KR20190093888A - An ultra-filtration membrane and its preparation method - Google Patents

Abstract

The present invention relates to a method for manufacturing an ultrafiltration membrane with good mechanical properties. In the present invention, alkali lignin having good mechanical properties is added to a casting membrane solution, so that the retention rate of the ultrafiltration membrane can be enhanced.

Description

Ultrafiltration membrane and manufacturing method thereof {AN ULTRA-FILTRATION MEMBRANE AND ITS PREPARATION METHOD}

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

Due to the fact that the ultrafiltration membrane has been pressurized for a long time and has poor mechanical properties, the ultrafiltration membrane currently has a short operating time, and the ultrafiltration membrane mounted in the membrane module needs to be frequently replaced.

Therefore, there is a need to develop a method for producing an ultrafiltration membrane capable of improving the mechanical properties of the ultrafiltration membrane.

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

In order to achieve the above object, the present invention relates to a method for producing an ultrafiltration membrane having a number of mechanical properties.

In the ultrafiltration membrane production method according to embodiments of the present invention, polycarbonate, alkaline lignin and N-butyl alcohol in N-dimethylacetamide at a first temperature Is dissolved to form an initial casting membrane solution and antifoamed at a second temperature and a second humidity for a first time to obtain a treated casting membrane solution. The treated casting membrane solution is poured onto a glass substrate and a liquid membrane having a thickness of 150 to 250 μm is obtained using a membrane applicator. The liquid membrane is solidified by solidifying the liquid membrane by volatilizing the liquid membrane at a third temperature and a second humidity for a second time and placing the glass substrate together with the liquid membrane formed thereon in a coagulation bath. Acquire. The ultrafiltration membrane is then obtained by extracting the solid membrane from the coagulation bath and drying in a drying oven for a third time.

In one embodiment of the present invention, the first temperature is 50 to 90 ° C, the second temperature is 15 to 25 ° C, the third temperature is 15 to 25 ° C, the first humidity is 10 to 30%, the second humidity is 10 to 30%, the first time is 6 to 10 hours, the second time is 10 to 120 seconds, the third time may be 60 minutes.

In one embodiment of the present invention, the treated casing membrane solution has a polycarbonate of 20 to 40% by weight, the mass ratio of the alkali lignin to the polycarbonate is 0.1 to 1: 1, compared to the polycarbonate The mass ratio of the N-butyl alcohol may be 0.01 to 0.1: 1.

In one embodiment of the present invention, the coagulation bath may include deionized water.

In the present invention, by adding alkali lignin having excellent mechanical properties into the casting membrane solution, the retention rate of the ultrafiltration membrane can be improved.

Hereinafter, embodiments of the present invention will be described in detail. As the inventive concept allows for various changes and numerous modifications, particular embodiments will be illustrated and described in detail in the text. However, this is not intended to limit the present invention to the specific disclosed form, it should be understood to include all modifications, equivalents, and substitutes included in the spirit and scope of the present invention. The size and amount of the objects are shown to be enlarged or reduced than actual for clarity of the invention.

Terms such as first and second may be used to describe various components, but the components should not be limited by the terms. The terms are used only for the purpose of distinguishing one component from another. For example, without departing from the scope of the present invention, the first component may be referred to as the second component, and similarly, the second component may also be referred to as the first component.

The terminology used herein is for the purpose of describing particular example embodiments only and is not intended to be limiting of the present invention. Singular expressions include plural expressions unless the context clearly indicates otherwise. In this application, the terms "comprise" or "include" are intended to indicate that there is a feature, step, function, component, or combination thereof described on the specification, and other features, steps, functions, components Or it does not exclude in advance the possibility of the presence or addition of them in combination.

On the other hand, unless otherwise defined, all terms used herein, including technical or scientific terms, have the same meaning as commonly understood by one of ordinary skill in the art. Terms such as those defined in the commonly used dictionaries should be construed as having meanings consistent with the meanings in the context of the related art and shall not be construed in ideal or excessively formal meanings unless expressly defined in this application. Do not.

As mentioned above, although the Example of this invention was described in detail, these are only illustrations and do not limit a claim. The technology described in the claims includes various modifications or variations of the specific examples described above. In addition, the technical elements described in this specification or the drawings exhibit technical usefulness alone or in various combinations, and are not limited to the combinations described in the claims at the time of filing. In addition, the technique illustrated in the present specification or the drawings is to achieve a plurality of objects at the same time, and has the technical usefulness by achieving one of them.

Example 1

First step; 16 g polycarbonate, 8 g alkaline lignin and 0.8 g N-butyl alcohol are added into a three neck flask.

Second step; 50 g of N-dimethylacetamide are then added into a three neck flask to obtain a mixture. The mixture was stirred at 65 ° C. for 5 hours.

Third step; Defoaming at 20 ° C. and 20% humidity atmosphere yields a constant pore-free caching membrane solution.

A fourth step; The casting membrane solution is poured onto a glass substrate and the casting membrane solution on the organic substrate is applied to a membrane applicator to obtain a liquid membrane having a thickness of 200 μm.

A fifth step; The glass substrate with the liquid membrane formed thereon is placed for 15 seconds for volatilization in an atmosphere of 20 ° C. temperature and 20% humidity.

Sixth step; A glass substrate with a liquid membrane formed thereon is placed in deionized water to solidify the liquid membrane into a solid membrane.

Seventh step; The solid membrane is withdrawn from deionized water and placed in an air drying and drying oven for 10 minutes to obtain the ultrafiltration membrane.

As a comparative example, all the other process conditions are the same as in Example 1 except that only alkali lignin is 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% of polycarbone 32 20 50 32 32 32 32 32 32 32 32 Mass ratio of alkali lignin to polycarbonate 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 N-butyl alcohol to polycarbonate 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 First temperature
(℃) 65 65 65 65 65 65 65 65 50 90 65 Second temperature
(℃) 20 20 20 20 20 20 20 15 20 20 20 Third temperature
(℃) 20 20 20 20 20 20 20 25 20 20 20 1st humidity (%) 20 20 20 20 20 20 20 10 20 20 20 2nd humidity (%) 20 20 20 20 20 20 20 30 20 20 20 First hour (h) 8 8 8 8 8 8 8 8 10 6 8 Second time (s) 15 15 15 15 15 15 15 15 10 120 15 3rd time
(min.) 10 10 10 10 10 10 10 10 5 60 10

In Examples 1 to 3, all are the same, except that the mass% of the polycarbonate is 32%, 20% and 50%, respectively.

In Examples 1, 4 and 5, all were the same except that the mass ratio of alkali lignin to polycarbonate was 0.5: 1. 0.1: 1 and 0.1: 1, respectively.

In Examples 1, 6 and 7, all were the same except that the mass ratio of N-butyl alcohol to polycarbonate was 0.05: 1. 0.01: 1 and 0.1: 1, respectively.

In Examples 1 and 8, all other process conditions are the same as in Example 1 except that in Example 1, the second temperature, the third temperature, the first humidity and the second humidity are 20 ° C., 20 °. C, 20% and 20%, and for Example 8, the second temperature, third temperature, first humidity and second humidity are 15 ° C, 25 ° C, 10% and 30%. That is, the atmospheres of a defoaming process and a solid membrane shape process are mutually different.

In Examples 1, 9 and 10, all other process conditions are the same except that the first temperature, the first time, the second time and the third time are different from each other. That is, the temperature for forming the casting membrane solution, the time for forming the casting membrane, the time for volatilizing the applied liquid membrane and the time for drying the membrane sample are different.

Test 1

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

Mechanical property test:

Test Equipment: Paper & Paper Board Tensile Tester ZL-100A

Test procedures;

First, the membrane sample to be tested is cut into a shape that can be mounted to the tester, and the scale distance is marked with two marking lines.

Second, the cut membrane sample is mounted in a holder of the tester and adjusted to a symmetrical position so that the tensile force can be uniformly distributed along the intersection line of the membrane sample.

Finally, the tester is operated and the maximum force at which the membrane sample is broken (1% error) and the distance between the inner sides of the two marking lines (1.25 mm error) are recorded.

Mechanical properties are calculated by the following equation (1).

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

Where α represents elongation at break, L represents scale distance at break, and L ₀ represents initial scale distance.

Test 2

Water flow rate and retention of methylene blue

Test pressure: 0.1 MPa

Test procedures;

First, the membrane sample is mounted to a membrane characteristic tester.

Second, deionized water is filled into the membrane pool of the membrane property tester.

Finally, the membrane pool is pressurized and passed through the deionized water membrane in the membrane pool to the outlet, thereby calculating the water flow rate of the membrane sample.

The calculation formula of the flow velocity is shown in Equation 3 below.

B corresponds to the water flow rate of the membrane sample with units of Lm ⁻² ㅇ h ⁻¹ , V is the total volume of water flowing out of the discharge end of the membrane characteristic tester, D is the area of the membrane sample, and t is Corresponds to the total test time.

Retention rate measurement;

Test equipment: ultrafiltration cups, ultra-violet-visible spectrophotometer

Testing pressure: 1 Mpa

Test procedures;

First, the membrane sample is mounted in an ultrafiltration cup.

Second, 1 g / L methylene blue aqueous solution is injected into the membrane pool of the ultrafiltration cup.

Third, the methylene blue concentration of the methylene blue aqueous solution in the membrane pool and the methylene blue aqueous solution discharged from the discharge end is measured by an ultraviolet-visible spectrophotometer to calculate the methylene blue retention of the membrane sample.

The formula for calculating the retention rate is shown in Equation 4 below.

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

sample Average Tensile Strength (Mpa) (23 ℃) Elongation at Break (%) Water flow rate
(L ㅇ m ^-2 ㅇ MPa ^-1 ㅇ 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 Comparative example 89.7 55 103.6 34

As can be seen in Table 2, Examples 1 to 10 have greater average tensile strength and elongation at break than Comparative Examples, indicating that the addition of alkali lignin can improve the mechanical properties of the membrane.

In addition, the comparison results obtained by comparing the water flux and the methylene blue retention between the Examples 1 to 10 and the Comparative Examples show the following: When an appropriate amount of alkali lignin is added to the casting membrane solution of the present invention, the ultrafine present invention The retention of the filtration membrane is improved under conditions where the flux remains constant.

The following conclusions are drawn from Tables 1 and 2.

In Examples 1-3, the weight percent of polycarbonate is 32%, 20% and 50%, respectively, and the other experimental conditions are the same. Example 1 shows better average weight strength, elongation at break, water flow rate and methylene blue retention than those of Examples 2 and 3, so that the preferred weight percent of polycarbonate is 32%.

In Examples 1, 4 and 5, it can be seen that Example 1 has better average tensile strength, elongation at break, water flow rate and methylene blue retention than Examples 4 and 5, and alkali lignin relative to preferred polycarbonates. The mass ratio is 0.5: 1.

In Examples 1, 6 and 7, it can be seen that Example 1 has better average tensile strength, elongation at break, water flow rate and methylene blue retention than Examples 6 and 7, with N-butyl alcohol over preferred polycarbonates. The mass ratio of is 0.05: 1.

Comparing Examples 1 and 8, Example 1 has better average tensile strength, elongation at break, water flow rate, and methylene blue retention than Example 8, which preferably has a second temperature, a third temperature, a first humidity and The second humidity corresponds to 20 ° C., 20 ° C., 20% and 20%, respectively.

Comparing Examples 1, 9 and 10, Example 1 has better average tensile strength, elongation at break, water flow rate and methylene blue retention than Examples 9-10, which preferably comprises the first temperature, the first time, Corresponds to the case where the second and third times are 65 ° C., 8 hours, 15 seconds and 10 minutes, respectively.

In conclusion, when compared with the comparative example, Examples 1-10 are preferable, Example 1, Example 4, Example 7, and Example 8 are more preferable, and Example 1 is the most preferable.

Claims (5)

Dissolve polycarbonate, alkali lignin and N-butyl alcohol in N-N-dimethylacetamide at a first temperature to form an initial casting membrane solution and at first time, second temperature and A first step of obtaining a treated casting membrane solution by defoaming at a second humidity;
Pouring the treated casting membrane solution onto a glass substrate and obtaining a liquid membrane having a thickness of 150 to 250 μm using a membrane applicator;
The liquid membrane is solidified by volatilizing the liquid membrane at a second time, third temperature and second humidity and placing the glass substrate together with the liquid membrane formed thereon in a coagulation bath. Obtaining a third step; And
And extracting the solid membrane from the coagulation bath and drying in a drying oven for a third time, thereby obtaining a ultrafiltration membrane. The method of claim 1,
The first temperature is 50 to 90 ° C.,
The second temperature is 15 to 25 ° C,
The third temperature is 15 to 25 ° C,
The first humidity is 10 to 30%,
The second humidity is 10 to 30%,
The first time is 6 to 10 hours,
The second time is 10 to 120 seconds,
The third time being 60 minutes
Method for producing a ultrafiltration membrane, characterized in that. The method of claim 1, wherein the treated casing membrane solution,
20 to 40% by weight of polycarbonate,
The mass ratio of the alkali lignin to the polycarbonate is 0.1 to 1: 1,
The mass ratio of the N-butyl alcohol to the polycarbonate is 0.01 to 0.1: 1
Method for producing a ultrafiltration membrane, characterized in that. The method of claim 1, wherein in the third step, the coagulation bath comprises deionized water. Ultrafiltration membrane prepared by the method of any one of claims 1 to 4.