INFLUENCE OF DENSITY DIFFERENCES BETWEEN DISPERSE AND CONTINUOUS PHASES ON COAGULATION

Experimentally, a difference was found between coagulation rates of qu artz in aqueous solutions, under mu g conditions and under 1 g: at mu g conditions, coagulation is faster than at 1g. This difference is con trary to theoretical expectations; however, at 1 g in dispersions in w hich there is no density difference between the disperse and continuou s phases, coagulation rate is also higher than in dispersions in which there is such a density difference. Theoretically, a difference in co agulation rates is not expected from low Reynolds number hydrodynamics . Apparently the non-linear terms in the Navier-Stokes equation become important even for small (1-3 mu m) particles, when they are close en ough for the London-van der Waals forces to be important.