Photocatalytic purification of simulated dye wastewater in different pH environments by using BaTiO3/Bi2WO6 heterojunction photocatalysts

To reveal the photodegradation process of mixture dye solutions in different pH environments by photocatalysts is a key point to promote the practical application of potocatalysis technology in purifying industrial dye wastewater. Herein we report the photocatalytic degradation of various organic dyes (MO, RhB, MB) and MO/RhB/MB mixture solutions in different pH environments by using novel BaTiO3/Bi2WO6 (BTO/BWO) heterojunction composites as the photocatalyst and simulated sunlight as the light source. The BTO/BWO heterojunction photocatalysts were prepared by immobilizing BTO particles onto rose flower-like BWO hierarchical architectures. Among the as-derived samples, the 15 wt%BTO/BWO composite is determined to have the highest photodegradation performance, which is ascribed to the efficient separation of photoexcited electron/hole pairs due to the Z-scheme electron transfer mechanism. The photodegradation of the dyes is found to be highly dependent on the acidic–alkaline environments. Moreover, an interesting competitive photodegradation phenomenon between the dyes is observed in the MO/RhB/MB mixture solutions. Superoxide (•O2−) and hydroxyl (•OH) radicals are suggested to be the direct reactive species causing the dye photodegradation in the present photocatalytic system.