Rahner, S., Dept. of Environmental Sciences & Energy Research, The Weizmann Institute of Science, 76100 Rehovot, Israel.
Magaritz, M., Dept. of Environmental Sciences & Energy Research, The Weizmann Institute of Science, 76100 Rehovot, Israel.
Amiel, A.J., Dept. of Environmental Sciences & Energy Research, The Weizmann Institute of Science, 76100 Rehovot, Israel.

Sand grains coated with Fe-hydroxide were compared to uncoated sand grains as an absorbant filtration media for the treatment of metal-bearing waters. Coated and uncoated sand grains were placed into dialysis cells of a multilayer sampler and then placed into a research well. After two months of exposure, the samples were retrieved and analyzed for Cr, Pb, Ni, Cd, Mn and Co concentrations. Transmitted light and scanning electron light microscopy showed that the coating prevailed in the field and was not removed. Only Cr showed significant enrichment on the coated material compared to the uncoated material, indicating that the exposure of the Fe-coated surface to groundwater was sufficient for preferential scavenging of Cr from the water. The eight-fold enrichment of Cr may be related to its oxidation state of +3, thereby readily permitting substitution into the Fe3+ position in the coating material. The rest of the studied metals were only slightly enriched in the coated grain. -Authors