Preparation method of anti-pollution reverse osmosis concentrated water flow channel cloth

Abstract

The application provides a preparation method of an anti-pollution reverse osmosis concentrated water flow channel cloth, which is characterized in that a low surface energy coating is coated on the reverse osmosis concentrated water flow channel cloth, so that the surface has anti-adhesion properties, the enrichment of pollutants is reduced, the flow channel is not easy to be blocked, the pressure drop of the flow channel is reduced, and the anti-pollution property of various pollutants is improved, meanwhile, the flow channel cloth is easy to clean and the cleaning recovery is improved; by adding two different additives and controlling the particle size through material ratio, an ordered micro-nano structure is formed, water flow turbulence can be effectively increased, concentration polarization can be slowed down, mass transfer efficiency can be improved, and component performance can be improved; through carboxylation modification of titanium dioxide, the carboxyl groups on the surface of the titanium dioxide react with the hydroxyl groups on the surface of the silicon dioxide and the PDMS, a network structure with the silicon dioxide and the titanium dioxide as double crosslinking points is formed, the network structure can be stable and firm in a high shear force environment in the reverse osmosis membrane, and a long-acting anti-pollution effect is achieved.

Description

Technical Field

[0001] This invention relates to the field of reverse osmosis membrane technology, and specifically to a method for preparing an anti-fouling reverse osmosis concentrate flow channel cloth. Background Technology

[0002] Reverse osmosis membranes are widely used in domestic and international markets as an important means of wastewater purification and water resource recycling. However, membrane fouling leads to deterioration of effluent quality, shortened lifespan, and increased operating costs, hindering its further development. The concentrate flow channel fabric, as a crucial component of the reverse osmosis membrane, provides a flow path for both feed water and concentrate, mitigating the accumulation of pollutants on the concentrate side of the membrane. Therefore, designing a high-performance concentrate flow channel fabric plays a vital role in the antifouling performance of the reverse osmosis membrane.

[0003] Existing research mainly focuses on optimizing the thickness, cross-sectional shape, and inlet angle of concentrate flow channel fabrics, with limited attention to material modification. Even when modifications are addressed, they are often limited to single-type fouling caused by scaling, and are ineffective against complex fouling resulting from the coexistence of multiple contaminants. Therefore, how to modify concentrate flow channel fabrics and design high-performance concentrate flow channel fabrics is a pressing issue that needs to be addressed. Summary of the Invention

[0004] The present invention aims to provide a method for preparing anti-fouling reverse osmosis concentrate flow channel cloth to solve the above problems.

[0005] The technical solution of this invention is:

[0006] A method for preparing an anti-fouling reverse osmosis concentrate flow channel cloth includes the following steps:

[0007] Step S1: Mix tetrahydrofuran (THF), deionized water and isopropanol in a certain proportion and stir until homogeneous;

[0008] Step S2: Add hydrochloric acid to adjust the pH of the solution;

[0009] Step S3: After stirring, tetraethyl orthosilicate (TEOS) and polydimethylsiloxane (PDMS) are simultaneously added to the mixed solution to form a sol;

[0010] Step S4: Stir the formed sol at a certain temperature to obtain a PDMS-SiO2 dispersion;

[0011] Step S5: Add carboxylated TiO2 and stir vigorously to obtain a TiO2 mixed solution;

[0012] Step S6: Spray the mixed solution onto the concentrate flow channel cloth using a spray gun, and heat it at a certain temperature to obtain the modified concentrate flow channel cloth.

[0013] Preferably, in step S5, the preparation of carboxylated TiO2 specifically includes:

[0014] Step S51: Add tetrabutyl titanate to pure water at a volume ratio of 2:3, stir until homogeneous, and obtain a clear solution A.

[0015] Step S52: Prepare an ethanol solution of a certain mass concentration. Add solution A slowly dropwise to the ethanol solution while stirring. After the addition is complete, stir vigorously to form a white gel.

[0016] Step S53: After aging the gel for a period of time, wash it with deionized water, and then dry and grind it in a vacuum drying oven at a certain temperature to obtain TiO2 powder;

[0017] Step S54: Weigh a certain amount of TiO2 powder, add distilled water in a certain proportion, sonicate to form a uniform suspension, then add a certain amount of chloroacetic acid aqueous solution, and heat and stir at a certain temperature.

[0018] Step S55: Wash repeatedly to remove unreacted chloroacetic acid, and dry at a certain temperature to obtain carboxylated TiO2.

[0019] Preferably, in step S1, the reaction temperature is below 80°C, and tetrahydrofuran, deionized water and isopropanol are mixed in a volume ratio of 1:3:4.

[0020] In step S2, adjust pH to 2;

[0021] In step S3, the stirring time is 1 hour, the mass ratio of tetraethyl orthosilicate (TEOS) to tetrahydrofuran (THF) in the mixed solution is 1:1, and the mass ratio of tetraethyl orthosilicate (TEOS) to polydimethylsiloxane (PDMS) is 7:3.

[0022] In step S4, the temperature is 80℃ and the stirring time is 12 hours;

[0023] In step S5, the stirring time is 3 hours;

[0024] In step S6, the reaction temperature is 100℃ and the heating time is 4h.

[0025] Preferably, in step S51, the volume ratio of tetrabutyl titanate to pure water is 2:3;

[0026] In step S52, the mass concentration of the ethanol solution is 90%, and the stirring time is 30 minutes after solution A is added dropwise until the ethanol solution is completely dissolved.

[0027] In step S53, the gel aging time is 24 hours and the temperature of the vacuum drying oven is 70°C.

[0028] In step S54, the ratio of TiO2 powder to distilled water is 1:40, the heating and stirring temperature is 90℃, and the time is 30min;

[0029] In step S55, the drying temperature is 40°C.

[0030] The beneficial effects of this invention are as follows:

[0031] This invention provides a method for preparing an anti-fouling reverse osmosis concentrate flow channel cloth, which can achieve the following effects:

[0032] (1) This invention coats the reverse osmosis concentrate flow channel cloth with a low surface energy coating, which makes the surface have anti-adhesion properties, reduces the accumulation of pollutants, makes the flow channel less prone to blockage, reduces the flow channel pressure drop, and thus improves the anti-fouling properties of various pollutants. At the same time, it is easy to clean and improves the cleaning recovery.

[0033] (2) By adding two different additives, the particle size of the raw materials is controlled by the ratio of the raw materials to form an ordered micro-nano structure, which can effectively increase water flow turbulence, reduce concentration polarization, improve mass transfer efficiency, and improve component performance.

[0034] (3) The present invention modifies titanium dioxide by carboxylation, so that the carboxyl groups on the surface of titanium dioxide react with silicon dioxide and PDMS terminal hydroxyl groups in pairs to form a network structure with silicon dioxide and titanium dioxide as double cross-linking points, so that it can be firmly and stably maintained in the high shear force environment inside the reverse osmosis membrane, achieving a long-term anti-fouling effect. Attached Figure Description

[0035] Figure 1 This is a schematic diagram of an electron microscope image of carboxylated TiO2 microspheres provided in an embodiment of the present invention;

[0036] Figure 2 The present invention provides a comparison of the pre-modified concentrate flow channel fabric and the TiO2 / SiO2 / PDMS modified concentrate flow channel fabric, as well as an enlarged schematic diagram of the TiO2 / SiO2 / PDMS modified concentrate flow channel layout.

[0037] Figure 3 A comparison chart of the decay rates of reverse osmosis membrane elements made by rolling TiO2 / SiO2 / PDMS modified concentrate flow channel cloth and normal concentrate flow channel cloth respectively, and subjected to antifouling tests in the same test device, provided for embodiments of the present invention.

[0038] Figure 4 A comparison chart of desalination attenuation provided for embodiments of the present invention, showing reverse osmosis membrane elements rolled up using TiO2 / SiO2 / PDMS modified concentrate flow channel cloth and normal concentrate flow channel cloth, and subjected to antifouling tests in the same testing apparatus;

[0039] Figure 5A comparison chart of flux recovery rates provided for embodiments of the present invention, showing reverse osmosis membrane elements rolled up using TiO2 / SiO2 / PDMS modified concentrate flow channel cloth and normal concentrate flow channel cloth respectively, and subjected to antifouling tests in the same testing apparatus.

[0040] Figure 6 This is a comparison chart of desalination recovery rates provided in this embodiment of the invention, showing the desalination recovery rates of reverse osmosis membrane elements fabricated using TiO2 / SiO2 / PDMS modified concentrate flow channel fabric and normal concentrate flow channel fabric, respectively, and tested under the same antifouling apparatus. Detailed Implementation

[0041] The present invention will be further described below with reference to the accompanying drawings and specific embodiments, so that those skilled in the art can better understand and implement the present invention. The embodiments of the present invention are not limited thereto.

[0042] Example 1

[0043] like Figure 1 The image shows an electron microscopy schematic of carboxylated TiO2 microspheres with a particle size of approximately 2 micrometers. The preparation process is as follows: 10 mL of tetrabutyl titanate was added to 15 mL of pure water and stirred until homogeneous. A 90% ethanol solution was then slowly added dropwise while stirring. After complete addition, the mixture was vigorously stirred for 30 minutes to form a white gel. The gel was allowed to stand for 24 hours, washed with pure water, and then dried in a vacuum drying oven at 70°C. The gel was then ground to obtain TiO2 powder. 5 g of TiO2 powder was weighed and added to 200 g of pure water. The mixture was sonicated for 20 minutes to form a homogeneous suspension. 5 g of ClCH2COOH aqueous solution was added, and the mixture was heated and stirred at 90°C for 30 minutes. After multiple washings, the mixture was dried at 40°C to obtain carboxylated TiO2.

[0044] like Figure 2The image shows a comparison of the unmodified concentrate flow channel fabric and the TiO2 / SiO2 / PDMS modified concentrate flow channel fabric, as well as a magnified view of the TiO2 / SiO2 / PDMS modified concentrate flow channel layout. In the image, part a represents the unmodified concentrate flow channel fabric, part b represents the TiO2 / SiO2 / PDMS modified concentrate flow channel fabric, and part c represents a partial magnified view of the TiO2 / SiO2 / PDMS modified concentrate flow channel fabric. The magnified view of the TiO2 / SiO2 / PDMS modified concentrate flow channel layout reveals its micro / nano structure. The preparation process of the TiO2 / SiO2 / PDMS modified concentrate flow channel fabric is as follows: 100 mL of tetrahydrofuran, 300 mL of deionized water, and 400 mL of isopropanol were mixed and stirred evenly at 80°C. The pH of the mixed solution was adjusted to 2 using hydrochloric acid. After stirring for 1 hour, 100 mL of TEOS and 40 mL of PDMS were simultaneously added to the mixed solution, and the resulting sol was stirred at 80°C for 12 hours. After adding 3g of carboxylated TiO2, the mixture was stirred vigorously for 3 hours. Then, it was sprayed onto the concentrate flow channel fabric using a spray gun and heated at 100℃ for 4 hours to obtain the TiO2 / SiO2 / PDMS modified concentrate flow channel fabric.

[0045] Example 2

[0046] like Figure 3 and Figure 4 The figure shows the antifouling test results of reverse osmosis membrane elements fabricated using TiO2 / SiO2 / PDMS modified concentrate flow channel fabric and normal concentrate flow channel fabric, respectively, and tested in the same test apparatus. The feed water was simulated polluted water, and its water quality parameters are shown in Table 1. The test pressure was 225 psi, recovery was 15%, and pre-pressurization was performed for 30 min. The flux and desalination were tested and recorded as initial flux and desalination rate. Subsequently, the pressure and reflux ratio were kept constant at 15%, and the operation continued. The flux and desalination rate of the element were tested every 30 min. The flux decay rate was calculated based on the test results. When the element's water flux decreased by 20%, the operation was stopped, and the decay rate was compared.

[0047] Test results show that with an initial flux of 30 LMH, the time required for the flux to decrease by 20% using the TiO2 / SiO2 / PDMS modified concentrate flow channel cloth element is 510 min, while the time required for the flux to decrease by 20% using the unmodified flow channel cloth is 300 min. Furthermore, the desalination decay of the TiO2 / SiO2 / PDMS modified concentrate flow channel cloth rolled element is also slower. The experiment proves that the concentrate flow channel cloth exhibits stronger antifouling performance and has practical application prospects.

[0048] Table 1. Water Quality of Simulated Polluted Water Bodies

[0049]

[0050] Example 3

[0051] like Figure 5 and Figure 6 As shown, reverse osmosis membrane elements were fabricated using TiO2 / SiO2 / PDMS modified concentrate flow channel cloth and normal concentrate flow channel cloth, respectively. Antifouling tests were conducted under the same feed water quality conditions. When the element's water flux decreased by 20%, operation was stopped, and acid-alkali cleaning was performed. After cleaning, the element flux and desalination were tested using a simulated fouled aqueous solution as feed water, under constant pressure and a reflux ratio of 15%. Based on the results, the flux and desalination recovery rate were calculated, and a second cycle of fouling was performed, repeating the cleaning procedure. After five cycles, the reverse osmosis element using the TiO2 / SiO2 / PDMS modified concentrate flow channel cloth achieved 100% flux and desalination recovery rate, while the initial flux using the unmodified flow channel cloth decreased from 30 LMH to 27.8 LMH, and the initial desalination rate decreased from 99.55% to 99.49%. The modified flow channel cloth exhibits superior cleaning recovery performance and has promising prospects for large-scale application.

[0052] Those skilled in the art will understand that the accompanying drawings are merely schematic diagrams of one embodiment, and the processes depicted in the drawings are not necessarily essential for implementing the present invention.

Claims

1. A method for preparing an anti-fouling reverse osmosis concentrate flow channel cloth, characterized in that, Includes the following steps: Step S1: Mix tetrahydrofuran (THF), deionized water and isopropanol in a certain proportion and stir until homogeneous; Step S2: Add hydrochloric acid to adjust the pH of the solution; Step S3: After stirring, tetraethyl orthosilicate (TEOS) and polydimethylsiloxane (PDMS) are simultaneously added to the mixed solution to form a sol; Step S4: Stir the formed sol at a certain temperature to obtain a PDMS-SiO2 dispersion; Step S5: Add carboxylated TiO2 and stir vigorously to obtain a TiO2 / SiO2 / PDMS mixed solution; Step S6: Spray the mixed solution onto the concentrate flow channel cloth using a spray gun, and heat it at a certain temperature to obtain TiO2 / SiO2 / PDMS modified concentrate flow channel cloth.

2. The method for preparing an anti-fouling reverse osmosis concentrate flow channel cloth according to claim 1, characterized in that, in, In step S5, the preparation of carboxylated TiO2 specifically includes: Step S51: Add tetrabutyl titanate to pure water at a volume ratio of 2:3, stir until homogeneous, and obtain a clear solution A. Step S52: Prepare an ethanol solution of a certain mass concentration. Add solution A slowly dropwise to the ethanol solution while stirring. After the addition is complete, stir vigorously to form a white gel. Step S53: After aging the gel for a period of time, wash it with deionized water, and then dry and grind it in a vacuum drying oven at a certain temperature to obtain TiO2 powder; Step S54: Weigh a certain amount of TiO2 powder, add distilled water in a certain proportion, sonicate to form a uniform suspension, then add a certain amount of chloroacetic acid aqueous solution, and heat and stir at a certain temperature. Step S55: Wash repeatedly to remove unreacted chloroacetic acid, and dry at a certain temperature to obtain carboxylated TiO2.

3. The method for preparing an anti-fouling reverse osmosis concentrate flow channel cloth according to claim 1, characterized in that, In step S1, the mixing temperature is below 80°C, and tetrahydrofuran, deionized water and isopropanol are mixed in a volume ratio of 1:3:

4. In step S2, adjust the pH to 2; In step S3, the stirring time is 1 hour, the mass ratio of tetraethyl orthosilicate (TEOS) to tetrahydrofuran (THF) in the mixed solution is 1:1, and the mass ratio of tetraethyl orthosilicate (TEOS) to polydimethylsiloxane (PDMS) is 7:

3. In step S4, the temperature is 80℃ and the stirring time is 12 hours; In step S5, the stirring time is 3 hours; In step S6, the heating temperature is 100℃ and the heating time is 4 hours.

4. The method for preparing an anti-fouling reverse osmosis concentrate flow channel cloth according to claim 2, characterized in that, In step S51, the volume ratio of tetrabutyl titanate to pure water is 2:3; In step S52, the mass concentration of the ethanol solution is 90%, and the stirring time is 30 minutes after solution A is added dropwise until the ethanol solution is completely dissolved. In step S53, the gel aging time is 24 hours and the temperature of the vacuum drying oven is 70°C. In step S54, the ratio of TiO2 powder to distilled water is 1:40, the heating and stirring temperature is 90℃, and the time is 30min; In step S55, the drying temperature is 40°C.

Images