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

Fe 3 O 4 and Cu 2 O were successively immobilized on alkali-treated straw, and the magnetically separable straw@Fe 3 O 4 /Cu 2 O composite was obtained. The straw@Fe 3 O 4 /Cu 2 O 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@Fe 3 O 4 /Cu 2 O was evaluated by measuring the degradation of methyl orange (MO) under irradiation of visible light. The introduction of Fe 3 O 4 not only endowed the straw@Fe 3 O 4 /Cu 2 O with magnetic separation feature but also significantly enhanced photocatalytic activity because Fe 3 O 4 could prevent recombination of hole-electron pairs. The active species capture experiment showed that holes (h + ), hydroxyl (·OH) and superoxide (·O 2 − ) radicals all took part in the MO degradation. In addition, the photocatalytic mechanism of straw@Fe 3 O 4 /Cu 2 O was proposed based on the experimental results. After five cycles for the photodegradation of MO, the straw@Fe 3 O 4 /Cu 2 O still displayed good photocatalytic activity, suggesting that the as-prepared composite had great potential for practical use in wastewater treatment.