Electrophoretic Characterization of Ciay Mineral Systems for Smectite Recovery

摘要

A novel technique that makes use of electrophoretic deposition (EPD) in upgrading the quality of Philippine clay, specifically for smectite recovery, was explored in this study. Focus was given on understanding the electrophoretic behavior of smectite and kaolinite to effectively control colloidal stability during EPD. Zeta potential measurements showed that pH has negligible effect on the electrophoretic mobility of smectite, but has an appreciable effect on the mobility of kaolinite with the isoelectric point (IEP) of kaolinite recorded around pH 5. Knowing this behavior, EPD of a 3.5wt% smectite-kaolinite slurry was carried out at pH 5 and pH 10. Separation of clay minerals was expected only at pH 5 where kaolinite is almost immobile. However, analysis of deposits using XRD showed some degree of separation (-60% smectite purity) for both pH values when EPD was performed using stainless steel electrodes at a specific applied voltage and electrode gap, for twenty minutes, without stirring. Further investigation of EPD design is needed to improve smectite recovery.