Novel red mud waste-derived magnetic geopolymer spheres, made without the addition of any extra iron compounds, for the removal of wastewater contaminants

• DOI: 10.1016/j.jenvman.2025.124615
• Publication Date: 2025-02-22T23:16:44Z
• Authors: Tânia Gameiro; João Carvalheiras; Nuno P.F. Gonçalves; João S. Amaral; Robert C. Pullar; João A. Labrincha; Rui M. Novais

In this work, and for the first time, production of waste-based magnetic geopolymer spheres by a simple heat treatment under reductive atmosphere is reported. Upon treatment, iron oxide present in bauxite wastes (red mud), used as solid precursor, reduced to magnetite, thus producing without need addition any secondary materials. The magnetisation these mm-size materials reached 5.34 A m2 kg-1, suggesting they contain up 6 wt% magnetite. This was demonstrated be sufficient their separation/removal, extra oxides waste material. were then evaluated sorbent removal lead from water, selected model pollutant compound. These porous bulk-type sorbents showed high metal efficiency reaching an uptake value 19 mg/g at pH 5 after 24 h contact time. promising results, easy post-treatment recovery use inexpensive permanent magnets, demonstrate potential proposed strategy address environmental concerns.