The kinetics of precipitation of barium sulfate from aqueous solution

Abstract The rate of precipitation of barium sulfate has been investigated using the conductimetric technique. In direct mixing experiments all but a negligible number of precipitation nuclei form during the mixing process, probably in small local volume elements where the supersaturation is larger than it is after complete homogenization. In the earliest stages of precipitation the rate of linear growth of barium sulfate crystals is independent of their size and apparently limited by a process occurring at the crystal-solution interface. After the crystals reach a certain size their growth rate becomes limited by diffusion. It is shown that the assumption of Christiansen and Nielsen [2], that the reciprocal of the time of appearance of turbidity is directly proportional to the homogeneous nucleation frequency, is probably not valid.