Study on Analysis and Sedimentation of Alumina Nanoparticles

Dispersion and aggregation behavior of nanoparticles in aquatic environment may be affected by pH, salinity, and dissolved organic matter, which would change its ecological risk. Effects of time, power and temperature on the alumina nanoparticles (nano-Al(2)O(3)) ultrasonic dispersion in water were discussed. Al(2)O(3) had a best ultrasonic dispersion for 30 min at 105 W and 30 °C. The concentration of Al(2)O(3) could be measured by ultraviolet (UV) spectrophotometer, and the method was efficient and accurate. Furthermore, the sedimentation rate of Al(2)O(3) was related to pH, salinity, and its concentration in the artificial seawater. When pH was 7.31, approaching the isoelectric point of Al(2)O(3), they aggregated and settled fastest. Settlement coefficient (k) of Al(2)O(3) increased by 3 and 2.7 times while the salinity and its concentration increased. The sedimentation rate was higher in natural seawater than that in artificial seawater. All results indicated that nano-Al(2)O(3) would be removed in aquatic environment.