Photocatalytic activity of CaTiO3 derived from roasting process of bauxite residue

Utilization of bauxite residue is an urgent issue confronting the worldwide alumina industry. A CaTiO3-rich material has been successfully collected from bauxite residues based on our previous work, and the possibility of applying this obtained CaTiO3 as photocatalyst for degradation of rhodamine B was evaluated in this study. X-ray diffraction, Fourier transform infrared spectroscopy, field-emission scanning electron microscopy, X-ray photoelectron spectroscopy, UV-vis spectroscopy, photoluminescence microscopy, and Brauner-Emmet-Teller surface area analyzer were employed to characterize the CaTiO3 samples. Interactive effects of dominant factors on degradation of rhodamine B were examined through surface response methodology and optimal conditions were obtained. H3PO4 acidification was effective to enhance the photocatalytic activity of CaTiO3. More than 10 h was required for RhB degradation in presence of CaTiO3 while only 3 h was needed to achieve 85% removal of RhB using the acidified CaTiO3. CaTiO3 has larger band gap and lower separation efficiency of photoelectrons-hole pairs than TiO2, but H3PO4 acidification significantly reduced the recombination of photoelectrons-hole pairs and thus made more photoelectrons/holes participate in reactions. This study has validated a promising routine towards fully comprehensive utilization of bauxite residues, and simultaneously addressed a novel idea for using solid-waste to treat wastewater, thereof was very favorable to the sustainable development of environment. (C) 2019 Elsevier Ltd. All rights reserved.