Tri(2-chloroisopropyl) phosphate (TCPP), a common organophosphate flame retardant , was frequently detected in the environment and posed threats to human health. In this work, the main component of ilmenite FeTiO 3 was synthesized by the sol-gel method and employed as the catalyst for the degradation of TCPP by activating persulfate (PS) under UV irradiation. The degradation processes were fitted by the pseudo-first-order kinetic. The k obs value in UV/FeTiO 3 /PS system was up to 0.0056 min −1 and much higher than that in UV/PS (0.0014 min −1 ), UV/FeTiO 3 (0.0012 min −1 ) and FeTiO 3 /PS (0.0016 min −1 ) systems, demonstrating a distinct synergistic effect in TCPP removal . The degradation efficiency of TCPP increased with the increase of UV intensity, PS concentration and catalyst dosage, and with the decrease of pH. By quenching experiment and EPR analysis, ·OH was confirmed to be the dominant radical in the reaction of the UV/FeTiO 3 /PS system. The possible degradation pathways of TCPP were dechlorination , dealkylation, and further oxidation of alkyl groups based on the theoretical calculation of frontier molecular orbits. The toxicity of degradation intermediates evaluated by luminescence inhibition rate of photoluminescence was higher than TCPP. Thus, TCPP can be degraded in the UV/FeTiO 3 /PS system effectively at the premise of introducing controlling measures to reduce the toxicity of degradation intermediates.
Da Wang,Stefanos Giannakis,Jingyu Tang,Kai Luo,Juntao Tang,Zhiqiao He,Shuang Song,Lizhang Wang
In this work, we synthesized magnetic reduced graphene oxide (rGO) encapsulated hexagonal FeTiO 3 (FTO@rGO) nanosheets with rGO loading amount of 0, 1, 5 and 10 wt%, with a primary objective of efficiently degrading venlafaxine (VLF) through photo-Fenton processes across a wide pH range of 3–11. The inherent visible-light photocatalytic ability of ilmenite FeTiO 3 (FTO) and catalytic activation of H 2 O 2 by Fe sites during the photo-Fenton process were established. Through the strategic integration of rGO, all FTO@rGO catalysts show higher VLF degradation rate than FTO in photo-Fenton evolution experiments and the FTO@rGO catalysts with rGO loading amount of 5 wt% presents the highest VLF degradation rate (100 % VLF degradation at 90 min), which attributed to the accelerated migration of photo-generated electrons and the efficient Fe 2+ /Fe 3+ cycle. Furthermore, the encapsulation of rGO significantly mitigated Fe leaching throughout the reaction pH range, directing H 2 O 2 activation to occur at the FTO@rGO interface instead of in solution. Through a comprehensive analysis, we identified 47 intermediate products of VLF and deduced the degradation pathway based on 12 representative intermediates. The degradation process was primarily driven by hydroxyl radicals as the dominant reactive oxygen species, complemented by the contribution of superoxide radicals, photogenerated electrons, and holes during the FTO@rGO-catalyzed photo-Fenton process. This study not only expands the application of ilmenite in the realm of advanced oxidation processes (AOPs) but also provides valuable insights for the future exploration and development of metal oxide/carbonaceous heterostructure catalysts.
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