阅读说明：本技术 面向油水分离可切换表面润湿性能的涂层及其制备方法 (Coating capable of switching surface wettability for oil-water separation and preparation method thereof ) 是由 廖景文 陈勃旭 杨明瑾 林锡霖 袁海 于 2020-12-01 设计创作，主要内容包括：本发明涉及油水分离技术领域,具体涉及一种面向油水分离可切换表面润湿性能的涂层及其制备方法。可切换表面润湿性能的涂层包括低表面能化学相、多层级拓扑物理相和附着剂；低表面能化学相包括极性基团氟聚合物和第一溶剂；多层级拓扑物理相包括无机微米颗粒、无机纳米颗粒和第二溶剂；低表面能化学相与多层级拓扑物理相的体积比为10：3～10。涂层的制备方法为将低表面能化学相、多层级拓扑物理相、附着剂混合密封静置排泡后,均匀涂覆于金属筛网,自然干燥,即得。本发明制备的涂层具有超亲水-超疏油表面,具有更高油水分离效率,在遇到酸性环境后,从超亲水-超疏油表面自由切换至超疏水-超疏油表面,具有抗酸性物质腐蚀性能。(The invention relates to the technical field of oil-water separation, in particular to a coating capable of switching surface wettability for oil-water separation and a preparation method thereof. The coating with switchable surface wettability properties comprises a low surface energy chemical phase, a multi-level topological physical phase and an adhesive; the low surface energy chemical phase includes a polar group fluoropolymer and a first solvent; the multi-level topological physical phase comprises inorganic microparticles, inorganic nanoparticles and a second solvent; the volume ratio of the low surface energy chemical phase to the multilevel topological physical phase is 10: 3 to 10. The preparation method of the coating comprises the steps of mixing, sealing, standing and discharging bubbles of the low-surface-energy chemical phase, the multi-level topological physical phase and the adhesive, uniformly coating the mixture on a metal screen, and naturally drying the metal screen to obtain the coating. The coating prepared by the method has a super-hydrophilic-super-oleophobic surface, has higher oil-water separation efficiency, can be freely switched from the super-hydrophilic-super-oleophobic surface to the super-hydrophobic-super-oleophobic surface after meeting an acidic environment, and has acid substance corrosion resistance.)

1. The coating facing the oil-water separation switchable surface wettability is characterized by comprising a low surface energy chemical phase, a multilevel topological physical phase and an adhesive; the low surface energy chemical phase includes a polar group fluoropolymer and a first solvent; the multi-level topological physical phase comprises inorganic microparticles, inorganic nanoparticles, and a second solvent; the volume ratio of the low surface energy chemical phase to the multilevel topological physical phase is 10: 3 to 10.

2. The coating facing switchable surface wetting performance of claim 1, wherein the adhesive is one of an aqueous solution of polyvinyl alcohol, an aqueous solution of polyvinyl pyrrolidone, an aqueous solution of polyethylene glycol, and sodium carboxymethylcellulose; the volume ratio of the adhesive to the total volume of the two phases of the low surface energy chemical phase and the multilevel topological physical phase is 3-15%: 1.

3. the coating of claim 1, wherein the polar group fluoropolymer is one or two of Zonyl 9361, Zonyl 7910, Zonyl FSA, Zonyl FSE, Capscone FS-64, Capscone FS-61, FPOSS-COOH, and FPOSS-NH.

4. The coating of claim 1, wherein the first solvent is one of water, ethanol, ethylene glycol, and isopropyl alcohol.

5. The coating facing switchable surface wetting performance of claim 1, wherein the inorganic microparticles are one of silica microparticles, titania microparticles, zirconia microparticles, and alumina microparticles; the inorganic nano-particles are one of silicon dioxide nano-particles, titanium dioxide nano-particles, zinc oxide nano-particles and aluminum oxide nano-particles.

6. The coating of claim 1, wherein the second solvent is one of ethanol, isopropanol, dipropylene glycol methyl ether, and dipropylene glycol butyl ether.

7. The coating of claim 1, wherein the inorganic microparticles to inorganic nanoparticles mass ratio is 10: 7 to 20.

8. The preparation method of the coating facing the wettability of the oil-water separation switchable surface, which is described in any one of claims 1 to 7, is characterized by comprising the following steps:

(1) uniformly stirring and mixing the polar group fluoropolymer and a first solvent to form a low surface energy chemical phase;

(2) ultrasonically mixing inorganic microparticles, inorganic nanoparticles and a second solvent to form a multi-level topological physical phase;

(3) mixing the formed low surface energy chemical phase with the multi-level topological physical phase, adding an adhesive, sealing, standing and discharging bubbles to form slurry;

(4) and (4) uniformly coating the slurry prepared in the step (3) on a metal screen, and naturally drying to obtain the composite material.

9. The preparation method of the coating facing the oil-water separation switchable surface wettability property of claim 8, wherein the sealing standing time is 1-5 h.

10. The method for preparing the coating facing the wettability of the oil-water separation switchable surface, according to claim 8, wherein the coating is one of spray coating, dip coating, spin coating and blade coating.

Technical Field

The invention relates to the technical field of oil-water separation, in particular to a coating capable of switching surface wettability for oil-water separation and a preparation method thereof.

Background

With the rapid development of world industrialization, a large amount of oily wastewater is discharged from industries such as petrochemical industry, food, textile, metal processing and the like, and oil spilling events which frequently occur internationally also pollute coastal lands and marine environments and seriously harm natural environments and human survival. Conventional oil-water separation techniques include gravity separation, centrifugal separation, ultrasonic separation, air-float process, electric field process, coagulation process, chemical adsorption process, biodegradation process, membrane separation process, and the like. The membrane separation technology has the advantages of low energy consumption, easy operation, good separation effect and the like, and is widely concerned by researchers.

Hui Liu (Chemical Engineering Journal,2017, DOI:10.1016/j.cej.2017.07.114) sprays polysiloxane/polymethyl methacrylate on a metal screen to form a wear-resistant super-hydrophobic-super-oleophilic surface, which has excellent separation effect on oil-water mixture or emulsion. However, the super-hydrophobic-super-oleophilic surface prepared by the method is easily polluted by oily substances, and when oil and water are separated, the lower-layer high-density water can prevent the upper-layer low-density oil from contacting the separation membrane, so that the oil and water separation efficiency is not ideal. In addition, acidic substances such as inorganic acids and organic acids tend to corrode metal screens, and the effect of oil-water separation is seriously reduced. Compared with a super-hydrophobic-super-oleophylic surface, the super-hydrophilic-super-oleophobic surface with the metal screen as the substrate has higher oil-water separation efficiency.

Therefore, the super-hydrophilic-super-oleophobic coating capable of switching the surface wettability facing the oil-water separation is of great significance.

Disclosure of Invention

In view of the above, there is a need to provide a coating capable of switching surface wettability for oil-water separation, which can be freely switched from superhydrophilic-superoleophobic to superhydrophobic-superoleophobic, thereby inhibiting the permeation corrosion of acidic substances and improving the oil-water separation efficiency, and a preparation method thereof.

In order to achieve the purpose, the invention adopts the following technical scheme:

a coating facing oil-water separation switchable surface wettability properties comprises a low surface energy chemical phase, a multilevel topological physical phase and an adhesive; the low surface energy chemical phase includes a polar group fluoropolymer and a first solvent; the multi-level topological physical phase comprises inorganic microparticles, inorganic nanoparticles, and a second solvent; the volume ratio of the low surface energy chemical phase to the multilevel topological physical phase is 10: 3 to 10.

Furthermore, in the coating facing the oil-water separation switchable surface wettability, the adhesive is one of a polyvinyl alcohol aqueous solution, a polyvinyl alcohol pyrrolidone aqueous solution, a polyethylene glycol aqueous solution and sodium carboxymethylcellulose; the volume ratio of the adhesive to the total volume of the two phases of the low surface energy chemical phase and the multilevel topological physical phase is 3-15%: 1.

preferably, in the coating facing the oil-water separation switchable surface wettability, the solid content of the polar group fluoropolymer in the low surface energy chemical phase is 2-10%.

Preferably, in the coating facing the oil-water separation switchable surface wettability, the solid content of inorganic micro-particles and inorganic nano-particles in the multi-level topological physical phase is 1-7%.

Preferably, in the coating facing the oil-water separation switchable surface wettability, the solid content of the adhesive is 0.5-4.5%.

Further, in the above coating layer for switching the wettability of the surface to oil/water separation, the polar group fluoropolymer is one or two of Zonyl 9361, Zonyl 7910, Zonyl FSA, Zonyl FSE, Capscone FS-64, Capscone FS-61, FPOSS-COOH and FPOSS-NH.

Further, in the coating facing the wettability of the oil-water separation switchable surface, the first solvent is one of water, ethanol, ethylene glycol and isopropanol.

Further, in the coating facing the oil-water separation switchable surface wettability, the inorganic microparticle is one of a silicon dioxide microparticle, a titanium dioxide microparticle, a zirconium dioxide microparticle and an aluminum oxide microparticle; the inorganic nano-particles are one of silicon dioxide nano-particles, titanium dioxide nano-particles, zinc oxide nano-particles and aluminum oxide nano-particles.

Preferably, in the coating facing the wettability of the oil-water separation switchable surface, the size of the inorganic micron particles is 1.5-9 μm.

Preferably, in the coating facing the oil-water separation switchable surface wettability, the size of the inorganic nanoparticles is 10-90 nm.

Further, in the coating layer facing the oil-water separation switchable surface wettability, the second solvent is one of ethanol, isopropanol, dipropylene glycol methyl ether and dipropylene glycol butyl ether.

Further, in the coating facing the wettability of the oil-water separation switchable surface, the mass ratio of the inorganic microparticles to the inorganic nanoparticles is 10: 7 to 20.

A preparation method of a coating facing oil-water separation switchable surface wettability performance comprises the following steps:

(1) uniformly stirring and mixing the polar group fluoropolymer and a first solvent to form a low surface energy chemical phase;

(2) ultrasonically mixing inorganic microparticles, inorganic nanoparticles and a second solvent to form a multi-level topological physical phase;

(3) mixing the formed low surface energy chemical phase with the multi-level topological physical phase, adding an adhesive, sealing, standing and discharging bubbles to form slurry;

(4) and (4) uniformly coating the slurry prepared in the step (3) on a metal screen, and naturally drying to obtain the composite material.

Further, in the preparation method of the coating facing the oil-water separation switchable surface wettability, the sealing and standing time is 1-5 hours.

Further, in the preparation method of the coating facing the oil-water separation switchable surface wettability, the coating mode is one of spray coating, dip coating, spin coating and blade coating.

Further, in the preparation method of the coating facing the oil-water separation switchable surface wettability, the metal screen is one of a stainless steel screen, a titanium screen, a copper screen, an aluminum screen and an iron screen.

Further, in the preparation method of the coating facing the oil-water separation switchable surface wettability, the mesh size of the metal screen is 120-800 meshes.

The invention has the beneficial effects that:

(1) the coating with switchable surface wettability provided by the invention comprises a low-surface-energy chemical phase based on a polar group fluoropolymer and a multi-level topological physical phase based on inorganic micro-particles/inorganic nano-particles, and the prepared coating has a super hydrophilic-super oleophobic surface and higher oil-water separation efficiency.

(2) The coating with switchable surface wettability can sense environmental acidity, is freely switched from the super-hydrophilic-super-oleophobic surface to the super-hydrophobic-super-oleophobic surface after meeting an acidic environment, inhibits the penetration of acidic substances, and has acid substance corrosion resistance.

(3) The coating with switchable surface wettability provided by the invention is simple in preparation process, can be cured by adopting a natural drying mode, is more convenient and easy to operate compared with processes such as ultraviolet curing, high-temperature curing and the like in the prior art, and can be constructed in a large area.

Drawings

FIG. 1 is an SEM image of a superhydrophilic-superoleophobic surface made according to example 1 of the invention;

FIG. 2 is a diagram showing the contact state of the coating prepared in example 1 with water and oil;

fig. 3 is an elemental analysis spectrum of the screens of example 1 and comparative example 1.

Detailed Description

In order to make the objects, technical solutions and advantages of the present invention clearer, the technical solutions of the present invention will be further clearly and completely described below with reference to the embodiments of the present invention. It should be noted that the described embodiments are only a part of the embodiments of the present invention, and not all embodiments. All other embodiments, which can be derived by a person skilled in the art from the embodiments given herein without making any creative effort, shall fall within the protection scope of the present invention.

Example 1

A coating facing oil-water separation switchable surface wettability properties comprises a low surface energy chemical phase, a multilevel topological physical phase and an adhesive; the low surface energy chemical phase includes a polar group fluoropolymer and a first solvent; the multi-level topological physical phase comprises inorganic microparticles, inorganic nanoparticles, and a second solvent; the volume ratio of the low surface energy chemical phase to the multilevel topological physical phase is 10: 4;

wherein the polar group fluoropolymer is Zonyl 9361, the first solvent is water, and the solid content of Zonyl 9361 in the low surface energy chemical phase is 3.5%;

wherein the inorganic microparticles are silica microparticles with the particle size of 4 μm, the inorganic nanoparticles are titanium dioxide nanoparticles with the particle size of 20nm, and the mass ratio of the silica microparticles to the titanium dioxide nanoparticles is 10: 13; the second solvent is ethanol; the total solid content of the silicon dioxide microparticles and the titanium dioxide nanoparticles in the multi-level topological physical phase is 3 percent;

wherein the adhesive is polyvinyl alcohol aqueous solution with solid content of 1.3%, and the volume of the adhesive is 5% of the total volume of the low surface energy chemical phase and the multi-level topological physical phase.

The coating facing the oil-water separation switchable surface wettability is prepared by the following method:

(1) mixing Zonyl 9361 with water to form a low surface energy chemical phase;

(2) ultrasonically mixing silicon dioxide micro-particles, titanium dioxide nano-particles and ethanol to form a multi-level topological physical phase;

(3) mixing the formed low surface energy chemical phase with the multi-level topological physical phase, adding a polyvinyl alcohol aqueous solution, sealing and standing for 1h, and discharging bubbles to form slurry;

(4) and (4) uniformly spraying the slurry prepared in the step (3) on a 200-mesh titanium screen, and naturally drying to obtain the titanium-based composite material.

Example 2

A coating facing oil-water separation switchable surface wettability properties comprises a low surface energy chemical phase, a multilevel topological physical phase and an adhesive; the low surface energy chemical phase includes a polar group fluoropolymer and a first solvent; the multi-level topological physical phase comprises inorganic microparticles, inorganic nanoparticles, and a second solvent; the volume ratio of the low surface energy chemical phase to the multilevel topological physical phase is 10: 7;

wherein the polar group fluoropolymer is Capstone FS-64, the first solvent is ethylene glycol, and the solid content of the Capstone FS-64 in the low surface energy chemical phase is 5%;

wherein the inorganic microparticles are silica microparticles of 5 μm, the inorganic nanoparticles are zinc oxide nanoparticles of 30nm, and the mass ratio of the silica microparticles to the zinc oxide nanoparticles is 10: 9; the second solvent is dipropylene glycol butyl ether; the total solid content of the silicon dioxide microparticles and the titanium dioxide nanoparticles in the multi-level topological physical phase is 3 percent;

wherein the adhesive is polyvinyl alcohol aqueous solution with solid content of 2%, and the volume of the adhesive is 5% of the total volume of the low surface energy chemical phase and the multi-level topological physical phase.

The coating facing the oil-water separation switchable surface wettability is prepared by the following method:

(1) uniformly stirring and mixing the Capstone FS-64 and ethylene glycol to form a low-surface-energy chemical phase;

(2) ultrasonically mixing silicon dioxide micron particles, zinc oxide nano particles and dipropylene glycol butyl ether to form a multi-level topological physical phase;

(3) mixing the formed low surface energy chemical phase with the multi-level topological physical phase, adding a polyvinyl alcohol aqueous solution, sealing and standing for 2 hours, and discharging bubbles to form slurry;

(4) and (4) uniformly spraying the slurry prepared in the step (3) on a stainless steel screen with 300 meshes, and naturally drying to obtain the coating.

Example 3

A coating facing oil-water separation switchable surface wettability properties comprises a low surface energy chemical phase, a multilevel topological physical phase and an adhesive; the low surface energy chemical phase includes a polar group fluoropolymer and a first solvent; the multi-level topological physical phase comprises inorganic microparticles, inorganic nanoparticles, and a second solvent; the volume ratio of the low surface energy chemical phase to the multilevel topological physical phase is 1: 1;

wherein the polar group fluoropolymer is Zonyl FSA, the first solvent is isopropanol, and the solid content of the Zonyl FSA in the low surface energy chemical phase is 10%;

wherein the inorganic micron particles are 9 μm zirconium dioxide micron particles, the inorganic nano particles are 90nm aluminum oxide nano particles, and the mass ratio of the zirconium dioxide micron particles to the aluminum oxide nano particles is 10: 20; the second solvent is isopropanol; the total solid content of the zirconium dioxide micron particles and the aluminum oxide nano particles in the multi-level topological physical phase is 7 percent;

wherein the adhesive is a polyethylene glycol aqueous solution with solid content of 4.5%, and the volume of the adhesive is 10% of the total volume of the two phases of the low surface energy chemical phase and the multilevel topological physical phase.

The coating facing the oil-water separation switchable surface wettability is prepared by the following method:

(1) mixing Zonyl FSA and isopropanol to form a low surface energy chemical phase;

(2) ultrasonically mixing zirconium dioxide micron particles, aluminum oxide nano particles and isopropanol to form a multi-level topological physical phase;

(3) mixing the formed low surface energy chemical phase and the multi-level topological physical phase, adding a polyethylene glycol aqueous solution, sealing and standing for 5 hours, and discharging bubbles to form slurry;

(4) and (4) uniformly spraying the slurry prepared in the step (3) on an iron screen of 800 meshes, and naturally drying to obtain the iron-based composite material.

Comparative example 1

Super-hydrophobic-super-oleophilic coatings prepared by the method described by Hui Liu (Chemical Engineering Journal,2017, DOI: 10.1016/j.cej.2017.07.114).

Comparative example 2

A coating comprising a low surface energy chemical phase, a monolayer-level topological physical phase, and an adhesion agent; the low surface energy chemical phase includes a polar group fluoropolymer and a first solvent; the single-stage topological physical phase comprises inorganic microparticles and a second solvent; the volume ratio of the low surface energy chemical phase to the monolayer-level topological physical phase is 10: 4;

wherein the polar group fluoropolymer is Zonyl 9361, the first solvent is water, and the solid content of Zonyl 9361 in the low surface energy chemical phase is 3.5%;

wherein the inorganic microparticles are silica microparticles of 4 μm; the second solvent is ethanol; the solid content of the silica microparticles in the single-level topological physical phase is 3 percent;

wherein the adhesive is polyvinyl alcohol aqueous solution with solid content of 1.3%, and the volume of the adhesive is 5% of the total volume of the two phases of the low surface energy chemical phase and the single-layer topological physical phase.

The coating is prepared by the following method:

(1) mixing Zonyl 9361 with water to form a low surface energy chemical phase;

(2) ultrasonically mixing the silicon dioxide micron particles and ethanol to form a single-level topological physical phase;

(3) mixing the formed low surface energy chemical phase with the single-layer topological physical phase, adding a polyvinyl alcohol aqueous solution, sealing and standing for 1h, and discharging bubbles to form slurry;

(4) and (4) uniformly spraying the slurry prepared in the step (3) on a 200-mesh titanium screen, and naturally drying to obtain the titanium-based composite material.

Comparative example 3

A coating comprising a low surface energy chemical phase, a monolayer-level topological physical phase, and an adhesion agent; the low surface energy chemical phase includes a polar group fluoropolymer and a first solvent; the single-level topological physical phase comprises inorganic nanoparticles and a second solvent; the volume ratio of the low surface energy chemical phase to the monolayer-level topological physical phase is 10: 4;

wherein the polar group fluoropolymer is Zonyl 9361, the first solvent is water, and the solid content of Zonyl 9361 in the low surface energy chemical phase is 3.5%;

wherein the inorganic nanoparticles are titanium dioxide nanoparticles with the particle size of 20 nm; the second solvent is ethanol; the solid content of the titanium dioxide nanoparticles in the single-layer topological physical phase is 3 percent;

wherein the adhesive is polyvinyl alcohol aqueous solution with solid content of 1.3%, and the volume of the adhesive is 5% of the total volume of the two phases of the low surface energy chemical phase and the single-layer topological physical phase.

The coating is prepared by the following method:

(1) mixing Zonyl 9361 with water to form a low surface energy chemical phase;

(2) ultrasonically mixing titanium dioxide nanoparticles and ethanol to form a single-level topological physical phase;

(3) mixing the formed low surface energy chemical phase with the single-layer topological physical phase, adding a polyvinyl alcohol aqueous solution, sealing and standing for 1h, and discharging bubbles to form slurry;

(4) and (4) uniformly spraying the slurry prepared in the step (3) on a 200-mesh titanium screen, and naturally drying to obtain the titanium-based composite material.

Experimental data

First, surface property test

As shown in fig. 2, the coating prepared in example 1 had a contact angle of 4.7 ° for water and 152.6 ° for oil. In addition, the coating prepared in comparative example 1 had a contact angle of 154.7 ° with respect to water and a contact angle of 7.0 ° with respect to oil. The coating prepared in comparative example 2 had a contact angle of 41.8 ° for water and 120.6 ° for oil. The coating prepared in comparative example 3 had a contact angle of 35.2 ° for water and 129.7 ° for oil. It can be seen that the multi-level topological physical phase comprising inorganic microparticles and inorganic nanoparticles in the present application enables the prepared coating to have higher hydrophilicity and oleophobicity.

Second, testing the oil-water separation efficiency

The oil-water separation efficiency test method comprises the following steps: mixing water, soybean oil and a sodium dodecyl sulfate solution (a water solution with the mass concentration of 0.25%) according to a volume ratio of 8: 1: 1 mechanically stirring and mixing to form an oil-water emulsion; and (3) demulsifying the oil-water emulsion by a screen to complete two-phase separation, counting the volume of the separated water phase mixed oil phase, and calculating the oil-water separation efficiency: v_{Water (W)}/(V_{Water (W)}+V_Oil) In which V is_{Water (W)}And V_OilThe volume of the separated water phase and the volume of the intermixed oil phase, respectively.

The coating prepared in example 1 had an oil-water separation efficiency of 98.6%. The coating prepared in comparative example 1 had an oil-water separation efficiency of 75.3%.

Thirdly, switching of surface wetting property

The coatings prepared in example 1 were placed in solutions of different pH with water and oil contact angles as shown in table 1. As can be seen from table 1, when the coating was exposed to an aqueous solution having a pH of about 4.4, the coating had a contact angle of 150.7 ° with water and a contact angle of 155.0 ° with oil. It can be seen that the coating achieves a free switch from a superhydrophilic-superoleophobic surface to a superhydrophobic-superoleophobic surface in an acidic environment at a pH of about 4.4.

TABLE 1 contact angles for solutions of different pH values

The pH value of the coating placed in an aqueous environment	Water contact angle	Oil contact angle
			7.2	4.7°	152.6°
5.6	4.8°	153.8°
			4.7	11.2°	152.3°
4.4	150.7°	155.0°
			4.0	150.4°	154.5°

Fourth, acid corrosion resistance test

The coatings prepared in example 1 and comparative example 1 were placed in an acidic solution with a pH of 4.0 for 36 hours, dried at 75 ℃, left open for 48 hours, and the screens were subjected to elemental analysis tests, respectively, with the elemental analysis spectra shown in fig. 3. Fig. 3a is the screen of example 1 and fig. 3b is the screen of comparative example 1. As can be seen from fig. 3, the elemental analysis spectrum of the sieve in example 1 shows no oxygen peak, indicating that the sieve in example 1 has no rust, and the elemental analysis spectrum of the sieve in comparative example 1 shows an oxygen peak, indicating that the rust of the sieve in comparative example 1 is clearly visible.

The above-mentioned embodiments only express several embodiments of the present invention, and the description thereof is more specific and detailed, but not construed as limiting the scope of the present invention. It should be noted that, for a person skilled in the art, several variations and modifications can be made without departing from the inventive concept, which falls within the scope of the present invention. Therefore, the protection scope of the present patent shall be subject to the appended claims.