How long can the iron nails last before the arsenic adsorption capacity is finished?
The nails’ arsenic adsorption capacity is dependent on the amount of iron nail surface area available. We have a number of filters installed in 2002 and the capacity of the iron nails to remove arsenic is not yet exhausted. We hypothesize that as the iron nails get rusted, the rusted iron particles become exfoliated and fall to the fine sand layer. This exfoliation exposes new iron surface, allowing more arsenic to be adsorbed. Annual washing of the iron nails can help to expose additional iron surface for improved adsorption capacity.
