Synthesis and surface properties of submicron barium sulfate particles

摘要

Barium sulfate particles were synthesized in the presence of EDTA at room temperature. X-ray diffrac-tometry (XRD), Fourier transform infrared resonance (FTIR) and scanning electron microscopy (SEM) were used to characterize the structure and morphology of BaSO_4 particles. The effect of the preparation parameters on the particle size distribution and morphology was investigated. The conditional formation constants of Ba-EDTA at different pH values were calculated. The results show that the size and morphology of BaS04 particles can be effectively controlled by adding EDTA in the precipitation process. Among all the operation conditions, the pH value has significant effect on the particle size. The obtained barium sulfate particles are spherical and well dispersed at pH = 9-10. Zeta potentials of BaSO_4 were measured at different pH. The isoelectric point (IEP) of barium sulfate colloid appears at pH 6.92. The model of the solid-solution interface at a particle of BaS04 was presented. The FTIR result indicates that the surface of the prepared BaSO_4 absorbs the functional groups of EDTA, which lower the IEP of the barium sulfate particles.