A method for preparing a hybrid matrix reverse osmosis membrane using mesoporous silica nanotubes
By introducing mesoporous silica nanotubes, the problem of salt rejection rate decreasing when increasing the flux of reverse osmosis membranes was solved, achieving a balance between high flux and high salt rejection rate, and producing high-performance reverse osmosis membranes.
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Patents(China)
- Current Assignee / Owner
- ZHEJIANG UNIV OF TECH
- Filing Date
- 2023-11-01
- Publication Date
- 2026-07-21
AI Technical Summary
While increasing the flux of existing reverse osmosis membranes, it is common to see a decrease in salt rejection rate, making it difficult to increase the water flux of the membrane while maintaining high desalination performance.
Mesoporous silica nanotubes were used as an additive to prepare a hybrid matrix reverse osmosis membrane via interfacial polymerization. The mesoporous silica nanotubes provided more water inlet channels, thereby enhancing water transport efficiency.
While maintaining a high salt rejection rate, the water flux of the reverse osmosis membrane was significantly improved, achieving a high-performance membrane material.
Smart Images
Figure HDA0004525749360000011
Abstract
Description
Technical Field
[0001] This invention relates to the field of water treatment membrane technology, and more specifically to a method for preparing a mixed matrix reverse osmosis membrane using mesoporous silica nanotubes. Background Technology
[0002] In recent years, with the continuous growth of the world's population and the ongoing development of industrialization, the problem of freshwater scarcity has become increasingly serious. Saltwater from the ocean accounts for more than 97% of the water on the Earth's surface, forming a vast reservoir that should be effectively utilized to alleviate the current global water shortage. Seawater desalination refers to the removal of salt and other minerals from seawater or brackish water to obtain freshwater resources needed for human production and daily life. Among existing development technologies, reverse osmosis (RO) is a key technology for producing freshwater from seawater / brackish water, offering advantages such as simple operation, low energy consumption, and small footprint.
[0003] The core of reverse osmosis technology is the reverse osmosis membrane. Aromatic polyamide reverse osmosis composite membranes have become the mainstream product in the market due to their excellent selective permeability and operational stability. The traditional production process of polyamide reverse osmosis membranes mainly employs interfacial polymerization technology, which involves the polymerization reaction of m-phenylenediamine and trimesoyl chloride to form a dense polyamide membrane on a carrier. However, there is often a trade-off between membrane flux and desalination performance. Therefore, improving the performance of reverse osmosis membranes has always been a hot topic. More and more researchers are attempting to introduce nanomaterials into the interfacial polymerization process to modify thin-film composite polyamide membranes to improve membrane performance. For example, carbon nanotubes are added to the aqueous or oil phase solution used to synthesize polyamide membranes to prepare carbon nanotube-containing reverse osmosis composite membranes. The unique microporous structure and excellent water channeling of carbon nanotubes enhance membrane channels. However, because it is difficult to make the nanotube channels perpendicular to the membrane surface, the water transport path length increases, which to some extent limits further improvement in membrane performance.
[0004] CN111001309A discloses a method for preparing a mixed-matrix reverse osmosis membrane using amino-modified mesoporous silica nanospheres. The method uses a polysulfone-supported membrane as the base membrane, m-phenylenediamine as the aqueous monomer, trimesoyl chloride as the oil-phase monomer, amino-modified mesoporous silica nanospheres as the oil-phase additive, and n-heptane as the oil-phase solvent, employing an interfacial polymerization method to prepare the mixed-matrix reverse osmosis membrane. The patent embodiment shows that the reverse osmosis membrane with unmodified mesoporous silica nanospheres as an additive achieved a membrane flux and rejection rate of 61 L·m⁻¹ in a test filtering a 2000 ppm sodium chloride aqueous solution at 15.5 bar and 25°C. -2 ·h -1 And 98.19%, compared to the unadded reverse osmosis membrane (membrane flux and rejection rate were 33 L·m⁻¹).-2 ·h -1 The flux was significantly increased (99.20%), but the salt rejection rate was significantly reduced. Summary of the Invention
[0005] The purpose of this invention is to provide a method for preparing a mixed matrix reverse osmosis membrane using mesoporous silica nanotubes, which significantly improves flux while maintaining a high rejection rate.
[0006] The present invention is achieved through the following technical solution.
[0007] A method for preparing a hybrid matrix reverse osmosis membrane using mesoporous silica nanotubes is implemented according to the following steps:
[0008] 1) Solid silicon rods were obtained by using Pluronic F127 block copolymer and hexadecyltrimethylammonium bromide in the presence of tetraethyl orthosilicate. Then, hydrochloric acid was used to remove the surfactant to further obtain mesoporous materials. Finally, mesoporous silicon nanotubes were obtained by etching with polyethyleneimine.
[0009] 2) Then, the synthesized mesoporous silica nanotubes are added to an aqueous solution containing m-phenylenediamine and dispersed evenly to obtain an aqueous solution with a mesoporous silica nanotube content of 0.005% w / v to 0.04% w / v.
[0010] 3) The aqueous solution obtained in step 2) and the oil solution of trimesoyl chloride are used to form a polyamide layer on the support layer by interfacial polymerization to obtain a mixed matrix reverse osmosis membrane.
[0011] The specific operation of step 1) of this invention can be carried out with reference to the method reported in existing literature (such as Liang You, et al. When Mesoporous Silica Meets the Alkaline Polyelectrolyte: A Controllable Synthesis of Functional and Hollow Nanostructures with a Porous Shell. Chem. Eur. J. 2013, 19, 2142-2149). Specifically, step 1) of this invention is carried out according to the following steps: Pluronic F127 block copolymer and hexadecyltrimethylammonium bromide are added to ammonia and water, dissolved and transparent, and then tetraethyl orthosilicate is added to initiate the reaction at room temperature for 2 hours. After thorough washing with water by centrifugation, a solid silicon rod is obtained. Then, the silicon rod is added to 38wt%-40wt% hydrochloric acid and ethanol, refluxed at 75°C for 1 hour, and thoroughly washed with water by centrifugation to obtain a silicon dispersion. Finally, the silicon dispersion is added to a prepared aqueous solution of polyethyleneimine, refluxed at 90°C for 2 hours, and thoroughly washed with water by centrifugation to obtain mesoporous silicon nanotubes. The feeding ratio of Pluronic F127 block copolymer, hexadecyltrimethylammonium bromide, tetraethyl orthosilicate, and polyethyleneimine is 0.05-1g:0.1-1.5g:0.1-1.5mL:1-3mg. Preferably, the feed ratio of the Pluronic F127 block copolymer to cetyltrimethylammonium bromide, tetraethyl orthosilicate, and polyethyleneimine is 0.246 g: 0.6 g: 0.6 mL: 2 mg.
[0012] Preferably, the aqueous solution in step 2) is an aqueous solution containing 0.5% w / v-3% w / v triethylamine, 1% w / v-4% w / v camphorsulfonic acid, 1% w / v-3% w / v m-phenylenediamine, and 0.005% w / v-0.04% w / v mesoporous nanotubes. More preferably, in step 2), the aqueous solution contains 0.02% w / v mesoporous silica nanotubes. Even more preferably, the aqueous solution contains 1.1% w / v triethylamine, 2.6% w / v camphorsulfonic acid, and 2% w / v m-phenylenediamine.
[0013] Preferably, in step 3), the pyromellitic chloride oil phase solution is a pyromellitic chloride n-heptane solution with a concentration of 0.01% w / v to 0.3% w / v, and more preferably a pyromellitic chloride n-heptane solution with a concentration of 0.1% w / v.
[0014] Step 3) of the present invention can be carried out using conventional interfacial polymerization: the support membrane is immersed in an aqueous solution for a certain time (e.g., 30-60s), and after the support layer is fully immersed, the support membrane is dried and then an oil phase solution is poured on it and left to stand for a certain time (e.g., 30-60s) to initiate an interfacial polymerization reaction to form a polyamide layer.
[0015] As a preferred option, the interface aggregation time is 30 seconds.
[0016] In this invention, the supporting membrane may be a polysulfone supporting membrane.
[0017] This invention innovatively applies mesoporous silica nanotubes to reverse osmosis membrane materials to obtain reverse osmosis membranes with high water flux and high selectivity. The polyethyleneimine remaining during the preparation of the mesoporous silica nanotubes can appropriately increase the compatibility between the mesoporous silica nanotubes and polyamide, ensuring a high desalination rate of the reverse osmosis membrane. The inherent channels within the nanotubes provide additional transport channels, improving the permeability of the reverse osmosis membrane. During nanotube preparation, hydrochloric acid is used to remove surfactants, transforming the original solid silica rods into mesoporous structures. The surface mesopores provide more inlets, facilitating rapid water transport, thereby producing the high-performance reverse osmosis membrane described in this specification. Compared to traditional reverse osmosis membranes prepared using nanotubes with non-porous surfaces, such as carbon nanotubes, the mixed-matrix reverse osmosis membrane prepared using mesoporous silica nanotubes provides more inlets, accelerating the rapid water transport along the nanotubes. This results in a modified reverse osmosis membrane that maintains high selectivity while exhibiting higher permeability.
[0018] Compared with the prior art, the beneficial effects of the present invention are as follows:
[0019] (1) The present invention has the advantages of low operation difficulty, low production cost and low environmental harm.
[0020] (2) The mesoporous silicon nanotubes synthesized in this invention have more inlets, which can accelerate the water transport process in the polyamide membrane.
[0021] (3) While significantly improving the water flux of the reverse osmosis membrane, the present invention also maintains the salt rejection rate of the membrane at a high level, so that the prepared reverse osmosis membrane has both high flux and high salt rejection rate. Attached Figure Description
[0022] Figure 1 Transmission electron microscope image of the mesoporous silicon nanotube material prepared in Example 1. Detailed Implementation
[0023] The technical solution of the present invention will be further described below through specific embodiments, but the scope of protection of the present invention is not limited thereto.
[0024] Example 1
[0025] 0.246 g of Pluronic F127 block copolymer and 0.6 g of cetyltrimethylammonium bromide were added to 2 ml of 28 wt%-30 wt% ammonia solution and 58 ml of water. After dissolving and becoming transparent, 0.6 ml of tetraethyl orthosilicate was added to initiate the reaction at room temperature for 2 h. The mixture was then washed three times by centrifugation with water to obtain a solid silicon rod. The solid silicon rod was then added to 2 ml of 38 wt%-40 wt% hydrochloric acid and 40 ml of ethanol, refluxed at 75 °C for 1 h, and washed three times by centrifugation with water to obtain 10 mL of a silicon aqueous dispersion. Finally, the silicon dispersion was added to 40 ml of a prepared 0.05 mg / mL solution. -1 The product was prepared by refluxing a polyethyleneimine aqueous solution at 90°C for 2 hours, followed by centrifugation and washing three times to obtain mesoporous silica nanotubes. These mesoporous silica nanotubes were used in subsequent examples.
[0026] Example 2
[0027] The area is 100cm 2 A 10cm × 10cm polysulfone-supported membrane was immersed in an aqueous solution containing 1.1% w / v triethylamine, 2.6% w / v camphor sulfonic acid, 2% w / v m-phenylenediamine, and 0.005% w / v mesoporous silica nanotubes for 30 seconds to ensure thorough wetting. The solution was then discarded. Next, after ensuring no visible liquid remained on the membrane surface, the membrane surface was immersed in a 0.10% w / v solution of trimesoyl chloride in n-heptane to initiate interfacial polymerization for 30 seconds. Finally, the membrane was heat-treated at 80°C for 5 minutes to obtain an aromatic polyamide composite reverse osmosis membrane, which was immediately and thoroughly rinsed with deionized water.
[0028] The composite reverse osmosis membrane was tested at 15.5 bar and 25°C, filtering a 2000 ppm sodium chloride aqueous solution, and the flux and rejection rate were found to be 38 L·m⁻¹. -2 ·h -1 And 99.68%.
[0029] Example 3
[0030] The area is 100cm 2 A 10cm × 10cm polysulfone-supported membrane was immersed in an aqueous solution containing 1.1% w / v triethylamine, 2.6% w / v camphor sulfonic acid, 2% w / v m-phenylenediamine, and 0.02% w / v mesoporous silica nanotubes for 30 seconds to ensure thorough wetting. The solution was then discarded. Next, after ensuring no visible liquid remained on the membrane surface, the membrane surface was immersed in a 0.10% w / v solution of trimesoyl chloride in n-heptane to initiate interfacial polymerization for 30 seconds. Finally, the membrane was heat-treated at 80°C for 5 minutes to obtain an aromatic polyamide composite reverse osmosis membrane, which was immediately and thoroughly rinsed with deionized water.
[0031] The composite reverse osmosis membrane was tested at 15.5 bar and 25°C, filtering a 2000 ppm sodium chloride aqueous solution, and the flux and rejection rate were found to be 65 L·m⁻¹. -2 ·h -1 And 99.02%.
[0032] Example 4
[0033] The area is 100cm 2 A 10cm × 10cm polysulfone-supported membrane was immersed in an aqueous solution containing 1.1% w / v triethylamine, 2.6% w / v camphor sulfonic acid, 2% w / v m-phenylenediamine, and 0.04% w / v mesoporous silica nanotubes for 30 seconds to ensure thorough wetting. The solution was then discarded. Next, after ensuring no visible liquid remained on the membrane surface, the membrane surface was immersed in a 0.10% w / v solution of trimesoyl chloride in n-heptane to initiate interfacial polymerization for 30 seconds. Finally, the membrane was heat-treated at 80°C for 5 minutes to obtain an aromatic polyamide composite reverse osmosis membrane, which was immediately and thoroughly rinsed with deionized water.
[0034] The composite reverse osmosis membrane was tested at 15.5 bar and 25°C, filtering a 2000 ppm sodium chloride aqueous solution, and the flux and rejection rate were found to be 44 L·m⁻¹. -2 ·h -1 And 99.69%.
[0035] Comparative Example 1
[0036] The area is 100cm 2 A 10cm × 10cm polysulfone-supported membrane was immersed in an aqueous solution containing 1.1% w / v triethylamine, 2.6% w / v camphor sulfonic acid, and 2% w / v m-phenylenediamine for 30 seconds to ensure thorough wetting. The solution was then discarded. Next, after ensuring no visible liquid remained on the membrane surface, the membrane surface was immersed in a 0.10% w / v heptane oil solution of trimesoyl chloride to initiate interfacial polymerization for 30 seconds. The membrane was then heat-treated at 80°C for 5 minutes to obtain an aromatic polyamide composite reverse osmosis membrane, which was immediately and thoroughly rinsed with deionized water.
[0037] The composite reverse osmosis membrane was tested at 15.5 bar and 25°C, filtering a 2000 ppm sodium chloride aqueous solution, and the flux and rejection rate were found to be 35 L·m⁻¹. -2 ·h -1 And 99.32%.
[0038] The optimal embodiment (Example 3) of the present invention was compared with the comparative example, and the results are shown in the table. In the table, membrane 1 and membrane 2 represent the reverse osmosis membrane prepared in Comparative Example 1 without the use of mesoporous silica nanotube material and the reverse osmosis membrane prepared in Example 3 using mesoporous silica nanotube material, respectively. As can be seen from the table, the reverse osmosis membrane prepared using mesoporous silica nanotube material can maintain a high salt rejection rate (99.02%) while increasing the membrane flux from 35 L·m -2 ·h -1 Significantly increased to 65 L·m -2 ·h -1 (85.71% improvement). Thanks to the innovative process of using mesoporous silica nanotubes, the surface mesopores provide more inlets for water, thereby increasing the permeability of the prepared polyamide membrane. In summary, using mesoporous silica nanotubes to prepare hybrid matrix reverse osmosis membranes is an effective method to significantly improve membrane flux while maintaining a high salt rejection rate.
[0039] membrane Flux (L-m -2 ·h -1 )]]> Sodium chloride retention rate (%) 1 35 99.32 2 65 99.02
[0040] This invention discloses a method for preparing a hybrid matrix reverse osmosis membrane using mesoporous silica nanotubes to improve reverse osmosis membrane flux and retention. Those skilled in the art can implement this method by appropriately modifying conditions and procedures, based on the content of this document. Although the method and preparation technique of this invention have been described through preferred embodiments, those skilled in the art can obviously modify or recombine the methods and techniques described herein without departing from the content, spirit, and scope of this invention to achieve the final preparation technique. It is particularly important to note that all similar substitutions and modifications are obvious to those skilled in the art and are considered to be included within the spirit, scope, and content of this invention.
Claims
1. A method for preparing a hybrid matrix reverse osmosis membrane using mesoporous silica nanotubes, characterized in that: The method is implemented according to the following steps: 1) Solid silicon rods were obtained by using Pluronic F127 block copolymer and hexadecyltrimethylammonium bromide in the presence of tetraethyl orthosilicate. Then, hydrochloric acid was used to remove the surfactant to further obtain mesoporous materials. Finally, mesoporous silicon nanotubes were obtained by etching with polyethyleneimine. 2) Then, the synthesized mesoporous silica nanotubes are added to an aqueous solution containing m-phenylenediamine and dispersed evenly to obtain an aqueous solution with a mesoporous silica nanotube content of 0.005% w / v to 0.04% w / v. 3) The aqueous solution obtained in step 2) and the oil solution of trimesoyl chloride are used to form a polyamide layer on the support layer by interfacial polymerization to obtain a mixed matrix reverse osmosis membrane.
2. The method as described in claim 1, characterized in that: The aqueous solution described in step 2) is an aqueous solution containing 0.5% w / v-3% w / v triethylamine, 1% w / v-4% w / v camphor sulfonic acid, 1% w / v-3% w / v m-phenylenediamine and 0.005% w / v-0.04% w / v mesoporous nanotubes.
3. The method as described in claim 1 or 2, characterized in that: In step 2), the content of mesoporous silicon nanotubes in the aqueous solution is 0.02% w / v.
4. The method as described in claim 1 or 2, characterized in that: The aqueous solution contains 1.1% w / v triethylamine, 2.6% w / v camphor sulfonic acid and 2% w / v m-phenylenediamine.
5. The method as described in claim 1, characterized in that: In step 3), the pyromellitic chloride oil phase solution is a n-heptane solution of pyromellitic chloride with a concentration of 0.01% w / v to 0.3% w / v.
6. The method as described in claim 1, characterized in that: In step 3), the pyromellitic chloride oil phase solution is a 0.1% w / v pyromellitic chloride n-heptane solution.
7. The method as described in claim 1, characterized in that: Step 3) The specific operation is as follows: Immerse the support membrane in the aqueous solution for 30-60 seconds. After the support layer is fully wetted, blow dry the support membrane and then pour the oil solution on it. Let it stand for 30-60 seconds to initiate the interfacial polymerization reaction and form a polyamide layer.
8. The method as described in claim 7, characterized in that: The interface aggregation time is 30 seconds.
9. The method as described in claim 1, characterized in that: The support layer is a polysulfone support film.