A method for preparing surface-modified hollow glass microspheres

Abstract

This invention relates to a method for preparing surface-modified hollow glass microspheres, characterized in that: (1) hollow glass microspheres prepared by the glass powder method are placed in a vibrating sieve and sorted to obtain microspheres with a median diameter of 5 μm to 90 μm and a true density of 0.2 to 0.6 g / cm³. 3 (1) Hollow glass microspheres; (2) Add anatase titanium dioxide sol aqueous coating liquid to a container, add hollow glass microspheres, so that they exist in a single particle layer or 2-3 layers on the surface of the coating liquid; (3) Spray solvent-based resin coating liquid onto the glass microspheres floating on the surface of the coating liquid, let stand, and initially form and solidify the film; (4) Take out the glass microspheres, place them in a filter bag, and spin dry, dry, and sinter them through a centrifugal process. Advantages of this invention: The hydrophilic surface modification and hydrophobic surface modification processes are carried out in the same container, which improves the operation efficiency and shortens the process flow; The modified hollow glass microspheres have both hydrophilic and hydrophobic film layers, which can be used to treat oil pollution on the water surface, thus improving the oil pollution treatment efficiency.

Description

Technical Field

[0001] This invention belongs to the field of powder surface treatment technology, and relates to a method for preparing surface-modified hollow glass microspheres. Background Technology

[0002] Hollow glass microspheres, after special treatment, can be used as adsorbents in wastewater treatment (their high specific surface area allows them to effectively adsorb harmful substances in wastewater, such as heavy metal ions and organic pollutants). In some advanced oxidation and photocatalytic wastewater treatment technologies, hollow glass microspheres are also used as carriers or catalyst components to enhance treatment effects.

[0003] Hollow glass microspheres with specific surface modifications can fix water surface pollutants on the surface of the microspheres through physical or chemical adsorption to achieve the purpose of purifying wastewater. In some cases, the surface of hollow glass microspheres is loaded with catalyst components, which promote the degradation of organic pollutants in wastewater into harmless substances through catalysis.

[0004] Powder-processed hollow glass microspheres exhibit high strength and a dense, smooth, and intact shell surface. Preparing a porous structure on the surface of hollow glass microspheres provides a larger specific surface area and space, which is beneficial for applications such as adsorption and catalysis, enhancing the role of glass microspheres as carriers. To achieve glass porosity, methods such as thermal phase separation and filling can be employed. Thermal phase separation involves heating the glass to separate it into an alkali-rich phase and a silica-oxygen-rich phase. Then, an inorganic acid of appropriate concentration is used to dissolve the soluble phase of the separated glass microspheres, thus forming porous glass microspheres. However, thermal phase separation has strict requirements on the composition of the glass microspheres, and microsphere breakage often occurs during acid etching, resulting in low yield, low strength, and fragility of the obtained porous glass microspheres, limiting their applications. The filling method involves mixing graded glass microspheres and a pore-forming agent in a specific ratio, agglomerating the material into spheres using a rolling granulation method, and then sintering them in a furnace. After heat treatment, the spheres are washed with hot water, dilute acid, and cold water, respectively, to remove the pore-forming agent, yielding porous glass spheres. However, the filling method is suitable for preparing porous glass with high porosity and interconnected pores with millimeter to micrometer-sized pores, but not for preparing nanoscale porous structures. Besides porosification, another method for surface treatment of hollow glass microspheres is surface coating. As an additive, if added to an oily matrix material system, the surface of the glass microspheres generally needs to be coated with a coupling agent to improve the mixing effect and increase the adhesion between the microspheres and the oily matrix; at the same time, a dispersant is also needed to prevent mutual attraction and aggregation between the glass microspheres. However, when glass microspheres are used for treating oily water pollution, their role is adsorption and as a carrier for catalytic decomposition reactions. If a dispersant is used to prevent the glass microspheres from agglomerating on the oily water surface, it increases the technical complexity and introduces a new "pollutant" into the water. That is, the addition of the dispersant also leads to another form of water pollution, requiring additional purification. Summary of the Invention

[0005] The purpose of this invention is to overcome the shortcomings of the prior art and provide a method for preparing surface-modified hollow glass microspheres.

[0006] To achieve the above objectives, the technical solution adopted by the present invention is as follows:

[0007] A method for preparing surface-modified hollow glass microspheres, characterized by comprising the following steps:

[0008] (1) Hollow glass microspheres prepared by the glass powder method were placed in a vibrating sieve and sorted to obtain a median diameter D50 of 5 μm to 90 μm and a true density of 0.2 g / cm³. 3 ~0.6g / cm 3 Hollow glass microsphere powder;

[0009] (2) Add anatase titanium dioxide sol aqueous coating liquid to the container, and then add the hollow glass microsphere powder obtained in step (1), and control the glass microsphere powder to exist in the form of a single particle layer or a few layers (2~3 layers) on the surface of the coating liquid.

[0010] (3) Spray solvent-based resin coating liquid onto glass microspheres floating on the surface of the coating liquid. The solvent-based resin coating liquid uses aromatic hydrocarbons, ethers, esters, ketones, halogenated hydrocarbons, etc. as dispersion media, and water-resistant and oleophilic resins such as polyacrylate, polyester, polyurethane, epoxy resin, polysiloxane, etc. and their composite modified resins as film-forming materials. It uses anatase nano-TiO2 powder (particle size distribution between 5 nm and 20 nm) with oleophilic surface as filler. The amount of filler added is 0 to 3% of the mass of the coating liquid. After coating, let it stand to dry the surface and form a preliminary film.

[0011] The solvent-based resin coating liquid on the top of the hollow glass microspheres is immiscible with the aqueous coating liquid below. The sprayed solvent-based resin coating liquid adheres to the remaining surface of the glass microspheres that is not contacted by the aqueous coating liquid, thus giving the glass microspheres floating on the surface of the aqueous coating liquid a surface modified morphology in which the lower part is coated with aqueous anatase titanium dioxide sol and the upper part is coated with solvent-based resin.

[0012] (4) After the solvent-based resin attached to the glass microspheres has initially cured, the glass microspheres are taken out with a filter screen, placed in a filter bag, and then the glass microspheres are dried by centrifugation. They are then taken out and placed in a forced-air drying oven at 90℃~150℃ for 10min~30min for further drying. Finally, the film layer is sintered and cured by heating in an electric furnace at 200℃~350℃ for 5min~30min to obtain surface-modified hollow glass microspheres.

[0013] Furthermore, in step (1), the glass powder method involves feeding micron-sized glass powder into a spheroidizing furnace. Under the action of a high-temperature flame, the glass powder melts and expands into hollow glass microspheres with a dense and smooth surface. The spheroidized glass microspheres are collected by a cyclone separator. By using liquid flotation and adjusting the density of the liquid, hollow glass microspheres of different densities can be floated. Hollow glass microspheres with a density less than that of water are separated by water flotation. The true density measured by the water displacement method is 0.2 g / cm³. 3 ~0.6g / cm 3 .

[0014] Furthermore, in step (1), the particle size distribution span of the hollow glass microspheres is no greater than 1.0, and the particle size distribution span is calculated as (D90-D10) / D50.

[0015] Furthermore, in step (2), the nanocrystalline titanium dioxide particles in the titanium dioxide sol have a particle size of 5nm~30nm; and the solid content of the anatase titanium dioxide sol is 2.5%~4.5% based on TiO2.

[0016] Furthermore, in step (2): to ensure the microspheres float on the liquid surface, the density of the titanium dioxide sol-based aqueous coating solution is not less than 0.75 g / cm³. 3 .

[0017] Furthermore, the dispersion medium in step (3) includes, but is not limited to, toluene, xylene, dimethyl ether, diethyl ether, ethyl acetate, butyl acetate, methyl isobutyl ketone, and dichloromethane.

[0018] Furthermore, after step (4) is completed, meltblown polypropylene absorbent cotton is used to absorb and remove the small amount of oily coating liquid remaining on the surface of the water-based coating liquid, in preparation for the next batch of hollow glass microspheres surface modification process.

[0019] This invention creatively provides a glass microsphere with a composite surface that combines hydrophilicity and hydrophobicity, and its preparation method. By utilizing the density difference between the glass microsphere and the coating liquid, as well as the immiscibility of the two coating liquids, hollow glass microspheres are made to float on a high-density aqueous coating liquid. The lower part of the surface of the microsphere is coated, and a solvent-based oily coating liquid is dropped or sprayed onto the upper part of the surface of the microsphere. After a curing process, surface-modified hollow glass microspheres are formed.

[0020] The beneficial effects of this invention are:

[0021] (1) The hydrophilic surface modification and hydrophobic surface modification processes are carried out in the same container to improve operating efficiency and reduce process flow.

[0022] (2) The hollow glass microspheres modified by the present invention have both hydrophilic and hydrophobic membrane layers. When used to treat oil pollution on the water surface, they can be fully dispersed on the oily and sewage surface, avoiding the decrease in working efficiency caused by the agglomeration of powder. They can also decompose the adsorbed oil pollution in a timely manner by their own photocatalytic membrane layer or the photocatalytic membrane layer of the adjacent microspheres. This effectively improves the cumbersome process of collecting, desorbing, and replacing the completely hydrophilic photocatalytic decomposition membrane layer caused by the agglomeration of microspheres, and the completely oily adsorption membrane layer losing its adsorption capacity after adsorption saturation. This improves the efficiency of oil pollution treatment. Attached Figure Description

[0023] Figure 1 This is a schematic diagram of the preparation of a surface-modified hollow glass microsphere, where 1 is a container for the coating liquid and glass microspheres, 2 is an aqueous coating liquid, 3 is a solvent-based resin coating liquid, which is added by spraying in the figure, and 4 is a hollow glass microsphere.

[0024] Figure 2 This is a schematic cross-sectional view of a surface-modified hollow glass microsphere, where 5 is the hydrophilic film layer of the glass microsphere, 6 is the oleophilic film layer of the glass microsphere, 7 is the shell wall of the glass microsphere, and 8 is the hollow inner cavity of the glass microsphere. Detailed Implementation

[0025] The invention will be further described below with reference to the accompanying drawings:

[0026] The hollow glass microspheres of this invention are produced using a glass powder method. Micron-sized glass powder is fed into a spheroidizing furnace, where it melts and expands under high-temperature flame to form dense, smooth hollow glass microspheres. The spheroidized microspheres are collected by a cyclone separator. Different densities of hollow glass microspheres can be floated using liquid flotation by controlling the liquid density. Hollow glass microspheres with a density less than water are separated using a water flotation method. The true density measured by the water displacement method is 0.2 g / cm³. 3 ~0.6 g / cm 3 .

[0027] A method for preparing surface-modified hollow glass microspheres, the specific implementation steps of which are as follows: Example

[0028] (1) Hollow glass microspheres prepared by the glass powder method were placed in a vibrating sieve and sorted to obtain a median diameter (D50) of 30 μm, a particle size distribution span of 0.8, and a true density of 0.36 g / cm³. 3 Hollow glass microsphere powder;

[0029] (2) Anatase-type aqueous titanium dioxide sol (nanocrystalline titanium dioxide particle size of 10 nm~15 nm) was used and diluted with water to a solid content of 3.5% (density of 1.10 g / cm³). 3Add the contents to a 1000mL beaker with a 10cm diameter until it reaches about half its height. Then add 0.056g of the hollow glass microspheres obtained in step (1) to the beaker, so that the glass microsphere powder exists on the liquid surface mainly in the form of a single particle layer or a few layers (2~3 layers). Figure 1 (as shown)

[0030] (3) Spraying MQ104 methyl MQ type silicone resin [(CH3)3SiO] with toluene as the dispersion medium and 15% by mass fraction onto the floating hollow glass microspheres. 1 / 2 ] a [SiO 4 / 2 ] b A solvent-based resin coating liquid was prepared using 1.5% by mass of anatase nano-TiO2 powder with a particle size of 15 nm to 20 nm as the film-forming material and as the filler. The liquid was then applied to the surface of the microspheres and allowed to stand for 10 minutes to dry the film surface.

[0031] (4) After the solvent-based silicone resin adhering to the upper part of the hollow glass microspheres has initially cured, the glass microspheres are scooped out using a filter screen and placed in a filter bag. Then, the glass microspheres are centrifuged to dry. They are then placed in a forced-air drying oven and kept at 120℃ for 20 min for further drying. Finally, the film layer is sintered and cured by heating in an electric furnace at 300℃ for 5 min to obtain surface-modified hollow glass microspheres (e.g., Figure 2 (As shown).

[0032] 0.06 g of No. 0 diesel oil and 299.94 mL of pure water were added to a crystallizing dish with a diameter of 10 cm. Then, the surface-modified hollow glass microspheres prepared in this example were added. After magnetic stirring for 10 minutes, the dish was placed outdoors under natural light for 8 hours (Bengbu, November, sunny daytime, 8:30-16:30). The amount of diesel oil remaining was determined by spectrophotometry, and the diesel oil removal rate was calculated to be 72.2%. Example

[0033] (1) Hollow glass microspheres prepared by the glass powder method were placed in a vibrating sieve and sorted to obtain a median diameter D50 of 50 μm, a particle size distribution span of 0.6, and a true density of 0.32 g / cm³. 3 Hollow glass microsphere powder;

[0034] (2) Anatase-type aqueous titanium dioxide sol (nanocrystalline titanium dioxide particle size of 20nm~30nm) was used and diluted with water to a solid content of 3.0% (density of 1.05 g / cm³). 3 Add the contents to a crystallizing dish with a diameter of 20 cm to about half its height, and then add 0.335 g of the hollow glass microspheres obtained in step (1) to the dish, so that the glass microsphere powder exists on the liquid surface mainly in the form of a single particle layer or a few layers (2~3 layers). Figure 1 (as shown)

[0035] (3) Spray a solvent-based polyacrylate resin coating liquid (without TiO2 filler) prepared with methyl isobutyl ketone as the dispersion medium and 20% by mass of thermoplastic polyacrylate as the film-forming agent onto the floating hollow glass microspheres, so that it adheres and spreads to the upper surface of the microspheres, and let it stand for 15 minutes to achieve film surface drying.

[0036] (4) After the solvent-based polyacrylate resin adhering to the upper part of the glass microspheres has initially cured, the glass microspheres are removed using a filter screen and placed in a filter bag. Then, the glass microspheres are centrifuged to dry. They are then placed in a forced-air drying oven at 110°C for 30 min for further drying. Finally, the film layer is sintered and cured by heating in an electric furnace at 230°C for 15 min to obtain surface-modified hollow glass microspheres (e.g., Figure 2 (As shown).

[0037] 0.2g of No. 0 diesel oil and 999.8mL of pure water were added to a crystallizing dish with a diameter of 20cm. Then, the surface-modified hollow glass microspheres prepared in this example were added. After magnetic stirring for 10 minutes, the dish was placed outdoors under natural light for 8 hours (Bengbu, November, sunny daytime, 8:30-16:30). The amount of diesel oil remaining was determined by spectrophotometry, and the diesel oil removal rate was calculated to be 50.6%.

Claims

1. A method for preparing surface-modified hollow glass microspheres, characterized in that... Includes the following steps: (1) Hollow glass microspheres prepared by the glass powder method were placed in a vibrating sieve and sorted to obtain a median diameter D50 of 5 μm to 90 μm and a true density of 0.2 g / cm³. 3 ~0.6 g / cm 3 Hollow glass microsphere powder; (2) Add anatase nanocrystalline titanium dioxide sol aqueous coating liquid to the container, and then add the hollow glass microsphere powder obtained in step (1), and control the glass microsphere powder to exist in a single particle layer or 2~3 layers on the surface of the coating liquid. (3) Spray solvent-based resin coating liquid onto glass microspheres floating on the surface of the coating liquid. The solvent-based resin coating liquid uses aromatic hydrocarbons, ethers, esters, ketones, and halogenated hydrocarbons as dispersion media, polyacrylate, polyester, polyurethane, epoxy resin, polysiloxane resin and their composite modified resins as film-forming materials, and anatase nano-TiO2 powder with a surface oleophilic particle size distribution of 5 nm to 20 nm as filler. The amount of filler added is 0 to 3% of the mass of the coating liquid. After coating, let it stand to allow the surface to dry and form a preliminary film. (4) After the solvent-based resin attached to the glass microspheres has initially cured, the glass microspheres are taken out with a filter screen, placed in a filter bag, and then the glass microspheres are dried by centrifugation. They are then taken out and placed in a forced-air drying oven at 90℃~150℃ for 10 min~30 min for further drying. Finally, the film layer is sintered and cured by heating in an electric furnace at 200℃~350℃ for 5 min~30 min to obtain surface-modified hollow glass microspheres.

2. The method for preparing surface-modified hollow glass microspheres according to claim 1, characterized in that: In step (1), the glass powder method involves feeding micron-sized glass powder into a spheroidizing furnace. Under the action of a high-temperature flame, the glass powder melts and expands into hollow glass microspheres with a dense and smooth surface. The spheroidized glass microspheres are collected by a cyclone separator. By using liquid flotation and adjusting the density of the liquid, hollow glass microspheres of different densities can be floated. Hollow glass microspheres with a density less than that of water are separated by water flotation. The true density measured by the water displacement method is 0.2 g / cm³. 3 ~0.6 g / cm 3 .

3. The method for preparing surface-modified hollow glass microspheres according to claim 1, characterized in that: In step (1), the particle size distribution span of the hollow glass microspheres is no greater than 1.

0.

4. The method for preparing surface-modified hollow glass microspheres according to claim 1, characterized in that: In step (2), the nanocrystalline titanium dioxide particles in the titanium dioxide sol have a particle size of 5nm~30nm.

5. The method for preparing surface-modified hollow glass microspheres according to claim 1, characterized in that: In step (2), the solid content of the anatase titanium dioxide sol is 2.5% to 4.5% based on TiO2.

6. The method for preparing surface-modified hollow glass microspheres according to claim 1, characterized in that: In step (2), the density of the titanium dioxide sol-gel aqueous coating solution is not less than 0.75 g / cm³. 3 .

7. The method for preparing surface-modified hollow glass microspheres according to claim 1, characterized in that: The dispersion medium in step (3) includes, but is not limited to, toluene, xylene, diethyl ether, ethyl acetate, butyl acetate, methyl isobutyl ketone, and dichloromethane.

8. A method for preparing surface-modified hollow glass microspheres according to any one of claims 1-7, characterized in that: After step (4) is completed, meltblown polypropylene absorbent cotton is used to absorb and remove the small amount of oily coating liquid remaining on the surface of the water-based coating liquid, in preparation for the next batch of hollow glass microspheres surface modification process.

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