Question: what metal has proved to be one of the best at cleaning poisoned water

Harriet Aitken answered on 19 Jun 2014:

Hi Rachelp,

It’s one of the best for a few reasons, but you really have to think about what best means – usually when you think of best you think of something being the most efficient at removing certain chemicals from water but unfortunately ‘best’ can also mean the most expensive which some people aren’t able to afford.

So when I said best, I should really have explained a bit more! The main metal I use is iron, which is one of the most common metals on earth making it cheap, unlike gold or platinum. A lot of iron is also thrown away because it is rusty which is perfect for my system because I need rust to remove toxic species (at the moment I am focusing on arsenic).

Rust is actually very reactive and can quickly form strong bonds with arsenic through adsorption. Over a wide range of water conditions these bonds remain intact – for example if you add acid to rust containing arsenic it will not easily part with the rust meaning that it is stable, and unlikely to make its way back into drinking water.

So iron is one of the best materials for removing certain chemicals from drinking water because it is very effective, pretty reliable and cheap.

Hattie