KR20190059634A - An ultrafiltration membrane and its preparation method - Google Patents

Abstract

The present invention relates to an ultrafiltration membrane having high mechanical properties and to a preparing method thereof. The preparing method of the present invention comprises the steps of: forming an initial cast membrane solution and standing the same for a first period to remove bubbles so as to obtain a treated cast membrane solution; obtaining a liquid state membrane; obtaining a solid state membrane; and forming an ultrafiltration membrane.

Description

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

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

At present, the ultrafiltration membrane is pressurized for a long time and its mechanical properties are not good, so the life of the ultrafiltration membrane is shortened and it is necessary to frequently replace the ultrafiltration membrane in the membrane module.

Therefore, it is necessary to develop an ultrafiltration membrane having improved mechanical properties. An object of the present invention is to provide an ultrafiltration membrane having excellent mechanical properties and a method for producing the same.

According to one aspect of the present invention, ammonium lignosulfonate is added to the cast film solution.

According to one aspect of the present invention, there is provided a method of manufacturing an ultrafiltration membrane comprising:

The sulfonated polysulfone, ammonium lignosulfonate and aluminum oxide are dissolved in N, N-dimethylacetamide at a first temperature to form an initial cast film solution, and a second temperature and a second temperature to obtain the treated cast film solution. 1 < / RTI > humidity for a first period of time;

Pouring the treated cast film solution onto a glass substrate using a film applicator to obtain a liquid state film having a thickness of 150-250 mu m;

Volatilizing the liquid state film at a third temperature and a second humidity for a second period of time and leaving the glass substrate on which the liquid state film is formed in a coagulation bath to solidify the liquid state film to obtain a solid state film;

Removing the solid state film from the coagulation bath, air drying and drying in an oven for a third period of time to form an ultrafiltration membrane.

In one embodiment, 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% 2 humidity is 10-30%, the first period is 6-10 hours, the second period is 10-120 seconds, and the third period is 60 minutes.

In one embodiment, in the treated cast film solution, the mass concentration of the sulfonated polysulfone is 20-40%, the mass ratio between the ammonium lignosulfonate and the sulfonated polysulfone is 0.1-1: 1 , And the mass ratio between the aluminum oxide and the sulfonated polysulfone is 0.01-0.1: 1.

In one embodiment, the coagulation bath uses deionized water.

According to an aspect of the present invention, there is provided an ultrafiltration membrane according to the above method.

According to the present invention, ammonium lignosulfonate is added to the cast film solution to improve the reaction rate of the ultrafiltration membrane.

Example 1

Step 1: 16 g of sulfonated polysulfone, 8 g of ammonium lignosulfonate and 0.8 g of ammonium oxide were added to a three-necked flask;

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

Step 3: In order to remove the bubbles, leave the bubbles at 20 ° C and 20% humidity for 8 hours to obtain a foam-free casting membrane solution;

Step 4: The cast film solution was poured onto a glass substrate by a film applicator and a liquid film of 200 mu m thickness was obtained;

Step 5: A glass substrate with a liquid state film was allowed to volatilize for 15 seconds in an atmosphere at 20 占 폚 and 20% relative humidity;

Step 6: A glass substrate having a liquid state film was placed in deionized water to solidify the liquid state film into a solid state film;

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

For the control experiment, a control membrane was obtained under the same conditions as in Example 1, except that ammonium lignosulfonate was not added.

Item  Example 1 Example 2 Example 3 Example 4 Example 5 Example 6 Example 7 Example 8 Example 9 Example 10 Control Example Mass concentration (%) of sulfonated polysulfone 32 20 50 32 32 32 32 32 32 32 The mass ratio of ammonium lignosulfonate to sulfonated polysulfone 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 ammonium oxide to sulfonated polysulfone 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 (占 폚) 65 65 65 65 65 65 65 65 50 90 65 The second temperature (캜) 20 20 20 20 20 20 20 15 20 20 20 Third temperature (캜) 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 Second humidity (%) 20 20 20 20 20 20 20 30 20 20 20 In the first period (time) 8 8 8 8 8 8 8 8 10 6 8 Second period (seconds) 15 15 15 15 15 15 15 15 10 120 13 The third period (minutes) 10 10 10 10 10 10 10 10 5 60 10

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

All other experimental conditions were the same except that the mass ratios between ammonium lignosulfonate and sulfonated polysulfone were 0.5: 1, 0.1: 1 and 1: 1, respectively, in Examples 1, 4 and 5.

In Examples 1, 6 and 7, all other experimental conditions were the same except that the mass ratio between ammonium oxide and sulfonated polysulfone was 0.05: 1, 0.01: 1 and 0.1: 1, respectively.

In Examples 1 and 8, all other experimental conditions were the same except that in Example 1, the second and third temperatures, the first humidity and the second humidity were 20 < 0 > C and 20 & % In Example 8, but 15% and 25%, 10% and 30% in Example 8, respectively. That is, the atmosphere for the solid state film and the defoaming condition were different.

In Examples 1, 9 and 10, all other conditions were the same except that the first temperature, the first period, the second period and the third period were different. That is, the temperature for producing the cast film solution, the period for preparing the cast film solution, the period for volatilization of the applied liquid horse, and the period for drying the film sample were different.

Test Example 1

The mechanical properties of the membranes prepared in Examples 1-10 of Table 1 and the mechanical properties of the control examples were measured and compared and the results are summarized in Table 2 below.

Mechanical properties test:

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

Testing phase:

First, the film sample to be tested was cut into a shape suitable for the tester and the scale distance was marked with two mark lines;

The cut film sample was then carefully placed in a holder of the tester and carefully adjusted to a symmetrical position such that the stretching force was evenly distributed on the cross section of the film sample;

Finally, the tester was actuated and the maximum force (± 1% error) at which the film sample was ruptured and the distance between the inside of the two mark lines (± 1.25 mm error) were recorded.

The mechanical properties can be calculated as follows:

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

α (%) = {(LL 0) / L 0}} x 100 ( Equation 2), where α is an elongation (elongation), L is the distance from the scale burst in burst, L ₀ is the initial distance scale.

Test Example 2

Measurement of water flux and methylene blue retention

Test pressure: 0.1Mpa

Testing phase:

First, a film sample is mounted on a film property tester;

Next, the deionized water is filled into the membrane pool of the membrane property tester;

Finally, to calculate the flow rate of the membrane sample, the membrane was pressurized so that deionized water in the membrane pool passed through the membrane and exited the outlet.

Calculation of runoff formula:

^{B (L · m -2 · h} -1) = V / (D · t) ( Equation 3), where B is a unit of water flow of the film sample is L · m ^-2 · h ^- is ^1, V is film D is the area of the membrane sample, and t is the bar test time.

Retention rate test:

Test instrument: ultrafiltration cup, UV spectrometer

Test pressure: 1Mpa

Testing phase:

First, the membrane sample was mounted in an ultrafiltration cup;

Next, a 1 g / L methylene blue aqueous solution was charged into the membrane pool of the ultrafiltration cup;

Next, the membrane pool was pressurized so that the aqueous solution of methylene blue in the membrane pool passed through the membrane, where at least a portion of the methylene blue was retained on the membrane and the remainder of the aqueous methylene blue solution exited the outlet end;

Finally, for the calculation of the methylene blue retentivity of the membrane sample, the concentration of methylene blue in the methylene blue aqueous solution and the concentration of the methylene blue aqueous solution exiting to the outlet end in the membrane pool were detected using a UV spectrometer.

Calculation of retention rate Formula:

R (%) = a _{(c / c 0) x 100} ( Equation 4), wherein, R is methylene blue retention rate of the film sample, c is the concentration of methylene blue of the methylene blue aqueous solution exiting the outlet end, c ₀ Is the concentration of methylene blue in the methylene blue aqueous solution in the membrane pool.

Yes Average tensile force (Mpa) (23 DEG C) Elongation at break (%) Flow rate (Lm ^-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 Control Example 89.7 55 103.6 34

In Table 2, Example 1-10 shows higher elongation and average tensile strength at break than the control example, which means that the addition of ammonium lignosulfonate improves the mechanical properties of the film.

In addition, the results obtained by comparing the flow rates between Examples 1-10 and the control and the methylene blue retentivity are as follows: The addition of an appropriate amount of ammonium lignosulfonate to the casting membrane solution allows the retention ratio of the ultrafiltration membrane to be maintained at a constant flow rate Lt; / RTI >

Taking Tables 1 and 2 into consideration, the following conclusions can be drawn:

In Examples 1-3, the mass concentrations of the sulfonated polysulfone were 32%, 20% and 50%, respectively, and the remaining experimental conditions were the same. Example 1 shows that the elongation at break, the average tensile force, the flow rate and the methylene blue retention are better than those of Examples 2 and 3, indicating that the mass concentration of the sulfonated polysulfone is preferably 32%.

In Examples 1, 4, and 5, Example 1 had better burst elongation, average tensile strength, flow rate, and methylene blue retention than Examples 4 and 5, with a mass ratio of ammonium lignosulfonate to sulfonated polysulfone of 0.5: 1 < / RTI >

In Examples 1, 6 and 7, Example 1 exhibited better elongation at break, average tensile force, flow rate and methylene blue retention than Examples 6 and 7, which desirably had a mass ratio of aluminum oxide to sulfonated polysulfone of 0.05: 1 Respectively.

Comparing Example 1 and Example 8, Example 1 showed that the elongation at break, the average tensile force, the flow rate, and the methylene blue retention were better than Example 8, indicating that the second temperature, the third temperature, the first humidity, , 20 ° C, 20% and 20%, respectively.

Comparison of Examples 1, 9 and 10 shows that Example 1 had better rupture elongation, average tensile strength, flow rate and methylene blue retention than Examples 9 and 10, Lt; RTI ID = 0.0 > 65 C, < / RTI > 8 hours, 15 seconds and 10 minutes, respectively.

Consequently, as compared with the control example, Example 1-10 is preferable, and Examples 1, 4, 7, and 8 are more preferable, and Example 1 is most preferable.

Claims (5)

A method of making an ultrafiltration membrane comprising:
The sulfonated polysulfone, ammonium lignosulfonate and aluminum oxide are dissolved in N, N-dimethylacetamide at a first temperature to form an initial cast film solution, and a second temperature and a second temperature to obtain the treated cast film solution. 1 < / RTI > humidity for a first period of time;
Pouring the treated cast film solution onto a glass substrate using a film applicator to obtain a liquid state film having a thickness of 150-250 mu m;
Volatilizing the liquid state film at a third temperature and a second humidity for a second period of time and leaving the glass substrate on which the liquid state film is formed in a coagulation bath to solidify the liquid state film to obtain a solid state film;
Removing the solid state film from the coagulation bath, air drying, and drying in an oven for a third period of time to form an ultrafiltration membrane. The method according to claim 1,
The first temperature is 50-90 < 0 > C,
The second temperature is 15-25 < 0 > 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 is 10-120 seconds,
And the third period is 60 minutes. The method according to claim 1,
In the treated cast film solution, the mass concentration of the sulfonated polysulfone is 20-40%
The mass ratio of the ammonium lignosulfonate to the sulfonated polysulfone is 0.1-1: 1,
Wherein the mass ratio of said aluminum oxide to said sulfonated polysulfone is 0.01-0.1: 1. The method according to claim 1,
Wherein said coagulating bath uses deionized water. An ultrafiltration membrane produced by the method of any one of claims 1 to 4.