CN110256874A - The process of zirconium silicon compound adhesive cyst membrane coated red schorl type titanium dioxide - Google Patents

Abstract

The invention belongs to the technical field of coated titanium dioxide production, and discloses a process method for coating rutile-type titanium dioxide with a zirconium-silicon capsule film. The process conditions include a slurry concentration of 300 g/L and a content of 0.1 ‑0.5%, wherein the technological conditions for coating rutile-type titanium dioxide with zirconia are: water bath temperature is 40-60°C, zirconia coating amount is 1-3wt%, reaction pH is 3-6, silicon oxide is rutile-type The process conditions of titanium dioxide coating are: the water bath temperature is 70-90°C, the coating amount of silicon oxide is 1-2wt%, the reaction pH is 8-10, and zirconia and silicon oxide form a dense and uniform composite capsule nanometer on the surface of titanium dioxide. membrane. The invention can coat the surface of the titanium dioxide particles with a dense zirconia/silicon oxide composite capsule nano-film protective layer, thereby reducing the surface activity of the titanium dioxide and increasing the dispersibility and weather resistance of the titanium dioxide.

Description

Process method for coating rutile titanium dioxide with zirconium-silicon composite capsule film

technical field

The invention belongs to the technical field of coated titanium dioxide production, and more specifically relates to a process method for coating rutile-type titanium dioxide with a zirconium-silicon composite capsule film.

Background technique

Titanium dioxide is widely used in pigments such as coatings, rubber, plastics, paper and other industries due to its stable chemical properties and good whiteness, tinting strength, hiding power and heat resistance. It is also used as a photocatalyst, photoelectric cell, etc. , UV shielding agent, etc. are widely used. The surface of titanium dioxide without surface treatment is generally covered by polar groups such as (-OH), so titanium dioxide is easy to agglomerate due to polar adsorption or moisture absorption, and it is difficult to disperse in other systems. Therefore, it is very important to coat titanium dioxide. With the rapid development of the national economy, the demand for titanium dioxide is also rising. Although my country's titanium dioxide production capacity is large, the product quality is not high, and there is a big gap between the products of well-known foreign companies. Therefore, it is necessary to develop a method capable of producing high-quality titanium dioxide.

There are many factors affecting the surface modification of titanium dioxide, such as the choice of coating agent, addition amount, addition sequence, addition speed, pH value, temperature, reaction time, etc., all have a great impact on the properties of the powder.

In the current technology, it is easy to form island-shaped particle coating on the surface of TiO ₂ , and it cannot form a continuous dense film. The weather resistance of TiO ₂ is poor, which limits the application range of TiO ₂ and cannot be used for the preparation of high-end products.

Contents of the invention

The object of the present invention is to provide a titanium dioxide powder whose surface is coated with a protective layer of zirconium oxide and silicon oxide, so that the coated titanium dioxide powder has better dispersibility and weather resistance.

The present invention is accomplished through the following technical solutions:

A process method for coating rutile titanium dioxide with a zirconium-silicon composite capsule film, comprising the following steps:

1) Take rutile-type titanium dioxide, add deionized water, constant volume, and form a slurry;

2) adding an appropriate amount of sodium tripolyphosphate solution to the slurry, and ultrasonically dispersing to obtain a dispersion;

3) At a certain water bath temperature, add zirconium sulfate solution and sodium hydroxide solution to the dispersion at the same time, adjust the feeding rate to control the pH value, and stir to react;

4) After the feeding is completed, carry out the first aging;

5) After aging, adjust the water bath temperature and pH value; at the water bath temperature, add sodium silicate solution and sulfuric acid solution to the dispersion at the same time, adjust the feeding rate to maintain the pH value, and stir for reaction;

6) After the feeding is completed, aging is carried out for the second time; the coated slurry is obtained;

7) Suction filtration is performed on the obtained coated slurry, and the filter cake is washed;

8) The obtained filter cake is dried and ground to obtain rutile-type titanium dioxide coated with zirconium-silicon composite;

In step 1), the concentration of the slurry is 300g/L;

In step 2), the added amount of the sodium tripolyphosphate is 0.1-0.5% relative to the mass ratio of the rutile titanium dioxide;

In step 2), the ultrasonic dispersion time is 30min;

In step 3), the temperature of the water bath is 40-60°C;

In step 3), the pH value is 3-6;

In step 3), the added amount of zirconium sulfate is 1-3% of the mass of titanium dioxide powder according to the content of zirconium oxide, and the feeding time is 1h;

In step 4), the aging time for the first time is 2h, and the stirring rate is kept during the aging process, the temperature of the water bath, and the pH value are constant;

In step 5), the temperature of the water bath is 70-90°C; the pH value is 8-10;

In step 5), the amount of sodium silicate added is 1-2% of the mass of titanium dioxide powder according to the content of silicon oxide, and the addition time is 1h;

In step 6), the aging time for the second time is 2h, and the stirring rate is kept during the aging process, the temperature of the water bath, and the pH value are constant;

In step 7), the filter cake is washed to neutrality;

In step 8), the drying is carried out at 105° C. for 24 hours.

The present invention has following advantage and effect:

Using the above scheme, the surface of titanium dioxide particles can be coated with a dense and uniform capsule-shaped zirconium oxide/silicon oxide protective layer, thereby reducing the surface activity of titanium dioxide, increasing the dispersibility and weather resistance of titanium dioxide, and surface functionalization improves the application of _TiO2 field. The method of the invention is simple, easy to implement, low in cost and pollution-free.

Description of drawings

Accompanying drawing 1 is the TEM image of the uncoated sample when the transmission electron microscope is magnified by 800,000 times.

Accompanying drawing 2 is the TEM image of zirconia-coated pH 3 and coating amount of 1%; silicon oxide-coated pH 8 and coating amount of 1% when the transmission electron microscope is magnified by 800,000 times.

Accompanying drawing 3 is the TEM image of zirconia-coated pH 4 and coating amount of 2%; silicon oxide-coated pH 9 and coating amount of 1% when the transmission electron microscope is magnified by 800,000 times.

Accompanying drawing 4 is the TEM image of zirconia-coated pH 6 and coating amount of 3%; silicon oxide-coated pH 10 and coating amount of 2% when the transmission electron microscope is magnified by 800,000 times.

Accompanying drawing 5 is the TEM image of zirconia-coated pH 4, coating amount 2%; silicon oxide-coated pH 9.5, coating amount 1% when the transmission electron microscope is magnified 800,000 times.

Accompanying drawing 6 is the TEM image of zirconia-coated pH of 9, coating amount of 2%; silicon oxide-coated pH of 9.5, coating amount of 1% when the transmission electron microscope is magnified by 800,000 times.

Accompanying drawing 7 is the comparison diagram of photocatalytic activity of uncoated sample, different examples and comparative examples to methylene blue solution after ultraviolet light irradiation for 2 hours.

Detailed ways

Below in conjunction with example and accompanying drawing, the present invention is further described.

Example 1

Take 150g of rutile titanium dioxide, add 500mL of deionized water to make a 300g/L slurry, add 15mL of sodium tripolyphosphate solution with a concentration of 10g/L as a dispersant to make a suspension; ultrasonically disperse for 30min to obtain a dispersion Move to 40 ℃ in the constant temperature water bath, adjust pH to 3, under stirring condition, add the zirconium sulfate coating agent that mass fraction is 10% with peristaltic pump, until the ZrO in the mixed slurry _The content is equal to the mass of titanium dioxide powder 1% of NaOH solution, and use another peristaltic pump to add NaOH solution with a mass fraction of 10%, maintain the pH value at 3, and control the feeding time at about 1h. After the feeding is completed, keep the water bath temperature and stirring rate for aging for 2h; to 80°C, and adjust the pH to 8; under stirring conditions, add a sodium silicate coating agent with a mass fraction of 10% with a peristaltic pump until the _SiO2 content in the mixed slurry is 1% of the mass of titanium dioxide powder, and use another Add a peristaltic pump with a mass fraction of 10% H ₂ SO ₄ solution to maintain a pH value of 8. The feeding time is controlled at about 1 hour. After the feeding is completed, keep the temperature of the water bath and the stirring rate for aging for 2 hours; filter and wash the resulting slurry , drying and grinding to obtain samples.

The surface coating of the prepared sample was analyzed by TEM, and the results are shown in Figure 2. It can be found from Figure 2 that under the conditions of this example, a uniform and dense zirconia/silicon oxide composite nanofilm with capsule structure is formed on the surface of the titanium dioxide particles, the thickness of the composite nanocapsule film is 3.0nm, and the coating rate is 100%.

Example 2

Take 150g rutile titanium dioxide, add 500mL deionized water to make a 300g/L slurry, add 30mL sodium tripolyphosphate solution with a concentration of 10g/L as a dispersant to make a suspension; ultrasonically disperse for 30min to obtain a dispersion Move to 50 DEG C in the constant temperature water bath, adjust pH to 4, under stirring condition, add the zirconium sulfate coating agent of mass fraction 10% with peristaltic pump, until the ZrO in the mixed slurry The content is ₁ % of the titanium dioxide powder quality 2%, and use another peristaltic pump to add NaOH solution with a mass fraction of 10%, maintain the pH value at 4, and control the feeding time at about 1h. After the feeding is completed, keep the water bath temperature and stirring rate for aging for 2h; 90°C, adjust the pH to 9; under stirring conditions, use a peristaltic pump to add a sodium silicate coating agent with a mass fraction of 10% until the _SiO2 content in the mixed slurry is 1% of the mass of titanium dioxide powder, and use another A peristaltic pump was used to add _H2SO4 solution with a mass fraction of ₁₀ % to maintain a pH value of 9, and the feeding time was controlled at about 1 h. After the feeding was completed, the temperature of the water bath and the stirring rate were maintained for aging for 2 h; the resulting slurry was filtered, washed, Dry and grind to obtain samples.

The surface coating of the prepared sample was analyzed by TEM, and the results are shown in Figure 3. It can be found from Figure 3 that under the conditions of this example, a uniform and dense zirconia/silicon oxide composite nanofilm with a capsule structure is formed on the surface of the titanium dioxide particles, the thickness of the composite nanocapsule film is 3.6nm, and the coating rate is 100%.

Example 3

Take 150g rutile titanium dioxide, add 500mL deionized water to make a 300g/L slurry, add 75mL sodium tripolyphosphate solution with a concentration of 10g/L as a dispersant to make a suspension; ultrasonically disperse for 30min to obtain a dispersion Move to 60 ℃ constant temperature water bath, adjust pH to 6, under stirring condition, add the zirconium sulfate coating agent that mass fraction is 10% with peristaltic pump, until the ZrO in the mixed slurry _The content is the mass of titanium dioxide powder 3%, and use another peristaltic pump to add a NaOH solution with a mass fraction of 10%, to maintain a pH value of 6, and the feeding time is controlled at about 1h. After the feeding is completed, keep the water bath temperature and stirring rate for aging for 2h; to 70°C, and adjust the pH to 10; under stirring conditions, use a peristaltic pump to add a sodium silicate coating agent with a mass fraction of 10% until the _SiO2 content in the mixed slurry is 2% of the mass of titanium dioxide powder, and use another Add a peristaltic pump with a mass fraction of 10% H ₂ SO ₄ solution, maintain the pH value at 10, and control the feeding time at about 1 hour. After the feeding is completed, keep the temperature of the water bath and the stirring rate for aging for 2 hours; filter and wash the resulting slurry , drying and grinding to obtain samples.

The surface coating of the prepared sample was analyzed by TEM, and the results are shown in Figure 4. It can be seen from Figure 4 that under the conditions of this example, a uniform and dense zirconia/silicon oxide composite nanofilm with a capsule structure is formed on the surface of the titanium dioxide particles, the thickness of the composite nanocapsule film is 4.7nm, and the coating rate is 100%.

Example 4

Take 150g of rutile titanium dioxide, add 500mL of deionized water to make a 300g/L slurry, add 15mL of sodium tripolyphosphate solution with a concentration of 10g/L as a dispersant to make a suspension; ultrasonically disperse for 30min to obtain a dispersion Move to 50 ℃ constant temperature water bath, adjust pH to 4, under stirring condition, add the zirconium sulfate coating agent that mass fraction is 10% with peristaltic pump, until the ZrO in the mixed slurry _The content is the mass of titanium dioxide powder 2%, and use another peristaltic pump to add a NaOH solution with a mass fraction of 10%, to maintain a pH value of 4, and the feeding time is controlled at about 1h. After the feeding is completed, keep the water bath temperature and stirring rate for aging for 2h; to 80°C, and adjust the pH to 9.5; under stirring conditions, add a sodium silicate coating agent with a mass fraction of 10% with a peristaltic pump until the _SiO2 content in the mixed slurry is 1% of the mass of titanium dioxide powder, and use another Add a peristaltic pump with a mass fraction of 10% H ₂ SO ₄ solution to maintain a pH value of 9.5, and control the feeding time at about 1 hour. After the feeding is completed, keep the temperature of the water bath and the stirring rate for aging for 2 hours; filter and wash the obtained slurry , drying and grinding to obtain samples.

The surface coating of the prepared sample was analyzed by TEM, and the results are shown in Figure 5. It can be seen from Fig. 5 that under the conditions of this example, a uniform and dense zirconia/silicon oxide composite nanofilm with a capsule structure is formed on the surface of the titanium dioxide particles, the thickness of the composite nanocapsule film is 3.7nm, and the coating rate is 100%.

Comparative example 1

Take 150g of rutile titanium dioxide, add 500mL of deionized water to make a 300g/L slurry, add 15mL of sodium tripolyphosphate solution with a concentration of 10g/L as a dispersant to make a suspension; ultrasonically disperse for 30min to obtain a dispersion Move to 50 ℃ constant temperature water bath, adjust pH to 9, under stirring condition, add the zirconium sulfate coating agent that mass fraction is 10% with peristaltic pump, until the ZrO in the mixed slurry _The content is the mass of titanium dioxide powder 2%, and use another peristaltic pump to add NaOH solution with a mass fraction of 10%, to maintain the pH value of 9, and the feeding time is controlled at about 1h. After the feeding is completed, keep the water bath temperature and stirring rate for aging for 2h; to 80°C, and adjust the pH to 9.5; under stirring conditions, add a sodium silicate coating agent with a mass fraction of 10% with a peristaltic pump until the _SiO2 content in the mixed slurry is 1% of the mass of titanium dioxide powder, and use another Add a peristaltic pump with a mass fraction of 10% H ₂ SO ₄ solution to maintain a pH value of 9.5, and control the feeding time at about 1 hour. After the feeding is completed, keep the temperature of the water bath and the stirring rate for aging for 2 hours; filter and wash the obtained slurry , drying and grinding to obtain samples.

The surface coating of the prepared sample was analyzed by TEM, and the results are shown in Figure 6. It can be seen from Fig. 6 that under the conditions of this example, an island-shaped zirconia/silicon oxide composite nanofilm is formed on the surface of the titanium dioxide particles, the thickness of the composite nanofilm is 3.9nm, and the coating rate is 75%.

Example 5

Photocatalytic Activity Experiment

Experimental method: Prepare a 10mg/L methylene blue solution and place it in a glass beaker, add a certain amount of surface-coated rutile titanium dioxide to form a 50mg/L suspension. Place under a certain intensity xenon lamp for irradiation, and continue electromagnetic stirring. After 2 hours, take 10 mL of sample. After centrifugation, take the supernatant of the suspension for measurement by ultraviolet spectrophotometer. The experimental results are shown in Figure 7.

It can be seen from Figure 7 that the coated sample can effectively reduce the degradation rate of methylene blue in the solution, indicating that after the surface of titanium dioxide is coated with zirconia/silicon oxide composite nanofilm, its photocatalytic activity is suppressed, which is beneficial to improve its weather resistance sex.

Claims (10)

1. The process of coating rutile titanium dioxide with zirconium-silicon composite capsule film, is characterized in that, comprises the following steps: 1) Take rutile-type titanium dioxide, add deionized water, constant volume, and form a slurry; 2) adding an appropriate amount of sodium hexametaphosphate solution to the slurry, and ultrasonically dispersing to obtain a dispersion; 3) At a certain water bath temperature, add zirconium sulfate solution and sodium hydroxide solution to the dispersion at the same time, adjust the feeding rate to control the pH value, and stir to react; 4) After the feeding is completed, carry out the first aging; 5) After aging, adjust the water bath temperature and pH value; at the water bath temperature, add sodium silicate solution and sulfuric acid solution to the dispersion at the same time, adjust the feeding rate to maintain the pH value, and stir for reaction; 6) After the feeding is completed, aging is carried out for the second time; the coated slurry is obtained; 7) Suction filtration is performed on the obtained coated slurry, and the filter cake is washed; 8) The obtained filter cake is dried and ground to obtain rutile-type titanium dioxide coated with zirconium-silicon composite. 2. The process according to claim 1, characterized in that, in step 1), the concentration of the slurry is 300g/L. 3. process according to claim 1, is characterized in that, step 2) in, the add-on of described sodium hexametaphosphate is 0.1-0.5% relative to the mass ratio of rutile type titanium dioxide; The time is 30 minutes. 4. The process according to claim 1, characterized in that, in step 3), the temperature of the water bath is 40-60° C.; the pH value is 3-6; the zirconium sulfate addition is according to the content of zirconium oxide. The mass of titanium dioxide powder is 1-3%, and the feeding time is 1h. 5. The process according to claim 1, characterized in that, in step 4), the aging time for the first time is 2h, and the stirring rate is kept during the aging process, the temperature of the water bath, and the pH value are constant. 6. The process according to claim 1, characterized in that, in step 5), the temperature of the water bath is 70-90° C.; the pH value is 8-10. 7. The process according to claim 1, characterized in that, in step 5), the amount of sodium silicate added is 1-2% of the mass of titanium dioxide powder according to the content of silicon oxide, and the feeding time is 1h. 8. The process according to claim 1, characterized in that, in step 6), the aging time for the second time is 2h, and the stirring rate is kept during the aging process, and the temperature of the water bath and the pH value are constant. 9. The process according to claim 1, characterized in that, in step 7), the filter cake is washed to neutrality. 10. The process according to claim 1, characterized in that, in step 8), the drying is carried out at 105° C. for 24 hours.