Effect of floc structure on the rate of Brownian coagulation

A modified expression for the Smoluchowski solution for the temporal evolution of the number concentration of flocs subject to Brownian coagulation is proposed, taking into account the effect of the growth of floc structure. In the proposed equation, the effect is expressed as a decrease of free volume in the liquid phase due to the increase of effective floc volume in accordance with the progress of coagulation. The validity of the proposed equation was tested by coagulation experiments using polystyrene latex particles. Direct counting of the number of flocs under microscopy provided accurate data on the temporal evolution of the number concentration of flocs. The obtained rate gradually increases in accordance with the growth of floc structure. This behavior agreed exactly with the prediction based on the proposed equation.

A modified expression for the Smoluchowski solution for the temporal evolution of the number concentration of flocs subject to Brownian coagulation is proposed, taking into account the effect of the decrease of free volume in the liquid phase due to the increase of effective floc volume in accordance with the progress of coagulation.Figure optionsDownload as PowerPoint slide