Preparation method of oleophobic hydrophilic silicon carbide ceramic membrane in air

Abstract

The invention discloses a preparation method of an oleophobic hydrophilic silicon carbide ceramic membrane in air. The perfluorodecyl acrylate is adopted to carry out oleophobic modification on the SiC ceramic membrane, methacrylic acid is selected as a hydrophilic monomer to be polymerized with the perfluorodecyl acrylate to keep the hydrophilicity of the SiC ceramic membrane, and finally the silicon carbide ceramic membrane which is oleophobic and hydrophilic in the air is prepared. The oil contact angle of the modified ceramic membrane in the air reaches 129 degrees, due to the oleophobicity of the modified ceramic membrane in the air, the water pre-wetting process can be omitted during filtration of the ceramic membrane, adhesion of oil drops is avoided, an oleophobic and hydrophilic surface in the air is constructed, and therefore the pollution process of the membrane is slowed down. Compared with a porous SiC ceramic membrane, an Al2O3 ceramic membrane and the like, the modified SiC ceramic membrane has the advantages that the anti-pollution capacity is obviously improved, and the flux attenuation rate is obviously reduced.

Description

Technical Field

[0001] The present invention belongs to the technical field of separation membrane materials, and relates to a method for preparing an oleophobic and hydrophilic silicon carbide ceramic membrane in air, in particular to a method for preparing an oleophobic and hydrophilic silicon carbide ceramic membrane by surface modification of a SiC ceramic membrane through a photopolymerization method. Background Art

[0002] In modern society, a large amount of oily wastewater is produced during the extraction, transportation and use of oil in chemical plants. How to efficiently separate these surfactant-stabilized water-in-oil emulsions is the current research focus. However, due to the low interfacial tension between the two phases, traditional separation technologies are quite challenging. As an advanced separation technology, membrane separation technology has significant technical and economic advantages such as low energy consumption, easy operation and small footprint, and has been widely studied in the field of oil-water separation. As an emerging member of inorganic ceramic membranes, silicon carbide membranes have become a research hotspot in recent years due to their high porosity, unique electronegativity and surface hydrophilicity. However, in the process of using SiC membranes to treat emulsified oil wastewater, membrane fouling and treatment efficiency remain key issues. To this end, scholars at home and abroad have invented different methods and strategies to improve the anti-fouling ability of ceramic membranes in the oil-water separation process.

[0003] For example, China's invention patent CN117865719A reports a method for plasma modification of silicon carbide ceramic membranes. The prepared silicon carbide membrane has super oleophobicity underwater and high stability, and has good application prospects in the field of oil-water separation. China's invention patent CN117510235A reports a method for modifying silicon carbide membranes with a suspension of silicon dioxide nanoparticles. The resulting silicon carbide modified membrane has super hydrophilicity-underwater super oleophobicity, and has the advantages of small membrane pore size, good durability, high oil-water separation efficiency, good friction resistance, and good corrosion resistance. China's invention patent CN115245752B reports a method for covalently grafting para-acyl chloride pyridine to the surface and pore wall of a ceramic membrane, and then axially coordinating perfluorometal phthalocyanine through the N element on the pyridine ring, to prepare a super hydrophobic functional layer on the ceramic membrane. The super hydrophobic ceramic membrane prepared by this method has a simple preparation process, mild preparation conditions, and good hydrophobic properties.

[0004] However, it can be found that these existing modification methods mainly focus on regulating the hydrophilicity and hydrophobicity of SiC membranes, while less attention is paid to regulating the oleophobicity of its surface in the air. Considering that membrane contamination begins when the feed liquid contacts the membrane surface, a membrane with a hydrophilic and oleophobic surface in the air can avoid the adhesion of oil droplets when it initially contacts the oil-water emulsion, thereby slowing down the membrane contamination process. The present invention polymerizes oleophobic perfluorodecyl acrylate and hydrophilic methacrylic acid on the surface of the SiC membrane by photopolymerization, constructing an oleophobic and hydrophilic surface in the air, which greatly delays the flux attenuation process of the SiC ceramic membrane in the process of oil-water separation. Summary of the invention

[0005] The present invention discloses a method for preparing an oleophobic and hydrophilic silicon carbide ceramic membrane in air. Different from the above publicly reported method, the present invention proposes a method for surface modification of SiC ceramic membrane by photopolymerization, so that it exhibits hydrophilic and oleophobic properties in air, thereby improving the oil-water separation performance of SiC ceramic membrane.

[0006] To achieve the above purpose, the technical solution adopted by the present invention is as follows: (1) mixing perfluorodecyl acrylate and methacrylic acid in a certain ratio; (2) adding polyethylene glycol diacrylate to the mixed solution of step (1) to promote the polymerization of perfluorodecyl acrylate and methacrylic acid in the solution, adding 2-hydroxy-2-methyl-1-phenylpropanone as a photoinitiator, and adding acetone as a solvent to prepare a final modified solution; (3) Wrap one side of the SiC ceramic diaphragm with raw tape and immerse it vertically into the modified solution; (4) taking out the SiC ceramic diaphragm impregnated in step (3), placing it in a UV light box with the side not wrapped with the raw tape facing upward for irradiation; (5) Take out the SiC ceramic diaphragm in step (4) and cool it to room temperature.

[0007] Preferably, the mass ratio of perfluorodecyl acrylate to methacrylic acid in the modified solution in step (1) is 1:0.5-1.5.

[0008] Preferably, in step (2), the amount of polyethylene glycol diacrylate added is 5.3% to 8.4%, the amount of 2-hydroxy-2-methyl-1-phenylpropanone added is 0.7% to 1.0%, and the amount of acetone added is 53.8% to 62.0%, and the above addition amount ratio is the mass of the component added / the total mass of the modified solution.

[0009] Preferably, the immersion time of the SiC ceramic film in step 3) is 30 to 60 minutes.

[0010] Preferably, the ultraviolet light irradiation time of the SiC ceramic film in step (4) is 60 to 120 minutes.

[0011] Compared with the prior art, the present invention has the following beneficial effects: 1. The present invention discloses a method for surface modification of SiC ceramic membrane by photopolymerization, wherein the modified SiC ceramic membrane exhibits hydrophilic and oleophobic properties in the air.

[0012] 2. The surface of the modified SiC ceramic membrane avoids the contamination of the initial oily liquid when it comes into contact with the membrane surface, thereby greatly slowing down the flux attenuation rate of the membrane and improving the stable flux.

[0013] 3. The conventional SiC ceramic membrane has a low feed liquid processing capacity and a slow filtration rate due to its fast flux decay. The modified SiC ceramic membrane in the present invention has a faster filtration rate than the original membrane and can process more feed liquid in the same time. BRIEF DESCRIPTION OF THE DRAWINGS

[0014] Figure 1 This is the oil contact angle of the SiC ceramic film prepared in Example 1 in air.

[0015] Figure 2 FTIR spectra of the SiC ceramic film prepared in Example 2 and the original film.

[0016] Figure 3 The flux change between the SiC ceramic membrane prepared in Example 3 and the original membrane when filtering 1000 ppm oil-in-water emulsion.

[0017] Figure 4 The flux changes of the SiC ceramic membrane prepared in Example 4 and the original membrane in filtering oil-in-water emulsions of different concentrations. DETAILED DESCRIPTION

[0018] The present invention is described in detail below in conjunction with the accompanying drawings and specific embodiments. The following embodiments are only used to illustrate the present invention, but are not used to limit the scope of implementation of the present invention. Example 1

[0019] A method for preparing an oleophobic and hydrophilic silicon carbide ceramic membrane in air, the specific steps of which are as follows: (1) mixing perfluorodecyl acrylate and methacrylic acid in a mass ratio of 1:1 to prepare a modified solution; (2) Add 5.3% polyethylene glycol diacrylate to the modified solution of step (1) to promote the polymerization of perfluorodecyl acrylate and methacrylic acid in the solution, add 0.7% 2-hydroxy-2-methyl-1-phenylpropanone as a photoinitiator, and add 53.8% acetone as a solvent to prepare a final modified solution; the ratio of the added amount of the above components is the added mass of the component / the total mass of the modified solution.

[0020] (3) After wrapping one side of the SiC ceramic diaphragm with raw tape, immerse it vertically into the modified solution for 30 minutes; (4) taking out the SiC ceramic diaphragm impregnated in step (3), placing it in a UV light box with the side not wrapped with raw tape facing upward, and irradiating it for 60 min; (5) Take out the SiC ceramic diaphragm in step (4) and cool it to room temperature.

[0021] The surface oil contact angle in air was measured using an optical contact angle meter. Figure 1 It can be seen that the oil contact angle of the modified SiC ceramic film in air is 129°. Example 2

[0022] A method for preparing an oleophobic and hydrophilic silicon carbide ceramic membrane in air, the specific steps of which are as follows: (1) mixing perfluorodecyl acrylate and methacrylic acid in a mass ratio of 1:0.5 to prepare a modified solution; (2) 5.76% polyethylene glycol diacrylate was added to the modified solution of step (1) to promote the polymerization of perfluorodecyl acrylate and methacrylic acid in the solution, 0.71% 2-hydroxy-2-methyl-1-phenylpropanone was added as a photoinitiator, and 57.6% acetone was added as a solvent to prepare a final modified solution; the ratio of the added amount of the above components was the added mass of the component / the total mass of the modified solution.

[0023] (3) After wrapping one side of the SiC ceramic diaphragm with raw tape, immerse it vertically into the modified solution for 40 minutes; (4) taking out the SiC ceramic diaphragm impregnated in step (3), placing it in a UV light box with the side not wrapped with raw tape facing upward, and irradiating it for 90 min; (5) Take out the SiC ceramic diaphragm in step (4) and cool it to room temperature.

[0024] The surface composition of the modified SiC ceramic film was analyzed by Fourier transform infrared spectrometer. Figure 2 The vertical axis is the peak intensity, and the horizontal axis is the wavelength. The three samples in the figure are the modified film without photopolymerization, the modified film after photopolymerization, and the original film from top to bottom. Figure 2It can be seen that compared with the original film and the modified film without photopolymerization, the surface of the modified film prepared by photopolymerization is 1000-1350cm -1 The CF bond is significantly enhanced. Example 3

[0025] A method for preparing an oleophobic and hydrophilic silicon carbide ceramic membrane in air, the specific steps of which are as follows: (1) mixing perfluorodecyl acrylate and methacrylic acid in a mass ratio of 1:1.5 to prepare a modified solution; (2) 6.2% polyethylene glycol diacrylate was added to the modified solution of step (1) to promote the polymerization of perfluorodecyl acrylate and methacrylic acid in the solution, 0.8% 2-hydroxy-2-methyl-1-phenylpropanone was added as a photoinitiator, and 58.2% acetone was added as a solvent to prepare a final modified solution; the ratio of the added amount of the above components was the added mass of the component / the total mass of the modified solution.

[0026] (3) After wrapping one side of the SiC ceramic diaphragm with raw tape, immerse it vertically into the modified solution for 30 minutes; (4) taking out the SiC ceramic diaphragm impregnated in step (3), placing it in a UV light box with the side not wrapped with raw tape facing upward, and irradiating it for 120 min; (5) Take out the SiC ceramic diaphragm in step (4) and cool it to room temperature.

[0027] The oil-in-water emulsion with a concentration of 1000 ppm was filtered using a cross-flow filtration device at 20 °C, a transmembrane pressure of 0.9 bar, and a membrane flow rate of 1 m / s. Figure 3 The vertical axis is the flux attenuation rate, and the horizontal axis is time. The samples in the figure are the original film and the modified film after photopolymerization. Figure 3 It can be seen that the flux decay rate of the photopolymerized modified membrane is significantly lower than that of the original membrane. Example 4

[0028] A method for preparing an oleophobic and hydrophilic silicon carbide ceramic membrane in air, the specific steps of which are as follows: (1) mixing perfluorodecyl acrylate and methacrylic acid in a mass ratio of 1:1.2 to prepare a modified solution; (2) Add 6.5% polyethylene glycol diacrylate to the modified solution of step (1) to promote the polymerization of perfluorodecyl acrylate and methacrylic acid in the solution, add 0.81% 2-hydroxy-2-methyl-1-phenylpropanone as a photoinitiator, and add 62% acetone as a solvent to prepare the final modified solution; the ratio of the added amount of the above components is the added mass of the component / the total mass of the modified solution.

[0029] (3) After wrapping one side of the SiC ceramic diaphragm with raw tape, immerse it vertically into the modified solution for 60 minutes; (4) taking out the SiC ceramic diaphragm impregnated in step (3), placing it in a UV light box with the side not wrapped with raw tape facing upward, and irradiating it for 60 min; (5) Take out the SiC ceramic diaphragm in step (4) and cool it to room temperature.

[0030] The oil-in-water emulsion with a concentration of 2000 ppm was filtered using a cross-flow filtration device at 20 °C, a transmembrane pressure of 0.9 bar, and a membrane flow rate of 1 m / s. Figure 4 The vertical axis is the flux attenuation, and the horizontal axis is the time. The samples in the figure are the original film and the modified film after photopolymerization. Figure 4 It can be seen that the initial flux and stable flux of the photopolymerized modified membrane are higher than those of the original membrane. Example 5

[0031] A method for preparing an oleophobic and hydrophilic silicon carbide ceramic membrane in air, the specific steps of which are as follows: (1) mixing perfluorodecyl acrylate and methacrylic acid in a mass ratio of 1:1.2 to prepare a modified solution; (2) 8.4% polyethylene glycol diacrylate was added to the modified solution of step (1) to promote the polymerization of perfluorodecyl acrylate and methacrylic acid in the solution, 1% 2-hydroxy-2-methyl-1-phenylpropanone was added as a photoinitiator, and 60.1% acetone was added as a solvent to prepare a final modified solution; the ratio of the added amount of the above components was the added mass of the component / the total mass of the modified solution.

[0032] (3) After wrapping one side of the SiC ceramic diaphragm with raw tape, immerse it vertically into the modified solution for 60 minutes; (4) taking out the SiC ceramic diaphragm impregnated in step (3), placing it in a UV light box with the side not wrapped with raw tape facing upward, and irradiating it for 60 min; (5) Take out the SiC ceramic diaphragm in step (4) and cool it to room temperature.

Claims

1. A method for preparing an oleophobic and hydrophilic silicon carbide ceramic membrane in air, characterized in that: The specific steps are as follows: (1) mixing perfluorodecyl acrylate and methacrylic acid in a certain ratio; (2) adding polyethylene glycol diacrylate to the mixed solution of step (1) to promote the polymerization of perfluorodecyl acrylate and methacrylic acid in the solution, adding 2-hydroxy-2-methyl-1-phenylpropanone as a photoinitiator, and adding acetone as a solvent to prepare a final modified solution; (3) Wrap one side of the SiC ceramic diaphragm with raw tape and immerse it vertically into the modified solution; (4) taking out the SiC ceramic diaphragm impregnated in step (3), placing it in a UV light box with the side not wrapped with the raw tape facing upward for irradiation; (5) Take out the SiC ceramic diaphragm in step (4) and cool it to room temperature.

2. A method for preparing an oleophobic and hydrophilic silicon carbide ceramic membrane in air according to claim 1, characterized in that: The mass ratio of perfluorodecyl acrylate to methacrylic acid in the modified solution described in step (1) is 1:0.5-1.

5.

3. The method for preparing an oleophobic and hydrophilic silicon carbide ceramic membrane in air according to claim 1, characterized in that: The amount of polyethylene glycol diacrylate added in step (2) is 5.3% to 8.4%, the amount of 2-hydroxy-2-methyl-1-phenylpropanone added is 0.7% to 1%, and the amount of acetone added is 53.8% to 62.0%. The above addition amount ratio is the mass of component addition / total mass of modified solution.

4. The method for preparing a highly oleophobic and hydrophilic silicon carbide ceramic membrane in air according to claim 1, characterized in that: The immersion time in step (3) is 30 to 60 minutes.

5. The method for preparing a highly oleophobic and hydrophilic silicon carbide ceramic membrane in air according to claim 1, characterized in that: The ultraviolet light irradiation time in step (4) is 60 to 120 minutes.

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