Ceramic-lined polysulfone nanofiltration membrane and preparation method thereof

Abstract

The invention relates to the technical field of membrane separation, and discloses a ceramic-lined polysulfone nanofiltration membrane and a preparation method thereof, the preparation method comprises the following steps: step S1, preparing a water phase solution: dissolving PSF and NMP in deionized water, and adjusting the pH value to 11-13; step S2, preparing an oil phase solution, namely dissolving 1, 3-phenylenediamine, CaSO4, ZnO, chalk and rosin into an ethyl cyclohexane solution together, uniformly stirring, and adding the dissolved 1, 3, 5-benzoyl chloride into an oil phase tank; s3, base membrane dipping: sequentially dipping the ceramic base membrane into the water phase solution and the oil phase solution; step S4, post-treatment: sequentially putting into citric acid, pure water, NaClO, pure water, a NaHSO3 solution and glycerol for dipping; and S5, drying and curing. The ceramic material is used for replacing polyester non-woven fabric to serve as a nanofiltration membrane base material, meanwhile, the ceramic material is combined with the polysulfone material to form the composite nanofiltration membrane, the composite nanofiltration membrane has good chemical stability and mechanical strength, the service life can be effectively prolonged, and the composite nanofiltration membrane further has high separation efficiency and anti-pollution performance.

Description

Technical Field

[0001] The present invention relates to the technical field of membrane separation, and in particular to a ceramic-lined polysulfone nanofiltration membrane and a preparation method thereof. Background Art

[0002] As a separation technology between ultrafiltration and reverse osmosis, the core function of the nanofiltration membrane is to intercept organic substances and polyvalent ions with a molecular weight of 200-1000. Traditional nanofiltration membrane substrates mostly use polyester non-woven fabrics, which have the following defects:

[0003] 1. The membrane flux is limited, and the separation efficiency decreases significantly with the operation time;

[0004] 2. Poor chemical stability, prone to hydrolysis or oxidative degradation in strong acid or strong base environments, and short service life;

[0005] 3. Insufficient mechanical strength, prone to membrane structure damage under long-term high-pressure operation;

[0006] 4. Prone to adsorb oily pollutants, requiring frequent chemical cleaning, increasing the operation and maintenance costs.

[0007] Polysulfone (PSF) materials are widely used as membrane materials due to their high glass transition temperature (195°C) and strong chemical corrosion resistance. However, the defects of traditional polyester non-woven fabric substrates limit the potential of polysulfone membranes.

[0008] Based on this, the present application provides a ceramic-lined polysulfone nanofiltration membrane with high flux, good chemical stability, high mechanical strength, and strong anti-pollution performance and a preparation method thereof to solve the above problems. Summary of the Invention

[0009] The present invention aims to solve the technical problems existing in the prior art. To this end, the present invention provides a ceramic-lined polysulfone nanofiltration membrane with high flux, good chemical stability, good mechanical properties, and strong anti-pollution performance and a preparation method thereof.

[0010] The technical solution adopted by the present invention to solve its technical problems is:

[0011] In the first aspect, a preparation method of a ceramic-lined polysulfone nanofiltration membrane is provided, including the following steps:

[0012] Step S1, preparing an aqueous solution: Dissolve polysulfone and N-methyl-2-pyrrolidone in deionized water in an aqueous phase tank, adjust the pH to 11-13 with NaOH, and stir for 10-15 minutes to form an aqueous solution;

[0013] Step S2, preparing an oil phase solution: In an oil phase tank, 1,3-phenylenediamine, CaSO 4, ZnO, chalk, and rosin are dissolved in an ethylcyclohexane solution and stirred evenly. The dissolved 1,3,5-benzenetricarbonyl chloride is added to the oil-phase tank, and then stirred for 10 minutes to form an oil-phase solution;

[0014] Step S3, base film impregnation: The ceramic base film is successively immersed in the water-phase tank and the oil-phase tank, staying for 3 - 5 minutes each. After each impregnation, the excess liquid droplets on the surface are scraped off using a flexible rubber sheet, and then placed in a fume hood to air dry;

[0015] Step S4, post-treatment: The ceramic base film treated in Step S3 is successively immersed in citric acid, pure water, NaClO, pure water, NaHSO 3 solution, and glycerol;

[0016] Step S5, drying and curing: The membrane sheet treated in Step S4 is placed in a forced-air drying oven and dried at 80 °C for 5 minutes to form a finished ceramic-supported polysulfone composite nanofiltration membrane.

[0017] In some alternative embodiments, in Step S1, the raw materials are prepared according to the following mass percentages: polysulfone 3% - 5%, N-methyl-2-pyrrolidone 0.5% - 1.0%, and deionized water as the balance.

[0018] In some alternative embodiments, in Step S2, the raw materials are prepared according to the following mass percentages: 1,3-phenylenediamine 5% - 8%, CaSO 4 0.5 - 1.5%, ZnO 0.5 - 1.5%, chalk 0.5 - 1.0%, rosin 0.3 - 0.5%, 1,3,5-benzenetricarbonyl chloride 0.10% - 0.15%, and ethylcyclohexane as the balance.

[0019] In some alternative embodiments, in Step S3, the ceramic base film is made of α-alumina ceramic, with a thickness of 200 μm - 300 μm and a porosity of 60% - 80%.

[0020] In some alternative embodiments, in Step S4, the specific steps are as follows: The membrane sheet is immersed in an 80 °C citric acid solution for 4 minutes, taken out and placed in pure water for 2 minutes; then the membrane sheet is placed in an NaClO solution for 1 minute, taken out and placed in pure water for 1 minute; then the membrane sheet is placed in a NaHSO 3 solution for 1 minute; finally, the membrane sheet is immersed in glycerol for 1 minute.

[0021] In a second aspect, there is provided a ceramic-supported polysulfone nanofiltration membrane prepared by the method for preparing a ceramic-supported polysulfone nanofiltration membrane as described above, having a desalination rate ≥ 99%, a water flux ≥ 45 L / (m 2 ·h), a heat resistance ≥ 150 °C, an acid and alkali resistance range of pH 2 - 12, and a service life ≥ 5 years.

[0022] Compared with the prior art, the beneficial effects of the present invention are as follows:

[0023] In the present invention, a ceramic material is used to replace the polyester non-woven fabric as the substrate of the nanofiltration membrane, and at the same time, it is combined with a polysulfone material to form a composite nanofiltration membrane, which has good chemical stability and mechanical strength, can effectively improve the service life, and also has high separation efficiency and anti-pollution performance. Detailed implementation manners

[0024] It should be understood that the specific embodiments described herein are only used to explain the present invention and are not used to limit the present invention.

[0025] The technical solutions in the embodiments of the present invention will be clearly and completely described below. Obviously, the described embodiments are only a part of the embodiments of the present invention, rather than all of the embodiments. All other embodiments obtained by those of ordinary skill in the art based on the embodiments of the present invention without creative efforts shall fall within the protection scope of the present invention.

[0026] Embodiment 1

[0027] This embodiment provides a method for preparing a nanofiltration membrane with a ceramic-lined polysulfone, which includes the following steps:

[0028] Step S1, preparing an aqueous solution: Dissolve 3 Kg of polysulfone (PSF) and 0.5 Kg of N-methyl-2-pyrrolidone (NMP) in 96.5 Kg of deionized water in an aqueous phase tank, adjust the pH to about 12 with NaOH, and stir at 200 rpm for 10 minutes to form an aqueous solution;

[0029] Step S2, preparing an oil phase solution: Dissolve 8 Kg of 1,3-phenylenediamine, 1 Kg of CaSO 4 , 1 Kg of ZnO, 0.8 Kg of chalk, and 0.35 Kg of rosin in 88.7 Kg of ethyl cyclohexane solution, stir evenly, add 0.15 Kg of dissolved 1,3,5-benzenetricarbonyl chloride (TMC) to the oil phase tank, and then stir for 10 minutes to form an oil phase solution;

[0030] Step S3, impregnating the base membrane: Immerse the ceramic base membrane into the aqueous phase tank and the oil phase tank in sequence, stay in the aqueous phase tank and the oil phase tank for 3-5 minutes respectively, scrape off the excess liquid droplets on the surface with a flexible rubber plate after each impregnation, and then place it in a fume hood, observe the surface of the membrane sheet to dry and then take it out; The ceramic base membrane is preferably made of α-aluminum oxide ceramic, with a thickness of 200 μm - 300 μm and a porosity of 60% - 80%. By using the advantages of high porosity, hydrophilic and oleophobic, good chemical stability, large flux, high temperature resistance, and good wear resistance of the ceramic material, the performance, quality, and service life of the nanofiltration membrane are improved.

[0031] Step S4, Post-treatment: The ceramic-based membrane after being treated in Step S3 is successively immersed in citric acid, pure water, NaClO, pure water, NaHSO 3 solution, and glycerol, specifically as follows:

[0032] Immerse the membrane in a citric acid solution at 80 °C for 4 minutes, take it out and put it in pure water for 2 minutes;

[0033] Then immerse the membrane in the NaClO solution for 1 minute, take it out and put it in pure water for 1 minute;

[0034] Then immerse the membrane in the NaHSO 3 solution for 1 minute;

[0035] Finally, immerse the membrane in glycerol for 1 minute.

[0036] Step S5, Drying and Curing: Place the membrane treated in Step S4 in a forced-air drying oven and dry it at 80 °C for 5 minutes to form a finished composite nanofiltration membrane of ceramic-lined polysulfone.

[0037] In this embodiment, a high-porosity ceramic substrate is compounded with polysulfone, solving the mechanical and chemical performance shortcomings of traditional substrates; at the same time, through step-by-step impregnation and gradient post-treatment, the bonding strength between the ceramic and polysulfone is improved.

[0038] Test the nanofiltration membrane of ceramic-lined polysulfone prepared by the above preparation method. The test standard: "Test Method for Spiral Wound Reverse Osmosis Membrane Elements" HY / T 107-2017. The test conditions: The test solution is a sodium chloride solution with a concentration of 2.03×10³ mg / L, the test temperature is 27.8 °C, and the test pressure is 1.591 MPa.

[0039] Test results: Desalination rate: 99.7% (conductivity meter), water flux: 48.1 L / (m 2 ·h), water production: 43.9 m 3 / d.

[0040] Chemical stability test: Immerse in 10% HCl or 10% NaOH for 30 days, and the membrane structure is intact without damage.

[0041] Thermal resistance test: Continuously operate at 150 °C for 1000 hours, and the flux decay rate <5%.

[0042] The above are only embodiments of the present invention, and do not limit the patent scope of the present invention accordingly. Any equivalent structure or equivalent process transformation made by using the content of the specification of the present invention, or directly or indirectly applied in other related technical fields, shall be equally included in the patent protection scope of the present invention.

Claims

1. A method for preparing a ceramic-lined polysulfone nanofiltration membrane, characterized in that: The following steps are involved: Step S1, preparing an aqueous phase solution: dissolving polysulfone and N-methyl-2-pyrrolidone in deionized water in an aqueous phase tank, adjusting the pH to 11-13 with NaOH, and stirring for 10-15 minutes to form an aqueous phase solution; Step S2, preparing an oil phase solution: dissolving 1,3-phenylenediamine, CaSO4, ZnO, chalk and rosin in an ethylcyclohexane solution in an oil phase tank, stirring evenly, adding the dissolved 1,3,5-benzenetricarboxylic acid chloride to the oil phase tank, and stirring for 10 minutes to form an oil phase solution; Step S3, base film immersion: immerse the ceramic base film in the water phase tank and the oil phase tank in turn, and stay for 3 to 5 minutes respectively. After each immersion step, use a flexible rubber sheet to scrape off excess droplets on the surface, and then place it in a fume hood to air dry; Step S4, post-treatment: immersing the ceramic base film treated in step S3 in citric acid, pure water, NaClO, pure water, NaHSO3 solution, and glycerol in sequence; Step S5, drying and curing: placing the membrane sheet treated in step S4 in a forced air drying oven and drying at 80° C. for 5 minutes to form a finished composite nanofiltration membrane of ceramic lined polysulfone.

2. The preparation method according to claim 1, characterized in that: In step S1, the raw materials are prepared according to the following mass percentages: Polysulfone 3%-5%, N-methyl-2-pyrrolidone 0.5%-1.0%, and deionized water as the balance.

3. The preparation method according to claim 1, characterized in that: In step S2, the raw materials are prepared according to the following mass percentages: 1,3-phenylenediamine 5%-8%, CaSO4 0.5-1.5%, ZnO 0.5-1.5%, chalk 0.5-1.0%, rosin 0.3-0.5%, 1,3,5-benzenetricarboxylic acid chloride 0.10%-0.15%, and ethylcyclohexane as the balance.

4. The preparation method according to claim 1, characterized in that: In step S3, the ceramic base membrane is made of α-alumina ceramic with a thickness of 200 μm to 300 μm and a porosity of 60% to 80%.

5. The preparation method according to claim 1, characterized in that: In step S4, the specific steps are: soak the membrane in a 80°C citric acid solution for 4 minutes, take it out and put it in pure water for 2 minutes; then put the membrane in a NaClO solution for 1 minute, take it out and put it in pure water for 1 minute; then put the membrane in a NaHSO3 solution for 1 minute; finally, soak the membrane in glycerol for 1 minute.

6. A ceramic lined polysulfone nanofiltration membrane, characterized in that: The nanofiltration membrane is prepared by the preparation method according to any one of claims 1 to 5, wherein the desalination rate of the nanofiltration membrane is ≥ 99%, and the water flux is ≥ 45 L / (m 2 h), temperature resistance ≥150℃, acid and alkali resistance range pH 2~12, service life ≥5 years.