Preparation of CaF2/TiO2/Ln2Ti2O7 (Ln = Er, Tm, Yb) based magnetite near-infrared photocatalyst supported on waste ferrite

Fabrication of magnetite near-infrared (NIR) photocatalyst using the waste ferrite mixed-ferrite (M-Fe3O4) derived from electroplating wastewater as the magnetic agent is a promising way to reduce environmental pressures. Here, the SiO2 coated M-Fe3O4 (M-Fe3O4@SiO2) is added to fabricate the magnetite NIR photocatalyst of Er3+/Tm3+/Yb3+-M-Fe3O4@SiO2/CaF2/TiO2/Ln(2)Ti(2)O(2) (Ln=Er, Tm, or Yb) (ETY-FCTL). The spherical shaped ETY-FCTL contains the phases of anatase-TiO2, (Ca0.8Yb0.2)F-2.2, Ln(2)Ti(2)O(7), and the residual CaTiO3, and exhibits strong short-wavelength light absorption property. According to the broadband light absorption ability, most of the upconverted light (blue, green, UV light) can be used by ETY-FCTL for photocatalysis. Under the UV-vis-NIR irradiation, ETY-FCTL has higher removal rate of methyl orange (99.0%) compared to M-Fe3O4@SiO2/CaTiO3 (50.2%), Er3+/Tm3+/Yb3+-M-Fe3O4@SiO2/CaTiO3/TiO2 (68.0%), and Er3+/Tm3+/Yb3+-M-Fe3O4@SiO2/CaF2/Ln(2)Ti(2)O(2) (20.8%). ETY-FCTL also possesses the highest removal efficiency of salicylic acid among the samples. The best photocatalytic activities of ETY-FCTL are resulted from its high light absorption property and efficient electron-hole pair separation. (C) 2016 Elsevier Ltd, All rights reserved.