Oil-water separation membrane material and preparation method thereof

Abstract

The invention provides an oil-water separation membrane material and a preparation method thereof, and relates to the technical field of membrane materials. The preparation method comprises the following steps: putting PVDF powder into an alkaline solution, stirring and activating, filtering, washing to be neutral, and drying to obtain activated PVDF; the preparation method comprises the following steps: activating PVDF in a solvent, dissolving the activated PVDF in the solvent, adding vinyl pyrrolidone and azodiisobutyronitrile under the protection of inert gas, and then carrying out polymerization reaction to obtain a PVDF-g-PVP copolymer; then adding polysiloxane containing vinyl terminal functionalization to react with the copolymer of the PVDF-g-PVP, so as to obtain a multi-block copolymer of the PVDF-g-PVP-g-PDMS (Polydimethylsiloxane-g-Polyvinyl Pyrrolidone-g-Polydimethylsiloxane); washing and drying the multi-block copolymer of the PVDF-g-PVP-g-PDMS, and then dissolving the multi-block copolymer of the PVDF-g-PVP-g-PDMS in triethyl phosphate to obtain a membrane casting solution; and finally, uniformly coating the surface of a base material with the membrane casting solution, then immersing the base material in a coagulating bath for coagulating, and then transferring the base material into pure water for soaking to obtain the oil-water separation membrane material. The prepared membrane material can improve the oil-water separation effect and has a relatively high application prospect.

Description

Technical Field

[0001] The invention relates to the technical field of membrane materials, and in particular to a method for preparing an oil-water separation membrane material. Background Art

[0002] With the rapid development of the economy, the balance of the ecological environment has been gradually broken, and the global environmental problems faced by mankind have become increasingly severe. Among them, water pollution is particularly prominent. For example, industries such as textiles, food, leather, mining and metal processing will produce a large amount of oily wastewater. Oil spills may occur in the exploration, production, refining and transportation stages of the petroleum industry, causing serious environmental pollution and economic losses. Therefore, whether it is the routine treatment of oily wastewater or the emergency treatment of oil spills, efficient and practical oil-water separation technology is urgently needed. At present, traditional oil-water separation technologies include gravity separation, centrifugal separation, physical adsorption, flocculation, electrochemical and biological methods. These technologies have the disadvantages of low separation efficiency, poor separation capacity, high energy consumption, and possible secondary pollution. Therefore, it is very important to develop economical, environmentally friendly and efficient oil-water separation technology.

[0003] In recent years, the wettability of material surfaces has attracted much attention. Wettability is an inherent property of solid surfaces. The wettability of materials can be observed through the wetting phenomenon of droplets on solid surfaces, which includes various states such as hydrophilicity and lipophilicity. The wettability of materials is mainly achieved by changing the chemical composition of the material surface and constructing a multi-level structure on the material surface. The core technology of the oil-water membrane separation process is the construction of the membrane surface wettability. If the membrane material has both hydrophobicity and lipophilicity, it can selectively filter oil in the oil-water mixture. Similarly, if the membrane material has both hydrophilicity and underwater lipophobicity, it can filter water in the oil-water mixture. Combining the advantages of the separation membrane, by chemically modifying the membrane surface and constructing a multi-level structure, the membrane has specific wettability, which not only improves the efficiency of oil-water separation, but also expands its scope of application. Summary of the invention

[0004] In view of this, the present invention provides a novel oil-water separation membrane material and a preparation method thereof. The present invention is implemented by adopting the following technical solutions: A method for preparing an oil-water separation membrane material comprises the following steps: (1) placing PVDF powder in an alkaline solution for stirring and activation, filtering and washing to neutrality, and drying to obtain activated PVDF; (2) dissolving the activated PVDF in a solvent, adding vinyl pyrrolidone and azobisisobutyronitrile under the protection of an inert gas, and then performing a polymerization reaction to obtain a PVDF-g-PVP copolymer; (3) adding polysiloxane containing vinyl terminal functionalization to react with the PVDF-g-PVP copolymer to obtain a multi-block copolymer of PVDF-g-PVP-g-PDMS; (4) washing and drying the PVDF-g-PVP-g-PDMS multi-block copolymer, and then dissolving it in triethyl phosphate to obtain a casting solution; (5) The casting liquid is uniformly coated on the surface of the substrate, and then immersed in a coagulation bath for coagulation, and then immersed in pure water to obtain an oil-water separation membrane material.

[0005] Preferably, the alkaline solution in step (1) is prepared by mixing ethanol, sodium hydroxide and water.

[0006] Preferably, the inert gas in step (2) is nitrogen.

[0007] Preferably, in step (2), vinyl pyrrolidone can be replaced by hydroxyethyl methacrylate or methacrylate.

[0008] Preferably, azobisisobutyronitrile in step (2) can be replaced by benzoyl peroxide.

[0009] Preferably, the vinyl-terminated functionalized polysiloxane in step (3) includes vinyl polydimethylsiloxane, vinyl polytrifluoropropyl methylsiloxane, and vinyl polyphenyl methylsiloxane.

[0010] Preferably, in step (4), triethyl phosphate can be replaced by N,N-dimethylformamide, N,N-dimethylacetamide, N-methylpyrrolidone and dimethyl sulfoxide.

[0011] Compared with the prior art, the present invention has the following beneficial effects: The present invention provides an oil-water separation membrane material and a preparation method thereof. The present invention obtains a PVDF-g-PVP-g-PDMS multi-block copolymer by modifying PVDF, and then uses the copolymer to make a casting solution, and obtains a novel membrane material after solidification. After a large number of experimental tests, the membrane material of the present invention has a high oil-water separation effect and has a high application prospect. DETAILED DESCRIPTION

[0012] The present invention will be further described below in conjunction with the embodiments.

[0013] Example 1 A method for preparing an oil-water separation membrane material comprises the following steps: (1) Placing PVDF powder in an alkaline solution for stirring and activation, filtering and washing to neutrality, and drying to obtain activated PVDF; wherein the alkaline solution is prepared by mixing ethanol, sodium hydroxide and water; (2) dissolving the activated PVDF in a solvent, adding vinyl pyrrolidone and azobisisobutyronitrile under nitrogen protection, and then performing a polymerization reaction to obtain a PVDF-g-PVP copolymer; (3) adding vinyl polydimethylsiloxane to react with the PVDF-g-PVP copolymer to obtain a multi-block copolymer of PVDF-g-PVP-g-PDMS; (4) washing and drying the PVDF-g-PVP-g-PDMS multi-block copolymer, and then dissolving it in triethyl phosphate to obtain a casting solution; (5) The casting liquid is uniformly coated on the surface of the substrate, and then immersed in a coagulation bath for coagulation, and then immersed in pure water to obtain an oil-water separation membrane material.

[0014] Example 2 A method for preparing an oil-water separation membrane material comprises the following steps: (1) Placing PVDF powder in an alkaline solution for stirring and activation, filtering and washing to neutrality, and drying to obtain activated PVDF; wherein the alkaline solution is prepared by mixing ethanol, sodium hydroxide and water; (2) dissolving the activated PVDF in a solvent, adding vinyl pyrrolidone and azobisisobutyronitrile under nitrogen protection, and then performing a polymerization reaction to obtain a PVDF-g-PVP copolymer; (3) adding vinyl polytrifluoropropyl methylsiloxane to react with the PVDF-g-PVP copolymer to obtain a multi-block copolymer of PVDF-g-PVP-g-PDMS; (4) washing and drying the PVDF-g-PVP-g-PDMS multi-block copolymer, and then dissolving it in triethyl phosphate to obtain a casting solution; (5) The casting liquid is uniformly coated on the surface of the substrate, and then immersed in a coagulation bath for coagulation, and then immersed in pure water to obtain an oil-water separation membrane material.

[0015] Example 3 A method for preparing an oil-water separation membrane material comprises the following steps: (1) Placing PVDF powder in an alkaline solution for stirring and activation, filtering and washing to neutrality, and drying to obtain activated PVDF; wherein the alkaline solution is prepared by mixing ethanol, sodium hydroxide and water; (2) dissolving the activated PVDF in a solvent, adding vinyl pyrrolidone and azobisisobutyronitrile under nitrogen protection, and then performing a polymerization reaction to obtain a PVDF-g-PVP copolymer; (3) adding vinyl polyphenylmethylsiloxane to react with the PVDF-g-PVP copolymer to obtain a multi-block copolymer of PVDF-g-PVP-g-PDMS; (4) washing and drying the PVDF-g-PVP-g-PDMS multi-block copolymer, and then dissolving it in triethyl phosphate to obtain a casting solution; (5) The casting liquid is uniformly coated on the surface of the substrate, and then immersed in a coagulation bath for coagulation, and then immersed in pure water to obtain an oil-water separation membrane material.

[0016] Example 4 A method for preparing an oil-water separation membrane material comprises the following steps: (1) Placing PVDF powder in an alkaline solution for stirring and activation, filtering and washing to neutrality, and drying to obtain activated PVDF; wherein the alkaline solution is prepared by mixing ethanol, sodium hydroxide and water; (2) dissolving the activated PVDF in a solvent, adding hydroxyethyl methacrylate and benzoyl peroxide under nitrogen protection, and then performing a polymerization reaction to obtain a PVDF-g-PVP copolymer; (3) adding vinyl polydimethylsiloxane to react with the PVDF-g-PVP copolymer to obtain a multi-block copolymer of PVDF-g-PVP-g-PDMS; (4) washing and drying the PVDF-g-PVP-g-PDMS multi-block copolymer, and then dissolving it in triethyl phosphate to obtain a casting solution; (5) The casting liquid is uniformly coated on the surface of the substrate, and then immersed in a coagulation bath for coagulation, and then immersed in pure water to obtain an oil-water separation membrane material.

[0017] Example 5 A method for preparing an oil-water separation membrane material comprises the following steps: (1) Placing PVDF powder in an alkaline solution for stirring and activation, filtering and washing to neutrality, and drying to obtain activated PVDF; wherein the alkaline solution is prepared by mixing ethanol, sodium hydroxide and water; (2) dissolving the activated PVDF in a solvent, adding methacrylate and benzoyl peroxide under nitrogen protection, and then performing a polymerization reaction to obtain a PVDF-g-PVP copolymer; (3) adding vinyl polydimethylsiloxane to react with the PVDF-g-PVP copolymer to obtain a multi-block copolymer of PVDF-g-PVP-g-PDMS; (4) washing and drying the PVDF-g-PVP-g-PDMS multi-block copolymer, and then dissolving it in triethyl phosphate to obtain a casting solution; (5) The casting liquid is uniformly coated on the surface of the substrate, and then immersed in a coagulation bath for coagulation, and then immersed in pure water to obtain an oil-water separation membrane material.

[0018] Example 6 A method for preparing an oil-water separation membrane material comprises the following steps: (1) Placing PVDF powder in an alkaline solution for stirring and activation, filtering and washing to neutrality, and drying to obtain activated PVDF; wherein the alkaline solution is prepared by mixing ethanol, sodium hydroxide and water; (2) dissolving the activated PVDF in a solvent, adding vinyl pyrrolidone and azobisisobutyronitrile under nitrogen protection, and then performing a polymerization reaction to obtain a PVDF-g-PVP copolymer; (3) adding vinyl polydimethylsiloxane to react with the PVDF-g-PVP copolymer to obtain a multi-block copolymer of PVDF-g-PVP-g-PDMS; (4) washing and drying the PVDF-g-PVP-g-PDMS multi-block copolymer, and then dissolving it in N,N-dimethylformamide to obtain a casting solution; (5) The casting liquid is uniformly coated on the surface of the substrate, and then immersed in a coagulation bath for coagulation, and then immersed in pure water to obtain an oil-water separation membrane material.

[0019] Example 7 A method for preparing an oil-water separation membrane material comprises the following steps: (1) Placing PVDF powder in an alkaline solution for stirring and activation, filtering and washing to neutrality, and drying to obtain activated PVDF; wherein the alkaline solution is prepared by mixing ethanol, sodium hydroxide and water; (2) dissolving the activated PVDF in a solvent, adding vinyl pyrrolidone and azobisisobutyronitrile under nitrogen protection, and then performing a polymerization reaction to obtain a PVDF-g-PVP copolymer; (3) adding vinyl polydimethylsiloxane to react with the PVDF-g-PVP copolymer to obtain a multi-block copolymer of PVDF-g-PVP-g-PDMS; (4) washing and drying the PVDF-g-PVP-g-PDMS multi-block copolymer, and then dissolving it in N,N-dimethylacetamide to obtain a casting solution; (5) The casting liquid is uniformly coated on the surface of the substrate, and then immersed in a coagulation bath for coagulation, and then immersed in pure water to obtain an oil-water separation membrane material.

[0020] Example 8 A method for preparing an oil-water separation membrane material comprises the following steps: (1) Placing PVDF powder in an alkaline solution for stirring and activation, filtering and washing to neutrality, and drying to obtain activated PVDF; wherein the alkaline solution is prepared by mixing ethanol, sodium hydroxide and water; (2) dissolving the activated PVDF in a solvent, adding vinyl pyrrolidone and azobisisobutyronitrile under nitrogen protection, and then performing a polymerization reaction to obtain a PVDF-g-PVP copolymer; (3) adding vinyl polydimethylsiloxane to react with the PVDF-g-PVP copolymer to obtain a multi-block copolymer of PVDF-g-PVP-g-PDMS; (4) washing and drying the PVDF-g-PVP-g-PDMS multi-block copolymer, and then dissolving it in N-methylpyrrolidone to obtain a casting solution; (5) The casting liquid is uniformly coated on the surface of the substrate, and then immersed in a coagulation bath for coagulation, and then immersed in pure water to obtain an oil-water separation membrane material.

[0021] Example 9 A method for preparing an oil-water separation membrane material comprises the following steps: (1) Placing PVDF powder in an alkaline solution for stirring and activation, filtering and washing to neutrality, and drying to obtain activated PVDF; wherein the alkaline solution is prepared by mixing ethanol, sodium hydroxide and water; (2) dissolving the activated PVDF in a solvent, adding vinyl pyrrolidone and azobisisobutyronitrile under nitrogen protection, and then performing a polymerization reaction to obtain a PVDF-g-PVP copolymer; (3) adding vinyl polydimethylsiloxane to react with the PVDF-g-PVP copolymer to obtain a multi-block copolymer of PVDF-g-PVP-g-PDMS; (4) washing and drying the PVDF-g-PVP-g-PDMS multi-block copolymer, and then dissolving it in dimethyl sulfoxide to obtain a casting solution; (5) The casting liquid is uniformly coated on the surface of the substrate, and then immersed in a coagulation bath for coagulation, and then immersed in pure water to obtain an oil-water separation membrane material.

[0022] The membrane material prepared in the embodiment was subjected to an oil-water separation experiment. The specific experimental method was to sandwich the prepared membrane material between two glass containers, measure the volume of liquid passing through the filter membrane in a certain period of time, and evaluate the performance of the filter membrane. The oil-water emulsion was prepared by mixing equal volumes of n-dodecane, n-hexadecane, soybean oil, gasoline and water.

[0023] In order to visually observe the oil-water separation performance of the membrane, the water phase was dyed blue with methylene blue and the oil phase was dyed red with Sudan red. The oil-water separation efficiency was calculated as the ratio of the mass of oil before and after separation in the oil-water emulsion.

[0024] The interception rate of the membrane material of the invention to n-dodecane and n-hexadecane in oil-water emulsion is greater than 99%, and the interception rate to soybean oil and gasoline oil is greater than 94%.

[0025] The above is only a preferred embodiment of the present invention. It should be pointed out that for ordinary technicians in this technical field, several improvements and modifications can be made without departing from the principle of the present invention. These improvements and modifications should also be regarded as the scope of protection of the present invention.

Claims

1. A method for preparing an oil-water separation membrane material, characterized in that: The following steps are involved: (1) placing PVDF powder in an alkaline solution for stirring and activation, filtering and washing to neutrality, and drying to obtain activated PVDF; (2) dissolving the activated PVDF in a solvent, adding vinyl pyrrolidone and azobisisobutyronitrile under the protection of an inert gas, and then performing a polymerization reaction to obtain a PVDF-g-PVP copolymer; (3) adding polysiloxane containing vinyl terminal functionalization to react with the PVDF-g-PVP copolymer to obtain a multi-block copolymer of PVDF-g-PVP-g-PDMS; (4) washing and drying the PVDF-g-PVP-g-PDMS multi-block copolymer, and then dissolving it in triethyl phosphate to obtain a casting solution; (5) The casting liquid is uniformly coated on the surface of the substrate, and then immersed in a coagulation bath for coagulation, and then immersed in pure water to obtain an oil-water separation membrane material.

2. The preparation method according to claim 1, characterized in that The alkaline solution in step (1) is prepared by mixing ethanol, sodium hydroxide and water.

3. The preparation method according to claim 1, characterized in that: The inert gas in step (2) is nitrogen.

4. The preparation method according to claim 1, characterized in that: In step (2), vinyl pyrrolidone can be replaced by hydroxyethyl methacrylate or methacrylate.

5. The preparation method according to claim 1, characterized in that: In step (2), azobisisobutyronitrile can be replaced by benzoyl peroxide.

6. The preparation method according to claim 1, characterized in that: The vinyl-terminated functionalized polysiloxane in step (3) includes vinyl polydimethylsiloxane, vinyl polytrifluoropropyl methylsiloxane, and vinyl polyphenyl methylsiloxane.

7. The preparation method according to claim 1, characterized in that: In step (4), triethyl phosphate can be replaced by N,N-dimethylformamide, N,N-dimethylacetamide, N-methylpyrrolidone and dimethyl sulfoxide.

8. An oil-water separation membrane material, characterized in that: Prepared by any one of the methods of claims 1 to 7.