Method for purifying and recovering hydrofluoric acid waste liquid in electronic industry

Abstract

Disclosed in the present invention is a method for purifying and recovering hydrofluoric acid waste liquid in the electronic industry, the method comprising: first rectifying hydrofluoric acid waste liquid to remove moisture, then performing membrane separation treatment on the feed liquid to remove most of metal ions in the feed liquid, then performing adsorption treatment on the feed liquid to remove a small amount of metal ions in the feed liquid, and finally performing membrane separation treatment to remove trace metal ions and particulate impurities in the feed liquid. The present invention effectively removes impurities and metal ions in hydrofluoric acid waste liquid in the electronic industry by means of a specific combination process, and the product meets the electronic grade reuse standard, thereby improving the resource recycling rate.

Description

A method for purifying and recovering hydrofluoric acid waste liquid in the electronics industry Background Technology

[0001] In the electronics industry, hydrofluoric acid (HF) is a crucial cleaning agent widely used in the cleaning processes of semiconductor manufacturing and integrated circuits. However, the waste hydrofluoric acid solution after use contains a large amount of water, a small amount of hydrofluoric acid, particulate impurities, and metal ions. These impurities severely affect the reuse value and safety of hydrofluoric acid. Therefore, developing effective purification and recycling methods for waste hydrofluoric acid is of great significance for resource recycling and environmental protection.

[0002] Existing hydrofluoric acid purification and recovery technologies mainly include chemical precipitation, ion exchange, and distillation. Chemical precipitation converts impurities in the solution into insoluble solids by adding a precipitant, which are then separated by filtration. However, this method generates large amounts of fluoride-containing sludge with complex composition, low quality, and inability to be recycled, and it also poses secondary pollution problems. Ion exchange utilizes ion exchange resins to adsorb impurity ions in the solution, but resin regeneration and treatment costs are high, and its efficiency is limited when treating high-concentration waste liquids. Distillation evaporates hydrofluoric acid by heating, and then collects the purified hydrofluoric acid by condensation. However, the high temperatures during distillation can corrode equipment, and it consumes a lot of energy.

[0003] While existing technologies can purify hydrofluoric acid to some extent, they still have limitations, such as low purification efficiency, high cost, equipment corrosion problems, and the inability to effectively remove specific types of impurities. Particularly in the electronics industry, the purity requirements for hydrofluoric acid are extremely high, and existing purification technologies often fail to meet the reuse standards for electronic-grade hydrofluoric acid. Therefore, there is an urgent need to develop more efficient and environmentally friendly technologies for recycling hydrofluoric acid waste liquid, reducing environmental pollution, lowering production costs, and improving resource recycling rates. Technical issues

[0004] Type the technical issue description paragraph here. Technical solutions

[0005] The purpose of this invention is to provide an innovative method for purifying and recycling hydrofluoric acid wastewater in the electronics industry. This invention, through a series of optimized process steps and purification methods, effectively removes moisture, impurities, and metal ions from hydrofluoric acid wastewater, improving the purity of the hydrofluoric acid to meet electronic-grade reuse standards, while simultaneously reducing energy consumption and the risk of equipment corrosion, and increasing resource recycling rates.

[0006] To achieve the above objectives, the present invention adopts the following technical solution:

[0007] A method for purifying and recovering hydrofluoric acid waste liquid in the electronics industry includes the following steps:

[0008] (1) The hydrofluoric acid waste liquid is fed into a distillation column, and nitrogen is introduced into the distillation column for distillation treatment. The top temperature of the distillation column is 60℃~100℃, the bottom temperature is 70℃~110℃, and the operating pressure is controlled at 0.02~0.1Mpa. The inner wall of the distillation column has an anti-corrosion layer.

[0009] (2) The side stream fraction of the distillation column is fed into the first membrane separation system for membrane separation treatment. The membrane material of the first membrane separation system is an acid-resistant membrane.

[0010] (3) The permeate obtained from the first membrane separation system is sent to the adsorption tower for adsorption treatment to remove some of the metal ions in the feed liquid; the inner wall of the adsorption tower is provided with an anti-corrosion material layer.

[0011] (4) The feed liquid treated by the adsorption tower is sent to the second membrane separation system for membrane separation treatment. The membrane material of the second membrane separation system is an acid-resistant demetallization membrane. The trace metal ions and particulate impurities in the feed liquid are recovered as electronic-grade hydrofluoric acid on the permeate side of the second membrane separation system.

[0012] Preferably, the reflux ratio of the distillation column in step (1) is 0.1 to 1.

[0013] Preferably, the nitrogen charging rate in step (1) is 0.1~1 Nm. 3 / h.

[0014] Preferably, the anti-corrosion layer in step (1) is a polytetrafluoroethylene (PTFE) layer or a PFA layer.

[0015] Preferably, step (1) further includes the step of removing water from the top of the distillation column.

[0016] Preferably, the acid-resistant membrane described in step (2) is a composite membrane material of one or more of polyamide (PA), polysulfonamide (PSA), or polyethyleneimine (PEI). The acid-resistant membrane can be prepared by any of the following methods: interfacial polymerization, phase inversion, or surface modification.

[0017] Preferably, the first membrane separation system in step (2) includes multiple sets of acid-resistant membrane modules connected in series or in parallel, wherein the liner of the acid-resistant membrane module is PFA or polytetrafluoroethylene (PTFE) resin.

[0018] Preferably, the anti-corrosion material layer in step (3) is PTFE or PFA.

[0019] Preferably, the adsorption tower in step (3) is filled with an acid-resistant chelating resin as an adsorbent, and the filling height of the adsorbent accounts for 1 / 3 to 1 / 2 of the height of the adsorption tower.

[0020] Preferably, the acid-resistant chelating resin is a PHA chelating resin.

[0021] More preferably, the PHA chelating resin is prepared by the following method:

[0022] (1-1) Sodium persulfate was added as a thermal initiator to an aqueous solution of acrylamide and N,N-methylene-bisacrylamide mixture, and the mixture was heated in a water bath at 60°C for 15-30 min to initiate the polymerization reaction and obtain the polymer.

[0023] (1-2) The polymer is placed in a hydroxylamine hydrochloride solution for 30 min to form hydroxamic acid groups; then the pH is adjusted to 12 with sodium hydroxide solution, the mixture is left overnight and neutralized with acid, and then washed to obtain the PHA chelating resin.

[0024] Preferably, the mass ratio of acrylamide to N,N-methylene-bisacrylamide is 5:1.

[0025] Preferably, the PHA chelating resin undergoes pretreatment before use, the pretreatment including:

[0026] The PHA chelating resin was soaked in water for 1 to 1.5 hours, and then washed 3 to 5 times with 4% to 6% wt H2SO4, water, and 4% to 6% wt NaOH alternately. Finally, it was washed with water until neutral.

[0027] Preferably, the second membrane separation system described in step (4) includes multiple sets of acid-resistant metal ion removal membrane modules connected in series or parallel, wherein the membrane material of the acid-resistant metal ion removal membrane modules is perfluorinated PMMD-CTFE membrane material. This can further remove trace metal ions and particulate impurities from hydrofluoric acid waste liquid.

[0028] The perfluorinated PMMD-CTFE membrane material is prepared by the following method:

[0029] (2-1) Preparation of copolymer A:

[0030] Perfluoro-2-methylene-4-methyl-1,3-dioxolane (PMMD) and trifluorochloroethylene (CTFE) were mixed in a perfluoro solvent and polymerized under the action of a catalyst to obtain copolymer A.

[0031] (2-2) Preparation of acid-resistant composite membrane:

[0032] The copolymer A and acetone are mixed in a perfluorinated solvent at 60-80°C to obtain a composite film liquid. The composite film liquid is then coated on the surface of a polytetrafluoroethylene film and dried to obtain the acid-resistant composite film.

[0033] Preferably, the perfluorinated solvent is selected from one or more of Fluorinert FC-40, Fluorinert FC-72 or Fluorinert FC-75.

[0034] Preferably, the mass ratio of perfluoro-2-methylene-4-methyl-1,3-dioxolane to trifluorochloroethylene in step (2-1) is 1:5~7.

[0035] Preferably, in step (2-1), the total mass concentration of perfluoro-2-methylene-4-methyl-1,3-dioxolane and trifluorochloroethylene in the perfluoro solvent is 30%~40%.

[0036] Preferably, the mixing described in step (2-1) is carried out at 40~65°C.

[0037] Preferably, the catalyst described in step (2-1) is perfluoropropionyl peroxide.

[0038] Preferably, the amount of catalyst added in step (2-1) is 0.01% to 0.02% of the mass of the perfluoro-2-methylene-4-methyl-1,3-dioxolane.

[0039] Preferably, step (2-1) further includes a step of removing the solvent after the polymerization reaction.

[0040] Preferably, the mass concentration of copolymer A in the composite membrane solution in step (2-2) is 0.05% to 0.2%.

[0041] Preferably, the amount of acetone added in step (2-2) is 2.5% of the mass of the perfluorinated solvent.

[0042] Preferably, the polytetrafluoroethylene film described in step (2-2) is prepared by hot pressing polyphenylene sulfide (PPS) nonwoven fabric and polytetrafluoroethylene (PTFE).

[0043] Preferably, the pore size of the base film described in step (2-2) is 10~15nm.

[0044] Compared with the prior art, the advantages of this invention are:

[0045] (1) This invention proposes a multi-step concentration and purification method that combines distillation, adsorption and membrane separation. The water evaporated through the distillation process can be collected and reused as electronic-grade ultrapure water. The adsorption and membrane separation system can effectively remove metal ions and particulate impurities from hydrofluoric acid waste liquid, and ultimately achieve the purpose of recycling electronic-grade hydrofluoric acid.

[0046] (2) In this invention, the concentration efficiency and product quality are ensured by precisely controlling the operating parameters of the distillation column, including the top temperature, bottom temperature, operating pressure, reflux ratio and nitrogen charging rate.

[0047] (3) The membrane material used in the first membrane separation system of the present invention has excellent chemical stability and corrosion resistance. For example, polysulfonamide membrane has a strong conjugation effect in its molecular structure, which makes it less susceptible to proton attack and thus exhibits excellent acid resistance, making it more suitable for treating waste liquid containing hydrofluoric acid. In addition, the removal of metal ions can be achieved by using the pore size sieving and surface chemical properties of the membrane: for example, polyamide membrane achieves the adsorption and removal of metal ions by forming coordination bonds with metal ions through polyamide groups, while polyethyleneimine membrane can achieve effective removal of metal ions through electrostatic and coordination effects.

[0048] (4) The adsorption tower of the present invention is filled with PHA chelating resin as an adsorbent. PHA resin has good acid resistance, and the -N(OH)-CO- double coordination group of hydroxamic acid has two atoms N and O with lone pairs of electrons. The positions of these two atoms are adjacent, which makes hydroxamic acid have a strong chelating effect on many metal ions. Chelation can form stable four-membered ring and five-membered ring compounds, thus effectively removing metal ions such as Ni from hydrofluoric acid waste liquid. 2+ Pb 2+ Zn 2+ wait.

[0049] (5) In the second membrane separation system of the present invention, trace metal ions in hydrofluoric acid are further removed by the acid-resistant PMMD-CTFE perfluorinated membrane material, thereby improving the purity of the product and enabling it to achieve the purpose of electronic-grade hydrofluoric acid recycling. The PMMD-CTFE membrane material not only has excellent mechanical properties and chemical stability, but also controls the dissolution rate of the membrane material to an extremely low level of less than 10 ppt, and the total organic carbon content is less than 0.1 ppt, thus avoiding the potential impact of membrane material dissolution on product purity. In addition, it can also remove possible trace particulate impurities during the adsorption process, ensuring the purity and reliability of the final product.

[0050] (6) In this invention, the distillation device, adsorption tower and membrane module all adopt corrosion-resistant inner layer structure. Through special material selection and process design, not only is the durability and corrosion resistance of the equipment improved, but also the efficiency and feasibility of the whole process method in treating hydrofluoric acid waste liquid are ensured, providing an innovative, environmentally friendly and economical solution for the purification and recycling of waste acid in the electronics industry. Beneficial effects

[0051] Type a paragraph here describing the beneficial effects. Attached Figure Description

[0052] Type the accompanying description paragraph here. The best embodiment of the present invention

[0053] Type the description paragraph of the best embodiment of the invention here. Embodiments of the present invention Example

[0054] (1) Preparation of PHA chelating resin:

[0055] (1-1) Add 2 g of sodium persulfate as a thermal initiator to an aqueous solution (500 mL) of a mixture of 100 g acrylamide and 20 g N,N-methylene-bisacrylamide, and heat in a water bath at 60 °C for 15-30 min to initiate the polymerization reaction to obtain the polymer;

[0056] (1-2) The polymer is crushed and washed, then placed in a 0.5M hydroxylamine hydrochloride solution for 30 minutes to form hydroxamic acid groups; then the pH is adjusted to 12 with a 1M sodium hydroxide solution, the mixture is left overnight and neutralized with 3M hydrochloric acid, and then washed to obtain the PHA chelating resin.

[0057] (1-3) Soak the PHA chelating resin in deionized water for 1-1.5 hours. After soaking, wash the resin with 4%-6%wt H2SO4, deionized water and 4%-6%wt NaOH alternately 3-5 times. Finally, wash with deionized water until neutral. After drying, fill the adsorption tower with a filling height of 1 / 3 to 1 / 2 of the height of the adsorption tower.

[0058] (2) Preparation of PMMD-CTFE membrane material:

[0059] Perfluoro-2-methylene-4-methyl-1,3-dioxolane and trifluorochloroethylene were added to a perfluoro solvent in a mass ratio of 1:6. The perfluoro solvent used was Fluorinert FC-72, and the combined mass concentration of perfluoro-2-methylene-4-methyl-1,3-dioxolane and trifluorochloroethylene was 35%.

[0060] The mixture was heated and stirred at 60°C to ensure thorough mixing and dissolution of the raw materials. Then, perfluoropropionyl peroxide (PFAP) was added as a catalyst at a mass of 0.015% of the mass of perfluoro-2-methylene-4-methyl-1,3-dioxolane. Polymerization was then carried out, and the solvent was removed by evaporation to obtain copolymer A.

[0061] The obtained copolymer A was dissolved in a perfluorinated solvent to achieve a copolymer A mass concentration of 0.18%. The perfluorinated solvent effectively dissolved copolymer A during the dissolution process, ensuring the uniformity and stability of the composite membrane solution. Subsequently, acetone at a mass ratio of 2.5% of the perfluorinated solvent was added to the solution, and the mixture was heated and stirred at 80°C for 20 hours to form the composite membrane solution.

[0062] The prepared composite membrane solution was coated onto the surface of a PTFE base membrane and dried at 80°C for 11 hours to obtain an acid-resistant composite membrane. The PTFE base membrane was prepared by hot pressing of polyphenylene sulfide (PPS) nonwoven fabric and polytetrafluoroethylene (PTFE), and the pore size of the base membrane was 14 nm.

[0063] (3) 10%wt hydrofluoric acid waste liquid is fed into a distillation column, and nitrogen gas is simultaneously introduced into the distillation column for distillation treatment. The absolute operating pressure of the distillation column is controlled at 0.1 MPa, the reflux ratio is 0.1, and the N2 charging rate is 0.1 Nm. 3 / h, the top temperature of the distillation column is 100℃ and the bottom temperature is 110℃; the inner wall of the distillation column has a polytetrafluoroethylene layer.

[0064] The treated water is collected from the light component outlet and can be reused as electronic-grade ultrapure water; the concentrated hydrofluoric acid is collected from the side outlet of the distillation column.

[0065] (4) The hydrofluoric acid solution after distillation is further sent to the first membrane separation system, where most of the metal ions in the hydrofluoric acid solution are removed by the first membrane separation system equipped with an acid-resistant membrane assembly.

[0066] (5) The treated hydrofluoric acid solution is further fed into the adsorption tower, where PHA chelating resin is used as an adsorbent to remove a small amount of metal ions from the solution.

[0067] (6) The treated hydrofluoric acid solution is finally sent to the second membrane separation system. Under the action of PMMD-CTFE membrane material, trace metal ions and particulate impurities in hydrofluoric acid are further removed. The final metal ion removal rate is ≥99.5%. 37%wt hydrofluoric acid product is collected on the permeate side to achieve the purpose of electronic grade hydrofluoric acid recycling. Example

[0068] (1)~(2) Same as Example 1.

[0069] (3) 10%wt hydrofluoric acid waste liquid is fed into a distillation column, and nitrogen gas is simultaneously introduced into the distillation column for distillation treatment. The absolute operating pressure of the distillation column is controlled at 0.02MPa, the reflux ratio is 0.5, and the N2 charging rate is 0.5 Nm. 3The distillation column has a top temperature of 60°C and a bottom temperature of 70°C per hour. The inner wall of the distillation column is lined with polytetrafluoroethylene (PTFE). The treated water is collected from the light component outlet and can be reused as electronic-grade ultrapure water; the concentrated hydrofluoric acid is collected from the distillation column side outlet.

[0070] (4) The hydrofluoric acid solution after distillation is further sent to the first membrane separation system, where most of the metal ions in the hydrofluoric acid solution are removed by the first membrane separation system equipped with an acid-resistant membrane assembly.

[0071] (5) The treated hydrofluoric acid solution is further fed into the adsorption tower, where PHA chelating resin is used as an adsorbent to remove a small amount of metal ions from the solution.

[0072] (6) The treated hydrofluoric acid solution is finally sent to the second membrane separation system. Under the action of PMMD-CTFE membrane material, trace metal ions and particulate impurities in hydrofluoric acid are further removed. The final metal ion removal rate is ≥99.8%. 37.5%wt hydrofluoric acid product is collected on the permeate side, achieving the purpose of recycling electronic grade hydrofluoric acid. Example

[0073] (1)~(2) Same as Example 1.

[0074] (3) 10%wt hydrofluoric acid waste liquid is fed into a distillation column, and nitrogen gas is simultaneously introduced into the distillation column for distillation treatment. The operating pressure of the distillation column is controlled at 0.05 MPa, the reflux ratio is 1, and the N2 charging rate is 1 Nm. 3 The distillation column has a top temperature of 90°C and a bottom temperature of 100°C per hour. The inner wall of the distillation column is lined with PFA. The treated water is collected from the light component outlet via the first condenser and can be reused as electronic-grade ultrapure water; the concentrated hydrofluoric acid is collected from the distillation column side outlet.

[0075] (4) The hydrofluoric acid solution after distillation is further sent to the first membrane separation system, where most of the metal ions in the hydrofluoric acid solution are removed by the first membrane separation system equipped with an acid-resistant membrane assembly.

[0076] (5) The treated hydrofluoric acid solution is further fed into the adsorption tower, where PHA chelating resin is used as an adsorbent to remove a small amount of metal ions from the solution.

[0077] (6) The treated hydrofluoric acid solution is finally sent to the second membrane separation system. Under the action of PMMD-CTFE membrane material, trace metal ions and particulate impurities in hydrofluoric acid are further removed. The final metal ion removal rate is ≥99.2%. 35%wt hydrofluoric acid product is collected on the permeate side to achieve the purpose of electronic grade hydrofluoric acid recycling.

[0078] Test case

[0079] The analytical results of the electronic-grade hydrofluoric acid products in Examples 1-3 are shown in Table 1.

[0080] Index E2 E3 Raw Material Example 1 Example 2 Example 3 Particles (≥0.5μm) pcs / mL ≤50 ≤25 228 6000 2015 30 Particles (≥1.0μm) pcs / mL ≤25 ≤10 358 40000 10 2015 Fluorosilicon (SiF4) 2- ) mg / kg ≤50 ≤50 1036520.5 25.0 32.5 Nitrate (NO3) - ) mg / kg≤3≤35.61.51.00.8 Sulfate (SO4) mg / kg≤5≤0.54.30.20.10.05 Phosphate (PO4) 3-) mg / kg≤1≤0.52.60.050.10.08 Aluminum (Al) μg / kg≤50≤1090.33.55.52.8 Arsenic (As) μg / kg≤50≤10160.52.53.21.0 Gold (Au) μg / kg≤20≤1010.80.50.60.5 Silver (Ag) μg / kg≤20≤1010.30.020.050.1 Boron (B) μg / kg≤20≤1062001.00.50.2 Barium (Ba) μg / kg≤50≤109.60.020.050.05 Beryllium (Be) μg / kg≤50≤103.60.050.060 0.06 Bismuth (Bi) μg / kg ≤50 ≤10 10.2 0.01 0.01 0.05 Calcium (Ca) μg / kg ≤50 ≤10 500 0.5 0.8 0.4 Cadmium (Cd) μg / kg ≤20 ≤10 20 0.8 0.5 0.5 Cobalt (Co) μg / kg ≤50 ≤10 7.6 0.5 0.4 0.2 Chromium (Cr) μg / kg ≤20 ≤10 5.8 0.5 0.8 0.5 Copper (Cu) μg / kg ≤50 ≤10 60 0.4 0.6 0.6 Iron (Fe) μg / kg ≤50 ≤10 89 0.8 0.4 0.4 Gallium (Ga) μg / kg ≤50 ≤10 36 0.4 0.3 0.2 Germanium (Ge) μ g / kg≤50≤105.60.60.40.8In (In) μg / kg≤50≤1020.50.10.10.2Potassium (K) μg / kg≤50≤103000.20.20.4Lithium (Li) μg / kg≤10≤5200.20.20.1Magnesium (Mg) μg / kg≤20≤10830.40.40.2Manganese (Mn) μg / kg≤20≤10100.71.22.5Molybdenum (Mo) μg / kg≤20≤108.51.01.51.4Sodium (Na) μg / kg≤50≤101077000.81.61.8Nickel (Ni) μg / kg≤20≤10 820.80.60.4 Lead (Pb) μg / kg≤20≤108971.51.40.8 Platinum (Pt) μg / kg≤50≤105.60.80.80.8 Antimony (Sb) μg / kg≤20≤108.51.00.40.6 Tin (Sn) μg / kg≤20≤109.50.40.60.7 Strontium (Sr) μg / kg≤50≤105.81.41.51.2 Titanium (Ti) μg / kg≤50≤10161.81.62.0 Vanadium (V) μg / kg≤50≤105.40.40.50.3 Zinc (Zn) μg / kg≤50≤101531.41.82.2

[0081] The table above is to illustrate the components contained in hydrofluoric acid. The content of these components is greatly related to their source, but this does not limit the applicability of the invention. The hydrofluoric acid product purified and recovered by this method meets the electronic grade recycling standard.

[0082] The embodiments described above are merely illustrative of specific implementations of the present invention, and while the descriptions are detailed, they should not be construed as limiting the scope of the present invention. It should be noted that those skilled in the art can make various modifications and improvements without departing from the concept of the present invention, and these modifications and improvements all fall within the scope of protection of the present invention. Therefore, the scope of protection of this patent should be determined by the appended claims. Industrial applicability

[0083] Type the industrial utility description paragraph here. Sequence List Free Content

[0084] Type the free content description paragraph for the sequence list here.

Claims

1. A method for purification and recovery of spent hydrofluoric acid in the electronic industry, characterized by, Includes the following steps: (1) the hydrofluoric acid waste liquid is sent into a rectifying tower, and nitrogen is filled into the rectifying tower at the same time for rectification treatment, the top temperature of the rectifying tower is 90-100 DEG C, the bottom temperature is 100-110 DEG C, the operating pressure is controlled to be 0.1-0.5 Mpa, the reflux ratio is 0.1-1, the filling rate of nitrogen is 0.1-1 Nm 3 / h, the inner wall of the rectifying tower has a corrosion-proof layer; (2) the rectification treatment is completed, and the treated hydrofluoric acid waste liquid is obtained; (2) The side stream distillate from the distillation column is fed into the first membrane separation system for membrane separation treatment. The membrane material of the first membrane separation system is an acid-resistant membrane. (3) The permeate obtained from the first membrane separation system is sent to the adsorption tower for adsorption treatment to remove some of the metal ions in the feed liquid; the inner wall of the adsorption tower is provided with an anti-corrosion material layer. (4) The feed liquid treated by the adsorption tower is sent to the second membrane separation system for membrane separation treatment. The membrane material of the second membrane separation system is an acid-resistant demetallization membrane to further remove trace metal ions and particulate impurities in the feed liquid. Recovered electronic-grade hydrofluoric acid is obtained on the permeate side of the second membrane separation system.

2. The purification recovery method according to claim 1, characterized by, The anti-corrosion layer mentioned in step (1) is a PTFE layer or a PFA layer.

3. The purification recovery method according to claim 1, characterized by, The acid-resistant membrane mentioned in step (2) is a composite membrane material of one or more of polyamide, polysulfonamide or polyethyleneimine.

4. The purification recovery method according to claim 1, characterized by, The first membrane separation system described in step (2) includes multiple sets of acid-resistant membrane modules connected in series or in parallel, and the liner of the acid-resistant membrane modules is PFA or PTFE resin.

5. The purification recovery method according to claim 1, characterized by, The anti-corrosion material layer mentioned in step (3) is PTFE or PFA.

6. The purification recovery method according to claim 1, characterized by The adsorption tower described in step (3) is filled with acid-resistant chelating resin as an adsorbent, and the filling height of the adsorbent accounts for 1 / 3 to 1 / 2 of the height of the adsorption tower.

7. The purification recovery method according to claim 1, characterized by, The acid-resistant chelating resin is a PHA chelating resin, and more preferably, the PHA chelating resin is prepared by the following method: (1-1) Sodium persulfate was added as a thermal initiator to an aqueous solution of acrylamide and N,N-methylene-bisacrylamide mixture, and the mixture was heated in a water bath at 60°C for 15-30 min to initiate the polymerization reaction and obtain the polymer. (1-2) The polymer is placed in a hydroxylamine hydrochloride solution for 30 min to form hydroxamic acid groups; The pH was then adjusted to 12 with sodium hydroxide solution, the mixture was left to stand overnight and neutralized with acid, and then washed to obtain the PHA chelating resin.

8. The purification recovery method according to claim 7, characterized by, The PHA chelating resin undergoes pretreatment before use, and the pretreatment includes: The PHA chelating resin was soaked in water for 1 to 1.5 hours, and then washed 3 to 5 times with 4% to 6% wt H2SO4, water, and 4% to 6% wt NaOH, and finally washed with water until neutral.

9. The purification recovery method according to claim 1, characterized by, The second membrane separation system described in step (4) includes multiple sets of acid-resistant demetallization membrane modules connected in series or in parallel, wherein the membrane material of the acid-resistant demetallization membrane module is perfluorinated PMMD-CTFE membrane material.

10. The purification recovery method according to claim 9, characterized by, The perfluorinated PMMD-CTFE membrane material is prepared by the following steps: (1) Preparation of copolymer A: Perfluoro-2-methylene-4-methyl-1,3-dioxolane and trifluorochloroethylene were mixed in a perfluoro solvent and polymerized in the presence of a catalyst to obtain copolymer A. (2) Preparation of acid-resistant composite membrane: The copolymer A and acetone are mixed in a perfluorinated solvent at 60-80°C to obtain a composite film liquid. The composite film liquid is then coated on the surface of a polytetrafluoroethylene film and dried to obtain the acid-resistant composite film.