Removal of Cr(VI) from acid wastewater by BC/ZnFe2O4 magnetic nanocomposite via the synergy of absorption‐photocatalysis

Photocatalysis is a promising solar energy conversion technology due to its potential applications in water treatment, searching for highly efficient photocatalytic materials is highly desirable. Herein, we have prepared a series of biochar(BC)/ZnFe2O4 magnetic nanocomposites by the calcination-hydrothermal two step method. BC/ZnFe2O4 owns improved photoabsorption from 400 to 1300 nm. PL spectra of BC/ZnFe2O4 shows a weaker intensity compared with BC and ZnFe2O4, and BC/ZnFe2O4 generates a stronger photocurrent density (~ 0.08 μA cm-2) than that of BC (0) or ZnFe2O4 (0.03 μA cm-2) under the visible light irradiation, implying efficient separation efficiency of photogeneration carriers. The investigation of pH (3, 5, 7, 9, 11) sensitivity of BC/ZnFe2O4 demonstrates that removal efficiency of Cr(VI) achieves the highest rate at pH = 3.