KR20190083732A - An Ultrafiltration Membrane and its Preparation Method - Google Patents

Abstract

The present invention relates to a method for manufacturing an ultrafiltration membrane having excellent mechanical properties. In the present invention, hemicellulose having excellent mechanical properties is added to a casting membrane solution, so that the retention rate of the ultrafiltration membrane is enhanced. The method comprises a step of obtaining a cast membrane solution by dissolving polyvinyl alcohol, hemicellulose, and titanium dioxide in N,N-dimethylacetamide.

Description

BACKGROUND OF THE INVENTION 1. Field of the Invention [0001] The present invention relates to an ultrafiltration membrane,

The present invention relates to an ultrafiltration membrane having high mechanical properties and a method for producing the same.

Currently, ultrafiltration membranes are pressurized for a long time, but their mechanical properties are poor, shortening the life of ultrafiltration membranes and requiring frequent replacement of ultrafiltration membranes in membrane modules.

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

It is an object of the present invention to provide an ultrafiltration membrane having high mechanical properties and a method for producing the same.

The present invention relates to a method for producing an ultrafiltration membrane having high mechanical properties. In the present invention, hemicellulose having high mechanical properties is added to a casting membrane solution to improve the retention rate of the ultrafiltration membrane of the present invention.

Example 1

Step 1: 16 g of polyvinyl alcohol, 8 g of hemicellulose and 0.8 g of titanium dioxide were added to a three-necked flask;

Step 2: 50 g of N, N-dimethylacetamide was then added to the three-necked flask to obtain a mixture and the mixture was stirred at 65 DEG C for 5 hours;

Step 3: Leave to bubble for 8 hours at a temperature of 20 ° C and a humidity of 20% to obtain a uniform, bubble-free casting membrane solution;

Step 4: The casting membrane solution was poured onto a glass substrate, and the casting membrane solution on the glass substrate was coated with a membrane applicator to obtain a liquid membrane having a thickness of 200 m;

Step 5: The glass substrate on which the liquid membrane was formed was volatilized for 15 seconds at a temperature of 20 캜 and a humidity environment of 20%;

Step 6: The glass substrate on which the liquid membrane was formed was put into deionized water to solidify the liquid membrane into a solid phase membrane;

Step 7: The solid membrane was taken out of deionized water, air dried, and then placed in a drying oven for 10 minutes to obtain an ultrafiltration membrane.

In the comparative example, the experimental conditions were the same as those in Example 1, except that hemicellulose was not added.

division Example 1 Example 2 Example 3 Example 4 Example 5 Example 6 Example 7 Example 8 Example 9 Example 10 Comparative Example Mass concentration (%) of polyvinyl alcohol 32 20 50 32 32 32 32 32 32 32 32 The mass ratio of hemicellulose to polyvinyl alcohol 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 - Mass ratio of titanium dioxide to polyvinyl alcohol 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 Primary temperature (℃) 65 65 65 65 65 65 65 65 50 90 65 Secondary temperature (캜) 20 20 20 20 20 20 20 15 20 20 20 Tertiary temperature (캜) 20 20 20 20 20 20 20 25 20 20 20 Primary humidity (%) 20 20 20 20 20 20 20 10 20 20 20 Secondary humidity (%) 20 20 20 20 20 20 20 30 20 20 20 The first period (h) 8 8 8 8 8 8 8 8 10 6 8 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 to 3, the experimental conditions were all the same except that the mass concentrations of polyvinyl alcohol were 32%, 20%, and 50%, respectively.

In Examples 1, 4 and 5, the experimental conditions were all the same except that the mass ratio between hemicellulose and polyvinyl alcohol was 0.5: 1, 0.1: 1 and 1: 1, respectively.

In Examples 1, 6, and 7, the experimental conditions were all the same except that the mass ratio between titanium dioxide and polyvinyl alcohol was 0.05: 1, 0.01: 1, and 0.1: 1, respectively.

In Examples 1 and 8, the secondary and tertiary temperatures, primary and secondary humidity were 20 ° C, 20 ° C, 20%, and 20%, respectively in Example 1, 10% and 30%, respectively. That is, the environment in which the foam was removed and the solid membrane was formed was different.

In Examples 1, 9 and 10, the primary temperature, the primary, secondary and tertiary periods, that is, the temperature at which the casting membrane solution is prepared, the period during which the casting membrane solution is prepared, the period during which the applied liquid membrane is volatilized, The experimental conditions were all the same except that the period of drying the membrane samples was different.

room Stunning  One

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

Mechanical properties test:

Test apparatus: Paper and paper board tensile tester ZL-100A

Testing phase:

First, the membrane sample to be tested is cut to the shape of the tester and the scale distance is indicated by two markers;

Second, the cut membrane sample was placed in a holder of the tester and carefully adjusted to a symmetrical position so that a stretching force was evenly distributed over the cross-section of the membrane sample;

Finally, the tester was run and the maximum force (error ± 1%) at which the membrane sample was broken and the distance between the inside of the two marks (error ± 1.25 mm) were recorded.

The mechanical properties can be calculated as follows:

Where P is the average tensile strength, F is the maximum force at break, and A is the average initial cross-sectional area.

In the above equation ,? Is the elongation at break, L is the scale distance at break, and L ₀ is the initial scale distance.

Experimental Example  2

Determination of oil content and methylene blue retention

Test pressure: 0.1 MPa

Testing phase:

First, the membrane sample was placed on a membrane characterization tester;

Second, deionized water was charged to the membrane pool of the membrane characterization tester;

Finally, to calculate the flow rate of the membrane sample, pressure was applied to the membrane pool so that deionized water from the membrane pool flowed out of the outlet end through the membrane.

Calculation of flow rate:

Wherein, B is ^{- (L · m -2 · h 1} ) water flow of the membrane samples of the unit, V is the total volume of water flowed out of the outlet end of the membrane characteristics tester, D is the area of the membrane sample, t is Total test time.

Retention rate test:

Test apparatus: ultrafiltration cup, ultraviolet and visible light spectrophotometer

Test pressure: 1 Mpa

Testing phase:

First, the membrane sample was placed in an ultrafiltration cup.

Second, a 1 g / L aqueous methylene blue solution was charged to the membrane pool of the ultrafiltration cup.

Third, pressure was applied to the membrane pool to allow a methylene blue aqueous solution of the membrane pool to pass through the membrane, leaving at least a portion of the methylene blue on the membrane, leaving the remainder of the aqueous methylene blue solution out of the outlet end.

Finally, the methylene blue aqueous solution in the membrane pool and the methylene blue concentration of the methylene blue aqueous solution flowing out of the outlet end were measured with an ultraviolet spectrophotometer, and the methylene blue retention ratio of the membrane sample was calculated.

Retention rate calculation formula:

Where R is the methylene blue retention of the membrane sample, c is the methylene blue concentration of the methylene blue aqueous solution flowing out of the outlet end and c ₀ is the methylene blue concentration of the methylene blue aqueous solution in the membrane pool.

Average tensile strength
(Mpa) (23 < 0 > C) Elongation at break (%) water flow
^{(L · m -2 · MPa -1} · h -1) Methylene Blue Retention (%) 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 Comparative Example 89.7 55 103.6 34

It can be seen from Table 2 that Examples 1 to 10 have higher average tensile strength and elongation at break than the Comparative Examples, indicating that the addition of hemicellulose can improve the mechanical properties of the membrane.

The comparison results obtained by comparing the water content between Examples 1 to 10 and the comparative example with the methylene blue retentivity indicate that by adding an appropriate amount of hemicellulose to the casting membrane solution according to the present invention, Indicating that the retention ratio of the ultrafiltration membrane is improved.

Combining Tables 1 and 2, we arrive at the following conclusions:

In Examples 1 to 3, the mass concentrations of polyvinyl alcohol are 32%, 20%, and 50%, respectively, and the other experimental conditions are the same. It can be seen that Example 1 has better average tensile strength, elongation at break, water content and methylene blue retention than Examples 2 and 3, indicating that the preferred mass concentration of polyvinyl alcohol is 32%.

In Examples 1, 4, and 5, it can be seen that Example 1 is superior to Examples 4 and 5 in terms of average tensile strength, elongation at break, water retention, and methylene blue retention ratio, which is the ratio of the weight ratio of hemicellulose and polyvinyl alcohol Is 0.5: 1.

In Examples 1, 6 and 7, it can be seen that Example 1 is superior to Examples 6 and 7 in terms of average tensile strength, elongation at break, water retention and methylene blue retention, which is a desirable mass of titanium dioxide and polyvinyl alcohol Indicating that the ratio is 0.05: 1.

Comparing Examples 1 and 8, it can be seen that Example 1 is superior to Example 8 in terms of average tensile strength, elongation at break, oil content and methylene blue retention, And secondary humidity of 20 [deg.] C, 20 [deg.] C, 20% and 20%, respectively.

Comparing Examples 1, 9 and 10, it can be seen that Example 1 is superior to Examples 9 and 10 in terms of average tensile strength, elongation at break, flow rate and methylene blue retention, , And the secondary and tertiary periods are preferably 65 ° C, 8 hours, 15 seconds and 10 minutes, respectively.

Consequently, in comparison with the comparative examples, Examples 1 to 10 are preferable, and Examples 1, 4, 7 and 8 are more preferable, and Embodiment 1 is most preferable.

Claims (5)

Polyvinyl alcohol, hemicellulose and titanium dioxide are dissolved in N, N-dimethylacetamide at a first temperature to form an initial casting membrane solution and bubbles are removed during the first period at a second temperature and primary humidity, Obtaining a casting membrane solution;
Pouring the treated casting membrane solution onto a glass substrate and obtaining a liquid membrane having a thickness of 150 to 250 mu m using a membrane applicator;
Volatilizing the liquid membrane at a third temperature and a second humidity for a second period of time and solidifying the liquid membrane by placing the glass substrate on which the liquid membrane is formed in a coagulation bath to obtain a solid phase membrane;
Removing the solid membrane from the coagulating bath, air drying, and drying in a drying oven for a third period of time to obtain an ultrafiltration membrane. The process of claim 1, wherein the primary temperature is from 50 to 90 占 폚;
The secondary temperature is 15 to 25 占 폚;
The tertiary temperature is 15 to 25 占 폚;
The primary humidity is 10 to 30%;
The secondary humidity is 10 to 30%;
The primary period is 6 to 10 hours;
The second period is 10 to 120 seconds;
And the third period is 60 minutes. The method of claim 1, wherein in the treated casting membrane solution,
The mass concentration of the polyvinyl alcohol is 20 to 40%
The mass ratio of hemicellulose to polyvinyl alcohol is 0.1 to 1: 1,
Wherein the mass ratio of titanium dioxide to polyvinyl alcohol is 0.01 to 0.1: 1. The method of claim 1, wherein, in the third step, the coagulation bath is deionized water. 5. An ultrafiltration membrane produced by the process of any one of claims 1 to 4.