abstract
In this work, and for the first time, the production of waste-based magnetic geopolymer spheres by a simple heat treatment under a reductive atmosphere is reported. Upon heat treatment, the iron oxide present in bauxite wastes (red mud), used as a solid precursor, is reduced to magnetite, thus producing magnetic spheres without the need for the addition of any secondary magnetic materials. The magnetisation of these mm-size materials reached 5.34 A m2 kg-1, suggesting they contain up to 6 wt% magnetite. This was demonstrated to be sufficient for their magnetic separation/removal, without the need for the addition of any extra magnetic iron oxides to the waste material. The magnetic spheres were then evaluated as sorbent materials for the removal of lead from water, selected as a model pollutant compound. These porous bulk-type sorbents showed high metal removal efficiency reaching an uptake value of 19 mg/g at pH 5 after 24 h of contact time. These promising results, and the easy post-treatment recovery of the waste-based magnetic spheres by the use of inexpensive permanent magnets, demonstrate the potential of the proposed strategy to address environmental concerns.
keywords
POROUS FLY-ASH
subject category
Environmental Sciences & Ecology
authors
Gameiro, T; Carvalheiras, J; Gonçalves, NPF; Amaral, JS; Pullar, RC; Labrincha, JA; Novais, RM
our authors
João António de Sousa Carvalheiras
PhD Student
João António Labrincha Baptista
Full professor
João Cunha de Sequeira Amaral
Assistant Researcher
Nuno Gonçalves
Junior Researcher
Rob Pullar
Collaborator
Rui Miguel Novais
Assistant Professor
Tânia Gameiro
Junior ResearcherGroups
G1 - Porous Materials and Nanosystems
G2 - Photonic, Electronic and Magnetic Materials
G4 - Renewable Materials and Circular Economy
Projects
CICECO - Aveiro Institute of Materials (UIDB/50011/2020)
CICECO - Aveiro Institute of Materials (UIDP/50011/2020)
Associated Laboratory CICECO-Aveiro Institute of Materials (LA/P/0006/2020)
3D Printed Fouling-Resistant Photoactive Membranes for Wastewater Treatment (PURAQUA)
acknowledgements
This work was developed within the scope of the project CICECO-Aveiro Institute of Materials, UIDB/50011/2020 (DOI 10.54499/UIDB/50011/2020) , UIDP/50011/2020 (DOI 10.54499/UIDP/50011/2020) & LA/P/0006/2020 (DOI 10.54499/LA/P/0006/2020) , financed by national funds through the FCT/MCTES (PIDDAC) . The authors would like to thank FCT project MAXIMUM (PTDC-CTM-CTM-2205-2020, DOI 10.54499/PTDC/CTM-CTM/2205/2020) . NG acknowledges the funding from the European Union's Horizon Europe research and innovation programme under the Marie Sklodowska-Curie Actions PF grant agreement No 101065059.