Synthesis of visible light-responsive cuprous oxide/sunflower stem pith hybrid materials for detoxification of methylene blue

Abstract

The detoxification of dye-contaminated water by photocatalysis has become a research priority. Here, a novel hybrid material, cuprous oxide/sunflower stem pith (Cu2O/SSP), was successfully synthesized in situ, using copper hydroxide gel, prepared by ion exchange, as the precursor to Cu2O. The presence of Cu2O nanoparticles on the SSP was confirmed by scanning electron microscopy, Fourier transform infrared spectroscopy and X-ray diffraction analyses. Using methylene blue (MB) as the target pollutant, Cu2O/SSP delivered excellent adsorption–photocatalytic degradation and was readily photoregenerated. Cu2O/SSP removed 72.7% of MB after 60 min under visible light irradiation, an increase of 15.6 % compared with unmodified SSP. SSP plays three roles in the removal of MB: it acts as an adsorbent for the MB, a carrier for the Cu2O nanoparticles and it also inhibits photocorrosion of Cu2O. The mechanism of adsorption–photocatalysis by Cu2O/SSP was investigated and a description of the mechanism is provided. This study paves the way for the detoxification of dye-containing wastewater using hybrid biomass materials. HIGHLIGHTS Cu2O/SSP was synthesized in situ using copper hydroxide gel, prepared by ion exchange, as the precursor to Cu2O.; Cu2O nanoparticles were well scattered and anchored to the surface of SSP.; The Cu2O combined with SSP was effective at inhibiting photocorrosion of Cu2O.; Cu2O/SSP showed excellent adsorption–photocatalytic and photoregeneration performance.; The adsorption–photocatalysis mechanism for the MB detoxification was discussed.;

Keywords

• adsorption–photocatalysis
• cuprous oxide
• ion exchange
• methylene blue
• sunflower stem pith