Synthesis and application of Fe3O4/FeWO4 composite as an efficient and magnetically recoverable visible light-driven photocatalyst for the reduction of Cr(VI)

Abstract Fe3O4/FeWO4 composites with different compositions were synthesized via hydrothermal way, and characterized by many compositional and structural analysis techniques. 20% Fe3O4/FeWO4 showed the highest efficiency in photocatalytic reduction of aqueous Cr(VI) under visible light (λ > 420 nm) irradiation. Its photocatalytic rate is about 4.4 times as that of Fe3O4 and 1.5 times as that of FeWO4. Moreover, its photocatalytic stability was also good. According to the photoelectrochemical test results, the photocatalytic improvement mechanism of 20% Fe3O4/FeWO4 was proposed. Results from photocatalytic treatment of diluted black chromium plating solution (DBCPS) indicated that 20% Fe3O4/FeWO4 had noteworthy activity in visible light-driven photocatalytic reduction of DBCPS over a wide range of pH (3–11), but its photocatalytic efficiency was higher at lower pH. Besides, 20% Fe3O4/FeWO4 had fairly strong magnetism and could be recovered efficiently using a magnet. Hence, Fe3O4/FeWO4 composite photocatalyst holds potential for application in the treatment of Cr(VI) wastewater.