Influence of pH and time on the stability of aqueous alumina suspensions containing sodium polyacrylates: A revisited process

The action of polyacrilates as stabilizing agents in alumina aqueous suspensions has been investigated using viscometry, zeta potential, and photon correlation spectroscopy (PCS) measurements. The present work emphasizes that the study of stability of dispersions using polyelectrolytes must necessarily include several techniques in order to evaluate different physicochemical properties of colloidal suspensions, and thus attain a wide comprehension of the system under analysis. In our point of view, this is necessary because, for instance, while viscosity measurements suggest that there is no advantage in the use of the polyelectrolyte at some pH values, particle size measurement as a function of time shows that the presence of PANa at that pH values allows a longer handling time in suspension processing. Low molecular sodium polyacrylate presented a good performance as a deflocculating agent, because it leads to dispersions of low viscosity, stable at a wide range of pH, and also low variation in particle size as a function of time.