An acid recovery process based on nanofiltration - reverse osmosis

Abstract

This invention discloses an acid recovery process based on nanofiltration-reverse osmosis, belonging to the field of wastewater treatment technology. The acid recovery process includes the following steps: Step 1, chemical polishing wastewater is treated with an extraction resin to adsorb aluminum ions; the effluent is concentrated by evaporation and used as recycled chemical polishing tank acid solution; Step 2, the adsorbed extraction resin is desorbed using distilled water; the resulting desorbed solution is subjected to diffusion dialysis to separate aluminum ions, and the recovered acid solution is separated by nanofiltration; Step 3, the nanofiltration dilute solution is concentrated by reverse osmosis to obtain concentrated acid solution, which is used as recycled sulfuric acid desorbate; Step 4, the diffusion dialysis residue, nanofiltration concentrate, and reverse osmosis dilute solution are neutralized with alkali to prepare an aluminum-containing flocculant. By combining adsorption, diffusion dialysis, nanofiltration, and reverse osmosis processes, and using an amino-containing imidazolium salt-modified polyamide nanofiltration membrane and a reverse osmosis membrane containing phosphonic acid-sulfonic acid bifunctional groups, efficient separation and recovery of acid and aluminum ions in chemical polishing wastewater are achieved, reducing costs while increasing economic benefits.

Description

Technical Field

[0001] This invention belongs to the field of wastewater treatment technology, specifically relating to an acid recovery process based on nanofiltration-reverse osmosis. Background Technology

[0002] Anodizing is the most important surface treatment technology for aluminum alloys, with wide applications in daily chemicals, automotive trim parts, construction, aerospace, and electrical and electronic industries. During the anodizing process, high-concentration waste acid is continuously generated. Traditional chemical treatment methods for this waste acid are costly. Therefore, it is necessary to adopt alternative methods to recover the waste acid from the anodizing and polishing solutions.

[0003] Currently, the resin adsorption process for aluminum removal and acid recovery can turn waste into treasure and make waste acid a resource. It has the advantages of simple process, low energy consumption and low equipment price, and has great potential for promotion and application. However, the resin after adsorption needs to be desorbed and regenerated, which will generate a large amount of acid-containing desorption liquid. Therefore, solving the problem of acid recovery in desorption liquid can further improve the economic benefits of chemical waste liquid recovery and reduce acid pollution. Summary of the Invention

[0004] The purpose of this invention is to provide an acid recovery process based on nanofiltration-reverse osmosis to achieve efficient recovery of acid from chemical polishing wastewater generated during the anodizing process.

[0005] The objective of this invention can be achieved through the following technical solutions:

[0006] This invention provides an acid recovery process based on nanofiltration-reverse osmosis, comprising the following steps:

[0007] Step 1: The chemical polishing waste liquid is treated with an extraction resin to adsorb aluminum ions, and the effluent is concentrated by evaporation and reused as acid solution from the chemical polishing tank.

[0008] Step 2: The adsorbed resin is desorbed using distilled water. The resulting desorbed solution is then subjected to diffusion dialysis to separate aluminum ions, and the recovered acid solution is then separated using nanofiltration.

[0009] Step 3: The nanofiltration dilute solution is concentrated by reverse osmosis to obtain concentrated acid solution, which is used as the recycled sulfuric acid desorption solution;

[0010] Step 4: Neutralize the diffusion dialysis residue, nanofiltration concentrate, and reverse osmosis dilute solution with alkali to prepare an aluminum-containing flocculant.

[0011] Chemical polishing wastewater contains large amounts of sulfuric acid, phosphoric acid, and aluminum ions. Extraction resin can adsorb aluminum ions through cation exchange, significantly reducing the aluminum ion content in the effluent. The acid concentration can then be increased through evaporation and concentration for reuse as acid in the chemical polishing tank. After adsorption, the cation exchange resin needs desorption and regeneration. The desorption solution is an acidic solution containing a high concentration of aluminum ions. During diffusion dialysis, most of the aluminum ions are blocked, leaving a high-concentration aluminum ion solution as the residual liquid. The recovered acid solution has a high acid concentration, which can be further removed by nanofiltration. The acid in the nanofiltration dilute solution is then concentrated by reverse osmosis to achieve high-concentration acid recovery.

[0012] Furthermore, in step one, the ratio of the extraction resin to the chemical polishing waste liquid is 0.03-0.05 g / mL, and the adsorption time for aluminum ions is 5-10 h.

[0013] Furthermore, the nanofiltration membrane used is an imidazolium salt-modified polyamide nanofiltration membrane containing amino groups.

[0014] Furthermore, the reverse osmosis membrane used in the reverse osmosis is a reverse osmosis membrane containing phosphoric acid-sulfonic acid bifunctional groups.

[0015] Furthermore, the total acid concentration in the chemical polishing waste liquid is 3-30 wt%, and the aluminum ion concentration is 1200-11000 mg / L.

[0016] Furthermore, the phosphorus-to-sulfur ratio in the chemical waste liquid is 4-10.

[0017] Furthermore, the preparation steps of the extraction resin are as follows:

[0018] Immerse AB-8 or X-5 resin in anhydrous ethanol at a concentration of 0.1-0.5 g / mL, stir magnetically for 1-4 h, filter under reduced pressure, wash the filter cake twice with 5-15 wt% sodium carbonate solution, wash with ultrapure water until neutral, dry at 50-70℃, place in a beaker, add extractant and anhydrous ethanol in sequence, stir magnetically for 12-24 h, vacuum evaporate in a rotary evaporator at 40-60℃ until the resin is fluffy, and dry at 50-60℃ to obtain the extraction resin.

[0019] The adsorption resin is a modified extractant resin that exhibits high selectivity for aluminum ions, enabling efficient adsorption of aluminum ions in acidic solutions and improving the recovery rate of aluminum ions.

[0020] Furthermore, the extractant is one of TBP, P204, and Cyanex 272, and the mass ratio of extractant to resin is 3-4:5.

[0021] Furthermore, the preparation steps of the nanofiltration membrane are as follows:

[0022] A 0.1-0.3 wt% piperazine aqueous solution was poured onto a polysulfone-based membrane with a molecular weight cutoff of 200-500 Da. After standing for 2-5 minutes, the solution was removed, and the membrane was dried at room temperature. Then, the membrane was immersed in a 0.1-0.5 wt% trimesoyl chloride solution for interfacial polymerization for 1-2 minutes. After removing the solution and drying at room temperature, the membrane was immersed in a 2-5 wt% 1-aminopropyl-3-methylimidazolium bromide aqueous solution. After standing for 10-30 minutes, the solution was removed, and the membrane was dried at room temperature. After washing with deionized water, the membrane was dried to obtain a nanofiltration membrane.

[0023] Piperazine and pyromellitic trimethylol chloride were interfacially polymerized on a polysulfone-based membrane to prepare a polymer-interwoven polyamide nanofiltration membrane. After interfacial polymerization, the unreacted acyl chloride groups on the membrane surface combined with the amino groups in 1-aminopropyl-3-methylimidazolium bromide through an amidation reaction, fixing positively charged imidazolium groups on the membrane surface, increasing the positive charge concentration on the nanofiltration membrane surface, enhancing the repulsion of metal ions, and the imidazolium groups that did not participate in interfacial polymerization led to the expansion of the polyamide network pores and provided more channels.

[0024] Furthermore, the solvent used in the pyromellitic pyromellitic chloride solution is one of n-hexane and dimethyl sulfoxide.

[0025] Furthermore, the preparation steps of the reverse osmosis membrane are as follows:

[0026] A 1-3 wt% aqueous solution of m-phenylenediamine is poured onto a polysulfone-based membrane with a molecular weight cutoff of 50-100 Da. After standing for 2-5 minutes, the solution is removed, and the membrane is dried at room temperature. Then, it is immersed in a 0.1-0.5 wt% solution of m-phenylenediamine sulfonyl chloride for interfacial polymerization for 1-2 minutes. After removing the solution and drying at room temperature, the membrane is immersed in a 2-4 wt% aqueous solution of ethylenediamine. After standing for 5-10 minutes, the membrane is removed, washed three times with deionized water, and then immersed in a 5-15 wt% aqueous solution of formaldehyde and phosphorous acid (the mass ratio of formaldehyde to phosphorous acid is 1:1-3). The membrane is soaked at 60-80℃ for 3-5 hours, washed with deionized water, and dried to obtain a reverse osmosis membrane containing phosphonic acid-sulfonic acid bifunctional groups.

[0027] By introducing sulfonic acid groups and phosphate groups onto the reverse osmosis membrane, the rejection rate of acid can be improved by increasing the negative charge density on the membrane surface, thereby enhancing the hydrophilicity and selectivity of the membrane and effectively improving water treatment efficiency.

[0028] The beneficial effects of this invention are:

[0029] (1) By combining adsorption, diffusion dialysis, nanofiltration and reverse osmosis processes, the acid and aluminum ions in the chemical waste liquid are separated efficiently. The acid liquid of different concentrations and the solution containing aluminum ions generated during the recycling process are actively reused to achieve efficient recovery of acid and aluminum ions, reduce costs and increase economic benefits.

[0030] (2) The preparation of amino-containing imidazolium salt-modified polyamide nanofiltration membrane and phosphonic acid-sulfonic acid bifunctional membrane can improve the retention of aluminum ions and the concentration of acid, increase the recovery rate, and eliminate the need for secondary recovery, making the process simple. Detailed Implementation

[0031] The technical solutions of the present invention will be clearly and completely described below with reference to the embodiments of the present invention. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative effort are within the scope of protection of the present invention.

[0032] Example 1

[0033] Preparation of extraction resin:

[0034] 100g of AB-8 resin was soaked in 200mL of anhydrous ethanol and magnetically stirred for 2h. After vacuum filtration, the filter cake was washed twice with 5wt% sodium carbonate solution and rinsed with ultrapure water until neutral. It was dried at 50℃ and placed in a beaker. 80g of TBP and 250mL of anhydrous ethanol were added sequentially and magnetically stirred for 24h. The resin was vacuum evaporated at 40℃ until it became fluffy. It was then dried at 50℃ to obtain the extraction resin.

[0035] Preparation of nanofiltration membranes:

[0036] A 0.1 wt% piperazine aqueous solution was poured onto a polysulfone-based membrane with a molecular weight cutoff of 200-500 Da. After standing for 5 min, the solution was removed, and the membrane was air-dried at room temperature. Then, the membrane was immersed in a 0.5 wt% pyromellitic chlorohexane solution for interfacial polymerization for 2 min. After removing the solution, the membrane was air-dried at room temperature and then immersed in a 2 wt% 1-aminopropyl-3-methylimidazolium bromide aqueous solution. After standing for 30 min, the membrane was removed, and the membrane was air-dried at room temperature. After washing with deionized water, the membrane was dried to obtain a nanofiltration membrane.

[0037] Preparation of reverse osmosis membranes:

[0038] A 2 wt% aqueous solution of m-phenylenediamine was poured onto a polysulfone-based membrane with a molecular weight cutoff of 50-100 Da. After standing for 2 minutes, the solution was removed, and the membrane was dried at room temperature. Then, it was immersed in a 0.1 wt% solution of m-phenylenediamine sulfonyl chloride for interfacial polymerization for 2 minutes. After removing the solution and drying at room temperature, the membrane was immersed in a 3 wt% aqueous solution of ethylenediamine and stood for 5 minutes. After removing the solution, the membrane was washed three times with deionized water and then immersed in a 10 wt% aqueous solution of formaldehyde and phosphorous acid (mass ratio of formaldehyde to phosphorous acid 1:1) at 70°C for 3 hours. After washing with deionized water and drying, a reverse osmosis membrane containing phosphonic acid-sulfonic acid bifunctional groups was obtained.

[0039] The total acid concentration of the chemical polishing waste liquid provided in this embodiment is 4.13 wt%, the aluminum ion concentration is 1211.9 mg / L, and the phosphorus-to-sulfur ratio is 4. The acid is recovered using the following process steps:

[0040] Step 1: The extraction resin prepared in the example is packed into a resin column. The chemical polishing waste liquid flows countercurrently from bottom to top through the resin-filled bed. The ratio of extraction resin to chemical polishing waste liquid is 0.03 g / mL, the flow rate is about 2.33 mL / min, and a total of 1 L of chemical polishing waste liquid is injected. After the extraction resin adsorbs aluminum ions, the effluent is evaporated and concentrated to be used as recycled chemical polishing tank acid solution.

[0041] Step 2: Wash the adsorbed extraction resin with distilled water from top to bottom in a co-current manner until the concentration of acid and aluminum ions in the desorption solution drops to the minimum, then stop the desorption. Collect the desorption solution and send it to a diffusion dialysis device. After diffusion dialysis, aluminum ions are separated. The bilateral flow ratio is set to 1:1, the desorption solution flux is set to 0.34 L / h, and the flow ratio of the recovered acid solution and the residual solution at the outlet is about 1.3:1. Collect the recovered acid solution and send it to a nanofiltration device for separation. The nanofiltration device uses the nanofiltration membrane prepared in this embodiment. The aluminum rejection rate of the nanofiltration device is 98.9%, and the total acid permeation rate is 82.5%.

[0042] Step 3: The nanofiltration dilute solution is concentrated by reverse osmosis to obtain concentrated acid solution. The reverse osmosis uses the reverse osmosis membrane prepared in Example 1. The total acid permeation rate of reverse osmosis is 6.2%, and the aluminum rejection rate is 92.3%. The concentrated acid solution is used as the sulfuric acid desorption solution for reuse.

[0043] Step 4: After neutralizing the diffusion dialysis residue, nanofiltration concentrate, and reverse osmosis dilute solution with alkali, an aluminum-containing flocculant is prepared.

[0044] By detecting the total acid concentration in the effluent after adsorption by the extraction resin, the total acid concentration in the concentrated acid solution, the aluminum ion concentration in the diffusion dialysis residue, the aluminum ion concentration in the nanofiltration concentrate, and the aluminum ion concentration in the reverse osmosis dilute solution, the total acid recovery rate in the acid recovery process of Example 1 was found to be 93.3%, and the aluminum ion recovery rate was 87.6%.

[0045] Example 2

[0046] The difference from Example 1 is that TBP in the preparation of the extraction resin is replaced with P204, while the other steps and conditions are the same as in Example 1.

[0047] Correspondingly, due to the change in the adsorption performance of the extraction resin, the concentration of the desorbed solution after desorption changes, affecting the parameters of subsequent processes. Specifically, the aluminum rejection rate of nanofiltration is 98.3%, the total acid permeation rate is 84.4%, and the total acid permeation rate of reverse osmosis is 5.9%, with an aluminum rejection rate of 92.0%.

[0048] In this embodiment, the total acid recovery rate in the acid recovery process is 92.7%, and the aluminum ion recovery rate is 85.0%.

[0049] Example 3

[0050] The difference from Example 1 is that TBP in the preparation of the extraction resin is replaced with Cyanex 272, while the other steps and conditions are the same as in Example 1.

[0051] Correspondingly, due to the change in the adsorption performance of the extraction resin, the concentration of the desorbed solution after desorption changes, affecting the parameters of subsequent processes. Specifically, the aluminum rejection rate of nanofiltration is 99.2%, and the total acid permeation rate is 80.6%, while the total acid permeation rate of reverse osmosis is 6.5%, and the aluminum rejection rate is 92.5%.

[0052] In this embodiment, the total acid recovery rate in the acid recovery process is 93.9%, and the aluminum ion recovery rate is 88.7%.

[0053] Example 4

[0054] The difference from Example 3 is that the concentration of 1-aminopropyl-3-methylimidazolium bromide aqueous solution was increased to 4 wt% in the preparation of nanofiltration membrane, while the other steps and conditions were the same as in Example 3.

[0055] Correspondingly, due to the change in the separation performance of the nanofiltration membrane, the concentration of the nanofiltration dilute solution changes, affecting the parameters of subsequent processes. Specifically, the aluminum rejection rate of nanofiltration is 99.6%, and the total acid permeation rate is 83.4%, while the total acid permeation rate of reverse osmosis is 6.6%, and the aluminum rejection rate is 92.2%.

[0056] In this embodiment, the total acid recovery rate in the acid recovery process is 94.5%, and the aluminum ion recovery rate is 92.4%.

[0057] Example 5

[0058] The difference from Example 3 is that the concentration of 1-aminopropyl-3-methylimidazolium bromide aqueous solution was increased to 5 wt% in the preparation of nanofiltration membrane, while the other steps and conditions were the same as in Example 3.

[0059] Correspondingly, due to the change in the separation performance of the nanofiltration membrane, the concentration of the nanofiltration dilute solution changes, affecting the parameters of subsequent processes. Specifically, the aluminum rejection rate of nanofiltration is 99.5%, and the total acid permeation rate is 83.2%, while the total acid permeation rate of reverse osmosis is 6.3%, and the aluminum rejection rate is 92.3%.

[0060] In this embodiment, the total acid recovery rate in the acid recovery process is 94.0%, and the aluminum ion recovery rate is 91.1%.

[0061] Example 6

[0062] The difference from Example 4 is that the concentration of ethylenediamine aqueous solution in the preparation of the reverse osmosis membrane is reduced to 2 wt%, and the concentration of formaldehyde and phosphorous acid aqueous solution is reduced to 5 wt%, while the other steps and conditions are the same as in Example 4.

[0063] Correspondingly, due to the change in the separation performance of the reverse osmosis membrane, the total acid permeation rate of reverse osmosis was 5.0%, and the aluminum rejection rate was 92.5%.

[0064] In this embodiment, the total acid recovery rate in the acid recovery process is 96.7%, and the aluminum ion recovery rate is 92.0%.

[0065] Example 7

[0066] The difference from Example 4 is that the concentration of ethylenediamine aqueous solution in the preparation of the reverse osmosis membrane is increased to 4 wt%, and the concentration of formaldehyde and phosphorous acid aqueous solution is increased to 15 wt%, while the other steps and conditions are the same as in Example 4.

[0067] Correspondingly, due to the change in the separation performance of the reverse osmosis membrane, the total acid permeation rate of reverse osmosis was 4.7%, and the aluminum rejection rate was 92.6%.

[0068] In this embodiment, the total acid recovery rate in the acid recovery process is 97.0%, and the aluminum ion recovery rate is 91.9%.

[0069] Comparative Example 1

[0070] Compared to Example 1, the nanofiltration membrane in this comparative example was prepared without the addition of an aqueous solution of 1-aminopropyl-3-methylimidazolium bromide, while the other steps and conditions were the same as in Example 1.

[0071] Preparation of nanofiltration membranes:

[0072] A 0.1 wt% piperazine aqueous solution was poured onto a polysulfone-based membrane with a molecular weight cutoff of 200-500 Da. After standing for 5 minutes, the solution was removed, and the membrane was dried at room temperature. Then, it was immersed in a 0.5 wt% pyromellitic chlorohexane solution for interfacial polymerization for 2 minutes. After removing the solution, the membrane was dried at room temperature, washed with deionized water, and dried to obtain a nanofiltration membrane.

[0073] Correspondingly, due to the change in the separation performance of the nanofiltration membrane, the concentration of the nanofiltration dilute solution changes, affecting the parameters of subsequent processes. Specifically, the aluminum rejection rate of nanofiltration is 90.7%, the total acid permeation rate is 63.3%, and the total acid permeation rate of reverse osmosis is 6.1%, with an aluminum rejection rate of 92.2%.

[0074] In this comparative acid recovery process, the total acid recovery rate is 85.0%, and the aluminum ion recovery rate is 74.7%.

[0075] Comparative Example 2

[0076] Compared to Example 1, the reverse osmosis membrane in this comparative example was prepared without the addition of aqueous solutions of ethylenediamine, formaldehyde, and phosphorous acid. Other steps and conditions were the same as in Example 1.

[0077] Preparation of reverse osmosis membranes:

[0078] A 2 wt% aqueous solution of m-phenylenediamine was poured onto a polysulfone-based membrane with a molecular weight cutoff of 50-100 Da. After standing for 2 minutes, the solution was removed, and the membrane was dried at room temperature. Then, it was immersed in a 0.1 wt% solution of m-phenylenediamine sulfonyl chloride for interfacial polymerization for 2 minutes. After removing the solution, the membrane was washed with deionized water and dried to obtain a reverse osmosis membrane.

[0079] Correspondingly, due to the change in the separation performance of the reverse osmosis membrane, the total acid permeation rate of reverse osmosis was 10.6%, and the aluminum rejection rate was 92.1%.

[0080] In this comparative acid recovery process, the total acid recovery rate is 88.5%, and the aluminum ion recovery rate is 87.9%.

[0081] The data from the examples show that Example 7 achieved the highest acid recovery rate. Among Examples 1-3, Cyanex 272 was the optimal extractant for aluminum ions, resulting in the highest aluminum ion recovery rate. Examples 4 and 5, based on Example 3, increased the concentration of 1-aminopropyl-3-methylimidazolium bromide aqueous solution to increase the density of imidazolium groups loaded on the nanofiltration membrane, thereby improving the repulsion of metal ions. Example 4 achieved an aluminum ion recovery rate as high as 92.4%. Example 7 increased the negative charge density on the reverse osmosis membrane surface, significantly improving the total acid recovery rate compared to Example 4. In the comparative examples, the nanofiltration and reverse osmosis membranes were not modified, and their recovery efficiency was far lower than that of Example 1.

[0082] It should be noted that, in this document, relational terms such as "first" and "second" are used only to distinguish one entity or operation from another, and do not necessarily require or imply any such actual relationship or order between these entities or operations. Furthermore, the terms "comprising," "including," or any other variations thereof are intended to cover non-exclusive inclusion, such that a process, method, article, or apparatus that comprises a list of elements includes not only those elements but also other elements not expressly listed, or elements inherent to such process, method, article, or apparatus.

[0083] Although embodiments of the invention have been shown and described, it will be understood by those skilled in the art that various changes, modifications, substitutions and alterations can be made to these embodiments without departing from the principles and spirit of the invention, the scope of which is defined by the appended claims and their equivalents.

Claims

1. A nanofiltration-reverse osmosis based acid recovery process, characterized in that, Includes the following steps: Step 1: The chemical polishing waste liquid is treated with an extraction resin to adsorb aluminum ions, and the effluent is concentrated by evaporation and reused as acid solution from the chemical polishing tank. Step 2: The adsorbed resin is desorbed using distilled water. The resulting desorbed solution is then subjected to diffusion dialysis to separate aluminum ions, and the recovered acid solution is then separated using nanofiltration. Step 3: The nanofiltration dilute solution is concentrated by reverse osmosis to obtain concentrated acid solution, which is used as the recycled sulfuric acid desorption solution; Step 4: Neutralize the diffusion dialysis residue, nanofiltration concentrate, and reverse osmosis dilute solution with alkali to prepare an aluminum-containing flocculant; The preparation steps of the extraction resin are as follows: Immerse AB-8 or X-5 resin in anhydrous ethanol at a concentration of 0.1-0.5 g / mL, stir magnetically for 1-4 h, filter under reduced pressure, rinse the filter cake twice with 5-15 wt% sodium carbonate solution, rinse with ultrapure water until neutral, dry at 50-70℃, place in a beaker, add extractant and anhydrous ethanol in sequence, stir magnetically for 12-24 h, vacuum evaporate in a rotary evaporator at 40-60℃ until the resin is fluffy, and dry at 50-60℃ to obtain the extraction resin; The nanofiltration membrane used is an imidazolium salt-modified polyamide nanofiltration membrane containing amino groups. The preparation steps of the nanofiltration membrane are as follows: A 0.1-0.3 wt% piperazine aqueous solution was poured onto a polysulfone-based membrane with a molecular weight cutoff of 200-500 Da. After standing for 2-5 minutes, the solution was removed, and the membrane was air-dried at room temperature. Then, the membrane was immersed in a 0.1-0.5 wt% trimesoyl chloride solution for interfacial polymerization for 1-2 minutes. After removing the solution, the membrane was air-dried at room temperature and then immersed in a 2-5 wt% 1-aminopropyl-3-methylimidazolium bromide aqueous solution. After standing for 10-30 minutes, the membrane was removed, and the membrane was air-dried at room temperature. After washing with deionized water, the membrane was dried to obtain a nanofiltration membrane. The reverse osmosis membrane used is a reverse osmosis membrane containing phosphoric acid-sulfonic acid bifunctional groups; The preparation steps of the reverse osmosis membrane are as follows: A 1-3 wt% aqueous solution of m-phenylenediamine was poured onto a polysulfone-based membrane with a molecular weight cutoff of 50-100 Da. After standing for 2-5 minutes, the solution was removed, and the membrane was dried at room temperature. Then, it was immersed in a 0.1-0.5 wt% solution of m-phenylenedisulfonyl chloride for interfacial polymerization for 1-2 minutes. After removing the solution and drying at room temperature, the membrane was immersed in a 2-4 wt% aqueous solution of ethylenediamine. After standing for 5-10 minutes, the membrane was removed, washed three times with deionized water, and then immersed in a 5-15 wt% aqueous solution of formaldehyde and phosphorous acid (the mass ratio of formaldehyde to phosphorous acid was 1:1-3). The membrane was soaked at 60-80℃ for 3-5 hours, washed with deionized water, and dried to obtain a reverse osmosis membrane containing phosphonic acid-sulfonic acid bifunctional groups.

2. A nanofiltration-reverse osmosis based acid recovery process according to claim 1, characterized in that, In step one, the ratio of the extraction resin to the chemical polishing waste liquid is 0.03-0.05 g / mL, and the adsorption time of aluminum ions is 5-10 h.

3. A nanofiltration-reverse osmosis based acid recovery process according to claim 1, characterized in that, The solvent used in the pyromellitic pyromellitic chloride solution is one of n-hexane and dimethyl sulfoxide.

4. The nanofiltration-reverse osmosis based acid recovery process according to claim 1, characterized in that, The total acid concentration in the chemical polishing waste liquid is 3-30 wt%, and the aluminum ion concentration is 1200-11000 mg / L; The phosphorus-to-sulfur ratio in the chemical waste liquid is 4-10.

5. The nanofiltration-reverse osmosis based acid recovery process according to claim 1, wherein, The extractant is one of TBP, P204 and Cyanex272, and the mass ratio of extractant to resin is 3-4:5.