Polyamide composite reverse osmosis membrane repairing method

A technology of reverse osmosis membrane and repair method, which is applied in the field of polyamide composite reverse osmosis membrane repair, can solve problems such as chemical modification of old and inferior membrane surface repair, waste reverse osmosis membrane originals, etc. Improves sodium ion osmotic resistance and mild conditions

Active Publication Date: 2022-07-15
ZHEJIANG SCI-TECH UNIV
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

Each cleaning will more or less affect the performance of the membrane. With the repeated cleaning of the membrane components, the final service life of the reverse osmosis membrane is often less than 3 years, resulting in a large number of waste reverse osmosis membrane components
[0004] At present, domestic and foreign articles and patents on the diazotization reaction of polyamide membranes are all applied to the performance improvement of new membranes, and do not involve the old and inferior membranes Repair Chemical Modification

Method used

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  • Polyamide composite reverse osmosis membrane repairing method
  • Polyamide composite reverse osmosis membrane repairing method
  • Polyamide composite reverse osmosis membrane repairing method

Examples

Experimental program
Comparison scheme
Effect test

Embodiment 1

[0038] The performance-deteriorated polyamide film was fixed in a Teflon frame with an inner frame size of 10 × 20 cm, and placed for use. Concentrated hydrochloric acid was added dropwise to deionized water to prepare an aqueous hydrochloric acid solution with pH=1.02. Weigh 0.18 g of solid sodium nitrite in a beaker with a stirring magnet, pour into a pH=1.02 hydrochloric acid solution to a total mass of 60.0 g, and prepare an aqueous solution of sodium nitrite with a concentration of 0.3 wt%. Stir on a magnetic stirrer for 30s, and prepare the diazotization reagent. Pour the diazotization reagent onto the membrane surface, let it stand for 10 min at room temperature of 20°C, pour off the diazotization reagent on the membrane surface, put the polyamide membrane with deteriorated performance after the surface diazotization into ionized water, and soak it in ionized water. Put it in a container with ultraviolet light for 3 hours, and finally wash it with deionized water and s...

Embodiment 2

[0042] Take three polyamide films with deteriorated performance, respectively fix them in a PTFE frame with an inner frame size of 10×20 cm, and place them for use. Concentrated hydrochloric acid was added dropwise to deionized water to prepare an aqueous hydrochloric acid solution with pH=3.00. Weigh 0.15 g of solid sodium nitrite into a beaker with a stirring magnet, pour into a pH=3.00 hydrochloric acid solution to a total mass of 150.0 g, and prepare an aqueous solution of sodium nitrite with a concentration of 0.1 wt%. Stir on a magnetic stirrer for 30s, and prepare the diazotization reagent. Pour the diazotization reagent on the 3 membrane surfaces on average, and let stand for 5, 10 and 20 minutes at room temperature and 20°C, respectively. After the diazotization reagent is poured off the membrane surface, the performance of the polyamide after the surface diazotization is degraded. The membrane was soaked in ionized water, placed in a container with ultraviolet light...

Embodiment 3-4

[0046] Except that the pH was changed to the pH described in Table 1, the other procedures were the same as those in Example 1.

[0047] [Table 1]

[0048] pH Average water flux (l / m 2 .h)

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Abstract

The invention relates to a method for repairing a polyamide composite reverse osmosis membrane. The method comprises the following steps: firstly, carrying out membrane surface diazotization reaction on the polyamide reverse osmosis membrane with degraded performance by using an acid solution containing nitrite, controlling the pH (Potential of Hydrogen) range to be 0.5-3.0 and the concentration of sodium nitrite or potassium nitrite to be 0.05-2.00 wt%, and controlling the reaction mode to be single-sided coating or double-sided soaking for 5-30 minutes; and then carrying out 365 nm ultraviolet light illumination treatment on the diazotized membrane surface for 1-5 hours. The method has the advantages that the diazotization reaction is utilized to reconstruct the aniline structure contained in the polyamide reverse osmosis membrane separation layer with degraded performance, and more cis-azo structures are obtained on the membrane surface through simple ultraviolet irradiation, so that the permeation resistance of the separation layer to sodium ions is improved, the effect of repairing the desalination performance of the membrane is realized, and the service life of the membrane is prolonged. And the process is simple, wide in application range and easy for industrial application.

Description

technical field [0001] The invention relates to a method for repairing a polyamide composite reverse osmosis membrane, in particular to a method for in-situ performance repairing of a polyamide composite reverse osmosis membrane with deteriorated performance, belonging to the technical field of separation membrane preparation, and can The separation performance of the polyamide composite reverse osmosis membrane can be repaired in situ to prolong the service life of the membrane and reduce the use cost of the polyamide reverse osmosis membrane. Background technique [0002] Reverse osmosis technology is essentially a pressure-driven membrane separation process. During the operation of reverse osmosis, membrane fouling is inevitable. According to the different types of pollutants, it can be divided into three categories: organic pollution, inorganic pollution and microbial pollution. When the membrane fouling reaches a certain level, most of the pollutants can be effectivel...

Claims

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Application Information

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Patent Type & Authority Applications(China)
IPC IPC(8): B01D65/10
CPCB01D65/108
Inventor 俞三传刘宇鹏刘梅红
Owner ZHEJIANG SCI-TECH UNIV
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