Membrane dispersion precipitation method to prepare nanopartials

In this paper, a new method for preparing nanoparticles with membrane dispersion technology was developed by integrating direct chemical precipitation and membrane emulsification. Barium sulfate nanoparticles were prepared with the new method in a membrane dispersion module with a plate microfiltration membrane as dispersion medium. Barium chloride solution and sodium sulfate solution with pure water or 20% ethyl alcohol in water as solvents were selected as the reactants. The influences of the reactant concentrations, two-phase flow rate and membrane pore size were investigated. The morphology of the nanoparticles was characterized by TEM images, and the particle-size distribution was measured. The results showed that the spheric nanoparticles of barium sulfate could be prepared with the new method. The average size was in the range of 20-200 nm. The particles prepared by the new method were much more uniform, compared with those by direct precipitation method. The average size of barium sulfate nanoparticles was decreased with an increase of the concentration and the now rate of sodium sulfate solution quickly. However, those of barium chloride solution had little influence on barium sulfate nanoparticles. The decreasing of the membrane pore size resulted in the decrease of the average size of barium sulfate nanoparticles. And by changing 20% ethyl alcohol in water as solvent instead of pure water, the nanoparticle size was decreased from 70 to 20 nm. (C) 2004 Elsevier B.V. All rights reserved.