The effect of composition of water-ethanol solutions on the kinetics of coagulation of fused quartz suspensions

The effect of composition of water-ethanol solutions containing 0-96 vol % alcohol on the coagulation kinetics of dilute fused quartz suspensions is studied using flow ultramicroscopy technique. It is established that, in both water and ethanol containing 4 vol % water, freshly prepared quartz suspensions are stable with respect to aggregation; at ethanol concentrations from 10 to 90 vol %, an ultrafast coagulation takes place, with characteristic time (coagulation period) being essentially smaller compared to a value corresponding to the Smoluchowski theory of fast coagulation kinetics. It was shown that the aging of the aforementioned suspensions for more than 24 h results in slow coagulation at high and low alcohol content, but its ultrafast character is retained in the ethanol concentrations range of 40-48 vol %. The probable reasons for the ultrafast coagulation in the disperse systems specified are discussed.