In situ measurement of charge on polystyrene particles in colloidal suspension

Abstract

Raman scattering is used to estimate, in situ, the charge on polystyrene particles in aqueous suspension. The intensities of the Raman modes at 1001 and 1032 cm-1 arising from dissociated and undissociated -SO4K end groups in the particle are used to estimate the degree of dissociation. This technique enables one to estimate the charge with an accuracy of 5%. The charge on the particles in suspensions having different impurity concentration, temperature, dielectric constant and effective density can be determined in situ. The measured charge is found to decrease and then increase as a function of impurity concentration.