Treatment of alumina and silica CMP waste by electrodecantation and electrocoagulation

摘要

The aim of this study was to explore the feasibility of separating solids from dilute suspensions typically encountered as a waste in chemical mechanical polishing (CMP) operations, through the application of an electric field. Specifically, two methods, electrocoagulation and electrodecantation, were studied for the concentration of dilute silica and alumina suspensions. The effect of agitation, applied field strength, and switching of the polarity of the electric field on the solid/liquid separation process has been investigated. Experimental results show that electrocoagulation can be used to efficiently remove particles from suspension by forming aggregates. This is in contrast to the electrodecantation process, which requires more time but removes the solids without modifying the mean particle size.