Size fractionation in a phase-separated colloidal fluid.
Phase separation of a polydisperse colloidal dispersion implies size fractionation. An application of this effect is given by size-selective purification procedures associated with the colloidal synthesis of so-called monodisperse nanoparticles. We used electron microscopy to determine detailed particle size distributions of coexisting colloidal fluid phases containing highly polydisperse iron oxide nanoparticles with a log-normal distribution (sigma = 0.54 for the total system). Analysis of N approximately 10000 particles per phase yields the first five statistical moments of the distributions. Within experimental error, the interdependence of the statistical moments is in quantitative agreement with the "universal law of fractionation" proposed by Evans, Fairhurst, and Poon [Phys. Rev. Lett. 1998, 81, 1326], even though the theory was derived in the limit of slight polydispersity.
Erné
Ben H
BH
Van't Hoff Laboratory for Physical and Colloid Chemistry and the Department of Inorganic Chemistry and Catalysis, Debye Institute, Utrecht University, 3584 CH Utrecht, The Netherlands. b.erne@chem.uu.nl
van den Pol
Esther
E
Vroege
Gert Jan
GJ
Visser
Tom
T
Wensink
Henricus H
HH