Photocatalytic oxidation and simultaneous removal of arsenite with CuO/ZnO photocatalyst

• CuO/ZnO demonstrated a significantly improved performance than pure ZnO for the oxidation of As(III).
• Adsorption of As(III) reached the equilibrium rapidly, but As(V) slowly.
• Oxidation efficiency decreased with the increase of initial concentration while the adsorption amount of As increased.
• Adsorption of As(V) onto catalyst surface was larger than As(III).
• Removal of As(III) by photocatalytic treatment was 6.5 times higher than those obtained by adsorption in the dark.

We investigated the photocatalytic oxidation and simultaneous removal of arsenite in synthetic aqueous As solution with high concentration. The process was performed by using CuO/ZnO nanoparticles under UV irradiation at around neutral pH. The effects of CuO addition, initial arsenite concentration and photocatalyst loading on the treatment efficiency were investigated. Adsorption of arsenic onto catalytic surface was evaluated with fourier-transform infrared spectroscopy (FTIR) and X-ray photoelectron spectroscopy (XPS). Batch results showed it that CuO has a significant effect on the photocatalytic performance of ZnO. The rate constant of photocatalytic oxidation with CuO(20%)/ZnO was 4 times better than those obtained with pristine ZnO. The removal amount (mg g−1) of arsenic increased with an increase in initial arsenic concentration. As(III) solution of 30 mg L−1 could be completely removed with photocatalyst of 0.67 g L−1 during 10 h of irradiation time. The maximum As(III) removal amount by photocatalytic oxidation and simultaneous removal was 6.5 times larger relative to that observed in the adsorption in dark. The excellent photocatalytic oxidation and high uptake performances make CuO/ZnO a potentially attractive candidate for the removal of As(III) from highly arsenic contaminated water.