A method for improving membrane flux by using micro-stirring

A membrane flux, micro-stirring technology, applied in chemical instruments and methods, membrane technology, semi-permeable membrane separation, etc., can solve problems such as no prospect of industrial application, inability to adapt to large-scale industrial equipment, complex preparation process, etc. To achieve the effect of a wide range of options, a wide range of applications, flexible and simple operation

Active Publication Date: 2022-07-26
NANJING TECH UNIV
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

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Problems solved by technology

For example, CN201810245865.2 discloses a self-supporting homogeneous forward osmosis membrane that can eliminate internal concentration polarization and its preparation method and application, but the method of changing the performance of the membrane material to achieve the elimination of concentration polarization requires technical preparation Complexity, high R&D cost, and cannot fundamentally solve the phenomenon of water flux reduction caused by concentration polarization in application
In addition, there is also a way to increase the turbulence effect on the outside to slow down the concentration polarization phenomenon. For example, CN201921066192.0 discloses a forward osmosis membrane module that slows down the external concentration polarization and membrane fouling, the raw material liquid side corridor and the draw liquid side corridor There are impellers installed in the road, but this method cannot be adapted to large-scale industrial equipment, and does not have the prospect of industrial application
Moreover, it cannot be stirred between the narrow membrane gaps, which will be hindered in practical applications.

Method used

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  • A method for improving membrane flux by using micro-stirring
  • A method for improving membrane flux by using micro-stirring
  • A method for improving membrane flux by using micro-stirring

Examples

Experimental program
Comparison scheme
Effect test

Embodiment 1

[0038] The specific process of membrane filtration is as follows:

[0039] (1) Add 1 mL of a magnetic stir bar with a diameter of 140 nm to the surface of the nanofiltration membrane in the ultrafiltration cup

[0040] (2) Add 20mL of 5000ppm Na 2 SO 4 For the solution, use a nitrogen bottle to apply a pressure of 0.6 MPa, place a magnetic stirring table under the ultrafiltration cup, rotate at 800 rpm, adopt forward and reverse rotation, and the switching frequency is 1 min.

[0041] (3) The filtered liquid is weighed by an electronic scale, and the sensor on the electronic scale is connected to the flow detection software on the computer to monitor the change of water flux.

[0042] The specific device can be seen figure 1 : (1) nitrogen cylinder, (2) liquid tank, (3) ultrafiltration cup, (4) diaphragm, (5) magnetic stirrer, (6) electronic balance, (7) valve, (8) in the membrane Surface-rotating nano- or micro-scale stir bars

[0043] The preparation process of the magn...

Embodiment 2

[0048] The specific process of membrane filtration is as follows:

[0049] (1) Add 1 mL of a magnetic stir bar with a diameter of 500 nm to the surface of the nanofiltration membrane in the ultrafiltration cup

[0050] (2) Add 20mL of 5000ppm Na 2 SO 4 For the solution, use a nitrogen bottle to apply a pressure of 0.6 MPa, place a magnetic stirring table under the ultrafiltration cup, rotate at 800 rpm, adopt forward and reverse rotation, and the switching frequency is 1 min.

[0051] (3) The filtered liquid is weighed by an electronic scale, and the sensor on the electronic scale is connected to the flow detection software on the computer to monitor the change of water flux.

[0052] The preparation process of the nano-stirring bar is as follows: add 1 mL of the nano-stirring bar obtained in Example 1, 1 mL of isopropanol, 30 μL of ammonia water, and 10 μL of TEOS into a 4 mL sample bottle, and perform the process of coating while inducing again. After the reaction, centri...

Embodiment 3

[0054] The specific process of membrane filtration is as follows:

[0055] (1) Add 1 mL of a magnetic stir bar with a diameter of 1 μm to the surface of the nanofiltration membrane in the ultrafiltration cup.

[0056] (2) Add 20mL of 5000ppm Na 2 SO 4 For the solution, use a nitrogen bottle to apply a pressure of 0.6 MPa, place a magnetic stirring table under the ultrafiltration cup, rotate at 800 rpm, adopt forward and reverse rotation, and the switching frequency is 1 min.

[0057] (3) The filtered liquid is weighed by an electronic scale, and the sensor on the electronic scale is connected to the flow detection software on the computer to monitor the change of water flux.

[0058] The preparation process of the nano-stirring bar: 1 mL of the nano-stirring bar obtained in Example 1, 1 mL of isopropanol, 30 μL of ammonia water, and 10 μL of LTEOS were added to a 4 mL sample bottle, and the process of coating while inducing was carried out twice. After the reaction, centrif...

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Abstract

The invention discloses a method for eliminating concentration polarization by using micro-stirring to improve membrane flux, and belongs to the application fields of functional materials and membrane engineering. The micro-stirring refers to the rotation of a micro-sized magnetic stirring bar on the membrane surface under the action of a magnetic field to promote the mixing between the liquid and the retained solute. The invention also proposes the preparation methods of different magnetic stirring bars and the effects on the membrane flux. In conclusion, the method of using micro-stirring to improve membrane flux avoids the problems of membrane surface modification and membrane device modification in the past. Therefore, it has a good application prospect in the field of membrane.

Description

technical field [0001] The invention relates to a method for improving membrane flux by using micro-stirring, and belongs to the application fields of functional materials and membrane engineering. Background technique [0002] Membrane flux refers to an important process operating parameter in the membrane separation process, which refers to the amount of fluid passing through a unit membrane area per unit time, which is jointly determined by the external driving force and the resistance of the membrane. [0003] There are many reasons that affect the membrane flux, including the influent temperature, the influent flow rate, the influent concentration, the working pressure, the properties of the membrane itself, etc. However, for a specific membrane in a specific working environment, as the separation progresses near the membrane pores, the substances that are allowed to pass through the membrane pores, and the separated substances such as ions, solutes of different molecul...

Claims

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Application Information

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Patent Type & Authority Patents(China)
IPC IPC(8): B01D61/14B01D61/20B01D65/08
CPCB01D61/145B01D61/20B01D65/08
Inventor 刘雪洋陈虹宇李卫星李博童裕佳
Owner NANJING TECH UNIV
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