Facile synthesis of highly efficient and cost-effective photo-Fenton catalyst by ball milling commercial TiO2 and natural magnetite

Abstract Heterogeneous Fenton reaction is a usable technique to remove organic contaminants in water, while developing highly efficient and cost-effective catalysts with simple preparation method is critical for its practical application. In this work, novel TiO2/Mag composites were prepared from commercial TiO2 and natural magnetite (Mag) via a facile ball milling process. We expect the obtained composites to be efficient photo-Fenton catalysts, as photo-generated electrons from TiO2 can be transferred to Mag to accelerate the reduction of Fe(III) to Fe(II), promoting the decomposition of H2O2 and production of ·OH. Structural characterization results exhibited ball milling could not change mineral phases of both TiO2 and Mag. TiO2/Mag composites remained good magnetic saturation and could be rapidly separated from reaction medium. In degrading cefotaxime, TiO2/Mag composites showed high photo-Fenton catalytic activities, with the degradation rate by 10%TiO2/Mag at near neutral pH of 5.6 being about 11.6 and 8.2 times higher than that of natural and ball-milled Mag, respectively. Moreover, even at low H2O2 concentration of 1 mmol/L, 10%TiO2/Mag remained relatively high photo-Fenton catalytic activity when compared to natural and ball-milled Mag. The better production of ·OH in the photo-Fenton system catalyzed by 10%TiO2/Mag (0.244 mmol/L) than that by natural and ball-milled Mag (0.049 and 0.064 mmol/L) also illustrated efficient utilization of H2O2 by 10%TiO2/Mag. Above results well support our hypothesis that photo-generated electrons from TiO2 were transferred to Mag, which then benefited the Fenton reactivity of Mag and degradation of cefotaxime. In all, TiO2/Mag composites prepared by ball milling have promising practical application in water treatment, thanks to their merits such as high photo-Fenton catalytic activity, facile preparation, cost-effective, easy magnetic separation, good stability, suitable for near neutral pH, and efficient utilization of H2O2.