CN106345308A - Preparation method for polyesteramide compound nanofiltration membrane with strong chlorine resistance and pollution resistance - Google Patents

Abstract

The invention discloses a preparation method of a polyester amide composite nanofiltration membrane with strong chlorine resistance and pollution resistance. In the method, serinol is used as a reaction monomer in the water phase, and 4-dimethylaminopyridine is added into the water phase at the same time As a phase transfer catalyst and acylation catalyst, a novel polyester amide composite nanofiltration membrane was prepared by interfacial polymerization of serinol and polyacyl chlorides on a porous support layer. In the present invention, a novel polyester amide composite nanofiltration membrane is obtained through interfacial polymerization reaction of serinol and polyacyl chlorides on a porous support layer under the catalysis of 4-dimethylaminopyridine. It has the characteristics of good chlorine, strong hydrophilicity, strong anti-pollution ability and strong solute interception ability, and the preparation process is simple and mild, which is suitable for industrial production.

Description

A preparation method of polyester amide composite nanofiltration membrane with strong chlorine resistance and anti-pollution

technical field

The invention belongs to the technical field of membrane separation, and relates to a preparation method of a polyester amide composite nanofiltration membrane with strong chlorine resistance and strong pollution resistance.

Background technique

With the development of economy, the increase of population and the aggravation of water pollution, many countries in the world are facing the problem of water shortage. Therefore, when additional clean water resources cannot be replenished, the purification of existing water resources is an important measure to deal with the water resource crisis. Nanofiltration membrane (NF) is a special membrane material between ultrafiltration membrane and reverse osmosis membrane. It can intercept small molecular organic matter, has partial desalination ability, and has the characteristics of high flux and low energy consumption. At present, It has been used in many fields such as water softening, brackish water desalination, advanced sewage treatment, pharmaceutical and biological purification, and food processing.

Polyamide composite nanofiltration membranes prepared by interfacial polymerization of polyamines and polyacyl chlorides on the support layer have occupied a dominant position in the market share of nanofiltration membranes. However, the serious membrane fouling problem and poor chlorine resistance are the main obstacles limiting its further application. Therefore, the development of new nanofiltration membranes with anti-pollution ability and strong chlorine resistance is the focus of many researchers. Existing studies have shown that polyamide composite nanofiltration membranes prepared from polyamines and polyacyl chlorides usually have high pollutant removal and desalination capabilities, but their anti-pollution and chlorine resistance are poor; Polyester composite nanofiltration membranes prepared by polyols and polyacyl chlorides or polyacids usually have stronger anti-fouling ability and chlorine resistance, but their membrane pores are larger, and the pollutant retention capacity and desalination rate are lower. How to combine the advantages of polyamide nanofiltration membrane and polyester nanofiltration membrane to prepare a composite nanofiltration membrane with strong anti-pollution ability, strong chlorine resistance and strong pollutant removal ability is our research goal.

Contents of the invention

The purpose of the present invention is to provide a preparation method of a novel polyester amide composite nanofiltration membrane with strong chlorine resistance and anti-pollution, which combines the advantages of polyamide nanofiltration membrane and polyester nanofiltration membrane to solve the existing commercial problems. Nanofiltration membranes are prone to fouling and poor chlorine resistance.

The purpose of the present invention is achieved through the following technical solutions:

A preparation method of a polyester amide composite nanofiltration membrane with strong chlorine resistance and anti-pollution, using serinol as a reaction monomer in the water phase, and simultaneously adding 4-dimethylaminopyridine to the water phase as a phase transfer catalyst and acylation Catalyst, through the interfacial polymerization reaction of serinol and polyacyl chloride on the porous support layer to prepare a new type of polyester amide composite nanofiltration membrane, the specific steps are as follows:

1. Preparation of aqueous phase solution: add 0.5~5% (w/v) serinol to pure water, and add 0.05~0.5% (w/v) 4-dimethylaminopyridine at the same time for phase transfer and acylation Catalyst, after fully stirring and dissolving, use triethylamine to adjust the pH value of the solution to 11.3~12.0;

2. Prepare the organic phase solution: use one or more of n-hexane, cyclohexane, toluene, n-heptane or n-octane as the organic solvent, and add 0.01~0.5% (w/v) of Polyacid chlorides;

3. With polysulfone, polyethersulfone, sulfonated polyethersulfone or polypropylene porous ultrafiltration membrane as the supporting layer, first pour the aqueous phase solution onto the surface of the supporting layer and soak for 1 to 10 minutes, then pour off the aqueous phase solution and dry it. Remove excess moisture from the membrane surface, then pour the organic phase solution onto the membrane surface, and react for 10-120 seconds. After the reaction, fully rinse the membrane surface with an organic solvent to remove unreacted monomers;

4. Heat-treat the film after washing with organic solvent at 20-80°C for 5-20 minutes;

5. Finally, the membrane is fully washed with pure water to obtain a polyester amide composite nanofiltration membrane.

In the present invention, a novel polyester amide composite nanofiltration membrane is obtained through the interfacial polymerization reaction of serinol and polyacyl chlorides on the porous support layer under the catalysis of 4-dimethylaminopyridine. It has the characteristics of good chlorine, strong hydrophilicity, strong anti-pollution ability and strong solute interception ability, and the preparation process is simple and mild, which is suitable for industrial production.

Description of drawings

Fig. 1 is serinol molecular structural formula;

Figure 2 is the atomic force microscope morphology of the novel polyester amide composite nanofiltration membrane;

Figure 3 is the scanning electron microscope morphology of the novel polyester amide composite nanofiltration membrane;

Figure 4 is the infrared spectrum of the novel polyester amide composite nanofiltration membrane.

detailed description

The technical solution of the present invention will be further described below in conjunction with the accompanying drawings, but it is not limited thereto. Any modification or equivalent replacement of the technical solution of the present invention without departing from the spirit and scope of the technical solution of the present invention should be covered by the present invention. within the scope of protection.

Embodiment 1: This embodiment provides a method for preparing a polyester amide composite nanofiltration membrane with strong chlorine resistance and anti-pollution, and the specific steps are as follows:

1. Preparation of aqueous phase solution: add 2% (w/v) serinol (its structural formula is shown in Figure 1) to pure water, and add 0.2% (w/v) 4-dimethylaminopyridine at the same time as Phase transfer and acylation catalyst, after fully stirring and dissolving, use triethylamine to adjust the pH value of the solution to 11.5;

2. Prepare the organic phase solution: use n-hexane as the organic solvent, and add 0.1% (w/v) polyacyl chloride to the organic solvent;

3. With the polyethersulfone porous ultrafiltration membrane as the supporting layer, first pour the aqueous phase solution onto the surface of the supporting layer and soak for 2 minutes, then pour off the aqueous phase solution and remove excess water on the membrane surface, and then pour the organic phase solution onto the membrane surface, and react for 60 seconds. After the reaction, use an organic solvent to fully rinse the membrane surface to remove unreacted monomers;

4. Heat-treat the film after washing with organic solvent at 50°C for 10 minutes;

5. Finally, the membrane is fully washed with pure water to obtain a polyester amide composite nanofiltration membrane.

Figure 2A shows the topography of the porous support layer atomic force microscope without reaction, and Figure 2B shows the topography of the polyester amide composite nanofiltration membrane obtained after the interfacial polymerization is completed, as can be seen from Figure 2, through the above reaction steps , successfully formed a concave-convex polyester amide active layer on a relatively smooth support layer.

Figure 3A and B are scanning electron microscope topography images of the porous support layer and the polyester amide composite nanofiltration membrane, respectively, and the comparison between the two also confirms the formation of the polyester amide active layer. In addition, Figure 3B also clearly shows that the surface of the polyester amide composite nanofiltration membrane has a morphology similar to particle accumulation, which is obviously different from the traditional polyamide composite nanofiltration membrane.

Figure 4 uses infrared spectroscopy to confirm the formation of ester bonds and amide bonds after the reaction from the perspective of chemical bonds, thereby further confirming the formation of the polyester amide active layer.

Specific embodiment two: This embodiment provides a preparation method of a polyester amide composite nanofiltration membrane with strong chlorine resistance and anti-pollution, and the specific steps are as follows:

1. Preparation of aqueous phase solution: add 1% (w/v) serinol (its structural formula is shown in Figure 1) to pure water, and add 0.2% (w/v) 4-dimethylaminopyridine at the same time as Phase transfer and acylation catalyst, after fully stirring and dissolving, use triethylamine to adjust the pH value of the solution to 11.5;

2. Prepare the organic phase solution: use n-octane as the organic solvent, and add 0.05% (w/v) polyacyl chloride to the organic solvent;

3. With the polysulfone porous ultrafiltration membrane as the supporting layer, first pour the aqueous phase solution on the surface of the supporting layer and soak for 2 minutes, then pour off the aqueous phase solution and remove excess water on the membrane surface, and then pour the organic phase solution on the membrane surface , and react for 50 seconds. After the reaction, use an organic solvent to fully rinse the membrane surface to remove unreacted monomers;

4. Heat-treat the film after rinsing with the organic solvent at 60°C for 15 minutes;

5. Finally, the membrane is fully washed with pure water to obtain a polyester amide composite nanofiltration membrane.

Specific embodiment three: This embodiment provides a preparation method of a polyester amide composite nanofiltration membrane with strong chlorine resistance and anti-pollution, and the specific steps are as follows:

1. Preparation of aqueous phase solution: add 0.5% (w/v) serinol (its structural formula is shown in Figure 1) to pure water, and add 0.05% (w/v) 4-dimethylaminopyridine at the same time as Phase transfer and acylation catalyst, after fully stirring and dissolving, use triethylamine to adjust the pH value of the solution to 11.5;

2. Prepare the organic phase solution: use toluene and cyclohexane as the organic solvent, the volume ratio of the two is 1:1, and add 0.05% (w/v) polyacyl chloride to the organic solvent;

3. With polypropylene porous ultrafiltration membrane as the supporting layer, first pour the aqueous phase solution on the surface of the supporting layer and soak for 4 minutes, then pour off the aqueous phase solution and remove excess water on the membrane surface, and then pour the organic phase solution on the membrane surface , and react for 70 seconds. After the reaction, use an organic solvent to fully rinse the membrane surface to remove unreacted monomers;

4. Heat the film after washing with organic solvent at 70°C for 15 minutes;

5. Finally, the membrane is fully washed with pure water to obtain a polyester amide composite nanofiltration membrane.

Specific embodiment four: This embodiment provides a preparation method of a polyester amide composite nanofiltration membrane with strong chlorine resistance and anti-pollution, and the specific steps are as follows:

1. Preparation of aqueous phase solution: add 1.5% (w/v) serinol (its structural formula is shown in Figure 1) to pure water, and add 0.15% (w/v) 4-dimethylaminopyridine at the same time as Phase transfer and acylation catalyst, after fully stirring and dissolving, use triethylamine to adjust the pH value of the solution to 11.5;

2. Prepare the organic phase solution: use n-octane as the organic solvent, and add 0.07% (w/v) polyacyl chloride to the organic solvent;

3. With the sulfonated polyethersulfone porous ultrafiltration membrane as the supporting layer, first pour the aqueous phase solution on the surface of the supporting layer and soak for 3 minutes, then pour off the aqueous phase solution and remove excess water on the membrane surface, and then pour the organic phase solution Facing the membrane surface and reacting for 60 seconds, after the reaction, use an organic solvent to fully rinse the membrane surface to remove unreacted monomers;

4. Heat-treat the film after washing with organic solvent at 80°C for 15 minutes;

5. Finally, the membrane is fully washed with pure water to obtain a polyester amide composite nanofiltration membrane.

Claims (5)

1. a preparation method of chlorine-resistant strong and anti-pollution polyester amide composite nanofiltration membrane, is characterized in that described method step is as follows: 1. Preparation of aqueous phase solution: add 0.5~5% (w/v) serinol to pure water, and add 0.05~0.5% (w/v) 4-dimethylaminopyridine at the same time, stir well and dissolve Adjust the pH value of the solution to 11.3~12.0; 2. Prepare the organic phase solution: add 0.01~0.5% (w/v) polyacyl chloride to the organic solvent; 3. First, pour the aqueous phase solution onto the surface of the support layer and soak for 1-10 minutes, then pour off the aqueous phase solution and remove excess water on the membrane surface, then pour the organic phase solution onto the membrane surface, and react for 10-120 seconds. After the end, fully rinse the membrane surface with an organic solvent; 4. Carry out heat treatment to the film after washing with organic solvent; 5. Finally, the heat-treated membrane is fully cleaned with pure water to obtain a polyester amide composite nanofiltration membrane. 2. the preparation method of strong chlorine resistance and anti-pollution polyester amide composite nanofiltration membrane according to claim 1, is characterized in that adopting triethylamine to adjust the pH value of solution to 11.3～12.0 in described step 1 . 3. the preparation method of the strong chlorine resistance and anti-pollution polyester amide composite nanofiltration membrane according to claim 1, is characterized in that said organic solvent is normal hexane, hexanaphthene, toluene, normal heptane or normal hexane One or more of octane. 4. the preparation method of the strong chlorine resistance and anti-pollution polyester amide composite nanofiltration membrane according to claim 1 is characterized in that the support layer is polysulfone, polyethersulfone, sulfonated polyethersulfone or polysulfone Propylene porous ultrafiltration membrane. 5. The preparation method of the strong chlorine resistance and anti-pollution polyester amide composite nanofiltration membrane according to claim 1, characterized in that the heat treatment temperature is 20-80° C., and the time is 5-20 minutes.