Magnetically Separable Straw@Fe3O4/Cu2O Composites for Photocatalytic Degradation of Methyl Orange under Visible Light Irradiation

Fe3O4 and Cu2O were successively immobilized on alkali-treated straw, and the magnetically separable straw@Fe3O4/Cu2O composite was obtained. The straw@Fe3O4/Cu2O was characterized by Fourier transform infrared spectroscopy, X-ray diffraction, scanning electron microscopy, X-ray photoelectron spectroscopy and vibrating sample magnetometry, respectively. Photocatalytic performance of the straw@Fe3O4/Cu2O was evaluated by measuring the degradation of methyl orange (MO) under irradiation of visible light. The introduction of Fe3O4 not only endowed the straw@Fe3O4/Cu2O with magnetic separation feature but also significantly enhanced photocatalytic activity because Fe3O4 could prevent recombination of hole-electron pairs. The active species capture experiment showed that holes (h(+)), hydroxyl (<middle dot>OH) and superoxide (<middle dot>O-2(-)) radicals all took part in the MO degradation. In addition, the photocatalytic mechanism of straw@Fe3O4/Cu2O was proposed based on the experimental results. After five cycles for the photodegradation of MO, the straw@Fe3O4/Cu2O still displayed good photocatalytic activity, suggesting that the as-prepared composite had great potential for practical use in wastewater treatment.