CN1954901A - Polyester amide reverse osmosis composite membrane and preparation method thereof - Google Patents

Abstract

A composite reverse osmosis polyester-amide membrane is composed of a porous supporting layer, and a compact polyester-amide surface layer prepared by interface polymerization between aminoglucose or aminobiglucose or the mixture of aminoglucose and metaphenyldiamine and the polyatomic acyl chloride. Its preparing process includes such steps as immersing the one surface of polysulfone film in the aqueous solution of amino monomer, dripdrying, interface polymerization reaction on the solution of polyatomic acyl chloride, drying, heat treating and rinsing in deionized water. It has high water throughput.

Description

Polyester amide reverse osmosis composite membrane and preparation method thereof

technical field

The invention relates to a reverse osmosis composite membrane and a preparation method thereof, in particular to a polyester amide reverse osmosis composite membrane and a preparation method thereof.

Background technique

As one of the most advanced membrane separation technologies in the world, reverse osmosis has the advantages of high purification rate and low cost, and is widely used in desalination of seawater and brackish water, preparation of pure water and ultrapure water, industrial water treatment, waste water resources chemical and other fields. Reverse osmosis membrane is the core of reverse osmosis technology. In 1960, Loeb and Sourirajan of the University of California made the world's historic high desalination (98.6%), high flux (259L/d·m ² under 10.1MPa) asymmetric cellulose acetate reverse osmosis membrane , greatly promoted the development of reverse osmosis membrane technology. In 1978, scholars such as JECadotte in the United States made a major breakthrough in the preparation technology of reverse osmosis composite membranes and research on functional materials. They researched and developed the first generation of aromatic polyamide reverse osmosis composite membranes. It has the advantages of large flux and low operating pressure requirements. The reverse osmosis composite membrane is formed by loading ultra-thin functional skin materials on porous supports through different methods. The membrane material and support can be selected separately, which is conducive to the optimization of membrane performance. In 1980, the American Filmtec company launched the FT-30 high-performance reverse osmosis composite membrane, which realized the commercialization of the reverse osmosis composite membrane technology, thus making the reverse osmosis composite membrane technology an epoch-making progress.

Aromatic polyamide membrane has high desalination rate, large flux, biodegradation resistance, and good mechanical, thermal and chemical stability. It is currently one of the two most important reverse osmosis membranes in the world, but its oxidation resistance and anti-pollution ability poor. At present, the oxidation resistance of aromatic polyamide reverse osmosis composite membranes is usually improved by modifying the membrane surface and developing new polymer monomers and polymerization processes. The pollution-resistant low-pressure reverse osmosis composite membrane LF10 series launched by Japan's Nitto Denko in 1997 is to compound a layer of PVA on the surface of the traditional aromatic polyamide membrane, which not only weakens the negative charge of the membrane surface but also improves the hydrophilicity of the membrane. and chlorine resistance. However, modification on the membrane surface can easily lead to a decrease in membrane water flux. Kim et al. mixed polyamine and polyphenol and then carried out single-sided interfacial polymerization with polyacyl chloride solution, that is, introduced ester functional bonds into polyamide, which greatly improved its chlorine resistance. But other properties such as salt rejection and water flux are not ideal.

Contents of the invention

In view of the above problems, the object of the present invention is to provide a polyester amide reverse osmosis composite membrane with high desalination rate, high flux, and oxidation resistance, and to provide a preparation method thereof.

The polyester amide reverse osmosis composite membrane of the invention comprises a porous support layer and a dense polyester amide separation skin layer.

The porous support layer may be polysulfone, polyethersulfone, sulfonated polysulfone or sulfonated polyethersulfone;

The polyester amide separation cortex is obtained by interfacial polymerization of glucosamine, glucosamine or a mixture of glucosamine and m-phenylenediamine and polyacyl chlorides;

The thickness of the polyester amide separation skin layer is between 50nm and 200nm.

The preparation method of polyester amide reverse osmosis composite membrane comprises the following steps:

(1) Immerse one side of the polysulfone support membrane in an aqueous solution of 2% amino monomer;

(2) After the surface is drained, carry out interfacial polymerization reaction with 0.1～0.2% polyacyl chloride solution;

(3) Dry in the air for 1 to 5 minutes;

(4) Heat treatment at 50-100°C for 3-10 minutes;

(5) Rinse with deionized water to prepare a reverse osmosis composite membrane.

Reverse osmosis composite membrane performance test:

The performance of the membrane was tested under the conditions of a sodium chloride aqueous solution with a concentration of 20000 mg/L, an operating pressure of 1.6 MPa, and a temperature of 25 °C. The calculation formulas of salt rejection rate (R) and water flux (J) are:

Detailed ways

The present invention will be further described below in conjunction with specific examples.

Example 1

2% (wt %) glucosamine and 0.1% (wt %) sodium lauryl sulfate are made into water phase solution, adjust pH=12 with sodium hydroxide; Dissolve trimesoyl chloride (TMC) in n-hexane and prepare Into a 0.1% (wt%) organic phase solution. Immerse one side of the polysulfone support membrane in 2% aqueous phase solution for 3 minutes; drain the excess aqueous solution and react with the organic phase for 30 seconds; drain the organic phase and dry it in the air for 1 minute; Heat treatment at 75° C. for 3 minutes in an oven; rinse with deionized water to prepare a reverse osmosis composite membrane.

The reverse osmosis composite membrane prepared above was dried, and its infrared absorption was measured with an attenuated total reflection Fourier transform infrared spectrometer. The results showed that there were absorptions at 1663cm ^-1 and 1540cm ^-1 , which were characteristic peaks of amide I band and amide II band respectively, which proved the formation of amide bonds. The absorption peak of C ₆ hydroxyl group at 1013cm ^-1 disappeared, and the absorption peak of ester group COC appeared at 1540cm ^-1 , which proved the formation of ester group.

Example 2

Following the same steps as in Example 1, a reverse osmosis composite membrane was prepared. The aqueous phase consists of: 1.2% (wt%) m-phenylenediamine, 0.8% (wt%) glucosamine and 0.1% (wt%) sodium lauryl sulfate, and adjust pH=12 with sodium hydroxide; the organic phase is 0.1% (wt%) TMC is dissolved in n-hexane and is formulated; the polysulfone support membrane is immersed in the aqueous phase solution on one side for 3 minutes; the excess aqueous solution is drained, and the organic phase is reacted for 60 seconds; the organic phase is drained , and dried in air for 3 minutes; heat treated in a blast drying oven at 85° C. for 5 minutes; rinsed with deionized water to prepare a reverse osmosis composite membrane.

According to the method described above, its performance was measured. In an aqueous sodium chloride solution with a concentration of 20,000 mg/L, an operating pressure of 1.6 MPa, and a temperature of 25°C, the flux is 29.3 L/m ² ·h, and the desalination rate is 98.0.

Example 3

Following the same steps as in Example 1, a reverse osmosis composite membrane was prepared. The aqueous phase consists of: 1.2% (wt%) m-phenylenediamine, 0.8% (wt%) glucosamine and 0.1% (wt%) sodium lauryl sulfate, and adjust pH=12 with sodium hydroxide; the organic phase is The TMC of 0.2% (wt%) is dissolved in C ₁₂ mineral spirits and is made up; The polysulfone supporting membrane is immersed in the water phase solution on one side, time 3 minutes; Drain excess aqueous solution, react with organic phase for 60 seconds; Drain organic phase, and dried in the air for 5 minutes; heat-treated in a blast oven at 85° C. for 10 minutes; rinsed with deionized water to prepare a reverse osmosis composite membrane.

According to the method described above, its performance was measured. In an aqueous sodium chloride solution with a concentration of 20,000 mg/L, an operating pressure of 1.6 MPa, and a temperature of 25°C, the flux is 20.9 L/m ² ·h, and the desalination rate is 98.6.

Comparative example 1

Following the same steps as in Example 1, a reverse osmosis composite membrane was prepared. First 2% (wt%) triethylamine was dissolved in deionized water, and the pH=8 was adjusted with hydrochloric acid; then 2% (wt%) m-phenylenediamine and 0.1% (wt%) sodium lauryl sulfate were dissolved Make water phase therein; The TMC that organic phase is 0.2% (wt%) is dissolved in C ₁₂ solvent naphtha and is made into; Make polysulfone support membrane one-sided immersion in the water phase solution, time 3 minutes; Drain excess aqueous solution, React with the organic phase for 30 seconds; drain the organic phase and dry in the air for 1 minute; heat treat in a blast drying oven at 75° C. for 10 minutes; rinse with deionized water to prepare a reverse osmosis composite membrane.

According to the method described above, its performance was determined. In an aqueous sodium chloride solution with a concentration of 20,000 mg/L, an operating pressure of 1.6 MPa, and a temperature of 25°C, the flux is 15.4 L/m ² ·h, and the desalination rate is 98.1.

Example 4

The reverse osmosis composite membranes prepared in Example 3 and Comparative Example 1 were immersed in a sodium hypochlorite solution containing 1000 ppm available chlorine for 5 hours, taken out, and washed with deionization. The flux and desalination rate were measured in an aqueous sodium chloride solution with a concentration of 20000mg/L, an operating pressure of 1.6MPa, and a temperature of 25°C.

The results are shown in Table 1:

Table 1 Oxidation resistance test results of reverse osmosis composite membranes Membrane serial number initial performance Performance after treatment with 5000ppm·h sodium hypochlorite R(%) J(L/m ² ·h) R(%) J(L/m ² ·h) Example 3 98.6 20.9 97.6 23.2 Comparative example 1 98.1 15.4 93.7 27.9

As can be seen from the above experimental results, in the case of the same high desalination rate (> 98%), the polyester amide reverse osmosis composite membrane has a higher water flux than the aromatic polyamide reverse osmosis composite membrane; and chlorine resistance Oxidation is also better.

Claims (5)

1. a polyester amide reverse osmosis composite membrane is characterized in that it comprises a porous support layer and a dense polyester amide separation cortex. 2. The reverse osmosis composite membrane according to claim 1, characterized in that the porous support layer can be polysulfone, polyethersulfone, sulfonated polysulfone or sulfonated polyethersulfone. 3. reverse osmosis composite membrane according to claim 1, is characterized in that described polyester amide separation cortex is obtained by interfacial polymerization by the mixture of glucosamine, glucosamine or glucosamine and m-phenylenediamine and polyacyl chloride . 4. The reverse osmosis composite membrane according to claim 1 or 3, characterized in that the thickness of the polyester amide separation skin layer is between 50-200 nm. 5. according to the preparation method of the described polyester amide reverse osmosis composite membrane of right 1, comprise the following steps: (1) Immerse one side of the polysulfone support membrane in an aqueous solution of 2% amino monomer; (2) After the surface is drained, carry out interfacial polymerization reaction with 0.1～0.2% polyacyl chloride solution; (3) Dry in the air for 1 to 5 minutes; (4) Heat treatment at 50-100°C for 3-10 minutes; (5) Rinse with deionized water to prepare a reverse osmosis composite membrane.