Dynamic mobility spectra of multicomponent colloidal suspensions

Recently, the electrokinetic sonic amplitude (ESA) signal has been measured over a range of frequencies (collectively termed the dynamic mobility spectrum) for the simultaneous determination of particle charge and size in moderately concentrated suspensions. Based on these advances, we develop theory describing the dynamic mobility spectra for multicomponent suspensions, The dynamic mobility spectrum of multicomponent suspensions can be interpreted as the weighted sum of the individual component dynamic mobility spectra. Weighting coefficients are defined and a methodology for determining these weighting coefficients for binary suspensions with a least-squares technique is developed, Results from multicomponent suspension data are in good agreement with theory. Experimental conditions are restricted to constant pH and ionic strength to avoid changes in the shape of the dynamic mobility spectra of the components, possibly due to agglomeration effects.