Polysulfonamide acid-resistant membrane with excellent separation performance as well as preparation method and application of polysulfonamide acid-resistant membrane

Abstract

The invention discloses a polysulfonamide acid-resistant membrane with excellent separation performance as well as a preparation method and application thereof. The preparation method comprises the following steps: soaking a porous support membrane in an amine water solution, soaking and taking out; soaking in a sulfonyl chloride solution containing a regulating agent, and carrying out interfacial polymerization reaction; the sulfonyl chloride solution containing the regulating agent consists of the regulating agent, sulfonyl chloride, a cosolvent and the balance of an organic solvent, the regulating agent is HNTf2, LiNTf2 or Ca (NTf2) 2; cleaning with an organic solvent; and placing in a constant-temperature environment of 60-100 DEG C to obtain the product. The membrane is high in crosslinking degree and smooth in surface, the retention rate of 2000ppm MgSO4 can reach 88.23% or above, the retention rate of MgSO4 is maintained to be 87.22% or above after the membrane is soaked in an H2SO4 aqueous solution with the pH value of 1 at 60 DEG C for 24 hours, and the membrane is stable in water flux and can be adapted to treatment of metallurgical / chemical acid wastewater with the pH value of 1-3.

Description

Technical Field

[0001] This invention relates to the intersection of water treatment material preparation and membrane separation technology, specifically to a polysulfonamide acid-resistant membrane with excellent separation performance, its preparation method, and its application. Background Technology

[0002] In the fields of industrial water treatment and resource recovery, membrane separation technology, with its advantages of low energy consumption, modularity, and no secondary pollution, is gradually replacing traditional processes such as distillation and ion exchange, becoming the mainstream technology. Water treatment membranes can be classified according to pore size and separation mechanism into microfiltration membranes (MF, 0.1-10μm), ultrafiltration membranes (UF, 0.001-0.1μm), nanofiltration membranes (NF, 0.0001-0.001μm), and reverse osmosis membranes (RO, <0.0001μm). Nanofiltration membranes, due to their combination of charge repulsion and pore size sieving, are widely used in water softening (removing calcium carbonate). 2+ Mg 2+ It is used for the removal of low-molecular-weight organic matter (dyes, antibiotics) and the separation of high-valence metal ions. In the treatment of acidic wastewater, the acid resistance and stability of the membrane are subject to strict requirements.

[0003] Current traditional nanofiltration membranes are prone to hydrolysis under acidic conditions due to their structural characteristics, which severely limits their application in the treatment of strongly acidic water bodies with pH < 3.

[0004] To address the issue of insufficient acid resistance, researchers have developed novel acid-resistant monomers to improve the stability of the separation layer at the molecular structure level. Examples include 1,3,6-naphthalenetrisulfonyl chloride NTSC and 1,3,5-benzenetrisulfonyl chloride BTSC. However, sulfonyl chloride monomers suffer from a key defect: low activity. This problem directly leads to two major technical bottlenecks: firstly, insufficient cross-linking of the separation layer, resulting in a loose membrane pore structure and uneven pore size distribution, which hinders the activity of divalent ions (such as Mg²⁺). 2+ SO4 2- The rejection rate of polysulfonamide membranes is typically below 70%, making it difficult to meet the requirements for advanced industrial wastewater treatment. Secondly, the monomer diffusion rate exceeds the reaction rate during the reaction, easily forming a rough, nodular surface morphology, increasing the adsorption area of ​​pollutants, and exacerbating membrane fouling. Therefore, how to improve the crosslinking degree and separation performance of polysulfonamide membranes by controlling the interfacial polymerization kinetics while ensuring their acid resistance has become a core challenge for the industrial application of this type of material. Summary of the Invention

[0005] The purpose of this invention is to overcome the shortcomings of the prior art and provide a polysulfonamide acid-resistant membrane with excellent separation performance.

[0006] The second objective of this invention is to provide a method for preparing a polysulfonamide acid-resistant membrane with excellent separation performance.

[0007] The third objective of this invention is to provide an application of a polysulfonamide acid-resistant membrane with excellent separation performance in the treatment of acidic wastewater.

[0008] The technical solution of this invention is summarized as follows: A method for preparing a polysulfonamide acid-resistant membrane with excellent separation performance includes the following steps: (1) Immerse the porous support membrane in an aqueous amine solution with a concentration of 1wt%-4wt% for 1-7 min, then remove it; then immerse it in a sulfonyl chloride solution containing a regulator for 3-7 min to allow interfacial polymerization to occur. The sulfonyl chloride solution containing the regulator consists of 0.01wt%-0.3wt% regulator, 0.01wt%-2wt% sulfonyl chloride, 0.01wt%-2wt% co-solvent, and the balance being an organic solvent; the regulator is HNTf2, LiNTf2, or Ca(NTf2)2; (2) The product obtained in step (1) is washed with an organic solvent and placed in a constant temperature environment of 60-100℃ for 1 min-7 min to obtain a polysulfonamide acid-resistant membrane with excellent separation performance.

[0009] Preferably, the porous support membrane is a polysulfone membrane or a polyethersulfone membrane.

[0010] Preferably, the amine is tri(2-aminoethyl)amine, triethylenetetramine, or tetraethylenepentamine.

[0011] Preferably, the sulfonyl chloride is 1,3,6-naphthalenetrisulfonyl chloride or 1,3,5-benzenetrisulfonyl chloride.

[0012] Preferably, the co-solvent is at least one selected from acetone, toluene, xylene, tetrahydrofuran, N,N-dimethylformamide, and dimethyl sulfoxide.

[0013] Preferably, the organic solvent in step (1) is n-hexane, cyclohexane, cyclopentane, n-heptane, or Isopar.

[0014] Preferably, the organic solvent in step (2) is n-hexane, cyclohexane, cyclopentane, n-heptane, or Isopar.

[0015] The above preparation method produces a polysulfonamide acid-resistant membrane with excellent separation performance.

[0016] The above-mentioned polysulfonamide acid-resistant membrane with excellent separation performance is used in the treatment of acidic wastewater.

[0017] Advantages of this invention: The polysulfonamide acid-resistant membrane of this invention exhibits excellent separation performance, effectively solving the problems of low crosslinking degree, rough surface, and poor acid resistance of existing polysulfonamide membranes. The polysulfonamide acid-resistant membrane prepared by the method of this invention has a high degree of crosslinking and a smooth surface. It can achieve a rejection rate of over 85% for 2000 ppm MgSO4.

[0018] The membranes prepared in each embodiment were soaked in an aqueous H₂SO₄ solution with pH=1 at 60°C for 24 hours. The MgSO₄ rejection rate remained above 87.22%, and the water flux remained stable (≥12.85 L·m⁻¹ at 1 MPa and 25°C). -2 ·h -1 This invention can be adapted to the treatment of acidic wastewater from metallurgical / chemical industries with a pH of 1-3. The membrane of this invention has low preparation cost and is easy to scale up industrially. Attached Figure Description

[0019] Figure 1 The nitrogen element is shown in the X-ray photoelectron spectroscopy (XPS) spectrum of a polysulfonamide acid-resistant membrane with excellent separation performance prepared in Example 1.

[0020] Figure 2 A scanning electron microscope image of a polysulfonamide acid-resistant membrane with excellent separation performance prepared in Example 1. Detailed Implementation

[0021] The present invention will be further described below through specific embodiments.

[0022] The following embodiments are for illustrative purposes only and do not constitute a limitation on the scope of protection. Experiments without specified conditions should be conducted according to conventional conditions in the field or the conditions recommended by reagent and instrument manufacturers; the reagents used are commercially available conventional products, and the instruments are commonly used commercial models in the industry.

[0023] The polysulfone membrane was purchased from Uniso Membrane Technology (Xiamen) Co., Ltd. The polyethersulfone membrane was purchased from Uniso Membrane Technology (Xiamen) Co., Ltd. Example 1 A method for preparing a polysulfonamide acid-resistant membrane with excellent separation performance includes the following steps: (1) Immerse the polysulfone membrane in a 2wt% aqueous solution of amine (tetraethylenepentamine) for 5 min, then remove it; then immerse it in a sulfonyl chloride solution containing a regulator for 5 min to undergo interfacial polymerization. The sulfonyl chloride solution containing the regulator consists of 0.15 wt% regulator (Ca(NTf2)2), 0.15 wt% sulfonyl chloride (1,3,6-naphthalenetrisulfonyl chloride), 1 wt% co-solvent (acetone), and the balance being an organic solvent (n-hexane); (2) The product obtained in step (1) is washed with an organic solvent (n-hexane); and placed in a constant temperature environment of 80°C for 5 min to obtain a polysulfonamide acid-resistant membrane with excellent separation performance.

[0024] See Figure 1 and Figure 2 .

[0025] Comparative example: The regulator (Ca(NTf2)2) in Example 1 was removed, and everything else was the same as in Example 1.

[0026] Example 2 A method for preparing a polysulfonamide acid-resistant membrane with excellent separation performance includes the following steps: (1) Immerse the polysulfone membrane in a 1 wt% aqueous solution of amine (triethylenetetramine) for 1 min, then remove it; then immerse it in a sulfonyl chloride solution containing a regulator for 3 min to undergo interfacial polymerization. The sulfonyl chloride solution containing the regulator consists of 0.01 wt% regulator (HNTf2), 0.01 wt% sulfonyl chloride (1,3,6-naphthalenetrisulfonyl chloride), 0.01 wt% co-solvent (toluene), and the balance being an organic solvent (cyclohexane). (2) The product obtained in step (1) is washed with an organic solvent (cyclohexane); and placed in a constant temperature environment of 60°C for 7 min to obtain a polysulfonamide acid-resistant membrane with excellent separation performance.

[0027] Example 3 A method for preparing a polysulfonamide acid-resistant membrane with excellent separation performance includes the following steps: (1) Immerse the polysulfone film in an aqueous solution of 4 wt% amine (tris(2-aminoethyl)amine) for 7 min, then remove it; then immerse it in a sulfonyl chloride solution containing a regulator for 7 min to undergo interfacial polymerization. The sulfonyl chloride solution containing the regulator consists of 0.3 wt% regulator (LiNTf2), 2 wt% sulfonyl chloride (1,3,5-benzenetrisulfonyl chloride), 2 wt% co-solvent (a mixture of acetone and toluene in a 1:1 mass ratio, or xylene, tetrahydrofuran, N,N-dimethylformamide or dimethyl sulfoxide), and the balance being an organic solvent (cyclopentane, or n-heptane or Isopar). (2) The product obtained in step (1) is washed with an organic solvent (cyclopentane, or n-heptane or Isopar can also be used); and placed in a constant temperature environment of 100°C for 1 min to obtain a polysulfonamide acid-resistant membrane with excellent separation performance.

[0028] Table 1 shows the retention effect of the polysulfonamide acid-resistant membranes with excellent separation performance prepared in each example on MgSO4. The test conditions are: cross-flow test, single salt aqueous solution of 2000 ppm, 25℃, 1 MPa.

[0029] Table 1

[0030] Table 2 shows the retention effect of the polysulfonamide acid-resistant membranes with excellent separation performance prepared in each example on MgSO4 after soaking in H2SO4 aqueous solution at pH = 1 at 60°C for 24 hours. The test conditions are: cross-flow test, single salt aqueous solution of 2000ppm, 25°C, 1MPa.

[0031] Table 2

[0032] By replacing the polysulfone membranes of the previous embodiments with polyethersulfone membranes, and otherwise remaining the same as in the previous embodiments, acid-resistant polysulfonamide membranes with excellent separation performance were prepared, exhibiting high crosslinking degree and smooth surface. The rejection rate for 2000 ppm MgSO4 was similar to that of the corresponding embodiments.

Claims

1. A method for preparing a polysulfonamide acid-resistant membrane with excellent separation performance, characterized in that... Includes the following steps: (1) Immerse the porous support membrane in an aqueous amine solution with a concentration of 1wt%-4wt% for 1-7 min, then remove it; then immerse it in a sulfonyl chloride solution containing a regulator for 3-7 min to allow interfacial polymerization to occur. The sulfonyl chloride solution containing the regulator consists of 0.01wt%-0.3wt% regulator, 0.01wt%-2wt% sulfonyl chloride, 0.01wt%-2wt% co-solvent, and the balance being an organic solvent; the regulator is HNTf2, LiNTf2, or Ca(NTf2)2; (2) The product obtained in step (1) is washed with an organic solvent and placed in a constant temperature environment of 60-100℃ for 1 min-7 min to obtain a polysulfonamide acid-resistant membrane with excellent separation performance.

2. The preparation method according to claim 1, characterized in that: The porous support membrane is a polysulfone membrane or a polyethersulfone membrane.

3. The preparation method according to claim 1, characterized in that: The amine is tri(2-aminoethyl)amine, triethylenetetramine, or tetraethylenepentamine.

4. The preparation method according to claim 1, characterized in that: The sulfonyl chloride is 1,3,6-naphthalenetrisulfonyl chloride or 1,3,5-benzenetrisulfonyl chloride.

5. The preparation method according to claim 1, characterized in that: The co-solvent is at least one selected from acetone, toluene, xylene, tetrahydrofuran, N,N-dimethylformamide, and dimethyl sulfoxide.

6. The preparation method according to claim 1, characterized in that: The organic solvent in step (1) is n-hexane, cyclohexane, cyclopentane, n-heptane, or Isopar.

7. The preparation method according to claim 1, characterized in that: The organic solvent in step (2) is n-hexane, cyclohexane, cyclopentane, n-heptane, or Isopar.

8. A polysulfonamide acid-resistant membrane with excellent separation performance prepared by the preparation method according to any one of claims 1-7.

9. The application of the polysulfonamide acid-resistant membrane with excellent separation performance as described in claim 8 in the treatment of acidic wastewater.

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