Modified polyisophthaloyl metaphenylene diamine membrane with oil-water separation performance as well as preparation method and application of modified polyisophthaloyl metaphenylene diamine membrane

Abstract

The invention relates to a modified polyisophthaloyl metaphenylene diamine membrane with oil-water separation performance as well as a preparation method and application thereof, the preparation method comprises the following steps: S1, sequentially adding triethanolamine, hexadecyl trimethyl ammonium bromide, sodium salicylate and tetraethoxysilane into deionized water, and mixing to prepare silicon dioxide particles; s2, mixing the silicon dioxide particles with tannic acid and polyethyleneimine to prepare tannic acid and polyethyleneimine modified silicon dioxide particles; s3, mixing the silicon dioxide particles modified by the tannic acid and the polyethyleneimine with polyisophthaloyl metaphenylene diamine to prepare a membrane casting solution; and S4, blade-coating a substrate with the membrane casting solution to obtain the modified polyisophthaloyl metaphenylene diamine membrane. Compared with the prior art, the preparation process is simple, the stability of the production process is good, and the prepared SiO2 (at) TA-PEI modified PMIA membrane is high in water flux, good in oil-water emulsion interception effect and capable of effectively separating oil-water emulsion and has potential application value in the aspect of oil wastewater treatment.

Description

Technical Field

[0001] The invention relates to the technical field of membrane separation, in particular to a modified polyisophthalamide-metaphenylene diamine membrane with oil-water separation performance, and a preparation method and application thereof. Background Art

[0002] Oily wastewater is an important area of ​​industrial and domestic wastewater treatment. Among various oil-containing forms, oil-water emulsions (especially emulsions stabilized by surfactants) are the most difficult to separate due to their excellent stability and tiny droplet size (<20μm). Compared with traditional degreasing, flotation and chemical flocculation separation methods, membrane separation technology is regarded as a promising method for oil-water emulsion separation due to its advantages of high separation efficiency, low cost, easy operation and no secondary pollution.

[0003] Poly(m-phenylene isophthalamide) (PMIA) membrane is a synthetic high-performance fiber with good thermal stability, chemical corrosion resistance and excellent mechanical properties. Due to the presence of a large number of amide groups in the molecular structure of PMIA membrane, it has a high surface free energy, so it is considered to be an excellent hydrophilic membrane material. The "hydration layer" on the surface of the hydrophilic membrane can effectively alleviate oil pollution in the oil-water separation process and achieve a good separation effect. Chinese patent CN107158960A discloses a method for preparing a high-throughput and anti-pollution poly(m-phenylene isophthalamide) nanofiltration membrane, which synergizes graphene oxide and sulfonated polyetheretherketone to improve the flux and anti-pollution performance of the poly(m-phenylene isophthalamide) nanofiltration membrane, but it is still difficult to solve the problem of difficult separation of oil-water emulsions. Summary of the invention

[0004] The purpose of the present invention is to overcome the defects of the above-mentioned prior art and provide a modified poly(m-phenylene isophthalamide) membrane with oil-water separation performance and its preparation method and application, so as to solve the problem that oil-water emulsion is difficult to separate.

[0005] The purpose of the present invention can be achieved by the following technical solutions:

[0006] In one aspect, the present invention provides a method for preparing a modified poly(m-phenylene isophthalamide) membrane having oil-water separation performance, comprising the following steps:

[0007] S1, triethanolamine (TEA), hexadecyltrimethylammonium bromide (CTAB), sodium salicylate (NaSal), and tetraethyl orthosilicate (TEOS) are sequentially added to deionized water, mixed, and stirred evenly, then centrifuged, the upper clear liquid is removed, the lower precipitate is taken, and finally the precipitate is calcined to obtain silicon dioxide (SiO2) particles;

[0008] S2, mixing the SiO2 particles obtained in S1 with tannic acid (TA) and polyethyleneimine (PEI), stirring with ultrasound, and then centrifuging, removing the supernatant, taking the lower precipitate, and finally vacuum drying the precipitate to obtain SiO2@TA-PEI particles;

[0009] S3, mixing the SiO2@TA-PEI particles prepared in S2 and poly(m-phenylene isophthalamide) (PMIA) to prepare a casting solution;

[0010] S4. Smear the casting solution on the substrate, and then place it in a gel bath for phase separation to obtain a modified PMIA film containing SiO2@TA-PEI particles.

[0011] Furthermore, in S1, the mass ratio of triethanolamine, hexadecyltrimethylammonium bromide, sodium salicylate and ethyl orthosilicate is (0.1-3):(0.1-10):(0.1-10):(20-30).

[0012] Preferably, in S1, the mass ratio of triethanolamine, hexadecyltrimethylammonium bromide, sodium salicylate and ethyl orthosilicate is (0.3-0.5):(1.5-2.5):3:(23-28).

[0013] Furthermore, in S1, the calcination temperature is 400-600° C., and the calcination time is 1.5-20 hours.

[0014] Furthermore, in S1, the stirring method is magnetic stirring.

[0015] Furthermore, in S2, the mass ratio of the silica particles, tannic acid and polyethyleneimine is (0.1-10):(0.1-10):(0.1-10).

[0016] Preferably, in S2, the mass ratio of the silicon dioxide particles, tannic acid and polyethyleneimine is (1-1.2): (1.8-2): (1.6-2).

[0017] Furthermore, in S2, the centrifugal speed is 5000-8000 rpm.

[0018] Furthermore, in S2, the vacuum drying temperature is 40-100°C.

[0019] Furthermore, in S3, the process of preparing the casting solution is specifically as follows: adding SiO2@TA-PEI particles, co-solvent and PMIA to N,N-dimethylacetamide (DMAC) and stirring evenly to obtain the casting solution.

[0020] Furthermore, in S3, the mass ratio of SiO2@TA-PEI particles, co-solvent and PMIA is (0.1~2):(0.1~5):(15~25).

[0021] Preferably, in S3, the mass ratio of SiO2@TA-PEI particles, co-solvent and PMIA is (0.1-0.5):2:(9-10).

[0022] Furthermore, in S3, the co-solvent is lithium chloride.

[0023] Furthermore, in S3, the stirring temperature is 30 to 80° C., and the stirring time is 8 to 48 hours.

[0024] Furthermore, in S4, the casting solution is coated on the substrate to a thickness of 100 to 300 μm.

[0025] Furthermore, in S4, the gel bath is carried out in deionized water, and the temperature of the gel bath is 10-40°C.

[0026] On the other hand, the present invention also provides a modified poly(m-phenylene isophthalamide) membrane having oil-water separation performance, which is prepared by the above-mentioned preparation method.

[0027] On the other hand, the present invention also provides an application of a modified poly(m-phenylene isophthalamide) membrane having oil-water separation performance.

[0028] Specifically, it can be used in the field of oil-water separation of oily wastewater.

[0029] Compared with the prior art, the present invention has the following beneficial effects:

[0030] (1) The method for preparing SiO2@TA-PEI modified PMIA membrane of the present invention is simple and easy to operate, has a short process cycle, does not require energy consumption, has low cost, and has good production process stability.

[0031] (2) The SiO2@TA-PEI modified PMIA membrane prepared in the present invention not only has good permeability, but also has a pure water flux of up to 330 L·(h -1 ·m -2 ), and after being immersed in common solvents for 12 hours, it can still maintain the oil-water separation effect, showing excellent stability. In addition, the membrane also has good hydrophilicity and anti-pollution properties, and the contact angle measured in the air is 37°, which makes it difficult for oil droplets to adhere to the membrane surface, thereby improving the separation efficiency of oil-water emulsion to more than 95%. Therefore, the membrane has important application potential in oil wastewater treatment, can effectively separate oil-water emulsions, and provides an efficient and stable solution for oil-water separation technology. BRIEF DESCRIPTION OF THE DRAWINGS

[0032] Figure 1 This is a SEM image of SiO2@TA-PEI prepared in Example 1 of the present invention;

[0033] Figure 2 This is a physical comparison diagram of the oil-water emulsion before and after separation in Example 1 of the present invention;

[0034] Figure 3 The microscopic comparison diagram of the oil-water emulsion before and after separation of Example 1 of the present invention is as follows: (a) before separation, (b) after separation. DETAILED DESCRIPTION

[0035] The present invention is described in detail below in conjunction with the accompanying drawings and specific embodiments. Any features such as preparation means, materials, structures or composition ratios not clearly described in this technical solution are regarded as common technical features disclosed in the prior art.

[0036] Table 1 shows the specifications and manufacturers of materials and reagents in the following examples. The rest of the raw materials or processing techniques, unless otherwise specified, are conventional commercially available raw materials or conventional techniques in the art.

[0037] Table 1 Materials and reagents

[0038]

[0039] The permeability and retention properties of the modified PMIA membrane were studied using pressurized membrane separation technology. That is, under a certain pressure, small molecular solutes and solvents will pass through a membrane with a certain pore size, while large molecular solutes will not pass through and will be retained.

[0040] The oil component (n-hexadecane, n-heptane, n-hexane, cyclohexane), deionized water and surfactant (Tween80) were blended to prepare an oil-water emulsion. The volume ratio of water to oil component was 99:1, and the concentration of Tween80 was 10 mg / L after dilution 10 times. Ultrasonic dispersion was performed at room temperature for 30 min and stirring was performed for 8 h to obtain a stable oil-water emulsion. Subsequently, a specific volume of the oil-water emulsion was poured into a suction filtration device. The separation process started after the system pressure reached 0.1 MPa and was operated at room temperature.

[0041] Finally, the separation efficiency R is calculated by formula (1), and the permeation flux J (L·m -2 ·h -1 ),as follows:

[0042]

[0043] Where R is the separation efficiency, M1 and M2 are the weight of the filtered permeate and the mass of the feed solution (g), respectively.

[0044]

[0045] Where Q is the permeate volume, T is the time it takes for the oil-water emulsion to pass through the membrane, and A is the effective filtration area of ​​the sample

[0046] Example 1

[0047] This embodiment is used to prepare a modified poly(m-phenylene isophthalamide) membrane having oil-water separation performance, and the specific preparation method is as follows:

[0048] S1. At room temperature, 0.3 g TEA was added to 100 mL deionized water and magnetically stirred at room temperature for 2.5 h. Then 2.5 g CTAB and 3 g NaSal were added to the solution and the mixture was stirred for another 2.5 h. Then 30 mL TEOS was added to the above solution and stirred for another 2.5 h at 80 ° C. and allowed to stand for 30 min. The centrifuge speed was 8000 rpm for 30 min. The upper clear liquid was removed and the lower precipitate was taken. The precipitate was dried at 50 ° C for 48 h and finally calcined at 550 ° C for 5 h in a muffle furnace to obtain SiO2 particles.

[0049] S2. Weigh 1.8g of TA and place it in a 250mL beaker, add 120mL of deionized water, stir for 1.5h to completely dissolve TA, and obtain solution A; take 1g of SiO2 particles and place it in 80mL of deionized water, then pour it into solution A, and stir for 1.5h to obtain TA-SiO2 suspension; weigh 1.6g of PEI, pour it into 40mL of deionized water, stir for 1.5h, and then quickly pour in hydrochloric acid solution, adjust the pH to 8, and then stir for 2h. Pour the obtained solution into the above TA-SiO2 suspension and continue stirring for 12h, then let it stand for 30min. Centrifuge speed 8000rpm, centrifuge for 25min, take the lower layer of precipitate, put the precipitate into a crucible, vacuum dry it in a 60℃ oven for 12h, and finally obtain SiO2@TA-PEI particles, which are ground into powder.

[0050] S3, dissolving 0.1 g SiO2@TA-PEI particles, 2 g lithium chloride, and 9.25 g PMIA in 80 mL DMAc, stirring at 80°C for 24 h until fully dissolved, to prepare a casting solution;

[0051] S4. Scrape the casting liquid onto a glass plate with a thickness of 250 μm, and then immerse the glass plate with the casting liquid into a coagulation bath composed of deionized water at 20°C for phase separation to obtain a modified PMIA membrane containing SiO2@TA-PEI particles, which is recorded as M1 membrane.

[0052] The water flux and oil-water emulsion rejection rate of the M1 membrane prepared in Example 1 were tested. The water flux was 330 L·(h -1 ·m-2 ), the oil-water separation performance of the M1 membrane was tested using 100 g of an oil-water emulsion (the volume ratio of oil to water was 1:9), and the oil retention rate was 95%.

[0053] Figure 1 This is the SEM image of SiO2@TA-PEI obtained in Example 1. It can be seen from the image that SiO2@TA-PEI is regular and uniform spherical particles with a particle diameter of less than 100 nm.

[0054] Figure 2 It is a comparison of the oil-water emulsion before and after interception. It can be seen from the figure that the modified PMIA membrane has a good interception effect. Therefore, the modification scheme significantly improves the hydrophilicity and oil-water separation ability of the PMIA membrane. The modified PMIA membrane has a good application prospect in the treatment of oily wastewater.

[0055] Figure 3 This is a microscopic comparison of the oil-water emulsion before and after separation in Example 1. The oil-water emulsion before and after interception was placed under an optical microscope and photographed. Figure 3 (a) is the microscopic image before separation. Figure 3 (b) is the microscopic picture after separation. It can be seen that the modified PMIA membrane can effectively intercept oil droplets, and there are almost no oil droplets in the liquid obtained after interception.

[0056] Example 2

[0057] This embodiment is used to prepare a modified poly(m-phenylene isophthalamide) membrane having oil-water separation performance, and the specific preparation method is as follows:

[0058] S1. At room temperature, 0.5 g TEA was added to 100 mL deionized water and magnetically stirred at room temperature for 2.5 h. Then 1.5 g CTAB and 3 g NaSal were added to the solution and the mixture was stirred for another 2.5 h. Then 25 mL TEOS was added to the above solution and stirred for another 2.5 h at 80 ° C. and allowed to stand for 30 min. The centrifuge speed was 8000 rpm for 30 min. The upper clear liquid was removed and the lower precipitate was taken. The precipitate was dried at 50 ° C for 48 h and finally calcined at 550 ° C for 5 h in a muffle furnace to obtain SiO2 particles.

[0059] S2. Weigh 1.8g of TA and place it in a 250mL beaker, add 120mL of deionized water, stir for 1.5h to completely dissolve TA, and obtain solution A; take 1g of SiO2 particles and place it in 80mL of deionized water, then pour it into solution A, and stir for 1.5h to obtain TA-SiO2 suspension; weigh 1.6g of PEI, pour it into 40mL of deionized water, stir for 1.5h, and then quickly pour in hydrochloric acid solution, adjust the pH to 8, and then stir for 2h. Pour the obtained solution into the above TA-SiO2 suspension and continue stirring for 12h, then let it stand for 30min. Centrifuge speed 8000rpm, centrifuge for 25min, take the lower layer of precipitate, put the precipitate into a crucible, vacuum dry it in a 60℃ oven for 12h, and finally obtain SiO2@TA-PEI particles, which are ground into powder.

[0060] S3, dissolving 0.1 g SiO2@TA-PEI particles, 2 g lithium chloride, and 9.25 g PMIA in 80 mL DMAc, stirring at 80°C for 24 h until fully dissolved, to prepare a casting solution;

[0061] S4. Scrape the casting liquid onto a glass plate with a thickness of 250 μm, and then immerse the glass plate with the casting liquid into a coagulation bath composed of deionized water at 20°C for phase separation to obtain a modified PMIA membrane containing SiO2@TA-PEI particles, which is recorded as M2 membrane.

[0062] The water flux of M2 is 298L·(h -1 ·m -2 ), the oil retention rate is 87%.

[0063] Example 3

[0064] This embodiment is used to prepare a modified poly(m-phenylene isophthalamide) membrane having oil-water separation performance, and the specific preparation method is as follows:

[0065] S1. At room temperature, 0.3 g TEA was added to 100 mL deionized water and magnetically stirred at room temperature for 2.5 h. Then 2.5 g CTAB and 3 g NaSal were added to the solution and the mixture was stirred for another 2.5 h. Then 30 mL TEOS was added to the above solution and stirred for another 2.5 h at 80 ° C. and allowed to stand for 30 min. The centrifuge speed was 8000 rpm for 30 min. The upper clear liquid was removed and the lower precipitate was taken. The precipitate was dried at 50 ° C for 48 h and finally calcined at 550 ° C for 5 h in a muffle furnace to obtain SiO2 particles.

[0066] S2. Weigh 2g of TA and place it in a 250mL beaker, add 120mL of deionized water, stir for 1.5h, dissolve TA completely, and obtain solution A; take 1.2g of SiO2 particles and place them in 80mL of deionized water, then pour them into solution A, stir for 1.5h to obtain TA-SiO2 suspension; weigh 2g of PEI, pour them into 50mL of deionized water, stir for 1.5h, quickly pour in hydrochloric acid solution, adjust pH to 8, then stir for 2h, pour the obtained solution into the above TA-SiO2 suspension, continue stirring for 12h, and let it stand for 30min. Centrifuge speed 8000rpm, centrifuge for 25min, take the lower layer of precipitate, put the precipitate into a crucible, vacuum dry it in a 60℃ oven for 12h, and finally obtain SiO2@TA-PEI particles, grind them into powder.

[0067] S3, dissolving 0.1 g SiO2@TA-PEI particles, 2 g lithium chloride, and 9.25 g PMIA in 80 mL DMAc, stirring at 80°C for 24 h until fully dissolved, to prepare a casting solution;

[0068] S4. Scrape the casting liquid onto a glass plate with a thickness of 250 μm, and then immerse the glass plate with the casting liquid into a coagulation bath composed of deionized water at 20°C for phase separation to obtain a modified PMIA membrane containing SiO2@TA-PEI particles, which is recorded as M3 membrane.

[0069] The water flux of M3 is 309L·(h -1 ·m -2 ), the oil retention rate is 91%.

[0070] Example 4

[0071] This embodiment is used to prepare a modified poly(m-phenylene isophthalamide) membrane having oil-water separation performance, and the specific preparation method is as follows:

[0072] S1. At room temperature, 0.3 g TEA was added to 100 mL deionized water and magnetically stirred at room temperature for 2.5 h. Then 2.5 g CTAB and 3 g NaSal were added to the solution and the mixture was stirred for another 2.5 h. Then 30 mL TEOS was added to the above solution and stirred for another 2.5 h at 80 ° C. and allowed to stand for 30 min. The centrifuge speed was 8000 rpm for 30 min. The upper clear liquid was removed and the lower precipitate was taken. The precipitate was dried at 50 ° C for 48 h and finally calcined at 550 ° C for 5 h in a muffle furnace to obtain SiO2 particles.

[0073] S2. Weigh 1.8g of TA and place it in a 250mL beaker, add 120mL of deionized water, stir for 1.5h to completely dissolve TA, and obtain solution A; take 1g of SiO2 particles and place it in 80mL of deionized water, then pour it into solution A, and stir for 1.5h to obtain TA-SiO2 suspension; weigh 1.6g of PEI, pour it into 40mL of deionized water, stir for 1.5h, and then quickly pour in hydrochloric acid solution, adjust the pH to 8, and then stir for 2h. Pour the obtained solution into the above TA-SiO2 suspension and continue stirring for 12h, then let it stand for 30min. Centrifuge speed 8000rpm, centrifuge for 25min, take the lower layer of precipitate, put the precipitate into a crucible, vacuum dry it in a 60℃ oven for 12h, and finally obtain SiO2@TA-PEI particles, which are ground into powder.

[0074] S3, dissolving 0.5 g SiO2@TA-PEI particles, 2 g lithium chloride, and 10 g PMIA in 80 mL DMAc, stirring at 80°C for 24 h until fully dissolved, to prepare a casting solution;

[0075] S4. The casting liquid was scraped onto a glass plate with a thickness of 250 μm, and the glass plate with the casting liquid was immersed in a coagulation bath composed of deionized water at 20°C for phase separation to obtain a modified PMIA membrane containing SiO2@TA-PEI particles, which was recorded as M4 membrane.

[0076] The water flux of M4 is 315L·(h -1 ·m -2 ), the oil retention rate is 92%.

[0077] Comparative Example 1

[0078] This embodiment is used to prepare a poly(m-phenylene isophthalamide) film without SiO2@TA-PEI particles. The specific preparation method is as follows:

[0079] S1. Dissolve 2 g lithium chloride and 9.25 g PMIA in 80 mL DMAc, and stir at 80° C. for 24 h until fully dissolved to prepare a casting solution;

[0080] S2. The casting liquid was scraped onto a glass plate with a thickness of 250 μm, and then the glass plate with the casting liquid was immersed in a coagulation bath composed of deionized water at 20° C. for phase separation to obtain an unmodified PMIA membrane, which was recorded as M0 membrane.

[0081] The water flux of M0 is 276L·(h -1 ·m -2 ), the oil retention rate is 20%.

[0082] It can be seen from the test results in Examples 1-4 and Comparative Example 1 that compared with the unmodified PMIA membrane, the modified PMIA membrane containing SiO2@TA-PEI particles exhibits superior permeability and better water-oil separation performance.

[0083] The above description of the embodiments is to facilitate the understanding and use of the invention by those skilled in the art. It is obvious that those skilled in the art can easily make various modifications to these embodiments and apply the general principles described herein to other embodiments without creative work. Therefore, the present invention is not limited to the above embodiments, and improvements and modifications made by those skilled in the art based on the disclosure of the present invention without departing from the scope of the present invention should be within the scope of protection of the present invention.

Claims

1. A method for preparing a modified poly(m-phenylene isophthalamide) membrane having oil-water separation performance, characterized in that: The steps include: S1, adding triethanolamine, hexadecyltrimethylammonium bromide, sodium salicylate and ethyl orthosilicate into deionized water in sequence, mixing, and calcining to obtain silicon dioxide particles; S2, mixing the silica particles prepared in S1 with tannic acid and polyethyleneimine to prepare silica particles modified with tannic acid and polyethyleneimine; S3, mixing the tannic acid and polyethyleneimine-modified silica particles obtained in S2 with poly(m-phenylene isophthalamide) to prepare a casting solution; S4, coating the casting solution on the substrate by scraping, and then placing the substrate in a gel bath for phase separation to obtain a modified poly(m-phenylene isophthalamide) film.

2. The method for preparing a modified poly(m-phenylene isophthalamide) membrane having oil-water separation performance according to claim 1, characterized in that: In S1, the mass ratio of triethanolamine, hexadecyltrimethylammonium bromide, sodium salicylate and tetraethyl orthosilicate is (0.1-3):(0.1-10):(0.1-10):(20-30), the calcination temperature is 400-600° C., and the calcination time is 1.5-20 h.

3. The method for preparing a modified poly(m-phenylene isophthalamide) membrane having oil-water separation performance according to claim 1, characterized in that: In S2, the mass ratio of the silicon dioxide particles, tannic acid and polyethyleneimine is (0.1-10):(0.1-10):(0.1-10).

4. The method for preparing a modified poly(m-phenylene isophthalamide) membrane having oil-water separation performance according to claim 1, characterized in that: In S3, the process of preparing the casting solution is specifically as follows: adding tannic acid and polyethyleneimine-modified silica particles, a cosolvent and poly(m-phenylene isophthalamide) to N,N-dimethylacetamide and stirring evenly to obtain the casting solution.

5. The method for preparing a modified poly(m-phenylene isophthalamide) membrane having oil-water separation performance according to claim 4, characterized in that: The mass ratio of the tannic acid and polyethyleneimine modified silica particles, the cosolvent and poly(m-phenylene isophthalamide) is (0.1-2): (0.1-5): (15-25), and the cosolvent is lithium chloride.

6. The method for preparing a modified poly(m-phenylene isophthalamide) membrane having oil-water separation performance according to claim 4, characterized in that: The stirring temperature is 30-80° C., and the stirring time is 8-48 hours.

7. The method for preparing a modified poly(m-phenylene isophthalamide) membrane having oil-water separation performance according to claim 1, characterized in that: In S4, the casting solution is coated on the substrate to a thickness of 100 to 300 μm.

8. The method for preparing a modified poly(m-phenylene isophthalamide) membrane having oil-water separation performance according to claim 1, characterized in that: In S4, the gel bath is carried out in deionized water, and the temperature of the gel bath is 10-40°C.

9. A modified poly(m-phenylene isophthalamide) membrane having oil-water separation performance, characterized in that: It is prepared based on the preparation method according to any one of claims 1 to 8.

10. Use of the modified poly(m-phenylene isophthalamide) membrane having oil-water separation performance as claimed in claim 9 in oil-water separation.

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