Effect of Solution Environment on Dead-End Microfiltration Characteristics of Rutile Suspensions

Microfiltration experiments were conducted under a constant pressure of 196 kPa, using a dead-end filter. The filtration properties were studied using titanium dioxide suspensions of the rutile form to determine the effects of such solvent environments as pH and the added salt. Both the average porosity and the average specific filtration resistance of the filter cake were determined. It was highlighted through this study that the electrical nature of particles depending on the solution environment plays a significant role in determining the structure of the filter cake which, in turn, influenced the filtration rate in microfiltration of dispersions of metal oxides. It was demonstrated unequivocally that the average porosity in the filter cake had a maximum and the average specific filtration resistance was minimal around the isoelectric pH. These results were in contrast to those observed with ultrafiltration of protein solutions. Such charge effects of particles were weakened in the presence of salts.