An underwater superoleophobic porous material with high oil resistance and its preparation method

Abstract

This invention discloses an underwater superoleophobic porous material with high oil resistance and its preparation method, belonging to the field of material preparation technology. The material addresses the problem of performance degradation caused by oil adhesion and clogging in existing underwater superoleophobic materials by sequentially constructing polyvinylidene fluoride / tannic acid-Fe on the surface of a polyvinylidene fluoride porous membrane. 3＋ This material is obtained by grafting a hydrophilic layer with amino-modified flexible molecular brush nanoparticles. This composite structure not only endows the material with excellent underwater superoleophobicity but also enables the capture, aggregation, and release of oil through the dynamic action of the surface flexible molecular brushes, thus giving the material superior oil resistance and self-cleaning capabilities. Under vacuum assistance, this material can achieve efficient and continuous separation of surfactant-stabilized oil-in-water emulsions, showing broad application prospects in oily wastewater treatment and oil spill recovery.

Description

Technical Field

[0001] This invention belongs to the field of materials preparation technology, specifically relating to an underwater superoleophobic porous material with high oil resistance and its preparation method. Background Technology

[0002] With the rapid development of global industrialization, the leakage accidents during oil extraction and transportation, as well as the oily wastewater discharged from industries such as machining and chemical production, are increasing, posing a serious threat to the aquatic ecological environment and human health. Therefore, the development of efficient and environmentally friendly oil-water separation technologies and materials has become a research hotspot in the fields of environmental engineering and materials science.

[0003] Currently, traditional oil-water separation technologies mainly include gravity sedimentation, centrifugal separation, chemical flocculation, adsorption, and membrane filtration. Although these methods can achieve oil-water separation under certain conditions, they generally suffer from problems such as limited separation efficiency, high energy consumption, complex operation, easy generation of secondary pollution, or difficulty in treating emulsified oil droplets (especially oil-in-water emulsions). Therefore, developing new separation materials that are low-cost, environmentally friendly, and can efficiently treat various types of oily wastewater is of great practical significance.

[0004] In recent years, inspired by the special wettability of biological surfaces in nature, interface materials with special wettability (such as superhydrophobic / superoleophilic or superhydrophilic / underwater superoleophobic) have shown great potential in the field of oil-water separation. In particular, underwater superoleophobic materials exhibit a strong repulsion effect on oil droplets in the aquatic environment, allowing the aqueous phase to pass through while effectively trapping the oil phase. Theoretically, they are very suitable for removing oily pollutants from water. Researchers have successfully prepared a variety of porous substrates (such as metal meshes, fabrics, sponges, porous membranes, etc.) with underwater superoleophobic properties through various methods (such as surface coating, chemical modification, and construction of micro-nano structures) for the separation of oil-water mixtures or emulsions.

[0005] However, in practical applications, especially in complex oily environments, these materials still face significant challenges. Oily contaminants (especially high-viscosity crude oil or complex oils containing surfactants) easily adhere to, adsorb, or even penetrate into the material surface and pore structure, causing oil accumulation, pore blockage, or damage to the chemical modification layer. This contamination leads to a sharp decline in the underwater superoleophobic properties of the material, reduced flux, decreased separation efficiency, shortened service life, and even the need for frequent cleaning or replacement, severely restricting the feasibility of its continuous and large-scale application. Therefore, the simple underwater superoleophobic properties are no longer sufficient to meet the requirements for long-term, pollution-resistant separation in complex environments.

[0006] To address the aforementioned issues, there is an urgent need to develop a new type of material that not only possesses excellent underwater superoleophobic properties but also effectively resists the adhesion and contamination of various oils. This material should maintain excellent anti-oil properties during long-term, continuous oil-water separation processes, significantly extending the material's service life and reducing maintenance costs. This would promote the development and application of efficient, durable, and practical oil-water separation technology. Summary of the Invention

[0007] This invention addresses the problem that existing underwater superoleophobic materials have insufficient resistance to oil pollution and are easily adhered or clogged by oil, leading to performance degradation. By using a composite structure of polyvinylidene fluoride porous membrane substrate-hydrophilic layer-amino-modified flexible molecular brush nanoparticles, an underwater superoleophobic porous material with high oil resistance is prepared.

[0008] The present invention provides a method for preparing underwater superoleophobic porous materials with high oil resistance, which involves constructing a stable polyvinyl alcohol / tannic acid-Fe layer on the surface of a polyvinylidene fluoride porous membrane via a solution immersion method. 3+ A hydrophilic layer is formed, and then amino-modified flexible molecular brush nanoparticles are chemically grafted onto the hydrophilic layer to prepare an underwater superoleophobic porous material with high oil resistance.

[0009] In this structure, the hydrophilic layer can firmly bind water molecules in an aqueous environment to form a stable hydration layer, effectively isolating the oil phase from direct contact with the material surface. At the same time, the flexible molecular brush nanoparticles modified with amino groups through chemical bonding can dynamically capture, aggregate, and release oil at the oil-water interface, thereby significantly reducing the adhesion and accumulation of oil on the material surface.

[0010] This invention provides a method for preparing an underwater superoleophobic porous material with high oil resistance, comprising the following steps:

[0011] S1: Dissolve polyvinyl alcohol and tannic acid in a mixed solvent of deionized water and ethanol, and stir thoroughly until completely dissolved to obtain a polyvinyl alcohol / tannic acid mixed solution; wherein, the mass ratio of polyvinyl alcohol, tannic acid and mixed solvent is 1~10 : 1~10 : 100;

[0012] S2: Immerse the polyvinylidene fluoride porous membrane in the polyvinyl alcohol / tannic acid mixed solution obtained in step S1, sonicate for 1 minute, remove it, and dry it in an oven at 25°C until constant weight to obtain a pre-coated membrane.

[0013] S3: The pre-coated film obtained in step S2 is immersed in a 5 mmol / L FeCl3 aqueous solution for 30 minutes, then removed and dried in a 25°C oven to constant weight to obtain Fe... 3+ Crosslinked modified membrane;

[0014] S4: Mix 1-10 parts styrene, 1-10 parts divinylbenzene, 1-10 parts glycidyl methacrylate and 1-5 parts emulsifier by mass, and ultrasonically disperse to obtain a polymer oil phase; dissolve 0.1-1 parts initiator Na2S2O8 in 20 parts deionized water to obtain an initiator aqueous phase; pour the initiator aqueous phase into the polymer oil phase at once, and stir at 500-2000 r / min for 5 minutes; then add 80 parts anhydrous ethanol and continue stirring for 5 minutes; seal the mixture and react at 60-80℃ for 6-12 hours; after the reaction, centrifuge and wash the product 5 times with anhydrous ethanol to obtain polymer nanoparticles;

[0015] S5: Disperse 5 parts by weight of the polymer nanoparticles obtained in step S4 and 1-10 parts by weight of the amino polymer in 60 parts by weight of anhydrous ethanol, and react for 4 hours at 80°C and 500 r / min with stirring. After the reaction, wash the nanoparticles 5 times with anhydrous ethanol by centrifugation to obtain amino-modified nanoparticles. The amino polymer is one of polyethyleneimine, polyetheramine, and aminopropyl-terminated polydimethylsiloxane. The number average molecular weight of the amino polymer is 200-5000.

[0016] S6: Add 0.5-1 parts by weight of the amino-modified nanoparticles obtained in step S5 and 8 parts by weight of ammonia water to 400 parts by weight of deionized water, and ultrasonically disperse until uniform to obtain a nanoparticle dispersion; add the Fe obtained in step S3... 3+ The cross-linked modified membrane was immersed in the nanoparticle dispersion and reacted with shaking at 50°C for 6 hours. After the reaction was completed, the membrane was removed and washed with deionized water, and then dried to constant weight to obtain the underwater superoleophobic porous material with high oil resistance.

[0017] The volume ratio of deionized water to ethanol in the mixed solvent is 1:0.5~2.

[0018] Furthermore, the emulsifier is one of sodium dodecyl sulfate, sodium dodecylbenzene sulfonate, hexadecyltrimethylammonium bromide, Tween 80, Poroxam 127, and Span 80.

[0019] Compared with the prior art, the advantages of the present invention are:

[0020] The material prepared by this invention has a unique structural design and chemical composition, which not only gives it excellent underwater superoleophobic properties, but also exhibits significant high oil resistance. It can effectively resist oil contamination and structural damage during continuous oil-water separation, and is especially suitable for the efficient separation of oil-in-water emulsions.

[0021] During the separation process, the material is first pre-wetted with water to form a stable and dense hydration film on its surface hydrophilic layer, thereby physically blocking oil droplets at the oil-water-solid three-phase interface. Based on the synergistic mechanism of size sieving and wettability, oil droplets in the emulsion are selectively blocked from the material surface and pores. At the same time, chemically grafted amino-modified flexible molecular brush nanoparticles can dynamically capture, enrich and release oil droplets at the interface, effectively preventing oil droplets from accumulating and adhering locally, and ensuring the long-term unobstructed flow of the separation channel.

[0022] Based on the above characteristics, the porous material prepared by this invention can achieve continuous and efficient separation of surfactant-stabilized oil-in-water emulsions, and has important practical application prospects in the fields of oily wastewater treatment and marine oil spill recovery. Attached Figure Description

[0023] Figure 1 This is a scanning electron microscope image of the amino-modified nanoparticles prepared in Example 1. Figure 1 (a) and (a1) are SEM images of amino-modified nanoparticles at different magnifications.

[0024] Figure 2 These are scanning electron microscope images of the underwater superoleophobic porous material with high oil resistance prepared in Example 1, the porous materials prepared in Comparative Examples 1 and 2, and the polyvinylidene fluoride porous membrane. Figure 2 (a) and (a1), Figure 2 (b) and (b1), Figure 2 (c) and (c1) and Figure 2 (d) and (d1) are SEM images of the porous materials and polyvinylidene fluoride porous membranes of Example 1, Comparative Example 1, and Comparative Example 2 at different magnifications, respectively.

[0025] Figure 3 This refers to the wetting performance test of the underwater superoleophobic porous material with high oil resistance prepared in Example 1; wherein... Figure 3 (a) is a digital photograph and contact angle diagram of an underwater oil droplet on its surface. Figure 3 (b) is a diagram showing the dynamic contact angle of a water droplet in the air on its surface. Figure 3 (c) is a diagram showing the dynamic adhesion between oil droplets and their surface. Figure 3 (d) is a diagram showing the rolling angle of an oil droplet on its surface.

[0026] Figure 4 This is a diagram showing the testing process of the underwater superoleophobic porous material with high oil resistance prepared in Example 1 and the porous materials prepared in Comparative Examples 1 and 2 against crude oil. Figure 4 (a) is a process diagram of the antifouling process of the porous material prepared in Comparative Example 1. Figure 4(b) is a process diagram showing the antifouling process of the porous material prepared in Comparative Example 2. Figure 4 (c) is a process diagram of the antifouling process of the porous material prepared in Example 1.

[0027] Figure 5 This is a digital photograph showing the separation of SDS-stabilized water-in-toluene emulsions by the underwater superoleophobic porous material with high oil resistance prepared in Example 1 and the porous materials prepared in Comparative Examples 1 and 2. Figure 5 (a) is a process diagram, enlarged view, and diagram of the porous material after separation of water-in-toluene emulsion using porous materials in Example 1. Figure 5 (b) is a process diagram, enlarged view, and diagram of the porous material after separation of water-in-toluene emulsion using porous materials in Comparative Example 1. Figure 5 (c) is a process diagram, enlarged view, and diagram of the porous material after separation of water-in-toluene emulsion using the porous material in Comparative Example 2. Detailed Implementation

[0028] The preferred embodiments of the present invention will be described below with reference to the accompanying drawings. It should be understood that the preferred embodiments described herein are for illustration and explanation only, and do not constitute any limitation on the present invention.

[0029] Example 1: (1) Polyvinyl alcohol and tannic acid were dissolved in a mixed solvent of deionized water and ethanol, and stirred thoroughly until completely dissolved to obtain a polyvinyl alcohol / tannic acid mixed solution; wherein the mass ratio of polyvinyl alcohol, tannic acid and mixed solvent was 5:5:100; (2) Polyvinylidene fluoride porous membrane was immersed in the polyvinyl alcohol / tannic acid mixed solution obtained above, ultrasonically treated for 1 minute, taken out, and dried in an oven at 25°C to constant weight to obtain a pre-coated membrane; (3) The obtained pre-coated membrane was soaked in a 5 mmol / L FeCl3 aqueous solution for 30 minutes, taken out, and dried in an oven at 25°C to constant weight to obtain Fe 3+Crosslinked modified membrane; (4) Mix 15 parts styrene, 5 parts divinylbenzene, 5 parts glycidyl methacrylate and 10 parts Span80 by mass, and ultrasonically disperse them evenly to obtain a polymer oil phase; dissolve 2 parts initiator Na2S2O8 in 2000 parts deionized water to obtain an initiator aqueous phase; pour the initiator aqueous phase into the polymer oil phase at once, and stir and mix at 500 r / min for 5 minutes; then add 8000 parts anhydrous ethanol and continue stirring for 5 minutes; seal the mixture and react at 65°C for 8 hours; after the reaction, centrifuge and wash the product 5 times with anhydrous ethanol to obtain polymer nanoparticles; (5) disperse 5 parts by weight of the polymer nanoparticles and 7 parts by weight of aminopropyl-terminated polydimethylsiloxane in 60 parts anhydrous ethanol, and stir at 80°C and 500 r / min. The reaction was carried out for 4 hours under stirring at r / min; after the reaction, the nanoparticles were washed 5 times by centrifugation with anhydrous ethanol to obtain aminopropyl-terminated polydimethylsiloxane-modified nanoparticles; (6) 0.9 parts by weight of the aminopropyl-terminated polydimethylsiloxane-modified nanoparticles and 8 parts by weight of ammonia water were added to 400 parts by weight of deionized water and ultrasonically dispersed evenly to obtain an aminopropyl-terminated polydimethylsiloxane-modified nanoparticle dispersion; the Fe obtained in step (3) was added to the nanoparticles. 3+ The cross-linked modified membrane was immersed in the dispersion of aminopropyl-terminated polydimethylsiloxane-modified nanoparticles and reacted with shaking at 50°C for 6 hours. After the reaction was completed, the membrane was removed and washed with deionized water, and then dried to constant weight to obtain the underwater superoleophobic porous material with high oil resistance.

[0030] Example 2: (1) Polyvinyl alcohol and tannic acid were dissolved in a mixed solvent of deionized water and ethanol, and stirred thoroughly until completely dissolved to obtain a polyvinyl alcohol / tannic acid mixed solution; wherein the mass ratio of polyvinyl alcohol, tannic acid and mixed solvent was 5:5:100; (2) A polyvinylidene fluoride porous membrane was immersed in the polyvinyl alcohol / tannic acid mixed solution obtained above, ultrasonically treated for 1 minute, taken out, and dried in an oven at 25°C to constant weight to obtain a pre-coated membrane; (3) The obtained pre-coated membrane was soaked in a 5 mmol / L FeCl3 aqueous solution for 30 minutes, taken out, and dried in an oven at 25°C to constant weight to obtain a Fe 3+Crosslinked modified membrane; (4) Mix 15 parts styrene, 5 parts divinylbenzene, 5 parts glycidyl methacrylate and 10 parts Tween 80 by mass, and ultrasonically disperse them evenly to obtain a polymer oil phase; dissolve 2 parts initiator Na2S2O8 in 2000 parts deionized water to obtain an initiator aqueous phase; pour the initiator aqueous phase into the polymer oil phase at once, and stir and mix at 500 r / min for 5 minutes; then add 8000 parts anhydrous ethanol and continue stirring for 5 minutes; seal the mixture and react at 65°C for 8 hours; after the reaction, centrifuge and wash the product 5 times with anhydrous ethanol to obtain polymer nanoparticles; (5) disperse 5 parts by weight of the polymer nanoparticles and 7 parts by weight of polyethyleneimine in 60 parts anhydrous ethanol, and stir at 80°C and 500 r / min. The reaction was carried out for 4 hours under stirring at r / min; after the reaction was completed, the nanoparticles were washed 5 times by centrifugation with anhydrous ethanol to obtain polyethyleneimine-modified nanoparticles; (6) 0.9 parts by weight of the polyethyleneimine-modified nanoparticles and 8 parts by weight of ammonia water were added to 400 parts by weight of deionized water and ultrasonically dispersed evenly to obtain a dispersion of polyethyleneimine-modified nanoparticles; the Fe obtained in step (3) was added to the dispersion of polyethyleneimine-modified nanoparticles. 3+ The cross-linked modified membrane was immersed in the dispersion of polyethyleneimine-modified nanoparticles and reacted with shaking at 50°C for 6 hours. After the reaction was completed, the membrane was removed and washed with deionized water, and then dried to constant weight to obtain the underwater superoleophobic porous material with high oil resistance.

[0031] Example 3: (1) Polyvinyl alcohol and tannic acid were dissolved in a mixed solvent of deionized water and ethanol, and stirred thoroughly until completely dissolved to obtain a polyvinyl alcohol / tannic acid mixed solution; wherein the mass ratio of polyvinyl alcohol, tannic acid and mixed solvent was 5:5:100; (2) Polyvinylidene fluoride porous membrane was immersed in the polyvinyl alcohol / tannic acid mixed solution obtained above, ultrasonically treated for 1 minute, taken out, and dried in an oven at 25°C to constant weight to obtain a pre-coated membrane; (3) The obtained pre-coated membrane was soaked in a 5 mmol / L FeCl3 aqueous solution for 30 minutes, taken out, and dried in an oven at 25°C to constant weight to obtain Fe 3+Crosslinked modified membrane; (4) Mix 15 parts styrene, 5 parts divinylbenzene, 5 parts glycidyl methacrylate and 10 parts Tween 80 by mass, and ultrasonically disperse them evenly to obtain a polymer oil phase; dissolve 2 parts initiator Na2S2O8 in 2000 parts deionized water to obtain an initiator aqueous phase; pour the initiator aqueous phase into the polymer oil phase at once, and stir and mix at 500 r / min for 5 minutes; then add 8000 parts anhydrous ethanol and continue stirring for 5 minutes; seal the mixture and react at 65°C for 8 hours; after the reaction, centrifuge and wash the product 5 times with anhydrous ethanol to obtain polymer nanoparticles; (5) disperse 5 parts by weight of the polymer nanoparticles and 7 parts by weight of polyethyleneimine in 60 parts anhydrous ethanol, and stir at 80°C and 500 r / min. The reaction was carried out for 4 hours under stirring at r / min; after the reaction, the nanoparticles were washed 5 times by centrifugation with anhydrous ethanol to obtain polyethyleneimine-modified nanoparticles; (6) 0.8 parts by weight of the polyethyleneimine-modified nanoparticles and 8 parts by weight of ammonia water were added to 400 parts by weight of deionized water and ultrasonically dispersed to obtain a polyethyleneimine-modified nanoparticle dispersion; the Fe obtained in step (3) was added to the mixture. 3+ The cross-linked modified membrane was immersed in the dispersion of polyethyleneimine-modified nanoparticles and reacted with shaking at 50°C for 6 hours. After the reaction was completed, the membrane was removed and washed with deionized water, and then dried to constant weight to obtain the underwater superoleophobic porous material with high oil resistance.

[0032] Example 4: (1) Polyvinyl alcohol and tannic acid were dissolved in a mixed solvent of deionized water and ethanol, and stirred thoroughly until completely dissolved to obtain a polyvinyl alcohol / tannic acid mixed solution; wherein the mass ratio of polyvinyl alcohol, tannic acid and mixed solvent was 5:5:100; (2) Polyvinylidene fluoride porous membrane was immersed in the polyvinyl alcohol / tannic acid mixed solution obtained above, ultrasonically treated for 1 minute, taken out, and dried in an oven at 25°C to constant weight to obtain a pre-coated membrane; (3) The obtained pre-coated membrane was soaked in a 5 mmol / L FeCl3 aqueous solution for 30 minutes, taken out, and dried in an oven at 25°C to constant weight to obtain Fe 3+Crosslinked modified membrane; (4) Mix 15 parts styrene, 5 parts divinylbenzene, 5 parts glycidyl methacrylate and 10 parts sodium dodecyl sulfate by mass, and ultrasonically disperse evenly to obtain a polymer oil phase; dissolve 2 parts initiator Na2S2O8 in 2000 parts deionized water to obtain an initiator aqueous phase; pour the initiator aqueous phase into the polymer oil phase at once, and stir and mix at 500 r / min for 5 minutes; then add 8000 parts anhydrous ethanol and continue stirring for 5 minutes; seal the mixture and react at 65°C for 8 hours; after the reaction, centrifuge and wash the product 5 times with anhydrous ethanol to obtain polymer nanoparticles; (5) disperse 5 parts by weight of the polymer nanoparticles and 7 parts by weight of polyetheramine in 60 parts anhydrous ethanol, and stir at 80°C and 500 r / min. The reaction was carried out for 4 hours under stirring at r / min; after the reaction was completed, the nanoparticles were washed 5 times by centrifugation with anhydrous ethanol to obtain polyetheramine-modified nanoparticles; (6) 0.9 parts by weight of the polyetheramine-modified nanoparticles and 8 parts by weight of ammonia water were added to 400 parts by weight of deionized water and ultrasonically dispersed evenly to obtain a polyetheramine-modified nanoparticle dispersion; the Fe obtained in step (3) was added to the mixture. 3+ The cross-linked modified membrane was immersed in the dispersion of polyetheramine-modified nanoparticles and reacted with shaking at 50°C for 6 hours. After the reaction was completed, the membrane was removed and washed with deionized water, and then dried to constant weight to obtain the underwater superoleophobic porous material with high oil resistance.

[0033] Example 5: (1) Polyvinyl alcohol and tannic acid were dissolved in a mixed solvent of deionized water and ethanol, and stirred thoroughly until completely dissolved to obtain a polyvinyl alcohol / tannic acid mixed solution; wherein the mass ratio of polyvinyl alcohol, tannic acid and mixed solvent was 5:5:100; (2) A polyvinylidene fluoride porous membrane was immersed in the polyvinyl alcohol / tannic acid mixed solution obtained above, ultrasonically treated for 1 minute, taken out, and dried in an oven at 25°C to constant weight to obtain a pre-coated membrane; (3) The obtained pre-coated membrane was soaked in a 5 mmol / L FeCl3 aqueous solution for 30 minutes, taken out, and dried in an oven at 25°C to constant weight to obtain a Fe 3+Crosslinked modified membrane; (4) Mix 15 parts styrene, 5 parts divinylbenzene, 5 parts glycidyl methacrylate and 10 parts sodium dodecyl sulfate by mass, and ultrasonically disperse evenly to obtain a polymer oil phase; dissolve 2 parts initiator Na2S2O8 in 2000 parts deionized water to obtain an initiator aqueous phase; pour the initiator aqueous phase into the polymer oil phase at once, and stir and mix at 500 r / min for 5 minutes; then add 8000 parts anhydrous ethanol and continue stirring for 5 minutes; seal the mixture and react at 65°C for 8 hours; after the reaction, centrifuge and wash the product 5 times with anhydrous ethanol to obtain polymer nanoparticles; (5) disperse 5 parts by weight of the polymer nanoparticles and 7 parts by weight of polyetheramine in 60 parts anhydrous ethanol, and stir at 80°C and 500 r / min. The reaction was carried out for 4 hours under stirring at r / min; after the reaction was completed, the nanoparticles were washed 5 times by centrifugation with anhydrous ethanol to obtain polyetheramine-modified nanoparticles; (6) 0.8 parts by weight of the polyetheramine-modified nanoparticles and 8 parts by weight of ammonia water were added to 400 parts by weight of deionized water and ultrasonically dispersed evenly to obtain a polyetheramine-modified nanoparticle dispersion; the Fe obtained in step (3) was added to the mixture. 3+ The cross-linked modified membrane was immersed in the dispersion of polyetheramine-modified nanoparticles and reacted with shaking at 50°C for 6 hours. After the reaction was completed, the membrane was removed and washed with deionized water, and then dried to constant weight to obtain the underwater superoleophobic porous material with high oil resistance.

[0034] Comparative Example 1: (1) Polyvinyl alcohol and tannic acid were dissolved in a mixed solvent of deionized water and ethanol, and stirred thoroughly until completely dissolved to obtain a polyvinyl alcohol / tannic acid mixed solution; wherein the mass ratio of polyvinyl alcohol, tannic acid and mixed solvent was 5:5:100; (2) Polyvinylidene fluoride porous membrane was immersed in the polyvinyl alcohol / tannic acid mixed solution obtained in step (1), ultrasonically treated for 1 minute, taken out, and dried in an oven at 25°C until constant weight to obtain a pre-coated membrane; (3) The pre-coated membrane obtained in step (2) was soaked in a 5 mmol / L FeCl3 aqueous solution for 30 minutes, taken out, and dried in an oven at 25°C until constant weight to obtain Fe 3+ Crosslinked modified underwater superoleophobic porous materials.

[0035] Comparative Example 2: (1) Polyvinyl alcohol and tannic acid were dissolved in a mixed solvent of deionized water and ethanol, and stirred thoroughly until completely dissolved to obtain a polyvinyl alcohol / tannic acid mixed solution; wherein the mass ratio of polyvinyl alcohol, tannic acid and mixed solvent was 5:5:100; (2) A polyvinylidene fluoride porous membrane was immersed in the polyvinyl alcohol / tannic acid mixed solution obtained above, ultrasonically treated for 1 minute, taken out, and dried in an oven at 25°C to constant weight to obtain a pre-coated membrane; (3) The obtained pre-coated membrane was soaked in a 5 mmol / L FeCl3 aqueous solution for 30 minutes, taken out, and dried in an oven at 25°C to constant weight to obtain a Fe 3+ Crosslinked modified membrane; (4) Mix 15 parts styrene, 5 parts divinylbenzene, 5 parts glycidyl methacrylate and 10 parts Span80 by mass, and ultrasonically disperse them evenly to obtain a polymer oil phase; dissolve 2 parts initiator Na2S2O8 in 2000 parts deionized water to obtain an initiator aqueous phase; pour the initiator aqueous phase into the polymer oil phase at once, and stir and mix at 500 r / min for 5 minutes; then add 8000 parts anhydrous ethanol and continue stirring for 5 minutes; seal the mixture and react at 65°C for 8 hours; after the reaction, centrifuge and wash the product 5 times with anhydrous ethanol to obtain polymer nanoparticles; (5) disperse 5 parts by weight of the polymer nanoparticles and 7 parts by weight of 1,12-dodecaneamine in 60 parts anhydrous ethanol, and stir at 80°C and 500 r / min. The reaction was carried out for 4 hours under stirring at r / min; after the reaction, the nanoparticles were washed 5 times by centrifugation with anhydrous ethanol to obtain 1,12-dodecaneamine-modified nanoparticles; (6) 0.9 parts by weight of the 1,12-dodecaneamine-modified nanoparticles and 8 parts by weight of ammonia water were added to 400 parts by weight of deionized water and ultrasonically dispersed evenly to obtain a dispersion of 1,12-dodecaneamine-modified nanoparticles; the Fe obtained in step (3) was added to the dispersion of 1,12-dodecaneamine-modified nanoparticles. 3+ The cross-linked modified membrane was immersed in the dispersion of 1,12-dodecaneamine-modified nanoparticles and reacted with shaking at 50°C for 6 hours. After the reaction was completed, the membrane was removed and washed with deionized water, and then dried to constant weight to obtain the underwater superoleophobic porous material.

[0036] The preferred embodiments of the present invention will be described below with reference to the accompanying drawings. It should be understood that the preferred embodiments described herein are for illustration and explanation only and are not intended to limit the present invention.

[0037] The performance tests involved in the embodiments of this invention are performed using the following methods:

[0038] 1. Scanning electron microscope image (SEM)

[0039] Figure 1SEM images of the amino-modified nanoparticles prepared in Example 1 are shown. Morphology analysis of the samples was performed using an Apreo 2C scanning electron microscope at an accelerating voltage of 10.0 kV. The samples were sputter-coated with gold before testing to enhance their conductivity. Figure 1 (a) The low-magnification image shows that the prepared nanoparticles are uniformly distributed; Figure 1 (a1) The high-magnification image further shows that the average size of the nanoparticles is about 300 nm and they exhibit good monodispersity with no obvious aggregation.

[0040] Figure 2 Scanning electron microscope (SEM) images of the underwater superoleophobic porous material with high oil resistance prepared in Example 1, the porous materials of Comparative Examples 1 and 2, and the polyvinylidene fluoride (PVDF) porous membrane are shown. The morphology of all samples was analyzed using an Apreo 2C scanning electron microscope at an accelerating voltage of 10.0 kV, and all samples underwent gold sputtering before testing. Observations revealed that all materials have a large number of uniformly distributed pores. In contrast, the material obtained in Example 1 exhibits a finer and denser pore structure, and its framework surface is covered with richer rough features. These structural characteristics indicate that the material prepared in Example 1 is more conducive to the efficient separation of micro / nano-scale oil-water emulsions.

[0041] 2. Wetting performance test

[0042] Figure 3 The wetting properties of the underwater superoleophobic porous material with high oil resistance prepared in Example 1 were tested. Regarding the contact angle test, an OCA 25 tester from Dataphysics (Germany) was used to test the underwater oil contact angle, dynamic water contact angle in air, underwater oil dynamic adhesion, and underwater oil roll-off angle of the product obtained in Example 1. Figure 3 As shown in (a), the macroscopic wetting properties of chloroform were demonstrated by staining it with an oil-soluble pigment (Oil Red O) and its contact angle was tested. It can be seen that the underwater oleophobic angle of the product obtained in Example 1 is 161.7°, proving that the product has underwater superoleophobic properties; from Figure 3 (b) It can be seen that the surface water contact angle of the product obtained in Example 1 becomes 0° within 10 s in air, proving that the product has superhydrophilicity; from Figure 3 (c) It can be seen that when the syringe moves downward to bring the oil droplet into close contact with the product obtained in Example 1, and then moves upward to separate them, the oil droplet does not show obvious deformation, proving that the product has good resistance to underwater oil adhesion; from Figure 3 (d) It can be seen that the underwater oil rolling angle of the product obtained in Example 1 is 3.3°, which proves that the oil droplets can roll well on the surface of the product in water.

[0043] 3. Anti-fouling performance test

[0044] Figure 4 The diagram shows the process of testing the antifouling performance of the underwater superoleophobic porous material with high antifouling properties prepared in Example 1 and the porous materials prepared in Comparative Examples 1 and 2 against crude oil. The antifouling performance of the products obtained in Examples 1, 1, and 2 was tested. The specific testing method was as follows: the products obtained in Comparative Examples 1, 2, and 1 were pre-wetted with water, then immersed in crude oil (highly viscous oil) for 1 minute, and finally placed in water to release the crude oil from the surface of the products. The entire process is as follows. Figure 4 As shown; from Figure 4 (a) It can be seen that after the product obtained in Example 1 came into contact with the water surface for 1 second, crude oil began to be released rapidly from the surface. After being placed underwater, there was no obvious crude oil residue on the surface at 6 seconds and 10 seconds, and the water surface color changed significantly compared to 0 seconds; from Figure 4 (b) It can be seen that after the product obtained in Comparative Example 1 was placed underwater, the crude oil contracted and accumulated on its surface. After 173 s, the crude oil accumulated in a small area on its surface. Combined with the change in water color, this indicates that only a small amount of crude oil was released from the product surface. Figure 4 (c) It can be seen that after the product obtained in Comparative Example 2 came into contact with the water surface for 3 seconds, crude oil began to be released on the surface. After being placed underwater, a small amount of crude oil remained on the surface after 8 seconds, and there was still residue on the surface after 15 seconds. However, the color of the water surface changed significantly compared to 0 seconds. In summary, the product obtained in Example 1 has a better antifouling effect and better antifouling performance than the products obtained in Comparative Example 1 and Comparative Example 2.

[0045] 4. Test for separating oil-in-water emulsions

[0046] Figure 5 Digital photographs of the underwater superoleophobic porous material with high anti-oil properties prepared in Example 1 and the porous materials prepared in Comparative Examples 1 and 2 separating SDS-stable water-in-toluene emulsions; the products obtained in Example 1, Comparative Examples 1 and 2 were tested for separation of water-in-oil emulsions. The specific test methods were as follows: (1) Preparation of high-stability water-in-oil emulsion: under the condition of V water: V oil = 95: 2.5, 0.0001 g / L oil-soluble pigment (Oil Red O) was used to stain toluene, and then 0.005 g / L SDS surfactant was added. The mixture was ultrasonically stirred for 5 min to obtain an SDS-stable water-in-toluene emulsion; (2) Separation of high-stability water-in-oil emulsion: the upper part of the gravity separation device was filled with water-in-toluene emulsion, the porous material was placed at the connection position between the upper and lower parts, and the filtrate obtained by separation was collected in the lower part. The small tube was connected to the vacuum pump; the prepared porous materials were used to separate the water-in-toluene emulsion for 6 min under the assistance of the vacuum pump. Figure 5 As shown; from Figure 5As can be seen from (a), (b), and (c), after 6 minutes of separation, the products obtained in Example 1, Comparative Example 1, and Comparative Example 2 all yielded clear filtrates. Example 1 yielded the most filtrate, followed by Comparative Example 2, and then Comparative Example 1 yielded the least. Furthermore, the emulsion surface phenomena and the porous materials after separation differed. Figure 5 (a) It can be seen that the surface of the porous material after separation in Example 1 showed no obvious staining oil, and a thick oil layer appeared on the surface of the emulsion; from Figure 5 (b) It can be seen that the surface of the porous material after separation in Comparative Example 1 has obvious staining and oil contamination, while the surface of the emulsion shows no obvious signs of staining. Figure 5 (c) It can be seen that the porous material surface after separation in Comparative Example 2 has less staining oil, and a thinner oil layer appears on the surface of the emulsion. In summary, this shows that during the separation of oil-in-water emulsions, the products obtained in Comparative Examples 1 and 2 have oil contamination on their surfaces. Further separation will affect the separation throughput and efficiency, which is not conducive to the continuous separation of oil-in-water emulsions. In contrast, the product obtained in Example 1 is less susceptible to oil contamination. By capturing, aggregating, and releasing oil droplets in the emulsion, an oil layer is formed on the liquid surface, which is more conducive to the continuous separation of oil-in-water emulsions.

[0047] The above description is merely a preferred embodiment of the present invention and is not intended to limit the present invention in any way. Although the present invention has been disclosed above with reference to preferred embodiments, it is not intended to limit the present invention. Any person skilled in the art can make some modifications or alterations to the above-disclosed technical content to create equivalent embodiments without departing from the scope of the present invention. Any simple modifications, equivalent changes, and alterations made to the above embodiments based on the technical essence of the present invention without departing from the scope of the present invention shall still fall within the scope of the present invention.

Claims

1. A method for preparing an underwater superoleophobic porous material with high oil resistance, characterized in that, Includes the following steps: S1: Dissolve polyvinyl alcohol and tannic acid in a mixed solvent of deionized water and ethanol, and stir thoroughly until completely dissolved to obtain a polyvinyl alcohol / tannic acid mixed solution; wherein, the mass ratio of polyvinyl alcohol, tannic acid and mixed solvent is 1~10 : 1~10 : 100; S2: Immerse the polyvinylidene fluoride porous membrane in the polyvinyl alcohol / tannic acid mixed solution obtained in step S1, sonicate for 1 minute, remove it, and dry it in an oven at 25°C until constant weight to obtain a pre-coated membrane. S3: The pre-coated film obtained in step S2 is immersed in a 5 mmol / L FeCl3 aqueous solution for 30 minutes, then removed and dried in a 25°C oven to constant weight to obtain Fe... 3+ Crosslinked modified membrane; S4: Mix 1-10 parts styrene, 1-10 parts divinylbenzene, 1-10 parts glycidyl methacrylate and 1-5 parts emulsifier by mass, and ultrasonically disperse to obtain a polymer oil phase; dissolve 0.1-1 parts initiator Na2S2O8 in 20 parts deionized water to obtain an initiator aqueous phase; pour the initiator aqueous phase into the polymer oil phase at once, and stir and mix at 500-2000 r / min for 5 minutes; then add 80 parts anhydrous ethanol and continue stirring for 5 minutes; seal the mixture and react at 60-80℃ for 6-12 hours; after the reaction, wash the product five times by centrifugation with anhydrous ethanol to obtain polymer nanoparticles; S5: Disperse 5 parts by weight of the polymer nanoparticles obtained in step S4 and 1-10 parts by weight of the amino polymer in 60 parts by weight of anhydrous ethanol, and react for 4 hours at 80°C and 500 r / min with stirring. After the reaction, wash the nanoparticles 5 times with anhydrous ethanol by centrifugation to obtain amino-modified nanoparticles. The amino polymer is one of polyethyleneimine, polyetheramine, and aminopropyl-terminated polydimethylsiloxane. The number average molecular weight of the amino polymer is 200-5000. S6: Add 0.5-1 parts by weight of the amino-modified nanoparticles obtained in step S5 and 8 parts by weight of ammonia water to 400 parts by weight of deionized water, and ultrasonically disperse until uniform to obtain a nanoparticle dispersion; add the Fe obtained in step S3... 3+ The cross-linked modified membrane was immersed in the nanoparticle dispersion and reacted with shaking at 50°C for 6 hours. After the reaction was completed, the membrane was removed and washed with deionized water, and then dried to constant weight to obtain the underwater superoleophobic porous material with high oil resistance.

2. The preparation method according to claim 1, characterized in that, In step S1, the volume ratio of deionized water to ethanol in the mixed solvent is 1:0.5~2.

3. The preparation method according to claim 1, characterized in that, In step S4, the emulsifier is one of sodium dodecyl sulfate, sodium dodecylbenzene sulfonate, hexadecyltrimethylammonium bromide, Tween 80, Poroxam 127, and Span 80.

4. An underwater superoleophobic porous material with high oil resistance, characterized in that, It is prepared by the method described in any one of claims 1-3.

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