Magnetically separable TiO2/CoFe2O4/Ag nanocomposites for the photocatalytic reduction of hexavalent chromium pollutant under UV and artificial solar light

In this work, novel ternary catalysts Ag/TiO2/CoFe2O4 were synthesized with variable ferrite content for the photocatalytic reduction of Cr+6 pollutant, under UV and solar light illumination. Both TiO2 (T) and CoFe2O4 (CF) were synthesized using the sol-gel method followed by hydrothermal treatment to prepare the TiO2/CoFe2O4 (TCF) composite. Silver nanoparticles were successfully loaded on the surface of TCF to get different Ag/TCF composites. The analysis of their crystal structure indicated the presence of pure anatase phase TiO2, cubic CoFe2O4, and silver nanoparticles, in both XRD patterns and Raman spectra. It was found that the addition of silver nanoparticles to the titania/ferrite composite has a great contribution to the photocatalytic reduction of Cr+6 species. The photocatalytic reaction mechanism was studied by applying scavenging reaction process and spin trap experiments, revealing that photogenerated electrons were mainly responsible for the reduction of Cr+6 species. After the photocatalytic experiments, the composite catalyst can be easily separated from the reaction solution with a magnetic bar and be re-used.