阅读说明：本技术 一种go-psf复合膜选择层及其制备方法和应用 (GO-PSF composite membrane selective layer and preparation method and application thereof ) 是由 周政忠 许鑫悦 吴琦刚 郑涛 袁浩然 呼和涛力 于 2020-11-25 设计创作，主要内容包括：本发明公开了一种GO-PSF复合膜选择层的制备方法,包括：取聚砜颗粒加入到二甲基乙酰胺溶液中,加入GO颗粒,超声后磁力搅拌至铸膜液灰色透明；将基膜浸泡在甘油中,保存备用；将基膜取出,去除膜表面多余的甘油,保持膜表面干燥；利用相转化法,使上述的铸膜液在上述处理好的基膜表面成膜,洗净后保存在去离子水中。本发明所制备出的GO-PSF复合薄膜增加了亲水性、抗菌性能和抗污染能力,且相较于GO-PSF共混膜,成本降低。(The invention discloses a preparation method of a GO-PSF composite membrane selective layer, which comprises the following steps: adding polysulfone particles into a dimethylacetamide solution, adding GO particles, and performing magnetic stirring after ultrasonic treatment until a casting solution is gray and transparent; soaking basement membrane in glycerol, and storing for use; taking out the base film, removing the redundant glycerol on the surface of the film, and keeping the surface of the film dry; and forming a film on the surface of the processed base film by using a phase inversion method, cleaning, and storing in deionized water. The GO-PSF composite film prepared by the invention has increased hydrophilicity, antibacterial property and anti-pollution capability, and compared with a GO-PSF blend film, the cost is reduced.)

1. A preparation method of a GO-PSF composite membrane selective layer is characterized by comprising the following steps:

adding Polysulfone (PSF) particles into a dimethylacetamide solution, adding Graphene Oxide (GO) particles, performing ultrasonic magnetic stirring until a casting solution is gray and transparent;

soaking basement membrane in glycerol, and storing for use;

taking out the base film, removing the redundant glycerol on the surface of the film, and keeping the surface of the film dry;

and forming a film on the surface of the processed base film by using a phase inversion method, cleaning, and storing in deionized water.

2. The method for preparing the selective layer of the GO-PSF composite membrane according to claim 1, wherein the polysulfone particles are dried in a vacuum drying oven at 80 ℃ for 10h before being added into a dimethylacetamide solution.

3. The method for preparing the GO-PSF composite membrane selective layer according to claim 1, wherein the mass fraction of the polysulfone in the membrane casting solution is 10-15 wt%.

4. The preparation method of the GO-PSF composite membrane selective layer according to claim 1, wherein the mass fraction of GO in the membrane casting solution is 0.02-0.1 wt%.

5. The preparation method of the GO-PSF composite membrane selective layer according to claim 1, wherein the ultrasonic time is 1-3 h.

6. The method of claim 1, wherein the selective layer of GO-PSF composite membrane is magnetically stirred at a temperature of 60 ℃.

7. A GO-PSF composite membrane selection layer prepared according to the method of any one of claims 1 to 6.

8. Use of the GO-PSF composite membrane selection layer of claim 7 in a membrane bioreactor.

Technical Field

The invention relates to a GO-PSF composite membrane selective layer and a preparation method and application thereof, belonging to the technical field of sewage treatment.

Background

Membrane Bioreactors (MBR) have become one of the most popular wastewater treatment technologies today. The membrane bioreactor integrates the biodegradation of pollutants and the membrane separation of microorganisms, and has the main advantages of small occupied area, low pollutant discharge concentration, stable operation and good water quality of MBR.

MBR can receive the pollution of microorganism different degree in the operation process, and microbial contamination mainly refers to the absorption and the gathering of microorganism and metabolite on the membrane surface, forms the biomembrane. After being adsorbed, microorganisms grow and breed rapidly in and on the membrane surface, so that the membrane flux is reduced, the flux needs to be recovered through frequent backwashing, the structure of the membrane is easy to damage, and the service life of the membrane is shortened.

Polysulfone (PSF) membrane has the advantages of high strength, good thermal stability, good oxidation resistance, good chlorine resistance, good oil removal effect and the like, is widely applied to the deep treatment of oily wastewater and other pollutants, and is easily dissolved in N-methyl-2-pyrrolidone (NMP) and N, N-Dimethylacetamide (DMAC), so polysulfone is often used as a membrane preparation material, and the surface of the polysulfone membrane is easily polluted due to the hydrophobicity of polysulfone.

As the problem of membrane fouling has been increasingly noticed, methods of surface modification of membranes have been used to reduce membrane fouling. The PVDF blending ultrafiltration membranes with different Graphene Oxide (GO) contents are prepared by Macr et al in a blending mode, the influence of GO doping on the antibacterial performance and the biological pollution resistance of the PVDF membrane is investigated through antibacterial experiments, resistance analysis tests and the like, and a good pollution resistance effect is obtained.

However, the anti-fouling performance of the membrane is largely determined by the physicochemical properties of the surface, most of the GO in the blended membrane exists in the interior of the membrane and does not increase the anti-fouling performance, and the cost of the membrane is greatly increased due to the added price of the GO. Therefore, the composite film technology is used, GO is controlled on the surface of the film, and the film cost is reduced under the condition that the anti-pollution performance is not influenced.

However, composite thin film techniques (spin coating, interfacial polymerization, etc.) reduce the pore size of the base membrane, reduce membrane flux, and are not used in MBRs. Therefore, it is necessary to protect the pores of the base film by a pretreatment technique to prevent the polymer of the composite thin film layer from penetrating and blocking the pores.

Disclosure of Invention

The invention aims to overcome the defects of the prior art and provide a GO-PSF composite membrane selection layer, a preparation method and application thereof, so that the hydrophilicity of the membrane is enhanced, the membrane pollution is reduced, and the service life of the membrane is prolonged.

In order to solve the technical problems, the invention provides a preparation method of a GO-PSF composite membrane selective layer, which comprises the following steps:

adding Polysulfone (PSF) particles into a dimethylacetamide solution, adding Graphene Oxide (GO) particles, performing ultrasonic magnetic stirring until a casting solution is gray and transparent;

soaking basement membrane in glycerol, and storing for use;

taking out the base film, removing the redundant glycerol on the surface of the film, and keeping the surface of the film dry;

and forming a film on the surface of the processed base film by using a phase inversion method, cleaning, and storing in deionized water.

Preferably, the polysulfone particles are dried in a vacuum drying oven at 80 ℃ for 10h before being added to the dimethylacetamide solution.

Preferably, the mass fraction of the polysulfone in the membrane casting solution is 10-15 wt%.

Preferably, the mass fraction of GO in the casting solution is 0.02-0.1 wt%.

Preferably, the ultrasound time is 1-3 h.

Preferably, the magnetic stirring is carried out at a temperature of 60 ℃.

The invention also provides a GO-PSF composite membrane selective layer prepared by the method.

The invention also provides application of the GO-PSF composite membrane selective layer in a membrane bioreactor.

The invention achieves the following beneficial effects:

(1) GO is selected as an anti-pollution modifier, and the hydroxyl, carboxyl, carbonyl and epoxy functional groups of GO are utilized to enhance the hydrophilicity of the membrane, reduce the membrane pollution and prolong the service life of the membrane.

(2) Because GO is high in cost, a composite film containing GO is prepared, the PSF is used as a base film, and GO-PSF is used as a selection layer. The base film and the selection layer both use PSF, which can improve compatibility and is not easy to delaminate.

(3) Because the membrane is directly scraped on the surface of the base membrane, the membrane hole is easy to block, and the flux is sharply reduced, the base membrane is soaked by glycerol. The glycerol left in the membrane holes can avoid the permeation of GO-PSF membrane liquid during membrane scraping, protect the membrane holes and reduce the blockage of the membrane holes so as to maintain a certain flux.

Drawings

FIG. 1 is a flow chart of a GO-PSF composite membrane test disclosed in the present invention;

wherein, the system comprises 1-sodium hypochlorite, 2-peristaltic pump, 3-sewage, 4-membrane, 5-membrane pump, 6-vacuum meter, 7-backwashing system, 8-suction filtration system, 9-water collecting port and 10-membrane module.

Detailed Description

The invention is further described below with reference to the accompanying drawings. The following examples are only for illustrating the technical solutions of the present invention more clearly, and the protection scope of the present invention is not limited thereby.

The invention relates to a preparation method of a GO-PSF composite membrane selective layer, which comprises the following steps: drying polysulfone in a vacuum oven for 10h, putting a certain amount of dry polymer polysulfone (8-15 wt%, the following are mass fractions), additive GO (0.02-0.1 wt%) and solvent dimethylacetamide into a conical flask, performing ultrasonic action for 1-3h, dissolving by magnetic stirring at 60 ℃ until the casting solution is transparent gray, and standing to remove bubbles. Taking out the base membrane (PSF) soaked with glycerol, removing redundant glycerol, fixing the base membrane on the surface of a glass plate, sucking the glycerol on the surface by using filter paper, pouring the casting membrane solution in front of a wet membrane preparation device, uniformly scraping the casting membrane solution on the surface of the base membrane (PSF) by using scrapers with different thicknesses (50 um, 100um and 150 um), quickly immersing the glass plate in water, carrying out phase change on polymers to form a composite membrane, and standing the composite membrane in deionized water for later use after cleaning.

As shown in fig. 1: the membrane module 10 is used for filtering sewage by the diaphragm pump 6, the sewage flows out from the water collecting port 9 of the membrane 4, particles and microorganisms are intercepted on the membrane 4, and thus, the flux is reduced.

As shown in fig. 1: after the membrane 4 is polluted, the membrane passes through a backwashing system 7, and sodium hypochlorite 1 is pumped by a peristaltic pump 2 and is backwashed through a water collecting port 9.

Example 1:

polysulfone is dried in a vacuum oven at 80 ℃ for 10 hours, polysulfone (10 wt%), GO (0.025 wt%) and a solvent dimethylacetamide are mixed and added into a conical flask, ultrasonic wave action is carried out for 120min, magnetic stirring is carried out at room temperature for dissolving until a dissolved casting liquid is transparent gray, and standing is carried out for 10 hours. Commercial films (PSF) impregnated with glycerol were taken out and films were formed on PSF base films using 50um and 100um doctor blades.

Example 2:

and (4) carrying out an anti-pollution experiment, and pumping by using a diaphragm pump for 4-5 hours to quickly pollute the membrane, wherein the flux is reduced to 66.67% of the initial flux. Preparing a 0.2% sodium hypochlorite solution, backwashing for 2 minutes, continuously testing the water flux, and increasing the membrane flux which is not modified by GO to 77.83% of the initial flux; the flux of a 50um GO-PSF membrane rose to 88.83% of the initial flux, and the flux of a 100um GO-PSF membrane rose to the sum of the initial fluxes of 92.37%. Therefore, the anti-pollution performance of the GO-PSF composite membrane is improved through the preparation of the GO-PSF composite membrane.

Example 3:

taking out a dry commercial membrane (PSF), preparing a membrane from the GO-PSF casting membrane solution on a PSF base membrane by using a scraper, installing the prepared membrane on a filter pressing experimental device, and testing that the membrane flux is reduced by 85.5% compared with the base membrane by filtering with clean water under the pressure of 0.5MPa, which indicates that the membrane hole is seriously blocked and is not suitable for MBR.

The above description is only a preferred embodiment of the present invention, and it should be noted that, for those skilled in the art, several modifications and variations can be made without departing from the technical principle of the present invention, and these modifications and variations should also be regarded as the protection scope of the present invention.