Determination of Effects of Some Parameters On The Sedimentation Rates Of Strontium And Barium Carbonates In Aqueous Medium

In recent times sedimentation data have become increasingly relevant in modeling sedimentation operations such as filtration, fluidization, two-phase flow operations and in environmental engineering. In this study, the effects of reactants concentrations and size of settling vesselson the sedimentation rates of strontium and barium carbonates, in aqueous medium, were studied by a modified approach of the ‘isolation method’. We systematically varied the interactions and chemical environment of the resulting precipitates by successively varying the concentrations of ions in excess in the mixtures. This variation affected the kinetic behaviour of the precipitates in the suspension medium and the results obtained showed a relationship between the sedimentation behaviour of the insoluble metal carbonates and the ionic concentrations of the reactants. Initial settling behaviour also showed that, for the colloidal precipitates, increasing excess of metal ions in reaction mixture had more significant effect than increasing excess carbonate ions. When the metal ion concentration was varied, +0.21 and -0.67 were obtained as sedimentation order and 1.01 x 10 cm sM and 2.32 x 10 cm sM were also obtained as sedimentation rate constants for strontium and barium carbonates respectively. On the other hand, when the carbonate ion concentration was varied, +0.35 and -1.01 were obtained as sedimentation orders and 1.36 x 10 cm sM and 3.81 x 10 cm sM were also obtained as sedimentation rate constants for strontium and barium carbonates respectively. The results of the sedimentation rates of barium carbonate precipitates measured in cylinders of varying sizes showed that the rate correlated positively (r = 0.9056) with the internal diameter of the cylinders.