Production Methods for Nano Barium Sulphate

1.Hydrothermal Method

Mix barium sulfate powder with sodium hydroxide (NaOH),and make them dissolved in deionized water. Then,slowly add polyethylene glycol (PEG) as a surfactant under magnetic stirring. Keep the pH of the solution at around 9 for a certain period of time to allow the formation of barium sulfate crystal nuclei. Finally, transfer the solution to an autoclave,let it react under hydrothermal conditions for about 10 hours to obtain barium sulfate nanoparticles.

2.Direct Precipitation Method

Use sodium dodecyl sulfonate or sodium dodecyl sulfate as a surfactant, prepare nanometer barium sulfate material by direct precipitation method, and make nanometer barium sulfate passivated through water washing process. The final product won't turn yellow at high temperature.

3.Microreactor Method

K2SO4+BaCl2 in microcreactor

Principle：Prepare sulfate solution and barium salt solution at certain concentrations, mix the two solutions,it will be converted to barium sulfate precipitate, barium sulfate powder will be obtained after washing,separation,drying and grinding.
SO42-+Ba2+→BaSO4↓

This method can be used for relatively large-scale continuous synthesis of BaSO4 nanoparticles. In addition, due to the simplicity and ease of use of the components involved in this method, it is expected to be a simple and economical method for synthesizing other nanoparticles with controlled particle size.

4.Microemulsion Method

Two immiscible solvents will be forced to form a uniform and stable emulsion under the action of surfactant molecules, and then solid particles can be precipitated from the emulsion.

By microemulsion method,it's able to produce various forms BaSO4 products with controllable particle size and uniform particle size distribution,the operation method is simple.

However, surfactants have a great influence on the products quality, and the use of organic solvents will break the safety and environmental protection of the process,this makes the cost high and the operation complicated.

5.Anion Exchange Method

6.Surfactant Method

7.Mixed Solvent Method

Using Ba(OH)2·8H2O and H2SO4 as raw materials, nano-barium sulfate ethylene glycol sol can be prepared through solvation, sol reaction and water removal by fractional distillation,and was characterized by transmission electron microscopy. It shows that this method can be used to prepare uniformly dispersed nano-barium sulfate colloids at a higher barium sulfate concentration, with a particle size of 20-30nm. It can be directly used in PET polyester modification production.

8.Vapour Deposition Method

9.Sol-Gel Method

10.EDTA Complex Method

Let the complexing agent ethylenediaminetetraacetic acid (EDTA) react with Ba2+ to generate a relatively stable EDTA-Ba complex,add a precipitant,then the EDTA-Ba complex will slowly decompose, in which it collides with the solution to generate BaSO4 particles.The adsorption of EDTA anions reverses the charge of BaSO4, weakens the surface polarity of BaSO4, and promotes the formation of aggregates through self-assembly and transformation processes.

Spherical BaSO4 with an average particle size of 0.502μm is synthesized under pH = 7,ellipsoidal BaSO4 particles is synthesized  at pH 9-10.The morphological changes caused by pH changes are closely related to the adsorption of monovalent and multivalent anions by the BaSO4 electrical double layer.

When the solution conductivity no longer changes, the particle reaction is completed, and the particles change from spindle to spherical, and the particle size of BaSO4 particles increases with the increase of concentration. With the addition of EDTA-2Na, EDTA-2Na and Ba2+ undergo complexation. EDTA controls the concentration of Ba2+ in the reaction system, preventing it from directly reacting with SO42- to generate a large number of crystals, thereby improving the dispersibility of the powder and generating products with uniform particle size distribution.

The product prepared by this method has a small particle size, EDTA can be recycled, the production process is relatively simple, and the cost is very low. Therefore, it is suitable for industrial production and can also be used to prepare other new nano-scale materials.

11.Ultrasonic Precipitation Method

12.Supergravity Method