Abstract
Scale formation induced by less soluble salts in sea-water is a common problem to be solved ina desalination plant. Barium sulphate and strontium sulphate, which have small solubilities in seawater, are thought to be scale components on a membrane in an RO desalination plant or on abrine heater and an evaporator in a multi-stage flash evaporation-type desalination plant. In thisstudy, equilibrium distributions of barium sulphate and strontium sulphate in sea-water wereexamined. The amount of barium from 5 ppb to 3 ppm and that of strontium from 2 ppb to 40 ppmcould be determined by using an inductively coupled plasma emission spectrophotometer (ICP). The relation between a solubility product and an ion strength of synthetic sea-water was obtainedto estimate the degree of saturation. Based on this relationship, a calculated apparent solubilityproduct of barium sulphate in natural sea-water agreed with that obtained from an equilibrium distribution experiment.
