Synthesis, physical properties and application of the zero-valent iron/titanium dioxide heterocomposite having high activity for the sustainable photocatalytic removal of hexavalent chromium in water

A magnetic photocatalytic material composed of nanoscale zero-valent iron (nZVI) homogeneously distributed over a mesoporous nanocrystalline TiO 2 matrix has been prepared by a multistage chemical process, including solgel technique, wet impregnation, and chemical reduction. X-ray powder diffraction and Raman spectroscopy were used for the structural and chemical characterization of the magnetic photocatalyst, while bulk magnetization measurements and scanning/transmission electron microscopy were employed to determine the physical and textural properties of the photocatalyst. The synthesized nZVI@TiO 2 photocatalyst shows very high efficiency in the removal of hexavalent chromium, Cr( vi ), from water. The degradation rate follows a pseudo-first-order kinetic model. Most importantly, the remarkable efficiency of the photocatalyst is found to be due to the synergistic contributions of both counterparts, nZVI and TiO 2 , as validated by comparative experiments with neat TiO 2 and nZVI@TiO 2 under UV-C irradiation and without irradiation. New insights into the mechanism of synergistic degradation of chromium( vi ) and suppressed oxidation of nZVI particles in the composite material are proposed and therein discussed. A magnetic photocatalytic nanocomposite was prepared with enhanced removal capability for Cr( vi ) due to synergistic effects.