Preparation method of surface modified hollow glass beads

Abstract

The invention relates to a preparation method of surface modified hollow glass beads, which is characterized by comprising the following steps: (1) putting hollow glass beads prepared by a glass powder method into a rotary vibration sieve, and sorting to obtain hollow glass beads with the median diameter of 5-90 microns and the true density of 0.2-0.6 g / cm < 3 >; (2) adding the anatase type titanium dioxide sol water-based coating liquid into a container, and adding hollow glass beads, so that the hollow glass beads basically exist on the liquid surface of the coating liquid in the form of a single particle layer or 2-3 layers; (3) spraying a solvent type resin film coating liquid on the glass beads floating on the liquid surface of the film coating liquid, standing, preliminarily forming a film, and curing; and (4) fishing out the glass beads, placing the glass beads in a filter bag, and carrying out spin-drying, drying, sintering and curing on the glass beads through a centrifugation process. The method has the advantages that the hydrophilic surface modification process and the hydrophobic surface modification process are carried out in the same container, the operation efficiency is high, and the technological process is short; the modified hollow glass bead has both a hydrophilic film layer and a hydrophobic film layer, and can be used for treating oil stains on the water surface, so that the oil stain treatment efficiency is improved.

Description

Technical Field

[0001] The invention belongs to the technical field of powder surface treatment and relates to a method for preparing surface-modified hollow glass microspheres. Background Art

[0002] After special treatment, hollow glass microspheres can be used as adsorbents for sewage treatment (their high specific surface area enables them to effectively adsorb harmful substances in wastewater, such as heavy metal ions, organic pollutants, etc.). In some advanced oxidation, photocatalysis and other sewage treatment technologies, hollow glass microspheres are also used as carriers or catalyst components to enhance the treatment effect.

[0003] Hollow glass microspheres that have undergone 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 sewage; in some cases, the surface of the hollow glass microspheres is loaded with catalyst components, which promote the degradation of organic pollutants in the wastewater into harmless substances through catalytic action.

[0004] Hollow glass microspheres prepared by the powder method have high strength, and the shell wall surface is dense, smooth and complete. The porous structure prepared on the surface of hollow glass microspheres provides a larger specific surface area and space, which is conducive to applications such as adsorption and catalysis, and enhances the role of glass microspheres as carriers. In order to make the glass porous, thermal phase separation method, filling method, etc. can be used. The thermal phase separation method is to separate the glass into alkali-rich phase and silicon-rich phase by heating, and then use an inorganic acid of appropriate concentration to dissolve the soluble phase of the separated glass microspheres to form porous glass microspheres. However, the thermal phase separation method has strict requirements on the composition of glass microspheres, and the microspheres are often damaged during the acid etching process. The porous glass microspheres obtained have low yield, low strength and are fragile, which limits their application. The filling method mixes the graded glass microspheres and pore-forming agents in proportion, and uses the rolling granulation method to agglomerate the materials into balls and then sinter them in the furnace. After the insulation is completed, they are washed with hot water, dilute acid and cold water respectively. After the pore-forming agent is washed off, a porous glass sphere can be obtained. However, the filling method is suitable for the preparation of porous glass with high porosity and interconnected pores with pore sizes ranging from millimeters to micrometers, but is not suitable for the preparation of nano-scale porous structures. In addition to making the surface of hollow glass microspheres porous, another method is surface coating. As an additive, if an oily matrix material system is added, in order to improve the mixing effect, the surface of the glass microspheres is generally coated with a coupling agent to improve the adhesion between the microspheres and the oily matrix; at the same time, a dispersant is also required to prevent the mutual attraction and agglomeration between the glass microspheres. However, when glass microspheres are used to treat oil pollution on the water surface, the role of the glass microspheres is adsorption and as a carrier for catalytic decomposition reactions. If a dispersant is used to prevent the glass microspheres from agglomerating on the surface of the oily water, while increasing the technical complexity, new "pollutants" are added to the water body. That is, the addition of a dispersant will also lead to another form of pollution in the water body, requiring additional purification. Summary of the invention

[0005] The purpose of the present invention is to make up for the deficiencies of the prior art and provide a method for preparing surface-modified hollow glass microspheres.

[0006] In order to achieve the above object, the technical solution adopted by the present invention is as follows: A method for preparing surface-modified hollow glass microspheres, characterized by comprising the following steps: (1) The hollow glass microspheres prepared by the glass powder method were placed in a rotary vibrating screen and sorted to obtain a median diameter D50 of 5 μm to 90 μm and a true density of 0.2 g / cm 3 ~0.6g / cm 3 Hollow glass microsphere powder; (2) adding anatase-type titanium dioxide sol aqueous coating liquid into a container, and then adding the hollow glass microsphere powder obtained in step (1), controlling the glass microsphere powder to exist on the surface of the coating liquid in the form of a single particle layer or a few layers (2 to 3 layers); (3) Spray solvent-based resin coating liquid on the glass beads 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, polyacrylates, polyesters, polyurethanes, epoxy resins, polysiloxanes and other water-resistant, lipophilic resins and their composite modified resins as film-forming materials, and surface lipophilic anatase-type nano-TiO2 powder (particle size distribution in the range 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 the surface stand to dry and initially form a film. The solvent-based resin coating liquid on the hollow glass microspheres is incompatible with the aqueous coating liquid on the bottom. 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, so that the glass microspheres floating on the surface of the aqueous coating liquid present a surface-modified morphology in which the lower part is coated with the aqueous anatase titanium dioxide sol and the upper part is coated with the solvent-based resin. (4) After the solvent-based resin attached to the glass microbeads is initially cured, the glass microbeads are scooped out using a filter, placed in a filter bag, and then dried by centrifugation; taken out and placed in a forced air drying oven at 90°C to 150°C for 10 min to 30 min for further drying; finally, heated in an electric furnace at 200°C to 350°C for 5 min to 30 min to sinter and cure the film layer, thereby obtaining surface-modified hollow glass microbeads.

[0007] Furthermore, in the glass powder method in step (1), glass powder with micron-sized particles is conveyed into a spheroidizing furnace. Under the action of high-temperature flame, the glass powder melts and expands into hollow glass microspheres with dense and smooth surfaces. The spheroidized glass microspheres are collected by a cyclone. Through the liquid flotation method and by adjusting the density of the liquid, hollow glass microspheres with different densities can be floated. Through the water flotation method, hollow glass microspheres with a density less than that of water can be selected. The true density of the hollow glass microspheres tested by the water displacement method is 0.2 g / cm 3 ~0.6g / cm 3 .

[0008] Furthermore, in the 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.

[0009] Furthermore, in the step (2), the particle size of nanocrystalline titanium dioxide in the titanium dioxide sol is 5 nm to 30 nm; and the solid content of the anatase titanium dioxide sol is 2.5% to 4.5% based on TiO2.

[0010] Furthermore, in step (2), in order to make the microbeads float on the liquid surface, the density of the titanium dioxide sol aqueous coating liquid is not less than 0.75 g / cm 3 .

[0011] Furthermore, the dispersion medium in step (3) includes but is not limited to toluene, xylene, methyl ether, ethyl ether, ethyl acetate, butyl acetate, methyl isobutyl ketone, and dichloromethane.

[0012] Furthermore, after step (4) is completed, melt-blown polypropylene oil-absorbing cotton is used to absorb and remove a small amount of oily coating liquid remaining on the surface of the aqueous coating liquid, so as to prepare for the surface modification process of the next batch of hollow glass microspheres.

[0013] The present invention creatively provides a glass microbead with a composite surface having both hydrophilic and hydrophobic properties and a preparation method thereof. The density difference between the glass microbead and the coating liquid and the immiscibility of the two coating liquids are utilized to make the hollow glass microbead float on the high-density aqueous coating liquid, coat the surface of the lower part of the microbead, drip or spray a solvent-based oily coating liquid on the surface of the upper part of the microbead, and form a surface-modified hollow glass microbead through a curing process.

[0014] Beneficial effects of the present invention: (1) Carry out the hydrophilic surface modification and hydrophobic surface modification processes in the same container to improve operation efficiency and reduce process flow; (2) The hollow glass microspheres modified by the present invention have both a hydrophilic film layer and a hydrophobic film layer. When used to treat oil pollution on the water surface, they can be fully dispersed on the surface of the oily and polluted water to avoid the decrease in working efficiency caused by powder agglomeration, and the adsorbed oil pollution can be decomposed in time by relying on their own photocatalytic film layer or the photocatalytic film layer of the adjacent microspheres, which effectively improves the surface area reduction of the completely hydrophilic photocatalytic decomposition film layer due to the agglomeration of microspheres, and the complete oil adsorption film layer loses its adsorption capacity due to adsorption saturation, and the cumbersome process of collection, desorption, replacement, etc., thereby improving the efficiency of oil pollution treatment. BRIEF DESCRIPTION OF THE DRAWINGS

[0015] Figure 1 Schematic diagram of the preparation of surface-modified hollow glass microspheres, wherein 1 is a container for 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; Figure 2 Schematic diagram of the cross section of a surface-modified hollow glass microsphere, wherein 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 DESCRIPTION

[0016] The present invention will be further described below in conjunction with the accompanying drawings: The hollow glass microspheres of the present invention are prepared by a glass powder method, that is, glass powder with micron-sized particles is transported into a spheroidizing furnace, and under the action of a high-temperature flame, the glass powder is melted and expanded into hollow glass microspheres with a dense and smooth surface. The spheroidized glass microspheres are collected by a cyclone, and hollow glass microspheres with different densities can be floated by a liquid flotation method and by adjusting the density of the liquid. Hollow glass microspheres with a density less than that of water are selected by a water flotation method, and the true density thereof tested by a water displacement method is 0.2 g / cm 3 ~0.6 g / cm 3 .

[0017] A method for preparing surface-modified hollow glass microspheres, the specific implementation steps are as follows: Example

[0018] (1) The hollow glass microspheres prepared by the glass powder method were placed in a rotary vibrating screen 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 / cm 3 Hollow glass microsphere powder; (2) Use anatase-type aqueous titanium dioxide sol (nanocrystalline titanium dioxide particle size of 10 nm~15 nm) and dilute it with water to a solid content of 3.5% (density of 1.10 g / cm 3), add it to a 1000mL beaker with a diameter of 10 cm to about 1 / 2 of the height, add 0.056 g of the hollow glass microspheres obtained in step (1) therein, so that the glass microsphere powder exists on the liquid surface in the form of a single particle layer or a few layers (2 to 3 layers) ( Figure 1 shown); (3) Spraying MQ104 methyl MQ silicone resin [(CH3)3SiO 1 / 2 ] a [SiO 4 / 2 ] b A solvent-based resin coating liquid prepared with 1.5% mass fraction of lipophilic anatase nano-TiO2 powder with a particle size of 15 nm to 20 nm as a film-forming material and a filler is made to adhere and spread on the upper surface of the microbeads, and the film layer is left to dry on the surface for 10 minutes. (4) After the solvent-based silicone resin attached to the upper part of the hollow glass microspheres is initially cured, the glass microspheres are scooped out using a filter, placed in a filter bag, and then dried by centrifugation; taken out and placed in a blast drying oven, and further dried at 120°C for 20 min; finally, heated in an electric furnace and kept at 300°C for 5 min to sinter and cure the film layer, thereby obtaining surface-modified hollow glass microspheres (such as Figure 2 as shown).

[0019] 0.06 g of No. 0 diesel and 299.94 mL of pure water were added to a crystallization dish with a diameter of 10 cm, and the surface-modified hollow glass microbeads prepared in this example were added. After magnetic stirring for 10 minutes, the dish was placed outdoors under natural light for 8 h (Bengbu, November, clear daytime 8:30-16:30). The residual diesel was measured by spectrophotometry, and the diesel removal rate was calculated to be 72.2%. Example

[0020] (1) The hollow glass microspheres prepared by the glass powder method were placed in a rotary vibrating screen 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 / cm 3 Hollow glass microsphere powder; (2) Use anatase-type aqueous titanium dioxide sol (nanocrystalline titanium dioxide particle size is 20nm~30nm) and dilute it with water to a solid content of 3.0% (density is 1.05 g / cm 3 ), add it to a crystallization dish with a diameter of 20 cm to about 1 / 2 of the height, add 0.335g of the hollow glass microspheres obtained in step (1) therein, so that the glass microsphere powder exists on the liquid surface in the form of a single particle layer or a few layers (2 to 3 layers) ( Figure 1 shown); (3) Spray a solvent-based polyacrylate resin coating liquid (without TiO2 filler) prepared with methyl isobutyl ketone as a dispersion medium and 20% by mass of thermoplastic polyacrylate as a film-forming material on the floating hollow glass microspheres, and allow it to adhere and spread on the upper surface of the microspheres. Let it stand for 15 minutes to allow the surface of the film layer to dry; (4) After the solvent-based polyacrylate resin attached to the upper part of the glass microspheres is initially cured, the glass microspheres are scooped out using a filter, placed in a filter bag, and then centrifuged to dry the glass microspheres; taken out and placed in a forced air drying oven at 110°C for 30 min for further drying; finally, heated in an electric furnace at 230°C for 15 min to sinter and solidify the film layer, thereby obtaining surface-modified hollow glass microspheres (such as Figure 2 as shown).

[0021] 0.2 g of No. 0 diesel and 999.8 mL of pure water were added to a crystallization dish with a diameter of 20 cm, and the surface-modified hollow glass microbeads prepared in this example were added. After magnetic stirring for 10 minutes, the dish was placed outdoors under natural light for 8 h (Bengbu, November, clear daytime 8:30-16:30). The residual diesel was measured by spectrophotometry, and the diesel removal rate was calculated to be 50.6%.

Claims

1. A method for preparing surface-modified hollow glass microspheres, characterized in that The steps include: (1) The hollow glass microspheres prepared by the glass powder method were placed in a rotary vibrating screen and sorted to obtain a median diameter D50 of 5 μm to 90 μm and a true density of 0.2 g / cm 3 ~0.6g / cm 3 Hollow glass microsphere powder; (2) adding anatase-type titanium dioxide sol aqueous coating liquid into a container, and then adding the hollow glass microsphere powder obtained in step (1), controlling the glass microsphere powder to exist on the surface of the coating liquid in the form of a single particle layer or 2 to 3 layers; (3) Spraying solvent-based resin coating liquid on the glass beads floating on the surface of the coating liquid. The solvent-based resin coating liquid uses aromatic hydrocarbons, ethers, esters, ketones or halogenated hydrocarbons as the dispersion medium, polyacrylate, polyester, polyurethane, epoxy resin, polysiloxane resin and its composite modified resin as the film-forming material, and anatase-type nano-TiO2 powder with a surface lipophilic particle size distribution of 5nm~20nm as the filler. The amount of filler added is 0~3% of the mass of the coating liquid. After the coating is completed, let the surface stand to dry and initially form a film; (4) After the solvent-based resin attached to the glass microbeads is initially cured, the glass microbeads are scooped out using a filter, placed in a filter bag, and then dried by centrifugation; taken out and placed in a forced air drying oven at 90°C to 150°C for 10 min to 30 min for further drying; finally, heated in an electric furnace at 200°C to 350°C for 5 min to 30 min to sinter and cure the film layer, thereby obtaining surface-modified hollow glass microbeads.

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

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

0.

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

5. The method for preparing surface-modified hollow glass microspheres according to claim 1, characterized in that: In the 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: The density of the titanium dioxide sol aqueous coating liquid in step (2) is not less than 0.75 g / cm 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, methyl ether, ethyl 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 to 7, characterized in that: After step (4) is completed, melt-blown polypropylene oil-absorbing cotton is used to absorb and remove the small amount of oily coating liquid remaining on the surface of the aqueous coating liquid, so as to prepare for the surface modification process of the next batch of hollow glass microspheres.

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