Preparation method of anti-adhesion super-lubricating coating for separation and recovery of high-viscosity oil-water system

Abstract

The present invention discloses a method for preparing an anti-adhesion super-lubricating coating for separation and recovery of high-viscosity oil-water systems, which is specifically as follows: a saturated carbon chain polymer, vinyl silicone oil, a cage-type mercapto compound, a siloxane compound and a photoinitiator are dissolved in an organic solvent, then mixed evenly, coated on a substrate, and cured using an ultraviolet lamp to obtain an anti-adhesion super-lubricating coating for separation and recovery of high-viscosity oil-water systems. The coating exhibits excellent anti-adhesion properties for various low-surface-tension organic solvents and even high-viscosity liquids such as crude oil and pump oil, can effectively prevent membrane contamination, and has excellent separation effects and long-term separation performance for various oil-water mixtures and high-viscosity oil-in-water emulsions, thereby realizing the recycling and reuse of high-viscosity oil products. The coating has excellent thermal stability, corrosion resistance and organic solvent resistance, has good bonding strength on various substrates, and can be modified on various substrates such as smooth glass surfaces, cotton fabrics and stainless steel mesh substrates. At the same time, the coating can be prepared using various methods such as drop coating, spin coating, spray coating, and dip coating, with simple processes, convenient operation and low cost.

Description

Technical Field

[0001] The present invention belongs to the field of novel polymer functional materials and polymer coatings, and particularly relates to a method for preparing an anti-adhesion super-lubricating coating for separation and recovery of high-viscosity oil-water systems. Background Art

[0002] Statistics show that 120 million gallons of crude oil and its refined products leak into the marine environment each year, causing significant marine pollution. Frequent oil spills not only cause catastrophic damage to marine ecosystems but also result in enormous energy waste. In line with modern society's green environmental protection and sustainable development concepts, the rapid, effective, and environmentally friendly cleanup of high-viscosity oil spills remains a global challenge.

[0003] At present, the traditional technologies for cleaning up oil spills include chemical treatment (dispersants, demulsifiers), in-situ combustion, physical / mechanical technology, bioremediation, etc. However, these traditional treatment methods have the disadvantages of easily causing secondary pollution due to the addition of chemical agents, serious energy consumption, high cost, and long time consumption. In recent years, the use of special wettability membrane materials to separate oil and water by the specific selectivity and filterability of oil and water has the advantages of simple separation method and recyclability, and is a very promising oil-water separation technology. Superhydrophobic and superoleophilic materials, as an existing new treatment technology, can achieve oil-water separation, but are easily contaminated by oil, and for anti-oil adhesion materials, they are usually superoleophobic and superhydrophobic and superhydrophilic / underwater superoleophobic materials, both of which cannot achieve the separation of viscous oil emulsions. Therefore, using a relatively simple method to prepare a stable, anti-adhesion superlubricating coating and applying it to the field of high-viscosity oil-water separation has become a problem to be solved urgently.

[0004] In order to solve the above problems, we have prepared an anti-adhesion super-lubricating coating for separation and recovery of high-viscosity oil-water systems, which can prevent membrane contamination and is used for long-term and efficient recovery of high-viscosity oil products. Specifically, saturated carbon chain polymers are interspersed in the cross-linked network generated by the chemical reaction of vinyl silicone oil and cage-type thiol compounds to form an interpenetrating polymer network structure, thereby achieving anti-adhesion performance for high-viscosity fluids. Due to chemical cross-linking, these molecular structures will not be dissolved or replaced by the organic solvents in contact, and they show excellent anti-adhesion performance for various low-surface-tension organic solvents and even high-viscosity liquids such as crude oil and pump oil, which can effectively prevent membrane contamination. At the same time, the coating is given good hydrophobic properties, and has excellent separation effects and long-term separation performance for various oil-water mixtures, improving the traditional super-hydrophobic lipophilic separation membrane that is easily adhered to oil products (especially high-viscosity oil products), thereby causing the super-hydrophobic performance to decrease and eventually lose the separation performance. On the other hand, it solves the problem that the coating prepared by existing commercial fluorine-containing materials can only prevent oil pollution but cannot achieve oil-water separation. In addition, the high degree of cross-linking in the coating gives it excellent thermal stability, corrosion resistance, and organic solvent resistance, greatly extending the service life of the coating. Saturated carbon chain polymers are used as adhesives to enhance the adhesion of the substrate, giving the coating a variety of substrate adaptability. It has good adhesion on various substrates and can be modified on smooth glass surfaces, cotton fabrics, stainless steel mesh substrates, and other substrates. The silicone compound is dispersed in the interpenetrating polymer network structure, improving its mechanical properties. More importantly, compared with existing super-oleophobic coatings, the coating we prepared can simultaneously achieve hydrophobicity and oleophilicity and prevent high-viscosity oils from adhering to the substrate surface, thereby achieving multiple recycling uses and improving the shortcomings of traditional super-hydrophobic membranes in long-term efficient separation and high-viscosity emulsion separation. The method is simple. It only needs to apply the prepared solution to the substrate and place it under ultraviolet light for curing to quickly prepare it in one step. It can be prepared by various methods such as drop coating, spin coating, spray coating, and dip coating. The process is simple, easy to operate, and low cost. Compared with commercial fluorine-containing material coatings, this coating exhibits better oil-water separation performance, thereby achieving viscous oil recovery performance. It is expected to be widely used in oil and gas pipeline transportation, lossless transportation, microfluidics, anti-fouling and self-cleaning, liquid collection, oil spill cleaning, sticky oil recovery, oil-water separation materials and other fields. It has great economic value and provides new ideas for the development of new superhydrophobic materials. Summary of the Invention

[0005] The purpose of the present invention is to provide a method for preparing an anti-adhesion super-lubricating coating for separation and recovery of high-viscosity oil-water systems, which is achieved by the following scheme:

[0006] (1) dissolving a saturated carbon chain polymer, vinyl silicone oil, a caged mercapto compound, a siloxane compound, and a photoinitiator in an organic solvent, then mixing them evenly and allowing them to stand for use;

[0007] (2) coating the mixed solution of step (1) on a clean substrate that has been cleaned and dried in advance;

[0008] (3) The coating in step (2) is placed under an ultraviolet lamp for light curing, and then taken out to obtain an anti-adhesion super-lubricating coating.

[0009] Furthermore, in the mixed solution described in step (1), the proportions of the saturated carbon chain polymer, vinyl silicone oil, cage-type mercapto compound, and siloxane compound are 3-30%, 30-50%, 10-42%, and 3-15%, respectively, and the rest are organic solvents.

[0010] Furthermore, the saturated carbon chain polymer described in step (1) is a linear saturated carbon chain polymer, including one or more of polyethylene, polypropylene, and polyvinyl chloride.

[0011] Furthermore, the substrate in step (2) is a glass, cotton fabric or stainless steel mesh substrate.

[0012] Furthermore, the caged mercapto compound in step (1) is a mercapto-functionalized polysilsesquioxane.

[0013] Furthermore, the light curing time in step (3) is 30 minutes.

[0014] Furthermore, the siloxane compound in step (1) is soft micro-nano particles with electrostatic adsorption function.

[0015] Furthermore, the photoinitiator in step (1) is a free radical initiator such as benzoin dimethyl ether.

[0016] Furthermore, the organic solvent in step (1) is one or more of halogenated hydrocarbons, aromatic hydrocarbons, saturated alcohols, and saturated esters.

[0017] Furthermore, the coating method in step (2) is any one of drop coating, spin coating, spray coating, and dip coating.

[0018] The advantages of the present invention are:

[0019] (1) Various coating methods such as drop coating, spin coating, spray coating, and dip coating can be used, with simple process, easy operation and low cost.

[0020] (2) The coating has a variety of substrate adaptability and good adhesion on various substrates. It can be modified on smooth glass surfaces, cotton fabrics, stainless steel mesh substrates and other substrates.

[0021] (3) The coating has hydrophobic properties, has excellent separation effects on various oil-water mixtures, and can be recycled multiple times.

[0022] (4) The coating exhibits excellent anti-adhesion properties to various low surface tension organic solvents and even high viscosity liquids such as crude oil and pump oil, which can effectively prevent membrane contamination.

[0023] (5) The coating has long-term separation performance, ensuring the long-term use of the coating in oil-water separation.

[0024] (6) The coating has excellent thermal stability, corrosion resistance and resistance to organic solvents. BRIEF DESCRIPTION OF THE DRAWINGS

[0025] Figure 1 The thermogravimetric analysis graph and differential thermogravimetric analysis graph of the coatings prepared in Example 1 and Comparative Example 1 are shown.

[0026] Figure 2 The atomic force microscope test of the coatings prepared in Example 1, Comparative Example 1 and Comparative Example 2 is shown.

[0027] Figure 3 The graph shows the changes in the contact angles of water and oil and the sliding angles of the coatings prepared in Example 1, Comparative Example 1 and Comparative Example 3 after being immersed in a strong corrosive solution and an organic solvent for 15 hours.

[0028] Figure 4 The separation flux of oil-water mixture modified by coating on cotton fabric and the separation efficiency after multiple recycling are shown.

[0029] Figure 5 The figure shows the residual conditions of perfluorosilane, coatings prepared from any of Examples 1-3 and commercial fluorine-containing materials on a stainless steel mesh after filtration of crude oil and pump oil.

[0030] Figure 6 The results show the performance of the coating modifications prepared in Example 1, Comparative Example 1 and Comparative Example 3 in separating water-in-hexadecane emulsion on a stainless steel mesh.

[0031] Figure 7 The separation performance of the coating for emulsions of different viscosities is shown, including separation flux, separation efficiency, separation flux decrease rate (RFD) and transmittance before and after separation. DETAILED DESCRIPTION

[0032] The present invention will be described in further detail below with reference to examples and drawings, but the embodiments of the present invention are not limited thereto.

[0033] Prepare the coating mixed solution according to the proportions in Table 1

[0034] Table 1 Proportions of coating mixed solution

[0035]

[0036]

[0037] The saturated carbon chain polymer in Example 1 is polyethylene, and the photoinitiator is benzoin dimethyl ether. The saturated carbon chain polymer in Example 2 is polypropylene, and the photoinitiator is benzoin dimethyl ether. The saturated carbon chain polymer in Example 3 is polyvinyl chloride, and the photoinitiator is benzoin dimethyl ether. The saturated carbon chain polymers used in Comparative Examples 1, 2, and 3 are all polyethylene, and the photoinitiator is benzoin dimethyl ether.

[0038] Methanol, concentrated hydrochloric acid and mercaptosilane are first added to a three-necked flask, reacted for 24 hours, and obtained after separation and purification, a cage-type mercapto compound. Polysiloxane, aminopropyl triethoxysilane are then dissolved in ethyl acetate and an ethanol solution, and 80 DEG C of standing conditions for 3 days give siloxane compounds. Next, glass, cotton fabric or stainless steel mesh and other substrates are sequentially ultrasonically cleaned for 30 minutes using acetone, anhydrous ethanol and deionized water, and then placed in an oven for 60 DEG C of drying after the completion of the ultrasound. Saturated carbon chain polymers, vinyl silicone oils, cage-type mercapto compounds, siloxane compounds, and photoinitiators are mixed according to the ratio of each of the above embodiments, dissolved in an organic solvent, toluene, and then uniformly mixed by ultrasonic 2h. The mixed solution is applied to glass, cotton fabric or stainless steel mesh substrates cleaned and dried in advance using a spin coating method, placed under an ultraviolet lamp (365nm) for light curing, and after 30 minutes, a film is formed to obtain an anti-adhesion super-lubricating coating for separating and recycling a high-viscosity oil-water system.

[0039] The following are the items tested for the characteristics of the coatings of each embodiment on different substrates:

[0040] Test 1: Thermal stability test of different coatings

[0041] The coatings prepared in Example 1 and Comparative Example 1 were subjected to thermogravimetric analysis and differential thermogravimetric analysis. Figure 1 As shown, the coating of Comparative Example 1 experienced the greatest weight loss at 400°C and completely decomposed at 440°C, while the coating of Example 1 experienced the greatest weight loss at 432°C. When the temperature was raised to 800°C, 15.5% of the coating remained. This indicates that the coating contains a cross-linked structure that imparts excellent thermal stability to the coating.

[0042] Test 2: 3D image characterization of different coatings

[0043] The coatings prepared in Example 1, Comparative Example 1 and Comparative Example 2 were characterized by atomic force microscopy. Figure 2As shown in (a), the surface of the coating of Comparative Example 1 is very smooth, with a roughness of only 0.352nm, and the maximum height difference of the cross-section of the coating is only 1.35nm. After adding the low surface energy component of the cross-linked network structure and the mercapto compound component, the roughness of the coating of Comparative Example 2 increases to 1.93nm, and the maximum height difference of the coating increases to 6.31nm. When the micro-nano particle siloxane compound with electrostatic adsorption function is further added, the roughness of the coating of Example 1 increases to 65.9nm, and the surface height difference increases to 70.5nm. Further comparison of the phase diagrams of the three coatings, as shown in FIG. Figure 2 As shown in (b), the coatings of Comparative Example 1 and Comparative Example 2 are both continuous phases, while the surface of the coating of Example 1 contains bright brown particles, indicating that the micro-nanoparticles are uniformly dispersed in the cross-linked network.

[0044] Test 3: Corrosion resistance and organic solvent resistance

[0045] The coatings prepared in Example 1, Comparative Example 1 and Comparative Example 3 were modified on glass substrates. After the three coatings were immersed in corrosive solutions such as strong acid and strong base solutions, 1M NaCl solution and various organic solvents for 15 hours, the changes in the water contact angle and oil contact angle of the coating surfaces were compared. Figure 3 As shown, the coating of comparative example 1 and comparative example 3 still maintains hydrophobicity in the surface of corrosive solution soaking 15h, indicating that it has corrosion resistance. But after soaking in organic solvent toluene, the surface coating disappears, and is not resistant to organic solvents. On this basis, chemical crosslinking structure components vinyl silicone oil and cage-type thiol compound are introduced, and the crosslinked network generated by the chemical reaction further enhances the corrosion resistance of the coating while achieving organic solvent resistance. After soaking in highly corrosive solution and various organic reagents, the coating of embodiment 1 can still maintain hydrophobicity and oil-proof adhesion performance, and the sliding angle of oil is still very low. Show that the addition of saturated carbon chain polymer can not only increase the affinity of coating and substrate, but also can synergize with the crosslinked network structure, as double protection, giving coating excellent corrosion resistance and organic solvent resistance.

[0046] Test 4: Coating oil-water separation performance and recycling performance

[0047] Any cotton fabric substrate coated with the coating of Examples 1-3 can achieve super hydrophobicity of the cotton fabric, with a surface contact angle of about 151°, and can be applied to the separation of ordinary oil-water mixtures with excellent separation effects. Figure 4 As shown in the figure, a customized three-way separation device is used to separate different oil-water mixtures. Due to its super-hydrophobic properties, it has excellent separation effects on various oil-water mixtures, and the separation flux of each oil-water mixture is greater than 5000Lm -2 h -1, and the coating can still maintain a separation efficiency of over 95% after multiple cycles. This shows that the coating has a variety of substrate adaptability and can be modified on smooth glass surfaces as well as porous substrates such as cotton fabric and stainless steel mesh. More importantly, the coating has oil-water separation performance and recyclability, which shows that the coating has excellent anti-adhesion properties and can be reused multiple times.

[0048] Test 5: Coating anti-fouling performance

[0049] For perfluorosilane, the coating prepared from Examples 1-3 and commercial PVDF hydrophobic material was randomly selected and modified on a stainless steel mesh. Then, various filter membranes were placed on a sand core, and 15 microliters of oil droplets (97.5 Cp of pump oil and 432.5 Cp of crude oil) were dropped. The residue of the oil droplets on the surface of different filter membranes was observed by suction filtration. Figure 5 As shown, due to its oleophobic nature, the perfluorosilane-coated steel mesh repels oil droplets, making it difficult for pump oil to be filtered out. However, the pump oil immediately seeps down the surface of the prepared coating, leaving no residual oil droplets. In contrast, the commercially available PVDF hydrophobic filter membrane, which is hydrophobic and oleophilic, immediately wets the membrane surface and penetrates downward. However, the membrane surface is contaminated by the pump oil, leaving oil stains. Prolonged use inevitably degrades the membrane's performance. Similarly, crude oil has difficulty penetrating the perfluorosilane-modified stainless steel mesh and ultimately leaves traces of crude oil. Due to its high viscosity, crude oil cannot even penetrate the PVDF membrane surface. However, high-viscosity crude oil can quickly penetrate the prepared coating surface, leaving only very small traces. These results demonstrate that the prepared coating exhibits excellent membrane-fouling resistance and can be applied in oil-water separation applications to address membrane fouling issues and ensure the long-term usability of the coating.

[0050] Test 6: Coating performance on separation of water-in-hexadecane emulsion

[0051] The coatings prepared in Example 1, Comparative Example 1 and Comparative Example 3 were modified on a stainless steel mesh to test the performance of the coatings in separating water-in-hexadecane emulsion. Figure 6 As shown, due to screening and hydrophobic effects, the coating of Comparative Example 1 has an emulsion separation effect in the first 20 minutes of filtration, but gradually loses separation performance after 20 minutes. After 3 hours, the filtrate is as turbid as the initial emulsion. This may be due to the long-term oil contact with the coating surface, which causes its hydrophobic performance to decrease, and ultimately causes the coating to lose its filtration performance. The coating of Comparative Example 3 also has the same effect, and its separation efficiency and flux both decrease very quickly due to membrane contamination. However, the coating of Example 1 can prevent membrane contamination because it contains excellent anti-adhesion properties and hydrophobic properties. After 3 hours of continuous emulsion separation, the final water content is only about 41.5ppm, still having excellent separation effect.

[0052] Test 7: Long-term separation performance of coating for different emulsions

[0053] The coatings prepared in Examples 1-3 were randomly selected and applied to a stainless steel mesh to test the separation performance of the coatings for emulsions of different viscosities. Figure 7 As shown, the coating exhibits excellent separation performance for kerosene-in-water emulsions, soybean oil-in-water emulsions, and high-viscosity pump oil-in-water emulsions, maintaining high separation efficiency even after 3 hours of continuous separation. The coating's ability to separate emulsions of varying viscosities for extended periods, with high separation flux maintained even after 3 hours, is attributed to the coating's excellent anti-adhesion properties. This improves the problem of traditional filtration membranes, which can severely reduce flux and separation efficiency due to membrane fouling, and has significant potential for application in the field of filtration and separation.

[0054] Therefore, the anti-adhesion super-lubricating coating for separation and recovery of high-viscosity oil-water systems prepared by the present invention is interspersed with saturated carbon chain polymers in the cross-linked network generated by the chemical reaction of vinyl silicone oil and cage-type thiol compounds to form an interpenetrating polymer network structure, thereby achieving anti-adhesion performance for high-viscosity fluids, effectively preventing membrane contamination, and at the same time giving the coating good separation performance, with excellent separation effect and long-term separation performance for various oil-water mixtures and even high-viscosity emulsions, thereby achieving the recycling and reuse of high-viscosity oil products. In addition, the saturated carbon chain polymer is used as an adhesive to enhance the bonding ability of the substrate, so that the coating has a variety of substrate adaptability, and the siloxane compound is dispersed in the interpenetrating polymer network structure, thereby improving its mechanical properties. More importantly, the higher degree of cross-linking gives the coating excellent thermal stability, corrosion resistance and organic solvent resistance, greatly extending the service life of the coating.

[0055] It should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention and are not intended to limit the present invention. Although the present invention has been described in detail with reference to preferred embodiments, those skilled in the art should understand that several improvements and modifications may be made without departing from the principles of the present invention, and all of these improvements and modifications should be included within the scope of the claims of the present invention.

Claims

1. A method for preparing an anti-adhesion super-lubricating coating for separation and recovery of high-viscosity oil-water systems, characterized in that: The method comprises the following steps: (1) Dissolve a saturated carbon chain polymer, vinyl silicone oil, caged mercapto compound, siloxane compound and photoinitiator in an organic solvent, then mix them evenly and let them stand for use; (2) coating the mixed solution of step (1) on a clean substrate that has been cleaned and dried in advance; (3) The coating in step (2) is placed under a UV lamp for light curing, and then taken out to obtain an anti-adhesion super-lubricating coating; The saturated carbon chain polymer is a linear saturated carbon chain polymer, including one or more of polyethylene, polypropylene, and polyvinyl chloride; The caged thiol compound is a thiol-functionalized polysilsesquioxane; The silicone compound is soft micro-nano particles with electrostatic adsorption function.

2. The method according to claim 1, characterized in that The substrate in step (2) is a glass, cotton fabric or stainless steel mesh substrate.

3. The method according to claim 1, characterized in that The light curing time is 30 minutes.

4. The method according to claim 1, wherein The photoinitiator is a free radical initiator, including benzoin dimethyl ether.

5. The method according to claim 1, wherein The organic solvent is one or more of halogenated hydrocarbons, aromatic hydrocarbons, saturated alcohols and saturated esters.

6. The method according to claim 1, characterized in that The coating method is any one of drop coating, spin coating, spray coating, and dip coating.

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