Copper and cadmium removal by Mn oxide-coated granular activated carbon

Mn oxide-coated granular activated carbon (MnTOG) was prepared by coating Mn oxide onto granular activated carbon (TOG). The Cu(II) and Cd(II) adsorption capacities of granular activated carbon were significantly improved by Mn oxide coating. Mn oxide, TOG and MnTOG had pH(zpc) about 6, 8.5, and 5.8, respectively. From multiple Cu(II) adsorption/regeneration cycle tests, MnTOG can be regenerated and reused through at least six cycles. More than 70% of the adsorbed Cu(II) was recovered at the end of six adsorption cycles. MnTOG has the ability to remove Cu(II) and Cd(II) to trace levels (<4 mu g/L) in a column process. For Cd(II) and Cu(II) sorption by MnTOG, Cu(II) had a higher adsorption capacity and a slower diffusion process. There was competition between metals: Cd(II) removal was hindered by the presence of Cu(II), however, Cu(II) removal was only slightly inhibited in the presence of Cd(II). (C) 2005 Elsevier B.V. All rights reserved.