CN100435920C - Method for preparing ultrafiltration film of poly-ether-sulfone and anti-protein-contamination type - Google Patents

Abstract

A process for preparing the ultrafiltering polyethersulfone membrane resisting against protein pollution includes such steps as preparing PVC solution and borax solution, washing the raw ultrafiltering polyethersulfone membrane, drying in the air, immersing in the PVC solution, washing, drying, immersing in the borax solution, washing, drying, and repeating the last 6 steps several times.

Description

A kind of preparation method of polyethersulfone anti-protein fouling ultrafiltration membrane

technical field

The invention relates to a preparation method of a polyethersulfone anti-protein pollution ultrafiltration membrane. It belongs to ultrafiltration membrane preparation technology.

Background technique

Ultrafiltration is a liquid phase sieve separation process under the driving force of static pressure difference. The separated substances are separated according to the molecular weight difference. The sieving process is related to the membrane pore size. The molecular weight cut-off of ultrafiltration is about 500 to 500,000, and it is usually used in the fields of purification, separation and concentration of macromolecular substances. The ultrafiltration process has the following advantages: (1) There is no transition between phases, and it can be separated at room temperature and low pressure, so the energy consumption is low; (2) The equipment is small in size, simple in structure, and low in investment costs; (3) Membrane separation The process is only a simple pressurized delivery of fluid, the process flow is simple, and it is easy to operate and manage; (4) There is no qualitative change in the substance during the concentration and separation process, which is suitable for the treatment of taste-preserving and heat-sensitive substances; (5) It is suitable for trace amounts in dilute solutions Recovery of precious macromolecules and concentration of low-concentration macromolecular substances; (6) Fractionation of substances with different relative molecular masses; (7) The membrane is a uniform continuum made of high molecular polymers. No impurities fall off, ensuring the purity of the filtrate. Due to the above advantages, ultrafiltration technology has broad application prospects in industrial separation processes.

The most important factor limiting the wide application of ultrafiltration technology is membrane fouling. There are many factors that affect membrane fouling, including membrane materials, operating conditions, properties of feed liquid, and so on. One of the main reasons is the adsorption of solute molecules by the membrane. At present, most of the ultrafiltration membranes used in industry are made of hydrophobic materials. In the fields of biological product separation and oily wastewater treatment, macromolecules in the treatment system are easy to adsorb on the surface of hydrophobic membranes, which affects the separation performance of ultrafiltration membranes. . Studies have shown that increasing the hydrophilicity of the membrane surface can increase its repulsion to solute molecules and reduce the adsorption of solute molecules on the membrane surface, thereby improving the anti-protein fouling performance of ultrafiltration membranes.

Polyethersulfone is a common membrane material, which has the advantages of high mechanical strength, good physical and chemical stability, excellent film-forming properties, low price and easy availability, etc., so it is widely used. However, polyethersulfone has strong hydrophobicity, and it is easy to cause a large amount of adsorption of protein or oil droplet molecules on the membrane surface, resulting in serious membrane fouling and a decrease in separation efficiency. A variety of methods have been applied in the literature to modify the surface of polyethersulfone ultrafiltration membranes to improve the hydrophilicity of the membrane surface and enhance its anti-fouling ability. Common methods such as chemical grafting, ultraviolet grafting, low temperature plasma grafting and so on. Most modification methods are complicated to operate, harsh conditions, and difficult to control the modification effect, so the development of new modification technology is of great significance; existing modifiers are mainly hydrophilic chain polymers, such as polyethylene glycol , Phospholipids. Polyvinyl alcohol has strong hydrophilicity. Studies have shown that it has excellent anti-protein and oil adsorption properties. At present, it is mostly used to improve the hydrophilicity of non-porous surfaces. Studies have also shown that polyvinyl alcohol has a huge role in the modification of porous surfaces. Development potential.

Contents of the invention

The object of the present invention is to provide a method for preparing a polyethersulfone anti-protein pollution ultrafiltration membrane. The process of the method is simple, and the ultrafiltration membrane prepared by this method has strong anti-pollution ability to protein and oil molecules.

The present invention is achieved through the following technical solutions. A preparation method of polyethersulfone anti-protein fouling ultrafiltration membrane is characterized in that it comprises the following steps:

(1) After drying polyethersulfone at 110°C to 150°C for 12 hours, dissolve it in N,N-dimethylformamide at 60°C, prepare a solution with a mass concentration of 16% to 18%, and add a mass concentration of 10 ~15% polyethylene glycol with a molecular weight of 2000 is used as a porogen, and the casting solution a is prepared after mixing and stirring sufficiently;

(2) Put the casting solution a prepared in step (1) at 50-70°C for 2-4 hours for defoaming, and after cooling to room temperature, pour the casting solution on a glass plate to scrape the film, and put it in the air After standing for 10-30 seconds, put it into a water bath to solidify to form a membrane, and soak it in deionized water for 24-36 hours to obtain a blank polyethersulfone ultrafiltration membrane b;

(3) adding polyvinyl alcohol into deionized water, stirring and dissolving at 90°C, and preparing a polyvinyl alcohol solution c with a mass concentration of 0.1-2.0%;

(4) dissolving borax and 0.001% sodium hydroxide in deionized water with a mass concentration of 0.5 to 1.0% borax solution d;

(5) Clean the surface of the blank film b obtained in step (2) with deionized water, dry the surface moisture, put it into the solution c obtained in step (3), and soak for 10 minutes;

(6) Take the membrane out of the solution c, wash the surface with deionized water, dry the water, put it into the solution d obtained in step (4), and soak for 10 minutes;

(7) Repeat steps (5) and (6) for 3 to 6 times to obtain a modified polyethersulfone anti-protein fouling ultrafiltration membrane.

The invention has the advantages of: the preparation method of the anti-pollution ultrafiltration membrane is simple and the conditions are mild; the adsorption amount of polyvinyl alcohol on the membrane surface can be controlled through the cross-linking reaction of polyvinyl alcohol by borax, and the stability of the polyvinyl alcohol modified membrane can be improved at the same time The modified membrane obtained by this method has obvious improvement in surface hydrophilicity, improves the ability to resist protein and oil molecule pollution, and has good stability at the same time.

Detailed ways

Embodiment one

Preparation of modified polyethersulfone anti-protein fouling ultrafiltration membrane (membrane 1)

Weigh 7.2 g of polyethersulfone and 26.8 g of N,N-dimethylformamide into a three-necked flask, heat and stir in a constant temperature water bath at 60° C. for about 0.5 hours. After the polyethersulfone is completely dissolved, weigh 6.0 grams of polyethylene glycol with a molecular weight of 2000 as a porogen and add it to the solution, heat and stir at 60°C for about 4 hours, and mix well to obtain the casting solution a. Let stand for degassing for 2 hours. After cooling to room temperature, pour the casting solution a on a glass plate to scrape the film, place it in the air for 10-30 seconds, then put it in a water bath to solidify to form a film, soak it in deionized water for 24-36 hours, and obtain a blank polyether Sulfone ultrafiltration membrane b;

Weigh 1.0 g of polyvinyl alcohol, add 199.0 g of deionized water, heat and stir at 90°C to prepare a polyvinyl alcohol solution c with a mass concentration of 0.5%; weigh 5 g of borax, and dissolve 10 mg of sodium hydroxide in deionized Be mixed with 1000 grams of mass concentration in water and be the borax solution d of 0.5%;

Clean the surface of the blank membrane b with deionized water, dry the surface moisture, soak in solution c for 10 minutes; then take the membrane out of solution c, wash the surface with deionized water, dry the water, and put it into solution d , soaked for 10 minutes; then the membrane was washed and soaked in solution c and solution d in turn to repeat the above process to complete 3 cycles to obtain a modified polyethersulfone ultrafiltration membrane (membrane 1).

During the preparation process of the above-mentioned ultrafiltration membrane, the reaction shown in formula 1 occurs, which promotes the preparation process:

The prepared modified polyethersulfone anti-protein fouling ultrafiltration membrane was analyzed by scanning electron microscopy, contact angle and X-ray photoelectron spectroscopy. It was found that the membrane had a typical ultrafiltration membrane composite structure, with uniform distribution of membrane pores and narrow pore size distribution. The hydrophilicity of the membrane surface is enhanced, and polyvinyl alcohol molecules exist. The pure water flux of the membrane reaches 108.8L/(m ² h), separates 1g/L bovine serum albumin buffer solution, and the rejection rate of bovine serum albumin is 100%. After hydraulic cleaning, the membrane has a higher flux Recovery rate, and the flux is still at a high level after long-term ultrafiltration operation.

Embodiment two

Preparation of modified polyethersulfone anti-protein fouling ultrafiltration membrane (membrane 2)

Weigh 7.2 g of polyethersulfone and 26.8 g of N,N-dimethylformamide into a three-necked flask, heat and stir in a constant temperature water bath at 60° C. for about 0.5 hours. After the polyethersulfone is completely dissolved, weigh 6.0 grams of polyethylene glycol with a molecular weight of 2000 as a porogen and add it to the solution, heat and stir at 60°C for about 4 hours, and mix well to obtain the casting solution a. Let stand for degassing for 2 hours. After cooling to room temperature, pour the casting solution a on a glass plate to scrape the film, place it in the air for 10-30 seconds, then put it in a water bath to solidify to form a film, soak it in deionized water for 24-36 hours, and obtain a blank polyether Sulfone ultrafiltration membrane b;

Weigh 2.0 grams of polyvinyl alcohol, add 198.0 grams of deionized water, heat and stir at 90 ° C to prepare a polyvinyl alcohol solution c with a mass concentration of 1.0%; weigh 5 grams of borax, and dissolve 10 mg of sodium hydroxide in deionized Be mixed with 1000 grams of mass concentration in water and be the borax solution d of 0.5%;

Clean the surface of the blank membrane b with deionized water, dry the surface moisture, soak in solution c for 10 minutes; then take the membrane out of solution c, wash the surface with deionized water, dry the water, and put it into solution d , soaked for 10 minutes; then the membrane was washed and soaked in solution c and solution d in turn to repeat the above process to complete 3 cycles to obtain a modified polyethersulfone ultrafiltration membrane (membrane 2).

The prepared modified polyethersulfone anti-protein fouling ultrafiltration membrane was analyzed by scanning electron microscopy, contact angle and X-ray photoelectron spectroscopy. It was found that the membrane had a typical ultrafiltration membrane composite structure, with uniform distribution of membrane pores and narrow pore size distribution. The hydrophilicity of the membrane surface is enhanced, and polyvinyl alcohol molecules exist. The pure water flux of the membrane reaches 128.7L/(m ² h), separates 1g/L bovine serum albumin buffer solution, and the rejection rate of bovine serum albumin is 100%. After hydraulic cleaning, the membrane has a higher flux Recovery rate, and the flux is still at a high level after long-term ultrafiltration operation; the oil-water emulsion prepared by separating 900ppm edible oil has a rejection rate of 100% for oil, and the flux recovery rate is higher than that of the blank polyethersulfone membrane.

Embodiment three

Preparation of modified polyethersulfone anti-protein fouling ultrafiltration membrane (membrane 3)

Weigh 7.2 g of polyethersulfone and 26.8 g of N,N-dimethylformamide into a three-necked flask, heat and stir in a constant temperature water bath at 60° C. for about 0.5 hours. After the polyethersulfone is completely dissolved, weigh 6.0 grams of polyethylene glycol with a molecular weight of 2000 as a porogen and add it to the solution, heat and stir at 60°C for about 4 hours, and mix well to obtain the casting solution a. Let stand for degassing for 2 hours. After cooling to room temperature, pour the casting solution a on a glass plate to scrape the film, place it in the air for 10-30 seconds, then put it in a water bath to solidify to form a film, soak it in deionized water for 24-36 hours, and obtain a blank polyether Sulfone ultrafiltration membrane b;

Weigh 4.0 grams of polyvinyl alcohol, add 196.0 grams of deionized water, heat and stir at 90 ° C to prepare a polyvinyl alcohol solution c with a mass concentration of 2.0%; weigh 5 grams of borax, and dissolve 10 mg of sodium hydroxide in deionized Be mixed with 1000 grams of mass concentration in water and be the borax solution d of 0.5%;

Clean the surface of the blank film b with deionized water, dry the surface water, soak in solution c for 10 minutes; then take the film from solution c, wash the surface with deionized water, dry the water, and put it into solution d , soak for 10 minutes; then wash the membrane and soak it in solution c and solution d in turn to repeat the above process, complete 3 cycles, and obtain the modified polyethersulfone ultrafiltration membrane (membrane 3).

The prepared modified polyethersulfone anti-protein fouling ultrafiltration membrane was analyzed by scanning electron microscopy, contact angle and X-ray photoelectron spectroscopy. It was found that the membrane had a typical ultrafiltration membrane composite structure, with uniform distribution of membrane pores and narrow pore size distribution. The hydrophilicity of the membrane surface is enhanced, and polyvinyl alcohol molecules exist. The pure water flux of the membrane reaches 113.0L/(m ² h), and the 1g/L bovine serum albumin buffer solution is separated, and the rejection rate of bovine serum albumin is 100%. After hydraulic cleaning, the membrane has a higher flux Recovery rate, and the flux is still at a high level after long-term ultrafiltration operation; the oil-water emulsion prepared by separating 900ppm edible oil has a rejection rate of 100% for oil, and the flux recovery rate is higher than that of the blank polyethersulfone membrane.

Embodiment four

Preparation of modified polyethersulfone anti-protein fouling ultrafiltration membrane (membrane 4)

Weigh 7.2 g of polyethersulfone and 26.8 g of N,N-dimethylformamide into a three-necked flask, heat and stir in a constant temperature water bath at 60° C. for about 0.5 hours. After the polyethersulfone is completely dissolved, weigh 6.0 grams of polyethylene glycol with a molecular weight of 2000 as a porogen and add it to the solution, heat and stir at 60°C for about 4 hours, and mix well to obtain the casting solution a. Let stand for degassing for 2 hours. After cooling to room temperature, pour the casting solution a on a glass plate to scrape the film, place it in the air for 10-30 seconds, then put it in a water bath to solidify to form a film, soak it in deionized water for 24-36 hours, and obtain a blank polyether Sulfone ultrafiltration membrane b;

Weigh 1.0 g of polyvinyl alcohol, add 199.0 g of deionized water, heat and stir at 90°C to prepare a polyvinyl alcohol solution c with a mass concentration of 0.5%; weigh 5 g of borax, and dissolve 10 mg of sodium hydroxide in deionized Be mixed with 1000 grams of mass concentration in water and be the borax solution d of 0.5%;

Clean the surface of the blank membrane b with deionized water, dry the surface moisture, soak in solution c for 10 minutes; then take the membrane out of solution c, wash the surface with deionized water, dry the water, and put it into solution d , soaked for 10 minutes; then the membrane was washed and soaked in solution c and solution d in turn to repeat the above process to complete 6 cycles to obtain a modified polyethersulfone ultrafiltration membrane (membrane 4).

The prepared modified polyethersulfone anti-protein fouling ultrafiltration membrane was analyzed by scanning electron microscopy, contact angle and X-ray photoelectron spectroscopy. It was found that the membrane had a typical ultrafiltration membrane composite structure, with uniform distribution of membrane pores and narrow pore size distribution. The hydrophilicity of the membrane surface is enhanced, and polyvinyl alcohol molecules exist. The pure water flux of the membrane reaches 84.0L/(m ² h), and the separation of 1g/L bovine serum albumin buffer solution has a rejection rate of 100% for bovine serum albumin. After hydraulic cleaning, the membrane has a higher flux Recovery rate, and the flux is still at a high level after long-term ultrafiltration operation.

Comparative example one

Preparation of polyethersulfone ultrafiltration membrane (membrane 5)

Weigh 7.2 g of polyethersulfone and 26.8 g of N,N-dimethylformamide into a three-necked flask, heat and stir in a constant temperature water bath at 60° C. for about 0.5 hours. After the polyethersulfone is completely dissolved, weigh 6.0 grams of polyethylene glycol with a molecular weight of 2000 as a porogen and add it to the solution, heat and stir at 60°C for about 4 hours, and mix well to obtain the casting solution a. Let stand for degassing for 2 hours. After cooling to room temperature, pour the casting solution a on a glass plate to scrape the film, place it in the air for 10-30 seconds, then put it in a water bath to solidify to form a film, soak it in deionized water for 24-36 hours, and obtain a blank polyether Sulfone ultrafiltration membrane (membrane 5);

The prepared blank polyethersulfone ultrafiltration membrane was analyzed by scanning electron microscopy, contact angle and X-ray photoelectron spectroscopy. It was found that the membrane had a typical composite structure of ultrafiltration membranes, and the membrane pores were evenly distributed and the pore size distribution range was narrow. The pure water flux of the membrane reaches 154.3L/(m ² h), and the 1g/L bovine serum albumin buffer solution is separated, and the rejection rate of bovine serum albumin is 100%. After hydraulic cleaning, the flux recovery rate is low.

Table 1 shows the separation characteristics of the ultrafiltration separation concentrated 1g/L bovine serum albumin buffer solution of the membranes prepared in Examples and Comparative Examples.

Table 1

Table 2 shows the separation characteristics of the 900ppm oil-water emulsion prepared by the ultrafiltration separation of the membranes prepared in the examples and comparative examples and concentrated edible oil.

Table 2

Claims (1)

1. a preparation method of polyethersulfone anti-protein fouling ultrafiltration membrane, is characterized in that comprising the following steps: (1) After drying polyethersulfone at 110°C to 150°C for 12 hours, dissolve it in N,N-dimethylformamide at 60°C, prepare a solution with a mass concentration of 16% to 18%, and add a mass concentration of 10 ~15% polyethylene glycol with a molecular weight of 2000 is used as a porogen, and the casting solution a is prepared after mixing and stirring sufficiently; (2) Put the casting solution a prepared in step (1) at 50-70°C for 2-4 hours for defoaming, and after cooling to room temperature, pour the casting solution on a glass plate to scrape the film, and put it in the air After standing for 10-30 seconds, put it into a water bath to solidify to form a membrane, and soak it in deionized water for 24-36 hours to obtain a blank polyethersulfone ultrafiltration membrane b; (3) adding polyvinyl alcohol into deionized water, stirring and dissolving at 90°C, and preparing a polyvinyl alcohol solution c with a mass concentration of 0.1-2.0%; (4) adding borax to deionized water containing sodium hydroxide mass concentration of 0.001%, to prepare a borax solution d with a mass concentration of 0.5 to 1.0%; (5) Clean the surface of the blank polyethersulfone ultrafiltration membrane b obtained in step (2) with deionized water, dry the surface moisture, put it into the polyvinyl alcohol solution c obtained in step (3), and soak for 10 minutes; (6) Take out the film from the polyvinyl alcohol solution c, clean the surface with deionized water, dry the water, put it into the borax solution d obtained in step (4), and soak for 10 minutes; (7) Repeat steps (5) and (6) for 3 to 6 times to obtain a modified polyethersulfone anti-protein fouling ultrafiltration membrane.