DE102017129204A1 - A ULTRAFILTRATION MEMBRANE AND METHOD FOR THE PRODUCTION THEREOF - Google Patents

Abstract

The present invention relates to a process for producing an ultrafiltration membrane having high mechanical properties. In the present invention, since the lignin having a high mechanical property is added to the molding membrane solution, the retention rate of the ultrafiltration membrane of the present invention is improved.

Description

TECHNICAL AREA

The present invention relates to an ultrafiltration membrane having high mechanical properties and its production process.

BACKGROUND

Due to the fact that the ultrafiltration membrane is exposed to pressure for a long time but has poor mechanical properties, currently the life of the ultrafiltration membrane is shortened and the ultrafiltration membrane in the membrane module needs to be replaced frequently.

Therefore, it is necessary to develop an ultrafiltration membrane capable of improving the mechanical properties of the ultrafiltration membrane.

SUMMARY OF THE INVENTION

An object of the present invention is to provide an ultrafiltration membrane having high mechanical properties and its production process.

The present invention relates to a process for producing an ultrafiltration membrane having high mechanical properties. In the present invention, since the lignin having high mechanical properties is added to the molding membrane solution, the retention rate of the ultrafiltration membrane of the present invention is improved.

DETAILED DESCRIPTION OF THE EMBODIMENTS

example 1

• Step 1: polyethersulfone 16g, lignin 8g and polyvinylpyrrolidone 0.8g are placed in a 3-neck flask;
• Step 2: then 50 g of N, N-dimethylacetamide is added to the 3-necked flask to obtain a mixture, the mixture is stirred at 65 ° C for 5 hours;
• Step 3: Allow to defoam for 8 hours in an environment with a temperature of 20 ° C and a humidity of 20% to obtain a uniform, foam-free casting membrane solution;
• Step 4: the cast membrane solution is poured onto a glass substrate, and the cast membrane solution on the glass substrate is applied with a membrane applicator to obtain a membrane in the liquid state having a thickness of 200 μm;
• Step 5: the glass substrate with the membrane formed thereon in the liquid state is placed in an environment with a temperature of 20 ° C and a humidity of 20% for volatilization for 15 seconds;
• Step 6: The glass substrate having the membrane formed thereon in the liquid state is placed in deionized water to solidify the membrane in a liquid state into a solid-state membrane; and
• Step 7: The solid-state membrane is taken out of the deionized water, air-dried and placed in a drying oven for 10 minutes to obtain the ultrafiltration membrane.

For the reference example, all the experimental conditions are the same as those of Embodiment 1, except that the lignin is not added. Table 1 information example 1 Example 2 Example 3 Example 4 Example 5 Example 6 Example 7 Example 8 Example 9 Example 10 reference The mass concentration of polyethersulfone (%) 32 20 50 32 32 32 32 32 32 32 32 The mass ratio of lignin and Polyethersu lfon 0.5: 1 0.5: 1 0.5: 1 0.1: 1 1: 1 0.5: 1 0.5: 1 0.5: 1 0.5: 1 0.5: 1 - The mass ratio of PVP and Polyethersu lfon 0.05: 1 0.05: 1 0.05: 1 0.05: 1 0.05: 1 0.01: 1 0.1: 1 0.05: 1 0.05: 1 0.05: 1 0.05: 1 The first temperature (° C) 65 65 65 65 65 65 65 65 50 90 65 The second temperature (° C) 20 20 20 20 20 20 20 15 20 20 20 The third temperature (° C) 20 20 20 20 20 20 20 25 20 20 20 The first humidity (%) 20 20 20 20 20 20 20 10 20 20 20 The second humidity (%) 20 20 20 20 20 20 20 30 20 20 20 The first period (h) 8th 8th 8th 8th 8th 8th 8th 8th 10 6 8th The second period (s) 15 15 15 15 15 15 15 15 10 120 15 The third period (min) 10 10 10 10 10 10 10 10 5 60 10

In Examples 1-3, all experimental conditions are the same except that the mass concentrations of polyethersulfone are 32%, 20% and 50%, respectively.

In Examples 1, 4 and 5, all experimental conditions are the same except that the mass ratios between lignin and polyethersulfone are 0.5: 1, 0.1: 1 and 1: 1, respectively.

In Examples 1, 6 and 7, all experimental conditions are the same except that the mass ratios between PVP and polyethersulfone are 0.05: 1, 0.01: 1 and 0.1: 1, respectively.

In Examples 1 and 8, all experimental conditions are the same except that in Example 1, the second and third temperatures, the first and second humidity are 20 ° C, 20 ° C, 20% and 20%, respectively; however, in Example 8, it is 15 ° C, 25 ° C, 10% and 30%, respectively. That is, the environments for defoaming and for forming the solid-state membrane are different.

In Examples 1, 9, and 10, all experimental conditions are the same except that the first temperature, the first, second, and third periods are different from each other, i. H. the temperature for the preparation of the casting membrane solution, the time for the preparation of the casting membrane solution, the time for volatilization of the applied liquid membrane and the time for drying the membrane sample are different.

Test Example 1

The mechanical properties of the membranes prepared in Examples 1-10 and Comparative Example are measured and compared, the measurement results are shown in Table 2.

• Testinstrument: Papier- und Kartonzugfestigkeitsprüfgerät ZL-100A

Test of mechanical properties:

• Test instrument: paper and cardboard tensile tester ZL-100A

• Zuerst wird eine zu testende Membranprobe in eine an das Prüfgerät angepasste Form geschnitten und ein Skalenabstand wird mit zwei Markierungslinien markiert;
• Zweitens wird die zugeschnittene Membranprobe in den Halter des Prüfgeräts gelegt und vorsichtig auf eine symmetrische Position eingestellt, um zu ermöglichen, dass die Dehnkraft gleichmäßig auf den Querschnitt der Membranprobe verteilt wird;
• Schließlich wird das Prüfgerät gestartet, und die maximale Kraft (mit einer Abweichung von ± 1%), bei der die Membranprobe reißt, sowie der Abstand (mit einer Abweichung von ± 1,25 mm) zwischen den Innenseiten der beiden Markierungslinien werden erfasst.

Test steps:

• First, a membrane sample to be tested is cut into a mold adapted to the tester and a scale interval is marked with two marking lines;
• Second, the tailored membrane sample is placed in the holder of the tester and carefully adjusted to a symmetrical position to allow the stretching force to be evenly distributed across the cross-section of the membrane sample;
• Finally, the tester is started and the maximum force (with a deviation of ± 1%) at which the membrane sample breaks and the distance (with a deviation of ± 1.25 mm) between the insides of the two marking lines are detected.

wobei P die durchschnittliche Zugfestigkeit ist, F die maximale Bruchkraft ist und A die durchschnittliche anfängliche Querschnittsfläche ist, $$\alpha \left(\text{\%}\right)=\frac{L-L_0}{L_0}\times 100$$

wobei α die Reißdehnung ist, L der Skalenabstand beim Reißen ist, und L₀ ist der ursprüngliche Skalenabstand.The mechanical properties can be calculated as follows: $$\text{P}\left(\text{MPa}\right)=\frac{\text{F}}{\text{A}}$$

where P is the average tensile strength, F is the maximum breaking force, and A is the average initial cross-sectional area, $$\alpha \left(\text{\%}\right)=\frac{L-L_0}{L_0}\times 100$$

where α is the elongation at break, L is the scale distance at break, and L ₀ is the original scale spacing.

Test Example 2

• Testdruck: 0,1Mpa

Measurements of water flow and methylene blue retention rates

• Test pressure: 0.1 MPa

• Zuerst wird die Membranprobe in dem Membraneigenschaftstestgerät angebracht;
• Zweitens wird das entionisierte Wasser in den Membranpool des Membraneigenschaftstestgeräts gefüllt;
• Schließlich wird der Membranpool unter Druck gesetzt, damit das entionisierte Wasser in dem Membranpool durch die Membran hindurchtreten und aus dem Auslassende ausströmen kann, um so den Wasserdurchfluss der Membranprobe zu berechnen.

Test steps:

• First, the membrane sample is mounted in the membrane property tester;
• Second, the deionized water is filled into the membrane pool of the membrane property tester;
• Finally, the membrane pool is pressurized so that the deionized water in the membrane pool can pass through the membrane and flow out of the outlet end so as to calculate the water flow rate of the membrane sample.

wobei B der Wasserdurchfluss der Membranprobe mit der Einheit (L · m^-2 · h^-1) ist, V ist das Gesamtvolumen des Wassers, das aus dem Auslassende des Membraneigenschaftstestgeräts ausströmt, D ist die Fläche der Membranprobe und t ist die gesamte Testzeit.The calculation formula of the river: $$B\left(L\cdot m^{-2}\cdot H^{-1}\right)=\frac{V}{D\cdot t}$$

where B is the water flow of the membrane sample with the unit (L * m ^-2 * h ^-1 ), V is the total volume of water flowing out of the outlet end of the membrane property tester, D is the area of the membrane sample and t is the total test time.

• Testinstrument: Ultrafiltrationsbecher, UV/Vis-Spektrophotometer
• Testdruck: IMpa

Test of retention rate:

• Test instrument: ultrafiltration cup, UV / Vis spectrophotometer
• Test print: IMpa

• Zuerst wird die Membranprobe in dem Ultrafiltrationsbecher angebracht.
• Zweitens wird 1g/l wässrige Methylenblau-Lösung in den Membranpool des Ultrafiltrationsbechers gefüllt.

Test steps:

• First, the membrane sample is placed in the ultrafiltration cup.
• Second, 1 g / L aqueous methylene blue solution is filled into the membrane pool of the ultrafiltration cup.

Third, the membrane pool is pressurized so that the aqueous methylene blue solution in the membrane pool can pass through the membrane, retaining at least a portion of the methylene blue on the membrane, and the remainder of the aqueous methylene blue solution flows out of the outlet end.

Finally, the methylene blue concentrations of the aqueous methylene blue solution in the membrane pool and the methylene blue solution flowing out of the outlet end are detected by the ultraviolet spectrophotometer to calculate the methylene blue retention rate of the membrane sample.

wobei R die Methylenblau-Rückhalterate der Membranprobe bezeichnet, c bezeichnet die Methylenblau-Konzentration der Methylenblau-Lösung, die aus dem Auslassende strömt, und c₀ ist die Methylenblau-Konzentration der Methylenblau-Lösung im Membranpool. Tabelle 2 Beispiel Durchschnittliche Zugfestigkeit (Mpa) (23°C) Reißdehnung (%) Wasserdurchfluss (L·m^-2·MPa^-1·h^-1) Methylenblau-Rückhalterate (%) Beispiel 1 150.9 100 139.2 56 Beispiel2 101.1 60 144.5 19 Beispiel3 129.3 76 100.7 47 Beispiel4 104.1 58 135.5 39 Beispiel5 136.9 90 99.7 49 Beispiel6 149.5 93 94.8 41 Beispiel7 143.2 80 112.4 38 Beispiel8 141.1 93 130.2 52 Beispiel9 132.1 86 128.9 36 Beispiel 10 134.5 87 105.9 62 Referenz 89.7 55 103.6 34 The calculation formula of the retention rate: $$R\left(\text{\%}\right)=\frac{c}{c_0}\times 100$$

where R denotes the methylene blue retention rate of the membrane sample, c denotes the methylene blue concentration of the methylene blue solution flowing out of the outlet end, and c ₀ is the methylene blue concentration of the methylene blue solution in the membrane pool. Table 2 example Average tensile strength (Mpa) (23 ° C) Elongation at break (%) Water flow (L · m ^-2 · MPa ^-1 · h ^-1 ) Methylene blue retention rate (%) example 1 150.9 100 139.2 56 Example 2 101.1 60 144.5 19 Example 3 129.3 76 100.7 47 Example 4 104.1 58 135.5 39 Example 5 136.9 90 99.7 49 Example 6 149.5 93 94.8 41 Example 7 143.2 80 112.4 38 Example 8 141.1 93 130.2 52 Example 9 132.1 86 128.9 36 Example 10 134.5 87 105.9 62 reference 89.7 55 103.6 34

It can be seen from Table 2 that Examples 1-10 have an average tensile strength and elongation at break higher than that of the Reference Example, indicating that the addition of lignin can improve the mechanical properties of the membrane.

In addition, the comparative results obtained by comparing the water flows and the methylene blue retention rates between Examples 1-10 and the Reference Example show that with the addition of an appropriate amount of lignin in the cast membrane solution of the present invention, the retention rate of the ultrafiltration membrane of the present invention is improved is under the condition that the flux is kept constant.

In combination with Tables 1 and 2, the following conclusion is reached:

In Examples 1-3, the mass concentrations of the polyethersulfone are 32%, 20% and 50%, respectively, while the other experimental conditions are the same. It can be seen that the average tensile strength, elongation at break, water flow and methylene blue retention rate in Example 1 are better than those of Examples 2 and 3, indicating that the preferred mass concentration of polyethersulfone is 32%.

In Examples 1, 4 and 5, it can be seen that the average tensile strength, elongation at break, water flux and methylene blue retention rate in Example 1 are better than those of Example 4 and Example 5, indicating that the preferred mass ratio of lignin and polyethersulfone is 0.5: 1.

In Examples 1, 6 and 7, it can be seen that the average tensile strength, elongation at break, water flux and methylene blue retention rate in Example 1 are better than those of Examples 6 and 7, indicating that the preferred mass ratio of PVP and polyethersulfone is 0.05: 1.

Comparing Examples 1 and 8, it can be seen that the average tensile strength, elongation at break, water flux and methylene blue retention rate in Example 1 are better than those of Example 8, indicating that the second temperature, the third temperature , the first humidity and the second humidity are preferably 20 ° C, 20 ° C, 20% and 20%, respectively.

Comparing Examples 1, 9 and 10, it can be seen that the average tensile strength, elongation at break, water flux and methylene blue retention rate in Example 1 are better than those of Examples 9-10, indicating that the first temperature , the first period, the second period and the third period are preferably 65 ° C, 8 h, 15 s and 10 min, respectively.

In summary, Examples 1-10 are preferable to the Reference Example; Example 1, Example 4, Example 7 and Example 8 are more preferred; and Example 1 is most preferred.

Claims (5)

A process for producing an ultrafiltration membrane, comprising the steps of: dissolving polyethersulfone, lignin and polyvinylpyrrolidone in N, N-dimethylacetamide at a first temperature to form a first casting membrane solution, and leaving to defoam at a second temperature and a first moisture over one first period to obtain a treated pourable membrane solution; Pouring the treated cast membrane solution onto a glass substrate and obtaining a membrane in the liquid state having a thickness of 150-250μm using a membrane applicator; Allowing the membrane to volatilize in the liquid state at a third temperature and a second humidity for a second period of time and the glass substrate together with the membrane formed thereon in the liquid state in a coagulation bath, so that solidify the membrane in the liquid state can, so that a solid-state membrane is obtained; and removing the solid-state membrane from the coagulation bath, air-drying and drying it in a drying oven for a third time period to obtain the ultrafiltration membrane. Method according to Claim 1 wherein the first temperature is 50-90 ° C; the second temperature is 15-25 ° C; the third temperature is 15-25 ° C; the first humidity is 10% -30%; the second humidity is 10% -30%; the first period is 6-10 hours; the second period 10-120 seconds; and the third period is 60 minutes. Method according to Claim 1 wherein in the treated cast membrane solution, the mass concentration of polyethersulfone is 20% -40%, the mass ratio of lignin and polyethersulfone is 0.1-1: 1, and the mass ratio between polyvinylpyrrolidone and polyethersulfone is 0.01-0.1: 1. Method according to Claim 1 wherein in the third step the coagulation bath is deionized water. Ultrafiltration membrane manufactured according to one of Claims 1 - 4 ,