Photosensitivity of ferrate(VI) in tetracycline degradation: role of solar irradiation and reactive species

The purpose of this study was to investigate the photosensitivity of hexavalent ferrate(VI) Fe(VI) and identify its main reactive species during pollutant degradation under solar irradiation. Using tetracycline hydrochloride (TC) as the target pollutant, the degradation efficiency of Fe(VI) was evaluated under dark, simulated solar, natural sunlight, and ultraviolet (UV) conditions. The degradation efficiency reached 81.4% under simulated solar, 80.3% under natural solar, and 76.7% under UV, versus 73.24% in the dark. The results demonstrated that compared with the UV-Fe(VI) process, the solar-Fe(VI) process achieved a higher TC degradation rate. Singlet oxygen was identified as the main reactive species responsible for enhancing the efficiency of Fe(VI)-mediated TC degradation under solar irradiation. Furthermore, visible light exerted no significant promotional effect on the self-decomposition of Fe(VI), whereas UV light significantly accelerated this process.