Preparation method of high-dispersity g-C3N4/TiO2 photocatalyst inorganic hydrosol

A highly dispersible gC₃N₄/T i O2 photocatalyst inorganic hydrosol preparation method technical field

[0001] The present invention relates to a stable highly dispersed nano gC₃N4/Ti0₂Preparation method of photocatalyst inorganic hydrosol. It belongs to the field of building coating materials.

Background technique

[0002] Nano-TiO2 exhibits unique optoelectronic properties due to its unique surface effect, small size effect, quantum effect and macroscopic quantum tunneling effect. Its chemical properties are stable, non-toxic and cheap, unique color effect, photocatalysis and ultraviolet shielding functions, so that it has broad application prospects in coatings, cosmetics, wastewater treatment, sterilization and environmental protection. However, the nano-TiO2 has a large specific surface area and high surface energy, and particle agglomeration is prone to occur during use, which seriously affects its application. Therefore, seeking an effective dispersion method is the key to overcome the agglomeration of nano-TiO2 particles and expand the application field. In recent years, the research on the dispersion of nano-TiO2 particles has mostly used organic surface dispersants to modify nano-TiO2. By generating electrostatic stability and steric hindrance, it can improve its dispersion stability in water, and its dispersion effect is better. Low viscosity suspension. However, due to the non-selectivity of TiO2 photocatalytic oxidation, it is easy to cause corrosion to the organic components (substrate) in the system during use. Therefore, how to prepare a highly stable, highly dispersed, and low-viscosity suspension by controlling the colloidal properties of the nano-TiO2 powder in the medium, the pH value of the suspension, and the type of dispersant, the selection and dosage of the dispersant is an important key factor.

[0003] At present, TiO2 hydrosol mainly has two problems. (1) TiO2 is not doped and modified, and can only be excited by ultraviolet light to produce a self-cleaning effect, and it is difficult to use a large amount of visible light in sunlight; (2) sol The preparation mainly uses organic titanium sources: butyl titanate, titanium isopropoxide, etc., and the preparation of the sol is achieved by hydrolysis. The cost of raw materials is high, the gas is easily separated after film formation, and the reaction time is long. The preparation efficiency is low, and organic solvents are also harmful to the human body and the environment. Direct coating of Ti02 acid sol will cause cement substrates. damage. The present invention utilizes low-cost preparation of graphite phase carbon nitride (gC₃N₄) And commercial nano-TiO2 as raw materials, using mechanochemical methods to prepare gC with visible light activity₃N₄/TiO₂Photocatalyst, and on this basis, a highly dispersible gC is prepared₃N₄/TiO₂The near-neutral inorganic hydrosol of the photocatalyst provides a good solution for solving the above problems, and there is no relevant literature report at present.

Summary of the invention

[0004] In view of the current technical difficulties in preparing well-dispersed nano-TiO2-based stable hydrosols, the purpose of the present invention is to provide a simple, low-cost, high-stability, high-dispersion, modified TiO2 neutral hydrosol preparation method.

[0005] Preparation of gC with high stability, high dispersion and suitable viscosity₃N₄/TiO₂Suspension is the key to colloidal molding. In order to achieve the above goals, by controlling the colloidal properties of the powder in the medium, the type and amount of dispersant, the pH value and the mixing method, etc., the Ti02-based powder is dispersed in water. Research to achieve high dispersion and high stability gC₃N₄/Ti0₂zK sol preparation.

[0006] In order to achieve the purpose of the present invention, the technical solutions are as follows:

[0007] (1) Commercial nano-titanium dioxide (anatase) is conjugated to gC₃N₄After the surface hybridization modification, the visible light active gC is prepared₃N₄/TiO₂Photocatalyst

[0008] (2) The dispersant sodium hexametaphosphate and sodium silicate were sequentially added to 100ml of water, and the dispersant was added in an amount of 0.1~

0.5wt%, stirring and dissolving completely;

[0009] (3) In step (2), gC is gradually added to the above-mentioned solution₃N₄/TiO₂The photocatalyst powder is added in an amount of 1~3wt%, and then 1~3wt% of H2O2 solution is added dropwise, shear emulsification, and peptization process;

[0010] (4) Adjust the pH of the suspension to 7~8 with hydrochloric acid or sodium hydroxide solution, and continue to stir and disperse to obtain gC₃N₄/

Ti02 photocatalyst hydrosol.

[0011] The present invention uses modified g-C3N₄/Ti0₂Photocatalyst was used as raw materials, and inorganic dispersants sodium hexametaphosphate and sodium silicate, and Hui 2 were used as peptizers to prepare visible-light catalytically active g-C3N"TiO2 photocatalyst hydrosol. Tests proved that the prepared gC₃N₄/TiO₂The active components of the hydrosol photocatalyst are evenly distributed, and the sol has good stability, and will not precipitate after being stored for a long time (more than 3 months). The synthetic hydrosol is close to neutrality, strong hydrophilicity, and low viscosity, can be well coated on the surface of buildings, and has good photocatalytic ability and self-cleaning performance, which provides a basis for self-cleaning on the surface of building materials.

[0012] The innovations of the present invention are: 1. Water is used as a solvent, no organic dispersants and solvents are used, and the system does not contain organic components, which reduces costs, is environmentally friendly and safe, and is more suitable for larger-scale production. 2. The order of adding the components of the suspension system is: first add the two-component dispersants sodium hexametaphosphate and sodium silicate, stir and dissolve completely, then gradually add gC₃N₄/TiO₂For photocatalyst powder, add a small amount of peptizer to produce 02 at the end; in this process, the type and amount of dispersant, pH value and order of addition will all affect the dispersion of Ti02-based powder in water. The dispersion stability of nanoparticles is the key to their function. This method uniformly disperses nano-sized modified titanium dioxide particles in a neutral aqueous solution, and cooperates with a mechanical dispersion method to speed up the peptization process and shorten the dispersion time. The sol is stable and does not agglomerate. The operation is simple, the system is stable and the dispersion effect is long-lasting, which is a convenient and quick way to prepare gC₃N₄/TiO₂A new method of hydrosol, using this hydrosol to form a film on the surface of the substrate, without high temperature treatment, it can have good visible light catalytic activity, and has a good function of removing indoor V0C.

Description of the drawings

[0013] FIG. 1 is the measurement result of the contact angle of the sample of the present invention, in the figure, AH₂0,B-lwt%-gC₃N4/Ti0₂Hydrosol, C3wt% -g-CaNVTiOz hydrosol;

[0014] FIG. 2 is a transmission electron microscope photo of the sample of the present invention, in the figure, a-TiO2, bg-C3N4, c-3wt%-g-C3N4/TiO2, d3wt%-gC₃N₄/T i O2 high-resolution transmission electron microscope photo;

[0015] Figure 3 is the XRD pattern and Raman spectrum of the sample of the present invention, the center of the figure is the XRD pattern of the sample of the present invention and the Raman spectrum of the sample of the present invention; e Figure 1 is gC₃N₄, 2 is 5wt%-gC₃N₄/TiO₂,3 is TiCh; f in the figure, 1 is 3wt%-gC₃N₄/ TiCh, 2 is TiCh;

[0016] FIG. 4 is the ultraviolet-visible diffuse reflectance spectrum and AC impedance spectrum of the sample of the present invention. In the figure, the ultraviolet-visible diffuse reflectance spectrum of the sample of the present invention is shown in g, where 1 is 3wt%-g-C3N4/TiO2, and 2 is TiO2; h-AC impedance spectroscopy of the sample of the present invention;

[0017] Figure 5 is the photocatalyst degradation of methylene blue dye catalytic activity of the samples of the present invention, in the figure, ten under ultraviolet light (15W mercury lamp) photocatalyst degradation of methylene blue dye catalytic activity under visible light (500W magic emanation lamp, 420nm filter) Photocatalyst degradation of methylene blue dye catalytic activity.

Detailed ways

[0018] In order to better illustrate the present invention, examples are as follows:

Example 1

[0020] The high dispersibility g-C3N₄/TiO₂The preparation method of photocatalyst inorganic hydrosol is realized by the following method:

[0021] (1) Commercial nano-titanium dioxide (anatase) is conjugated to gC₃N₄After the surface hybridization modification, the prepared

Visible light active gC₃N₄/TiO₂Photocatalyst

[0022] (2) Add the two-component dispersant sodium hexametaphosphate and sodium silicate in order in 100ml water, and the added amount of the dispersant is

0.1~0.5wt%, dissolve completely after stirring for 30min;

[0023] (3) In step , gradually add g-C3N"TiO2 photocatalyst powder to the above solution, the addition amount is 1~3wt%, 1~3wt% of H2O2 solution is added dropwise, shear emulsification 10min, and peptization process;

[0024] (4) Adjust the pH of the suspension to 7~8 with hydrochloric acid or sodium hydroxide solution, and continue to stir and disperse for 30 min to obtain gC₃N₄/TiO₂Photocatalyst hydrosol.

[0025] The test results are shown in Tables 1, 2, 3.

[0026] Table 1 Apparent viscosity of hydrosol samples

[0027]

<td>sample name</td><td>The present invention 3wt%-gC₃N₄/TiO₂</td><td>The present invention lwt% -g-C3N4/TiO2</td><td>h₂o</td>

<td>Viscosity (mPa · S)</td><td>20 〜30</td><td>10 〜16</td><td>10 〜14</td>

[0028] Table 1 Main physical properties of photocatalyst samples

<td>sample name</td><td>Appearance</td><td>Average: Grain. Diameter (D/nm)</td><td>Specific surface area (Sbet/ib²·^¹)</td>

<td>Nano TiO₂</td><td>White powder</td><td>10</td><td>10.3</td>

<td>3wt%-C3N4/Ti6 photocatalyst of the present invention</td><td>Light yellow powder</td><td>〔25</td><td>12.5</td>

[0030] Table 3 Main performance indicators of hydrosol

<td>sample name</td><td>Settlement test</td><td>pH value</td><td>Zeta potential</td><td>Adhesion</td><td>Photocatalytic activity</td><td>Corrosion of Substrate</td>

<td>Hydrosol of the present invention</td><td>&gt;3 months</td><td>neutral</td><td>Absolutely large</td><td>Strong</td><td>Visible light</td><td></td>

<td>Commercially available TiCh hydrosol</td><td>About 30 days</td><td>Weakly alkaline</td><td>The absolute value is larger</td><td>Stronger</td><td>Ultraviolet light</td><td>rw</td>