Efficient chlorination reaction of Pt/RuO/g-CN under visible light irradiation for simultaneous removal of ammonia and bacteria from mariculture wastewater.

The removal of ammonia nitrogen (NH-N) and bacteria from aquaculture wastewater holds paramount ecological and production significance. In this study, Pt/RuO/g-CN photocatalysts were prepared by depositing Pt and RuO particles onto g-CN. The physicochemical properties of photocatalysts were explored by X-ray photoelectron spectroscopy (XPS), scanning electron microscopy (SEM), X-ray diffraction (XRD), and UV-vis diffuse reflectance spectrometer (UV-vis DRS). The photocatalysts were then applied to the removal of both NH4+-N and bacteria from simulated mariculture wastewater. The results clarified that the removals of both NH-N and bacteria were in the sequence of g-CN < RuO/g-CN < Pt/g-CN < Pt/RuO/g-CN. This magnificent photocatalytic ability of Pt/RuO/g-CN can be interpreted by the transfer of holes from g-CN to RuO to facilitate the in situ generation of HClO from Cl in wastewater, while Pt extracts photogenerated electrons for H formation to enhance the reaction. The removal of NH-N and disinfection effect were more pronounced in simulated seawater than in pure water. The removal efficiency of NH-N increases with an increase in pH of wastewater, while the bactericidal effect was more significant under a lower pH in a pH range of 6-9. In actual seawater aquaculture wastewater, Pt/RuO/g-CN still exhibits effective removal efficiency of NH-N and bactericidal performance under sunlight. This study provides an alternative avenue for removement of NH-N and bacteria from saline waters under sunlight.