Review of Magnetic Carrier Technologies for Metal Ion Removal

Magnetic carriers are magnetic materials designed to bind selectively on some non -magnetic materials to make them separable using magnetic separation. It allows magnetic separation, a fast, efficient, high capacity and well-developed industrial technology, to be applied to the separation of materials that are otherwise non-magnetic. One application is in metal ion recovery from dilute effluents. Magnetic carrier technologies offer some advantages over other more conventional metal ion separation techniques such as ion exchange, carbon adsorption, and precipitation. Various magnetic carrier technologies have been developed using different magnetic materials (for example, micro-sized magnetite of magnetic oils) and controlling the attachment of the carrier to the target species through specific binding mechanisms (for example, electrostatic adsorption or chemical affinity). A full-scale industrial water treatment application is illustrated in the case of the Sirofloc process. The review summarizes the efforts over the last twenty years to develop carriers with high loading capacity and selectivity. General principles for the design of magnetic carriers are summarized.