Enhancing electron transfer by amorphous FeOOH quantum dots during photocatalytic ozonation of ibuprofen

• FeOOH QDs exhibited the better PCO activity for IBP degradation over α- and β-FeOOH. • Tetrahedral Fe 3+ played important role over octahedral Fe 3+ in PCO activity of FeOOH. • Narrower Eg and lower e cb - - h vb + combination of FeOOH QDs enhanced its PCO efficiency. • •OH was the major reactive species accounting for the improved IBP degradation. Photocatalytic ozonation (PCO) process, as an effective water purification technology, was restrained by the low mass transfer and easy combination of photo-carriers ( e cb - - h vb + ) of conventional semiconductor catalysts. To these end, this study synthesized FeOOH quantum-dots (FeOOH QDs) and boosted the PCO activity by its amorphous structure with Ibuprofen (IBP) as model pollutant. 81.5 % IBP was removed by FeOOH QDs PCO, but it was 59.1 % and 61.2 % for α-FeOOH and β-FeOOH PCO, respectively. FeOOH QDs PCO performed well at alkaline environment but was easily inhibited by co-existing ions like SO 4 2- , HCO 3 – , NO 3 – , and Cl - . Compared with those of α-FeOOH and β-FeOOH, FeOOH QDs had the narrowest band gap and the lowest e cb - - h vb + recombination, therefore, its e cb - was more favorable to activate O 3 into •OH. Tetrahedral Fe 3+ and octahedral Fe 3+ co-existed on FeOOH QDs and the tetrahedral Fe 3+ was more conducive to the adsorption of O 3 and contributed to its better PCO activity. •OH was the major reactive oxygen species accounting for IBP degradation. During FeOOH QDs PCO process, 3 degradation routes were proposed basing on 13 kinds by-products. T.E.S.T. result indicated that most of the intermediates were less toxic than IBP. This study is useful for developing catalysts for PCO process.