Preparation method of novel nano-powder modified ceramic composite nanofiltration membrane

Abstract

The invention relates to the technical field of preparation of separation membranes, in particular to a preparation method of a novel nano-powder modified ceramic composite nanofiltration membrane, which prepares a composite ceramic membrane with special surface wettability by covalently modifying amino-functionalized silicon carbide (NH2-SiO2atSiC) on an alumina carrier as an active layer. The problems of complex preparation process, high preparation cost and the like of the current ceramic-based nanofiltration membrane are solved. Meanwhile, SiC is properly functionalized and is covalently crosslinked to serve as the active layer on the ceramic microfiltration carrier, so that high stability is provided for the obtained composite ceramic membrane, and chemical components of the active layer can be freely changed.

Description

Technical Field

[0001] The present invention relates to the technical field of separation membrane preparation, in particular to a method for preparing a novel nano-powder-modified ceramic composite nanofiltration membrane. Background Art

[0002] Membrane separation, as an important supporting technology for separation, purification and concentration, is widely used in chemical production, biopharmaceuticals, food processing, wastewater treatment and resource reuse, deep purification of drinking water and other fields.

[0003] Research on nanofiltration membranes in recent years has shown that there have been more studies on pure inorganic nanofiltration membranes and pure organic nanofiltration membranes, but both have some problems in practical application. The currently widely used organic nanofiltration membranes have many advantages, such as high air permeability, low density, good film-forming properties, low cost, and good flexibility. However, due to their poor resistance to high temperatures, organic solvents, and acids and alkalis, they have lost their value in many fields. Compared with polymer organic membranes, ceramic membranes, as an advanced separation membrane material, have the characteristics of high mechanical strength, acid and alkali resistance, high temperature resistance, resistance to various organic solvents and oxidants, good anti-pollution, high filtration accuracy, and long service life. The ceramic membranes prepared by the current general technical level are mainly reflected in the microfiltration and ultrafiltration levels. The preparation of nanofiltration-level ceramic membranes is relatively complex. The layer-by-layer coating method of powder particles requires extremely fine powders, solves the problem of powder agglomeration, and requires multiple firings, resulting in high membrane pore size precision. The sol-gel method is a common technology for preparing nanofiltration ceramic membranes. Although it can achieve pore sizes below 2nm, it also faces the problem of matching the sol properties with the ceramic base membrane, and still requires layer-by-layer coating until the colloid stops leaking. Therefore, both methods have the problems of complex preparation processes and high production costs.

[0004] Given the huge market potential for treating oily wastewater, a ceramic membrane with exceptional surface wettability was prepared by covalently modifying amino-functionalized silicon carbide (NH2-SiO2@SiC) on an alumina support as an active layer. NH2-SiO2@SiC was synthesized by growing a layer of silicon dioxide (SiO2) on silicon carbide (SiC). SiO2@SiC was then functionalized with amino groups (-NH2) using 3-aminopropyltriethoxysilane (APTES) to produce NH2-SiO2@SiC. The amino-functionalized NH2-SiO2@SiC was synthesized by an IP reaction with TPC and deposited on an alumina support, resulting in the preparation of a (NH2-SiO2@SiC / PA@Al2O3) ceramic membrane for the separation of oil-in-water (O / W) emulsions.

[0005] In summary, the present invention solves the existing problems by designing a novel method for preparing a nanopowder-modified ceramic composite nanofiltration membrane. Summary of the Invention

[0006] The purpose of the present invention is to provide a method for preparing a novel nanopowder-modified ceramic composite nanofiltration membrane to solve the problems raised in the above background technology.

[0007] To achieve the above object, the present invention provides the following technical solutions:

[0008] A method for preparing a novel nanopowder-modified ceramic composite nanofiltration membrane, the specific steps are as follows:

[0009] Step (1): Weigh a certain amount of silicon carbide powder and place it in a crucible. Then, calcine it at a high temperature in a muffle furnace under air atmosphere. After the calcination reaction is completed, SiO2@SiC powder is obtained.

[0010] Step (2): a certain mass of SiO2@SiC is dispersed in a round-bottom flask with a magnetic stirrer containing ethanol, and a certain volume of silane coupling agent KH-550 is added to the stirred solution to react, and amino-functionalized NH2-SiO2@SiC nanopowder is obtained by silane coupling treatment;

[0011] Step (3): The alumina membrane is installed in a homemade coating device, a certain concentration of NH2-SiO2@SiC powder is added to an aqueous solution and ultrasonically dispersed, and then used as a feed through a ceramic carrier at a certain constant pressure, and compressed air is blown to the inner surface of the membrane tube until there are no water droplets on the surface, and then the membrane tube is vertically and quickly immersed in the organic phase solution for a certain contact time; after being taken out, it is washed with clean n-hexane to remove excess unreacted monomers, and then the membrane is placed in an oven for curing for a period of time, thereby obtaining a ceramic membrane named SiO2@SiC / PA@Al2O3;

[0012] Step (4): filtering a certain concentration of oil-in-water emulsion under a certain pressure in a dead-end filtration mode to test the performance of the ceramic nanofiltration membrane;

[0013] The ceramic membrane in step (3) is first immersed in an ethanol solution for ultrasonic cleaning to remove impurities on its surface and in its pores, and then immersed in an aqueous solution of sodium dodecyl sulfate (SDS) to increase the wettability of the ceramic membrane substrate;

[0014] The aqueous phase solution in step (3) is a piperazine aqueous solution, and the organic phase solution is a terephthaloyl chloride n-hexane solution.

[0015] As a preferred embodiment of the present invention, the calcination procedure in step (1) is to heat the mixture to 700° C. at 4° C. / min, keep the temperature for 2 h, and cool the mixture naturally to room temperature.

[0016] As a preferred embodiment of the present invention, the time for the amino functionalization treatment in step (2) is 24 hours.

[0017] As a preferred solution of the present invention, the concentration of NH2-SiO2@SiC nanopowder in step (3) is 50, 100 and 200 mg / 100 ml.

[0018] As a preferred solution of the present invention, the concentration of the SDS aqueous solution in step (3) is 0.5% (w / v), and the pore size of the ceramic membrane is in the range of 0.2-0.8 μm.

[0019] As a preferred solution of the present invention, the concentration of the oil-in-water emulsion in step (4) is 67.5-250ppm, and the filtration pressure is 0.5-2bar.

[0020] As a preferred embodiment of the present invention, the concentration of the piperazine aqueous solution is 2% (w / v), and the concentration of the terephthaloyl chloride n-hexane solution is 0.15% (w / v).

[0021] Compared with the prior art, the present invention has the following beneficial effects:

[0022] 1. The present invention loads functionalized nanopowders on an inorganic ceramic membrane and prepares a novel composite ceramic nanofiltration membrane through interfacial polymerization.

[0023] 2. The present invention loads functionalized nanopowders on an inorganic ceramic membrane and prepares a novel composite ceramic nanofiltration membrane through interfacial polymerization. Under test conditions of room temperature and 1 bar, the ceramic nanofiltration membrane with a nanopowder loading of 100 mg / 100 mL has a maximum permeation flux of 77.74 LMH and a high retention rate (99.88%) for a 200 ppm concentration of oil-in-water emulsion.

[0024] 3. The obvious advantages of using ceramic membranes in oil-in-water emulsion separation are high thermal and chemical stability, easy toughness, high hydrophilicity, relatively low operating pressure, and higher oil-in-water emulsion separation efficiency.

[0025] 4. Depositing functionalized nanopowders on ceramic membranes to achieve underwater superoleophobicity is an excellent choice for separating oil-in-water emulsions, allowing water to pass through while preventing oil from contacting the membrane surface, minimizing contamination. BRIEF DESCRIPTION OF THE DRAWINGS

[0026] Figure 1 Schematic diagrams of the ceramic membrane surfaces at two different magnifications: Al2O3 ceramic porous carrier and SiO2@SiC / PA@Al2O3. DETAILED DESCRIPTION

[0027] The following will clearly and completely describe the technical solutions in the embodiments of the present invention in conjunction with the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, rather than all the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making creative work are within the scope of protection of the present invention.

[0028] For examples, see Figure 1 , the present invention provides a technical solution:

[0029] A method for preparing a novel nanopowder-modified ceramic composite nanofiltration membrane, the specific steps are as follows:

[0030] Step (1): Weigh a certain amount of silicon carbide powder and place it in a crucible. Then, calcine it at a high temperature in a muffle furnace under air atmosphere. After the calcination reaction is completed, SiO2@SiC powder is obtained.

[0031] Step (2): a certain mass of SiO2@SiC is dispersed in a round-bottom flask with a magnetic stirrer containing ethanol, and a certain volume of silane coupling agent KH-550 is added to the stirred solution to react, and amino-functionalized NH2-SiO2@SiC nanopowder is obtained by silane coupling treatment;

[0032] Step (3): The alumina membrane is installed in a homemade coating device, a certain concentration of NH2-SiO2@SiC powder is added to an aqueous solution and ultrasonically dispersed, and then used as a feed through a ceramic carrier at a certain constant pressure, and compressed air is blown to the inner surface of the membrane tube until there are no water droplets on the surface, and then the membrane tube is vertically and quickly immersed in the organic phase solution for a certain contact time; after being taken out, it is washed with clean n-hexane to remove excess unreacted monomers, and then the membrane is placed in an oven for curing for a period of time, thereby obtaining a ceramic membrane named SiO2@SiC / PA@Al2O3;

[0033] Step (4): filtering a certain concentration of oil-in-water emulsion under a certain pressure in a dead-end filtration mode to test the performance of the ceramic nanofiltration membrane;

[0034] The ceramic membrane in step (3) is first immersed in an ethanol solution for ultrasonic cleaning to remove impurities on its surface and in its pores, and then immersed in an aqueous solution of sodium dodecyl sulfate (SDS) to increase the wettability of the ceramic membrane substrate;

[0035] The aqueous phase solution in step (3) is a piperazine aqueous solution, and the organic phase solution is a terephthaloyl chloride n-hexane solution.

[0036] The ceramic membrane in step (3) is first immersed in an ethanol solution for ultrasonic cleaning to remove impurities on its surface and in its pores, and then immersed in an aqueous solution of sodium dodecyl sulfate (SDS) to increase the wettability of the ceramic membrane substrate;

[0037] The aqueous phase solution in step (3) is a piperazine aqueous solution, and the organic phase solution is a terephthaloyl chloride n-hexane solution.

[0038] The calcination procedure in step (1) is to heat to 700°C at 4°C / min, keep at this temperature for 2h, and cool naturally to room temperature.

[0039] The time for amino functionalization treatment in step (2) is 24 hours.

[0040] The concentrations of NH2-SiO2@SiC nanopowder in step (3) are 50, 100 and 200 mg / 100 ml.

[0041] The concentration of the SDS aqueous solution in step (3) is 0.5% (w / v), and the pore size of the ceramic membrane is in the range of 0.2-0.8 μm.

[0042] Step (4) The concentration of the oil-in-water emulsion is 67.5-250ppm, and the filtration pressure is 0.5-2bar

[0043] The concentration of the piperazine aqueous solution was 2% (w / v), and the concentration of the terephthaloyl chloride n-hexane solution was 0.15% (w / v).

[0044] Example 1: Step 1: 2 g of silicon carbide powder was placed in an alumina crucible and kept in a muffle furnace at 700°C for 2 hours with sufficient air. After the calcination reaction was completed, the SiO2@SiC was removed from the furnace and used for further reaction with APTES.

[0045] Step 2: 1 g of SiO2@SiC was dispersed in a round-bottom flask equipped with 100 mL of ethanol (95%) and a magnetic stirrer, and 5 mL of APTES was added to the stirring solution. The reaction was continued at room temperature for 24 hours to form a gray-black slurry, which was filtered to form a gray-black slurry. Excess ethanol and distilled water were used to remove the remaining unreacted materials and clean the product. The resulting product was completely dried in an oven at 50°C for 1 hour and finely ground using a grinder and pestle before analysis and further use.

[0046] Step 3: Ultrasonic clean the alumina ceramic membrane with a pore size of 0.5 μm in an ultrasonic environment for 20 minutes, then soak it in an ethanol solution for 1 hour to remove impurities on its surface and in the pores; then soak it in a 0.5% (w / v) SDS aqueous solution for 2 hours to increase the wettability of the ceramic support.

[0047] Step 4: Install the ceramic membrane pretreated in step 3 on a dead-end filtration device, add 0.1 g of NH2-SiO2@SiC powder to 100 mL of 2% (w / v) piperazine aqueous solution and ultrasonically treat for 15 minutes. Then, pass it as feed through the Al2O3 ceramic support at a constant pressure of 0.5 bar, and then dry it in an oven at 60°C for 15 minutes.

[0048] Step 5: The PIP-impregnated NH2-SiO2@SiC membrane obtained in Step 4 was exposed to a 0.15% (w / v) solution of terephthaloyl chloride in n-hexane. The IP reaction was continued for 10 minutes, and the membrane was washed with clean n-hexane to remove excess unreacted monomer. Finally, the membrane was cured in an oven at 60°C for 1 hour to obtain a SiO2@SiC / PA@Al2O3 ceramic nanofiltration membrane.

[0049] Step 6: Filter the 67.5 ppm oil-in-water emulsion through the ceramic nanofiltration membrane obtained in step 5 at a filtration pressure of 2 bar in a dead-end filtration mode.

[0050] Example 2: With other conditions unchanged, only the concentration of the oil-in-water emulsion was changed to 125 ppm, and the permeation flux of the membrane and the separation efficiency of the oil-in-water emulsion were investigated.

[0051] Example 3: With other conditions unchanged, only the concentration of the oil-in-water emulsion was changed to 250 ppm, and the permeation flux of the membrane and the separation efficiency of the oil-in-water emulsion were investigated.

[0052] The calculation formulas for permeation flux and separation efficiency are as follows:

[0053] Permeation flux (J) is defined as the volume (V) of water that passes through a unit membrane area (A) per unit time (t) under certain operating conditions. Its unit is LMH. The specific calculation formula is as follows:

[0054]

[0055] The calculation formula of the separation efficiency (R) of ceramic nanofiltration membrane for oil-in-water emulsion is as follows:

[0056]

[0057] C p and C f are the concentrations of oil-in-water emulsion in the permeate and feed liquid, respectively, and their concentrations are tested using a total organic carbon analyzer.

[0058] The test results are shown in the following table:

[0059] Example 1 2 3 Permeate flux (LMH) 76.05 45.68 21.22 Separation efficiency (%) 99.26 99.67 99.03

[0060] The test results showed that the ceramic nanofiltration membrane was successfully prepared.

[0061] Example 4

[0062] Other conditions remained unchanged, and the relationship between permeation flux and transmembrane pressure was measured using a 67.5 ppm oil-in-water emulsion as the feed. The transmembrane pressure was varied to 0.5 bar, 1 bar, and 1.5 bar, using the same conditions as in Example 1. The ceramic nanofiltration membrane increased from 21.22 LMH to 149.74 LMH when the pressure increased from 0.5 bar to 2 bar.

[0063] While embodiments of the present invention have been shown and described, it will be appreciated by those skilled in the art that various changes, modifications, substitutions, and variations may be made to these embodiments without departing from the principles and spirit of the invention, and that the scope of the invention is defined by the appended claims and their equivalents.

Claims

1. A method for preparing a novel nanopowder-modified ceramic composite nanofiltration membrane, characterized in that: The steps are as follows: Step (1): Weigh a certain amount of silicon carbide powder and place it in a crucible. Then, calcine it at a high temperature in a muffle furnace under air atmosphere. After the calcination reaction is completed, SiO2@SiC powder is obtained. Step (2): a certain mass of SiO2@SiC is dispersed in a round-bottom flask with a magnetic stirrer containing ethanol, and a certain volume of silane coupling agent KH-550 is added to the stirred solution to react, and amino-functionalized NH2-SiO2@SiC nanopowder is obtained by silane coupling treatment; Step (3): The alumina membrane is installed in a homemade coating device, a certain concentration of NH2-SiO2@SiC powder is added to an aqueous solution and ultrasonically dispersed, and then used as a feed through a ceramic carrier at a certain constant pressure, and compressed air is blown to the inner surface of the membrane tube until there are no water droplets on the surface, and then the membrane tube is vertically and quickly immersed in the organic phase solution for a certain contact time; after being taken out, it is washed with clean n-hexane to remove excess unreacted monomers, and then the membrane is placed in an oven for curing for a period of time, thereby obtaining a ceramic membrane named SiO2@SiC / PA@Al2O3; Step (4): filtering an oil-in-water emulsion of a certain concentration under a certain pressure in a dead-end filtration mode to test the performance of the ceramic nanofiltration membrane; The ceramic membrane in step (3) is first immersed in an ethanol solution for ultrasonic cleaning to remove impurities on its surface and in its pores, and then immersed in an aqueous solution of sodium dodecyl sulfate (SDS) to increase the wettability of the ceramic membrane substrate; The aqueous phase solution in the step (3) is a piperazine aqueous solution, and the organic phase solution is a terephthaloyl chloride n-hexane solution.

2. The method for preparing the novel nanopowder-modified ceramic composite nanofiltration membrane according to claim 1, characterized in that: The calcination procedure in step (1) is to heat to 700°C at 4°C / min, keep at this temperature for 2 h, and cool naturally to room temperature.

3. The method for preparing the novel nanopowder-modified ceramic composite nanofiltration membrane according to claim 1, characterized in that: The time for the amino functionalization treatment in step (2) is 24 h.

4. The method for preparing the novel nanopowder-modified ceramic composite nanofiltration membrane according to claim 1, wherein: The concentrations of the NH2-SiO2@SiC nanopowder in step (3) are 50, 100 and 200 mg / 100 ml.

5. The method for preparing the novel nanopowder-modified ceramic composite nanofiltration membrane according to claim 1, wherein: The concentration of the SDS aqueous solution in step (3) is 0.5% (w / v), and the pore size range of the ceramic membrane is 0.2-0.8 μm.

6. The method for preparing the novel nanopowder-modified ceramic composite nanofiltration membrane according to claim 1, characterized in that: In step (4), the concentration of the oil-in-water emulsion is 67.5-250 ppm, and the filtration pressure is 0.5-2 bar.

7. The preparation method according to any one of claims 1 to 6, characterized in that: The concentration of the piperazine aqueous solution is 2% (w / v), and the concentration of the terephthaloyl chloride n-hexane solution is 0.15% (w / v).

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