Accelerated TiO₂ photocatalytic degradation of Acid Orange 7 under visible light mediated by peroxymonosulfate
2012
Chen, Xiaoyang | Wang, Weiping | Xiao, Hua | Hong, Chunlai | Zhu, Fengxiang | Yao, Yanlai | Xue, Zhiyong
In this study, a system involving visible light TiO₂ photocatalysis (Vis/TiO₂) coupled with SO₄ ⁻-based advanced oxidation technologies (AOTs) through the addition of the oxidant peroxymonosulfate (PMS, HSO₅ ⁻) has been developed to oxidize the target pollutant Acid Orange 7 (AO7) in aqueous solutions. There existed a remarkable synergistic effect in the combined Vis/TiO₂/PMS system, and the performance of this combined system was better than that of a system to which persulfate (PS, S₂O₈ ²⁻) or hydrogen peroxide (H₂O₂) was added. The influence of humic acids (HAs) and inorganic anions (H₂PO₄ ⁻ and HCO₃ ⁻) on the degradation rates in the Vis/TiO₂/PMS system was also investigated. The obtained results revealed that HAs had a positive effect on the AO7 degradation efficiency in the Vis/TiO₂/PMS system. When added to the Vis/TiO₂ system, PMS can abrogate the adverse interference of anions in this system, such that the Vis/TiO₂/PMS system exhibits much better degradation rates. The primary degradation intermediates of AO7 identified by GC/MS were phthalic acid, 2,4,6-trichlorophenol, coumarin and two chlorinated aromatic compounds (7-chloro-2-naphthalenol and 2,4-dichloro-1-naphthalenol). A possible pathway was proposed based on the analysis of the degradation products.
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