulfonic acid group density, can efficiently adsorb and remove metallic impurity ions such as chloride ions and iron ions in the pretreatment of waste acid in display panel aluminum etching solution, significantly reducing the risk of etching defects. Its excellent acid resistance and reasonable pore structure ensure that it is not easily degraded or introduces impurities in strong acid etching solution during long-term use, and that the ion diffusion exchange kinetics are fast. At the same time, the resin can stably maintain the acidic environment of the etching solution, reducing the impact of pH fluctuations on etching uniformity, thereby improving the stability and yield of the display panel aluminum etching process.

[0027] Preferably, in step 1: 14-18 parts by weight of polyvinyl alcohol are dissolved in deionized water to obtain an aqueous phase with a concentration of 2.5%-3%; 100 parts by weight of styrene, 10-13 parts by weight of divinylbenzene, 30-40 parts by weight of n-heptane and 5-15 parts by weight of polystyrene are mixed and 0.6-1 parts by weight of benzoyl peroxide are added, and the mixture is stirred evenly to obtain an oil phase; the oil phase is poured into the aqueous phase, stirred to form droplets, and the mixture is heated and reacted for 2-3 hours under nitrogen protection, with 1-3 parts by weight of divinylbenzene added; after the reaction is completed, the mixture is cooled, filtered, washed with water, and dried to obtain the resin;

[0028] By adopting the above technical solution, an appropriate amount of polystyrene is introduced into the oil phase as a composite porogen to form a composite porogen system with n-heptane, thus constructing a richer hierarchical pore structure and accelerating the diffusion and adsorption rate of metal ions in the etching solution. At the same time, the strategy of adding divinylbenzene in steps optimizes the crosslinking degree distribution, improves the mechanical strength and structural uniformity of the resin, and makes the sulfonic acid group distribution more uniform, reducing the dead zone of exchange saturation. These improvements enable the cation exchange resin to exhibit higher adsorption efficiency, better long-term stability and more uniform ion exchange performance in the pretreatment of waste acid in aluminum etching solution for display panels.

[0029] Preferably, in step 1, the resin is further subjected to microporous etching treatment, specifically: the resin is soaked in hydrofluoric acid, washed with water, and dried to obtain porous resin.

[0030] Step 2, the sulfonated resin is further subjected to hydroxylation treatment, specifically: plasma treatment under an oxygen-containing gas atmosphere to obtain hydroxylated resin.

[0031] By adopting the above technical solution, and through the synergistic mechanism of hydrofluoric acid channel optimization, plasma surface hydroxylation, and sulfonic acid group interaction, a comprehensive improvement in the pretreatment performance of waste acid from aluminum etching solutions for display panels is achieved: hydrofluoric acid immersion effectively removes residual impurities within the resin channels and moderately enlarges the pore size, significantly reducing the diffusion resistance of metal ions; plasma treatment introduces hydroxyl groups onto the resin surface, forming synergistic adsorption sites with the existing sulfonic acid groups, improving the selectivity and capacity for metal ions such as chloride and iron ions; combined with a well-defined hydrochloric acid conversion process, it ensures that the resin is entirely in a highly active sulfonic acid form. This cation adsorption resin exhibits superior performance in terms of efficient impurity removal, deep purification of etching solutions, and long-term operational stability.

[0032] Preferably, a phosphonation treatment is included between step 2 and step 3, specifically: 100 parts by weight of sulfonated resin and 300-600 parts by weight of dichloroethane are stirred and dispersed, 50-100 parts by weight of phosphorous acid and 30-80 parts by weight of phosphoric acid are added to react and obtain the product, and the product is quenched, filtered, washed with water and dried to obtain phosphoric acid resin.

[0033] By employing the above technical solution and introducing the cation exchange resin obtained through the phosphonation step, a multi-component synergistic adsorption system of sulfonic acid groups, phosphonic acid groups, and hydroxyl groups is simultaneously constructed on a styrene-divinylbenzene porous framework, significantly improving the removal capacity and selectivity of metal impurities in aluminum etching solutions for display panels. The sulfonic acid groups provide rapid and high-capacity ion exchange, the phosphonic acid groups enhance the chelation effect on high-valence metal ions such as chloride and iron ions, and the hydroxyl groups improve hydrophilicity and mass transfer efficiency. This resin exhibits excellent stability and anti-swelling ability in strongly acidic etching solutions, effectively reducing metal ion concentration. Its hierarchical porous structure and uniform distribution of functional groups ensure processing efficiency and regeneration performance during long-term continuous operation.

[0034] In summary, this application has at least one of the following beneficial technical effects:

[0035] 1. This application achieves effective adsorption of metal ions in the aluminum etching solution of the display panel through mesoporous silica, which solves the problem of the impact of metal impurities on the purity of subsequent products from the source and improves the purity of the obtained products.

[0036] 2. The mesoporous silica of this application is mesoporous silica with polyethylene glycol grafted on its surface. With the ample adsorption sites provided by the ordered channels and high specific surface area of ​​the mesoporous silica, combined with the strong complexing ability of polyethylene glycol ether oxygen atoms to metal ions such as chloride ions and iron ions, it can efficiently and selectively remove metal ions in the etching solution.

[0037] 3. This application uses a combination of mesoporous silica and cation exchange resin to pretreat the aluminum etching solution of the display panel. The mesoporous silica achieves coarse adsorption due to its high specific surface area and fast mass transfer efficiency, while the resin achieves fine adsorption due to its high selectivity and ion exchange specificity, forming a complementary and synergistic effect. At the same time, the mesoporous silica pretreatment can reduce the contamination of the resin by metal ions, laying a higher purity raw material foundation for subsequent acid separation and purification.

[0038] 4. The cation exchange resin prepared in this application, through the synergistic design of a styrene-divinylbenzene porous framework and a high sulfonic acid group density, can efficiently adsorb and remove metal impurity ions such as chloride ions and iron ions in the pretreatment of waste acid from aluminum etching solution for display panels, thereby improving product purity. Detailed Implementation

[0039] The present application will be further described in detail below with reference to preparation examples and embodiments. Unless otherwise specified, the raw materials involved in the preparation examples and embodiments are commercially available.

[0040] Preparation Examples 1-3: Mesoporous Silica

[0041] Preparation Example 1

[0042] This preparation example discloses a method for preparing mesoporous silica, specifically including the following steps:

[0043] 10g of mesoporous silica powder was ultrasonically dispersed in 500mL of anhydrous ethanol at 250W for 30min. After centrifugation at 8000rpm for 10min, the precipitate was collected and placed in a vacuum drying oven and dried at 60℃ for 12h to obtain pretreated powder.

[0044] Take 6g of pretreated powder, add 200mL of anhydrous toluene (dehydrated by molecular sieve), ultrasonically disperse for 20min, add 0.8g of 3-aminopropyltriethoxysilane, heat to 80℃ under nitrogen protection, and magnetically stir for 5h; after the reaction is completed, centrifuge at 8000rpm for 10min, collect the solid, wash 3 times with anhydrous toluene, and vacuum dry at 60℃ for 6h to obtain aminated mesoporous silica;

[0045] 3g of carboxyl-terminated polyethylene glycol (MTO) with a molecular weight of 3000 was dissolved in 75mL of anhydrous DMF (dehydrated via molecular sieve), and the solution was magnetically stirred for 10min until completely dissolved to obtain a carboxyl-terminated polyethylene glycol solution. In a nitrogen-protected three-necked flask, 6g of aminated mesoporous silica and 200mL of anhydrous DMF were added, followed by 0.7g of 1-ethyl-(3-dimethylaminopropyl)carbodiimide hydrochloride and 0.4g of... N-hydroxysuccinimide was activated by magnetic stirring for 20 min, and then a carboxyl-terminated polyethylene glycol solution was added dropwise at 1 drop / s. After the addition was complete, the pH of the system was adjusted to 6, and the temperature was raised to 40℃ under nitrogen protection and stirred for 5 h. After the reaction was completed, the mixture was cooled to room temperature, centrifuged at 10000 rpm for 15 min, the solid was collected, and ultrasonically washed 5 times with anhydrous ethanol (10 min each time), and then washed once with 5% dilute nitric acid. The solid was then vacuum dried at 60℃ to constant weight to obtain mesoporous silica with polyethylene glycol grafted on the surface, and the grafting rate was 8%.

[0046] Preparation Example 2

[0047] This preparation example discloses a method for preparing mesoporous silica, specifically including the following steps:

[0048] 10g of mesoporous silica powder was ultrasonically dispersed in 500mL of anhydrous ethanol at 250W for 30min. After centrifugation at 8000rpm for 10min, the precipitate was collected and placed in a vacuum drying oven and dried at 60℃ for 12h to obtain pretreated powder.

[0049] Take 6g of pretreated powder, add 200mL of anhydrous toluene (dehydrated by molecular sieve), ultrasonically disperse for 20min, add 1.2g of 3-aminopropyltriethoxysilane, heat to 80℃ under nitrogen protection, and magnetically stir for 6h; after the reaction is completed, centrifuge at 8000rpm for 10min, collect the solid, wash 3 times with anhydrous toluene, and vacuum dry at 60℃ for 6h to obtain aminated mesoporous silica;

[0050] 5g of carboxyl-terminated polyethylene glycol with a molecular weight of 3000 was dissolved in 125mL of anhydrous DMF (dehydrated by molecular sieve), and the solution was magnetically stirred for 10min until completely dissolved to obtain a carboxyl-terminated polyethylene glycol solution. In a nitrogen-protected three-necked flask, 6g of aminated mesoporous silica and 200mL of anhydrous DMF were added, followed by the sequential addition of 1.0g of 1-ethyl-(3-dimethylaminopropyl)carbodiimide hydrochloride and 0.6g of... N-hydroxysuccinimide was activated by magnetic stirring for 20 min, and then a carboxyl-terminated polyethylene glycol solution was added dropwise at 1 drop / s. After the addition was complete, the pH of the system was adjusted to 6, and the temperature was raised to 40℃ under nitrogen protection and stirred for 6 h. After the reaction was completed, the mixture was cooled to room temperature, centrifuged at 10000 rpm for 15 min, the solid was collected, and ultrasonically washed 5 times with anhydrous ethanol (10 min each time), and then washed once with 5% dilute nitric acid. The solid was then vacuum dried at 60℃ to constant weight to obtain mesoporous silica with polyethylene glycol grafted on the surface, and the grafting rate was 10%.

[0051] Preparation Example 3

[0052] This preparation example discloses a method for preparing mesoporous silica, specifically including the following steps:

[0053] 10g of mesoporous silica powder was ultrasonically dispersed in 500mL of anhydrous ethanol at 250W for 30min. After centrifugation at 8000rpm for 10min, the precipitate was collected and placed in a vacuum drying oven and dried at 60℃ for 12h to obtain pretreated powder.

[0054] Take 6g of pretreated powder, add 200mL of anhydrous toluene (dehydrated by molecular sieve), sonicate for 20min, add 1.6g of 3-aminopropyltriethoxysilane, heat to 80℃ under nitrogen protection, and magnetically stir for 7h. After the reaction is completed, centrifuge at 8000rpm for 10min, collect the solid, wash 3 times with anhydrous toluene, and vacuum dry at 60℃ for 6h to obtain aminated mesoporous silica.

[0055] 7g of carboxyl-terminated polyethylene glycol with a molecular weight of 3000 was dissolved in 176mL of anhydrous DMF (dehydrated by molecular sieve), and the solution was magnetically stirred for 10min until completely dissolved to obtain a carboxyl-terminated polyethylene glycol solution. In a nitrogen-protected three-necked flask, 6g of aminated mesoporous silica and 200mL of anhydrous DMF were added, followed by 1.3g of 1-ethyl-(3-dimethylaminopropyl)carbodiimide hydrochloride and 0.8g of... N-hydroxysuccinimide was activated by magnetic stirring for 20 min, and then a carboxyl-terminated polyethylene glycol solution was added dropwise at 1 drop / s. After the addition was complete, the pH of the system was adjusted to 6, and the temperature was raised to 40℃ under nitrogen protection, and the reaction was stirred for 6 h. After the reaction was completed, the mixture was cooled to room temperature, centrifuged at 10000 rpm for 15 min, the solid was collected, and ultrasonically washed 5 times with anhydrous ethanol (10 min each time), and then washed once with 5% dilute nitric acid. The solid was then vacuum dried at 60℃ to constant weight to obtain mesoporous silica with polyethylene glycol grafted on the surface, and the grafting rate was 12%.

[0056] Preparation Examples 4-7: Cationic Adsorption Resins

[0057] Preparation Example 4

[0058] This preparation example discloses a method for preparing a cation adsorption resin, specifically including the following steps:

[0059] Step 1: Add 16g of polyvinyl alcohol to 553mL of deionized water and stir magnetically at 60℃ for 30min until completely dissolved. Cool to room temperature to obtain the aqueous phase. Mix 100g of styrene, 12g of divinylbenzene, and 35g of n-heptane evenly, then add 0.8g of benzoyl peroxide. Stir magnetically at 25℃ for 15min until dissolved to obtain the oil phase. Slowly pour the oil phase into the aqueous phase and stir at 300rpm for 10min to form uniform droplets. Replace the air with nitrogen gas at a flow rate of 20sccm for 15min. Raise the temperature to 70℃, maintain the stirring speed at 200rpm, and react under nitrogen protection for 6h. After the reaction is complete, cool naturally to room temperature, filter and collect the resin particles, wash with deionized water at 200W power three times (10min each time), and vacuum dry at 50℃ for 12h to obtain the resin matrix.

[0060] Step 2: Add 450g of dichloroethane to a three-necked flask and add 100g of resin matrix. Stir at 300rpm for 30min until completely dispersed. Place the flask in an ice-salt bath to cool to -2℃. Under magnetic stirring, add 225g of chlorosulfonic acid dropwise through a constant pressure dropping funnel at a dropping rate of 1 drop / s, controlling the reaction temperature to not exceed 10℃. After the addition is complete, remove the ice bath and raise the temperature to 50℃ at a rate of 1℃ / min. Maintain this temperature for 6h. After the reaction is complete, slowly pour the reaction solution into 500g of ice water to quench it and stir for 30min. Collect the sulfonated resin by filtration and wash it with deionized water 4 times (15min each time) until the pH of the filtrate is 3 to obtain the sulfonated resin.

[0061] The sulfonated resin was sieved using a standard sieve to select particles with a diameter of 0.3-1.2 mm. Then, 5% hydrochloric acid solution (solid-liquid ratio 1:10) was added, and the mixture was soaked at 25°C for 24 hours (stirred 3 times during the process). After filtration, the filtrate was washed with deionized water until the pH of the filtrate was 6. The filtrate was then vacuum dried at 50°C to constant weight to obtain a cation exchange resin with an exchange capacity of 4.7 meq / g.

[0062] Preparation Example 5

[0063] This preparation example is basically the same as Preparation Example 4, except that in step (1): 16g of polyvinyl alcohol is added to 553mL of deionized water and magnetically stirred at 60℃ for 30min until completely dissolved. The mixture is then cooled to room temperature to obtain an aqueous phase. 100g of styrene, 12g of divinylbenzene, 35g of n-heptane and 10g of polystyrene are mixed evenly and 0.8g of benzoyl peroxide is added. The mixture is magnetically stirred at 25℃ for 15min until dissolved to obtain an oil phase. The oil phase is slowly poured into the aqueous phase and stirred at 350rpm for 10min to form uniform droplets. The air is replaced by nitrogen gas at a flow rate of 20sccm for 15min. The temperature is raised to 70℃, and the stirring speed is maintained at 200rpm. The mixture is reacted under nitrogen protection for 2.5h. Then 2g of divinylbenzene is added and the reaction continues for 3.5h. After the reaction is completed, the mixture is naturally cooled to room temperature. The resin particles are collected by filtration and ultrasonically washed three times (10min each time) with deionized water at 200W power. The mixture is then vacuum dried at 50℃ for 12h to obtain the resin matrix.

[0064] This preparation example ultimately yielded a cation exchange resin with an exchange capacity of 5.1 meq / g.

[0065] Preparation Example 6

[0066] This preparation example is basically the same as preparation example 5, except that the resin matrix obtained in step (1) is placed in a 5% hydrofluoric acid solution (solid-liquid ratio 1:10), stirred and soaked at room temperature for 30 min, filtered, washed with deionized water until the pH of the filtrate is 7, and vacuum dried at 50°C to constant weight to obtain porous resin.

[0067] The sulfonated resin obtained in step (2) is placed in the plasma reaction chamber, the chamber is closed and evacuated to 30 Pa, oxygen is introduced until the chamber pressure stabilizes at 30 Pa, the power is set to 100 W, and the treatment is carried out for 15 min. After the treatment is completed, the resin is naturally cooled to room temperature and then removed to obtain hydroxylated resin.

[0068] This preparation example ultimately yielded a cation exchange resin with an exchange capacity of 5.3 meq / g.

[0069] Preparation Example 7

[0070] This preparation example is basically the same as Preparation Example 5, except that steps (2) and (3) also include phosphonation treatment, specifically: 100g of dry sulfonated resin and 450g of dichloroethane are added to a three-necked flask equipped with a mechanical stirrer, thermometer and reflux condenser. The mixture is stirred at room temperature for 30 min, then 75g of phosphorous acid is added and stirred for 15 min. Then 55g of phosphorus trichloride is added in batches with a 10 min interval between each batch. The temperature is raised to 80℃ and the mixture is kept under reflux for 6 h while stirring. After the reaction is completed, the reaction solution is poured into 500g of ice water while stirring, and quenched for 1 h. The resin particles are collected by filtration, washed three times with deionized water, then neutralized with 5% sodium carbonate solution until the pH of the filtrate is 6, and finally washed with deionized water until there are no chloride ions in the filtrate to obtain phosphonated resin.

[0071] This preparation example ultimately yielded a cation exchange resin with an exchange capacity of 5.9 meq / g.

[0072] Example 1

[0073] This embodiment discloses a process for the resource utilization of waste acid from aluminum etching solution in display panels, specifically including the following steps:

[0074] S1, the waste acid solution from the aluminum etching process of the display panel is subjected to a plate and frame filter press (filter cloth pore size 5μm) to remove the suspension, and after treatment at a feed pressure of 0.3MPa, a pretreated solution is obtained; mesoporous silica particles and binder are molded and filled into a PP column, and the pretreated solution is passed through the column from top to bottom at a flow rate of 2Bv / h to obtain a mixed acid solution containing phosphoric acid, nitric acid and acetic acid; the main components of the waste acid solution from the aluminum etching process of the display panel are: phosphoric acid content of 15%, nitric acid content of 5%, acetic acid content of 6.5%, aluminum ion content of 0.8% and deionized water of 76.51%; and the mesoporous silica particles are commercially available products;

[0075] S2, under a pressure of -0.095 MPa, the three-component acid solution is distilled at 120°C, and the distillate is condensed and absorbed by deionized water to obtain a two-component acid solution containing nitric acid and acetic acid. Then, the temperature is raised to 140°C to obtain a phosphoric acid product, and its mass percentage concentration is adjusted to 85% by adding deionized water to the phosphoric acid product.

[0076] S3, add an alkali source (calcium hydroxide: magnesium oxide molar ratio = 1:1.5) at 1.05 times the total molar amount of acetic acid and nitric acid in the mixed acid solution. Specifically: heat the mixed acid solution to 40℃, then add the mixture of magnesium hydroxide and magnesium oxide in three portions (each 15 min apart), stirring at 80 r / min. After reacting for 30 min, check the pH. If it is not 7-8, add 0.1 mol / L calcium hydroxide solution to adjust until the pH is 7-8. The reaction solution is first allowed to settle statically at room temperature for 2 h, and the supernatant is centrifuged. The solid precipitate is then separated. The supernatant was filtered through a 0.22μm filter and concentrated by reverse osmosis to a solid content of 50%. It was then passed through a centrifugal spray drying tower at a feed rate of 500 kg / h, an inlet air temperature of 180℃, an outlet air temperature of 100℃, and a rotation speed of 15000 r / min to obtain dried powder. A 5% starch solution was sprayed onto the dried powder using a disc granulator at a granulation speed of 12 r / min to obtain particles with a diameter of 2-4 mm. Calcium acetate was added to the particles and mixed thoroughly to obtain CMA de-icing agent, with a calcium ion to magnesium ion molar ratio of 1:1.

[0077] Example 2

[0078] This embodiment is basically the same as that of Example 1, except that: in S1, the mesoporous silica is the one obtained in Preparation Example 1.

[0079] Example 3

[0080] This embodiment is basically the same as that of Example 1, except that: in S1, the mesoporous silica is the one obtained in Preparation Example 2.

[0081] Example 4

[0082] This embodiment is basically the same as that of Example 1, except that: in S1, the mesoporous silica is the one obtained in Preparation Example 3.

[0083] Example 5

[0084] This embodiment is basically the same as Embodiment 1, except that: S1, the waste acid liquid of the display panel aluminum etching solution is subjected to a plate and frame filter press (filter cloth pore size 5μm) to remove the suspension, and the feed pressure is 0.3MPa to obtain a pretreated liquid; mesoporous silica particles and binder are molded and filled into a PP column, and the pretreated liquid flows from top to bottom through the column at a flow rate of 2Bv / h, and then flows countercurrently through a cation adsorption resin to obtain a mixed acid liquid containing phosphoric acid, nitric acid and acetic acid; wherein the main components of the waste acid liquid of the display panel aluminum etching solution are: phosphoric acid content of 15%, nitric acid content of 5%, acetic acid content of 6.5%, aluminum ion content of 0.8% and deionized water of 76.51%; and the mesoporous silica particles are obtained from Preparation Example 2, and the cation adsorbent is obtained from Preparation Example 4;

[0085] Example 6

[0086] This embodiment is basically the same as Example 1, except that in S1, the cationic adsorbent is the one obtained in Preparation Example 5.

[0087] Example 7

[0088] This embodiment is basically the same as Example 1, except that in S1, the cationic adsorbent is the one obtained in Preparation Example 6.

[0089] Example 8

[0090] This embodiment is basically the same as Example 1, except that in S1, the cationic adsorbent is the one obtained in Preparation Example 7.

[0091] Comparative Example 1

[0092] This comparative example discloses a process for the resource utilization of waste acid from aluminum etching solution in display panels, which specifically includes the following steps:

[0093] S1, under a pressure of -0.095 MPa, the three-component acid solution is distilled at 120°C, and the distillate is condensed and absorbed by deionized water to obtain a two-component acid solution containing nitric acid and acetic acid. Then, the temperature is raised to 140°C to obtain a phosphoric acid product, and its mass percentage concentration is adjusted to 85% by adding deionized water to the phosphoric acid product.

[0094] S2, add an alkali source (calcium hydroxide: magnesium oxide molar ratio = 1:1.5) at 1.05 times the total molar amount of acetic acid and nitric acid in the mixed acid solution. Specifically: heat the mixed acid solution to 40℃, then add the mixture of magnesium hydroxide and magnesium oxide in three portions (each 15 min apart), stirring at 80 r / min. After reacting for 30 min, check the pH. If it is not 7-8, add 0.1 mol / L calcium hydroxide solution to adjust until the pH is 7-8. The reaction solution is first allowed to settle statically at room temperature for 2 h, and the supernatant is centrifuged. The solid precipitate is then separated. The supernatant was filtered through a 0.22μm filter and concentrated by reverse osmosis to a solid content of 50%. It was then passed through a centrifugal spray drying tower at a feed rate of 500 kg / h, an inlet air temperature of 180℃, an outlet air temperature of 100℃, and a rotation speed of 15000 r / min to obtain dried powder. A 5% starch solution was sprayed onto the dried powder using a disc granulator at a granulation speed of 12 r / min to obtain particles with a diameter of 2-4 mm. Calcium acetate was added to the particles and mixed thoroughly to obtain CMA de-icing agent, with a calcium ion to magnesium ion molar ratio of 1:1.

[0095] Performance testing

[0096] Based on ICP-OES, the Al in phosphoric acid products 3+Metal impurities were detected, and the removal rate (%) was calculated as (C0 - C) / C0 × 100%, where C0 is the Al content of Comparative Example 1. 3+ Concentration, C represents Al in each embodiment 3+ The concentration and test results are recorded in Table 1.

[0097] Table 1 Performance test data of Examples 1-8 and Comparative Example 1

[0098]

[0099] Referring to Table 1, and in conjunction with Example 1 and Comparative Example 1, it can be seen that although distillation alone can remove most of the Al... 3+ (Reduced from 8000ppm to 128.6ppm), but significant residues remain; while after pretreatment with mesoporous silica, Al 3+ The concentration was further reduced to 28.4 ppm, with a removal rate of 77.9%, fully demonstrating that this application can effectively reduce the content of metal impurities from the source and improve the purity of subsequent products through mesoporous silica. This effect is due to the high specific surface area, ordered channels, and strong complexing ability of surface functional groups of mesoporous silica with metal ions, providing a higher purity raw material basis for subsequent distillation and separation, reflecting the synergistic effect of pretreatment and distillation. It also lays the foundation for further series connection with cation exchange resin to achieve coarse adsorption + fine adsorption, significantly improving the efficiency and stability of the entire waste acid resource utilization process.

[0100] Referring to Table 1 and in conjunction with Examples 1 and 2, it can be seen that when commercially available mesoporous silica is used for pretreatment, the Al content in the phosphoric acid product is reduced. 3+ The concentration decreased from 128.6 ppm by direct distillation to 28.4 ppm, achieving a removal rate of 77.9%; while using mesoporous silica grafted with polyethylene glycol, Al... 3+ The concentration was further reduced to 15.7 ppm, and the removal rate increased to 87.8%, indicating that the mesoporous silica grafted with polyethylene glycol significantly enhanced the selective adsorption effect on iron ions due to its ordered channels, high specific surface area, and strong complexing ability of ether oxygen atoms for metal ions. This can more effectively reduce the content of metal impurities from the source, providing a higher purity raw material basis for subsequent distillation and separation. This demonstrates the positive role of material modification in improving the efficiency of waste acid treatment and the purity of the product.

[0101] Referring to Table 1 and in conjunction with Examples 3 and 5, it can be seen that using mesoporous silica grafted with polyethylene glycol alone can reduce the Al content in phosphoric acid products. 3+ The concentration was reduced to 12.3 ppm, with a removal rate of 90.4%; and after treatment with this mesoporous silica and cation exchange resin in series, Al 3+The concentration was further reduced to 6.8 ppm, and the removal rate increased to 94.7%, which fully demonstrates that the present application significantly improved the metal ion removal efficiency and product purity through the synergistic effect of mesoporous silica and cation exchange resin. The results also show that mesoporous silica pretreatment can effectively reduce the contamination of the resin by metal ions, laying a high-purity raw material foundation for subsequent refining, and improving the overall efficiency and stability of the etching solution resource utilization process.

[0102] This specific embodiment is merely an explanation of this application and is not intended to limit it. After reading this specification, those skilled in the art can make modifications to this embodiment without contributing any inventive step, but such modifications are protected by patent law as long as they fall within the scope of the claims of this application.

Claims

1. A display panel aluminum etching solution waste acid resource treatment process, characterized in that: The method comprises the following steps: S1, the display panel aluminum etching liquid waste acid is sequentially adsorbed by mesoporous silica and cation exchange resin, and a three-mixed acid liquid containing phosphoric acid, nitric acid and acetic acid is obtained by filtration; S2, the three-mixed acid liquid is distilled to obtain a dilute phosphoric acid liquid and a two-mixed acid liquid containing nitric acid and acetic acid, and the dilute phosphoric acid liquid is concentrated and purified to obtain industrial phosphoric acid with a concentration of 85%; S3, the two-mixed acid liquid is subjected to neutralization reaction with calcium hydroxide and magnesium oxide, the pH is adjusted to 7-8, a calcium-magnesium acetate and calcium-magnesium nitrate mixed liquid is obtained, solid-liquid separation is performed on the mixed liquid to obtain a solid precipitate and a supernatant, and the supernatant is subjected to spray drying, granulation and proportioning to obtain a CMA snow melting agent; The display panel aluminum etching liquid comprises phosphoric acid, nitric acid, acetic acid and metal ions; The mesoporous silica is grafted with polyethylene glycol on the surface; The preparation method of the cation exchange resin comprises the following steps: Step 1: 14-18 parts by weight of polyvinyl alcohol is dissolved in deionized water to obtain a water phase with a concentration of 2.5%-3%; 100 parts by weight of styrene, 10-13 parts by weight of divinylbenzene, 30-40 parts by weight of n-heptane and 5-15 parts by weight of polystyrene are mixed, and then 0.6-1 part by weight of benzoyl peroxide is added and stirred uniformly to obtain an oil phase; the oil phase is poured into the water phase, and stirring is performed to form liquid droplets; under nitrogen protection, the temperature is raised for 2-3 hours, and 1-3 parts by weight of divinylbenzene is added; after the reaction is completed, cooling, filtration, water washing and drying are performed to obtain the resin; the resin is soaked in hydrofluoric acid, and then water washing and drying are performed to obtain a porous resin; Step 2: 300-600 parts by weight of dichloroethane is stirred and dispersed with 100 parts by weight of the porous resin, the temperature is lowered to the freezing point, 150-300 parts by weight of chlorosulfonic acid is added dropwise, the temperature is controlled to be not higher than 10 DEG C, after the dropwise addition is completed, the temperature is raised to 45-55 DEG C, and the reaction is performed for 5-7 hours to obtain a reaction liquid; the reaction liquid is quenched, filtered and washed with water to obtain a sulfonated resin; the sulfonated resin is subjected to plasma treatment in an oxygen-containing gas atmosphere to obtain a hydroxylated resin; Step 3: the hydroxylated resin is sieved and soaked in a hydrochloric acid solution, and then water washing is performed to obtain the cation exchange resin.

2. The display panel aluminum etching solution waste acid resource treatment process according to claim 1, characterized in that: The preparation method of the mesoporous silica comprises the following steps: (1) the mesoporous silica is ultrasonically dispersed in anhydrous ethanol, centrifuged and dried to obtain a pretreated powder; (2) the pretreated powder is modified by an amino silane agent to obtain amino-functionalized mesoporous silica; (3) the amino-functionalized mesoporous silica is dispersed in N,N-dimethylformamide, a coupling agent and a carboxyl-terminated polyethylene glycol solution are added and reacted, centrifuged, washed and dried to obtain mesoporous silica grafted with polyethylene glycol with a grafting rate of 8%-12%. 3.The display panel aluminum etching solution waste acid resource treatment process of claim 1, characterized in that: The display panel aluminum etching liquid waste acid is adsorbed by the mesoporous silica and then adsorbed by the cation exchange resin in a countercurrent manner.

4. The display panel aluminum etching solution waste acid resource treatment process according to claim 1, characterized in that: Between step 2 and step 3, phosphonation treatment is further included, specifically: 100 parts by weight of the sulfonated resin is stirred and dispersed with 300-600 parts by weight of dichloroethane, 50-100 parts by weight of phosphorous acid and 30-80 parts by weight of phosphorus trichloride are added and reacted to obtain a product, the product is quenched, filtered, washed with water and dried to obtain a phosphated resin.

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