POTENTIAL-BARRIER FIELD-FLOW FRACTIONATION, A VERSATILE NEW SEPARATION METHOD

A new method called potential-barrier field-flow fractionation, which is a combination ' of potential-barrier chromatography and sedimentation field-flow fractionation (SdFFF), is presented for the separation and characterization of colloidal materials. The separation is based either on particle size differences or on Hamaker constant, surface potential and Debye-Hückel reciprocal distance differences. In its simplest form the technique consists in changing the ionic strength of the carrier solution from a high value, where only one of the colloidal materials of the binary mixture subjected to separation is totally adsorbed at the beginning of the SdFFF channel wall, to a lower value, where the total number of adhered particles is released. The method was applied to the separation of haematite and titanium dioxide spherical colloidal particles and to the separation of haematite spherical particles different sizes. At the same time as separation was occuring, the particle sizes of the colloidal materials of the mixture were determined. The experimental values of particle diameters were in good agreement with those obtained by transmission electron microscopy or determined by normal SdFFF. Finaly, the retention perturbations due to particle (α-Fe2O3 and TiO2)-wall interactions in SdFFF were investigated. © 1990.