CN102167386A - Method for preparing barium sulfate nanoparticles - Google Patents

Abstract

The invention discloses a method for preparing barium sulfate nanoparticles, which belongs to the technical field of chemical material preparation. The sodium sulfate solution is dispersed into a flowing barium sulfide solution or a circulating barium sulfide suspension from a vertical direction through micropores. The sodium sulfate solution is sheared by cross-flow, mixed and reacted to form barium sulfate precipitates, and the reaction product is matured, separated from solid and liquid, washed with water to remove impurities, dried and pulverized to obtain barium sulfate nanoparticles. Using the method of the invention to prepare barium sulfate nanoparticles has low raw material cost, large production capacity, simple operation process, good repeatability and stability, so that the traditional mirabilite-black ash method can enter the production sequence of nanoscale barium sulfate particles. The method can be used to obtain barium sulfate nanoparticles with an average particle size of 35-48nm.

Description

A method for preparing barium sulfate nanoparticles

technical field

The invention belongs to the technical field of chemical material preparation, and in particular relates to a method for preparing barium sulfate nanoparticles, in particular to a method for preparing barium sulfate nanoparticles by a micropore dispersion method utilizing liquid phase cross-flow shearing.

Background technique

Barium sulfate nanoparticles have small size effect and good chemical stability, and are widely used in coatings, plastics, filling materials and additives for paints and other fields. The preparation methods of barium sulfate nanoparticles commonly used at present mainly contain: (1) Glauber's salt-black ash method-using sodium sulfide, barium brine and sodium sulfate as raw materials, first obtain barium sulfide solution or slurry, mix with sodium sulfate solution afterwards, produce Chemical reaction, and then adjust the pH value to the end of the reaction to obtain barium sulfate slurry, and finally obtain the product; (2) Complexation-precipitation method-BaCl ₂ and EDTA solution are used as raw materials, and the two are mixed to prepare Ba ²⁺ -EDTA The complexation system, adjust the complexation system to reach a certain pH value and temperature; then add the pre-prepared Na ₂ SO ₄ solution into the complexation system for reaction, and the reaction product is centrifuged, washed, and dried to obtain nano barium sulfate product. These methods either introduce other reaction components, which increases the difficulty of subsequent separation; or the particle size of the prepared particles is too large, the distribution is wide, and the monodispersity is not good, such as the Glauber's salt-black ash method, the existing particle size of the product of this process is very large Difficult to reach the nanoscale. The reason for this situation is that the microscopic mixing of materials is poor, the transfer process is slow, and the nucleation amount is small and uneven during direct precipitation, which directly affects the quality of the particles.

On the other hand, the micropore dispersion using fluid shear has good performance for both homogeneous and heterogeneous mixing, and the system has high heat and mass transfer efficiency, which helps to solve the problem of poor controllability of rapid reactions due to transfer limitations , which created conditions for a breakthrough in the preparation of barium sulfate nanoparticles by the direct precipitation method.

Contents of the invention

The present invention aims to propose a new method for preparing barium sulfate nanoparticles. Its principle is: what take place in the selected system of the present invention is liquid phase precipitation reaction, and reaction speed is fast, and transfer process is the control step in the preparation process; The system has a higher degree of supersaturation while ensuring the uniformity of mixing, thereby preparing barium sulfate nanoparticles with small particles and uniform distribution.

A method for preparing barium sulfate nanoparticles, the sodium sulfate solution is dispersed into the flowing barium sulfide solution or the circulating barium sulfide suspension from the vertical direction through the micropores, the sodium sulfate solution is sheared by cross-flow, mixed reaction, A barium sulfate precipitate is generated, and the reaction product is matured, separated from solid and liquid, washed with water to remove impurities, dried and pulverized to obtain barium sulfate nanoparticles.

The temperature of the barium sulfide solution or suspension is 10-70°C, and the temperature of the sodium sulfate solution is 10-70°C.

The barium sulfide solution or suspension has a concentration of 0.25-2.5 mol/L, and the sodium sulfate solution has a concentration of 5-45 wt%.

The equivalent diameter of the micropores is 0.2-1000 microns.

The flow velocity of the barium sulfide solution or suspension is 0.2-3m/s, and the flow velocity of the sodium sulfate solution is 0.1-5m/s.

Specifically, the method of the present invention includes the following steps:

(1) prepare barium sulfide solution or barium sulfide suspension;

(2) prepare sodium sulfate solution;

(3) Under pressure, sodium sulfate solution is dispersed into flowing barium sulfide solution or circulating barium sulfide suspension from vertical direction through micropores, sodium sulfate solution is sheared by cross flow, mixed reaction;

(4) The reaction product is ripened, separated from solid and liquid, washed with water to remove impurities, dried, and pulverized (crushed according to industrial standards, that is, 45 μm sieve residue content≤0.5%) to obtain the final barium sulfate nanoparticles.

In step (3), the molar flow rate of the sodium sulfate brought in with the sodium sulfate solution is equal to the molar flow rate of the barium sulfide brought in with the barium sulfide solution.

In step (3), the barium sulfide suspension is continuously circulated until the molar weight of the sodium sulfate brought in with the sodium sulfate solution is equal to the initial barium sulfide molar weight in the barium sulfide suspension.

The beneficial effect of the present invention is: utilize the method of the present invention to prepare barium sulfate nano particle, raw material cost is low, production capacity is big, operation process is simple and easy, repeatability and stability are good, make traditional Glauber's salt-black ash method can enter nanoscale sulfuric acid Production sequence of barium pellets. The method can be used to obtain barium sulfate nanoparticles with an average particle size of 35-48nm.

Detailed ways

The following examples can enable those skilled in the art to understand the present invention more comprehensively, but do not limit the present invention in any way.

Example 1:

At 70°C, prepare 1000 mL of a barium sulfide suspension with a molar concentration of 2.5 mol/L and 800 g of a 45% sodium sulfate solution. Under the action of pressure difference, the sodium sulfate solution passes through micropores with an equivalent diameter of 200 microns at a flow rate of 0.5m/s and mixes with the barium sulfide suspension flowing in a cross-flow cycle with a flow rate of 1m/s to generate sulfuric acid. Barium is precipitated, and the reaction is cycled to the stoichiometric ratio. The product is matured, separated from solid and liquid, washed with water to remove impurities, dried and pulverized to obtain final barium sulfate particles with an average particle diameter of 48nm.

Example 2:

At 50°C, prepare 1000 mL of barium sulfide solution with a molar concentration of 1.5 mol/L and 720 g of a 30% sodium sulfate solution. Under the action of pressure difference, the sodium sulfate solution passes through the micropores with an equivalent diameter of 200 microns at a flow rate of 5 m/s and mixes with the barium sulfide solution that flows in a cross flow with a flow rate of 3 m/s, and reacts to form barium sulfate precipitates. The product is matured, separated from solid and liquid, washed with water to remove impurities, dried and pulverized to obtain final barium sulfate particles with an average particle diameter of 43nm.

Example 3:

At 20°C, prepare 1000 mL of a barium sulfide suspension with a molar concentration of 0.5 mol/L and 720 g of a 10% sodium sulfate solution. Under the action of pressure difference, the sodium sulfate solution passes through micropores with an equivalent diameter of 600 microns at a flow rate of 0.1 m/s and mixes with barium sulfide suspension with a flow rate of 0.3 m/s for cross-flow circulation, and the reaction forms Barium sulfate is precipitated, and the reaction is cycled to the stoichiometric ratio. The product is matured, separated from solid and liquid, washed with water to remove impurities, dried and pulverized to obtain final barium sulfate particles with an average particle diameter of 40nm.

Example 4:

At 10°C, prepare 1000 mL of a barium sulfide solution with a molar concentration of 0.25 mol/L and 720 g of a 5% sodium sulfate solution. Under the action of pressure difference, the sodium sulfate solution passes through micropores with an equivalent diameter of 0.2 microns at a flow rate of 0.2 m/s and mixes with the barium sulfide solution that flows in a cross-flow with a flow rate of 0.2 m/s, and reacts to form barium sulfate precipitates . The product is matured, separated from solid and liquid, washed with water to remove impurities, dried and pulverized to obtain final barium sulfate particles with an average particle diameter of 35nm.

Example 5:

At 40°C, prepare 1000 mL of barium sulfide solution with a molar concentration of 1.0 mol/L and 720 g of a 20% sodium sulfate solution. Under the action of pressure difference, the sodium sulfate solution passes through micropores with an equivalent diameter of 200 microns at a flow rate of 0.5m/s and mixes with the barium sulfide solution with a flow rate of 1m/s as a cross-flow flow, and reacts to form barium sulfate precipitates. The product is matured, separated from solid and liquid, washed with water to remove impurities, dried and pulverized to obtain final barium sulfate particles with an average particle diameter of 37nm.

The above is only a preferred embodiment of the present invention, but the scope of protection of the present invention is not limited thereto. Any person skilled in the art within the technical scope disclosed in the present invention can easily think of changes or Replacement should be covered within the protection scope of the present invention. Therefore, the protection scope of the present invention should be determined by the protection scope of the claims.

Claims (9)

1. A method for preparing barium sulfate nanoparticles is characterized in that: sodium sulfate solution is dispersed into flowing barium sulfide solution or the barium sulfide suspension of circulating flow through micropore from vertical direction, and sodium sulfate solution is cross-flowed Shearing and mixing reactions generate barium sulfate precipitation, and the reaction product is post-processed to prepare barium sulfate nanoparticles. 2. The method according to claim 1, characterized in that: the post-treatment comprises the following steps: ripening, solid-liquid separation, washing to remove impurities, drying, and crushing. 3. The method according to claim 1, characterized in that: the temperature of the barium sulfide solution or suspension is 10-70°C, and the temperature of the sodium sulfate solution is 10-70°C. 4. The method according to claim 1, characterized in that: the concentration of the barium sulfide solution or suspension is 0.25 to 2.5 mol/L, and the concentration of the sodium sulfate solution is 5 to 45 wt%. 5. The method according to claim 1, characterized in that: the equivalent diameter of the micropores is 0.2-1000 microns. 6. The method according to claim 1, characterized in that: the flow velocity of the barium sulfide solution or suspension is 0.2 to 3 m/s, and the flow velocity of the sodium sulfate solution is 0.1 to 5 m/s. 7. The method according to claim 1, characterized in that comprising the steps of: (1) prepare barium sulfide solution or barium sulfide suspension; (2) prepare sodium sulfate solution; (3) Under pressure, sodium sulfate solution is dispersed into flowing barium sulfide solution or circulating barium sulfide suspension from vertical direction through micropores, sodium sulfate solution is sheared by cross flow, mixed reaction; (4) The reaction product is matured, separated from solid and liquid, washed with water to remove impurities, dried and pulverized to obtain barium sulfate nanoparticles. 8. The method according to claim 7, characterized in that: in step (3), the molar flow rate of the sodium sulfate brought in with the sodium sulfate solution is equal to the molar flow rate of the barium sulfide brought in with the barium sulfide solution. 9. method according to claim 7, it is characterized in that: in step (3), barium sulfide suspension is constantly circulated, until the molar weight of the sodium sulfate that brings into with sodium sulfate solution is the same as the initial value in barium sulfide suspension. The molar amount of barium sulfide is equal.