Iron(III) oxide (CAS 1309-37-1): storage and disposal

The fine powder stains. A tub with a loose lid leaves a red-brown film on the shelf, on neighbouring jars and on hands, and that dust is easy to confuse with other coloured powders. Keep the powder in a closed, labelled container on a general shelf in a dry store, dated on arrival and away from food grade supplies. Where it has been issued for demonstrations that involve other powders, take the tub back and keep it apart from any metal powders or other reagents. A label that gives only 'iron oxide' is not enough, because there is more than one iron oxide.

Rust-coloured powder is what iron(III) oxide already is, so there is no sign of rusting to look for. The solid changes very little with age, which makes the container and its contents the things to check. Look for clumping from damp, red-brown dust around the lid, a faded label and an unknown date of receipt. The finding that matters is mixed content: a tub holding a grey, dark or streaked powder after a demonstration is no longer iron oxide alone. Set it aside, do not open it to sort it out and describe it as a mixture to the collection team.

We arrange this by specialist collection. We do not publish a drain or general waste route for any chemical. It is normally packed in a non-regulated or low hazard laboratory pack with compatible chemicals.

Mixtures are the awkward case. A tub that held clean iron(III) oxide and has since had something else added is now an unknown blend, and the collection team needs to be told what you know of it. Clean stock and any used or mixed tubs should be kept in separate, closed containers. The usual entry for clean powder is 16 05 09, which is not a hazardous waste entry, and the producer classifies the waste, but it is still chemical waste and must be described accurately. It must not go into a sink, a drain, general waste or a skip, and nobody should try to treat it first.

Usually held as: powder.

Tell us the container size and how many you hold. An estimate is enough to start with, and some items cannot be priced until someone has looked at them.