Abstract
The effect of ultrasonication on a suspension of fine hydrophobic coal particles was investigated. It is shown that ultrasonication promotes wetting and separation of the whole coal into three fractions with different electrophoretic mobilities. These fractions were found to float, to sediment and to form a stable suspension. In this study, a suspension of fine coal in deionized water was sonicated for various time intervals. It is shown in this study that ultrasonication, one of the common methods of dispersion, has considerable effect on the sample properties both because of chemical changes and because of sampling problems. Electrophoretic mobility distributions of the coal in the middle phase were measured and found to vary cyclically with sonication time. Separated coal fractions were characterized by infrared spectroscopy, which indicated variations in clay content and oxidation state. The differences in these fractions were confirmed electrophoretically. Changes in the ionic composition of the water with sonication time were also measured. The principal anions released and readsorbed were sulphate, chloride, nitrate, but nitrite was only released; cations included silicon, magnesium, sodium, calcium, aluminum and iron. Sonication can be very useful as a separation tool where modification of the ionic state of the coal surface is not a critical factor. Electrophoretic results during or immediately after sonication may represent an unsteady state and a modified charged particle surface. Sonication is therefore not to be recommended as a preparation technique for dispersion in electrokinetic measurements of coal.
Published Version
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a call