THE EFFECT OF CARRIER SOLUTION ON THE PARTICLE-SIZE DISTRIBUTION OF INORGANIC COLLOIDS MEASURED BY STERIC FIELD-FLOW FRACTIONATION

The number average and the weight average particle diameters for suspended inorganic colloids found by the new technique of steric field-flow fractionation may be successfully used provided that the most suitable carrier solution is selected, in order to minimize the coagulation and adhesion phenomena. In the present work polydisperse, irregular colloidal particles of FePO4·2H2O (strengite) were studied. The average particle diameters were found to vary with the electrolyte concentration in the suspending medium. A strong variation of the number and weight average particle diameters was also observed with the quantity of the surfactant added to aquatic medium in order to increase colloidal stability. The influence of the electrokinetic charge of the FePO4·2H2O particles in relation to the surface charge of the material of the column employed, on the particle size measured was investigated. The proper carrier solution for minimizing coagulation and adhesion phenomena in the FePO4·2H2O colloidal particles was found to contain either 1.5% (v/v) detergent FL-70 and 0.1 MKNO3 or 0.5% (v/v) detergent FL-70 and 0.033 MNa2SO4. © 1990 Steinkopff.