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Oxygen vacancies (OVs)-rich α-Ni 0.2 Fe 1.8 O 3 with dual metal sites was synthesized by Ni2+ isomorphously substituted α-Fe 2 O 3 to activate peroxymonosulfate (PMS) for aceclofenac (ACF) degradation. A novel insight was proposed for the overlooked role of H 2 O in the surface-complexed process between PMS and unsaturated metal sites induced by OVs. The surface-bond SO 4 ∙- and ∙OH were demonstrated as the dominant reactive oxygen species (ROS). In situ ATR and Raman spectra revealed the reaction of HSO 5 - with the surface metal sites by replacing the surface-bonded -OH. The DFT study revealed the spontaneous formation of hydrolyzed -OH on OVs (∆G=−1.45 eV), which was further replaced by HSO 5 - to complex with metal sites (∆G=−3.58 eV). The O Ⅰ of the H-O Ⅰ -O Ⅱ -SO 3 - was more readily bonded with the Ni or Fe sites around OVs, causing the O-O cleavage for SO 4 ∙- generation. This study proposed a brand-new perspective for the interfacial behavior of PMS activation. [Display omitted] • The α-Ni 0.2 Fe 1.8 O 3 with rich oxygen vacancies can excellently activate PMS. • The surface-bond SO 4 ∙- and ∙OH played a major role in the degradation of ACF. • HSO 5 - was mainly bonded to metal sites by replacing surface -OH groups. • The interfacial mechanism for PMS activation by α-Ni 0.2 Fe 1.8 O 3 was proposed. • The degradation pathway of ACF by α-Ni 0.2 Fe 1.8 O 3 /PMS system was deduced. [ABSTRACT FROM AUTHOR]

[Display omitted] • A heterogeneous catalytic system of NaBiO 3 for PMS without light irradiation was investigated. • Both radical (SO 4 −• and •OH) and non-radical (1O 2) were contributed to BPAF degradation. • The contribution rate of 1O 2 , · SO- 4, and · OH was calculated as 80.4%, 8.7%, and 9.9%, respectively. It has been shown previously that the NaBiO 3 (NBO) could efficiently photocatalytically degrade organic contaminants because of its excellent photocatalytic property. In this study, we proposed a heterogeneous catalytic system of NBO for peroxymonosulfate (PMS) without light irradiation. The results showed that NBO/PMS exhibited excellent performance toward bisphenol AF (BPAF) degradation and mineralization. The effectiveness of the NBO/PMS system was also investigated in different multicomponent systems. The effects of initial pH, NBO dosages, and PMS concentration for BPAF degradation were also investigated. Radical quenching experiments combined with electron spin resonance analysis indicated that singlet oxygen (1O 2) was the main reactive oxygen species, and · SO 4 - and · OH– radicals participated in the process. X-ray photoelectron spectroscopy revealed the main catalytic mechanism: lattice oxygen (O vac) was extruded during the transformation of Bi(V) to Bi(III) to form and activate oxygen (O*), and the generated O* between the [BiO 6 ] regular octahedral layers reacted with PMS on the NBO surface to form 1O 2. Based on the results of the Bi element, it is suggested that the activation process proceeded through electron transfer from NBO to PMS. The stability of NBO and applicability of the NBO/PMS system in a natural water environment were explored. This work provides a novel approach to PMS activation and the potential use of NBO for the decontamination of organic pollutants. [ABSTRACT FROM AUTHOR]

[Display omitted] • An effective way for treating high-salinity organic wastewater was developed. • CuO/MXene nanocomposite was prepared to activate PMS for carbamazepine degradation. • CuO/MXene/PMS system presented > 95.88% removal of carbamazepine within 20 min. • The inhibition of inorganic anions was conquered by CuO/MXene/PMS system. • 1O 2 was identified as dominant ROS and its contribution was verified. The degradation of organic contaminants via traditional radical-dominated advanced oxidation processes (AOPs) under high salinity conditions was limited due to side reactions between coexisting inorganic anions and radicals. Herein, a nonradical oxidation process via peroxymonosulfate (PMS) activation by CuO/MXene for treating high-salinity organic wastewater was developed. Rapid removal efficiency of target pollutant carbamazepine (CBZ) was significantly enhanced to 95.88% within 20 min by CuO/MXene under high salinity conditions (NaCl, 200 mM), compared to the efficiency of 4.30% exhibited by PMS alone. Besides, CBZ maintained a higher removal efficiency of > 81.04% in complex highly saline wastewater composed of eight common inorganic anions. Radical quenching experiments and electron paramagnetic resonance (EPR) analysis confirmed that radical and nonradical oxidation processes were involved in the catalytic process. However, singlet oxygen (1O 2) was identified as the primary reactive species, and its contribution rate to CBZ degradation was > 73.58% in a wide pH range (3.0-9.0). The oxygenated functional groups and the interaction between CuO/MXene and PMS facilitated the production of 1O 2. The degradation pathway was proposed based on the detection of intermediates. This work provided a new inspiration for the decontamination of organic contaminants under high salinity conditions via a nonradical oxidation process. [ABSTRACT FROM AUTHOR]

• Fe and O codopants substantially accelerated the electron transfer of g-C 3 N 4 for PMS activation. • Efficient BPA removal was achieved at high salinity and within wider pH ranges. • High-valent iron-oxo species and singlet oxygen were identified as two main reactive species. • Nonradical pathways were elucidated based on experimental and theoretical analyses. Peroxymonosulfate (PMS)-based advanced oxidation processes (AOPs) for wastewater treatment have recently attracted widespread interests. However, the degradation of organic pollutants via traditional radical-dominated pathway is severely limited by the side reactions between radicals and the co-existing inorganic anions, especially under high salinity conditions. Herein, an efficient Fe/O co-doped g-C 3 N 4 nanosheet catalyst was synthesized to dominantly activate PMS through a dual non-radical pathway with the singlet oxygen and high-valent iron-oxo species (Fe(V)=O). The rapid degradation of model pollutant bisphenol A (BPA) was achieved by dosing PMS (1 mM), catalyst (0.1 g/L) in a simulated high-salt wastewater (≥200 mM) of the developed Fe/O-doped g-C 3 N 4 +PMS system with a reaction rate constant of 1204-fold higher than that in g-C 3 N 4 +PMS system. The O and Fe co-dopants could reconfigurate the electronic structure of pristine g-C 3 N 4 to produce more non-radical active species. The formed Fe(V)=O played a main role in the BPA degradation by promoting electron transfer from BPA molecule to the "metastable PMS/catalyst complex", which was verified by electrochemical tests and density functional theory calculations. The auxiliary transient productions of · OH+SO 4 · – species were also favorable for the pollutant degradation. Excellent reusability in a wide pH range confirmed the practical application prospects of the Fe/O-doped g-C 3 N 4 +PMS system. The successive addition of PMS with a low dosage into the system rich in pollutants was confirmed to favor the PMS utilization. Our work unveils the potential applications of a non-radical dominated process for the decontamination of organic pollutants in saline water. [ABSTRACT FROM AUTHOR]