title: Surface-active bismuth ferrite as superior peroxymonosulfate activator for aqueous sulfamethoxazole removal: Performance, mechanism and quantification of sulfate radical.
abstract: A surface-active Bi2Fe4O9nanoplates (BF-nP) was prepared using a facile hydrothermal protocol for sulfamethoxazole (SMX) removal via peroxymonosulfate (PMS). The catalytic activity of BF-nP was superior to other catalysts with the following order of performance: BF-nP>Bi2Fe4O9(nanocubes)>>Co3O4>Fe2O3(low temperature co-precipitation method)>Fe2O3(hydrothermal method)∼Bi2O3∼Bi3+∼Fe3+. The empirical relationship of the apparent rate constant (kapp), BF-nP loading and PMS dosage can be described as follows: kapp=0.69[BF-nP]0.6[PMS]0.4(R2=0.98). The GC-MS study suggests that the SMX degradation proceed mainly through electron transfer reaction. The XPS study reveals that the interconversion of Fe3+/Fe2+and Bi3+/Bi5+couples are responsible for the enhanced PMS activation. The radical scavenging study indicates that SO4-is the dominant reactive radical (>92% of the total SMX degradation). A method to quantify SO4-in the heterogeneous Bi2Fe4O9/PMS systems based on the quantitation of benzoquinone, which is the degradation byproduct of p-hydroxybenzoic acid and SO4-, is proposed. It was found that at least 7.8±0.1μM of SO4-was generated from PMS during the BF-nP/PMS process (0.1gL-1, 0.40mM PMS, natural pH). The Bi2Fe4O9nanoplates has a remarkable potential for use as a reusable, nontoxic, highly-efficient and stable PMS activator.
authors.affiliation: Nanyang Environment and Water Research Institute (NEWRI), Nanyang Technological University, 1 Cleantech Loop, CleanTech One, Singapore 637141, Singapore; Division of Environmental and Water Resources Engineering, School of Civil and Environmental Engineering, Nanyang Technological University, 50 Nanyang Avenue, Singapore 639798, Singapore. Electronic address: wdoh@ntu.edu.sg.
authors.forename: Wen-Da
authors.initials: WD
authors.lastname: Oh
authors.affiliation: Nanyang Environment and Water Research Institute (NEWRI), Nanyang Technological University, 1 Cleantech Loop, CleanTech One, Singapore 637141, Singapore; School of Materials Science and Engineering, Nanyang Technological University, 50 Nanyang Avenue, Singapore 639798, Singapore.
authors.forename: Zhili
authors.initials: Z
authors.lastname: Dong
authors.affiliation: Nanyang Environment and Water Research Institute (NEWRI), Nanyang Technological University, 1 Cleantech Loop, CleanTech One, Singapore 637141, Singapore.
authors.forename: Goei
authors.initials: G
authors.lastname: Ronn
authors.affiliation: Nanyang Environment and Water Research Institute (NEWRI), Nanyang Technological University, 1 Cleantech Loop, CleanTech One, Singapore 637141, Singapore; Division of Environmental and Water Resources Engineering, School of Civil and Environmental Engineering, Nanyang Technological University, 50 Nanyang Avenue, Singapore 639798, Singapore. Electronic address: cttlim@ntu.edu.sg.
authors.forename: Teik-Thye
authors.initials: TT
authors.lastname: Lim
keywords: Bismuth ferrite; Peroxymonosulfate; Sulfamethoxazole; Sulfate radical; p–hydroxybenzoic acid