(639c) Magnetic EDTA: Coupling Heavy Metal Chelators to Metal Nanomagnets for Rapid Removal of Cadmium, Lead and Copper From Contaminated Water

Nanomagnets combine high specific surface area (small particles) and ease of separation (directed movement of the particles in liquids). Until recently, the use of iron oxide particles had opened fascinating applications of magnetic separation, (Sun, Ding et al. 2006) but limited stability prohibited the use of iron oxide based nanomagnets in combination with complexing agents in acidic media which would immediately dissolve the particles. Carbon-encapsulated metal nanomagnets most recently opened access to chemically stable magnets (Grass and Stark 2006; Grass, Athanassiou et al. 2007) with strongly improved bulk magnetization (stronger magnetic forces result in faster removal). The carbon layers further provide an anchoring point for functional groups on the particles surface, accessible by diazonium chemistry (Tan and Grass 2008). Attachment of EDTA-like chelators to carbon coated metal nanomagnets results in a magnetic reagent for the rapid removal of heavy metals especially lead, cadmium and copper from solutions or contaminated waste water streams by three orders of magnitude to concentrations as low as µg/L. Figure 1. Magnetic separation test in 10 l water with 1 g carbon-coated cobalt particles. Left figure, start of magnetic separation as a permanent magnet was placed in the lower left corner. Middle figure was taken after 1 minute. After 2 minutes the stirrer was stopped and the right figure shows the end of the separation. More than 97% of the particles were removed. Grass, R. N., E. A. Athanassiou, et al. (2007). "Covalently Functionalized Cobalt Nanoparticles as a Platform for Magnetic Separations in Organic Synthesis." Angewandte Chemie Int. Ed. 46(26): 4909-4912. Grass, R. N. and W. J. Stark (2006). "Gas phase synthesis of fcc-cobalt nanoparticles." Journal of Materials Chemistry 16(19): 1825-1830. Sun, Y. B., X. B. Ding, et al. (2006). "Magnetic separation of polymer hybrid iron oxide nanoparticles triggered by temperature." Chemical Communications(26): 2765-2767. Tan, C. G. and R. N. Grass (2008). "Suzuki cross-coupling reactions on the surface of carbon-coated cobalt: expanding the applicability of core-shell nano-magnets." Chemical Communications(36): 4297-4299.