Factors Affecting Zeta Potential of Iron Oxides

This review examines the factors that affect the isoelectric point (IEP) and the magnitude of the Zeta potential for hematite. It addresses the various values that have been reported in the literature, with natural hematite typically having a more acidic IEP than does high-purity synthetic hematite. The key finding is that the IEP for natural hematite is very similar to that for silica. This is consistent with a coating of silica slimes forming on natural hematite, causing the hematite surfaces to behave as if they were silica surfaces. Adsorption of chemical reagents on the hematite surfaces causes changes in the magnitude of the Zeta potential, generally without changing the IEP.