Low-pressure high-flux chlorine-containing polymer nanofiltration membrane with stable separation layer and preparation method thereof

Abstract

The invention discloses a low-pressure high-flux chlorine-containing polymer nanofiltration membrane with a stable separation layer and a preparation method thereof. The nanofiltration membrane comprises a macroporous support layer and a dense function layer, wherein the macroporous support layer and the dense function layer are connected with each other by virtue of a C-N bond; the dense function layer is made of a positive, charged or amphoteric ionic cross-linking polyamine compound; the macroporous support layer is made of a chlorine-containing polymer. The preparation method of the filtration membrane comprises the following steps: firstly coating the surface of a chlorine-containing polymer ultrafiltration membrane with the polyamine compound, carrying out heat treatment, washing the ultrafiltration membrane, then dipping the ultrafiltration membrane in a mixed solution of a cross-linking agent and a charge reagent and carrying out heat treatment again. The membrane flux of the prepared polymer nanofiltration membrane can reach 60L / m<2>.h under the pressure of 0.3MPa; the retention rate on micromolecule dye and high-valence inorganic salt can reach 90%; the chlorine-containing polymer nanofiltration membrane can be in a flat fiber ultrafiltration membrane form or a hollow fiber ultrafiltration membrane form, and has good practical prospect.

Description

technical field

[0001] The invention belongs to the technical field of membrane separation, and in particular relates to a low-pressure, high-flux chlorine-containing polymer nanofiltration membrane with a stable separation layer and a preparation method thereof. Background technique

[0002] Membrane separation technology has the advantages of high separation efficiency, easy operation, and low energy consumption, and has become one of the most important means in today's separation science. Nanofiltration is a separation technology with a separation capacity between ultrafiltration and reverse osmosis. The molecular weight cut-off is between 200-2000, and the membrane pore size is about 1nm. It can operate under low pressure and requires low equipment. It is used in the food industry and wastewater treatment. , oil exploration, pharmaceuticals and other fields have broad application prospects.

[0003] At present, there are two main preparation methods for commercial nanof...

Examples

preparation example Construction

[0048] The preparation method of the low-pressure high-flux chlorine-containing polymer nanofiltration membrane with a stable separation layer comprises the following steps:

[0049] 1) Uniformly coating the polyamine compound aqueous solution on the surface of the chlorine-containing polymer ultrafiltration membrane, and then performing the first heat treatment on the ultrafiltration membrane;

[0050] 2) The ultrafiltration membrane treated in step 1) is washed and then immersed in a mixed solution of a crosslinking agent and a charging reagent, and subjected to a second heat treatment to obtain a low-pressure high-flux polymer nanofiltration membrane with a stable separation layer.

[0051] Preferably, the polyamine compound in step 1) is selected from any one or more of tetraethylenepentamine, triethylenetetramine, polyethylene polyamine, and polyethyleneimine, and the polyamine compound solution is 10% by mass ~50% aqueous solution.

[0052] As a preference, the material...

Embodiment 1

[0060] A 15% polyethyleneimine (PEI) aqueous solution was coated on a flat polyvinyl chloride (PVC) ultrafiltration membrane, and rinsed with deionized water after the first heat treatment at 60°C for 10 hours. Then the film was immersed in 10% glutaraldehyde and 10% methacryloyloxyethyltrimethylammonium chloride (EPTAC) aqueous solution at 60°C for the second time. After heat treatment for 1 hour, a positively charged low-pressure high-flux PVC / PEI polymer nanofiltration membrane is obtained.

[0061] attached image 3 Infrared reflection spectra of the surface before and after film treatment. Compared with the PVC support layer M0, M3 after depositing the PEI layer and crosslinking with glutaraldehyde, at 3377cm -1 and 1035cm -1 Two new absorption peaks appear, corresponding to -NH of PEI 2 and -C-N- single-bond stretching vibrations, indicating the stable existence of the PEI layer; at 1546cm -1 The new absorption peak at is the C=N stretching vibration peak of the Sch...

Embodiment 2

[0073] A 40% triethylenetetramine aqueous solution was coated on a chlorinated polyethylene flat ultrafiltration membrane, and after the first heat treatment at 80°C for 2 hours, it was rinsed with deionized water. Then soak the film in 0.1% by mass percentage of dicyclopentadiene epoxide and 8% by mass percentage of 1,3-propane sultone ethanol solution, at 50°C for the second time After heat treatment for 10 hours, a negatively charged low-pressure high-flux chlorinated polyethylene / triethylenetetramine polymer nanofiltration membrane is obtained.

[0074] The prepared low-pressure high-flux polymer nanofiltration membrane with a stable separation layer has a pure water flux of 61.9L / (m 2 h), the rejection rate of 0.01mol / L sodium sulfate is 90.1%, the rejection rate of 0.01mol / L sodium chloride is 42.1%, and the rejection rate of Congo red is 99.9%. The membrane is placed at 60°C for deionization The flux and interception performance remained unchanged when the water was sh...

technical field

[0001] The invention belongs to the technical field of membrane separation, and in particular relates to a low-pressure, high-flux chlorine-containing polymer nanofiltration membrane with a stable separation layer and a preparation method thereof. Background technique

[0002] Membrane separation technology has the advantages of high separation efficiency, easy operation, and low energy consumption, and has become one of the most important means in today's separation science. Nanofiltration is a separation technology with a separation capacity between ultrafiltration and reverse osmosis. The molecular weight cut-off is between 200-2000, and the membrane pore size is about 1nm. It can operate under low pressure and requires low equipment. It is used in the food industry and wastewater treatment. , oil exploration, pharmaceuticals and other fields have broad application prospects.

[0003] At present, there are two main preparation methods for commercial nanof...

Examples

preparation example Construction

[0048] The preparation method of the low-pressure high-flux chlorine-containing polymer nanofiltration membrane with a stable separation layer comprises the following steps:

[0049] 1) Uniformly coating the polyamine compound aqueous solution on the surface of the chlorine-containing polymer ultrafiltration membrane, and then performing the first heat treatment on the ultrafiltration membrane;

[0050] 2) The ultrafiltration membrane treated in step 1) is washed and then immersed in a mixed solution of a crosslinking agent and a charging reagent, and subjected to a second heat treatment to obtain a low-pressure high-flux polymer nanofiltration membrane with a stable separation layer.

[0051] Preferably, the polyamine compound in step 1) is selected from any one or more of tetraethylenepentamine, triethylenetetramine, polyethylene polyamine, and polyethyleneimine, and the polyamine compound solution is 10% by mass ~50% aqueous solution.

[0052] As a preference, the material...

Embodiment 1

[0060] A 15% polyethyleneimine (PEI) aqueous solution was coated on a flat polyvinyl chloride (PVC) ultrafiltration membrane, and rinsed with deionized water after the first heat treatment at 60°C for 10 hours. Then the film was immersed in 10% glutaraldehyde and 10% methacryloyloxyethyltrimethylammonium chloride (EPTAC) aqueous solution at 60°C for the second time. After heat treatment for 1 hour, a positively charged low-pressure high-flux PVC / PEI polymer nanofiltration membrane is obtained.

[0061] attached image 3 Infrared reflection spectra of the surface before and after film treatment. Compared with the PVC support layer M0, M3 after depositing the PEI layer and crosslinking with glutaraldehyde, at 3377cm -1 and 1035cm -1 Two new absorption peaks appear, corresponding to -NH of PEI 2 and -C-N- single-bond stretching vibrations, indicating the stable existence of the PEI layer; at 1546cm -1 The new absorption peak at is the C=N stretching vibration peak of the Sch...

Embodiment 2

[0073] A 40% triethylenetetramine aqueous solution was coated on a chlorinated polyethylene flat ultrafiltration membrane, and after the first heat treatment at 80°C for 2 hours, it was rinsed with deionized water. Then soak the film in 0.1% by mass percentage of dicyclopentadiene epoxide and 8% by mass percentage of 1,3-propane sultone ethanol solution, at 50°C for the second time After heat treatment for 10 hours, a negatively charged low-pressure high-flux chlorinated polyethylene / triethylenetetramine polymer nanofiltration membrane is obtained.

[0074] The prepared low-pressure high-flux polymer nanofiltration membrane with a stable separation layer has a pure water flux of 61.9L / (m 2 h), the rejection rate of 0.01mol / L sodium sulfate is 90.1%, the rejection rate of 0.01mol / L sodium chloride is 42.1%, and the rejection rate of Congo red is 99.9%. The membrane is placed at 60°C for deionization The flux and interception performance remained unchanged when the water was sh...

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