Scavenging effects of Fe-hydroxide-coated sand in phreatic aquifers

The feasibility of using sand grains coated with an amorphous iron oxide known as ferrihydrite to scavenge metals from polluted groundwater was investigated. Coated and uncoated grains were placed in dialysis cells of a multilayer sampler which was installed in a research well. The samples were retrieved and analysed for chromium, lead, nickel, cadmium, manganese and cobalt concentrations after 2 months of exposure. Only chromium showed substantial enrichment on the coated grains, suggesting that preferential scavenging of chromium from groundwater was feasible. Chromium was enriched 8-fold on the treated grains, while the other metals were only slightly enriched.