Cuprous oxide/titanium dioxide composite photocatalytic decolorization of reactive brilliant red X-3B dyes wastewater under visible light

Abstract

In recent years, how to improve photocatalytic performance under visible light has become one of the research hot topics. The nano-TiO2 particles were synthesized by the sol–gel method, and with different n(Ti)/n(Cu) molar ratios, Cu2O/TiO2 composite photocatalysts were prepared. Nano-TiO2 and Cu2O/TiO2 composite photocatalysts were characterized by X-ray diffraction and scanning electron microscopy. Under the high-pressure mercury lamp irradiation (λ < 600 nm), the photocatalytic decolorization of simulated reactive brilliant red X-3B (X-3B) dye wastewater has been implemented by using Cu2O/TiO2 composite photocatalyst. The influence of titanium dioxide sintering temperature, the molar ratio of n(Ti)/n(Cu), initial different pH values, and reaction temperature on the decolorization of X-3B has been investigated. The results show that the prepared TiO2 has the best photocatalytic property at the sintering temperature of 550 °C and the X-3B decolorization rate of Cu2O/TiO2 composite photocatalyst is much higher than that of bare TiO2 catalyst. Under the irradiation of high-pressure mercury lamp, Cu2O/TiO2 composite photocatalyst with the n(Ti)/n(Cu) molar ratio of 1:1 was prepared, and 200 mL of 25 mg/L X-3B dye was degraded with 0.1g composite photocatalyst, initial pH is 1.0, reaction temperature is 45 °C, and the decolorization rate can reach 91.57% after 60 min reaction. The photocatalytic decolorization procedure conforms to the quasi-first-order reaction kinetic equation. The possible reaction mechanism and pathway to X-3B decolorization by Cu2O/TiO2 photocatalyst were also proposed.