Preparation method of polyvinyl alcohol ultrathin selective layer nanofiltration membrane

A polyvinyl alcohol and selective layer technology, applied in chemical instruments and methods, membranes, membrane technology, etc., can solve the problems of poor mechanical properties, easy swelling, thick thickness, etc., to reduce transmission resistance, enhance mechanical strength, reduce The effect of small thickness

Active Publication Date: 2022-07-15
HARBIN INST OF TECH SHENZHEN GRADUATE SCHOOL
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  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

The thickness of the selective layer of the current PVA membrane is generally thick, and the mechanical properties are poor, and it is easy to swell in water

Method used

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  • Preparation method of polyvinyl alcohol ultrathin selective layer nanofiltration membrane
  • Preparation method of polyvinyl alcohol ultrathin selective layer nanofiltration membrane
  • Preparation method of polyvinyl alcohol ultrathin selective layer nanofiltration membrane

Examples

Experimental program
Comparison scheme
Effect test

Embodiment

[0032] Ⅰ The preparation process of polyvinyl alcohol solution is as follows:

[0033] Weigh 0.2-0.3 g of polyvinyl alcohol (with an alcoholysis degree of 99-99.4 mol%), add it to 200 ml of water, continue stirring for 3-4 h under constant temperature heating at 95-98 °C, and cool to room temperature to obtain 0.1-0.15 wt% The polyvinyl alcohol aqueous solution;

[0034] The preparation process of Ⅱ crosslinking agent hexafluorodianhydride solution is as follows:

[0035] Weigh a certain mass of hexafluorodianhydride (AR, 99%) and add it to 200ml of absolute ethanol, under constant temperature heating at 35 to 40 °C, continue stirring for 1 to 1.5 hours, and cool to room temperature to obtain a certain concentration of hexafluorodianhydride. Anhydride crosslinking agent solution;

[0036] The preparation process of Ⅲ surfactant sodium lauryl sulfate solution is as follows:

[0037] Weigh 0.3-0.4 g of sodium dodecyl sulfate (AR, 98.0%) into 200 ml of deionized water, continu...

example 1

[0043] The infrared spectrum of example 1 is as follows figure 1 As shown, among them, the characteristic peak of ester group (-COO-) appeared near 1730cm-1, indicating that polyvinyl alcohol did undergo esterification reaction with the cross-linking agent, and the cross-linking was successful.

example 2

[0044] Example 2 and the nanofiltration membrane prepared by the traditional coating and crosslinking method are as follows: pure water flux, retention effect on salt and morphology figure 2 , 3 , 4 and 5, it can be seen from the figure that the thickness of the selective layer of the polyvinyl alcohol-hexafluorodianhydride nanofiltration membrane prepared by the gradient crosslinking method is much smaller than that of the nanofiltration membrane prepared by the traditional coating and crosslinking method, and its performance better.

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Abstract

The invention relates to a preparation method of a polyvinyl alcohol ultra-thin selective layer composite nanofiltration membrane, comprising: dissolving polyvinyl alcohol powder in deionized water to obtain a polyvinyl alcohol solution; dissolving hexafluorodianhydride powder in absolute ethanol obtaining a cross-linking agent; dissolving the sodium dodecyl sulfate particles in deionized water to obtain a surfactant; firstly using the sodium dodecyl sulfate solution to infiltrate the surface of the base film for hydrophilic pretreatment; then adding the cross-linking agent hexafluoroethylene A dianhydride solution and a polyvinyl alcohol solution are introduced into the membrane surface successively, and a gradient crosslinking reaction occurs to obtain an ultra-thin selective layer nanofiltration membrane of hexafluorodianhydride polyvinyl alcohol. The invention can reduce the thickness of the nanofiltration membrane selection layer, and effectively control the mutual restriction effect between the permeation flux and the separation performance of the nanofiltration membrane.

Description

technical field [0001] The invention belongs to the technical field of nanofiltration membrane preparation, and in particular relates to a preparation method of a polyvinyl alcohol composite nanofiltration membrane with an ultra-thin selection layer. Background technique [0002] As a pressure-driven separation membrane, nanofiltration membrane has a molecular pore size between ultrafiltration membrane and reverse osmosis membrane, and has the characteristics of low operating pressure and large flux. However, in actual operation, the performance of nanofiltration membranes is limited by the trade-off effect between permeate flux and separation performance and the phenomenon of membrane fouling. Among them, adjusting the thickness of the selection layer of the nanofiltration membrane can reduce the resistance of the solution in the membrane, so that the nanofiltration membrane has a better interception efficiency for solutes and at the same time improves the permeation flux o...

Claims

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Application Information

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Patent Type & Authority Patents(China)
IPC IPC(8): B01D67/00B01D61/02B01D69/12B01D71/38C02F1/44
CPCB01D69/125B01D61/027B01D71/38C02F1/442B01D2323/30B01D2325/04B01D2323/50B01D2323/12
Inventor 邢丁予王颖李文静孙飞云沈启董文艺
Owner HARBIN INST OF TECH SHENZHEN GRADUATE SCHOOL
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