阅读说明：本技术 一种纤维增强型pvdf超滤膜及其市政污水、工业废水中的应用 (Fiber-reinforced PVDF ultrafiltration membrane and application thereof in municipal sewage and industrial wastewater ) 是由 不公告发明人 于 2019-08-28 设计创作，主要内容包括：本发明提供了一种纤维增强型PVDF超滤膜,通过在传统的PVDF膜层内部镶嵌至少两条单丝纤维,所述单丝纤维由超高分子量PVDF树脂制成,且经过PVA亲水改性。本发明制备的PVDF超滤膜改善了膜的强度和醇水通量,在市政污水、工业废水等水处理领域具有较高的应用潜力。(the invention provides a fiber reinforced PVDF ultrafiltration membrane, which is characterized in that at least two monofilament fibers are embedded in a traditional PVDF membrane layer, wherein the monofilament fibers are made of PVDF resin with ultrahigh molecular weight and are subjected to hydrophilic modification by PVA. The PVDF ultrafiltration membrane prepared by the invention improves the strength and the alcohol water flux of the membrane, and has higher application potential in the water treatment fields of municipal sewage, industrial wastewater and the like.)

1. the fiber-reinforced PVDF ultrafiltration membrane is characterized by comprising a PVDF ultrafiltration membrane layer with non-ultrahigh molecular weight and modified PVDF monofilament fibers with ultrahigh molecular weight, which are embedded in the PVDF ultrafiltration membrane layer, wherein the modified PVDF monofilament fibers with ultrahigh molecular weight are formed by extruding a PVDF material with ultrahigh molecular weight and are formed by hydrophilic modification through PVA.

2. The membrane of claim 1, wherein said ultra-high molecular weight PVDF is one having a relative molecular weight greater than 100 million.

3. The film according to claim 1, characterized in that said supramolecular PVDF monofilament fiber has a diameter of 0.08-0.15 mm.

4. The membrane as claimed in claim 1, wherein the fiber reinforced PVDF ultrafiltration membrane has a break strength of 18-27MPa, an elongation at break of 190-220% and 980-1500L/m²Pure water flux of h.

5. The film according to claim 1, characterized in that it is prepared by the following steps:

Preparing the super-molecular weight PVDF material into super-molecular weight PVDF monofilament fibers through a screw extruder;

Wetting the super-molecular-weight PVDF monofilament supporting fiber by using deionized water, placing the super-molecular-weight PVDF monofilament supporting fiber in a PVA solution with the concentration of 0.005-0.1wt% for 2-3h, taking out the super-molecular-weight PVDF monofilament supporting fiber, drying the super-molecular-weight PVDF monofilament supporting fiber after drying the super-molecular-weight PVDF monofilament supporting fiber, placing the super-molecular-weight PVDF monofilament supporting fiber in a mixed solution of glutaraldehyde and sulfuric acid for 10-20min, washing;

mixing PVDF resin, an organic solvent and a pore-forming agent in proportion to form a membrane casting solution, and defoaming in vacuum for 3-5 h;

And filtering the membrane casting solution by using a filter screen, simultaneously feeding the membrane casting solution and the super-molecular-weight PVDF monofilament fiber into a spinning jet to enable the super-molecular-weight PVDF monofilament fiber and the membrane casting solution to be compounded and formed, feeding the membrane casting solution into a coagulating bath for phase reaction and solidification to form a membrane, and winding the membrane casting solution on a winding wheel after washing to be completely solidified to form the fiber reinforced PVDF ultrafiltration membrane.

6. the membrane of claim 1, wherein the organic solvent is one or more of N-methylpyrrolidone, N-dimethylacetamide, dimethylformamide, and dimethylsulfoxide.

7. the film of claim 1, wherein the pore former is one or more of polyvinylpyrrolidone, polyethylene glycol, LiCl, and titanium dioxide.

8. the membrane according to claim 1, wherein the casting solution comprises 15-25wt% of PVDF, 50-70 wt% of an organic solvent, and 5-15 wt% of a pore forming agent.

9. The membrane of claim 1, wherein the glutaraldehyde/sulfuric acid mixture has a glutaraldehyde concentration of 3-6wt% and a sulfuric acid concentration of 1-3 wt%.

10. use of a fiber reinforced PVDF ultrafiltration membrane according to any of claims 1 to 9 in municipal and industrial wastewater.

Technical Field

The invention relates to a hollow fiber membrane, in particular to a fiber reinforced PVDF ultrafiltration membrane.

Background

Ultrafiltration is a pressurized membrane separation technique, in which small molecular solutes and solvents are passed through a special membrane with a certain pore size under a certain pressure, while large molecular solutes are not passed through the membrane and remain on one side of the membrane, thus partially purifying the large molecular substances. Ultrafiltration is one of the membrane separation techniques using pressure as the driving force. The purpose is to separate macromolecules from small molecules. The ultrafiltration device is similar to a reverse osmosis device and has the forms of a plate type, a tube type (an inner pressure tube array type and an outer pressure tube bundle type), a roll type, a hollow fiber type and the like. Compared with other forms of membranes such as flat membrane, roll membrane and the like, the hollow fiber membrane has the advantages of large loading density per unit volume and self-support. Among materials for preparing the ultrafiltration membrane again, polyvinylidene fluoride (PVDF) has excellent mechanical strength and chemical stability, can resist the corrosion of hypochlorous acid in municipal sewage, and is widely applied to pure water production and sewage treatment.

In the application process of the PVDF ultrafiltration membrane, particularly in the application of a membrane reactor, the requirement on the strength of the fiber membrane is high, but the PVDF ultrafiltration membrane prepared by the traditional method can not meet the requirement. To ameliorate such conditions, various patents and articles have proposed fiber-reinforced fiber membranes, commonly known as "concrete-type" fiber membranes. Although the strength of the membrane filaments can be improved, the application stability of the membrane is affected by the peeling phenomenon easily generated in the application process of the reinforced fibers and the membrane filaments. In view of the above, CN106731895A proposes that PVDF fiber is used as a reinforcing fiber to reinforce the strength of PVDF ultrafiltration fiber membrane, so as to achieve the purpose of homogeneous reinforcement. However, the inventors have found experimentally that PVDF-based reinforcement fibers are very susceptible to erosion in the casting solution solvent, greatly compromising the reinforcement objectives.

Disclosure of Invention

Aiming at the defects of the prior art, the technical problems to be solved by the invention are as follows: the fiber reinforced PVDF ultrafiltration membrane is provided to prevent reinforced fibers from being corroded by a solvent, and the problem of low flux of the fiber reinforced PVDF ultrafiltration membrane is solved through hydrophilic modification of the reinforced fibers.

the invention provides a fiber reinforced PVDF ultrafiltration membrane, which comprises a PVDF ultrafiltration membrane layer with non-ultrahigh molecular weight and modified PVDF monofilament fibers with ultrahigh molecular weight, wherein the modified PVDF monofilament fibers are embedded in the PVDF ultrafiltration membrane layer and are formed by extruding a PVDF material with ultrahigh molecular weight and modifying the PVDF material through PVA hydrophilicity.

Preferably, the ultra-high molecular weight PVDF is PVDF having a relative molecular weight of more than 100 ten thousand.

Preferably, the diameter of the supermolecular weight PVDF monofilament fiber is 0.08-0.15 mm.

preferably, the fiber reinforced PVDF ultrafiltration membrane has the breaking strength of 18-27MPa, the breaking elongation of 190-220 percent and the breaking elongation of 980-1500L/m²Pure water flux of h.

Preferably, the film provided by the invention is prepared by the following steps:

(1) Preparing the super-molecular weight PVDF material into super-molecular weight PVDF monofilament fibers through a screw extruder;

(2) Wetting the super-molecular-weight PVDF monofilament supporting fiber by using deionized water, placing the super-molecular-weight PVDF monofilament supporting fiber in a PVA solution with the concentration of 0.005-0.1wt% for 2-3h, taking out the super-molecular-weight PVDF monofilament supporting fiber, drying the super-molecular-weight PVDF monofilament supporting fiber after drying the super-molecular-weight PVDF monofilament supporting fiber, placing the super-molecular-weight PVDF monofilament supporting fiber in a mixed solution of glutaraldehyde and sulfuric acid for 10-20min, washing;

(3) Mixing PVDF resin, an organic solvent and a pore-forming agent in proportion to form a membrane casting solution, and defoaming in vacuum for 3-5 h;

(4) And filtering the membrane casting solution by using a filter screen, simultaneously feeding the membrane casting solution and the super-molecular-weight PVDF monofilament fiber into a spinning jet to enable the super-molecular-weight PVDF monofilament fiber and the membrane casting solution to be compounded and formed, feeding the membrane casting solution into a coagulating bath for phase reaction and solidification to form a membrane, and winding the membrane casting solution on a winding wheel after washing to be completely solidified to form the fiber reinforced PVDF ultrafiltration membrane.

Preferably, the organic solvent is one or more of N-methylpyrrolidone, N-dimethylacetamide, dimethylformamide and dimethylsulfoxide.

preferably, the pore-forming agent is one or more of polyvinylpyrrolidone, polyethylene glycol, LiCl and titanium dioxide.

Preferably, in the casting solution, the PVDF content is 15-25wt%, the organic solvent is 50-70 wt%, and the pore-forming agent is 5-15 wt%.

preferably, the concentration of the glutaraldehyde in the mixed solution of the glutaraldehyde and the sulfuric acid is 3-6wt%, and the concentration of the sulfuric acid is 1-3 wt%.

the invention has the beneficial effects that:

The PVDF reinforced fiber in the prior art is replaced by the PVDF monofilament fiber with the ultra-high molecular weight, and the technical problem that the reinforced fiber is dissolved by a solvent is solved by using the insolubility of the PVDF with the ultra-high molecular weight. In order to improve the flux of the fiber membrane, PVA is creatively utilized to carry out PVA hydrophilic modification on the PVDF monofilament fiber with the ultrahigh molecular weight, so that the water flux of the reinforced fiber membrane is obviously improved, and the application potential of the PVDF ultrafiltration membrane is improved.

Detailed Description

the present invention is specifically illustrated below with reference to specific examples.