DESESTABILIZAÇÃO DE UMA SUSPENSÃO COLOIDAL DE DIÓXIDO DE TITÂNIO.

The sedimentation rate can be increased by the processes of aggregation (coagulation, agglomeration, or flocculation). The direct flocculation of colloidal particles is not sufficient for the destabilization of a colloidal suspension. Due to the very small size of the colloids, the flocs can remain with very slow sedimentation rate. Therefore, a previous step of aggregation is necessary for an efficient flocculation. In this study it was compared the influence of pre-aggregation, with a surfactant - dodecylamine (DDA) and a multivalent salt - hexahydrated aluminum chloride (HAC) in the flocculation of colloidal particles of titanium dioxide with a hydrolyzed polyacrylamide (PAMH). The results were evaluated in terms of turbidity of the supernatant and final compaction of the sediment. The pre-aggregation significantly improves the flocculation with PAMH. The pre-treatment with DDA produces largest flocs, low turbidity overflow, and more compacted sediment, compared to the pre-treatment with HAC. [ABSTRACT FROM AUTHOR]