Abstract
In this study, we investigated on how the salt concentration influenced the mechanism of flocculation for Na-montmorillonite-water system based on rheological method under extremely diluted and alkaline state suspension.
Oue conclusions are as follows:
1) The montmorillonite-water system showed stable dispersion without dependence on the salt concentration when the salt concentration was less than 1.2 ×10-2 mol/l.
2) When the salt concentration exceeded 1.2 ×10-2 mol/l, dispersed particles started to flocculate under stable conditions and gelation occured; the gel structure developed further by increasing salt concentration from 1.2×10-2 mol/l to3.0×10-1 mol/l.
3) On the other hand, floc was formed by the bonding of dispersed particles in the flow state when the salt concentration exceeded 1.2 ×10-2 mol/l. The effective volume of floc increased as the salt concentration increased within the range of 1.20times;102-5.6×10-2 mol/l/.
4) However, for salt concentration between 5.6 ×10-2 mol/l and 1.8 ×10-1 mol/l, the effective volume of floc decreased with increasing salt concentration. This fact can be explained using the flocculation model proposed by Keren et al, starting that montmorillonite platelet is the flexible structure
