Characterising the sedimentation of bidisperse colloidal silica using analytical centrifugation

This study investigates the settling behaviour of bidisperse colloidal silica suspensions in two different size ratios (100:500 nm and 500:800 nm) with various mixture volume fractions, using an analytical photocentrifuge. For dilute systems, translation rate profiles to distributions resulted more accurate measurements for both monodisperse systems than dynamic light scattering, comparison SEM. However, a critical limitation was also observed, as distinction between upper (smaller particle) lower (larger interfaces could only be measured total fractions <∼0.02. mixtures, results were compared Richardson-Zaki modified Batchelor model predictions. The proved at predicting interface rate, while models over predicted interface, likely due increased drag that most evident higher smaller particles. 100:500 cases, centrifugal rotation speeds required settle 100 particles, influence Brownian motion evident. It found particles obtained initial its terminal velocity, induced anisotropic effects or backflow from 500 fraction, which again greater proportion