The ZnO/Bi ₂ WO ₆ sheet structure was synthesized by a simple two-step hydrothermal method, and the structure in which the sheet was in close contact with the sheet improved the photocatalytic performance of Bi ₂ WO ₆ . Under simulated sunlight, ZnO/Bi ₂ WO ₆ showed excellent photocatalytic activity for the degradation of phenolic contaminants. The degradation rate of (1:1) ZnO/Bi ₂ WO ₆ to phenol, p-nitrophenol and p-chlorophenol was about 4 times, 7.69 times and 5 times than pure Bi ₂ WO ₆ , respectively. The increase in photocatalytic activity is attributed to the Z scheme heterostructure formed by the two semiconductors, which can effectively separate photogenerated carriers. Compared with a single catalyst, ZnO/Bi ₂ WO ₆ exhibits excellent charge transport properties in photoelectric conversion. Trap experiments of active species have shown that h + and play a major role in photocatalysis. This study proposes a feasible solution for the treatment of a class of pollutant wastewater.

CuO/CNT/Bi ₂ WO ₆ composites were synthesized with a solvothermal and impregnation-calcination method. This material combines the advantages of CuO, carbon nanotubes (CNTs) and Bi ₂ WO ₆ . The photocatalytic activity of the catalyst was evaluated by degrading phenolic organic pollutants such as p-nitrophenol and phenol under visible light. Compared with pure Bi ₂ WO ₆ , the photocatalytic activity of CuO/CNT/Bi ₂ WO ₆ composites is significantly increased by a factor of 3.52. The main reason for the increased activity is that the doped CNTs and CuO promote the separation of photogenerated hole and electron pairs. In addition, the coupling of π-π electrons on the CNT surface with the pollutants promotes the adsorption of the pollutants on the photocatalyst surface. The degradation rate of pure photocatalytic degradation of phenol can reach 60%. Under the synergistic effect of H ₂ O ₂ , the degradation rate of phenol can reach 94%, which is 1.56 times higher than that of pure photocatalysis. The UV–vis absorption spectrum shows that CuO/CNT/Bi ₂ WO ₆ has stronger light absorption ability in both visible and ultraviolet light regions. The trapping experiments of active species show that h + and • OH are the main active substances for photocatalytic degradation of phenol. This paper proposes a Z scheme mechanism to improve the photocatalytic performance.

The complexity of fluid dynamics in a slurry bubble column reactor introduces significant uncertainty in reactor design and scale-up. This paper investigates the hydrodynamic performance of the gas–liquid–solid system within the reactor by employing computational fluid dynamics-population balance modeling numerical simulations alongside particle image velocimetry (PIV) experiments. The effect of superficial gas velocity and particle conditions on the overall gas holdup were analyzed, focusing on the effects of particle size and solid concentration on bubble size, bubble behavior, flow field structure, and local gas holdup distribution at high superficial gas velocities. Bubble size was evaluated using calibrated image measurements, and the impact of varying solid conditions was thoroughly explored. The results revealed that an increase in solid size correlated with higher gas holdup and smaller bubble sizes, whereas a greater solid concentration resulted in decreased gas holdup and larger bubble sizes. PIV experiments indicated that bubbles exhibited a tendency to migrate toward the central region of the reactor, leading to the formation of larger bubbles that accelerated the rise of surrounding bubbles, while smaller bubbles near the wall moved downward. As the slurry bed height increased, the range of local gas holdup distribution expanded, resulting in a symmetrical distribution of radial local gas holdup in the fully developed stage at a height of 0.16 m.