Carbonised red mud – A new water treatment product made from a waste material

Proposals to use red mud, the waste produced by the extraction of alumina from bauxite ore in the Bayer process, as a material for treatment of heavy metal-contaminated water are limited by its inherent alkalinity and variability. Attempts to lower its pH have been largely unreliable. However, an alternative strategy is carbonisation of red mud by catalytic hydrocarbon cracking, which results in a magnetic material of greater surface area. The efficacy of this material has been compared with that of the untreated parent red mud and acidified red mud for the sorption of CrO42−, Cu2+ and Pb2+. Carbonised red mud does not remove CrO42− from solution, but shows enhancement of Cu2+ and Pb2+ removal. There is an approximate ten-fold increase in removal of Cu2+ and Pb2+ by carbonised red mud compared with acidified red mud.

Graphical abstractFigure optionsDownload full-size imageDownload as PowerPoint slideHighlights► Carbonised red mud is a novel material. ► It is produced when red mud is used as a catalyst for methane cracking. ► It has potential as a treatment to remove heavy metals from contaminated water. ► It is magnetic, allowing easy separation of metal-loaded material.