Electrophoretic Studies of Coagulation for Removal of Organic Color: Fid-Bau Portal

Electrophoretic Studies of Coagulation for Removal of Organic Color

Black, A. P. / Willems, Donald G.

This study discusses how microelectrophoresis is proving to be a valuable tool in measuring the mobility of, and to calculate, where necessary, the zeta potential of a floc particle at any stage of the coagulation process. Thus, a better understanding has been gained of the complex mechanisms that are involved in coagulation. These studies have confirmed numerous observations of other workers which were not supported by this type of experimental data; at the same time, the studies have shown certain other assumptions to be untenable. For example, Miller's belief, widely accepted for many years, that the trivalence of the aluminum and ferric ions is the predominant factor in coagulation has not been confirmed by the authors' studies. On the contrary, Mattson's assumption that the hydrolysis products of the two ions are most effective in reducing or reversing the zeta potential of floc particles has been confirmed. The behavior of the four clays that have been studied to date confirms Langelier's assumption that base exchange is an important factor in the coagulation of clays, and his concept of the importance of “binder alum” in bringing about orthokinetic coagulation is consistent with all of the authors' data. Further work with other clays and other colored waters is needed and will be forthcoming. In addition the role played by natural and synthetic polyelectrolytes as aids to coagulation needs further elucidation. But none of the authors' studies to date has served to minimize the importance of the jar test as the most valuable tool for the practical control of the coagulation process.