Figure 4

Average hydrodynamic diameters ( dH ) of montmorillonite-only suspensions (8 mg/L) in constantly stirred solutions were measured as a function of time after mixing with artificial seawater (ASW) using dynamic light spectroscopy. The pH was circumneutral. The results show a lack of aggregation in the zero salinity suspension. On the other hand, at elevated salinity values, (S = 1.8 – 7.2 psu), the colloidal particles rapidly aggregate during the initial ~15 minutes following the ASW mixing. In the S = 1.8 psu suspension, the aggregates reach the steady state average size of dH ≈ 600 nm after 20 minutes. In the S = 3.6 and S = 7.2 psu suspensions, the aggregates become larger (dH ≈ 1,100 nm) after the initial rapid aggregation.