Preparation method of surface-coated titanium dioxide polysulfone ultrafiltration membrane

Abstract

The application discloses a preparation method of a surface-coated titanium dioxide polysulfone modified membrane, and belongs to the technical field of water treatment. The preparation method of the surface-coated titanium dioxide polysulfone ultrafiltration membrane specifically comprises the following steps: (1) dopamine-coated polysulfone flat membrane: dopamine is dissolved in a Tris-HCl buffer solution to obtain a dopamine buffer solution, and polysulfone flat membrane is soaked in the dopamine buffer solution to obtain dopamine-coated flat membrane; (2) TiO2 is dissolved in a methanol solution to obtain TiO2 suspension, and the dopamine-coated flat membrane is soaked in the TiO2 suspension to obtain TiO2 surface-coated flat membrane. The preparation method of the surface-coated titanium dioxide polysulfone flat membrane has simple preparation process and low raw material price. The modified membrane has good water treatment effect, can effectively reduce organic matters in water, can effectively reduce membrane pollution, and can prolong the service life of the membrane.

Description

Technical Field

[0001] This invention relates to the field of advanced municipal wastewater treatment technology, specifically to a method for advanced treatment of secondary biological wastewater effluent from municipal sewage. Background Technology

[0002] my country's rapid economic development has exacerbated the already severe water shortage. The effective utilization of water resources plays a crucial role in my country's economic development. Power plants utilize a significant amount of water, and increasing the wastewater reuse rate can effectively reduce the demand for natural water resources by power plants, while also lowering the pollution load on the ecological environment—an effective measure for ecological protection.

[0003] In recent years, ultrafiltration has been widely used as a highly efficient and low-cost water treatment technology. Ultrafiltration technology has advantages such as no phase change in the process, energy saving and environmental protection, and simple operation. Ultrafiltration membranes can effectively remove large molecular organic matter in surface water, thereby achieving the separation of water from large molecular organic matter and water purification. Polysulfone membranes have advantages such as acid and alkali resistance and excellent film-forming properties, making them an excellent ultrafiltration membrane material. However, polysulfone membranes also have limitations such as poor hydrophilicity and poor fouling resistance. The attraction between the polysulfone membrane surface and water molecules is insufficient, and natural organic matter (NOM) in surface water will adsorb onto the polysulfone membrane surface, forming a filter cake layer and clogging the membrane pores, leading to serious membrane fouling and reducing the purification efficiency of surface water. Therefore, the development of polysulfone membranes with high hydrophilicity and fouling resistance is urgently needed. Summary of the Invention

[0004] The primary objective of this invention is to provide a method for preparing a surface-coated titanium dioxide polysulfone ultrafiltration membrane. The method of this invention uses surface coating technology to fix titanium dioxide on the membrane surface, thereby improving the membrane's antifouling ability and extending its service life.

[0005] A method for preparing a surface-coated titanium dioxide polysulfone ultrafiltration membrane specifically includes the following steps:

[0006] (1) Dopamine-coated flat sheet membrane:

[0007] Prepare an 8-15 mmol / L Tris-HCl buffer solution as a solvent, dissolve 0.5-2 mg / mL of dopamine in the solvent, adjust the pH to 8.0-9.0 to obtain a dopamine buffer solution. Soak the polysulfone sheet membrane in the dopamine buffer solution for 4-18 hours, rinse the sheet membrane with deionized water, and dry it to obtain a dopamine-coated sheet membrane.

[0008] (2) Fixing titanium dioxide:

[0009] 0.05-0.2 mol / L TiO2 powder was mixed with methanol solution and ultrasonically treated for 20-40 min to obtain a uniform TiO2 suspension. The dopamine-modified substrate membrane was immersed in the TiO2 suspension and mechanically vibrated at 100 rpm at room temperature for 4-24 h. The flat sheet membrane was then rinsed with deionized water, dried, and the titanium dioxide-modified flat sheet membrane was obtained.

[0010] The pH value is adjusted in step (1) using sodium hydroxide and hydrochloric acid solutions.

[0011] The hollow fiber membrane rinsed with deionized water in step (1) is preferably rinsed with deionized water three times.

[0012] The drying process described in step (1) is preferably performed in a vacuum drying oven at 40°C.

[0013] As a preferred embodiment, the ultrasound in step (2) is preferably performed under the following conditions: ultrasound at 25°C for 30 minutes.

[0014] In step (2), rinsing the flat sheet membrane with deionized water is preferred to rinse the hollow fiber membrane three times with deionized water.

[0015] The drying process described in step (2) is preferably performed in a vacuum drying oven at 40°C.

[0016] A surface-coated titanium dioxide polysulfone ultrafiltration membrane is obtained by the above preparation method.

[0017] Compared with the prior art, the technical solution of the present invention has the following advantages:

[0018] 1. This invention prepares a hydrophilic antifouling membrane with a surface coated with dopamine and titanium dioxide. By utilizing the strong adsorption of dopamine on the material surface, the membrane surface is coated with a dopamine solution, which allows the membrane surface to adsorb titanium dioxide. Immersion in a titanium dioxide solution further coats the membrane surface with titanium dioxide, giving the membrane hydrophilic and antifouling properties.

[0019] 2. The preparation process in this invention is simple and easy to implement, and is suitable for mass production. Due to the strong adsorption effect of dopamine, the prepared titanium dioxide coating adheres firmly to the membrane surface, and the hydrophilic and antifouling properties of the membrane can be maintained for a long time. Detailed Implementation

[0020] The technical solutions of the present invention will be clearly and completely described below with reference to the embodiments of the present invention. Obviously, the described embodiments are only a part of the embodiments of the present invention, and not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative effort are within the scope of protection of the present invention.

[0021] Example 1

[0022] (1) Dopamine-coated flat sheet membrane:

[0023] Prepare a 15 mmol / L tris-hydroxymethylaminomethane hydrochloride (Tris-HCl) buffer solution as a solvent, dissolve 1 mg / mL of dopamine in the solvent, adjust the pH to 8.5, and obtain a dopamine buffer solution. Soak the polysulfone sheet membrane in the dopamine buffer solution for 12 h, rinse the sheet membrane with deionized water, and dry it to obtain a dopamine-coated sheet membrane.

[0024] (2) Fixing titanium dioxide:

[0025] 0.1 mol / L TiO2 powder was mixed with methanol solution and sonicated for 30 min to obtain a uniform TiO2 suspension. The dopamine-modified substrate membrane was immersed in the TiO2 suspension and mechanically vibrated at 100 rpm for 12 h at room temperature. The flat sheet membrane was then rinsed with deionized water, dried, and the titanium dioxide-modified flat sheet membrane was obtained.

[0026] The hydrophilic antifouling membrane prepared above was compared with the untreated base membrane in terms of hydrophilicity and antifouling performance. The test results showed that, compared with the untreated base membrane, the static contact angle of the hydrophilic antifouling membrane prepared by this method decreased from the initial 84° to 12°, and the pure water flux of the membrane increased from 1587 L / (m²). 3 •h) increased to 2386L / (m 3 (·h), the single-cycle membrane flux increased from 0.83 to 0.95.

[0027] Example 2

[0028] (1) Dopamine-coated flat sheet membrane:

[0029] Prepare a 9 mmol / L tris-hydroxymethylaminomethane hydrochloride (Tris-HCl) buffer solution as a solvent, dissolve 1.5 mg / mL of dopamine in the solvent, adjust the pH to 8.0, and obtain a dopamine buffer solution. Soak the polysulfone sheet membrane in the dopamine buffer solution for 18 h, rinse the sheet membrane with deionized water, and dry it to obtain a dopamine-coated sheet membrane.

[0030] (2) Fixing titanium dioxide:

[0031] 0.2 mol / L TiO2 powder was mixed with methanol solution and sonicated for 20 min to obtain a uniform TiO2 suspension. The dopamine-modified substrate membrane was immersed in the TiO2 suspension and mechanically vibrated at 100 rpm for 8 h at room temperature. The sheet membrane was then rinsed with deionized water, dried, and the titanium dioxide-modified sheet membrane was obtained.

[0032] The hydrophilic antifouling membrane prepared above was compared with the untreated base membrane in terms of hydrophilicity and antifouling performance. The test results showed that, compared with the untreated base membrane, the static contact angle of the hydrophilic antifouling membrane prepared by this method decreased from the initial 84° to 12°, and the pure water flux of the membrane increased from 1587 L / (m²). 3 •h) increased to 2386L / (m 3 (·h), the single-cycle membrane flux increased from 0.83 to 0.95.

[0033] Example 3

[0034] (1) Dopamine-coated flat sheet membrane:

[0035] Prepare a 12 mmol / L tris-hydroxymethylaminomethane hydrochloride (Tris-HCl) buffer solution as a solvent, dissolve 1 mg / mL of dopamine in the solvent, adjust the pH to 9.0, and obtain a dopamine buffer solution. Soak the polysulfone sheet membrane in the dopamine buffer solution for 8 hours, rinse the sheet membrane with deionized water, and dry it to obtain a dopamine-coated sheet membrane.

[0036] (2) Fixing titanium dioxide:

[0037] 0.05 mol / L TiO2 powder was mixed with methanol solution and sonicated for 40 min to obtain a uniform TiO2 suspension. The dopamine-modified substrate membrane was immersed in the TiO2 suspension and mechanically vibrated at 100 rpm for 16 h at room temperature. The flat sheet membrane was then rinsed with deionized water, dried, and the titanium dioxide-modified flat sheet membrane was obtained.

[0038] The hydrophilic antifouling membrane prepared above was compared with the untreated base membrane in terms of hydrophilicity and antifouling performance. The test results showed that, compared with the untreated base membrane, the static contact angle of the hydrophilic antifouling membrane prepared by this method decreased from the initial 84° to 12°, and the pure water flux of the membrane increased from 1587 L / (m²). 3 •h) increased to 2386L / (m 3 (·h), the single-cycle membrane flux increased from 0.83 to 0.95.

[0039] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions, and improvements made within the spirit and principles of the present invention should be included within the protection scope of the present invention.

Claims

1. A method for preparing a surface-coated titanium dioxide polysulfone ultrafiltration membrane, characterized in that, Specifically, the following steps are included: Step 1: Dopamine coating of the flat sheet membrane. Prepare an 8-15 mmol / L tris-hydroxymethylaminomethane hydrochloride (Tris-HCl) buffer solution as a solvent, dissolve 0.5-2 mg / mL of dopamine in the solvent, and adjust the pH to 8.0-9.0 to obtain a dopamine buffer solution. Immerse the polysulfone sheet membrane in the dopamine buffer solution for 4-18 hours, rinse the sheet membrane with deionized water, and dry it to obtain a dopamine-coated sheet membrane. Step 2: Fix titanium dioxide. Mix 0.05-0.2 mol / L TiO2 powder with methanol solution and sonicate for 20-40 min to obtain a uniform TiO2 suspension. Immerse the dopamine-modified substrate membrane in the TiO2 suspension and mechanically vibrate at 100 rpm at room temperature for 4-24 h. Rinse the sheet membrane with deionized water and dry it to obtain the titanium dioxide modified sheet membrane.

2. The method for preparing a surface-coated titanium dioxide polysulfone ultrafiltration membrane according to claim 1, characterized in that: In step 1, the pH value is adjusted using sodium hydroxide and hydrochloric acid solutions.

3. The method for preparing a surface-coated titanium dioxide polysulfone ultrafiltration membrane according to claim 1, characterized in that: In step 1, the flat sheet membrane is rinsed with deionized water three times.

4. The method for preparing a surface-coated titanium dioxide polysulfone ultrafiltration membrane according to claim 1, characterized in that: In step 1, drying is performed in a vacuum drying oven at 40°C.

5. The method for preparing a surface-coated titanium dioxide polysulfone ultrafiltration membrane according to claim 1, characterized in that: In step 2, the ultrasound is performed under the following conditions: ultrasound at 25℃ for 30 minutes.

6. The method for preparing a surface-coated titanium dioxide polysulfone ultrafiltration membrane according to claim 1, characterized in that: In step 2, the plate is rinsed with deionized water, which means rinsing the plate membrane with deionized water 3 times.