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Method for reducing ion rejection rate of charged nano-filtration membrane

A technology of nanofiltration membrane and rejection rate, which is applied in the field of chemical treatment, can solve the problems that the physical structure of the nanofiltration membrane is not dense enough, the treatment result of the nanofiltration membrane is unknown, and the stability is unknown, so as to achieve the maintenance of ion rejection rate, low processing cost, The effect of increasing water flux

Active Publication Date: 2015-04-15
HANGZHOU WATER TREATMENT TECH DEV CENT
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

Formulating from scratch is feasible, but it takes a lot of time and money, and different types of formulations require very different research
At the same time, in fact, the nanofiltration membrane with low rejection rate to NaCl is often not dense enough in physical structure, which seriously affects its performance on other ions (especially MgSO 4 , CaSO 4 and Na 2 SO 4 ) and rejection of smaller molecular weight organics
[0006] Patent CN101234295A attempts to treat the nanofiltration membrane with weak alkali solution and hydrogen peroxide solution, which reduces the NaCl removal rate of the nanofiltration membrane, but this method requires 4 to 12 hours of soaking time, which is difficult to implement on a large scale on the production line. The processing results of this method on other types of nanofiltration membranes are unknown, and the stability of long-term operation is unknown

Method used

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  • Method for reducing ion rejection rate of charged nano-filtration membrane
  • Method for reducing ion rejection rate of charged nano-filtration membrane
  • Method for reducing ion rejection rate of charged nano-filtration membrane

Examples

Experimental program
Comparison scheme
Effect test

Embodiment 1

[0035]

[0036] The above table compares by different acid chloride monomers. Modification refers to the performance comparison of composite nanofiltration membranes before and after surface reaction modification of different nanofiltration membranes (different polyacyl chloride monomers used in the oil phase) with a mass concentration of 50% ethanolamine aqueous solution (reaction modification temperature 25 ° C, reaction modification Time 5min, one side coating). The results show that for the composite nanofiltration membranes of different polyacyl chlorides, the ion rejection resolution and water flux of the composite nanofiltration membranes are improved to a certain extent after the reactive molecules with hydrophilic groups or the surface modification of the solution. Taking trimesoyl chloride as an example of a multi-acid chloride monomer system, the NaCl rejection rate of the modified composite nanofiltration membrane was reduced from 75% to 55%, and NaCl2 SO 4 The...

Embodiment 2

[0038]

[0039] The above table is the performance comparison of composite nanofiltration membranes before and after surface reaction modification with different reactive molecular aqueous solutions with hydrophilic groups (solute mass concentration is 50%) (reaction modification temperature is 25°C, reaction modification time is 5min , coated on one side). The results show that the ion rejection resolution and water flux of the composite nanofiltration membrane modified by various reactive molecules with hydrophilic groups are improved to a certain extent. Under the conditions of this embodiment, the effects of diglycolamine, ethanolamine and diethanolamine are better.

Embodiment 3

[0041]

[0042] The above table shows the performance of the composite nanofiltration membrane after surface reaction modification with different concentrations of ethanolamine aqueous solution (reaction modification temperature 25°C, reaction modification time 5min, single-sided coating). The results showed that the modification effect was the best when the mass concentration of the aqueous solution of ethanolamine was between 15% and 50%.

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Abstract

The invention discloses a chemical treatment method and particularly provides a method for selectively reducing the ion rejection rate of a charged nano-filtration membrane by using surface reaction modification. The method comprises the following steps of: compounding a separation layer on a porous supporting membrane by utilizing a water / oil two-phase interface polymerization method to prepare a nano-filtration membrane; after the separation layer is reacted, immediately carrying out reaction modification on the upper surface of the separation layer by utilizing a reactive molecular solution with hydrophilic groups to obtain a modified nano-filtration membrane; and finally, rinsing unreacted objects in the modified nano-filtration membrane and then carrying out further reaction and drying in a drying box. The method disclosed by the invention has the advantages that the water passing property of the nano-filtration membrane can be effectively improved and the rejection rate of ions with great hydrated radiuses is kept; and the method is simple to operate and the treatment cost is low.

Description

technical field [0001] The invention relates to a chemical treatment method, in particular to a method for selectively reducing the ion rejection rate of a charged nanofiltration membrane by using a surface reaction modification method. technical background [0002] Membrane separation has the advantages of low energy consumption, high efficiency, low pollution, and easy operation. It is one of the most urgent technologies to solve energy, resource, and environmental problems in the 21st century. Nanofiltration membrane is a new type of separation membrane developed in the 1980s. Its pore size ranges between reverse osmosis membranes and ultrafiltration membranes (about 1nm), allowing solvent molecules or certain low-molecular-weight solutes or low-priced ions to pass through. A functional semipermeable membrane. [0003] The composite nanofiltration membrane is composed of a separation layer on a porous support membrane by means of water / oil two-phase interfacial polymeriz...

Claims

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Application Information

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Patent Type & Authority Patents(China)
IPC IPC(8): B01D71/82B01D69/12B01D69/10B01D67/00
Inventor 潘巧明李俊俊
Owner HANGZHOU WATER TREATMENT TECH DEV CENT