Visible-light-induced activation of peroxymonosulfate by TiO2 nano-tubes arrays for enhanced degradation of bisphenol A

TiO 2 photocatalysis and peroxymonosulfate (PMS) oxidation can exhibit a good performance in ultraviolet light but a less activity in visible light (VL). Herein, the TiO 2 nano-tubes arrays (TiO 2 NTAs) and PMS were combined to degrade bisphenol A (BPA) under VL irradiation. Surprisingly, about 94.6% of BPA was removed in TiO 2 NTAs/PMS/VL system within 30 min, which was much higher than that of TiO 2 NTAs/VL (20.1%) and PMS/VL (9.4%) systems. A series of spectroscopic characterizations and photoelectrochemical measurements confirmed the formation of PMS-TiO 2 complex with VL response, which can be excited by VL to transfer electrons to the   conduction   band (CB) of TiO 2 for activating PMS. The quenching tests and electron spin resonance (ESR) spectra indicated that SO 4 •− and · OH were responsible for BPA degradation, and then the possible degradation pathways of BPA were proposed. Humic acid (HA) and chloride ions (Cl − ) significantly enhanced the BPA degradation, while bicarbonate (HCO 3 – ) and phosphate (H 2 PO 4 − ) exhibited an inhibition effect. Moreover, TiO 2 NTAs/PMS/VL system displayed an enhanced BPA degradation in tap water and drinking water compared with deionized water, and as an immobilization catalyst which fabricated on Ti plate, TiO 2 NTAs exhibited excellent stability and separability without complex catalyst separation/recovery processes. We believe this work will provide a new insight of the VL-induced photocatalytic PMS activation in practical water treatment.