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Preparation method of nanofiltration composite membrane for softening water

A water softening and composite membrane technology, applied in the field of membrane separation, can solve the problems of insufficient separation efficiency and high rejection rate of monovalent ions

Inactive Publication Date: 2020-10-20
ZHEJIANG UNIV OF TECH
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

[0004] At present, the relatively common polyethyleneimine positively charged nanofiltration membrane has a relatively high rejection rate for divalent cations, but the rejection rate for monovalent ions is also relatively high. In the advanced treatment of water quality, it is not yet ideal. separation efficiency

Method used

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  • Preparation method of nanofiltration composite membrane for softening water
  • Preparation method of nanofiltration composite membrane for softening water
  • Preparation method of nanofiltration composite membrane for softening water

Examples

Experimental program
Comparison scheme
Effect test

Embodiment 1-5

[0024] The mass volume concentration (gram / 100 milliliter) is 0.06% iodomethane and polyethyleneimine co-dissolution in water, polyethyleneimine mass volume concentration (gram / 100 milliliter) is respectively 0.2%, 0.4%, 0.6%, 0.8%, 1.0%, co-dissolved at 30°C for 12 hours to obtain a quaternized polyethyleneimine aqueous solution. The mass volume concentration (gram / 100 milliliter) is that the cross-linking agent solution of 0.1% trimesic acid and 0.15 sodium lauryl sulfate is coated on the polyethersulfone ultrafiltration membrane surface, after removing excess solution, at 30 ℃ Dry in oven. Soak the surface of the dried membrane with quaternized polyethyleneimine aqueous solution, let it stand for 3 minutes, remove the excess solution, take it out after heat treatment at 90°C for 10 minutes, and then test the membrane after soaking in deionized water for 24 hours performance.

[0025] The test liquids are 500ppm saline solution and pure water respectively, and the desalina...

Embodiment 6-10

[0028] As in the above example, 0.02% methyl iodide and 0.6% polyethyleneimine were co-dissolved in water at a mass volume concentration (g / 100 ml), and 0, 4, 8, 12, and 16 were respectively co-dissolved at 25°C. hours, a quaternized polyethyleneimine aqueous solution was obtained. The surface of the polysulfone ultrafiltration membrane is coated with a cross-linking agent solution containing sodium dodecylsulfonate and trimesic acid, wherein the mass volume concentration of sodium dodecylsulfonate (g / 100 ml) is 0.15%, and The mass volume concentration (g / 100 ml) of triformic acid is 0.1%, respectively. Dry in an oven at 30°C for 10 minutes after removing excess solution. Coat the surface of the membrane with a quaternized polyethyleneimine aqueous solution, let it stand for 5 minutes, remove the excess solution, place it in a blast drying oven at 100°C for 10 minutes, take it out, and then soak it in deionized water for 24 hours Test membrane performance. .

[0029] The t...

Embodiment 11-20

[0032] As in the above example, 0.02% methyl iodide and 0.4% polyethyleneimine were co-dissolved in water with a mass volume concentration (g / 100 ml) and co-dissolved at 25° C. for 10 hours to obtain quaternized polyethylene imine solution. The mass volume concentration (g / 100 ml) is 0.1% trimesic acid used as a cross-linking agent to infiltrate the surface of the polyethersulfone ultrafiltration membrane, and placed in an oven at 30° C. for 15 minutes. The quaternized polyethyleneimine aqueous solution was coated on the surface of the dried ultrafiltration membrane, heat-treated at 90°C for 10 minutes, and then soaked in deionized water for 24 hours to test the membrane performance.

[0033] The test solution is a mixed salt solution of 100ppm magnesium chloride solution and 100ppm calcium chloride solution and sodium chloride solution of different concentrations, and the membrane performance is tested at an operating temperature of 25°C and an operating pressure of 0.2MPa. ...

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Abstract

The invention discloses a preparation method of a nanofiltration composite membrane capable of being used for softening water. A trimesic acid crosslinking agent and polyethyleneimine are crosslinkedon the surface of an ultrafiltration membrane to obtain a composite layer, and the charge effect of the membrane surface is enhanced by quaternization, thereby enhancing the selectivity. The advantages of good hydrophilicity, strong charge property, stable film-forming property and the like of polyethyleneimine are fully exerted, and the desalination rate and the water flux are greatly improved. The membrane preparation process is simple, process parameters are easy to optimize, raw materials are cheap and easy to obtain, and expanded production of the nanofiltration composite membrane is facilitated; after amino quaternization, the charge effect is enhanced, and the membrane selectivity is further improved.

Description

technical field [0001] The invention relates to a preparation method of a nanofiltration composite membrane, in particular to a preparation method of a nanofiltration composite membrane that can be used for water softening, and belongs to the technical field of membrane separation. Background technique [0002] High-hardness water has a great impact on people's drinking water and domestic water. The increase in hardness in water is mainly caused by polyvalent metal salts such as calcium salts and magnesium salts. There is a correlation between calcium and magnesium plasma levels in drinking water and colorectal cancer, gastric cancer, breast cancer, mental disorders, and deterioration of renal function. In addition, for laundry and kitchen cleaning water, these multivalent ions can react with saponification anions, resulting in a decrease in cleaning efficiency. Long-term use of hard water will also cause problems such as scaling and corrosion of boiler pipes and other equi...

Claims

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Application Information

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IPC IPC(8): B01D71/60B01D69/12B01D69/02B01D67/00B01D61/02C02F1/44C02F5/00
CPCB01D61/027B01D67/0006B01D69/02B01D69/125B01D71/60C02F1/442C02F5/00Y02A20/131
Inventor 周勇顾凯锋高从堦
Owner ZHEJIANG UNIV OF TECH
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