CN109647205B

CN109647205B - Method for improving chlorine resistance of hollow fiber nanofiltration membrane

Info

Publication number: CN109647205B
Application number: CN201811606394.XA
Authority: CN
Inventors: 王春浩; 胡晓宇; 梁恩宾
Original assignee: Tianjin Motimo Membrane Technology Co Ltd
Current assignee: Tianjin Motimo Membrane Technology Co Ltd
Priority date: 2018-12-27
Filing date: 2018-12-27
Publication date: 2021-08-13
Anticipated expiration: 2038-12-27
Also published as: CN109647205A

Abstract

The invention discloses a method for improving chlorine resistance of a hollow fiber nanofiltration membrane. The invention is carried out according to the following steps: pouring the water phase A into a hollow fiber nanofiltration component, soaking for 1-4 h at the pressure of 0.5 Mpa, pouring out, adding the water phase B into the hollow fiber nanofiltration component, soaking for 5-30 min, pouring out, and washing with RO water at the pressure of 0.5 Mpa until the water production conductance is less than 10 uS, thus completing the process; the water phase A consists of 5-20 parts by mass of an end-capping agent and 100 parts by mass of deionized water; and the water phase B consists of 1-5 parts by mass of a terminator and 100 parts by mass of deionized water. The method is simple, efficient, durable in effect, low in cost and suitable for industrialization.

Description

Method for improving chlorine resistance of hollow fiber nanofiltration membrane

Technical Field

The invention relates to the technical field of membranes, in particular to a method for improving chlorine resistance of a hollow fiber nanofiltration membrane.

Background

In the prior art, a protective layer is formed on the surface of a nanofiltration or reverse osmosis membrane by adopting an aldehyde-amine condensation reaction, so that the corrosion of chlorine-containing medicines such as sodium hypochlorite and the like is delayed, such as CN 103331110A and CN 105413499A. However, the aldehyde-amine condensation is a reversible reaction and the durability is questionable. However, CN 104379243A, CN 107899434A and the like rely on adsorption to different degrees, and the durability of the effect is questionable. It is a good idea to change monomers or other raw materials for patents CN 104023830 a, CN 106669438A, etc. to fundamentally reduce the possibility of corrosion from the viewpoint of the structure of the desalination function layer. But cannot be used for commercial films purchased due to the need to change the pre-process parameters of the formulation, process, etc. In addition, some patents have complicated processes or long processing time, which is not suitable for industrialization, such as CN 108176246 a and CN 103272498A.

Disclosure of Invention

The invention aims to solve the technical problem of overcoming the defects in the prior art and provides a method for improving the chlorine resistance of a hollow fiber nanofiltration membrane.

The invention relates to a method for improving chlorine resistance of a hollow fiber nanofiltration membrane, which is realized by the following technical scheme that a water phase A is poured into a hollow fiber nanofiltration component and is soaked for 1-4 h under the pressure of 0.5 MPa, then the water phase A is poured out, then a water phase B is added into the hollow fiber nanofiltration component and is soaked for 5-30 min, and after the water phase B is poured out, RO water is used for washing under the pressure of 0.5 MPa until the water production conductance is less than 10 uS, so that the method is finished; the water phase A consists of 5-20 parts by mass of an end-capping agent and 100 parts by mass of deionized water; and the water phase B consists of 1-5 parts by mass of a terminator and 100 parts by mass of deionized water.

The end capping agent is acetic anhydride, propionic anhydride, butyric anhydride, beta-propiolactone, butyrolactone, valerolactone or caprolactone.

The terminator is sodium hydroxide or potassium hydroxide.

Compared with the prior art, the invention has the beneficial effects that:

the method is simple, efficient, durable in effect, low in cost and suitable for industrialization.

Detailed Description

The present invention will be described in further detail with reference to specific examples. It should be understood that the specific embodiments described herein are merely illustrative of the invention and are not intended to limit the invention.

Example 1

An aqueous phase A: 5 parts of acetic anhydride and 100 parts of deionized water.

And (3) water phase B: 1 part by mass of sodium hydroxide and 100 parts by mass of deionized water.

And pouring the water phase A into the assembly, and soaking for 4 hours under the pressure of 0.5 MPa. Pouring out, adding water phase B, and soaking for 30 min. And (4) flushing with RO water under 0.5 MPa until the water production conductance is less than 10 uS, and immersing in water to be tested.

Example 2

An aqueous phase A: 15 parts of propionic anhydride and 100 parts of deionized water.

And (3) water phase B: 2 parts of sodium hydroxide and 100 parts of deionized water.

And pouring the water phase A into the assembly, and soaking for 1 h under the pressure of 0.5 MPa. Pouring out, adding water phase B, and soaking for 30 min. And (4) flushing with RO water under 0.5 MPa until the water production conductance is less than 10 uS, and immersing in water to be tested.

Example 3

An aqueous phase A: 5 parts of beta-propiolactone and 100 parts of deionized water.

And pouring the water phase A into the assembly, and soaking for 1 h under the pressure of 0.5 MPa. Pouring out, adding water phase B, and soaking for 10 min. And (4) flushing with RO water under 0.5 MPa until the water production conductance is less than 10 uS, and immersing in water to be tested.

Example 4

An aqueous phase A: 10 parts of butyl lactone and 100 parts of deionized water.

And (3) water phase B: 5 parts of potassium hydroxide and 100 parts of deionized water.

And pouring the water phase A into the assembly, and soaking for 1 h under the pressure of 0.5 MPa. After pouring out, add water phase B and soak for 5 min. And (4) flushing with RO water under 0.5 MPa until the water production conductance is less than 10 uS, and immersing in water to be tested.

Example 5

An aqueous phase A: 10 parts of caprolactone and 100 parts of deionized water.

And (3) water phase B: 1 part by mass of potassium hydroxide and 100 parts by mass of deionized water.

Comparative example 1

The same procedure as in example 1 was repeated except that the aqueous phase A was not used.

Comparative example 2

The same procedure as in example 1 was repeated except that the aqueous phase B was not used.

Comparative example 3

An aqueous phase A: 1 part by mass of acetic anhydride and 100 parts by mass of deionized water.

The aqueous phase A was poured into the module and soaked for 1 h without pressure. Pouring out, adding water phase B, and soaking for 30 min. And (4) flushing with RO water under 0.5 MPa until the water production conductance is less than 10 uS, and immersing in water to be tested.

And (3) carrying out residual chlorine tolerance test on each nanofiltration membrane by the following method:

soaking a nanofiltration membrane in an aqueous solution with the residual chlorine content of 3000 ppm for 10 hours, then washing the nanofiltration membrane by using deionized water until the water-producing conductance is less than 10 uS, and immersing the nanofiltration membrane in water to be detected.

The separation performance of each nanofiltration membrane is tested, and the method comprises the following steps:

testing liquid: with 2000 mg/L magnesium sulfate (MgSO)₄) And (4) testing the solution.

The operation parameters are as follows: a nanofiltration membrane evaluator is adopted for testing, the pressure is 0.5 MPa, the temperature is 25 ℃, the pH =7.0, and the recovery rate is 15%.

Calculating the formula:

retention rate R = (C)_I-C_O)/C_I100% of C_IFor water conductivity, C_OConducting for water outlet;

TABLE 1 nanofiltration Membrane chlorine resistance comparison

	MgSO₄(%) before testing	MgSO₄After the (%) -test
			Example 1	97.6	95.1
Example 2	97.2	96.3
			Example 3	96.5	96.6
Example 4	98.0	96.8
			Example 5	97.3	96.1
Comparative example 1	97.5	23.1
			Comparative example 2	97.4	92.7
Comparative example 3	97.6	56.8

The chlorine resistance of the nanofiltration membrane is compared and shown in the table, and the conclusion is that: after the treatment by using the end-capping agent, the chlorine resistance of the nanofiltration membrane can be improved to 30000 ppm h, and the residual chlorine resistance of the nanofiltration membrane is improved by 10 times compared with 3000 ppm h of a common nanofiltration membrane, such as example 1 and comparative example 1. The terminating agent can further improve the effect of the capping agent, as in comparative example 2. When the concentration of the terminator is too low and the treatment time is too short, the improvement of the residual chlorine resistance is limited as in comparative example 3.

The foregoing is only a preferred embodiment of the present invention, and it should be noted that, for those skilled in the art, various modifications and decorations can be made without departing from the principle of the present invention, and these modifications and decorations should also be regarded as the protection scope of the present invention.

Claims

1. A method for improving the chlorine resistance of a hollow fiber nanofiltration membrane is characterized by comprising the following steps: pouring the water phase A into a hollow fiber nanofiltration component, soaking for 1-4 h at the pressure of 0.5 Mpa, pouring out, adding the water phase B into the hollow fiber nanofiltration component, soaking for 5-30 min, pouring out, and washing with RO water at the pressure of 0.5 Mpa until the water production conductance is less than 10 mu S, thus completing the process; the water phase A consists of 5-20 parts by mass of an end-capping agent and 100 parts by mass of deionized water; the water phase B consists of 1-5 parts by mass of a terminator and 100 parts by mass of deionized water;

the end capping agent is acetic anhydride, propionic anhydride, butyric anhydride, beta-propiolactone, butyrolactone, valerolactone or caprolactone; the terminator is sodium hydroxide or potassium hydroxide.