Recycling of solid wastes in the synthesis of Co-bearing calcium hexaluminate pigment


Cobalt doped calcium hexaluminate was firstly synthesized using pure reagents; subsequently, the pure reagents were substituted with industrial wastes, the composition of which had been characterized using X-Ray diffraction and X-Ray fluorescence namely, Al-anodising sludge replaced pure aluminium whilst marble cutting rejects and foundry sand were employed as sources of calcite and silica, respectively. As expected, cobalt doped hibonite was the major phase present in calcined powders and displayed an intense blue coloration due to the incorporation of cobalt in tetrahedral positions, as confirmed by transitions from (4)A(2)(F) to the excited (4)T(1)(F) and (4)T(1)(P) states observed from UV-Vis-NIR absorption spectra. The novel waste-derived hibonite pigment showed strong and stable colouring potential when applied in different ceramic supports. (C) 2009 Elsevier Ltd. All rights reserved.



subject category

Chemistry; Engineering; Materials Science


Hajjaji, W; Seabra, MP; Labrincha, JA

our authors


The work was supported by FCT (project PTDC/CTM/72318/2006). The support of Revigres in the industrial trials should also be emphasised.

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