CENTRIFUGAL SPLITT FRACTIONATION - NEW TECHNIQUE FOR SEPARATION OF COLLOIDAL PARTICLES

A centrifugal SPLITT fractionation system has been assembled for the p urpose of extending the capabilities of gravitational SPLITT fractiona tion to materials in the colloidal size range and to particles of low density. The integrity and capabilities of the system are examined usi ng polystyrene and other latex beads. Fractionation is illustrated usi ng a mixture of latex beads of two different diameters, 0.60 and 1.05 mum. In addition, palladium particles in the size range 0.03-0.3 mum a re separated into small and large particle size fractions with diamete rs below and above 0.15 mum, respectively. Continuous fractionation is then carried out for periods ranging from 7 h to 3 days using a polyd isperse poly(vinyl chloride) latex material (0.2-2 mum, cut at 1.1 and 0.7 mum) and a polydisperse nematic curvilinear align phase liquid cr ystal emulsion (1-10 mum, cut at 2.8 mum). Fractionation is verified b y electron microscopy and by size analysis using sedimentation field-f low fractionation. Throughputs are the order of 0.5-1.0 g/h; guideline s are provided to expand this level significantly.