The total potential energy of interaction between colloidal particles and solid surfaces, which is the sum of the attraction potential energy and that of repulsion, depends on particle size, the Hamaker constant, the surface potential, and the Debye᎐Huckel reciprocal distance, which is immediately related to the ¨Ž . ionic strength of carrier solution. With the aid of the field-flow fractionation FFF technique the adhesion and detachment of colloidal materials on and from solid surfaces were studied. The ideal experimental conditions for the adhesion of Ž . Ž . w Ž . x haematite ␣-Fe O , titanium dioxide TiO , and hydroxyapatite Ca PO OH 2 3 2 5 4 3
submicrometer colloidal particles on the Hastelloy C channel wall, as well as for the adhesion of the sulfides Cu Zn S and Cu Zn S supramicrometer parti-0.1 0.9 0.2 0.8 cles on the glass channel wall, were those decreasing the surface potential of the particles through the pH and ionic strength variation as well as increasing the effective Hamaker constant between the particles and the wall through the surface tension variation. On the other hand, the ideal experimental conditions for the detachment of the same colloids from the solid surfaces were those decreasing the potential energy of attraction and increasing the repulsion potential energy. ᮊ 1997