Visible-light-driven reduction of chromium (VI) by green synthesised cuprous oxide nanoparticles

• The Prunus cerasifera extract used as a greener reducing agents for the synthesis of Cu 2 O NPs. • XRD, FT-IR, SEM and EDX confirms the formation and morphology of Cu 2 O NPs. • Efficient visible light reduction of Cr(VI) to Cr(III) achieved by Cu 2 O NPs. • Statistical optimization based on Response surface methodology predicts 99 % reduction. The photocatalytic reaction is the best alternative for the reduction of hexavalent chromium (Cr (VI)) to a less toxic trivalent chromium (Cr (III)). However, getting photocatalysts working in the visible region is yet the key issue for the field. Hence, we have reported an environmentally friendly, and cost-effective synthesis of visible light active cuprous oxide (Cu 2 O) using prunus cerasifera plant extract. The phytochemicals from Prunus cerasifera extract are used as surface modifying and reducing agents for the synthesis of Cu 2 O nanoparticles (NPs). The powder XRD, FT-IR spectroscopy, SEM and EDX instruments were used to confirm the crystal structure, morphology and composition of Cu 2 O NPs. Photocatalytic activity of Cu 2 O NPs investigated via the reduction of Cr (VI) under visible light irradiation. The results showed that Cu 2 O NPs can efficiently reduce Cr (VI). Response surface methodology coupled with Box Behnken Design (RSM-BBD) statistical model was used to optimize the photocatalysis factors and predicted 99% reduction efficiency at pH = 5.95, time 160 min and 15.68 mg/L Cr (VI). The kinetics and plausible mechanism were proposed based on the experimental results.