(227e) Magnetic Edta – Attaching Metal Chelators to Nanomagnets for Water Purification and Heavy Metal Recovery

Magnetic particles are routinely applied in biochemistry separations. Unfortunately their application is often limited due to high costs, poor stability and low binding capacities. Recently we prepared graphene-like coated metallic nanoparticles by reducing flame spray synthesis [1,2]. The coating on the one hand protects the metal nanoparticles from oxidation below 190°C and dissolution in concentrated acids. On the other hand it allows the introduction of covalently bound functional groups via diazonium chemistry [3] or physical adsorption, offering the freedom of organic chemistry on the particle surface.

The functionalized magnetic particles represent a promising modular platform for removing a wide range of contaminants. Attaching EDTA-like chelating agents to the surface allows the removal of heavy metal ions from aqueous solutions. Furthermore, attaching a thiourea-like chelating agent allows the efficient removal of precious metal ions in highly acidic solutions. The low costs and particle stability favor this preparation method and material for large-scale separation application of metal ions in ultra low concentrations.

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.

[1] R. N. Grass, W. J. Stark, J. Mater. Chem. 2006, 16, 1825.

[2] R. N. Grass, M. Dietiker, R. Spolenak, W. J. Stark, Nanotechnology 2007, 18, 035703.

[3] R. N. Grass, E. K. Athanassiou, W. J. Stark, Angewandte Chemie 2007, 26, 4909