Abstract
M.Sc. (Chemistry)
The preparatIon of fine powders having large surface are as was carried out
using the Hot Kerosene Drying Method (H.K.D.). In this method an emulsion
containing An aqueous solution of a sought after cation is emulsified
along with kerosene having a high boiling point (200+ C). The emulsion
is then added to a given amount of the kerosene at a predetermined temperature
above the boiling point of water, in a drop-wise fusion, during
which the water con concerned in the emulsion rapidly evaporates resulting
in the solid accumulating on the bottom of the flask. The powder is then
separable from the kerosene using conventional means.
Tungsten and iron-containing powders were each, made according to this
method. The preliminary preparations were carried out with tungsten containing
emulsions.
In an attempt to produce an emulsion having the smallest internal phase
diameter, w/o iron-containing emulsions prepared using different concentrations
of the emulsifying agents and various kerosene-water ratios, were
photographed microscopically under high magnification. Sedimentation rates
and the presence of phase separation of the emulsions were recorded.
In this manner an optimum emulsion with regard to particle size and stability
was found.
This emulsion composition was employed to prepare a series of emulsions with
varying concentratiOns of the iron sulphate solution. Powders were prepared
from these emulsions by subjecting them to the ".K.D. procedure. In another
series of experiments the effect of the kerosene bath temperature on the
quality of the poWders was studied. The surface areas of the solids were
determined by using a dynamic method, and these could be directly related
to the particle size of the powders for purposes of comparison...