The effect of sodium polyacrylate on the aggregation and sedimentation states of griseofulvine (primary particle size γ
o of 1.2μ) and calcium carbonate γ
o(of 1.8μ) were studied, in the presence of sodium dodecyl sulfate (SDS), methylcellulose, polyoxyethylenesorbitane oleate (POE-SO), sodium chloride, or polyvinylpyrrolidone (PVP), by measuring degree of apparent aggregation γ
m/γ
o, amount of adsorption (X), and ζ-potential in the suspensions, and by measuring porosity (ε) and tortuosity (q) of the sedimentation bed. Reduced viscosity (ηsp/C) of PANa increased in the presence of MC and decreased in the presence of other additives. Values of γ
m/γ
o and ε showed a maximum on their plots against the concentration of PANa, at 0.0075 g/100 ml for GR, and at 0.005 g/100 ml for CaCO
3. This tendency was not affected by the coexisting materials. These values shifted to higher values by the addition of MC at 0.05 g/100 ml, and to lower values by the addition of other materials. Values of γ
m/γ
o.ε, and X decreased, and q and ζ-potential increased with the increase of pH. For both GR and CaCO
3, these quantities gave different values when the order of addition of PANa and SDS to the CaCO
3 suspension was changed. The adsorption isotherms of PANa on GR and CaCO
3 at 25° were of Langmuir type. The ζ-potential was increased with the increase of PANa concentration. In the graph showing the relation between ε and q, all plots fell on the same line. The ratio, of q
V/
H. which indicates the anisotropy of sedimentation bed, increased with the increase of ε, where qH is the horizonta tortuosity and qv is the vertical tortuosity.
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