Magnetic Separation of Metal Ions

The magnetic separation was investigated for Co2+ (9500 × 10-6 cm3 mol-1) and Fe3+ (14600 × 10-6 cm3 mol-1) ions and for Cr3+ (6200 × 10-6 cm3 mol-1) and Al3+ (−2 × 10-6 cm3 mol-1) ions. The metal ion solutions were spotted on a silica gel support, and exposed to a magnetic field of 410 kOe2 cm-1 intensity × gradient. The Co2+ ions move farther toward the maximum field than the Fe3+ ions. The result is explained by the fact that the Fe3+ ions are adsorbed more strongly on the silica gel surface than the Co2+ ions. The Cr3+ ions move farther toward the field center than the Al3+ ions. This occurs because the Cr3+ ions are attracted more strongly by the magnetic force than the Al3+ ions. It is demonstrated that the separation makes effective use of the adsorption activities as well as the magnetic susceptibilities.