Super-hydrophobic-passivation dual-function coating as well as preparation method and application thereof

Abstract

The invention discloses a super-hydrophobic-passivation dual-function coating and a preparation method and application thereof.The preparation method comprises the steps that raw materials are weighed according to the mass ratio of silicon oxide to silane to a binder to an alkaline material to water being (0.5-1.0): (0.3-0.6): (0.5-1.5): (0.2-0.5): 20; the preparation method comprises the following steps: dispersing silicon oxide in water, adjusting the pH value of the solution to 7-11, adding silane and a binder, and uniformly mixing to obtain super-hydrophobic slurry; adding an alkaline material into the super-hydrophobic slurry, and uniformly mixing to obtain super-hydrophobic and passivated dual-functional slurry; and coating the super-hydrophobic-passivation dual-function slurry on the substrate, curing and drying. The super-hydrophobic-passivation dual-function coating has two functions of super-hydrophobic and passivation through synergistic compatibility of organic and inorganic components, and can be used for blocking dissolution and oxidation of sulfur and heavy metal elements in a mine and promoting AMD source prevention and control.

Description

Technical Field

[0001] The invention relates to a super-hydrophobic-passivation dual-functional coating and a preparation method and application thereof, and belongs to the field of water pollution control and mine pollution source prevention and control. Background Art

[0002] During mining, sulfur-containing iron minerals (such as pyrite FeS 2 A large amount of acid mine drainage (AMD) will be produced when AMD is exposed to oxygen and water, accompanied by microbial activity. AMD has a low pH value and high sulfate and iron content. The acid leaching environment caused by it causes other heavy metal ions to dissolve. It is a typical mine pollution problem and has caused serious damage to the water and soil environment. The main AMD treatment technologies include neutralization precipitation, adsorption, membrane separation, wetlands, permeable reaction walls (PRBs) and sulfate bioreactors (SBRs). However, end-of-pipe treatment is often difficult to eradicate environmental problems, and its effects are easily affected by time and space constraints, and there is secondary pollution. In comparison, source control is a more cost-effective green mine construction strategy. For source control of AMD, we should focus on blocking the contact pathways between sulfur-containing iron minerals and water and oxidizing media, inhibiting acid production, and controlling sulfate release.

[0003] After the oxidation of sulfur-containing iron minerals, an oxide film will be self-generated on the surface, which helps to slow down the further oxidation inside the mineral. This situation where the surface becomes inactive or anti-oxidation is called surface passivation. However, the passivation performance of the self-generated oxide film is unstable, and usually an external passivator is required to improve the passivation effect. Common passivators include phosphates, silicates, organic amines, humic acid, cellulose and silanes, which differ in film-forming conditions, use costs and environmental adaptability. For example, phosphates and silicates involve chemical pre-oxidation when used, and the cost of film making is relatively high; organic amines have certain environmental toxicity and are not suitable for large-scale use in relatively closed and poorly ventilated places; humic acid and cellulose have high biocompatibility, are easy to breed microorganisms, and accelerate the biochemical reactions of the passivation protection object; silanes contain organic silicon compounds, have strong adhesion and high antioxidant properties, but the film-forming process mostly requires the participation of volatile organic solvents, which is not suitable for use in places with high fire and explosion requirements. In addition, in view of the acid-generating characteristics of the oxidation of sulfide-containing iron minerals, alkaline materials are added to the passivation system to neutralize the acidity, provide active sites for complexation with sulfide-containing minerals, and promote a passivation coating that fits tightly with the substrate to prevent the overflow of heavy metal ions and sulfate. However, most surface passivators do not have a hydrophobic function or have weak hydrophobicity and cannot adapt to the wet environment of underground mineral mining. Superhydrophobic (contact angle > 150°) coatings have extremely strong liquid repellency and can effectively isolate aqueous solution erosion, which is beneficial to prevent sulfide-containing iron minerals from contacting mine water, thereby reducing AMD production. However, the preparation of superhydrophobic coatings often requires the participation of volatile organic solvents, and the durability of the coating needs to be improved.

[0004] Cement-based materials have excellent mechanical properties and are one of the most widely used building materials. They help to enhance the strength of film coatings, but their porosity and hydrophilicity can easily cause external Cl - 、SO 4 2- The invasion of corrosive ions such as ions causes the durability of cement-based materials to deteriorate. Superhydrophobic modification is an important means to enhance the anti-wetting and self-cleaning ability of cement-based materials, which mainly includes two methods: surface superhydrophobic modification and overall superhydrophobic modification. The former improves the hydrophobicity of the surface of cement-based materials through the penetration of superhydrophobic slurry, and rarely affects the mechanical properties of the material. In comparison, the latter will delay the cement hydration reaction and reduce the overall mechanical strength of the material due to the internal addition of hydrophobic materials. Summary of the invention

[0005] In view of the problems existing in the above-mentioned prior art, the present invention provides a super-hydrophobic-passivation dual-functional coating and a preparation method and application thereof.

[0006] In order to achieve the above object, a method for preparing a super hydrophobic-passivation dual-functional coating adopted by the present invention comprises the following steps:

[0007] (1) Weighing the raw materials according to the mass ratio of silicon oxide, silane, binder, alkaline material and water of (0.5-1.0):(0.3-0.6):(0.5-1.5):(0.2-0.5):20; dispersing silicon oxide in water, adjusting the pH value of the solution to 7-11, and then adding silane and binder and mixing to obtain a super hydrophobic slurry;

[0008] (2) adding an alkaline material to the super-hydrophobic slurry obtained in step (1), mixing them evenly, and obtaining a super-hydrophobic-passivation dual-functional slurry;

[0009] (3) coating the super hydrophobic-passivation dual-functional slurry of step (2) on the substrate, curing and drying.

[0010] As an improvement, the silicon oxide is in granular form with a particle size ranging from 10 to 50 nm.

[0011] As an improvement, the silane is any one of medium-chain alkoxysilane and its derivatives, with a purity of >95%.

[0012] As an improvement, the binder is any one of polyurethane and its derivatives, with a viscosity of 300-1500 mPa·s and a solid content of 20-40%.

[0013] As an improvement, the alkaline material is any one of calcium-containing minerals, calcium-containing salts, magnesium-calcium-containing minerals, and magnesium-calcium salts, and has a particle size greater than 75 μm.

[0014] The second aspect of the present invention also provides a super hydrophobic-passivation dual-functional coating, which is prepared by the preparation method.

[0015] In a third aspect of the present invention, there is also provided an application of the super-hydrophobic-passivation dual-functional coating prepared by the preparation method or described, for blocking the dissolution and oxidation of sulfur and heavy metal elements in mines; wherein the heavy metal elements in the mines are at least one of Fe, Cu, Pb, Zn, Cd, etc.;

[0016] The super hydrophobic-passivation dual-function coating is coated on the surface of a mineral substrate, a cement-based support layer is provided between the mineral substrate and the super hydrophobic-passivation dual-function coating, the super hydrophobic-passivation dual-function coating is provided with no less than 1 layer, and the cement-based support layer is provided with 0-1 layers.

[0017] As an improvement, the cement-based support layer comprises the following raw materials: cement, aggregate and water, the mass ratio of the cement to the aggregate is (70-50): (30-50), and the water-cement ratio is 0.5-0.8.

[0018] As an improvement, the aggregate is coal gangue with a particle size of 45-75 μm; and the cement is sulfate-resistant cement.

[0019] As an improvement, the following steps are included:

[0020] (1) dispersing silicon oxide in water, adjusting the pH value of the solution to 7-11, and then adding silane and a binder to mix to obtain a super hydrophobic slurry;

[0021] (2) adding an alkaline material to the super-hydrophobic slurry obtained in step (1), mixing them evenly, and obtaining a super-hydrophobic-passivation dual-functional slurry;

[0022] (3) mixing cement, aggregate and water uniformly to obtain cement-based slurry;

[0023] (4) coating the cement-based slurry of step (3) on the sulfide-containing iron mineral substrate, and forming a cement-based support layer after curing, and coating the super-hydrophobic-passivation dual-functional slurry of step (2) on the cement-based support layer, curing and drying; when the cement-based support layer is not included, directly coating the super-hydrophobic-passivation dual-functional slurry of step (2) on the substrate, curing and drying.

[0024] Mechanism of the present invention:

[0025] Hydrophobic groups are generated by silane hydrolysis and cross-linked with silicon oxide to form a network structure with Si-O-Si. The resulting agglomerates, under the action of the binder, form a micro-nano rough structure with low surface energy on the substrate surface, which has excellent superhydrophobicity; the added alkaline material further enhances the cross-linking effect of Si-O-Si, and promotes the replacement branching of metal elements (such as Fe) and HO-Si to produce Fe-O-Si bonds, so that the coating forms a more dense and uniform wrapping on the surface of the sulfur-containing iron mineral, blocking the path of sulfur-containing iron minerals being infiltrated and oxidized and heavy metals leaching.

[0026] From the coating structure point of view, the cement-based support layer strengthens the mechanical properties of the overall coating. The sulfate-resistant cement and gangue aggregate it contains can improve the passivation capacity. The surface roughness of the cement-based support layer is large, which is conducive to enhancing the adhesion of the superhydrophobic-passivation dual-functional coating. At the same time, after the superhydrophobic-passivation dual-functional slurry penetrates into the cement-based support layer and solidifies, a superhydrophobic encapsulation with a certain thickness is formed, which protects the support layer from erosion and further isolates the reaction channels of sulfur-containing iron minerals.

[0027] Compared with the prior art, the present invention has the following beneficial effects:

[0028] 1) The super-hydrophobic-passivation dual-function coating of the present invention has both super-hydrophobic and passivation effects through the synergistic combination of organic and inorganic components, inhibits acid and controls sulfur, and promotes the source prevention and treatment of AMD.

[0029] 2) The functional coupling of the super hydrophobic-passivation dual-functional coating and the cement-based support layer of the present invention significantly improves the durability and stability of the overall coating.

[0030] 3) The coating slurry provided by the present invention is prepared in a water solvent, does not require the participation of an organic solvent, is environmentally friendly, and is suitable for places with high requirements for fire and explosion prevention and relatively closed spaces.

[0031] 4) The preparation method of the coating of the present invention is simple and easy, with mild conditions, convenient operation, low cost, and can be used on a large area.

[0032] 5) The coating provided by the present invention can effectively block the dissolution and oxidation of sulfur and heavy metal elements, curb the generation of AMD, and help build green mines. BRIEF DESCRIPTION OF THE DRAWINGS

[0033] Figure 1 Static water contact angle diagrams of the super-hydrophobic coating (a) and the super-hydrophobic-passivation dual-functional coating (b) prepared in Example 1 of the present invention;

[0034] Figure 2 SEM images of pyrite coated with a super-hydrophobic coating (a) and a super-hydrophobic-passivation dual-functional coating (b) prepared in Example 1 of the present invention;

[0035] Figure 3 SO in Example 1 of the present invention 4 2- Content (a) and total iron content (b) over time;

[0036] Figure 4 The anti-wetting performance of the coating (cement-based support layer + super-hydrophobic-passivation dual-functional coating) of Example 2 of the present invention;

[0037] Figure 5 Schematic diagram of chemical leaching of the coating (cement-based support layer + super-hydrophobic-passivation dual-functional coating) of Example 2 of the present invention. DETAILED DESCRIPTION

[0038] In order to make the objectives, technical solutions and advantages of the present invention more clear, the technical solutions of the present application are described in detail through specific embodiments below. It should be understood that the embodiments of the present application and the specific features in the embodiments are detailed descriptions of the technical solutions of the present application, rather than limitations on the technical solutions of the present application.

[0039] Example 1

[0040] A method for preparing a super hydrophobic-passivation dual-functional coating comprises the following steps:

[0041] (1) First, weigh the raw materials according to the mass ratio of silicon oxide, silane, binder, alkaline material and water of 0.8:0.3:1.0:0.4:20; wherein the silicon oxide is silicon oxide, which is granular and has a particle size range of 10-50 nm; the silane is alkoxysilane (carbon number 15) with a purity of >95%; the binder is polyurethane (viscosity 1200 mPa·s, solid content 35%); the alkaline material is calcium carbonate mineral with a particle size greater than 75 μm;

[0042] Disperse silicon oxide in water, adjust the solution pH to 10, add alkoxysilane and polyurethane, mix well, and stir for 16 hours to obtain a uniformly dispersed superhydrophobic slurry;

[0043] (2) adding calcium carbonate mineral to the super-hydrophobic slurry obtained in step (1) to obtain a super-hydrophobic-passivation dual-functional slurry;

[0044] (3) placing the pyrite powder in the super-hydrophobic slurry of step (1) and the super-hydrophobic-passivation dual-functional slurry of step (2), stirring and coating at room temperature for 4 hours, then taking it out, and naturally curing it at room temperature (25±5° C.) for 16 hours to form a super-hydrophobic coating and a super-hydrophobic-passivation dual-functional coating covering the pyrite powder, respectively;

[0045] The static water contact angle test result of the super hydrophobic coating is 157.32° ( Figure 1 (a)), the static water contact angle test result of the super hydrophobic-passivation dual-functional coating is 158.74° (e.g. Figure 1 (b)), indicating that the addition of alkaline materials has little effect on the superhydrophobic properties of the coating. The appearance of the two coatings is shown in Figure 2 As shown in Figure 2, it was found that the superhydrophobic-passivation dual-functional coating was thicker and denser, with more surface micro-convexities, showing better superhydrophobic performance. Figure 1 The results are consistent.

[0046] Uncoated pyrite powder, super-hydrophobic coated pyrite powder and super-hydrophobic-passivation dual-functional coating coated pyrite powder were placed in 0.5% H 2 O 2 The reaction was carried out in the solution for 24 hours, and the SO in the solution was determined. 4 2- Content and total iron content and passivation rate, the results are as follows Figure 3 As shown in the figure, the uncoated pyrite powder rapidly released a large amount of iron and sulfate ions, which was unable to prevent H 2 O 2 The erosion of the solution, while the pyrite powder wrapped in the coating is 2 O 2The superhydrophobic-passivation dual-functional coating has strong tolerance to SO 4 2- The 24h passivation rates of superhydrophobic coating and total iron reached 93.83% and 99.70% respectively, which were 51.80% and 96.05% higher than those of single superhydrophobic coating. Compared with various reported coatings, the hydrophobic and passivation properties were stronger (as shown in Table 1 below), thus showing excellent antioxidant effect.

[0047] Table 1 Comparison of hydrophobicity and passivation properties of different coatings

[0048]

[0049]

[0050] Example 2

[0051] The difference from Example 1 is that this embodiment further includes a cement-based support layer, and the specific steps are:

[0052] (1) According to the mass ratio of sulfate-resistant cement to coal gangue of 60:40 and the water-cement ratio of 0.6, the raw materials were weighed; sulfate-resistant cement (HSR 42.5) and coal gangue (particle size 45-75 μm) were added to water, stirred for 3 minutes, mixed evenly, coated on the surface of the pyrite test block, and cured at room temperature for 72 hours to obtain a cement-based support layer;

[0053] (2) The super-hydrophobic-passivation dual-functional slurry prepared in Example 1 is sprayed on the surface of the cement-based support layer of step (1), and the spraying is stopped when the slurry no longer seeps downward. After the spraying is completed, the slurry is cured at ambient temperature for 18 hours to obtain a coating capable of blocking the oxidation of sulfur-containing iron minerals and controlling sulfur and inhibiting acid.

[0054] The anti-wetting properties of the obtained samples are as follows: Figure 4 As shown, the water droplets condense and do not wet. After the obtained sample was immersed in water for 30 days, the color of the water still did not change, indicating that there was basically no Fe release (such as Figure 5 ).

[0055] Example 3

[0056] A method for preparing a super-hydrophobic coating comprises the following steps:

[0057] (1) dispersing silicon oxide in water according to the mass ratio of silicon oxide, silane, binder and water of 0.7:0.5:0.8:20, adjusting the pH value of the solution to 10, then adding alkoxysilane (carbon number 15) and polyurethane (viscosity 1200 mPa·s, solid content 35%), mixing, stirring for 16 hours, and obtaining a uniformly dispersed superhydrophobic slurry;

[0058] (2) The super-hydrophobic slurry prepared in step (1) was sprayed on the surface of the glass substrate, and after the surface was dried, the second spray was applied. After the spraying was repeated 5 times, the slurry was naturally cured at room temperature (25±5° C.) for 20 h to form a super-hydrophobic coating.

[0059] The contact angle test was carried out on the super-hydrophobic coating sprayed each time. The static water contact angles of the 1st to 5th layers of coating after superposition were 153.66°, 153.82°, 157.49°, 152.82° and 152.82°, respectively, indicating that after three sprayings, the super-hydrophobic performance of the coating was better.

[0060] Example 4

[0061] The difference from Example 1 is that the silane used in this case is a combination of two silanes, and the added alkaline material is calcium magnesium carbonate mineral. The specific steps are:

[0062] (1) weighing the raw materials according to the mass ratio of silicon oxide, silane (composed of alkoxysilane and aminosilane in a mass ratio of 1:1), binder, alkaline material and water in a ratio of 1.0:0.6:0.7:0.3:20; dispersing silicon oxide in water, adjusting the pH value to 8, then adding alkoxysilane (carbon number 18), aminosilane (carbon number 6) and polyurethane (viscosity 1200 mPa·s, solid content 35%) and mixing, stirring for 10 hours to obtain a uniformly dispersed superhydrophobic slurry;

[0063] (2) adding calcium magnesium carbonate mineral to the super hydrophobic slurry obtained in step (1) to obtain a super hydrophobic-passivation dual-functional slurry;

[0064] (3) Spray the super-hydrophobic-passivation dual-functional slurry prepared in step (2) onto the surface of the pyrite block, repeat the spraying three times, and then naturally cure at room temperature (25±5°C) for 20 hours to form a super-hydrophobic-passivation dual-functional coating.

[0065] Example 5

[0066] A method for preparing a super hydrophobic-passivation dual-functional coating comprises the following steps:

[0067] (1) weighing the raw materials according to the mass ratio of silicon oxide, silane (composed of alkoxysilane and aminosilane in a mass ratio of 1:3), binder, alkaline material and water in a ratio of 0.5:0.3:0.5:0.4:20; dispersing silicon oxide in water, adjusting the pH value to 7, then adding alkoxysilane (carbon number 18), aminosilane (carbon number 9) and polyurethane (viscosity 300 mPa·s, solid content 32%) and mixing, stirring for 10 hours to obtain a uniformly dispersed superhydrophobic slurry;

[0068] (2) adding calcium silicate to the super-hydrophobic slurry obtained in step (1) to obtain a super-hydrophobic-passivation dual-functional slurry;

[0069] (3) Spray the super-hydrophobic-passivation dual-functional slurry prepared in step (2) onto the surface of the cement block, repeat the spraying 5 times, and naturally cure at room temperature (25±5°C) for 18 hours to form a super-hydrophobic-passivation dual-functional coating.

[0070] In the description provided herein, a large number of specific details are described. However, it is understood that embodiments of the present invention can be practiced without these specific details. In some instances, well-known methods, structures and techniques are not shown in detail so as not to obscure the understanding of this description.

[0071] The above is only a preferred embodiment of the present invention, and does not limit the present invention in any form. Although the present invention has been disclosed as a preferred embodiment as above, it is not used to limit the present invention. Any technician familiar with this patent can make some changes or modify the technical contents suggested above into equivalent embodiments without departing from the scope of the technical solution of the present invention. However, any simple modification, equivalent change and modification made to the above embodiments according to the technical essence of the present invention without departing from the content of the technical solution of the present invention still fall within the scope of the solution of the present invention.

Claims

1. A method for preparing a super hydrophobic-passivation dual-function coating, characterized in that: The following steps are involved: (1) Weighing the raw materials according to the mass ratio of silicon oxide, silane, binder, alkaline material and water of (0.5-1.0):(0.3-0.6):(0.5-1.5):(0.2-0.5):20; dispersing silicon oxide in water, adjusting the pH value of the solution to 7-11, and then adding silane and binder and mixing to obtain a super hydrophobic slurry; (2) adding an alkaline material to the super-hydrophobic slurry obtained in step (1), mixing them evenly, and obtaining a super-hydrophobic-passivation dual-functional slurry; (3) coating the super hydrophobic-passivation dual-functional slurry of step (2) on the substrate, curing and drying.

2. The method for preparing a super hydrophobic-passivation dual-function coating according to claim 1, wherein: The silicon oxide is in granular form, and the particle size ranges from 10 to 50 nm.

3. The method for preparing a super hydrophobic-passivation dual-function coating according to claim 1, wherein: The silane is any one of medium-chain alkoxysilane and its derivatives, with a purity of >95%.

4. The method for preparing a super hydrophobic-passivation dual-function coating according to claim 1, wherein: The binder is any one of polyurethane and its derivatives, with a viscosity of 300-1500 mPa·s and a solid content of 20-40%.

5. The method for preparing a super hydrophobic-passivation dual-function coating according to claim 1, wherein: The alkaline material is any one of calcium-containing minerals, calcium-containing salts, magnesium-calcium-containing minerals, and magnesium-calcium-containing salts, and the particle size is greater than 75 μm.

6. A super hydrophobic-passivation dual-function coating, characterized in that: The method is prepared by the preparation method according to any one of claims 1 to 5.

7. An application of a super hydrophobic-passivation dual-functional coating obtained by the preparation method according to any one of claims 1 to 5 or according to claim 6, characterized in that: Used to block the dissolution and oxidation of sulfur and heavy metal elements in mines; The super hydrophobic-passivation dual-function coating is coated on the surface of a mineral substrate, a cement-based support layer is provided between the mineral substrate and the super hydrophobic-passivation dual-function coating, the super hydrophobic-passivation dual-function coating is provided with no less than 1 layer, and the cement-based support layer is provided with 0-1 layers.

8. The use of a super hydrophobic-passivation dual-function coating according to claim 7, characterized in that: The cement-based support layer comprises the following raw materials: cement, aggregate and water, wherein the mass ratio of the cement to the aggregate is (70-50): (30-50), and the water-cement ratio is 0.5-0.

8.

9. The use of a super hydrophobic-passivation dual-function coating according to claim 8, characterized in that: The aggregate is coal gangue with a particle size of 45-75 μm; and the cement is sulfate-resistant cement.

10. The use of a super hydrophobic-passivation dual-function coating according to claim 7, characterized in that: The following steps are involved: (1) dispersing silicon oxide in water, adjusting the pH value of the solution to 7-11, and then adding silane and a binder to mix to obtain a super hydrophobic slurry; (2) adding an alkaline material to the super-hydrophobic slurry obtained in step (1), mixing them evenly, and obtaining a super-hydrophobic-passivation dual-functional slurry; (3) mixing cement, aggregate and water uniformly to obtain cement-based slurry; (4) coating the cement-based slurry of step (3) on the sulfide-containing iron mineral substrate, and forming a cement-based support layer after curing, and coating the super-hydrophobic-passivation dual-functional slurry of step (2) on the cement-based support layer, curing and drying; when the cement-based support layer is not included, directly coating the super-hydrophobic-passivation dual-functional slurry of step (2) on the substrate, curing and drying.

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