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

Abstract

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 (·OH) and superoxide (·O₂ ⁻) 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.

Keywords

straw / Cu₂O / Fe₃O₄ / photocatalysis / visible light